https://doi.org/10.6110/KJACR.2025.37.1.1

Jong Hyeok Ryu ; Seok Kwon Jeong

This study presents the design of active disturbance rejection control (ADRC) to achieve robust control in the face of disturbances and model uncertainties in a variable speed refrigeration system. The proposed method involves estimating disturbances affecting the system through the design of an extended state observer and careful selection of observer gains. To minimize noise, the estimated disturbances are filtered using a low-pass filter before being integrated into the control input. Importantly, this study employs a genetic algorithm to select the eigenvalues of the system that determine the observer gains. Simulations and experiments conducted using Matlab/Simulink validate the effectiveness of ADRC by confirming the consistency between the results obtained from both approaches. The control performance of the proportional-integral (PI) controller enhanced by ADRC is analyzed in comparison to that of the PI controller alone. Lastly, the robustness of ADRC against model uncertainties is demonstrated through simulations that vary the characteristic parameters associated with model uncertainty and assess the resulting control performance.

https://doi.org/10.6110/KJACR.2025.37.1.13

Tae Ha Leigh ; Sang Ha Leigh ; Hyu San Jang ; Chan Kyu Kim ; SeungH yo Baek ; Myoung Souk Yeo

Traditional building-integrated solar thermal systems (BIST) often face challenges such as high costs, design constraints, and glare, which limit their widespread adoption. To address these issues, this study proposes a novel building-integrated solar thermal system called the Black Wall (BW), which enhances energy efficiency by utilizing capillary tubes without glass covers. Since existing energy simulation programs, such as EnergyPlus and TRNSYS, do not offer models suitable for analyzing the BW system, it was necessary to develop a refined model. A mathematical model, based on RC networks and the fin method, was created to simulate the thermal performance of the BW system. The simulation model was validated by comparing its results with experimental data collected from a test installation. The validation results showed a normalized root mean square error (nRMSE) of 11%, indicating a high level of accuracy in the simulation model. The BW system achieved approximately 40% heat gain efficiency, comparable to GLST systems, while offering advantages in design flexibility and ease of installation. This research demonstrates the potential of the BW system as a viable solar thermal collector, with future studies focusing on its integration with heating systems.

https://doi.org/10.6110/KJACR.2025.37.1.22

Hosang Ahn ; Suin Lee ; Jae Sik Kang

Digital conversion aimed at optimizing building energy usage has progressed since several building energy modeling tools, such as EnergyPlus and TRNSYS, became widely used. These programs can be considered an early stage of digital conversion in modeling buildings digitally to simulate energy usage. For optimizing building energy consumption, green remodeling is essential for enhancing building properties through both passive and active methods. Nowadays, digital tools for designing and constructing new buildings have garnered significant interest, as working with these tools can minimize repetitive modifications during the design process, thereby reducing unwanted time and cost. Among these digital tools, the IFC-BIM platform offers distinct advantages as a common resource for advancing new green remodeling processes. It can reflect and connect various parameters and open-source data more effectively than other commercial programs. In this study, the IFC-BIM structure of the green remodeling digital platform will be explored in conjunction with digital twin technology, considering the connectivity between these two platforms in the context of reducing and managing building energy usage to achieve carbon neutrality in the building sector.

https://doi.org/10.6110/KJACR.2025.37.1.35

Wangje Lee ; Youngsub An ; Hongjin Joo ; Jongkyu Kim ; Deukwon Kim ,Minhwi Kim ;

This study evaluates the thermal and electrical performance of roofless building-integrated photovoltaic and thermal (BIPVT) systems, focusing on three liquid collector systems. A full-scale mock-up simulating a curtain wall structure was developed to test these systems. The three BIPVT configurations are as follows Case (2) incorporates manifolds and plate heat pipes in contact with the tubes, and Case (3) uses manifolds and plate heat pipes in direct contact through a perforated structure. The thermal efficiencies ranged from 21.2% to 32% for Case (1), 7.6% to 13.6% for Case (2), and 3.7% to 9.4% for Case (3). The combined efficiency, including electrical power, was highest for Case (1) at 34.8%, followed by Case (2) at 19.8% and Case (3) at 17.2%. These results indicate that Case (1) provided the most effective heat collection and power generation, attributed to the larger heat transfer area of the absorber mechanism compared to the heat pipe. Overall, this study demonstrates that BIPVT systems, especially Case (1), offer significant potential for improving the energy efficiency of buildings. However, Case (2) provides advantages for building integration by eliminating the panel-to-panel joints on the building facade, which significantly reduces the risk of leakage. Case (2) is also a viable option for enhancing energy efficiency in buildings, particularly in terms of long-term structural integrity and maintenance.

https://doi.org/10.6110/KJACR.2025.37.1.43

Jae Yeob Song ; Sang Gon Choi

In this simulation study, the occurrence of an electric vehicle fire in a medium-to-large underground parking facility was analyzed through various simulated scenarios reflecting the operation of existing designed and constructed facilities. The study focused on the resulting fire characteristics, smoke distribution, and toxic gas dispersion. The findings indicate that when ventilation equipment is utilized as smoke control apparatus, the concentration of toxic gases within the parking area can exceed twice the lethal level. At a height of 1.5 meters, visibility diminishes to near zero in approximately 900 seconds. At the nearest point (point 6), visibility drops to near zero in about 100 seconds, while at the central point (point 1), it declines to near zero between 200 and 300 seconds. Even at point 4, the most distant location, visibility decreases to near zero within approximately 500 to 600 seconds, demonstrating that the parking facility examined in this study is ineffective in smoke removal. Although the peak concentration of toxic gases is reduced, the time until this peak is reached is prolonged. Notably, at point 5, the concentration remains below 30 ppm throughout the duration of the simulation, indicating that sprinklers have a fire control function in electric vehicle incidents, and ventilation systems also serve to mitigate toxic gas concentrations. Consequently, additional research is warranted to identify appropriate improvements, and it is imperative that relevant laws and regulations be developed and implemented promptly.