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노주현(Joohyun RHO),곽민호(Minho Kwak),강형민(Hyungmin KANG),정지훈(Jihoon JEONG),정신규(Shinkyu JEONG),이동호(Dongho LEE) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
A robust design of panhead shape of pantograph is performed by using CFD analysis, Kriging model and genetic algorithm. In this paper, for the optimal performance and the robustness of the panhead shape, the drag coefficient and the change of lift coefficient about the angle of attack are minimized, respectively. In order to reduce the computing time and to ensure the global search of optimal point, Kriging-based genetic algorithm is used. Throughout this research, the optimized elliptic airfoil is robust to the uncertainty of wind condition and a fluctuating lift force is restricted. It also helps to reduce abrasion of catenaries and aero acoustic noises.
돌풍 장치를 적용한 고속철도 선로 유동에 대한 실험 연구
노주현(Joohyun Rho),김종용(Jongyong Kim),구요천(Yocheon Ku),윤수환(Suhwan Yun),권혁빈(Hyukbin Kwon),조동현(Donghyun Cho),이동호(Dongho Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
A series of wind tunnel testing have been performed to investigate the flow filed in the vicinity of the track induced by high-speed train. To simulate the unsteady wind gust by train, large scale subsonic wind tunnel of Korea Air Force Academy and wind gust generator with damper control system and grid array have been employed. To verify the simulation of wind gust, unsteady wind velocity history have been measured by pitot tube and 25 port rake static tube and the wind tunnel results been compared with the measurements on the Seoul-Busan high-speed line. For further examination of the flow-filed, hot-wire anemometry has also been used. From these results, the ballast-flying phenomenon was found in the simulated unsteady flow and the conditions which increase a possibility of the ballast-flying was investigated.
인공 신경망 기법을 이용한 리어 스포일러의 강건 최적 설계
노주현(Rho Joohyun),윤수환(Yun Su-Hwan),전상욱(Jun Sangook),전용희(Jeon Yong-Hee),이동호(Lee Dong-Ho) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
To improve the stability and aerodynamic performance of a car, robust design optimization of the rear spoiler was implemented in this study. At first, sensitivity analysis for controllable and uncontrollable factors was carried out with Taguchi method. Through it, effect of factors on the stability and performance of the car was investigated. Finally, robust design of the rear spoiler was achieved with Monte Carlo Simulation and artificial neural network. As a result of this research, we could confirm the optimum that uncontrollable factors have less influence on the performance, which agrees to the result of sensitivity analysis. Furthermore, the stability and performance of a car is improved through this work.
자동차 형상함수와 3차원 프린터를 이용한 신속 프로토 형상제작
노주현(Joohyun Rho),정신규(Sinkyu Jeng),곽민호(Minho Kwak),이동호(Dongho Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Owing to the present higher oil price and the Climatic Change Convention, the fuel efficiency, the environmental performance and the eco style affect vehicle development process and consumers' choices more and more. The efficiency of development is important especially in initial design state. The objective of this research is an introduction of design/manufacturing process of a prototype in a conceptual design using the Vehicle Modeling Function and a 3-dimensional printer. First, the Vehicle Modeling Function was introduced. With 3-dimensional Printer, the fast prototype realization of the aerodynamically designed model in the functional type was explained. Also the fast prototype manufacturing can be applied to the 3-dimensional automobile shape optimization design process.
MCS를 이용한 자동차 공력 성능의 신뢰성 설계에 대한 연구
구요천(Yocheon Ku),노주현(Joohyun Rho),윤수환(Suhwan Yun),김태윤(Taeyoon Kim),이동호(Dongho Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The objective of this study is the provision of the method to find the reliable ranges of the design variables where the required performances are satisfied. The reliability-based design optimization was performed to find the reliable ranges and the Monte Carlo Simulation was used to evaluate the probability of success. And the empirical model was adopted for the efficient prediction of the aerodynamic performances of an automobile. Through this study, the reliable ranges of the design variables with 2-sigma or 3-sigma could be found and there sizes were maximized for the design flexibility. The provided method is expected to improve the efficiency of the development process of a new automobile by reducing the iterations between the automobile external shape design and evaluation of the aerodynamic performances.
문성목(Seongmok Moon),노주현(Joohyun Rho),이경훈(Kyounghoon Lee) 한국자동차공학회 2017 한국자동차공학회 학술대회 및 전시회 Vol.2017 No.11
In this study, a 3-dimensional transient computational study is carried out to estimate the effect of pressure wave for high speed trains that are crossing in open air or tunnel at 350km/h speed. The dynamic mesh technique is applied to simulate the reciprocal motion of high speed trains, and the initial condition using a smooth starting method is adopted to eliminate a numerical pressure wave that may initially take place by the impulsive start. Pressure waves give rise to large pressure transients that a positive-negative pulse pressure is generated as the train head passes another train, which a negative-positive pulse as the train tail passes. Pressure wave characteristics for the crossing of high speed trains are represented through the numerical analysis, which predicts resultant aerodynamic forces by pressure transient acting on the trains.
실제 풍황 조건에 따른 풍력발전기의 민감도 분석방법 연구
윤광용(Yoon, Kwangyong),노주현(Rho, Joohyun),김현철(Kim, Hyunchul),이권희(Lee, Kwonhee) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
설계단계의 풍력발전시스템 하중계산은 20년이 넘는 시스템 수명과 효율을 결정하는 중요한 부분이다. 일반적인 규정서 기반의 설계하중 계산은 실제 풍황 조건인 발전기 상호 간섭, 설치 지형의 특성 등을 상세히 묘사하기 어렵다. 풍력발전기 설계 단계에서 검토된 평균풍속 또는 난류강도 등이 규정(IEC, GL 등)을 만족한다 하더라도 설계값과 실제값은 서로 다른 결과를 나타낼 수 있다. 본 연구에서는 기 설계된 풍력발전기가 최적 효율을 낼 수 있는 풍력단지의 풍황 특성(평균풍속과 난류강도 등)의 범위를 보다 정확하게 제시하여 설치되는 풍력발전기의 수명과 효율을 높이는 방법을 연구하였다. 이를 위하여 당사의 2MW급 IEC Class II-A로 설계된 직접 구동형 풍력발전기에 대해, 다양한 평균 풍속(7m/s~10m/s)과 난류강도(14%~20%)를 고려한 하중 계산을 수행하였다. 하중 분석을 통해 실제 풍황 조건에 따른 극한하중 산출 및 피로수명의 민감도를 검토하여 풍력발전기 운용의 풍속과 난류강도의 최적범위 제시하여 발전단지 설계에 활용할 수 있도록 하였다.
차세대 고속열차(HEMU-400X)의 팬터그래프 시스템에 대한 공력특성 연구
이영빈(Yeongbin Lee),노주현(Joohyun Rho),곽민호(Minho Kwak),이재호(Jaeho Lee),김규홍(Kyu Hong Kim),이동호(Dong-Ho Lee) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7
This paper describes on aerodynamic characteristics of pantograph system for Next generation high speed train(HEMU-400). The pantograph which supports electric power is located on the roof. Because of this, it generate high drag, severe acoustic noise and vibration which induced unstable flow due to complex configuration. Therefore, the design of high efficient pantograph needs to increase operational speed. In this research, wind tunnel tests were performed to design a high efficient pantograph system using 1/4 scaled model which were KTX-II pantograph, single arm pantograph and periscope type pantograph with square cylinder shape panhead and optimized shape panhead. For real operational condition, flow directions were adapted by rotation of pantograph. From this results of wind tunnel, it is checked that the pantograph with optimized panhead and single arm type or periscope type has better aerodynamic performance. In addition, lift control device and spoiler in pantograph were tested to investigate the validity of application.
Wind tunnel test for the 20% scaled down NREL wind turbine blade
조태환(Cho, Taehwan),김철완(Kim, Cheolwan),김양원(Kim, Yangwon),노주현(Rho, Joohyun) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.11
The 'NREL Phase VI' model with a 10.06m diameter was tested in the NASA Ames tunnel to make a reference data of the computational models. The test was conducted at the one rotational speed, blade tip speed 38m/s and the Reynolds number of the sectional airfoils in that test was around 1E6. The 1/5 scale down model of the 'NREL Phase VI' model was used in this paper to study the power characteristics in low Reynolds number region, 0.1E6 ~ 0.4E6 which is achievable range for the conventional wind tunnel facilities. The torque generated by the blade was directly measured by using the torque sensor installed in the rotating axis for a given wind speed and rotational speed. The power characteristics below the stall condition, lambda > 4, was presented in this paper. The power coefficient is very low in the condition below the Re. 0.2E6 and rapidly increases as the Re. increases. And it still increases but the variation is not so big in the condition above the Re. 0.3E6. This results shows that to study the performance of the wind turbine blade by using the scaled down model, the Re. should be larger than the 0.3E6.