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최성대(SEONGDAE CHOI),금동진(DONGJIN GEUM) 대한전기학회 2019 대한전기학회 학술대회 논문집 Vol.2019 No.5
전기차 보급확대는 세계적 트랜드로 우리정부 역시 구매보조금의 지급과 함께 충전인프라의 보급정책을 시행하고 있다. 전기차의 증가는 전력판매의 증가로 이어져 전력수요의 증가가 정체되어 있는 시기에 전기차의 보급확대는 전력 유틸리티의 수익을 높이는 가장 효과적인 방법이라 할 수 있다. 충전인프라의 구축이 전기차의 증가에 효과가 있는지에 대한 연구가 전무하여 전력수요 창출이 수익과 직결됨과 동시에 충전인프라 구축을 담당하고 있는 전력 유틸리티 입장에서는 이에 대한 점검이 필요하다. 이를 위해 “전기차 충전인프라 구축은 전기차 보급에 긍정적인 영향을 미치고 있다.”와 “공용 충전인프라의 보급이 홈 충전인프라의 보급보다 전기차 보급에 긍정적인 영향을 미치고 있다.”라는 두 가설을 수립하여 회귀분석을 통해 검증한 결과, 두 가설은 모두 타당한 것으로 검토되었다. 회귀분석은 충전인프라 및 전기차 증가외 유가증가, 가구당 차량수, 전체 차량 수를 각각 독립변수로 설정하는 다중 회귀분석을 통해 검증하여 복합적인 환경을 고려하였다. 충전인프라 중 공용 충전인프라의 확충은 전기차 보급확대에 긍정적인 효과를 나타내고 있어, 공용 충전인프라 확충은 전력 유틸리티의 수익을 증가시키는 방법임을 알 수 있다.
최현진(Hyunjin Choi),박철우(Chulwoo Park),박철휴(Chulhue Park),이종철(Jongcheol Lee),김종갑(Jonggab Kim),최성대(Seongdae Choi) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The most important properties of the automotive engine seal are the low friction and the abrasion resistance. In order to strengthen these properties, the two types of seal are developed and analyzed. One seal is made by mixing the PTFE and the glass fiber and the other is made by mixing the PTFE, the glass fiber and the molybdenum. The analysis of the stress and the reaction force are carried out using the shape design of seal, which is mounted on the front part of the automotive engine. We analyzed the maximum stress and the contact weight of PTFE lip part and then made the two types of PTFE seal. Finally, we evaluated the stress concentration and the abrasion resistance through the coefficient of friction and torque and endurance test.
Design Parameter Analysis of a Dynamic Absorber for the Control of Machine Body Vibration
Giman Kim(김기만),Seongdae Choi(최성대) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.1
The optimal design parameters of a dynamic absorber (DA) in a machine body (that is considered as a rigid body) are discussed in this paper. The bounce and rotation motions of the rigid body have been controlled passively by a DA, which consists of a mass and a spring. The rigid body is subjected to a harmonically excited force and supported by linear springs at both ends. To define the motion of a rigid body with a DA, the equation of motion was expressed in the third-order matrix form. To define the optimal design conditions of a DA, the reduction of dynamic characteristics, represented by the amplitudes of bounce and rotation, and the transmitted powers, were evaluated and discussed. The level of reduction was found to be highly dependent on the location and spring stiffness of the DA.
Reduction of Vibration for an Elastic Structure by means of a Relocation of Part
Giman Kim(김기만),Seongdae Choi(최성대) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.7
This study deals with the passive control of the dynamic characteristics of a theoretical model which is a string with fixed ends and loaded by two point masses - a main mass (Mo) and a secondary mass (Ms). It has been controlled passively by means of a relocation of a secondary mass. A main mass placed on the string is considered as a vibrating receiver which be forced to vibrate by a vibrating source being positioned on the string. By analyzing the motion of a string, the equation of motion for a string was derived by using a method of variation of parameters. To define the optimal conditions for the vibration reduction, the governing equation, which denotes the dynamic response of a string was derived in the closed form and then evaluated numerically. The possibility of reduction of an amplitude and a power being transmitted to a main mass were found to depend on the location and the magnitude of a secondary mass as well as the range of a forcing frequency.