https://doi.org/10.5370/KIEE.2024.73.4.655

조혜원(Hye-Won Jo) ; 송유훈(Yu-Hoon Song) ; 국경수(Kyung-Soo Kook)

As the penetration of RES is increasing rapidly to reduce the green house gas emission, there are concerns that the variability of RES, which is highly weather-dependent, would amplify the variability of the power system in terms of balancing electricity supply and demand. A frequency regulating reserve has been operated to respond to such variability in the power system and its requirements is calculated by analysing the history data of the electiricity demand. However, existing methods do not consider variability of RES, which should be estimated considering the expansion plan of RES for the future power system. In this paper, a method is proposed to calculate the frequency regulating reserve requirements of the power system with a high penetration level of RES. For doing this, the variabilities of electricity demand and RES respectively derived from those history data are projected to the future power system, and the required amount of the frequency regulating reserve is statistically calculated to respond those variabilities. The effectiveness of the proposed method is verified through study cases employing Korean power system developed for the basic plan of long-term electricity supply and demand.

https://doi.org/10.5370/KIEE.2024.73.4.662

전승찬(Seungchan Jeon) ; 배성우(Sungwoo Bae)

This paper proposes a Lyapunov optimization-based EMS (Energy Management System) algorithm aimed at improving the economic and stability of micro-grid. The proposed algorithm introduces a virtual queue to model the impact of ESS (Energy Storage System) charge/discharge cycles on its lifespan. Formulated as a Lyapunov-based optimization problem using the Drift-Plus-Penalty method, the algorithm controls a balance between micro-grid operating costs and ESS lifespan stability. The proposed algorithm was validated using real data from solar, wind, and demand resources in Jeju Island, to demonstrate its performance in a resource-variable micro-grid environment. Results showed that by adjusting a single parameter V, the proposed algorithm offers flexible control for managing operating costs and ESS lifespan stability aligned with the operator's objectives. The proposed algorithm overperforms in terms of both micro-grid operating costs and ESS lifespan stability against conventional algorithms, achieving a 99.99% energy balance satisfaction rate index. Moreover, the proposed algorithm guarantees the stable operation of multi-ESS units amid the dynamic resource variability in the micro-grid, securing both economic efficiency and operational stability. Therefore, this research can contributes to the advancement of EMS, providing effective solutions for optimizing micro-grid operating cost and enhancing the longevity of ESS.

https://doi.org/10.5370/KIEE.2024.73.4.671

정범희(Beom-Hee Jeong) ; 김지안(Jian Kim) ; 심재성(Jae-Sung Sim) ; 정일엽(Il-Yop Chung)

In this paper, we propose generator scheduling method using load forecasting to improve the economic efficiency in electric propulsion ship. For efficient generator scheduling, we derive generator cost function using the generator specific fuel consumption (SFC) curves. Next, we classify the ship load into three categories such as propulsion load, service load, and pulse load. According to the load categories, we define the forecasting methods that are suitable for the load characteristics. Then, using the load forecasting results, the proposed generator scheduling algorithms determine the generator unit commitment to prevent repeated turn-on-and-off operations of the specific generators and calculate the generator economic dispatch using the generator fuel cost function. Through simulation case studies, we perform generator scheduling based on various combinations of different sizes of generators and ship operation scenarios. Based on the generator scheduling results, we calculate the total fuel cost and start-up cost, and we analysis an economic efficiency by comparing traditional generator scheduling and proposed generator scheduling method. We also analyze economic efficiency according to generator configuration in electric propulsion ship

https://doi.org/10.5370/KIEE.2024.73.4.682

윤한준(Han-Joon Yoon) ; 조재훈(Jae-Hoon Cho) ; 김용재(Yong-Jae Kim) ; 정상용(Sang-Yong Jung)

This paper researches the electromagnetic parameters of consequent-pole motors (CPMs) considering the rotor topology. First, the concept of electromagnetic parameter analysis is introduced. Second, the CPM is compared with the interior permanent magnet synchronous motors (IPMSMs), focusing the differences of the rotor topology characteristics. With the comparison, the proper rotor type is proposed. Third, we conducted an optimal design to improve the torque characteristics by applying an optimization algorithm. Finally, the demagnetization and stress characteristics are analyzed

https://doi.org/10.5370/KIEE.2024.73.4.690

전완수(Wan-Su Jeon) ; 박성희(Sung-Hee Park) ; 손주형(Joo-Hyeong Son) ; 박재준(Jae-Jun Park)

The international community's efforts to reduce greenhouse gases, a global environmental problem, are continuing, and as part of this effort, bio-epoxy resin, a sustainable and renewable resource, is emerging as an alternative. As part of this, research has begun to replace petrochemical epoxy resin used in heavy electric equipment for distribution and substation with bio-epoxy. Ten types of samples were prepared by mixing petrochemical epoxy DGEBA and bioepoxy ESBO in content ratio (phr). In addition, DGEBA/ESBO/M10_65wt% Mixture Composites 10 are used to replace insulation materials for heavy electric power distribution equipment. A variety of samples were prepared. Among the various properties, the most important electrical properties, AC dielectric breakdown strength and dielectric properties, were evaluated. Among the electrical insulation breakdown and dielectric properties, DGEBA:ESBO= 70phr:30phr and DGEBA:ESBO=70phr:30phr/M10_65wt% Composites had the potential for commercialization in heavy electric equipment for distribution.

https://doi.org/10.5370/KIEE.2024.73.4.700

고만석(Man-Suck Ko) ; 권현호(Hyun-Ho Kwon) ; 이진호(Jin-Ho Lee) ; 전상동(Sang-Dong Jeon) ; 김용현(Yong-Hyun Kim)

Combined Asset Health Index(CAHI) is presented to justify decisions such as replacement, repair, and additional inspection to reduce risks in the asset management system. CAHI evaluates the condition of assets using its purchase, installation, operation, visual inspection, off-line diagnosis and on-line monitoring data. CAHI identifies assets that are high risk of failure or deterioration based on the result of the asset condition. CAHI calculates condition index which represents the condition of the asset(Probability of Failure), and degradation index which represents the deterioration of the asset. Additionally, strategic index is calculated by applying the practice of replacement according to their operation age. Three indices are combined into worst case and presented as CAHI. CAHI was applied to 628 operating power transformers to evaluate its effectiveness. The condition index confirmed that each condition indicator independently indicates the probability of failure. The degradation index confirmed that asset management policies can be established by assigning weights to each degradation index based on an example in which high weight assigned to the type of insulating paper and oil preservation system. However, the condition index and degradation index did not increase and showed randomly as the operation age of the transformer increased. Therefore, strategic index is presented by applying the practice of preventive replacement according to operation age.

https://doi.org/10.5370/KIEE.2024.73.4.711

서경욱(Kyeong-Wook Seo) ; 황동윤(Dong-Yun Hwang) ; 이민호(Min-Ho Lee) ; 송진우(Jin-Woo Song) ; (Do Hoang Viet)

Indoor navigation stands out as a crucial technology for the smooth performance of robots. This paper proposes an algorithm for position estimation employing a monocular camera and an inertial measurement unit, presenting a system that re-estimates the robot’s position based on the localization of ArUco markers. The algorithm is designed based on the extended Kalman filter, utilizing measurements derived from the calculated position and velocity information obtained from the markers. Experimental validation of the proposed algorithm demonstrates its effectiveness, confirming the ability to estimate the robot’s position by randomly attaching markers in an environment without pre-set configurations.

https://doi.org/10.5370/KIEE.2024.73.4.718

강동운(Dongwoon Kang) ; 이주원(Juwon Lee) ; 김범수(Bumsu Kim) ; 한민규(Minkyu Han) ; 김진성(Jinsung Kim) ; 방재성(Jaesung Bang) ; 백주훈(Juhoon Back)

The model-based control technique requires an accurate system model identification process because the performance of the controller varies depending on the accuracy of the system model information. However, there is a limit to finding accurate model information of the system due to noise of measurement data or system disturbance. Recently, active research on data-based controllers has proposed a data-driven problem structure that can design a controller using only data without identifying a system model. In this paper, we propose a method for obtaining a coordinate transformation matrix that enables Kalman decomposition of a linear system within this data-driven problem structure. Using the pre-experimental data, we obtain the uncontrollable generalized left eigenvector and use it as a basis vector to span the uncontrollable subspace. Finally, the proposed algorithm was verified through an example with uncontrollable repeated eigenvalues.

https://doi.org/10.5370/KIEE.2024.73.4.725

채운(Woon Chae) ; 권순용(Soonyong Gwon) ; 서기성(Kisung Seo)

Person re-identification involves the task of identifying a specific person among multiple images obtained from different locations. Re-identifying individuals with complex clothing changes poses a greater challenge as clothing information, a key feature in conventional person re-identification, is altered. Attempts have been made to address this issue by either adding non-clothing features or excluding features related to clothing from training. However, such approaches have limitations in performance improvement as they exclude valid features of clothing. In contrast, this paper proposes a technique that utilizes valid features of clothing information through a color label-based branching structure model for re-identification. The proposed method is compared to the performance of state-of-the-art methods using the LTCC dataset, which consists of clothing change data. The results show superior performance based on Rank-1 and mAP metrics.

https://doi.org/10.5370/KIEE.2024.73.4.731

이해원(Hae-Won Lee) ; 최장영(Jang-Young Choi)

AC substation power quality tests are evaluated by measuring harmonics and voltage unbalanced under driving conditions of electric trains. Harmonics are measured up to the fundamental and 49th harmonics by connecting a power analyzer to the 154kV side busbars at the substation. During the test operation of the EMU260 and EL8500 on the newly built Daegu Line of the Yeongcheon Railway Substation, it was evaluated that 27th harmonic voltage% exceeded the standard in the harmonic measurement. In order to analyze the cause of exceeding the standard, all load CB on the Daegu Line were opened and measured, and it was confirmed that harmonic waves from power sources were already exceeding the standard. In this paper, when measuring the harmonic of a new electric railway substation, it is measured by considering the inflow from the power supply, the reasons why the standards should be judged or not and the improvement of the power quality test evaluation criteria were presented.

https://doi.org/10.5370/KIEE.2024.73.4.738

임태훈(Tae-Hoon Lim) ; 신화선(Hwa-Seon Shin) ; 하철우(Cheol-Woo Ha) ; 이혜인(Hye-In Lee)

This paper describes training data construction and analysis for developing a process-optimized artificial intelligence model to minimize errors occurring during the SLA-based additive manufacturing process. The photocurable resin molding method is a way in which UV lasers are irradiated into a tank containing liquid resin, solidified and stacked layer by layer, and like other additive manufacturing methods, there is an error in output deformation. However, due to the opaque resin, it is more difficult to check the error pattern than other method printer. In this study, to detect these error patterns, collecting data system in the actual process was established for sensor data, image data, and thermal image data and a study on data analysis was conducted

https://doi.org/10.5370/KIEE.2024.73.4.744

이훈서(Hunseo Lee) ; 강현일(Hyunil Kang) ; 정인철(In-Chul Jung) ; 박영(Young Park)

The initial verification of a new electrical installation is a critical step in ensuring its safety and reliability. By identifying and addressing any potential hazards or deficiencies, the initial verification can help to improve the overall quality of the installation. This paper proposes a new system for initial verification of electrical installations in Korea. The current practice of conducting on-site inspections is time-consuming and inefficient. Online inspections, on the other hand, can be more efficient and effective, and they have the potential to improve the safety and reliability of electrical installations. The introduction of an online inspection system can help to improve the efficiency and effectiveness of the initial verification process.

https://doi.org/10.5370/KIEE.2024.73.4.749

윤용호(Yong-Ho Yoon)

As the demand and field of use for lead acid batteries increases, interest in test methods and test facilities that consider the characteristics and safety of batteries is also increasing. Basically, there are problems related to the charging time, self-discharge, charging and discharging characteristics, and energy density (low energy density) of lead acid batteries. The charging and discharging characteristics of lead acid batteries are stable within a certain range, but excessive discharging or overcharging reduces performance and shortens lifespan, and repeated charging and discharging has a significant impact on changes in the characteristics and lifespan of the battery. When charging a lead acid battery, conditions such as voltage, current, time, and temperature are often within the range set by the battery specifications. And the discharge operation is directly related to the usage time and performance of the lead acid battery and is evaluated as its own performance factor. Therefore, due to the complex characteristics of lead acid batteries due to charging and discharging, research on optimization and management is needed in various ways. Therefore, in this paper, we built a test facility that can analyze the charging and discharging characteristics of lead acid batteries. And using these test facilities, we aim to promote the safety of lead-acid batteries by analyzing their operation and analysis through charging and discharging experiments.