• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.396-396
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• 2000

Multiperiod optimization is the key step to tackle the supply chain optimization problems. Taking supply and demand uncertainty or prediction into consideration during the process synthesis phase leads to the maximization of the profit for the long range time horizon. In this study, new algorithm based on the Genetic Algorithms is proposed for multiperiod optimization formulated in MINLP, GDP and hybrid MINLP/GDP. In this study, the focus is given 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 tried. and many heuristics are adopted for this purpose.

• 한국미생물·생명공학회지
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• 제19권3호
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• pp.281-289
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• 1991

Neurospora crassa는 성장이 끝나고 분화되는 과정에서 tyrosinase를 생산하며 아미노산류의 기질유사체, 반대사물질, 단백질 생합성 저해제 등에 의해 효소생산이 유도된다. 미생물 균체를 배양시키며 여러가지 유도물질을 사용하여 효소의 생합성을 유도시킨 결과 가장 적합한 유도물질은 cycloheximide였다. 이는 균체의 성장을 크게 저해하는 항생제의 일종이므로 효소 생합성을 최대화시키기 위한 최적의 농도가 존재하였으며, 유도물질의 농도가 일정한 경우에 효소 생산에 최적인 유도시간이 존재하였다.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.877-885
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• 2018

Various controllers such as proportional-integral-derivative (PID) controllers have been designed and optimized for load-following issues in nuclear reactors. To achieve high performance, gain tuning is of great importance in PID controllers. In this work, gains of a PID controller are optimized for power-level control of a typical pressurized water reactor using particle swarm optimization (PSO) algorithm. The point kinetic is used as a reactor power model. In PSO, the objective (cost) function defined by decision variables including overshoot, settling time, and stabilization time (stability condition) must be minimized (optimized). Stability condition is guaranteed by Lyapunov synthesis. The simulation results demonstrated good stability and high performance of the closed-loop PSO-PID controller to response power demand.

• 한국광학회지
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• 제20권6호
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• pp.319-327
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• 2009

본 논문에서는 다음과 같은 관점의 광각 2군 줌 렌즈 설계를 소개한다. 먼저전역최적화의 개념을 기초설계단계에서 도입하고, 이를 통해 현대의 수많은 데이터들을 체계적으로 계통화하고 단순화할 수 있는 설계방안을 제안한다. 구체적인 방안으로 전역설 계를 위해 전역구조함수라는 새로운 개념의 함수를 도입하였고 단순화시켰으며, 나아가 약간의 대수적인 혹은 수치적인 계산을 통해 전역 해 영역을 구하였다. 전역 해 영역은 전역최적화에 대응되는 개념이고 상용화된 설계프로그램들 보다 더 체계적이고 통찰적인 설계방향을 제시한다.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.940-947
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• 2022

Meta-heuristic algorithms have found their place in optimization problems. Henry gas solubility optimization (HGSO) is one of the newest population-based algorithms. This algorithm is inspired by Henry's law of physics. To evaluate the performance of a new algorithm, it must be used in various problems. On the other hand, the optimization of the proportional-integral-derivative (PID) gains for load-following of a nuclear power plant (NPP) is a good challenge to assess the performance of HGSO. Accordingly, the power control of a pressurized water reactor (PWR) is targeted, based on the point kinetics model with six groups of delayed-neutron precursors. In any optimization problem based on meta-heuristic algorithms, an efficient objective function is required. Therefore, the integral of the time-weighted square error (ITSE) performance index is utilized as the objective (cost) function of HGSO, which is constrained by a stability criterion in steady-state operations. A Lyapunov approach guarantees this stability. The results show that this method provides superior results compared to an empirically tuned PID controller with the least error. It also achieves good accuracy compared to an established GA-tuned PID controller.

• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1072-1079
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• 2005

Conceptual design is the first step in the overall process of product design. Its intrinsic uncertainty, imprecision, and lack of information lead to the fact that current conceptual design activities in engineering have not been computerized and very few CAD systems are available to support conceptual design. In most of the current intelligent design systems, approach of principle synthesis, such as morphology matrix, bond graphic, or design catalogues, is usually adopted to deal with the concept generation, in which optional concepts are generally combined and enumerated through function analysis. However, as a large number of concepts are generated, it is difficult to evaluate and optimize these design candidates using regular algorithm. It is necessary to develop a new approach or a tool to solve the concept generation. Generally speaking, concept generation is a problem of concept synthesis. In substance, this process of developing design candidate is a combinatorial optimization process, viz., the process of concept generation can be regarded as a solution for a state-place composed of multi-concepts. In this paper, genetic algorithm is utilized as a feasible tool to solve the problem of combinatorial optimization in concept generation, in which the encoding method of morphology matrix based on function analysis is applied, and a sequence of optimal concepts are generated through the search and iterative process which is controlled by genetic operators, including selection, crossover, mutation, and reproduction in GA. Several crucial problems on GA are discussed in this paper, such as the calculation of fitness value and the criteria for heredity termination, which have a heavy effect on selection of better concepts. The feasibility and intellectualization of the proposed approach are demonstrated with an engineering case. In this work concept generation is implemented using GA, which can facilitate not only generating several better concepts, but also selecting the best concept. Thus optimal concepts can be conveniently developed and design efficiency can be greatly improved.

• 한국항공우주학회지
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• 제40권8호
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• pp.695-702
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• 2012

본 연구에서는 개념설계 단계에서의 해석 결과의 정확도를 높이기 위한 다정밀도 해석과 모든 분야의 요구도를 만족하기 위한 다분야통합 설계 최적화 기법을 적용하였다. 무인항공기의 해석을 위하여 경험식 기반의 저정밀도 해석도구들이 초기 사이징, 공력, 추진, 임무, 중량, 성능, 안정성 도구들로 모듈화되어 개발 및 검증되었다. 개발된 해석도구를 이용하여 설계통합 프로그램을 구성하고, 설계의 정확도를 증가시키기 위하여 다정밀도 해석에 와류 격자법을 이용하였다. 다분야통합 설계 최적화를 위하여 MDF 기법이 적용되었다. 또한 최적화 도구로는 구배기반 최적화 기법을 적용하였다. 제시한 방법의 타당성을 밝히기 위하여, 저정밀도 해석만을 적용한 방법과 다정밀도 해석을 적용한 두 가지 방법의 최적화 결과를 비교하여 본 연구에서 제안된 다정밀도 해석이 개념설계 단계에서 적용 가능함을 보였다.

• Environmental Engineering Research
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• 제19권4호
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• pp.339-344
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• 2014

Different types of polyethersulfone (PES) support layer for a thin film composite (TFC) membrane were synthesized under various synthesis conditions using the phase inversion method to study the combined effects of substrate, adhesive, and pore former. The permeability, selectivity, pore structure, and morphology of the prepared membranes were analyzed to evaluate the membrane performance. The combined use of substrate, adhesive, and pore former produced a thinner dense top layer, with more straight finger-like pores. The pure water permeation (PWP) of the optimized PES membrane was $27.42L/m^2hr$ (LMH), whereas that of bare PES membrane was 3.24 LMH. Moreover, membrane selectivity, represented as divalent ion ($CaSO_4$) rejection, was not sacrificed under the synthesis conditions, which produced the dramatically enhanced PWP. The high permeability and selectivity of the PES membrane produced under the optimized synthesis conditions suggest that it can be utilized as a potential support layer for TFC membranes.

• 대한기계학회논문집
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• 제17권6호
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• pp.1330-1341
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• 1993

본 연구에서는 회전대우(revolute joint)들로 이루어진 1자유도 평면기구들의 특성을 파악하고 그래이프이론(graph theory)을 이용하여 기구의 형태를 행렬로 표시 하여 체이터베이스에 저장하였다. 또한 기구의 특성중의 하나인 작업조건(function specification)에 따른 무오차점(precision point)의 최대 개수를 알아내는 프로그램 을 개발하여 이로써 얻은 정보를 또 다른 데이타베이스에 저장하였다. 이와같이 구축 된 데이터베이스들로부터 설계자의 요구에 적합한 기구를 선택하여 형태합성 문제를 해결하였다.

• Korean Chemical Engineering Research
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• 제61권2호
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• pp.322-327
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• 2023

A design of experiments was evaluated in optimizing MOF-5 synthesis for acetylene adsorption. At first, mixture design was used to optimize precursor concentration, terephthalic acid, zinc acetate dihydrate and N,N-dimethylformamide. More specifically, 13 conditions with various molar ratios were designed by extreme vertices design method. After preparing the samples, XRD, N₂ physisorption and SEM analysis were performed for their characterization. Moreover, acetylene adsorption experiments were carried out over the samples under identical conditions. The optimal precursor composition for MOF-5 synthesis was predicted on a molar basis as follows: terephthalic acid : acetate dihydrate : dimethylformamide = 0.1 : 0.4 : 0.5. Thereafter, multi-level factorial design was designated to investigate the effect of synthesis reaction conditions such as temperature, time and stirring speed. By the statistical analysis of 18 samples designed, 4 reaction parameters were determined for additional adsorption experiments. Therefore, MOF-5 prepared under the synthesis time and temperature of 100 ℃ and 12 h, respectively, showed the maximum adsorption capacity of 15.1 mmol/g.