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신창우(Chang Woo Shin),정종렬(Jong Ryeol Jeong),임원식(Won Sik Lim),차석원(Suk Won Cha) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
There is a big difference between electric vehicles(EVs) and conventional vehicles in the construction and power flow of the powertrain. Therefore, whenever someone develops an EV, they should take into consideration improvement of dynamic performance in EVs. In this paper, we conducted a research on a design method to determine the traction motor characteristics and the final reduction gear ratio in the electric bus, which consists of a motor, a battery system and a final reduction gear. We analyzed the required motor power of the electric bus based upon the maximum vehicle speed needed and the grading performance of the vehicle. This paper proposed a design method for the optimal final reduction gear ratio to satisfy vehicle acceleration performance by using a motor efficiency according to the driving cycles. By using the determined motor performance and the optimal gear ratio, backward simulation was conducted to confirm a variation of SOC(state of charge) for city bus driving cycles.
자유 음장 조건에서 개선된 빔형성 방법을 이용한 흡음재의 수직 입사 표면 임피던스 측정
신창우(Shin, Chang-Woo),선종천(Sun, Jong-Choen),강연준(Kang, Yeon-June),백순권(Paik, Soon-Kwon) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.6
An improved beamforming method is proposed to measure the surface impedance of absorbing materials in a free field. It is possible to estimate the surface impedance by decomposing measured signals into incident and reflected signals by using the spatial filter matrix of the beamforming method. Wavelet do-noising techniques which reduce the white Gaussian noise are applied to improve the results. Phase calibration method is also used to improve the results of the measured surface impedance in a low frequency range. The results of the normal incidence experiments that are performed in a semi-anechoic chamber are verified by comparing with those of the standard test method that is presented in ASTM E1050. The proposed method is found to be reliable to measure the surface impedance for frequencies higher than 400 Hz.
신창우(Chang Woo Shin),김형균(Hyungkyoon Kim),김문겸(Mun Kyum Kim),임원식(Wonsik Lim),차석원(Sukwon Cha) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
A drivability of vehicles means subjective perception for dynamic performance and comfort of a vehicle in response to driver input. Subjective evaluations by experienced test driver have been primarily used to assess the drivability in automotive companies. These evaluations are limited in repeatability and require much time and cost. In this paper, vehicle test was conducted to measure data for objective drivability evaluations in heavy duty vehicles. The evaluation indices for drivability were selected from references, which are related to ride comfort and objective evaluation of drivability, according to operation conditions. The quantitative evaluation method was proposed by using weighting factors obtained from the regression analysis of subjective evaluations. Based on the proposed method, drivability for heavy duty vehicles was evaluated quantitatively under various operation conditions. The results of this evaluation were similar to those of subjective evaluation.
자유 음장 조건에서 빔형성 방법을 이용한 수직 및 경사입사 음향 임피던스의 측정
신창우(Chang Woo Shin),선종천(Jong Choen Sun),강연준(Yeon June Kang),백순권(Soon Kwon Paik) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The improved Beamforming method is proposed to measure the acoustic impedance and absorption coefficient in a free field. It is possible to estimate the acoustic impedance by separating incident and reflected signals with the Adaptive Nulling Method. The wavelet shrinkage method is applied to reduce the White Gaussian noise. Transfer function vector is used for obtaining better results instead of pressure vector. The proposed method was verified by the comparison of measurement and theoretical method. The results show that the proposed method is efficient to measure acoustic impedance for frequencies higher than 400 ㎐.