https://doi.org/10.5370/KIEE.2024.73.10.1609

박성수(Seong-Su Park) ; 임현우(Hyun-Woo Lim) ; 응웬녹득(Ngoc Duc Nguyen) ; 심재웅(Jae Woong Shim)

This paper proposes a method for calculating the required capacity of the Grid-Forming inverter (GFM) according to the inertia requirement in a 100% Inverter-Based Resource (IBR) system. For this purpose, we also suggest a critical inertia calculation method based on Korean grid code. As the basis for the proposed method, using the System Frequency Response (SFR) model, we verified that reinforcing the inertia constant through the integration of GFM contributes to increasing the frequency nadir, and provided a mathematical interpretation of this effect. After that, for the simulation we assume a simulation environment, the 2023 Jeju island system operating at 100% IBR by providing the inertia from GFM, on the PSCAD/EMTDC and derived the required capacity of GFM by applying the proposed method in the constructed simulation system.

https://doi.org/10.5370/KIEE.2024.73.10.1617

소다영(Dayeong So) ; 문지훈(Jihoon Moon)

How can the multistep-ahead prediction of photovoltaic power generation be improved by integrating multivariate time series features in a virtual power plant (VPP) environment? To address this question, this study develops and evaluates a photovoltaic power generation forecasting model that integrates a bidirectional gated recurrent unit (Bi-GRU), a temporal convolutional network (TCN), and a multi-head attention mechanism. Our strategy leverages multi-fusion deep learning (DL), which is known for its ability to synthesize multiple prediction technologies, making it particularly suitable for complex scenarios such as energy forecasting. Leveraging advances in Internet of Things (IoT) and smart grid technologies, this model improves the management and operational efficiency of distributed energy resources (DERs) within VPPs. Validation with real-world data demonstrates that this sophisticated DL framework effectively improves forecasting accuracy by skillfully capturing the temporal dynamics and interdependencies in the data. Such enhanced predictive capabilities are critical to ensuring the reliability and efficiency of energy systems, and can help provide a stable and balanced power supply in a market shifting to renewable energy sources.

https://doi.org/10.5370/KIEE.2024.73.10.1624

최윤일(Youn-Il Choi) ; 김철환(Chul-Hwan Kim)

Due to the recent surge in inverter-based renewable energy sources and DC loads, investments research in DC distribution are progressing. To harness DC systems in industrial settings, it is imperative to establish various systems that ensure continuous power supply, especially during main power outages. In this paper, we aim to assess the reliability of optimally managed operational power components through the analysis of failure histories using the Weibull distribution function. Furthermore, this study seeks to ascertain whether satisfying the appropriate reliability criteria for DC circuit breakers enhances the reliability of AC/DC hybrid systems compared to traditional AC systems.

https://doi.org/10.5370/KIEE.2024.73.10.1631

송원준(Wonjune Song) ; 이우형(Woohyeong Lee) ; 박병권(Byungkwon Park)

This paper proposes the potential application of the Parallel-in-Time (Parareal) algorithm for power system dynamic simulation of larger and more complex future power systems. The uncertainties in future power systems continue to increase due to new elements such as power electronic-based control devices and renewable resources. The aim of this paper is to investigate large-scale time-domain simulations including the effects of stochastic perturbations and ways for its computational enhancement. To this end, this work validates the potentials of the Parareal algorithm to effectively solve stochastic differential-algebraic equations. In particular, this paper demonstrates the convergence of the Parareal algorithm in various fault scenarios and illustrates the computational enhancement of the time-domain simulation using the high-performance computing platforms. Additionally, this paper describes the benefits of stochastic power system dynamic simulations as compared to the deterministic simulations.

https://doi.org/10.5370/KIEE.2024.73.10.1639

김태현(Tai Hyun Kim) ; 이준희(Joon Hee Lee) ; 박종배(Jong-Bae Park) ; 이주원(Joowon Lee) ; 김명수(Myungsu Kim) ; 조홍종(Hong Chong Cho) ; 노재형(Jae Hyung Roh)

This paper analyzes the reduction effects on the SMP (System Marginal Price) and system operation costs in the cost-based pool (CBP) wholesale electricity market due to the participation of dual-fuel LNG-LPG power generators. To assess the cost-saving effects of the introduction of dual-fuel power generators, simulations were conducted using the PLEXOS power market analysis program. The dual-fuel power generators were modeled to flexibly choose and apply the cheaper fuel between LNG and LPG. The analysis was carried out based on historical fuel costs and future fuel cost projections, with supply and demand assumptions derived from actual performance or the 10th Basic Plan for Long-term Electricity Supply and Demand. It was found that in all cases set for the market participation of dual-fuel power generators, there were reductions in SMP, system operation costs, and LNG power purchase costs, thereby increasing the benefits for both suppliers and consumers.

https://doi.org/10.5370/KIEE.2024.73.10.1648

이진환(Jin-Hwan Lee) ; 윤한준(Han-Joon Yoon) ; 김용재(Yong-Jae Kim) ; 정상용(Sang-Yong Jung)

This study analyzes the characteristics of shaft voltage due to rotor overhang in a wound-field rotor synchronous motor(WRSM) for electric vehicle. Recently, WRSM have gained significant attention as alternatives to permanent magnet motors. However, they exhibit disadvantages in torque density compared to permanent magnet motors, since they do not utilize permanent magnets. To solve this drawback, rotor overhang is commonly applied, but this can adversely affect voltage insulation due to end leakage flux. To verify this, models without and with rotor overhang are separately modeled to analyze shaft voltage characteristics. The results confirm the impact of rotor overhang on shaft voltage in the design of WRSM.

https://doi.org/10.5370/KIEE.2024.73.10.1654

권현우(Hyun-Woo Kwon) ; 문주형(Ju-Hyeong Moon) ; 강동우(Dong-Woo Kang)

With the increasing demand for electric vehicles, the use of Permanent Magnet Synchronous Motors (PMSM) which have characteristics such as high efficiency and high energy density has been expanding. For mass production of PMSM, the Post Assembly Magnetization process, where unmagnetized permanent magnets are inserted into the rotor and then magnetized using a magnetization yoke, is used widely. However, for products with a smaller outer diameter rotor than the magnetizer`s inner diameter that does not fit the dedicated magnetization yoke for recycling the magnetizing system, applying the same magnetic field can show results less magnetizing ratio causing increasing leakage flux with the long air gap. Therefore, this paper proposes optimizing the temperature of permanent magnets by heating them to reduce magnet coercivity, achieving the same magnetization performance with the existing magnetizer without increasing the capacity of the magnetization power supply or redesigning the magnetization yoke. This research is expected to enable the use of a universal magnetizer for rotors of different sizes, thereby reducing production costs. The analysis will be conducted using ANSYS Electronics Desktop 2019 R3.

https://doi.org/10.5370/KIEE.2024.73.10.1659

이영달(Young-Dal Lee)

This paper analyzes the trends in the international standardization of EV wireless charging technology, detailing the roles and standards established by major international standard-setting bodies, including IEC, ISO, SAE, and GB/T. Additionally, this paper examines global cooperation and market trends while exploring the latest technological advancements. Through this analysis, this paper identifies technical, economic, and policy challenges and outlines future research directions. This study emphasizes the importance of international standards for the effective implementation and commercialization of wireless EV charging technology.

https://doi.org/10.5370/KIEE.2024.73.10.1670

문운철(Un-Chul Moon) ; 박혜진(Hye-Jin Park) ; 성정원(Jung-Won Sung) ; 곽상신(Sang-Shin Kwak)

In this research, the internal resistance of the input capacitor in the DC/AC single-phase converter, equivalent series resistance (ESR), is estimated by the least mean square method. This paper firstly applied the LMS algorithm to identify the amplitude of the equivalent series resistance of the dc-link capacitor of the dc-ac converters, by using signals of capacitor voltage and current. In addition, conditions for optimal performance were confirmed by adjusting the sampling time of the data. The error was analyzed by comparing the estimated and measured using the algorithm. As a result, it was confirmed that the estimation accuracy was relatively high at 98 % at a capacitor capacity. Furthermore, the algorithm of this paper compared the accuracy according to sampling time and data section. Accordingly, it was confirmed which of the two factors had a greater effect on accuracy. This result is a contribution to this paper. It was confirmed that the sampling time had a greater effect than the section of the data.

https://doi.org/10.5370/KIEE.2024.73.10.1678

방정율(Jeong-Yul Bang) ; 최동호(Dongho Choi) ; 이준석(June-Seok Lee)

This paper proposes a suppression method for abnormal voltage caused by vertical crossing in phase-shifted PWM (PS-PWM)-based multi-sampled cascaded H-bridge (CHB) inverters. In PS-PWM-based CHB, multi-sampling is used to increase the bandwidth of the control loop and to improve transient and steady-state performance. However, in a multi-sampling, missed updates of PWM pulses occur due to vertical crossing, leading to an abnormal output voltage of the CHB. In this paper, the magnitude of CHB voltage error caused by vertical crossing is derived, and the influences of the carrier period on vertical crossing is analyzed in detail. Furthermore, to suppress the abnormal voltage, the occurrence of vertical crossing is predicted by utilizing the values of modulation waves and carriers at each sampling. Once a vertical crossing is predicted, the modulation wave is modulated to update the PWM pulse. The validity of the proposed method is verified by three-cell CHB experiment results.

https://doi.org/10.5370/KIEE.2024.73.10.1687

함고은(Go Eun Ham) ; 김광은(Kwangeun Kim)

There has been increasing attention on the fabrication of power semiconductors and development of device performances using machine learning(ML) model. In this work, ML model was applied to the development of ohmic contacts in GaN for power semiconductor device applications. Factors influencing contact resistivity include work function and electrical affinity of metals, annealing conditions, and doping parameter of GaN. These parameters are set as variables to calculate the contact resistivity of ohmic contacts, which can evaluate the quality of ohmic contacts with low power assumption. Using circular transmission line measurement of Ti/Al ohmic contacts on n-GaN, I-V properties are analyzed to extract the contact resistivity according to the annealing conditions as well as used to train the ML model. By classifying the contact resistivity of n-GaN using ML model, it becomes possible to apply to the fabrication of GaN power devices with low on-resistance in power switching

https://doi.org/10.5370/KIEE.2024.73.10.1692

미르잘랄 파이줄라예프(Mirjalol Fayzullaev) ; 프리모바 홀리다(Primova Holida) ; 오염덕(Ryumduck Oh)

As we all know, predicting traffic flow, maximising movements at crossings, and removing traffic congestion are of utmost importance in the logistics of cities with a significant requirement for public transportation. Traffic congestion results in excessive fuel usage without additional travel, and CO2 emissions contribute to worldwide climate change. To create a sustainable urban logistics system and a sustainable urban transport system, PTV Vissim traffic flow modelling software is mainly employed. This software program is the perfect instrument for this research because it provides a complete range of tools and capabilities for modelling and simulating transportation networks. In this article, an intersection simulation model was created using the PTV Vissim software package. This simulation model was used to investigate junction congestion, emissions, reduced fuel usage, and the detection and optimisation of parking demand. As a research item, the intersection of Ibn Sina and Dahbed streets in Samarkand, Republic of Uzbekistan, was chosen as one of the most troublesome crossroads.

https://doi.org/10.5370/KIEE.2024.73.10.1699

조성진(Sungjin Cho)

Impact angle guidance laws are widely used for miss distance and angle constraints of unmanned aerial vehicles(UAVs). Most research work assumes that UAV speed is constant. However, UAVs equipped with boosters generate time-varying thrust, which results in time-varying vehicle speed. Moreover, autopilot lag, which is an inner loop of a guidance loop, degrades guidance performance because of a delay factor. This paper presents a nonlinear impact angle guidance law that address the delay factor of autopilot and time-varying vehicle speed. The proposed guidance law controls miss distance, impact angle, and cancels autopilot lag. Furthermore, we prove that line-of-sight error of the proposed guidance law is converged in finite time by analyzing Lyapunov Stablity. The proposed algorithm is validated by numerical simulations.

https://doi.org/10.5370/KIEE.2024.73.10.1705

이재원(Jae-Won Lee) ; 최진규(Jin-Kyu Choi) ; 신영철(Young-Cheol Shin) ; 홍순일(Soon-Il Hong) ; 류제덕(Jae-Deok Ryu) ; 김경민(Kyoung-Min Kim) ; 이재웅(Jae-Woong Yi) ; 안세환(Se-Hwan An) ; 주지한(Ji-Han Joo)

This paper summarizes the design and implementation of a broadband signal processor unit to be applied to a small millimeter wave tracking radar. Small millimeter wave tracking radars are based on emitting millimeter waves toward a target and analyzing the returning received signal. The signal processing unit in this paper is designed to process a broadband input signal with an specific center frequency above 100MHz and specific bandwidth in real time by configuring three input channels. At this time, a digital receiver was designed to process broadband input signals. The digital receiver uses a high performance ADC capable of high speed sampling, and DDC(Digital Down Converter) is configured using FPGA, and preprocessing functions include various functions such as DDS(Direct Digital Synthesizer), FIR(Finite Impulse Response) Filter, and Decimation. In addition, FFT(Fast Fourier Transform) and data type conversion processing were applied to reduce the processor load in the post processing stage. The preprocessed three channel large capacity data is delivered to the processor through high speed communication, and a high performance multi core processor and external memory are applied to process it in real time. In addition, an external communication interface was designed to control the entire radar system, and the power supply unit was designed to provide stable power supply. Afterwards, a performance test was conducted to verify the implemented signal processor. Receiving dynamic range and frequency error measurement tests were conducted, and all test met the required. Through this, it was found to be suitable for application of small millimeter wave tracking rader.

https://doi.org/10.5370/KIEE.2024.73.10.1711

남의석(Eui-Seok Nahm)

In this paper, in order to optimize the biological water treatment process, we review three representative methods among XAI's post-hoc explainability techniques. Among them, LIME and AEA methods are applied to the water treatment biological process to find an optimization method. presented. XAI's post-hoc explainability technique is applied to solve the black box problem of not knowing what is attributable to the water treatment artificial intelligence model, which is commonly used in water treatment process optimization, even if it produces good results. We analyzed which control variables were responsible for the improvement in the quality of treated water. As a result of the analysis, it was confirmed that the LIME method had a greater influence on the quality of treated water than the AEA method. In addition, it was found that this method contributes to solving the black box problem and improving the quality of treated water. In the case of the LIME method applied to the water treatment biological process in this paper, although it is not common, it was possible to analyze the characteristics of output variables even for input variables other than control variables by observing the results graphically. In the future, it is believed that by systematizing such graph analysis into an algorithm, it will be possible to propose a more effective LIME method.

https://doi.org/10.5370/KIEE.2024.73.10.1718

김영선(Young-Sun Kim)

This paper presents the concept and implementation of an low frequency power generator using a magnetic nanofluid sloshing phenomena to generate an electro-motive force(emf). Magnetic nanofluids are often applied to power generator because nanofluid have both magnetic properties and mechanical fluidity, and they behave similarly to a soft ferromagnetic material. In addition, magnetic nanofluids have the characteristic that their shape can be freely changed by external force and that they can generate electromotive force even with low frequency or small vibrations. Power generation technology using piezoelectric or thermoelectric elements has limitations in its use because the size of the power is low, at the level of several micro-watts. Here, we developed a model capable of generating power using the flow analysis of magnetic nanofluids and electromagnetic properties based on Faraday's law, and conducted an experimental study. We studied the induced electromotive force characteristics according to the change in magnetic flux density and the amount of magnetic nanofluid using the proposed method, and experimentally verified its validity.

https://doi.org/10.5370/KIEE.2024.73.10.1724

윤현재(Hyunjae Yoon) ; 김인수(Insu Kim)

The Korean central government ministries and local governments are major actors in enacting policies to support the expansion of electric vehicle (EV) charging station infrastructure. However, the installation, operation, and business procedure guidelines are still evolving, leading to many trial-and-error situations. This paper addresses the deficiencies in the guidelines issued by Korea's Ministry of Environment for installing and operating EV charging infrastructure. It proposes solutions to overcome the limitations of the existing guidelines by presenting a new business model not specified in the current guidelines and providing practical measures applicable in the field. Additionally, it suggests a new model for the composition of the business selection committee to ensure fair and systematic administration in the selection of proposers and executing agencies. The goals of the study aim to offer a new perspective on the guidelines for EV charging infrastructure and contribute to the continuous implementation and operation of related projects.

https://doi.org/10.5370/KIEE.2024.73.10.1732

윤용호(Yong-Ho Yoon)

Due to the development of secondary batteries such as lithium-ion batteries, the consumption of previously used lead-acid batteries is decreasing. However, lead acid batteries are still used in many fields, such as batteries for internal combustion engine vehicles, uninterruptible power supplies (UPS), and communication equipment. Compared to lithium-ion batteries, lead acid batteries are relatively safe, have a low risk of explosion and fire, and have strong resistance to temperature changes, so the need for a battery management system (BMS) is lower than that of lithium-ion batteries. However, if a battery management system (BMS), which can monitor and manage the state of charge, temperature, voltage, and current of a lead acid battery, is applied to the lead acid battery, the lifespan, performance, and safety of the battery can be improved. In this paper, we created a battery management system that can be applied to the uninterruptible power supply (UPS), which is used for normal and regular operation of emergency lighting and electrical equipment in the event of a power outage at a railroad station. Through this, we aim to propose a more efficient and safer energy storage method by improving the life, performance, and safety of the battery and increasing the possibility of long-term use.

https://doi.org/10.5370/KIEE.2024.73.10.1738

윤용호(Yong-Ho Yoon) ; 정성인(Sung-In Jeong)

Inside power devices, electrolytic capacitors for power are essentially used for AC/DC linkage for temporary energy storage and filter functions such as voltage smoothing. In particular, as the use of power converters has rapidly increased in the field of new and renewable energy such as PV power generation and the demand for electric vehicles has increased, the use of electrolytic capacitors has increased, and electrolytic capacitors are responsible for most accidents in power conversion devices. Therefore, in this paper, we analyzed the correlation between voltage and capacitance through a capacity-specific deterioration test for DC capacitors of PV inverters that are commercially available. In addition, we studied a compensation module and related algorithms that can detect the degree of electrolytic capacitor deterioration and compensate for the deterioration. Through this research, we aim to improve the safety of PV power generation systems by compensating for the deterioration of electrolytic capacitors and maintaining the continuous performance of PV inverters.

https://doi.org/10.5370/KIEE.2024.73.10.1744

현소영(So-Yung Hyun) ; 왕종용(Jong-Yong Wang) ; 김명훈(Myeong-Hoon Kim) ; 문원식(Won-sik Moon)

According to government support policies such as the Solar Home Distribution Project and Renewable Energy 3020, the amount of waste solar panels is expected to increase exponentially. Currently, when photovoltaic generation facilities are deconstructed, there is an electrical risk (such as electric shock) for workers because the photovoltaic system continues to generate power even after the grid side (KEPCO) is opened. In addition, there is no exist specialized standard-specification to ensure the safety and quality of the facility during deconstruction work. According to the “Solar Power Waste Panel Management Reinforcement Plan” of the Ministry of Trade, Industry and Energy and the Ministry of Environment, a standard-specification will be developed to enforce safety management during deconstruction. Therefore, in order to ensure the safety of on-site workers and construction quality during deconstruction of photovoltaic generation facilities, a standard specification and construction guide for deconstruction photovoltaic generation facilities were developed that reflects the characteristics of deconstruction works and improved accessibility for workers.

https://doi.org/10.5370/KIEE.2024.73.10.1750

이동주(Dong-Ju Lee) ; 김종겸(Jong-Gyeum Kim)

Induction motors are one of the most widely used rotating machines in industrial settings. Since this induction motor is an inductive load, the power factor is relatively low. Induction motors have different efficiency and power factor depending on the number of poles even if the output is the same. Despite these differences in characteristics, when the output of the motor is the same, power factor correction capacitors of the same capacity are often used. In this study, induction motors with the same output but different numbers of poles were simulated to calculate the voltage, current, and power using the parameters indicated on the nameplate, and to analyze the difference in power factor between them and select the optimal capacitor capacity to compensate for the insufficient power factor. As shown in the simulation results, when the number of poles is different even for motors with the same output, the magnitude of the active power and reactive power during starting and normal operation differs, and there is also a difference in the time it takes to reach the normal state.In addition, it was found that a larger capacitor is required to supply additional reactive power than a motor with a lower number of poles, because the power factor is lower when the number of poles is high even for the same capacity.

https://doi.org/10.5370/KIEE.2024.73.10.1757

김준혁(Jun-Hyeok Kim)

This study proposes a novel method for estimating tension in overhead wires of distribution systems using acceleration sensors, crucial for ensuring reliable power supply and proactive asset management. Traditional tension sensors, which are costly and complex to install, are replaced by a more cost-effective and robust alternative. Pearson correlation analysis revealed significant correlations between acceleration sensor data and actual wire tension, enabling the use of Gradient Boosting Regression(GBR) for effective tension estimation. The model achieved a high R2 score of 0.95, demonstrating the potential of acceleration sensor-based systems in maintaining system integrity and enabling real-time monitoring for preemptive maintenance. This method promises enhanced operational efficiency, system longevity, and cost savings. Future research should integrate these findings into comprehensive monitoring systems for improved decision-making.

https://doi.org/10.5370/KIEE.2024.73.10.1762

박병주(Byung-Ju Park) ; 최석근(Seok-Keun Choi)

The consumer power system in the steel industry is a representative high-power-consuming sector, characterized by predominantly nonlinear loads. Particularly, due to load characteristics that fluctuate irregularly over time, even with large-scale power receiving facilities, there is a high likelihood of power quality issues such as low power factor, flicker, imbalance, and the generation of integer and non-integer harmonics. The steel industry aims to enhance operational efficiency through power energy optimization, maintenance optimization, and productivity improvement, and to achieve this, securing stable power quality is essential. Based on this understanding, this paper addresses the current state of power quality in the industry through an analysis of actual measurements.

https://doi.org/10.5370/KIEE.2024.73.10.1768

함정수(Jung-Soo Ham) ; 권재화(Jae-Hwa Kwon) ; 민명환(Myung-Hwan Min) ; 안태풍(Tae-Pung An) ; 이태훈(Tae-Hoon Lee)

In the AC electric railway, reactive power is generated due to the inductive characteristics of the vehicle load and the capacitor bank. When the power system supplies reactive power, a penalty is incurred due to a low power factor. In addition, regenerative power is generated when braking a railroad vehicle, and electricity rates can be reduced if it is controlled and used as load power. This paper verifies the effectiveness through on-site test data that controls the reactive power generated when operating a railway vehicle through RPC, reduces the reactive power supplied by the power system, and controls the regenerative power and utilizes it as load power.

https://doi.org/10.5370/KIEE.2024.73.10.1774

윤치명(Chi-Myeong Yun) ; 김형철(Hyungchul Kim) ; 정호성진(Hosung Jung)

To achieve carbon emission reductions, minimizing electric energy consumption in railways is essential. Recent studies emphasize active substation control and vehicle load forecasting technologies, though research remains limited. Existing models for energy consumption often struggle with accuracy due to high load variability. This paper introduces a load forecasting method using the random forest model, demonstrating its superiority over Long Short-Term Memory (LSTM) methods, and proposes a technique for predicting substation power consumption based on these forecasts

https://doi.org/10.5370/KIEE.2024.73.10.1779

조환희(Hwan-Hee Cho) ; 김재원(Jae-Won Kim) ; 이한민(Han-Min Lee) ; 송민섭(Min-Sup Song)

This paper aims to stabilize substation voltage by using railway vehicles as voltage stabilization resources. By minimizing catenary voltage fluctuations, the stress on electrical components is reduced, and issues from overvoltage and overcurrent during train operation are mitigated. The research proposes a hybrid control structure combining model-based and data-based approaches, utilizing operation data. PSCAD-EMTDC and C language interface aided simulations shows the effectiveness of the control strategy in reducing voltage fluctuations and optimizing train operation patterns. This study offers a novel method for enhancing voltage stability and operational efficiency in railway systems.

https://doi.org/10.5370/KIEE.2024.73.10.1786

박종영(Jong-young Park) ; 권경빈(Kyung-bin Kwon) ; 홍수민(Sumin Hong) ; 황일서(Il-Seo Hwang) ; 허재행(Jae-Haeng Heo) ; 정호성(Hosung Jung)

This study addresses the challenge of managing fine dust (PM2.5 and PM10) levels in underground train stations, where air quality is compromised due to limited ventilation and various pollution sources. Traditional methods struggle to optimize control systems for dust reduction, particularly when accounting for station-specific variables like depth and congestion. To address this, the study proposes a machine learning-based energy management agent using a Deep Q-Network (DQN) integrated with an artificial neural network (ANN). The ANN predicts dust concentration changes based on fan and air conditioning controls, while the DQN optimizes these controls to balance dust reduction and energy costs. Additionally, the model considers the integration of photovoltaic power to enhance energy efficiency. The approach was validated using data from Namgwangju Station, demonstrating improved air quality and energy efficiency.

https://doi.org/10.5370/KIEE.2024.73.10.1794

김상암(Sang-Ahm Kim) ; 송은주(Eun-Ju Song)

This paper proposes an AI-based train approach detection algorithm designed for safety assistance systems aimed at reducing the increasing trend of accidents involving railway trackside workers. The proposed algorithm estimates optical flow using past and present images with a time difference, then detects trains in the current image using an object detection AI. It further utilizes radar data to acquire information on moving objects, combining these data to determine train approach. To validate the accuracy and reliability of the proposed algorithm, both laboratory and field tests were conducted, achieving a 100% detection rate in both daytime and nighttime conditions. The portable worker safety system incorporating this algorithm is expected to enhance the safety of trackside workers and contribute to the efficiency of railway maintenance operations.

https://doi.org/10.5370/KIEE.2024.73.10.1802

김진출(Jin-Chul Kim) ; 박하민(Ha-Min Park) ; 이주(Ju Lee) ; 이형우(Hyung-Woo Lee) ; 박찬배(Chan-Bae Park) ; 이재범(Jae-Bum Lee) ; 정광우(Kwang-Woo Chung)

Since the hydrogen electric tram operates based on hydrogen, a renewable energy source, a lot of research and development has recently been conducted at home and abroad. A high-density boost-type DC-DC converter that boosts the voltage of the hydrogen fuel cell is required between the hydrogen fuel cell and the inverter of the hydrogen electric tram. The interleaved boost converter is used as a conventional boost converter because it has a wide input/output voltage range, and operates with a phase difference for each module, allowing the volume of the capacitor and inductor to be reduced compared to a single boost converter. However, although the volume of the capacitor can be reduced, it is difficult to reduce the volume of the single module inductor, so there is a limitation that the volume of the entire converter system can be increased. Therefore, to solve this problem, this paper proposes to apply a coupled inductor to an interleaved boost converter.

https://doi.org/10.5370/KIEE.2024.73.10.1814

오용국(Yongkuk Oh) ; 류준형(Joonhyoung Ryu) ; 김재원(Jaewon Kim) ; 이형철(Hyeongcheol Lee)

This paper presents an energy management strategy for hydrogen fuel cell railway vehicles equipped with a Hybrid Energy Storage System (HESS). The proposed strategy aims to optimize power distribution between the hydrogen fuel cell and the HESS components, which include a battery system and ultracapacitor, in order to minimize hydrogen consumption and enhance system efficiency under various operating conditions. By employing the Equivalent Consumption Minimization Strategy (ECMS) and adjusting the power allocation based on the vehicle's power demands, the strategy effectively manages the state of charge (SOC) of both the battery system and ultracapacitor. Simulation results demonstrate that the proposed algorithm improves the hydrogen consumption by approximately 20% compared to conventional rule-based algorithms while maintaining a higher battery SOC. Also the proposed energy management strategy not only improves fuel efficiency but also contributes to the extended lifespan of the battery system by prioritizing the use of ultracapacitor for high-frequency power demands. This research offers a valuable approach for enhancing the performance and efficiency of hydrogen fuel cell railway systems, making a significant contribution to the development of eco-friendly rail transport technology.

https://doi.org/10.5370/KIEE.2024.73.10.1822

지우영(Woo-Young Ji) ; 오형석(Hyeong-Seok Oh) ; 이주(Ju Lee) ; 고태훈(Tae-Hoon Koh) ; 이형우(Hyeong-Woo Lee)

Various studies have been conducted to remove contaminants for the purpose of cleaning and/or reusing infrastructure such as contaminated soil, gravel, and wooden ties generated by railroads, and among them, the thermal desorption method has the advantage of high efficiency in removing contaminants by decomposing and evaporating contaminants at high temperatures. The thermal desorption method requires heating up to a high temperature of up to 700 , so induction heating is more suitable than ℃ heating using fuel. In addition, a proper design considering both thermal and electronic systems is required to ensure temperature safety to prevent burnout of the induction coil and efficient energy transfer. This paper introduces a thermal desorption decomposition system, and analyzes and designs using thermal/electronic system analysis and performance analysis through manufacturing and experiments.

https://doi.org/10.5370/KIEE.2024.73.10.1832

권용(Yong Kwon) ; 창상훈(Sang-Hoon Chang)

The mainline railway train control system can be classified into automatic train stop and automatic train protection. Automatic Train Protection (ATP) has been introduced and operated on mainline railways in Korea since 2003. The Lineside Electronic Unit(LEU) is one of the on-site ground facilities installed in block sections and is responsible for transmitting train control information through the Balise. It is designed to transmit train control information based on signal indication information on the block section track. However, in Korea, the LEU and Balise are connected by a solid line, so that uplink data can only control short distances. In the event of a malfunction or inspection at a block section track, maintenance personnel must arrive at the site and perform the work directly on the trackside. This causes a delay in the movement of personnel to ensure normal functioning, and in the case of sections where trains are in operation, safety issues may arise, and work efficiency may decrease. In this paper, we present the results of a test analysis of a control device developed to enable remote control and monitoring of ground-based equipment, such as Balise. This development device can transmit ‘Interface-C’, which acts as an up-link interface between the lineside control unit (LEU) and Balise among ETCS Level-1 on-board signal device, over long distances.

https://doi.org/10.5370/KIEE.2024.73.10.1840

박종빈(Jong-Bin Park) ; 정형근(Houng-Kun Joeng)

This paper investigates the design for improving the efficiency of the electromagnetic coil used in Non-Evaporator Getter (NEG) coating. For the proposed NEG coating, we design a solenoid-type coil shape, which is commonly used and focuses on forming a high-density magnetic field inside. We propose a design method for an electromagnet that forms a magnetic field of at least 100 Gauss within a radius of 10 mm from the maximum center point inside the coil. For the research presented in this paper, we use the finite element analysis software Ansys Maxwell to design and analyze the model, derive optimal parameters, and verify the results through simulations.

https://doi.org/10.5370/KIEE.2024.73.10.1846

박수민(Su-Min Park) ; 이현재(Hyun-Jae Lee) ; 박훈양(Hun-Yang Park) ; 손진근(Jin-Geun Shon)

This paper compares and validates the effectiveness of different control strategies for the inverter structure within a serial-type hybrid active power filter in compensating for harmonics efficiently, particularly in locations predominantly utilizing loads such as residential buildings. While hybrid active power filters are utilized to compensate for such harmonics, ineffective utilization of the inverter structure and control strategies within it may result in ineffective compensation for harmonics in loads. As a result, it was observed that simultaneous application of the 3-leg 4-wire inverter structure and DQO transformation effectively attenuated harmonic currents of all orders, including multiples of 3, demonstrating efficient compensation for harmonics.

https://doi.org/10.5370/KIEE.2024.73.10.1853

전동훈(Dong-Hoon Jeon) ; 김동일(Dong-Il Kim) ; 전병영(Byung-Young Chun) ; 김종석(Jong-Seok Kim) ; 문상필(Sang-Pil Mun) ; 우경일(Kyung-Il Woo)

An isolated modular boost converter is proposed as one of the solutions to efficiently deliver power from low voltage renewable energy sources such as photovoltaic cells to a high voltage battery. The converter consists of multiple boost modules, each of which comprises a phase shifted full bridge converter, a transformer and a diode rectifier. Both high boost ratio and high efficiency are achieved by connecting the output of the boost modules in series. The fundamental characteristics of the converter are demonstrated. In addition, parallel boost modules operation with imbalanced output power is proposed for further efficiency improvement. It is experimentally confirmed that the proposed power unbalancing scheme between two parallel boost modules improves the efficiency over wide operating ranges without any drawbacks.

https://doi.org/10.5370/KIEE.2024.73.10.1864

정재원(Jai-Won Chung) ; 방석오(Seok-oh Bang)

In this paper, we propose the random forest model for prediction of the preferred color temperature of lighting user using usage environment data. Temperature, relative humidity, precipitation, wind speed, hour, AM/PM status, day of the week, weekday/weekend status, and color temperature setting were measured at one hour interval through theanthropism experiment, and the relation of each variable were investigated through the correlation coefficient. Random forest models were established using the 5-fold cross validation method, with approximately 80% of the total data (n = 231) as the training set (n = 184). The model performances were evaluated using the test set (n = 47), which accounts for approximately 20% of all the data. The random forest models could predict the preferred color temperature with a maximum accuracy of 74.5% using hour and temperature.