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권오성(Ohsung Kwon),김병훈(Byunghun Kim),길경섭(Gyoungsub Kil),고영성(Youngsung Ko) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.11
추진제탱크 내의 극저온 추진제는 발사체의 비행 과정동안 주변으로부터 에너지를 흡수하여 온도가 상승한다. 비행 종료 시점에 있어 터보펌프 입구 요구조건 이상으로 온도가 상승된 추진제는 사용할 수 없는 잔류추진제로 남게 된다. 본 논문에서는 극저온 추진제 상층부의 온도변화를 살펴보기 위하여 추진제 표면 근처에서의 열전달계수를 구해보고자 하였다. 추진제 상층부의 열전달을 전도로 단순화하여 열전달계수를 예측하는 방법을 제시하였다. 이를 통해 얻어진 추진제 상층부의 온도를 시험데이터와 비교하여 열전달계수 예측 방법의 적용 가능성을 확인하였다. The temperature of cryogenic propellant in the propellant tank increases during flight due to heat input from surroundings. The propellant which temperature rises up over the required condition of turbo-pump remains as unusable propellant at the end of flight. In this paper the estimation method of the heat transfer coefficient at the upper layer of cryogenic propellant was presented. The heat transfer mode at the propellant upper layer was considered as conduction. Temperature distributions near propellant surface obtained from heat transfer coefficient were compared with test data to show the possibility of this method.
비행시험 데이터를 통한 추진제탱크 가압가스 요구량 예측 프로그램 검증
권오성(Ohsung Kwon),한상엽(Sangyeop Han),조인현(Inhyun Cho),고영성(Youngsung Ko) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11
추진제탱크의 가압에 소요되는 가압가스 요구량을 예측하기 위해 개발된 프로그램을 비행시험 데이터를 통해 검증하였다. 개발된 예측 프로그램은 이미 지상에서의 시험데이터를 통해 검증되었으나, 프로그램의 신뢰성을 높이기 위하여 2002년 발사된 3단형과학로켓(KSR-III)의 비행시험 데이터와 비교하였다. 비행시험에서는 추진제탱크로 유입되는 가압가스의 온도를 측정하지 않았으므로 데이터 분석을 통하여 적절한 온도를 가정하였다. 수치해석 프로그램과 비행시험 데이터 비교 결과 가압가스 요구량에 있어 약 6%의 오차를 보여줌으로써 예측 프로그램의 유효성을 입증하였다. Calculation program to predict required pressurant mass for propellant tank was verified through flight test data. This program was already developed and verified through ground test data, but to increase reliability of program, it was compared with flight test data of KSR-III launched in 2002. Because pressurant temperature incoming to propellant tank was not measured in flight test, that was assumed in calculation program. Required pressurant mass and inside temperature of oxygen tank dome was compared. Validation of calculation program was verified by showing required pressurant mass accuracy of 6%.
권오성(Ohsung Kwon),김병훈(Byunghun Kim),길경섭(Gyoungsub Kil),고영성(Youngsung Ko) 한국추진공학회 2012 한국추진공학회지 Vol.16 No.3
The temperature of cryogenic propellant in the propellant tank increases during flight due to heat input from surroundings. The propellant which temperature rises up over the required condition of turbo-pump remains as unusable propellant at the end of flight. In this paper the estimation method of the heat transfer coefficient at the upper layer of cryogenic propellant was presented. The heat transfer mode at the propellant upper layer was considered as conduction. Temperature distributions near propellant surface obtained from heat transfer coefficient were compared with test data to show the possibility of this method.
도심지 기반의 자율주행을 위한 가속도 프로파일이 적용된 퍼지 제어 시스템
권오성(Ohsung kwon),윤정일(Jungil Yoon),김정하(Jungha Kim) 한국자동차공학회 2017 한국자동차공학회 부문종합 학술대회 Vol.2017 No.5
In this paper, we propose a longitudinal acceleration controller invoked fuzzy logic to follow acceleration plans considering autonomous urban driving. To solve the difficult problem which is formulating the powertrain model of vehicle, therefore we applied fuzzy logic to the controller. The controller receives the acceleration error, jerk and APS(Accel position sensor) signal, and outputs displacement of APS signal and brake pedal position to control the speed of vehicle. In addition, we estimate the gradient with IMU(Inertial measurement unit) in order to maintain the desired speed even on the slope, and complement the performance of the controller by selecting suitable APS signal and brake pedal control for the situation.
권오성(Ohsung Kwon),조남경(Namkyung Cho),정용갑(Yonggahp Chung),한상엽(Sangyeop Han),김영목(Youngmog Kim) 한국추진공학회 2007 한국추진공학회지 Vol.11 No.2
The performance test of recirculation line in propellant feeding system was carried out. Liquid oxygen was used as cryogenic propellant and helium was used as recirculation promotion gas. Tests were done in cases at atmospheric pressure and at pressure of 4 barg in the ullage space of propellant tank. Liquid oxygen recirculation flowrate with helium injection flowrate and temperature distribution along the line were measured. There was appropriate helium injection flowrate for gas-lift recirculation system. Test data were used to make calculation program by test data correlation method. In this paper the procedure of calculation was presented and the results were compared to test data.
적합도 공유 기법을 적용한 향상된 FastSLAM 알고리즘
권오성(Ohsung Kwon),현병용(Byeongyong Hyeon),서기성(Kisung Seo) 한국지능시스템학회 2012 한국지능시스템학회논문지 Vol.22 No.4
SLAM(Simultaneous Localization And Mapping)은 주변 환경에 대한 지도 작성과 자신의 위치를 인식하는 기법으로 주행 로봇 분야에서 널리 사용되고 있다. FastSLAM(A Factored Solution to the SLAM) 은 파티클 필터와 확장형 칼만 필터를 기반으로 한 대표적인 SLAM 기법중의 하나이나, 재추출 단계에서 입자들의 다양성이 상실되는 문제가 제기되고 있다. 본 논문에서는 적합도 공유기법을 사용하여 입자들의 다양성 상실에 관한 문제를 보완하는 방법을 제시하고, 기존의 기법들과 성능을 비교 및 분석한다. SLAM(Simultaneous Localization And Mapping) is a technique used by robots and autonomous vehicles to build up a map within an unknown environment and estimate a place of robot. FastSLAM(A Factored Solution to the SLAM) is one of representative method of SLAM, which is based on particle filter and extended Kalman filter. However it is suffered from loss of particle diversity. In this paper, new approach using fitness sharing is proposed to supplement loss of particle diversity, compared and analyzed with existing methods.
소재·부품 중소기업의 R&D 투자가 기업의 수익성에 미치는 영향에 대한 연구
Ohsung Kwon(권오성),Namin Park(박나민),Minsu Kim(김민수) 한국경영학회 2020 經營學硏究 Vol.49 No.5
As protectionism in each country has been widespread and export restrictions of Japan on materials have arisen, the voices of fostering the upstream sectors in Korea are rising. In particular, the materials and components industry plays an important role in the domestic manufacturing industry. In addition, domestic small and medium-sized enterprises (SMEs) occupy a large part in terms of absolute number of companies and employment ratio. Therefore, the analysis of SMEs in the materials and components industry can foster development of the upstream sectors in Korea. In particular, this study examines the effect of R&D investment by SMEs in the materials and components industry on profitability of the firms. In the case of the products in upstream sectors, the effect of R&D innovation is relatively slow because it takes a long time to reach the consumer. Based on the empirical data of SMEs in the materials and components industry, the proportion of R&D investment in that same year has negatively affected profitability of the firm. On the other hand, R&D investment in the next year was analyzed to have a positive effect on profitability. It suggests that, in the short term, R&D investment can damage profitability of the firm, whereas it can be beneficial in the long-run. This study is expected to understand profitable opportunity in terms of the R&D investment for SMEs and related authority in the materials and components industry.