• 제목/요약/키워드: direct differentiation method

검색결과 89건 처리시간 0.024초

Seismic behavior enhancement of frame structure considering parameter sensitivity of self-centering braces

  • Xu, Longhe;Xie, Xingsi;Yan, Xintong;Li, Zhongxian
    • Structural Engineering and Mechanics
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    • 제71권1호
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    • pp.45-56
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    • 2019
  • A modified mechanical model of pre-pressed spring self-centering energy dissipation (PS-SCED) brace is proposed, and the hysteresis band is distinguished by the indication of relevant state variables. The MDOF frame system equipped with the braces is formulated in an incremental form of linear acceleration method. A multi-objective genetic algorithm (GA) based brace parameter optimization method is developed to obtain an optimal solution from the primary design scheme. Parameter sensitivities derived by the direct differentiation method are used to modify the change rate of parameters in the GA operator. A case study is conducted on a steel braced frame to illustrate the effect of brace parameters on node displacements, and validate the feasibility of the modified mechanical model. The optimization results and computational process information are compared among three cases of different strategies of parameter change as well. The accuracy is also verified by the calculation results of finite element model. This work can help the applications of PS-SCED brace optimization related to parameter sensitivity, and fulfill the systematic design procedure of PS-SCED brace-structure system with completed and prospective consequences.

중간엽줄기세포의 초자화 동결법에 의한 냉동보존 (Cryopreservation of Mesenchymal Stem Cells by Vitrification)

  • 이효종;강선영;박세진;이승용;이희천;고필옥;박지권;백원영;연성찬
    • 한국임상수의학회지
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    • 제28권4호
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    • pp.394-398
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    • 2011
  • Mesenchymal stem cells (MSC) are pluripotent cells that can be found in umbilical cord blood from new borne babies as well as placenta, bone marrow, adipose tissue, amniotic fluid, muscle, et al. MSC are capable of renewing themselves without differentiation in long-term culture, also can be differentiated into various tissues under specific condition. Formulating a cryopreservation protocol for the MSC is required because these cells cannot survive for long periods under in vitro culture conditions and a new formulation of harmless cryoprotectant is needed for the direct injection of MSC into patients. The undifferentiated MSC were frozen with a vitrification solution of 40% ethylene glycol, 20% Ficoll-70 and 0.3M sucrose. The survival rate after thawing and their proliferation rate were examined and compared with slow rate cooling methods using dimethylsulfoxide (DMSO). The vitrification method showed high survival rate after thawing and proliferation capacity comparable to DMSO. It can be suggested that ultra-rapid cooling method by vitrification is reliable methods for long term preservation of MSC and the vitrification solution with ethylene glycol, Ficoll-70 and sucrose will be more beneficially used for direct transplantation of MSC into patients than DMSO solution.

인공위성 카메라 주반사경의 위상최적화 (Topology Optimization of the Primary Mirror of a Multi-Spectral Camera)

  • 박강수;장수영;이응식;윤성기
    • 대한기계학회논문집A
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    • 제26권6호
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    • pp.1194-1202
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    • 2002
  • A study on the topology optimization of a multi-spectral camera for space-use is presented. The optimization is carried out under self-weight and polishing pressure loading. A multi-spectral camera for space-use experiences degradation of optical image in the space, which can not be detected on the optical test bench on the earth. An optical surface deformation of a primary mirror, which is a principal component of the camera system, is an important factor affecting the optical performance of the whole camera system. In this study, topology optimization of the primary mirror of the camera is presented. As an objective function, a measure of Strehl ratio is used. Total mass of the primary mirror is given as a constraint to the optimization problem. The sensitivities of the objective function and constraint are calculated by direct differentiation method. Optimization procedure is carried out by an optimality criteria method. For the light-weight primary mirror design, a three dimensional model is treated. As a preliminary example, topology optimization considering a self-weight loading is treated. In the second example, the polishing pressure is also included as a loading in the topology optimization of the mirror. Results of the optimized design topology for the mirror with various mass constraints are presented.

민감도 해석을 이용한 동적실속 제어 (Dynamic Stall Control Using Aerodynamic Sensitivity Analysis)

  • 안태술;김형진;김종암;노오현
    • 한국항공우주학회지
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    • 제30권8호
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    • pp.10-20
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    • 2002
  • 본 논문에서는 최적화 방법을 이용하여 동적 실속을 제어하는 방법을 제시하고자 한다. 비정상 공력 민감도 해석코드는 2 방정식 난류 모델을 사용한 비정상 압축성 Navier-Stokes 해석코드로부터 직접 미분법을 사용하여 개발되었다. 목적함수는 해석이 수행되는 전시간에 대한 것보다는 매 순간의 값을 사용하였다. 매 순간의 목적함수에 대한 구배값은 민감도 해석코드를 사용하여 얻었고, 최적화는 매 시간마다 간단한 건형 직선 조사방법(linear line search)을 이용하였다. 제어 변수는 익형의 노즈 반경, 최대 두께와 흡입을 사용하였다. 계산결과는 동적 실속을 제어하는데, 본 논문에서 제시한 최적화 방법이 효과적이라는 것을 보여주고 있다.

굴삭기 붐의 최적 설계 (Minimum Weight Design of the Boom of an Ecavator)

  • 임오강;신양범;이병우
    • 전산구조공학
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    • 제6권1호
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    • pp.91-98
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    • 1993
  • 굴삭기 붐의 변위와 응력 제한조건에 대해 각 판의 두께를 설계변수로 선정하여 자중을 최소화 하였다. 변위와 응력 제한조건식을 구성하기 위해 붐을 판 복합 구조물로 모델링한 후 3절점 삼각형 판요소의 유한요소 해석 프로그램으로 해석하여 상용 구조해석 프로그램인 ANSYS결과와 비교 검토하였다. 유한요소 해석 결과로부터 구성된 변위와 응력 제한조건을 직접 미분법으로 민감도를 해석하고 차분결과를 기준으로 검토하였다. 최종적으로 민감도 해석 프로그램과 최적화 알고리즘을 결합하여 판의 최적설계 프로그램을 구성하고 균일응력의 외팔보 문제로써 해외 정확도를 검증하였다. 굴삭기 붐에 대한 자중 최소화를 수행한 결과, 붐의 반쪽 모델의 초기무게가 453kgf이었고 최적설계 결과가 331kgf로서 약 27%의 자중 감소 효과를 가져왔다.

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인공위성 카메라 주반사경의 위상 최적화 (Topology Optimization of the Primary Mirror of a Multi-Spectral Camera)

  • 박강수;장수영;이응식;윤성기
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집A
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    • pp.920-925
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    • 2001
  • A study on the topology optimization of a multi-spectral camera for space-use is presented. A multi-spectral camera for space-use experiences degradation of optical image in the space, which can not be detected on the optical test bench on the earth. An optical surface deformation of a primary mirror, which is a principal component of the camera system, under the self-weight loading is an important factor affecting the optical performance of the whole camera system. In this study, topology optimization of the primary mirror of the camera is presented. Total mass of the primary mirror is given as a constraint to the optimization problem. The sensitivities of the objective function and constraint are calculated by direct differentiation method. Optimization procedure is carried out by an optimality criterion method using the sensitivities of the objective function and the constraint. As a preliminary example, topology optimization considering a self-weight loading is treated. For practical use, the polishing pressure is included as a loading in the topology optimization of the primary mirror. Results of the optimized design topology for the primary mirror with varying mass ratios are presented.

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과도상태 설계민감도를 이용한 유도가열코일의 최적설계 (Optimal Design of the Induction Heating Coil using Transient Design Sensitivity Analysis)

  • 곽인구;변진규;최경;한송엽
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제49권5호
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    • pp.327-337
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    • 2000
  • In this paper, the design sensitivity formula for the control of the transient temperature distribution is developed using the direct differentiation method, and used for the optimal design of induction heating coil position. The temperature distribution is calculated using the heat source of the induced eddy current and heat diffusion equation. The physical property variations of the workpiece depending on the temperature are considered. The eddy current distribution and the temperature distribution are calculated with the 2D finite element procedure. The adjoint variable technique is employed in expressing the design sensitivity. The goal of the design is to have the desired distribution of the temperature on a specific region of the sensitivity. The goal of the design is to have the desired distribution of the temperature on a specific region sensitivity. The goal of the design is to have the desired distribution of the temperature on a specific region of the workpiece. The numerical example shows that the proposed design sensitivity analysis for the control of the transient temperature distribution is very useful and practical in the optimal design of induction heating coils.

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건설분쟁 중재제도의 차별화 및 개선방안에 관한 연구 (A Study on Differentiation and Improvement in Arbitration Systems in Construction Disputes)

  • 이선재
    • 한국중재학회지:중재연구
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    • 제29권2호
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    • pp.239-282
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    • 2019
  • The importance of ADR(Alternative Dispute Resolution), which has the advantage of expertise, speed and neutrality due to the increase of arbitration cases due to domestic and foreign construction disputes, has emerged. Therefore, in order for the nation's arbitration system and the arbitration Organization to jump into the ranks of advanced international mediators, it is necessary to research the characteristics and advantages of these arbitration Organization through a study of prior domestic and foreign research and operation of international arbitration Organization. As a problem, First, education for the efficient promotion of arbitrators (compulsory education, maintenance education, specialized education, seminars, etc.). second, The effectiveness of arbitration in resolving construction disputes (hearing methods, composition of the tribunal, and speed). third, The issue of flexibility and diversity of arbitration solutions (the real problem of methodologies such as mediation and arbitration) needs to be drawn on the Arbitration laws and practical problems, such as laws, rules and guidelines. Therefore, Identify the problems presented in the preceding literature and diagnosis of the defects and problems of the KCAB by drawing features and benefits from the arbitration system operated by the international arbitration Institution. As an improvement, the results of an empirical analysis are derived for "arbitrator" simultaneously through a recognition survey. As a method of improvement, First, as an optimal combination of arbitration hearing and judgment in the settlement of construction disputes,(to improve speed). (1) A plan to improve the composition of the audit department according to the complexity, specificity, and magnification of the arbitration cases - (1)Methods to cope with the increased role of the non-lawyer(Specialist, technical expert). (2)Securing technical mediators for each specialized expert according to the large and special corporation arbitration cases. (2) Improving the method of writing by area of the arbitration guidelines, second, Introduction of the intensive hearing system for psychological efficiency and the institutional improvement plan (1) Problems of optimizing the arbitration decision hearing procedure and resolution of arbitration, and (2) Problems of the management of technical arbitrators of arbitration tribunals. (1)A plan to expand hearing work of technical arbitrator(Review on the introduction of the Assistant System as a member of the arbitration tribunals). (2)Improved use of alternative appraisers by tribunals(cost analysis and utilization of the specialized institution for calculating construction costs), Direct management of technical arbitrators : A Study on the Improvement of the Assessment Reliability of the Appraisal and the Appraisal Period. third, Improvement of expert committee system and new method, (1) Creating a non-executive technical committee : Special technology affairs, etc.(Major, supports pre-qualification of special events and coordinating work between parties). (2) Expanding the standing committee.(Added expert technicians : important, special, large affairs / pre-consultations, pre-coordination and mediation-arbitration). This has been shown to be an improvement. In addition, institutional differentiation to enhance the flexibility and diversity of arbitration. In addition, as an institutional differentiation to enhance the flexibility and diversity of arbitration, First, The options for "Med-Arb", "Arb-Med" and "Arb-Med-Arb" are selected. second, By revising the Agreement Act [Article 28, 2 (Agreement on Dispute Resolution)], which is to be amended by the National Parties, the revision of the arbitration settlement clause under the Act, to expand the method to resolve arbitration. third, 2017.6.28. Measures to strengthen the status role and activities of expert technical arbitrators under enforcement, such as the Act on Promotion of Interestments Industry and the Information of Enforcement Decree. Fourth, a measure to increase the role of expert technical Arbitrators by enacting laws on the promotion of the arbitration industry is needed. Especially, the establishment of the Act on Promotion of Intermediation Industry should be established as an international arbitration agency for the arbitration system. Therefore, it proposes a study of improvement and differentiation measures in the details and a policy, legal and institutional improvement and legislation.

관수로 부정류 마찰항 보정을 위한 Levenberg Marquardt 방법의 적용연구 (Application of Levenberg Marquardt Method for Calibration of Unsteady Friction Model for a Pipeline System)

  • 박조은;김상현
    • 한국수자원학회논문집
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    • 제46권4호
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    • pp.389-400
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    • 2013
  • 이 논문에서는 관망시스템의 마찰항을 보정하기 위해서, 부정류 마찰 모형과 Levenberg Marquardt 방법을 합성하였다. 부정류 마찰항을 고려하기 위한 방법으로 빈도 의존 마찰항을 사용하였으며, 특성선 방법을 모형 개발의 기반으로 하였다. 최적화에 필요한 Hessian과 Jacobian 행렬을 구하기위해서 수압을 직접 마찰항에 미분한 항을 계산하였으며, 특성선 방법상에서의 다양한 수압과 유량에 대한 마찰계수의 민감도를 수식으로 유도하였다. 간단한 관망을 가정한 뒤, 갑작스런 밸브의 거동으로 도입된수압의 시계열을 확보하였고, 이를 이용하여 정상류 마찰 모형과 부정류 마찰모형의 마찰항 보정을 수행하였다. 제안된 방법과 진화 연산 알고리즘의 마찰항 수렴거동을 비교하였으며, Leveberg Marquardt 방법의 안정적이고 신속한 수렴결과를 확인하였다.

조직배양으로 Kalanchoe pinnata의 직접기관분화를 유도하기 위한 호르몬 연구 (Hormonal Study to Induce Direct Organ Differentiation of Kalanchoe pinnata by Tissue Culture)

  • 김동균
    • 문화기술의 융합
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    • 제7권4호
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    • pp.721-726
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    • 2021
  • 식물 세포는 각 세포가 발생을 통해 새로운 완전한 개체를 생산하는 전형성능이 있다. 이것을 응용하여 식물의 증식 방법으로 기내에서 호르몬을 처리하여 체세포 배 발생의 광범위한 적용으로 여러 기술이 발전하고 있다. 이 기술을 이용하기 위해서 보다 규칙적인 세포 분열을 하는 무성생식이 가능한 식물인 Kalanchoe pinnata 에 cytokinin에 속하는 kinetin과 auxin에 속하는 호르몬들 중 picloram을 서로 조합하여 첨가한 뒤 8주 동안 처리한 후 전형성능을 실험하였다. 우리의 실험 결과로 잎 절편에서 발근 효과로는 picloram 농도가 0.1 mg/L에서 70%의 발생율을 보였다. kinetin과 picloram의 비율이 1:5-1:10의 농도차이가 효과적이라는 것이 입증 되었다. auxin의 효과가 Kalanchoe 뿌리 발생에 필수적이라는 실험 결과이다. 경엽부 발생 효과로는 picloram 농도가 0.5 mg/L에서 60%의 발생율을 보였다. kinetin 농도는 0.5 - 1.0 mg/L이며 발생에 중요한 영향을 준다. kinetin과 picloram의 비율이 1:1-1:2의 농도 차이가 효과적이라는 것이 입증 되었다. cytokinin과 auxin의 조합이 결정적으로 경엽부 발생에 중요하다는 것을 보여 주는 결과이다. 호르몬의 조합으로 직접기관형성을 유도하여 기내에서 대량 증식을 유도하는 기술의 기초가 될 수 있다고 사료된다.