• 제어로봇시스템학회논문지
• /
• 제9권2호
• /
• pp.168-175
• /
• 2003

A new algorithm based on Genetic Algorithms is proposed f3r solving process optimization problems formulated in MINLP, GDP and hybrid MINLP/GDP. This work is focused especially on the design of the Genetic Algorithm suitable to handle disjunctive programming with the same level of MINLP handling capability. Hybridization with the Simulated Annealing is experimented and many heuristics are adopted. Real and binary coded Genetic Algorithm initiates the global search in the entire search space and at every stage Simulated Annealing makes the candidates to climb up the local hills. Multi-Niche Crowding method is adopted as the multimodal function optimization technique. and the adaptation of probabilistic parameters and dynamic penalty systems are also implemented. New strategies to take the logical variables and constraints into consideration are proposed, as well. Various test problems selected from many fields of process systems engineering are tried and satisfactory results are obtained.

• Transactions on Electrical and Electronic Materials
• /
• 제8권1호
• /
• pp.1-4
• /
• 2007

This paper discusses two approaches for pre-polishing optimization of oxide chemical mechanical planarization (CMP) that can be used as alternatives to the commonly applied dummy structure insertion in shallow trench isolation (STI) and replacement gate (RG) technologies: reverse nitride masking (RNM) and oxide etchback (OEB). Wafers have been produced using each optimization technique and CMP tests have been performed. Dishing, erosion and global planarity have been investigated with the help of conductive atomic force microscopy (C-AFM). The results demonstrate the effectiveness of both techniques which yield excellent planarity without dummy structure related performance degradation due to capacitive coupling.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.520-525
• /
• 2003

The determination of unknown parameters in rotating machinery is a difficult task and optimization techniques represent an alternative technique for parameter identification. The Simulated Annealing(SA) and Genetic Algorithm(GA) are powerful global optimization algorithm. This paper proposes new hybrid algorithm which combined GA with SA and local search algorithm for the purpose of parameter identification. Numerical examples are also presented to verify the efficiency of proposed algorithm. And, this paper presents the general methodology based on hybrid algorithm to identify unknown bearing parameters of flexible rotors using measured unbalance responses. Numerical examples are used to ilustrate the methodology used, which is then validated experimentally.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.359-366
• /
• 2005

Most engineering optimization are based on numerical linear and nonlinear programming methods that require substantial gradient information and usually seek to improve the solution in the neighborhood of a starting point. These algorithm, however, reveal a limited approach to complicated real-world optimization problems. If there is more than one local optimum in the problem, the result may depend on the selection of an initial point, and the obtained optimal solution may not necessarily be the global optimum. This paper describes a new harmony search(HS) meta-heuristic algorithm-based approach for structural size optimization problems with continuous design variables. This recently developed HS algorithm is conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary. Two classical space truss optimization problems are presented to demonstrate the effectiveness and robustness of the HS algorithm. The results indicate that the proposed approach is a powerful search and optimization technique that may yield better solutions to structural engineering problems than those obtained using current algorithms.

• 대한기계학회논문집A
• /
• 제28권10호
• /
• pp.1558-1565
• /
• 2004

It is important to determine supporting locations for structural stability when a structure is loaded with non-uniform load or supporting locations as well as the number of the supporting structures are restricted by the problem of space. Moreover, the supporting location optimization of complex structure in real world is frequently faced with discontinuous design space. Therefore, the traditional optimization methods based on derivative are not suitable Whereas, Genetic Algorithm (CA) based on stochastic search technique is a very robust and general method. The KSTAR in-vessel control coil installed in vacuum vessel is loaded with non- uniform electro-magnetic load and supporting locations are restricted by the problem of space. This paper shows the supporting location optimization for structural stability of the in-vessel control coil. Optimization has been performed by means of a developed program. It consists of a Finite Element Analysis interfaced with a Genetic Algorithm. In addition, this paper presents an algorithm to find an optimum solution in discontinuous space using continuous design variables.

• 한국전산구조공학회논문집
• /
• 제15권3호
• /
• pp.453-462
• /
• 2002

건설공사의 설계와 시공에서 표준화된 이산형 강재단면을 이용하고 있으나, 대부분의 최적화기법에서는 표준강재단면을 사용하기 위해 별도의 이산화 과정을 가지게 되므로 설계결과의 최적성을 보장할 수 없다. 따라서, 본 논문에서는 제안된 알고리즘의 효율성을 높이기 위해 전체구조계와 구조요소계로 나누는 다단계 알고리즘을 적용하였다 수치해석 과정의 효율성과 최적해의 정확성을 예제를 통하여 비교·검토하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1095-1098
• /
• 2005

Most electronic chassis control systems until today have been designed with optimization on its own performance. However, According to the increase of the interest regarding a vehicle safety and development of information technique, the integration technique of current chassis systems is being emphasized. Each enterprise proposed it with name of GCC(Global Chassis Control) or UCC(Unified Chassis Control). This study realizes control algorithm of suspension and brake by using the vehicle model of low degree of freedom as the primary stage of realization of integrated chassis control system. The proposed algorithm build the simulation environment connected to the CarSim having full vehicle model of 27 degree of freedom for raising the thrust of results

• 한국시뮬레이션학회:학술대회논문집
• /
• 한국시뮬레이션학회 2003년도 추계학술대회 및 정기총회
• /
• pp.201-206
• /
• 2003

In clinical practice, CT Angiography is a powerful technique for the visualziation of blood flow in arterial vessels throughout the body. However CT Angiography images of blood vessels anywhere in the body may be fuzzy if the patient moves during the exam. In this paper, we propose a novel technique for removing global motion artifacts in the 3D space. The proposed methods are based on the two key ideas as follows. First, the method involves the extraction of a set of feature points by using a 3D edge detection technique based on image gradient of the mask volume where enhanced vessels cannot be expected to appear, Second, the corresponding set of feature points in the contrast volume are determined by correlation-based registration. The proposed method has been successfully applied to pre- and post-contrast CTA brain dataset. Since the registration for motion correction estimates correlation between feature points extracted from skull area in mask and contrast volume, it offers an accelerated technique to accurately visualize blood vessels of the brain.

• Journal of Mechanical Science and Technology
• /
• 제18권7호
• /
• pp.1121-1130
• /
• 2004

The Genetic Algorithm (GA), an optimization technique based on the theory of natural selection, has proven to be a relatively robust means of searching for global optimum. It converges to the global optimum point without auxiliary information such as differentiation of function. In the case of a complex problem, the GA involves a large population number and requires a lot of computing time. To improve the process, this research used parallel processing with several personal computers. Parallel process technique is classified into two methods according to subpopulation's size and number. One is the fine-grained method (FGM), and the other is the coarse-grained method (CGM). This study selected the CGM as a parallel process technique because the load is equally divided among several computers. The given design domain should be reduced according to the degree of feasibility, because mechanical system problems have constraints. The reduced domain is used as an initial design domain. It is consistent with the feasible domain and the infeasible domain around feasible domain boundary. This parallel process used the Message Passing Interface library.

• 한국자동차공학회논문집
• /
• 제19권4호
• /
• pp.99-106
• /
• 2011

This paper deals with engine room layout design optimization of fuel cell electric vehicle (FCEV), which has been proposed as a potential alternative to fossil fuel depletion. Investing the great R&D efforts, the global vehicle manufacturers, especially Honda motor corporate, have shown not prototype vehicle but commercial vehicle using fuel cell in the market recently. In this paper, we analyze cooling performance and flow characteristic in the engine room of newly FCEV, in addition we suggest the optimization process for engine room layout design optimization. The two radiators in the vehicle for fuel cell stack and electronic components cooling have been analyzed and their performance are obtained in terms of cooling performance ratio (CPR). The value of CPR should always be less than one and based on criteria, we have achieved the optimum cooling performance of radiators for stack and electronic components. Aerodynamic performance is evaluated in terms of drag coefficient, improved through underbody modification using air devices.