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인공위성 구조모듈의 열변형 해석을 위한 온도 자동 변환 전산프로그램 개발
김도형(Do Hyung Kim),임형은(Hyung Eun Im),이희남(Huinam Rhee),황도순(Do Soon Hwang) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.11
지구궤도 상에서 운용되는 인공위성의 구조체는 태양의 영향으로 각 부품들 위치마다 온도 분포가 다르고 이에 따라 열변형을 하게 되며, 따라서 카메라 및 여러 과학 탑재체에 열지향 오차가 발생하게 된다. 이러한 열지향 오차를 줄이기 위해 위성 구조 설계 단계에서 인공위성 열 변형 해석을 필수적으로 하는데, 상대적으로 덜 상세한 위성 열 해석 모델을 이용하여 구한 3차원 구조체의 온도 분포 데이터를 이용하여 상세한 위성 구조해석 모델에 적합한 온도 분포 입력 데이터로 변화하는 과정이 필요하며, 이것은 매우 복잡하고 어려운 과정이어서 오류를 유발하기 쉽다. 본 연구에서는 내삽 및 외삽법을 이용하여 체계적이고 정확하게 온도 분포 데이터를 자동 변환하여 주는 알고리즘을 개발하였고 이를 기반으로 윈도우 그래픽 기반의 전산프로그램을 개발하였다. 본 연구에서 개발한 방법을 이용하면 다양한 위성구조체의 열변형 해석 시간을 획기적으로 단축시키고 정확성을 대폭 높일 수 있는 장점이 있다. Artificial satellite structures undergo thermal deformation during operation in Earth orbit depending on the temperature distribution. The thermal deformation directly causes thermal pointing errors of cameras and other scientific payloads. Therefore, it is necessary to perform the thermal deformation analysis of satellite structures to minimize thermal pointing errors. Because the thermal model and structural models have different structures, the temperature data generated using the thermal model is not compatible with the structural model. Therefore, there is a need for a temperature-conversion process between two models. In this paper, an effective algorithm is proposed for the automatic conversion process. Finally, a computer program is successfully developed to perform the precise conversion in a relatively short time period.
유전자알고리즘을 이용한 궤도차량 동력장치의 주행부하주기 도출
오철성(Chul-Sung Oh),임형은(Hyung-Eun Im),황원걸(Won-Gul Hwang) 한국자동차공학회 2005 한국 자동차공학회논문집 Vol.13 No.3
The durability of a vehicle is a very important performance which can be evaluated from endurance test. This study developed a procedure for determination of a duty cycle theoretically. Vehicle load data is classified and rearranged using standard test road profile. A load pattern and a duty cycles are extracted from classified vehicle data using genetic algorithm. A duty cycle could be utilized in dynamo test to meet required test mileage. The derived duty cycles have been verified by fatigue test through the dynamometer test.
[진동·소음부문] 2마이크로폰 인텐시티 프로브를 이용한 실내음장제어
김우영(Kim Woo-Young),임형은(Im Hyung-Eun),황원걸(Hwang Won-Gul) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This research altempts to find the useful active control strategies, which consider acoustic power as their control objective function for lightly damped enclosed sound field like a vehicle compa.1ment. An adaptive filtering algorithm for sound power control is suggested to implement for real time control of lightly damped enclosed sound field using least mean product adaptation strategy. To measure the sound intensity and sound power, we implemented 2 microphone probes and analyzed their characteristic and performance.<br/> To verify the method sound power based active noise control we performed to enclosed rectangular box with light damping wall. Experiments performed to compare noise reduction performance according to distance between noise source and probe. According to the results of experiment it is found that noise reduction performance isn't dependent on only acoustic coupling and modal coupling due to position of sound sources but also distance between actuator and probe
이은영(Eunyoung Lee),주승원(Seungwon Ju),성원석(Wonsuk Sung),양성대(Sungdae Yang),임형은(Hyung-Eun Im),황원걸(Won-Gul Hwang) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_2
A fixed-base vehicle simulator is developed. It consists of a real-time vehicle simulation system, a visual and audio system, and an experiment console. The system is designed and constructed with modular structure so that it can be easily extended and updated if necessary. It has three modes to work: real time driving simulation, traffic simulation, and ride quality simulation. It is expected that the proposed low-cost vehicle simulator can be used for the feasibility study of new control algorithms, driver's steering behavior research and ride quality studies.
황원걸(Won Gul Hwang),김우영(Woo Young Kim),임형은(Hyung Eun Im) 한국자동차공학회 1999 한국 자동차공학회논문집 Vol.7 No.3
ABSTRACT<br/> When developing a large bus, damper curves are primarily tuned to improve the ride and handling characteristics through the subjective feeling test. In order to save time and efforts, the optimization method is used to obtain the optimum characteristics of the dampers and springs which can improve ride and handling performance. We made a full vehicle model which consists of a body, rigid axles in the front and rear, air springs, dampers, tires, and steering system. An airspring and a damper are modeled including the nonlinear characteristics. <br/> We performed the damping and airspring curve optimization. The objective function for handling performance is RMS(Root Mean Squares) of the roll angle, roll rate, yaw rate, and lateral acceleration at the center of gravity of a body during a double lane change. And the objective function for ride comfort is WRMS(Weighted RMS) of the power spectral density of the vertical acceleration at the driver's seat, middle seat and rear seat. Design variables are the damping characteristic curves expressed by damping coefficient and damping exponent and air spring characteristic curves calculated by curve fitted experimental data.<br/> Since ride and handling performance have opposite characteristics, validity of optimum design system for suspension was examined by comparing changes for handling performance indices according to weighting factors.<br/>
안기원(Ki-Won Ahn),최기섭(Gi-Seob Choi),임형은(Hyung-Eun Im),황원걸(Won-Gul Hwang) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.11_1
The strength analysis for the trunnion shaft of dump truck is carried out with dynamic model and FEM model. Reaction forces of the trunnion shaft are calculated with DADS for the case of straight line driving and severe lane change manoeuvre. The calculated reaction forces are used to analyze the stresses of the trunnion shaft using MSC/NASTRAN. The safety design criterion is suggested to the important part such as trunnion shaft.<br/> <br/>
안기원(Ki Won Ahn),김우영(Woo Young Kim),임형은(Hyung Eun Im),황원걸(Won Gul Hwang) 한국자동차공학회 1999 한국 자동차공학회논문집 Vol.7 No.2
Ride comfort is one of the most important performance indices which decide the quality of a vehicle. If we can predict the performance of ride comfort by using computer simulations, the time and effort needed to improve ride comfort can be saved. A full vehicle model for a large bus with air suspension was developed, including nonlinearities of hydraulic damper and air suspension. Simulations were performed with this model to predict the ride comfort by using the 7DOF full car model. To evaluate ride comfort in vehicle dynamics, it is essential to describe a road surface profile precisely. We used a spatial domain power spectral density function method to generate road surface profiles.<br/> Field tests were performed using both bump road and real road conditions. RMS(Root Mean Square) values for a bump road and WRMS(Weighted RMS) of PSD(Power Spectral Density) and RSS(Root Sum of Squares) for random road were calculated and compared with the results of feeling tests. These comparisons showed that RSS gave good agreement with the results of feeling test, and can be used to evaluate the ride comfort for a vehicle.<br/>