http://doi.org/10.5207/JIEIE.2025.39.1.1

Kyoung-Ho Oh ; Kyeong-Wan Jeon ; Byoung-Duk Park

By applying the standard e-IoT (Energy IoT) protocol established by KEPCO, we proposed a system for the remote control and monitoring of public lighting and designed and manufactured a device to verify its functionality. To achieve this, we analyzed the e-IoT protocol based on the e-IoT standard document, Internet of Things Information Modeling and Linkage Rules. Furthermore, using the LwM2M IPSO system, we defined the objects and resources for lighting on/off and dimming control, and implemented the communication interface. The proposed system was designed using Eclipse Leshan and verified through testing with Postman. In the future, if this system is introduced into a public lighting monitoring and control system based on IoT standards, it will enable interoperability technology for public lighting systems deployed by operating entities.

http://doi.org/10.5207/JIEIE.2025.39.1.8

Sang-Bin Song ; Sang-Yoo Kim ; Eun-Ji Kim ; Ji-Myung Kim

In this paper, we selected eight sensors(CO, CO2, O2, smoke, temperature, humidity, vibration, infrared, etc.) suitable for underground utility tunnel in korea based on the shape of the building, the arrangement of facilities, the condition of the enclosure, and the materials of power lines and facilities. We designed a multi-sensor module with a SIP (System In Package) structure to integrate and embed the eight selected sensors, a signal processing algorithm that considers the response time characteristics between multiple sensors, and a third-order Butter-worth low-pass filter to remove noise errors in the DC component of the output signal. In addition, we designed the enclosure structure by conducting flow simulation (Solidwork simulation program), manufactured a prototype, and applied leveling technology to improve the accuracy of the multi-sensor based on the data measured in the test bed. As a result, it was confirmed that it was possible to detect whether a fire occurred within 30 seconds in the event of a fire, except for the CO2 sensor, and the fire detection reliability showed a high performance of about 95% or more. After installing 55 complex environmental sensors integrated with lighting fixtures in the Ochang Underground Utility Tunnel(about 750m underground common area distance), we evaluated the sensing data transmission characteristics and the accuracy of the sensing data delivered to the SPU and DCU and the sensor values displayed in the related systems to prove its excellence.

http://doi.org/10.5207/JIEIE.2025.39.1.16

Eun-Ji Kim ; Ga-Young Ryu ; Ji-Su Pyo ; Sang-Bin Song ; Jae-Yong Joo

This paper presents a design approach for outdoor advertising displays based on Electronic Paper Display (EPD) technology, which enables ultra-low power operation. As the demand for outdoor advertising displays rapidly increases, the need for high-performance displays capable of operating in extreme environments such as high temperatures and direct sunlight is growing. Traditional LCD displays face limitations in brightness and reliability, and to address these issues, this study focuses on EPD technology. In this study, a system was designed to mount an EPD on a mobility device such as a bicycle to broadcast advertisements in real-time, and the feasibility of its implementation was experimentally examined. EPD displays offer low power consumption and excellent readability, achieving high brightness and uniformity to function effectively in outdoor environments. Furthermore, EPDs are capable of color image display, optical design for nighttime visibility, and exhibit excellent electromagnetic shielding performance, ensuring high reliability. This research demonstrates the potential of EPD displays as outdoor advertising displays in mobility-based environments and contributes to the design of energy-efficient advertising systems. In the future, the positive impact of EPD technology on the outdoor advertising industry and the development direction of related technologies will be analyzed.

http://doi.org/10.5207/JIEIE.2025.39.1.22

Won-Il Lee ; Ji-Su Kim ; Seung-Beom Lim

Energy efficiency technology for constant temperature-controlled logistics centers, which use a lot of power, is becoming a problem as the e-commerce market and logistics sector expand quickly. Several power conversion systems, including Low Voltage Direct Current (LVDC), Energy Storage System (ESS), and Uninterruptible Power Supply (UPS), can be set up as the center’s power devices for energy efficiency, power quality, emergency power supply, and distribution efficiency. Photovoltaic (PV) systems can also be used in light of the Renewable Electricity 100 (RE100) initiative, which intends to use all electricity from renewable energy sources by 2025. In order to address the issue of power loss that arises in numerous power conversion systems, we present in this work the creation of an integrated multi-power conversion system that combines PV, ESS, LVDC, and UPS.

http://doi.org/10.5207/JIEIE.2025.39.1.29

Hoon Jung ; Joon-Ho Ahn

This study aims to enhance the architectural model to improve interoperability in distributed energy-based microgrids. Although digitalization of power infrastructure has advanced with the adoption of smart grids, the absence of standards and technology for interoperability among various power networks and microgrids hinders optimal generation and trading. This paper proposes an interoperability architecture model tailored to Korean microgrid conditions, based on the IEC’s Smart Grid Architecture Model (SGAM). The proposed model aims to comprehensively manage the entire power network, from generation to consumption, with support for real-time monitoring and data exchange through the integration of IoT, ICT, and AI. This enhanced architecture not only facilitates power trading and efficient operation between microgrids but also enables a flexible power network configuration suited to Korea’s evolving electricity market and policy landscape.

http://doi.org/10.5207/JIEIE.2025.39.1.36

Do-Hee Kim ; Rae-Young Kim

In This study examines the estimation values and demand factors for load equipment, which are crucial for transformer sizing, by analyzing the standards applied in Korea and the United States. In Korea, these matters are subject to review by design enginers. Therefore, this study reviews the application, particularly focusing on the application methods for load equipment capacity estimation data and demand factor information in the NEC and IEEE standards. This study examines the standards of Korea and the United States, respectively. This study hope to contribute to the caculation of electrical load capacity and the application of demand factors in the future.

http://doi.org/10.5207/JIEIE.2025.39.1.44

Jae-Eun Hwang ; Yoon Hee Oh ; Byung O Kang ; Herie Park

This study proposes a methodology for performance evaluation of fault diagnosis in photovoltaic (PV) systems using machine learning techniques, including Random Forest, k-Nearest Neighbors (kNN), and Naive Bayes. Actual data were acquired from a 3kW PV testbed and categorized into eight classes representing normal and significant fault conditions. For each class, a confusion matrix and corresponding relevant metrics are utilized to conduct class-specific performance assessments. The results indicate that the Random Forest model outperforms other models in terms of accuracy, precision, recall, and F1 score. It demonstrates outstanding performance for normal conditions (Class 0 and Class 7) and maintains stable performance for major fault types (Class 1 and Class 6). While the kNN model delivers acceptable performance for Class 0, it shows limitations for certain fault types. The Naive Bayes model exhibits the lowest performance and faces significant challenges in accurately handling most fault types.

http://doi.org/10.5207/JIEIE.2025.39.1.52

Sung-Min Park ; Chul-Won Park

Pumped Storage Hydropower is one of the large-scale Energy Storage System that is economical to ensure the stability of power grid and to supply the power demand smoothly. When large-scale RES is supplied to the metropolitan area, transmission constraints and transmission congestion may occur. Therefore, by linking the construction of power plants to high-load demand areas in order to minimize transmission congestion and transmission network construction, problems caused by the transmission network can be alleviated. In this paper, we propose Distribution Pumped Storage Power Plants (DPSP) that do not require lower reservoirs around existing multipurpose hydroelectric power plant dams in terms of role diversification of hydroelectric power plants. In order to analyze the validity of the proposed DPSP and evaluate the value of the investment plan, an economic analysis is performed using Net Present Value (NPV) and Benefit Cost (B/C). As a result of analyzing KHNP’s cost and profit data by applying them to the 3GW ratio, when the operating period was 30 years and the discount rate was 4.5%, NPV was analyzed as -427.3 billion won and B/C was 0.396 in 2019. In addition, when the operating period was 40 years and the discount rate was 4.5%, NPV was -44,521 billion won and B/C was 0.431.

http://doi.org/10.5207/JIEIE.2025.39.1.59

Young-Lak Kim ; Chun-Hyung Cho

This study proposes a method to address issues that may arise during the linearization process of a high-power amplifier (HPA) used in TDD-based communication equipment and to protect the device. When operating digital predistortion (DPD) or performing frequency alignment (FA), noise peaks can enter the HPA together with the RF control output signal, creating transient over-input signals. These excessive input levels can potentially destroy the main transistor (TR), which is the core component of the HPA. However, this research demonstrates that such damage can be prevented. Experimental tests conducted on a standalone module showed that over-input signals could be about 10dB higher than the control output signal, and at these high input levels, the main TR was found to be damaged. To protect the device, a peak limiter was applied, reducing the over-input signal by 15dB. In other words, although the over-input signal was originally 10dB above the control output, after passing through the peak limiter, it became 5dB below the control output. This confirms that the over-input signal was sufficiently mitigated. Furthermore, a protective comparison test was conducted by applying the method to an actual HPA. Under an over-input condition, the circuit output was reduced by more than 20dBm, thereby lowering the level of the signal entering the HPA’s main TR and effectively protecting it.

http://doi.org/10.5207/JIEIE.2025.39.1.65

Herie Park ; Jae-Eun Hwang ; Sanghyo Kim ; Su-Ho Lee

This study aims to analyze the electric field characteristics of encapsulation materials used in power semiconductor packages and propose optimal insulation design techniques. The research focuses on mitigating electric field concentration at the triple junction, a critical structural vulnerability where metal electrodes, ceramic substrates, and encapsulation materials meet. Simulations were conducted using COMSOL Multiphysics to evaluate the effects of various encapsulation materials, including epoxy compound, silicone gel, PDMS, and graphene nanofiller composites. Key design variables such as electrode spacing and substrate thickness were adjusted to assess their impact on electric field distribution and insulation performance. The results indicate that silicone gel demonstrates high dielectric strength and effectively mitigates electric field concentration near the triple junction. A comparison of encapsulation materials: epoxy compound, silicone gel, and PDMS revealed distinct insulation and electric field distribution characteristics, with the order of electric field concentration increasing as PDMS < silicone gel < epoxy compound. Although graphene nanofiller-enhanced epoxy was introduced to improve electrical conductivity and composite properties, it exhibited a tendency to increase electric field concentration near the triple junction.

http://doi.org/10.5207/JIEIE.2025.39.1.71

Hobin Lee ; Bonhyuk Ku ; Hyoungku Kang

HVDC (High Voltage Direct Current) transmission systems are efficient for long-distance, high-capacity power transfer and asynchronous network interconnection. However, insulation design is challenging due to localized polarization and space charge effects in steady-state conditions, and high electrical stress in transient conditions. This study focuses on designing corona rings for 500kV HVDC transmission systems, addressing all electrical stresses encountered under both steady-state and transient-state to enhance insulation reliability. Using COMSOL Multiphysics, three key corona ring parameters were optimized to mitigate electrical stresses. Finite element analysis showed maximum electric fields were concentrated near metal fittings and sheds under steady-state conditions, and at the triple junctions under transient-state. Before corona ring installation, safety factors were critically low at 0.5 in steady-state and 0.1 in transient conditions. The optimized corona ring increased safetyfactors to 2.5 and 3.3 in steady-state, and 1.3 and 1.2 in transient-state. These results demonstrate the optimized corona ring effectively mitigates electric field concentrations, enhances safetyfactors, and extends the operational life of polymer insulators, ensuring reliability under extreme conditions.

http://doi.org/10.5207/JIEIE.2025.39.1.77

Hoon Jung ; Jong-Chan Lee ; Joon-Ho Ahn

In the process of energy transition, the importance of distributed energy resources (DERs) has been growing, as they enable more flexible and efficient power supply compared to traditional centralized power grids. In South Korea, the Distributed Energy Resources Activation Special Act was enacted to promote the utilization of DERs, ensure the stability of the power supply system, and facilitate the activation of power trading among distributed resources. To enable active power trading among various microgrids, technical, regulatory, and economic factors must be addressed. Above all, achieving interoperability a crucial element in energy self-sufficient power trading?is essential. This paper presents a data map to ensure platform compatibility in distributed energy resource power trading. Based on this framework, it examines the feasibility of data communication between heterogeneous protocols to secure interoperability at the platform level, which manages regional microgrids.