다단 최적 설계 프레임워크를 활용한 전기추진 항공기 프로펠러 공력 최적 설계

권형일(Hyung-Il Kwon),이슬기(Seul-Gi Yi),최성임(Seongim Choi),김근배(Keunbae Kim) 한국항공우주학회 2013 韓國航空宇宙學會誌 Vol.41 No.3

본 연구에서는 프로펠러나 헬리콥터 로터와 같은 회전체의 공력 최적 설계를 위한 다단 최적 설계 프레임워크를 제안한다. 이 프레임워크는 플랜폼 설계와 단면의 형상 설계를 반복적으로 수행하는 설계 전략을 통해 회전체의 공력 성능 향상을 목표로 한다. 플랜폼 설계의 단계에서는 유전 알고리즘과 2차원 CFD 데이터베이스 기반의 깃 요소 모멘텀 이론을 이용하여 빠른 시간에 회전체의 공력 특성을 평가하여 최적점을 탐색하였다. 플랜폼 설계 후 단면에 유입되는 유동 조건을 예측하여 단면 형상 최적 설계를 수행하였다. 설계 과정에서 보다 면밀하게 유동 특성이 분석될 수 있도록 2차원 N-S 해석자와 민감도 기반의 최적화 알고리즘을 통해 최적해를 탐색하였다. 단면 형상이 설계된 후에 는 최적의 유동 조건을 산출할 수 있도록 플랜폼 설계를 반복적으로 수행하였다. 본 프레임워크를 1㎾급 전기추진용 항공기 프로펠러 설계에 적용하여 그 유효성을 3차 원 N-S 해석과 풍동 실험을 통해 검증하였다. 설계 후, 풍동 실험 결과를 기준으로 약 5%의 프로펠러 효율 증가를 얻을 수 있었다. A multi-level design optimization framework for aerodynamic design of rotary wing such as propeller and helicopter rotor blades is presented in this study. Strategy of the proposed framework is to enhance aerodynamic performance by sequentially applying the planform and sectional design optimization. In the first level of a planform design, we used a genetic algorithm and blade element momentum theory (BEMT) based on two-dimensional aerodynamic database to find optimal planform variables. After an initial planform design, local flow conditions of blade sections are analyzed using high-fidelity CFD methods. During the next level, a sectional design optimization is conducted using two dimensional Navier-Stokes analysis and a gradient based optimization algorithm. When optimal airfoil shape is determined at the several spanwise locations, a planform design is performed again. Through this iterative design process, not only an optimal flow condition but also an optimal shape of an EAV propeller blade is obtained. To validate the optimized propeller-blade design, it is tested in wind-tunnel facility with different flow conditions. An efficiency, which is slightly less than the expected improvement of 7% predicted by our proposed design framework but is still satisfactory to enhance the aerodynamic performance of EAV system.

Aircraft derivative design optimization considering global sensitivity and uncertainty of analysis models

Park, Hyeong-Uk,Chung, Joon,Lee, Jae-Woo The Korean Society for Aeronautical and Space Scie 2016 International Journal of Aeronautical and Space Sc Vol.17 No.2

Aircraft manufacturing companies have to consider multiple derivatives to satisfy various market requirements. They modify or extend an existing aircraft to meet new market demands while keeping the development time and cost to a minimum. Many researchers have studied the derivative design process, but these research efforts consider baseline and derivative designs together, while using the whole set of design variables. Therefore, an efficient process that can reduce cost and time for aircraft derivative design is needed. In this research, a more efficient design process is proposed which obtains global changes from local changes in aircraft design in order to develop aircraft derivatives efficiently. Sensitivity analysis was introduced to remove unnecessary design variables that have a low impact on the objective function. This prevented wasting computational effort and time on low priority variables for design requirements and objectives. Additionally, uncertainty from the fidelity of analysis tools was considered in design optimization to increase the probability of optimization results. The Reliability Based Design Optimization (RBDO) and Possibility Based Design Optimization (PBDO) methods were proposed to handle the uncertainty in aircraft conceptual design optimization. In this paper, Collaborative Optimization (CO) based framework with RBDO and PBDO was implemented to consider uncertainty. The proposed method was applied for civil jet aircraft derivative design that increases cruise range and the number of passengers. The proposed process provided deterministic design optimization, RBDO, and PBDO results for given requirements.

Aircraft derivative design optimization considering global sensitivity and uncertainty of analysis models

박형욱,정준,이재우 한국항공우주학회 2016 International Journal of Aeronautical and Space Sc Vol.17 No.2

Aircraft manufacturing companies have to consider multiple derivatives to satisfy various market requirements. They modify or extend an existing aircraft to meet new market demands while keeping the development time and cost to a minimum. Many researchers have studied the derivative design process, but these research efforts consider baseline and derivative designs together, while using the whole set of design variables. Therefore, an efficient process that can reduce cost and time for aircraft derivative design is needed. In this research, a more efficient design process is proposed which obtains global changes from local changes in aircraft design in order to develop aircraft derivatives efficiently. Sensitivity analysis was introduced to remove unnecessary design variables that have a low impact on the objective function. This prevented wasting computational effort and time on low priority variables for design requirements and objectives. Additionally, uncertainty from the fidelity of analysis tools was considered in design optimization to increase the probability of optimization results. The Reliability Based Design Optimization (RBDO) and Possibility Based Design Optimization (PBDO) methods were proposed to handle the uncertainty in aircraft conceptual design optimization. In this paper, Collaborative Optimization (CO) based framework with RBDO and PBDO was implemented to consider uncertainty. The proposed method was applied for civil jet aircraft derivative design that increases cruise range and the number of passengers. The proposed process provided deterministic design optimization, RBDO, and PBDO results for given requirements.

Development of optimal water distribution system design and operation approach considering hydraulic and water quality criteria in many-objective optimization framework

Choi Young Hwan 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.2

Water distribution systems (WDSs) are major infrastructure, and it needs to consider economic, hydraulic stability, and water quality safety to optimal design and operation of WDSs. However, the previous studies related to WDS design and operation were focused on each field (i.e. design: optimal pipe diameter, pump sizing, and valve location; operation: optimal pump scheduling, etc.) even though the WDS design and operation have a correlation. Therefore, to achieve economic feasibility, hydraulic stability, and water quality safety under WDS design and operation process, this study develops an optimal WDS design and operation approach considering hydraulic and water quality criteria in the many-objective optimization framework. To consider design and operation, this study applies three objective functions to minimize the total design and operation cost (i.e. the pipe cost, pump construction, and pump operation cost), maximize system robustness, and minimize the amount of chlorine requisition simultaneously under the hydraulic and quality constraints. The proposed optimal WDS design and operation model was applied to the two-stage optimization procedures. The first process determined the optimal pipe diameter set. The second process determined the optimal pump construction and scheduling considering three objective functions such as the total pump cost, the system robustness, and the quantity of the required residual chlorine for determining optimally the available number of pumps, capacity, and scheduling. For the optimization, the self-adaptive multi-objective harmony search is used and a famous benchmark network for the optimal design and pump operation of WDSs is applied to verify the proposed approach. This study can provide a new perspective on WDS design and operation technique considering the essential design factors to the water utility.

Uncertainty-based MDO for aircraft conceptual design

Park, Hyeong-Uk,Lee, Jae-Woo,Chung, Joon,Behdinan, Kamran Emerald Group Publishing Limited 2015 Aircraft engineering and aerospace technology Vol.87 No.4

<P><B>Purpose</B></P> <P> – The purpose of this paper is to study the consideration of uncertainty from analysis modules for aircraft conceptual design by implementing uncertainty-based design optimization methods. Reliability-Based Design Optimization (RBDO), Possibility-Based Design Optimization (PBDO) and Robust Design Optimization (RDO) methods were developed to handle uncertainties of design optimization. The RBDO method is found suitable for uncertain parameters when sufficient information is available. On the other hand, the PBDO method is proposed when uncertain parameters have insufficient information. The RDO method can apply to both cases. The RBDO, PBDO and RDO methods were considered with the Multidisciplinary Design Optimization (MDO) method to generate conservative design results when low fidelity analysis tools are used. </P> <P><B>Design/methodology/approach</B></P> <P> – Methods combining MDO with RBDO, PBDO and RDO were developed and have been applied to a numerical analysis and an aircraft conceptual design. This research evaluates and compares the characteristics of each method in both cases. </P> <P><B>Findings</B></P> <P> – The RBDO result can be improved when the amount of data concerning uncertain parameters is increased. Conversely, increasing information regarding uncertain parameters does not improve the PBDO result. The PBDO provides a conservative result when less information about uncertain parameters is available. </P> <P><B>Research limitations/implications</B></P> <P> – The formulation of RDO is more complex than other methods. If the uncertainty information is increased in aircraft conceptual design case, the accuracy of RBDO will be enhanced. </P> <P><B>Practical implications</B></P> <P> – This research increases the probability of a feasible design when it considers the uncertainty. This result gives more practical optimization results on a conceptual design level for fabrication. </P> <P><B>Originality/value</B></P> <P> – It is RBDO, PBDO and RDO methods combined with MDO that satisfy the target probability when the uncertainties of low fidelity analysis models are considered.</P>

Possibility Based Small Aircraft Design Optimization Using Database Driven Uncertainty Approach

Hsu Myat Naing,Daniel Neufeld,Nguyen Nhu Van,Maxim Tyan,Jae-Woo Lee,Sangho Kim 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.4

Since deterministic optimization method without considering uncertainty lead to unreliable designs, it is required to consider design methods that take into account of the input uncertainty. In this study, uncertainties which are from the analysis methods that do not perfectly correspond to physical phenomenon are taken into account in optimization process. Possibility Base Design Optimization Design Optimization is one of the methods for accounting for uncertainties by modeling each source of uncertainty as a fuzzy number. Possibility Base Design Optimization with performance measure approach that improves numerical efficiency and stability is used in this design optimization. This paper describes a process that implements a design optimization using possibility theory to perform small aircraft conceptual design optimization in order to produce results that are more conservative but more trustworthy than conventional optimization approach.

Aircraft derivative design optimization considering global sensitivity and uncertainty of analysis models

Hyeong-Uk Park,Joon Chung,Jae-Woo Lee 한국항공우주학회 2016 International Journal of Aeronautical and Space Sc Vol.17 No.2

Aircraft manufacturing companies have to consider multiple derivatives to satisfy various market requirements. They modify or extend an existing aircraft to meet new market demands while keeping the development time and cost to a minimum. Many researchers have studied the derivative design process, but these research efforts consider baseline and derivative designs together, while using the whole set of design variables. Therefore, an efficient process that can reduce cost and time for aircraft derivative design is needed. In this research, a more efficient design process is proposed which obtains global changes from local changes in aircraft design in order to develop aircraft derivatives efficiently. Sensitivity analysis was introduced to remove unnecessary design variables that have a low impact on the objective function. This prevented wasting computational effort and time on low priority variables for design requirements and objectives. Additionally, uncertainty from the fidelity of analysis tools was considered in design optimization to increase the probability of optimization results. The Reliability Based Design Optimization (RBDO) and Possibility Based Design Optimization (PBDO) methods were proposed to handle the uncertainty in aircraft conceptual design optimization. In this paper, Collaborative Optimization (CO) based framework with RBDO and PBDO was implemented to consider uncertainty. The proposed method was applied for civil jet aircraft derivative design that increases cruise range and the number of passengers. The proposed process provided deterministic design optimization, RBDO, and PBDO results for given requirements.

다중목적 최적화 알고리즘을 활용한 주거복합커뮤니티공간 디자인 연구

김범승 ( Kim Beomseung ),이우형 ( Lee Woohyoung ) 한국공간디자인학회 2021 한국공간디자인학회논문집 Vol.16 No.8

(연구배경 및 목적) 최근 도심지내 낙후된 저층주거지를 활용한 중/고밀의 주거와 생활 SOC를 함께 제공하는 주거복합커뮤니티개발이 진행되고 있다. 건축적으로 이러한 도심에 위치한 복합 프로그램의 고밀 집적화는 환경적 성능 및 각 용도별 상이한 조건을 동시에 만족시킴이 필수적으로 요구된다. 이는 기존 블랙박스식 설계방법으로는 그 대응에 한계를 가짐으로 본 디자인은 그 대안으로 다중목적 최적화 알고리즘을 활용한 설계방법에 주목하여 부지내 자체 건축물을 포함한 인접 컨텍스트의 영향을 고려한 최적 일사량 기준과 용도별 상충되는 상이한 설계조건을 함께 만족시키는 최적건축구성이 반영된 주거복합커뮤니티공간에 대한 설계안을 제안한다. 이를 위해 특정 부지 상의 설계조건을 가진 예제를 설정하고, 다수의 조건을 동시에 연산하는 다중목적 유전알고리즘을 활용하여 도출된 배치 및 건물형태를 반영한 설계안을 도출한다. (연구방법) 예제로 서울시 정릉재개발구역내 경사지에 위치한 낙후된 저층주거지를 대상으로 지역의 문제점에 대응하는 주거, 상업, 커뮤니티 시설을 포함한 주거복합커뮤니티공간으로 설정한다. 인접 컨텍스트와 부지내 건축물군의 관계를 기반으로 일사량 기준 환경적 조건과 각 용도별 건축물에 요구되는 조망 및 인지성 조건을 동시에 만족시키는 배치와 형태를 중심으로 설계안을 도출한다. 이를 위해 파라메트릭 디자인 툴인 라이노 그라스하퍼(Rhino Grasshopper) 기반의 다중목적 최적화 에드온인 옥토퍼스(Octopus)를 활용한다. 옥토퍼스로 도출된 다수의 솔루션 군에 대한 성능적 및 계획적 관점의 검토를 통해 예제의 복합적 요구조건을 충족시키는 솔루션을 선정하여 디자인에 적용한다. (결과) 도출된 설계안은 가장 중심인 건축물의 배치와 형태뿐만 아닌 지역사회에 대한 다양한 요구사항과 문제점에 대응하는 도시적, 건축적 제안을 포함한다. 먼저 도시적 관점에서 인근지역과 단절된 지역사회의 물리적, 사회-경제적 문제점에 대응하기 위해 요구되는 시설과 기능을 제공함으로 지역사회의 사회 통합적 가치를 강화하였다. 건축적 관점에서 최적화 유전알고리즘으로 도출된 연산결과를 통해 지역시설을 포함한 복합개발의 환경적 성능을 포함한 다수의 복합적 요구조건을 충족시켰다. 추가적으로 기술적 관점에서 기존 건축설계과정에 내재된 주관적 자의성에 대한 한계를 넘어서는 객관성에 기초한 증거기준디자인을 도출하였다. (결론) 본 디자인은 설정된 예제에 대한 대안을 도출함을 통해 건축설계에 있어 새로운 디지털 툴과 연동된 최적화 유전알고리즘의 적용성과 잠재적 활용 가능성을 확인하였으며, 나아가 새로운 기술적 혁신이 접목되어 기존 전통적 건축설계방식이 가진 한계점을 극복하는 다중목적 최적화의 효용성을 확인하였다. 나아가 진보된 신기술과 건축설계와의 실용적 접목에 대한 범용성의 확대하는데 의미를 가진다. (Background and Purpose) Recently, a residential complex community development that provides medium/high-density housing and living SOC using the blighted low-rise residential area in the downtown area is being developed. Architecturally, the high-density integration of complex programs is essential to simultaneously satisfying different requirement for environmental performance and each use. As the existing black box design method has a limit to its response, this design focuses on the design method using a multi objective optimization algorithm and considers the impact of the adjacent context including the own building within the site. We propose a design for a residential complex community space that reflects the optimal architectural composition that satisfies the different design conditions that conflict with each other. (Method) For design example, it is set as a residential complex community space including residential, commercial, and community facilities that respond to community problems for blighted area located on a slope site in the Jeongneung Redevelopment Area in Seoul. Based on the relationship between the adjacent context and the group of buildings on the site, the design is drawn based on the site plan and shape that simultaneously satisfy the environmental optimization based on insolation and the view and perception requirements for each use. To do this, it utilizes Octopus, a multi objective optimization add-on based on Rhino Grasshopper. The optimal solution that meets the complex requirements of the example is selected and applied to the final design through the review of performance and planning for multiple solution groups derived from Octopus. (Results) The derived design includes not only site plan and shape of the most importantly, but also urban and architectural aspects that respond to various requirements for the community. First, from an urban point of view, the social integration of the community was strengthened by providing functions required to respond to the physical and socio-economic problems of the community cut off from the surrounding. From the architectural point of view, through the calculation results derived from the optimization, a number of complex conditions including the environmental performance of complex including local facilities were satisfied. In addition, from a technical point of view, evidence-based design based on objectivity that goes beyond the limits of subjective arbitrariness inherent in the existing architectural design process was applied. (Conclusions) This design confirmed the applicability and potential use of an optimization genetic algorithm linked with a new digital tool in architectural design by deriving alternatives to the set examples. The effectiveness of multi objective optimization to overcome the limitations of traditional design was confirmed. Furthermore, it has meaning in expanding the versatility of practical grafting of advanced new technology and architectural design.

Optimal Design for Strength Improvement of Support Bracket for Sanding Device of Railway Vehicle Using Topology Optimization

조연호(Yonho Cho),윤우혁(Woohyuck Yoon) Korean Society for Precision Engineering 2020 한국정밀공학회지 Vol.37 No.4

The sanding device support bracket is part of the axle box and is one of the railway vehicles parts that must withstand extremely harsh environments. Conventional welded structure type brackets were cracked at welds during operation, requiring design changes. To minimize harsh environments and manufacturing errors, this review was conducted from the design stage, and design changes were made through several trial and error. In this paper, the optimal design was derived by performing topology optimization on the model designed and manufactured through trial and error and applied to the actual vehicle. The comparison of the existing model with the empirically designed model confirmed the improvement of the optimal design using the topology optimization. The optimized design was verified by the analysis and the vibration test of IEC 61373 was satisfied. The test parts based on the optimal design were applied to the actual vehicle and the performance was verified. In the optimum design process, the shape and material as well as the weight analysis were performed and finally the brackets were designed to be light in weight and improved in strength.

Analytical design of an industrial two-term controller for optimal regulatory control of open-loop unstable processes under operational constraints

Tchamna, Rodrigue,Lee, Moonyong Elsevier 2018 ISA transactions Vol.72 No.-

<P><B>Abstract</B></P> <P>This paper proposes a novel optimization-based approach for the design of an industrial two-term proportional-integral (PI) controller for the optimal regulatory control of unstable processes subjected to three common operational constraints related to the process variable, manipulated variable and its rate of change. To derive analytical design relations, the constrained optimal control problem in the time domain was transformed into an unconstrained optimization problem in a new parameter space via an effective parameterization. The resulting optimal PI controller has been verified to yield optimal performance and stability of an open-loop unstable first-order process under operational constraints. The proposed analytical design method explicitly takes into account the operational constraints in the controller design stage and also provides useful insights into the optimal controller design. Practical procedures for designing optimal PI parameters and a feasible constraint set exclusive of complex optimization steps are also proposed. The proposed controller was compared with several other PI controllers to illustrate its performance. The robustness of the proposed controller against plant-model mismatch has also been investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Optimal regulatory control of open-loop unstable process under operational constraints. </LI> <LI> An optimization based approach to find a global optimal solution of control system. </LI> <LI> The proposed method can handle operational constraints explicitly in controller design. </LI> <LI> The analytical design offers many useful insights to process control practitioners. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>