• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.609-612
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• 2000

Job-shop scheduling problem(JSSP) is one of the best-known machine scheduling problems and essentially an ordering problem. A new encoding scheme which always give a feasible schedule is presented, by which a schedule directly corresponds to an assigned-operation ordering string. It is initialized with G&T algorithm and improved using the developed genetic operator; APMX or BPMX crossover operator and mutation operator. and the problem of infeasibility in genetic generation is naturally overcome. Within the framework of the newly designed genetic algorithm, the NP-hard classical job-shop scheduling problem can be efficiently solved with high quality. Moreover the optimal solutions of the famous benchmarks, the Fisher and Thompson's 10${\times}$10 and 20${\times}$5 problems, are found.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.381-385
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• 2003

We consider the bandwidth parking problem arising from telecommunication networks The problem is to determine the set of calls to be routed and an assignment or them to the paths in arc capacitated network. The objective is to maximize profit. We formulate the problem as an integer programming and propose an algorithm to solve it. Column generation technique to solve the linear programming relxation is proposed with two types of columns in addition, to obtain an optimum integer solution, we consider a new branching strategy. Computational experiments show that the algorithm gives option at solutions within reasonably small time limits.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.129-132
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• 1987

This paper presents an emergency control algorithms for viability crisis following abnormal condition as well as a sudden major supply outage and line outage. The algorithm considers the effect of voltage-reactive power control for determining the load shedding quantities and generation reallocation. The problem is decomposed into a P-problem and a Q-problem. The former minimizes system frequency deviation from nominal value and the latter minimizes voltages violation of load buses. The optimization problem is solved by a reduced gradient technique which can handle a great number of inequality constraints very efficiently. It has been found that the use of the proposed algorithm for 6-Bus system restore the abnormal system during the viability crisis to the normal state.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.4
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• pp.31-41
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• 2003

This paper deals with a cell formation problem for a set of m-machines and n-processing parts. Generally, a cell formation problem is known as NP-completeness. Hence the cell formation problem with multiple objectives is more difficult than single objective problem. The paper considers multiple objectives; minimize number of intercell movements, minimize intracell workload variation and minimize intercell workload variation. We propose a multiple objective genetic algorithms(MOGA) resolving the mentioned three objectives. The MOGA procedure adopted Pareto optimal solution for selection method for next generation and the concept of Euclidean distance from the ideal and negative ideal solution for fitness test of a individual. As we consider several weights, decision maker will be reflected his consideration by adjusting high weights for important objective. A numerical example is given for a comparative analysis with the results of other research.

• Journal of Agricultural Extension & Community Development
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• v.10 no.2
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• pp.239-249
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• 2003

Waste policy instruments such as garbage bag-fee system and recycling policy initiated in 1995 have contributed to the reduction of solid waste generation. Rural areas now produce less amount of solid wastes in terms of per capital than urban areas and as compare to a decade ago. However, most policy efforts since the early 1990s related to waste issue have been concentrated in urban areas. Waste problems in rural areas are not the amount itself, but the specific characteristics which are unique in rural regions. Large portion of solid wastes and farming wastes are being illegally treated and/or burned out. Surveys show that the main reasons for the illegal treatment of rural wastes are th lack of systematic policy tools targeting on them, insufficient financial capacity and man power of local governments, rural people's cognition problem about wastes, among others. This study reviews current features of the treatment of rural solid wastes and provides policy suggestions for the resolution of the problem.

• Journal of the military operations research society of Korea
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• v.26 no.1
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• pp.56-69
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• 2000

A frequency assignment problem on time division duplex system is considered. Republic of Korea Army (ROKA) has been establishing an infrastructure of tactical communication (SPIDER) system for next generation and it will be a core network structure of system. VHF system is the backbone network of SPIDER, that performs transmission of data such as voice, text and images. So, it is a significant problem finding the frequency assignment with no interference under very restricted resource environment. With a given arbitrary configuration of communications network, we find a feasible solution that guarantees communication without interference between sites and relay stations. We formulate a frequency assignment problem as an Integer Programming model, which has NP-hard complexity. To find the assignment results within a reasonable time, we take a genetic algorithm approach which represents the solution structure with available frequency order, and develop a genetic operation strategies. Computational result shows that the network configuration of SPIDER can be solved efficiently within a very short time.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.163-170
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• 2004

In order to automatically determine the sequences of block assembly operations in shipbuilding, a process planning system using case-based reasoning (CBR) is developed. A block-assembly planning problem is modeled as a constraint satisfaction problem where the precedence relations between operations are considered constraints. The process planning system generates an assembly sequence by adapting information such as solutions and constraints collected from similar cases retrieved from the case base. In order to find similar cases, the process planning system first matches the parts of the problem and the parts of each case based on their roles in the assembly, and then it matches the relations related to the parts-pairs. The part involved in more operations are considered more important. The process planning system is applied to simple examples fur verification and comparison.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.139-144
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• 2003

Mobile Node has to maintain communication as they move form place to place, so it doesn't guarantee Quality of Service(QoS). Fast Handoff is important to provide multimedia and real-time applications services in mobile, and it is closely related to handoff delay. Therefore, handoff delay problem is actively studied to quarantee QoS as a main issue in mobile IP research area. Next generation Mobile IPv6 resolve this problem somewhat, triangle problem for first packet and handoff delay still remain. In this paper, we suggest SNMP Information-based routing that adds keyword management method to Information-based routing in active network in order to resolve such a problem, and then suggest QoS controlled handoff based on SNMP Information-Based routing. After modeling of suggested method and existing handoff method, simulations are carried out with NS-2 for performance evaluation. The results of simulations show the some improvement on handoff delay, and therefore on QoS improvement.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.157-162
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• 2020

In the existing photovoltaic generation system, the system equipped with the reflecting plate is a method in which solar energy (insolation) is concentrated on the surface of the photovoltaic module. However, the solar energy (insolation) lost by being reflected back through the solar module is not considered. Although a method of increasing the amount of power generated by installing a reflector around the solar modules has been proposed, this affects the power generation degradation caused by the shading of other solar modules. Therefore, in order to improve this problem, in this paper, 1) without affecting the development of photovoltaic module according to the shade, 2) photovoltaic module using a reflector rotating the solar energy (insolation) lost by the solar module Study and suggest how to join again. Therefore, the loss of solar energy (insolation) can be minimized through the method of recycling the solar energy according to the countless reflection angle of the lost solar energy (insolation). As a result, it is possible to increase the amount of power generation of the photovoltaic generation system by maximizing the amount of power generation for the same solar radiation.

• KIEE International Transactions on Power Engineering
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• v.5A no.1
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• pp.85-92
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• 2005

In this paper, Nash equilibriums of generation markets are investigated using a game theory application for simplified competitive electricity markets. We analyze the characteristics of equilibrium states in N-company spot markets modeled by uniform pricing auctions and propose a new method for obtaining Nash equilibriums of the auction. We assume that spot markets are operated as uniform pricing auctions and that each generation company submits its bids into the auction in the form of a seal-bid. Depending on the bids of generation companies, market demands are allocated to each company accordingly. The uniform pricing auction in this analysis can be formulated as a non-cooperative and static game in which generation companies correspond to players of the game. The coefficient of the bidding function of company-n is the strategy of player-n (company-n) and the payoff of player-n is defined as its profit from the uniform price auction. The solution of this game can be obtained using the concept of the non-cooperative equilibrium originating from the Nash idea. Based on the so called residual demand curve, we can derive the best response function of each generation company in the uniform pricing auction with N companies, analytically. Finally, we present an efficient means to obtain all the possible equilibrium set pairs and to examine their feasibilities as Nash equilibriums. A simple numerical example with three generation companies is demonstrated to illustrate the basic idea of the proposed methodology. From this, we can see the applicability of the proposed method to the real-world problem, even though further future analysis is required.