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272 results on '"Chang, Sung-Jin"'

11. Experimental Study on the Acceleration Amplification Ratio of Cable Terminations for Electric Power Facilities.

Author

Jeon, Bub-Gyu, Chang, Sung-Jin, Kim, Sung-Wan, Park, Dong-Uk, and Chun, Nakhyun

Subjects
*SHAKING table tests, *ELECTRIC cables, *FIBER-reinforced plastics, *ELECTRIC power, *BUSHINGS
Abstract

Among national infrastructure facilities, electric power facilities are very important sites that must maintain their functions properly even during a natural disaster or during social crises. Therefore, seismic design is required when necessary for major electric power facilities that have a significant impact when damaged in the event of an earthquake. In electric power facilities, bushings are generally installed in devices or structures. Therefore, ground acceleration can be amplified through devices, such as transformers, or sub-structures. Among various electric power facilities, cable terminations are representative cantilever-type substation facilities consisting of a bushing, a sub-structure, and support insulators. The bushings of cable terminations are generally made of porcelain or fiber-reinforced plastic (FRP) materials, and they may have different dynamic characteristics. This study attempted to estimate the acceleration amplification ratio in the main positions of cable terminations considering the materials of bushings. For two cable terminations with different specifications and bushing materials, three-axis shake table tests were conducted in accordance with IEEE 693, which includes a seismic performance evaluation method for a power substation facility. The acceleration amplification ratios at the top of the bushing, mass center, and top of the support structure were estimated using the acceleration responses of each cable termination. They were then compared with the acceleration amplification factors presented in design standards. Consequently, the acceleration amplification ratio of cable termination with an FRP bushing was lower than that of the cable termination with a porcelain bushing. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Korean Bible women : their vital contribution to Korean Protestantism, 1895-1945

Author

Chang, Sung-Jin

Subjects
270
Abstract

The aim of the thesis is to describe and assess the contribution of chŏndo puin (Korean Bible Women) to the growth of Protestant Christianity in Korea during the second half of the 19th century (late Chosŏn period) to the end of the Japanese occupation of Korea in 1945. The thesis will question western missionary perceptions of the chŏndo puin, and challenge their ignorance in contemporary Korean historiography. It will demonstrate that chŏndo puin were active subjects in the development of Korean Protestant Christianity, rather than the passive objects of evangelism. The research seeks to bring into visibility the “micro-histories” of the chŏndo puin through a critical re-reading of missionary archives, and oral research. Part One provides a critical reconstruction of the cultural landscape from which the chŏndo puin emerged. Chapter One re-assesses the leadership roles that Korean women were able to exercise in traditional Korean society, and corrects missionary misperceptions that denigrated the image of Korean women. Chapter Two examines the interaction between American missionary women and chŏndo puin. Part Two examines the diverse roles that the chŏndo puin fulfilled in the growth of Protestant Christianity from 1895 to 1937-45 when they played an important role in resistance of Japanese military imposition of Shinto practices. Chapter Three features the contributions of puin kwonse (as the chŏndo puin were originally known) to the early development of Protestant Christian mission in Korea. Chapter Four analyses the roles that chŏndo puin played in the period of Protestant Christianity’s most rapid growth in Korea. Chapter Five widens the analysis to include the role of chŏndo puin in Korean society through education and medical institutions, organisations of social outreach, and social-political movements for and against Japanese occupation. The main argument of the thesis is that the chŏndo puin were creative agents of mission in the development of the Protestant Church in Korea, and that their significance has been neglected or ignored in Korean Protestant historiography under the influence of western missionary and Korean male perspectives.

Published
2006

24. Proposed Commutation Method for Performance Improvement of Brushless DC Motor

Author

Chang-Sung Jin, Chang-Min Kim, In-Jin Kim, and Iksang Jang

Subjects
BLDC, commutation method, efficiency improvement, current harmonics, reduction acoustic noise, Technology
Abstract

This study focused on the efficiency improvement and acoustic noise reduction of brushless DC (BLDC) motors by reducing current harmonics using a novel BLDC commutation method. To achieve these goals, we designed an improved 150° commutation method for a three-phase permanent magnet BLDC motor that can improve the current waveform. Although the 120° commutation method is generally employed for BLDC motors, an improved 150° commutation method is introduced to operate the BLDC with increased efficiency and acoustic noise similar to a brushless AC motor. This study investigated the attributes of various commutation methods, both theoretically and experimentally, to determine the optimal commutation method. The results of this study indicate that the improved 150° commutation method is optimal in terms of harmonic attributes and reduced torque ripple, allowing it to improve motor efficiency and reduce acoustic noise.

Published
2021
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28. Study on the Design of Six-Phase Surface Inset Permanent Magnet Synchronous Generator and Motor Considering the Power Factor and Torque Ripple

Author

Seungtaek Oh, Chang-Sung Jin, Yeji Park, Ju Lee, Won Ho Kim, and Hyunwoo Kim

Subjects
Surface (mathematics), Materials science, Control theory, Phase (waves), Power factor, Permanent magnet synchronous generator, Torque ripple, Electrical and Electronic Engineering, Electronic, Optical and Magnetic Materials
Published
2022
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29. Science of Water at Nanoscale

Author

Chang, Sung-Jin, Jhe, Wonho, Park, Gun-Sik, editor, Kim, Yong Hyup, editor, Han, Haewook, editor, Han, Joon Koo, editor, Ahn, Jaewook, editor, Son, Joo-Hiuk, editor, Park, Woong-Yang, editor, and Jeong, Young Uk, editor

Published
2012
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46. Optimal Design of an Ultra-Premium-Efficiency PMA-Synchronous Reluctance Motor With the Winding Method and Stator Parameters to Reduce Flux Leakage and Minimize Torque Pulsations

Author

Kyoung-Jin Joo, Ye Jun Oh, Ju Lee, Ho-Joon Lee, Hyun-Soo Seol, Huai-Cong Liu, Won-Ho Kim, and Chang-Sung Jin Jin

Subjects
010302 applied physics, Optimal design, Stator, Computer science, 020208 electrical & electronic engineering, Flux, Premium efficiency, 02 engineering and technology, 01 natural sciences, Finite element method, Electronic, Optical and Magnetic Materials, law.invention, law, Control theory, Electromagnetic coil, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Torque, Torque ripple, Electrical and Electronic Engineering, Maximum torque, Leakage (electronics)
Abstract

In this paper, the optimal design for a permanent magnet-assisted synchronous reluctance motor (PMA-SynRM) is proposed in terms of efficiency, maximum torque, and minimum torque pulsations. Design variables, objective functions, and constraints are selected for this optimal design, which is divided into two steps. Step I utilizes the pole/slot combination of the PMA-SynRM and winding methods. The chosen 4-pole/36-slot model with distributed winding maximizes the rated efficiency. In Step II, the optimal design of the stator parameters is obtained using the response surface method and the precise torque and torque ripple are calculated using the finite-element analysis (FEA). The proposed stator slot openings are minimized to minimize the air-gap flux leakage, and consequently, realize a smooth electromagnetic torque. Finally, a few FEA results are validated by experimental results.

Published
2018
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