• Journal of Electrical Engineering and information Science
• /
• 제2권6호
• /
• pp.28-35
• /
• 1997

A new approach concurrent transistor sizing and buffer insertion for low power optimization is proposed in this paper. The method considers the tradeoff between upsizing transistors and inserting buffers and chooses the solution with the lowest possible power and area cost. It operates by analyzing the feasible region of the cost-delay curves of the unbuffered and buffered circuits. As such the feasible region of circuits optimized by our method is extended to encompass the envelop of cost-delay curves which represent the union of the feasible regions of all buffered ad unbuffered versions of the circuit. The method is efficient and tunable in that optimality can be traded for compute time and as a result it can in theory near optimal results.

• ETRI Journal
• /
• 제38권5호
• /
• pp.941-951
• /
• 2016

In this paper, cognitive radio and simultaneous wireless information and power transfer (SWIPT) are effectively combined to design a spectrum-efficient and energy-efficient transmission paradigm. Specifically, a novel SWIPT-based primary-secondary cooperation model is proposed to increase the transmission rate of energy/spectrum constrained users. In the proposed model, a multi-antenna secondary user conducts simultaneous energy harvesting and information forwarding by means of power splitting (PS), and tries to maximize its own transmission rate under the premise of successfully assisting the data delivery of the primary user. After the problem formulation, joint power splitting and beamforming optimization algorithms for decode-and-forward and amplify-and-forward modes are presented, in which we obtain the optimal PS factor and beamforming vectors using a golden search method and dual methods. Simulation results show that the proposed SWIPTbased primary-secondary cooperation schemes can obtain a much higher level of performance than that of non-SWIPT cooperation and non-cooperation schemes.

• 한국식품저장유통학회지
• /
• 제13권5호
• /
• pp.623-628
• /
• 2006

꽃향유로부터 정유물을 추출하여 천연향료로 개발하기 위하여 수증기증류법으로 추출하고 추출공정의 최적 조건을 반응표면 분석법으로 얻고자 하였다. 수증기증류법의 추출조건에 따른 꽃향유 추출물의 품질특성으로 수율과 총페놀화합물, 전자공여능과 주요 향기성분으로 estragole 과 thymol, beta-caryophyllene의 함량을 분석하였다. 추출온도가 추출시간보다 더 큰 영향을 주는 것으로 나타났으며, 각 품질 특성에 대하여 수립된 예측모델식이 모두 유의성이 높아 각 변수의 예측이 가능함을 보였다. 실험구간내에서 능선분석을 통하여 최대점과 추출조건을 예측하였으며 품질특성 값을 최대로 하는 제한 조건으로 얻어진 최적 추출조건은 $108^{\circ}C$와 2.1시간이었다.

• Biomaterials and Biomechanics in Bioengineering
• /
• 제2권4호
• /
• pp.207-223
• /
• 2015

In this paper a method for simultaneous swift non-linear analysis and optimal design/posture of mechanical/biomechanical systems is presented. The method is developed to get advantages of iterations in non-linear analysis and/or generations in genetic algorithm (GA) for the purpose of efficient analysis within the optimal design/posture. The method is applicable for both size and geometry optimizations wherein material and geometry non-linearity are present. In addition to established mechanical systems, the method can solve biomechanical models of human musculoskeletal system. Optimization-based procedures are popular methods for resolving the redundancy at joints wherein the number of unknown muscle forces is far more than the number of equilibrium equations. These procedures involve optimization of a cost function(s) which is assumed to be consistent with the central nervous system's strategy when activating muscles to assure equilibrium. However, because of the complexity of biomechanical problems (i.e., due to non-linear biomaterial, large deformation, redundancy of the problem and so on) efficient analysis are required within optimization procedures as suggested in this paper.

• 한국정밀공학회지
• /
• 제19권10호
• /
• pp.120-129
• /
• 2002

An integrated structure and controller design approach for rotating cantilever beam is presented. An optimization method is developed for improving positioning performance considering the elastic deformations during high speed rotation and adopting the beam shape and the control gains as design variables. For this end, a dynamic model is setup by the finite element method according to the shape of the beam. The mass and stiffness of the beam are distributed in such a way that the closed-loop poles of the control system should be located leftmost in the complex s-plane. For optimization method, the simulated annealing method is employed which has higher probability to find the global minimum than the gradient-based down-hill methods. Sequential design and simultaneous design methods are proposed to obtain the optimal shape and controller. Simulations are performed with new designs by the two methods to verify the effectiveness of the approach and the results show that the settling time is improved for point-to-point position controls.

• 전산구조공학
• /
• 제9권3호
• /
• pp.179-186
• /
• 1996

본 연구에서는 구조체의 위상학적 최적화를 위한 비선형 formulation(NLP)가 개발, 검토되었다. 이 NLP는 multiple-loading하에서 임의의 오브젝티브 함수, 응력, 변위 제약조건들을 쉽게 다룰 수가 있다. 또한 이 NLP는 해석과 최적화 디자인을 동시에 실시함으로써 요소 사이즈가 영으로 접근함에 따른 강성 매트릭스의 singularity를 피할 수 있다. 즉, 평형 방정식을 등제약조건으로 치환함으로써 강성 매트릭스 그 자체나 그의 역매트릭스를 구할 필요도 없어진다. 이 NLP는 multiple-loading conditon하에서 테스트되었으며, 이를 통해 이 NLP가 다양한 제약조건하에서 강력하게 작용함이 입증되었다.

• 한국항공우주학회지
• /
• 제36권10호
• /
• pp.947-953
• /
• 2008

다분야 통합 최적설계(MDO) 프레임워크는 항공우주시스템의 설계에 고려해야 할 다양한 설계 분야의 통합적이고 동시적인 해석 및 설계 최적화를 위한 통합 환경으로 해석자원 및 최적화자원은 물론 CAD 툴과 DBMS 또한 통합해야하며 사용자편의환경을 제공해야한다. 또한 설계하고자 하는 대상 및 개발환경에 따라 프레임워크의 구축방법은 달라질 수 있다. 본 논문에서는 개발환경에 따라 단일 PC기반 프레임워크와 PLinda기반 프레임워크, 그리고 웹서비스 기반 프레임워크로 분류하여 이들을 비교 분석하였다.

• Wind and Structures
• /
• 제34권3호
• /
• pp.291-301
• /
• 2022

Although mostly used in wind turbine market, single rotor wind turbines have problems with transportation and installation costs due to their large size. In order to solve such problems, multi-rotor wind turbine is being proposed; however, light weight design of multi-rotor wind turbine is required considering the installation at offshore or deep sea. This study proposes the systematic design process of the multi-rotor wind turbine focused on its supporting structure with simultaneous consideration of static and dynamic behaviors in an ideal situation. 2D and successive 3D topology optimization process based on the density method were applied to minimize the compliance of supporting structure. To realize the conceptual design obtained by topology optimization for manufacturing feasibility, the derived 3D structure was modified to have shell structures and optimized again through parametric design using the design of experiments and the response surface method for detail design of their thicknesses and radii. The resultant structure was determined to satisfy the stress and the buckling load constraint as well as to minimize the weight and the resultant supporting structure were verified numerically.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
• /
• pp.229-233
• /
• 1990

A new on-line optimization technique of a distillation column is presented. The equation decoupling method and the simultaneous solution method are combined to simulate the distillation process. The storage requirement is small enough to run on a PC. A improved successive quadratic programming is used to find the optimum operating conditions. The optimizer is intensively tested by using the dynamic simulator, SPEEDUP. After this, the technique is applied to a binary distillation column that treats methanol and water.

• Mass Spectrometry Letters
• /
• 제5권1호
• /
• pp.30-33
• /
• 2014

A solid phase extraction (SPE) method was optimized for the quantitative analysis of perfluorooctanoic acid (PFOA) in serum using hydrophilic-lipophilic balance SPE and LC-MS/MS. Fetal bovine serums spiked with $^{13}C_8$-PFOA before or after SPE were used as test samples for evaluation of the SPE efficiency. Simultaneous evaluation of matrix effects and absolute SPE recovery for $^{13}C_8$-PFOA in serum using different sample pre-treatments and SPE conditions allowed optimization of SPE process efficiency with minimal matrix effect and decent SPE recovery. Introduction of protein precipitation as a sample pre-treatment procedure for serum samples before SPE generally decreased matrix effect in LC-MS/MS analysis and provided more stable recovery of PFOA.