• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.184-184
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• 2017

A nation-wide water-energy-food (WEF) nexus simulation model has been developed by the authors and successfully applied to South Korea to predict the sustainability of those three resources in the next 30 years. The model was also capable of simulating future scenarios of resources allocation based on priority rules aiming to maximize resources sustainability. However, the process was still relying on several assumptions and trial-and-error approach, which sometimes resulted in non-optimal solutions of resources allocation. In this study, an optimization module was introduced to enhance the model in generating optimal resources management rules. The objective of the optimization was to maximize the reliability index of resources by determining the resources' allocation and/or priority rules for each demand type that accordingly reflect the resources management policies. Implementation of the optimization module would result in balanced allocation and management of limited resources and assist the stakeholders in deciding resources' management plans, either by fulfilling the domestic production or by global trading.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.1086-1092
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• 2002

Computer simulation is essential to design the suspension elements of railway vehicle. By computer simulation, engineers can assess the feasibility of a given design factors and change them to get a better design. But if one wishes to perform complex analysis on the simulation, such as railway vehicle dynamic, the computational time can become overwhelming. Therefore, many researchers have used a mega model that has a regression model made by sampling data through simulation. In this paper, the neural network is used a mega model that have twenty-nine design variables and forty-six responses. After this mega model is constructed, multi-objective optimal solutions are achieved by using the differential evolution. This paper shows that this optimization method using the neural network and the differential evolution is a very efficient tool to solve the complex optimization problem.

• 한국항공운항학회지
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• 제26권2호
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• pp.54-60
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• 2018

This paper contains the multi-mission scheduling optimization of UAV within a given operating time. Mission scheduling optimization problem is one of combinatorial optimization, and it has been shown to be NP-hard(non-deterministic polynomial-time hardness). In this problem, as the size of the problem increases, the computation time increases dramatically. So, we applied the genetic algorithm to this problem. For the application, we set the mission scenario, objective function, and constraints, and then, performed simulation with MATLAB. After 1000 case simulation, we evaluate the optimality and computing time in comparison with global optimum from MILP(Mixed Integer Linear Programming).

• 한국정밀공학회지
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• 제21권10호
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• pp.137-146
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• 2004

This is the second of two companion papers concerned with the analysis and design of a pneumatic vibration isolation system. The properties of the system are clarified by observation of the transmissibility surface calculated by the models and algorithm developed in the first paper of this research. It Is shown that the nonlinear model proposed in this research is more closer to experimental results than the linear model that have been used in previous studies. The design optimization of the major design variables that affect the performance of the system is achieved by using the condition for attenuation, disturbance rejection and maximum damping in resonance peak. The design space search method is adopted for the optimization of the orifice area. The models, transmissibility calculation algorithms and design optimization techniques developed in this research are shown to be greatly helpful to the optimal design of the pneumatic vibration isolation system by experiment.

• Journal of Power Electronics
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• 제12권2호
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• pp.368-376
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• 2012

This paper deals with an optimization approach of 3D space placement of power components under volume and thermal constraints. It consists in optimizing semiconductors positions on a heat sink by respecting the components junction temperatures and minimizing the heat sink size. The aim is to remove risks on the 3D converter components placement and ensure their effective integration before carrying out the first physical prototype. This approach is based on coupling an optimization environment with a thermal finite element simulation tool. A pre-sizing step using analytical models is performed to set the optimization computations coupled to numerical simulation.

• 대한산업공학회지
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• 제33권2호
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• pp.282-289
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• 2007

While demands for express couriers service are rapidly increasing due to recent progress of electronic commerce, express courier service companies are struggling to take a larger market share through ongoing improvement in their service processes. Cut-off time is the time limit that all orders delivered before the limit are guaranteed for the delivery within the very next day. Extending cut-off time for express service centers can provide the express company with increase of total sales, but it may also cause increasing the possibility not to satisfy customer needs due to work delay in the consolidation terminal. We develop a design model for express courier service network based on a recursive optimization/simulation procedure. With the optimization model, we seek key design parameters such as the cut-off time for express service centers and the capacity of the consolidation terminal maximizing total sales profit while satisfying the desired level of performances. With the simulation model, we consider the dynamic nature of the network and obtain relationships between the design parameters and the performance measures with the multiple linear regression. The validity of the model is examined with an example.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2006년도 추계 학술대회
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• pp.133-138
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• 2006

The problem that we address is to determine the inventory stockage levels in a multi-echelon inventory system for repairable items in a multi-indenture system. We propose the simulation optimization approach to determine the stockage levels at each echelon, where a simulator for the underlying system is combined with an appropriate optimization tool, Genetic Algorithm (GA).

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 추계학술대회 논문집
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• pp.127-132
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• 1999

A mobile IP is proposed to support host mobility over the current Internet. One of the most important issues on the host mobility is location and routing schemes that allow mobile hosts to move effectively from one site to another. In a Mobile IP environment, frequent handoffs are likely to degrade the performance by minimizing the loss of datagrams during handoffs. The handoff scheme is using routing optimization and binding extension to improve the performance by minimizing the average transfer delay of messages and packet loss. Simulation details show the improvement of transport delays and packet loss rate.

• Journal of Information Display
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• 제10권2호
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• pp.54-61
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• 2009

The results of the optimization of the organic passivation process for fabricating thin-film transistors (TFTs) with a high aperture ratio on a seventh-generation glass (2200${\times}$1870 mm) substrate for LCD-TV panels are reported herein. The optimization of the organic passivation process has been verified by checking various factors, including the material properties (e.g., thickness, stain, etching, thermal reflow) and the effects on the TFT operation (e.g., gate/data line delay and display-driving properties). The two main factors influencing the organic passivation process are the optimization of the final thickness of the organic passivation layer, and the gate electrode. In conclusion, the minimum possible final thickness was found to be $2.42{\um}m$ via simulation and pilot testing, using the full-factorial design. The optimization of the organic passivation layer was accomplished by improving its brightness by over 10 cd/$m^2$ (ca. 2% luminance) compared to that of the conventional organic passivation process. The results of this research also help reduce the reddish stain on display panels.

• 한국시뮬레이션학회논문지
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• 제27권2호
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• pp.83-90
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• 2018

본 연구에서는 선형의 기본 파라메타가 주어졌을 때, 선형 최적화를 통하여 고속으로 주행하는 활주선의 저항성능을 개선하는 기법을 제안하였다. 먼저 선행연구 된 활주선형을 기준 선형으로 채택한 뒤, 선형 변경지점을 정의해 설계변수로 하여 최적화 문제를 수립하였다. 계산 효율을 위하여 탐색공간을 이산화하고, 최적화 문제를 풀기위하여 DPSO(Discrete binary version of Particle Swarm Optimization) 알고리즘을 사용하였다. 최적화 수행 후 기준 선형과 수정 선형의 목적함수 출력의 비교를 수행하였고, 이를 통해 고속영역에서의 저항성능의 개선을 확인하였다.