• 시스템엔지니어링학술지
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• 제9권2호
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• pp.83-90
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• 2013

Integrated aircraft synthesis process for rapid analysis and design is described in this paper. Data flow between different analysis fields is described in details. All the data are divided into several groups according to importance and source of the data. Analysis of design requirements and certification regulations is carried out to determine baseline configuration of an aircraft. Overall design process can be divided into initial sizing, conceptual and preliminary design phases. Basic data for conceptual design are obtained from initial sizing, CAD and geometry analysis. Basic data are required input for weight, aerodynamics and propulsion analyses. Results of this analysis are used for stability and control, performance, mission, and load analysis. Feasibility of design is verified based on analysis results of each discipline. Design optimization that involves integrated process for aircraft analysis is performed to determine optimum configuration of an aircraft on a conceptual design stage. The process presented in this paper was verified to be used for light aircraft design.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.619-627
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• 2005

An initial member sections of steel structures is selected by experience of expert building structural designers. And appropriate member section is designed by repeat calculation through structural analysis. Therefore an initial assumption of member section is necessary for saving the time for structural design and is important to acquire safety of building structures. Also brace damper are generally used to prevent or decrease structural damage by its hysteretic behavior in building structures subjected to strong earthquake. Based on plastic design, the initial section of members for architectural steel structures with brace hysteretic dampers is presented and seismic effect of structural behavior by the ratio of damper stiffness to structural story stiffness is estimated in this paper.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.61-68
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• 2000

In general, the design of membrane structures takes three steps. The first is shape finding analysis which is determination of initial equilibrium geometry with uniform stresses. The second step involve the computation of the stress-deformation to get completed membrane under various load conditions. The third step is to divide the membrane structures into several plan strips from the initial equilibrium states. This procedure is needed because of the initial shape has usually undevelopable curved surface and is called as "cutting patterns generation". By introducing this work, the deformation due to the initial stress is removed and approximate cutting patterns are generated. In this approach, however, material properties is not considered, therefore the error between the design stresses and actual stresses during the fabrication of plan strips should be occurred. In this paper, actual equilibrium shape analysis procedure for HP shape models is presented. The deviations of stresses between the design stresses and actual stresses are estimated.

• 대한토목학회논문집
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• 제8권2호
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• pp.205-213
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• 1988

사장교는 그 설계에 있어서 케이블의 개수와 배치형식, 케이블의 초기인장력, 주탑의 지지형식과 높이 등 거어더와 주탑 단면외에도 설계변수가 많으므로 효율적인 설계를 하는 것이 쉽지 않다. 본 연구에서 케이블의 초기인장력, 거어더와 주탑의 단면, 주탑의 높이를 설계변수로 하여 사장교의 설계를 최적화하는 문제를 다루었다. 서로 상호작용을 하는 여러 설계변수를 동시에 최적화하는 어려움을 피하기 위하여 본 논문에서는 초기인장력, 단면, 주탑의 좌표를 각각 독립된 설계공간에서 최적화하였다. 목적함수로서는 초기인장력 공간에서는 전체구조의 변형에너지를, 단면 및 좌표의 공간에서는 재료의 총중량을 취하였다. 제약조건으로는 초기인장력의 상하한계, 부재의 좌굴을 고려한 응력, 단면적의 하한계를 고려하였다. 대표적인 Fan형 및 Harp형 사장교를 최적설계한 결과, 제시된 방법에 의하여 합리적인 결과를 얻을 수 있음을 보이고, 기존의 최적화에서 고려하지 않았던 좌표의 최적화를 통하여 경제성을 얻을 수 있다는 것을 밝혔다.

• 한국정밀공학회지
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• 제31권5호
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• pp.411-416
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• 2014

In this research we present design optimization methods for a vehicle-mounted satellite antenna positioner. Our initial antenna positioner was conservatively designed to satisfy a worst case scenario where wind blew across the positioner at the speed of 120 km/h. Investigating stresses and safety based on Finite Element Methods (FEM), we find reflector support frames can be optimized to significantly reduce the weight of the positioner system. Thus, we optimize the reflector support frame from the given initial design while considering weight, maximum stress, maximum allowable deflection, cross section, and thickness. As a result, Shape C and the thickness of 2 mm are determined for the cross section of the reflector support frame. Applying this result, the weight of the new antenna positioner is 57.343 kg, which is decreased by 10.74% compared to the initial conservative design.

• 한국광학회지
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• 제8권3호
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• pp.175-182
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• 1997

가시광선 영역의 고분해능 3반사 망원경 광학계 설계를 위하여, 광학계의 기구적 제한사항을 만족함과 동시에 Flat Field Anastigmat 조건을 만족하는 해를 구하는 초기설계 기법이 제시되었으며, 이를 기초로 프로그램을 작성하여 F/14.5, 구경 600 mm, 시야 0.27.deg. * 1.3.deg.의 3반사 망원경광학계의 초기설계를 수행하였다. 초기 설계된 광학계의 최적화를 위하여 Code V를 사용하였으며, 그 결과로서 CCD의 모서리 부분 Field를 제외한 모든 Field에서 Nyquist Frequency에서의 MTF값이 0.5이상이었다.

• 설비공학논문집
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• 제26권8호
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• pp.357-365
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• 2014

This paper proposed a multi-objective optimization method for building energy system design using primary energy consumption and initial cost. The designing of building energy systems is a complex task, because life cycle cost and efficiency of building are determined by decisions of engineer during the early stage of design. Therefore, methods such as pareto analysis that can generate various alternatives for decision making are necessary. In this study, the optimization is performed using the NSGAII and case study was carried out for feasibility of the proposed method. As a result, alternative solutions can be obtained for the optimal building energy system design.

• Steel and Composite Structures
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• 제5권6호
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• pp.443-458
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• 2005

Steel angles are widely used in roof trusses as web and chord members and in lattice towers. Very often angle members are connected eccentrically. As a result, not only an angle member is under an axial force, but it is also subject to a pair of end eccentric moments. Moreover, the connection at each end provides some fixity so neither pinned nor the fixed end represents the reality. Many national design codes allow for the effects due to eccentricities by modifying the slenderness ratio and reducing the compressive strength of the member. However, in practice, it is difficult to determine accurately the effective length. The concept behind this method is inconsistent with strength design of members of other cross-sectional types such as I or box sections of which the buckling strength is controlled by the Perry constant or the initial imperfection parameters. This paper proposes a method for design of angle frames and trusses by the second-order analysis. The equivalent initial imperfection-to-length ratios for equal and unequal angles to compensate the negligence of initial curvatures, load eccentricities and residual stresses are determined in this paper. From the obtained results, the values of imperfection-to-length ratios are suggested for design and analysis of angle steel trusses allowing for member buckling strength based on the Perry-Robertson formula.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.127-132
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• 2005

Despite all efforts, many product development projects fail and lead to an introduction of products that do not meet customers' expectations. In general, designers usually relies upon their past experiences of similar products as a source of design knowledge when they work on a new design project. Designers need a set of practical step-by-step tools and methods which ensure a understanding of customers' needs and requirements, as well as a past design experience knowledge. In this paper we propose a design initial value module for an excavator that proposes a key initial design parameter value in an early design stage to improve a design process on Customer Requirements. It makes possible to support designers more effectively, objectively, and easily. Also it can propose better products in terms of a customer satisfaction.

• 한국철도학회논문집
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• 제12권6호
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• pp.974-982
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• 2009

본 연구는 교량/궤도 종방향 해석 및 교량/차량 동적영향을 고려한 설계기법에 대한 효율성 및 경제성을 증명하기 위하여 수행하였다. 신뢰성에 기초한 생애주기비용 최적설계는 기존 설계기법에 의한 설계, 초기비용에 기초한 최적설계, 등가 생애주기비용 최적설계에 의한 최적설계와 비교하기 위하여 5$\times$(1@50m) 경간 소수주형 교량을 대상으로 적용하였다. 신뢰성에 기초한 최적설계 결과 교량/궤도 종방향 해석 및 교량/차량 동적영향을 고려한 고속철도 교량 설계 단면이 교량/궤도 종방향 해석 및 교량/차량 동적영향을 고려하지 않은 설계 단면보다 훨씬 효율적임을 확인 하였다.