• 대한기계학회논문집A
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• 제26권2호
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• pp.406-414
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• 2002

A new approach, referred to as a successive zooming genetic algorithm (SZGA), is Proposed for identifying a global solution for continuous optimization problems. In order to improve the local fine-tuning capability of GA, we introduced a new method whereby the search space is zoomed around the design point with the best fitness per 100 generation. Furthermore, the reliability of the optimized solution is determined based on the theory of probability. To demonstrate the superiority of the proposed algorithm, a simple genetic algorithm, micro genetic algorithm, and the proposed algorithm were tested as regards for the minimization of a multiminima function as well as simple functions. The results confirmed that the proposed SZGA significantly improved the ability of the algorithm to identify a precise global minimum. As an example of structural optimization, the SZGA was applied to the optimal location of support points for weight minimization in the radial gate of a dam structure. The proposed algorithm identified a more exact optimum value than the standard genetic algorithms.

• 한국산학기술학회논문지
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• 제16권1호
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• pp.97-105
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• 2015

다중반응표면 최적화는 다수의 반응변수(품질특성치)를 최적화하는 입력변수의 조건을 찾는 것을 목적으로 한다. 다중반응표면 최적화를 위해 제안된 가중평균제곱오차(Weighted Mean Squared Error, WMSE) 최소화법은 평균제곱오차의 구성요소인 제곱편차와 분산에 서로 다른 가중치를 부여하는 방법이다. 지금까지 WMSE 최소화법과 관련하여, 개별 반응변수의 WMSE를 구성한 후 이들의 가중합을 최소화하는 가중합 기반 WMSE 최소화법이 제안되었다. 그러나 가중합 기반법은 목적함수 공간에서 볼록하지 않은 구간이 있고 이 구간에서 가장 선호되는 해가 존재할 경우 이 해를 찾아내지 못한다는 한계를 지니고 있다. 본 논문에서는 기존의 가중합 기반법의 한계점을 극복하기 위하여 Tchebycheff Metric 기반 WMSE 최소화법을 제안하고자 한다.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.216-216
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• 1997

We developed the durability estimation and design systems to minimize the volume, considering the durability, efficiency, and design requirements of worm gears. That is, we consider each kind of factors affecting on durability on the basis of AGMA Standard for the cylindrical and double-enveloping worm gears. We also estimate input power on the basis of wear and durability, bending strength and deflection of worm shaft, and we developed the durability estimation and design systems of power transmission worm gears introducing the optimal design method on the personal computer to be easily used in field. Also, we developed a method which converts the design variables obtained from the optimal design method to integer values(number of worm threads, number of worm threads, number of worm wheel teeth, etc.,) to be used in real design and production. The developed durability estimation and design method can be easily applied to the design of worm gears used as power transmission devices in machineries and is expected to be used for weight minimization of worm gear unit.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 추계공동학술대회논문집
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• pp.169-174
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• 2002

방향구속 전력최소화법(Directionally Constrained Minimization of Power : DCMP)과 제로포싱방법(Zero Forcing : ZF)은 어레이 안테나에 수신된 신호들로부터 채널응답 백터인 Spatial Signature를 추정하고, 이를 이용하여 최적웨이트(Optimal Weight)를 결정함으로써 어레이 출력SINR(Signal to Interference plus Noise Ratio)을 향상시킬 수 있는 알고리즘들로 알려져 있다. 본 논문에서는 이 동국 주변에서 다중산란된 수신신호들이 어레이 안테나에 수신되는 환경에서 DCMP와 ZF방법의 성능을 분석하였다. 이를 위하여 ESPRIT를 이용하여 수신신호들의 도래각(Direction of Arrival: DOA)과 확산각도(Angular Spread: AS)를 추정하여 Spatial Signature를 구한 후, 그 결과치를 이용하여 DCMP와 ZF방법으로 어레이 출력신호를 합성하였다. 모의 실험을 통하여 어레이 출력 SINR 성능을 평가하고 이론저거 성능결과와 비교하였다.

• Preventive Nutrition and Food Science
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• 제12권4호
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• pp.222-228
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• 2007

This study was conducted to investigate the minimization of off-flavor occurrence and the maintenance of high quality in modified atmosphere packaged Pleurotus ostreatus during the storage. There are 4 treatments used to preserve high quality and for deodorization of MAP mushroom: Artemisia princeps, Artemisia capillaries, green tea and activated charcoal. The mushrooms were packed in polyethylene film with each treatment and were stored at 5 and $20^{circ}C$. No difference was observed in weight loss, $CO_2\;and\;O_2$ concentration, or color of mushrooms packed with or without treatment. However, the principal component analysis (PCA), electronic nose, revealed differences in off-flavor occurrence between control (MAP mushroom without treatment) and treatment groups at $5^{\circ}C$. This result suggested that Artemisia princeps and Artemisia capillaries was masking the off-flavor in MAP mushroom because the unique flavor of them was strongly revealed and green tea and activated charcoal might have a role of removing the off-flavor by adsorbing ethanol and acetaldehyde, which is known to cause off-flavor. The sensory test showed that Artemisia princeps and Artemisia capillaries dough treatment inhibited microbial growth.

• Journal of Communications and Networks
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• 제18권3호
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• pp.411-419
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• 2016

This article investigates the problem of distributed channel selection in opportunistic spectrum access networks from a perspective of interference minimization. The traditional physical (PHY)-layer interference model is for information theoretic analysis. When practical multiple access mechanisms are considered, the recently developed binary medium access control (MAC)-layer interference model in the previous work is more useful, in which the experienced interference of a user is defined as the number of competing users. However, the binary model is not accurate in mathematics analysis with poor achievable performance. Therefore, we propose a real-valued one called stochastic MAC-layer interference model, where the utility of a player is defined as a function of the aggregate weight of the stochastic interference of competing neighbors. Then, the distributed channel selection problem in the stochastic MAC-layer interference model is formulated as a weighted stochastic MAC-layer interference minimization game and we proved that the game is an exact potential game which exists one pure strategy Nash equilibrium point at least. By using the proposed stochastic learning-automata based uncoupled algorithm with heterogeneous learning parameter (SLA-H), we can achieve suboptimal convergence averagely and this result can be verified in the simulation. Moreover, the simulated results also prove that the proposed stochastic model can achieve higher throughput performance and faster convergence behavior than the binary one.

• Advances in Computational Design
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• 제8권4호
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• pp.327-351
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• 2023

This article explores how multi-objective optimization techniques can be used to design cost-effective and structurally optimal spatial steel structures, highlighting that optimizing performance can be as important as minimizing costs in real-world engineering problems. The study includes the minimization of maximum horizontal displacement, the maximization of the first natural frequency of vibration, the maximization of the critical load factor concerning the first global buckling mode of the structure, and weight minimization as the objectives. Additionally, it outlines a systematic approach to selecting the best design by employing four different evolutionary algorithms based on differential evolution and a multi-criteria decision-making methodology. The paper's contribution lies in its comprehensive consideration of multiple conflicting objectives and its novel approach to simultaneous consideration of bracing system, column orientation, and commercial profiles as design variables.

• 대한토목학회논문집
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• 제34권4호
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• pp.1261-1267
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• 2014

철도노선은 도로노선과 달리 운행비용, 특히 에너지비용이 전체 생애주기 비용에서 차지하는 비중이 높은 것으로 알려져 있다. 본 연구에서는 경부고속철도의 사례를 중심으로 철도 노반건설비와 에너지비용의 상대적 비중을 분석하였다. 이는 최근 활발하게 연구가 이루어지고 있는 전산화된 철도선형 최적화가 단순히 건설비 최소화만을 목적으로 할 수 없으며, 에너지 비용을 포함한 전반적인 생애주기 비용의 최소화를 목표로 하여야 함을 의미한다. 경부고속철도 운행실적이 아직 10년에 불과하기 때문에 향후 20년간의 운영 시나리오를 다양하게 설정하여 분석한 결과, 에너지비용이 건설비용의 10~30% 수준으로 나타났으며, 이는 일반적으로 알려진 비중보다 낮은 수치이다. 철도 선형 최적화를 위한 방법론 정립에 있어 에너지 비용을 고려할 경우, 그 상대적 비중을 고려할 수 있는 방안을 제시한데 본 연구의 의미가 있을 것이다.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.122-130
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• 2001

In this paper, an operational algorithm for a 2-shaft parallel hybrid electric vehicle is suggested for the minimization of operation cost. The operation cost is obtained as a summation of the engine fuel cost and the motor electricity cost. The electrical cost function is estimated in case of motoring, and generating when the recuperation is carried out during the braking. In addition, weight function is introduced in order to maintain the battery state of charge. Based on the operation algorithm, the optimal engine operation point that minimizes the operation cost is obtained with respect to the required vehicle power for every state of charge of battery. The optimal operation point provides the optimal power distribution of the engine and the motor for a required vehicle power Simulation was performed and the fuel economy of the hybrid vehicle was compared to that of the conventional vehicle. Simulation results showed that hybrid vehicle's fuel economy can be improved as much as 45∼48% compared to the conventional vehicle's.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.510-515
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• 2003

The main objective of this paper is to propose the optimal design method of welded plate girder bridges using genetic algorithm. The objective function considered is the total weight of the welded plate girder. The behavior and design constraints are formulated based on the Korean Railroad Bridge Design Code and DIC Code. Continuous design variables are used to define the cross-sectional dimensions of the member. The GAs (genetic algorithm) is used to solve the nonlinear programming problem. Several examples of minimum weight design are solved to illustrate the applicability of the proposed minimization algorithm. From the results of application examples, the optimum design of welded plate girder is successfully accomplished. Therefore, the proposed algorithm in this paper may be used efficiently and generally for the optimum design of welded plate girders.