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        • KCI등재

          Noisy 한 CFD 결과에 대한 구속조건을 고려한 EGO 방법 연구

          배효길(H.G. Bae),권장혁(J.H. Kwon) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.4

          Efficient Global Optimization (EGO) method is a global optimization technique which can select the next sample point automatically by infill sampling criteria (ISC) and search for the global minimum with less samples than what the conventional global optimization method needs. ISC function consists of the predictor and mean square error (MSE) provided from the kriging model which is a stochastic metamodel. Also the constrained EGO method can minimize the objective function dealing with the constraints under EGO concept. In this study the constrained EGO method applied to the RAE2822 airfoil shape design formulated with the constraint. But the noisy CFD data caused the kriging model to fail to depict the true function. The distorted kriging model would make the EGO deviate from the correct search. This distortion of kriging model can be handled with the interpolation(p=free) kriging model. With the interpolation(p=free) kriging model, however, the search of EGO solution was stalled in the narrow feasible region without the chance to update the objective and constraint functions. Then the accuracy of EGO solution was not good enough. So the three-step search method was proposed to obtain the accurate global minimum as well as prevent from the distortion of kriging model for the noisy constrained CFD problem.

        • Noisy 한 CFD 결과에 대한 구속조건을 고려한 EGO 최적설계

          배효길(H.G. Bae),권장혁(J.H. Kwon) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

          Efficient Global Optimization (EGO) method is a global optimization technique which can select the next sample point systematically by infill sampling criteria (ISC) and search for the global minimum with less samples than the conventional global optimization. ISC function consists of the predictor and mean square error (MSE) provided from the kriging model which is a stochastic metamodel. Also the constrained EGO method can minimize the objective function dealing with the constraints under EGO concept. In this study the constrained EGO method-applied to the RAE2822 airfoil shape design formulated with the constraint. Even though the optimum shape was obtained efficiently by EGO method, the noisy CFD data caused the kriging model to fail to depict the true function. This study showed that the noisy CFD data could be managed to keep from distorting the true function by changing the correlation function or using the re-interpolation kriging model while retaining the property of global convergence.

        • 근사모델을 이용한 RAE2822 운용 불확실성 강건최적설계

          배효길(H.G. Bae),권장혁(J.H. Kwon) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5

          In the view of robust design optimization, RAE2822 airfoil was designed to achieve not only the maximum lift-to-drag ratio but also insensitivity of that. While the RAE2822 is flying at the cruise speed, Mach variation is considered as the operational uncertainty. In order to explore the design space, metamodels were introduced instead of consecutively computing the gradient. Also a metamodel was used to represent the sigma space. Using the metamodel, an optimum value was searched in the view of global optimization.

        • KCI등재

          공력해석과 RCS해석 통합 500 lbs급 공대지 미사일 최적설계

          배효길(Hyogil Bae),이광기(Kwangki Lee),정준오(Juno Jeong),상대규(Daekyu Sang),권장혁(Jang Hyuk Kwon) 한국항공우주학회 2012 韓國航空宇宙學會誌 Vol.40 No.2

          최적설계 프레임워크를 구성하여 미사일 개념설계 단계에 필요한 공력해석(DATCOM)과 RCS 해석(POFACETS) 프로세스를 통합하였다. 미사일 형상정의는 제작과 설계의 동시성과 형상정보 산출 등을 목적으로 CAD(CATIA)를 기반으로 하였다. 정의된 형상정보가 자동적으로 해석 프로세스에 입력되도록 ModelCenter를 이용하여 프로세스들을 연결 하였다. 군요구도 정립부터 요구도 평가를 거쳐 미사일 설계 기준형상을 선정하였고, 양항비를 망대 구속조건으로 하여 RCS 최소화 최적설계를 실시하였다. 본 논문에서 구성한 최적설계 프레임워크를 이용하여 미사일 개념설계 단계에서 여러 미사일 형상들에 대한 효율적인 분석과 다양한 설계 전략을 구현할 수 있음을 확인하였다. Aerodynamic analysis(DATCOM) and radar cross section(RCS) analysis(POFACETS) were integrated for the air-to-surface missile concept design using a design framework. The missile geometry was defined based on the CAD(CATIA) for synchronizing the manufacturing with design processes. Aero/RCS analyses were linked with the CAD process under the ModelCenter framework in order to receive the geometry data automatically. The missile design baseline configuration was selected from ROC(requirement of capability). Then the RCS minimization was performed subject to thelargerthebetter constraint of the missile lift-to-drag ratio. This study demonstrated that various design strategies can be performed efficiently about many missile configurations using this design framework in the missile conceptual design phase.

        • 세계 민간 항공기 시장 현황과 전망

          배효길(Bae, Hyo-gil),강왕구(Kang, Wang-gu),이해창(Lee, Hae-chang) 한국항공우주연구원 2014 항공우주산업기술동향 Vol.12 No.1

          세계적인 여러 악재에도 불구하고 항공수요는 거의 매년 증가세를 유지해 오고 있다. 최근 세계 경기 회복세에 힘입어 Boeing 과 Airbus의 수주잔량도 10,639대로 역대 최고치를 보이고 있다. 또한 신흥발전국의 GDP 성장과 더불어 여행 빈도수의 증가에 따라 중국과 인도를 중심으로 아시아의 저가항공사(LCC)의 성장이 증가되고 있다. 이에 따라 대형 항공기뿐만 아니라 중형 항공기 시장도 점점 확대되고 있다. 향후 20년간 대형 항공기의 인도대수는 약 3만대 이상 될 전망이고, 중형 항공기는 12,800대가 인도될 전망이다. 하지만 항공시장의 감소주기 도래와 공급과잉, 유가상승과 같은 요인들로 항공 산업의 전망에 불확실성을 가져 올 수 있다. Despite of the several global disasters, the market demand has been maintaining the increase almost every year. Recently the global economic recovery causes the backlog of Boeing and Airbus to be at all time high as 10639 units. In addition of GDP(gross domestic product) growth in the emerging market, LCCs(low cost carrier) in the asia region continue to prosper according to the increment of trip per capita by leading from China and India. Therefore the regional aircrafts as well as jetliners also expand its market. For twenty years from now the delivery of jetliner will amount to over 30,000 units and the delivery of regionals reach at 12,800 units. However, the advent of decline cycle of aircraft market, the surplus of delivery surplus and the rise of oil price could be the uncertainties for aircraft market outlook.

        • 근사모델을 이용한 날개 평면형상 공력형상설계 방법

          배효길,정소라,Bae, Hyogil,Jeong, Sora 항공우주시스템공학회 2014 항공우주시스템공학회지 Vol.8 No.4

          '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

          In preliminary design phase, the wing geometry of the civil aircraft was determined using the empirical equation and historical data. To make wing geometry more aerodynamically efficient, an aerodynamic shape optimization was conducted. For this purpose the parametric modeling, high fidelity CFD analysis and metamodel-based optimal design technique were adopted. The parametric modeling got the design process to achieve the improvement by generating the configuration outputs easily for the major design variables. The optimal design equations were formularized as the type of the multi-objective functions considering low/high speed and lift/drag coefficient. The optimal solution was explored with the help of the kriging metamodel and the desirability function, therefore the optimal wing planform was sought to be excellent at both low and high speed region. Additionally the optimal wing planform was validated that it was excellent not only at the specific AOA, but also all over the range of AOA.

        • 95인승급 터보프롭 중형항공기 꼬리날개 사이징

          이장호,강영신,배효길,이해창,Lee, Jangho,Kang, Youngsin,Bae, Hyogil,Lee, Hae-Chang 항공우주시스템공학회 2013 항공우주시스템공학회지 Vol.7 No.3

          '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

          Tail wing is important to designing of civil aircrafts, because it is responsible for aircraft stability and control. Tail wing has a role in aircraft control and makes aircraft fly stably without any pilot control input. Also, designing of tail wing determine trim drag force in whole aircraft. Center of gravity(CG) of aircraft travels with various effects as placement of passenger's seats, location of cargo bay, etc. In designing horizontal tail volume, aircraft CG travel has to be considered to have margin so that it should be sized to provide adequate stability and control for the airplane's entire CG range throughout the flight envelope. Finally, it is essential to have sufficient elevator control to perform stall at forward CG for all flaps down configurations. Such stalls establish the FAR stall speed which airplane take-off and landing performance. This paper deals with the process for tail wing design regarding the aircraft CG travel and results for 95-seat type turboprop aircraft.

        • KCI등재

          학령기 아동의 어머니와 교사에 대한 애착과 사회적 유능감의 관계

          이희영(Lee Hee-Yeong),배효심(Bae Hyo-Sim) 한국열린교육학회 2007 열린교육연구 Vol.15 No.2

          '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

          본 연구는 학령기 아동의 어머니와 교사에 대한 애착과 사회적 유능감의 관계를 알아보고자 수행되었다. 초등학교 5, 6학년생 432명을 대상으로 어머니와 교사에 대한 애착 및 사회적 유능감 검사를 실시하였으며, 수집된 자료는 다변량 분산분석을 사용하여 분석하였다. 연구에서 나타난 주요 결과는 다음과 같다: 첫째, 어머니와 교사에 대한 애착 수준에 따라 아동의 사회적 유능감의 정도는 모든 하위 영역에서 유의미한 차이가 있었다. 즉, 어머니와 교사에 대한 애착 수준이 높은 집단이 낮은 집단에 비하여 사회적 유능감 점수가 유의미하게 높았다. 둘째, 어머니에 대한 애착 수준과(2)x교사에 대한 애착 수준(2)에 따른 4가지 복합애착유형 집단에 따라 사회적 유능감은 유의미한 차이가 있었다. 특히 어머니나 교사 중 어느 한 사람 또는 두 사람 모두에게 높은 애착을 형성한 아동은 두 사람 모두에게 낮은 애착을 형성한 아동보다 높은 수준의 사회적 유능감을 보였다. 이러한 결과가 교사에게 주는 시사점을 논의하였고, 본 연구의 제한점과 함께 후속 연구를 위한 제언을 하였다. This study was conducted to investigate the relationship of attachment to mother and teacher to the social competence of elementary school children. Subjects were three-hundred seventy-one 5th and 6th graders. Participants completed two subscales(mother and teacher) of the Inventory of Parent and Peer Attachment - Revised for Children and Social Competence Scale. Collected data were analyzed using MANOVA. Research findings of this study can be summarized as follows: First, there were statistically significant differences in all the sub-factors(namely, sociability, interpersonal adjustment, social participation, initiative and popularity) of social competence according to attachment to teacher. Second, there were statistically significant differences in social competence according to four multiple attachment type which is classified by the level of attachment to mother and teacher. More specifically, children who are more attached to both mother and(or) teacher showed higher social competence than those who are less attached to both mother and teacher. It was concluded that although attachment to mother is a little more important, attachment to teacher is also important in developing social competence of elementary school children. The implications of this study for teacher were discussed and recommendations for future research based upon the limitations of this study were made.

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