• Korean Management Science Review
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• v.12 no.1
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• pp.1-17
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• 1995

The success of cell manufacturing applications in FMS rests on the effective cell formation to maintain the independent relations both between machine cells and between part families. This paper presents an integrated method for concurrent formation of cells and families with no E.E (Exceptional Element) in FMS with alternative routings. To determine the maximum number of cell and family with no E.E, mathematical conditions and properties are derived. New concept of nonsimilarity is introduced for each machine and part based on machine-operation incidence matrix and part-operation incidence matrix. To concurrently form the cells and families, integer programming based mathematical models are developed. For the predetermined number of cell or family, model I is used to identify whether E.E exists or not. Model II forms cells and families considering only nonsimilarity. But model III can consider nonsimilarity and processing times. The proposed method is tested and proved by using numerical examples.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.3
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• pp.99-111
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• 1997

We consider a production system with post-operation and early set-up. As soon as there are no more units(raw materials) to process and the machine becomes idle, it undergoes a post-operation. After the post operation, if the number of waiting units is greater than or equal to m, it begins a set-up. After the set-up, if the number of units is greater than or equal to N($\geq$m), it begins to process the units. We first analyze the system by employing the decomposition property of the vacation queue. We, then, propose an algorithm that finds the optimal threshold values ($m^*$, $N^*$). Finally we present some numerical examples and interprete the system behavior.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2072-2075
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• 2003

This paper is studied the high speed processing moving picture encodec to compress and encode a moving picture by real time. This is used the new motion vector search algorithm with smallest search point in H.263 encodec, and is applied the integer DCT for the encodec by converting a moving picture. The integer DCT behaves DCT by the addition operation of the integer using WHT and a integer lifting than conventional DCT that needs the multiplication operation of a floating point number. Therefore, the integer DCT can reduce the operation amount than basis DCT with having an equal PSNR because the multiplication operation of a floating point number does not need.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.221-225
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• 2015

To hoist construction workers to their working space is directly related to the productivity of building construction since hoisting tasks are carried out during the working time. In order to reduce hoisting time in the condition that the number of construction lift-cars is limited, various types of the lift-cars group operation plans such as zoning and sky-lobby have been applied. However, previous researches on them cannot be compared in the performance due to their methodological limitation, discrete-event simulation methods, and cannot be find better solution to increase the performance. Therefore, this research proposed the simulation-based optimization model combining the agent-based simulation method to the scatter search optimization methods. Using the proposed model, this paper carried out the comparison analysis on the performance of typical operation plans and also optimize an operation plans by controlling the service range of lift-cars, the size and number of service zones. In this case study, it is verified that better alternatives than typical operation plans can be exists and it is possible to increase the productivity of building construction.

• Bulletin of the Korean Mathematical Society
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• v.36 no.4
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• pp.661-669
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• 1999

L. Degui introduced an upper bound of Reidemeister number. In this paper we give a simple proof of Degui's Theorem.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2126-2135
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• 1992

In order to prevent the decay heat removal system from failure due to air entrainment or free surface vortex in the piping system, a set of simulating experiments for the midloop operation of nuclear power plant was performed. Through these experiments, a relation between the dimensionless numbers, such as submergence H/d, froude number, reynolds number, was found. However, the effect of reynolds number was negligible for the operation conditions of Nuclear power plant. It was also found that the perturbation of the system by the disturbance such as pump start, valve operation, etc., has a strong effect on the free surface vortex. Furthermore, from a view point of reactor safery, a modified inlet device of reducer type is strongly recommendable for the prevention of air entrainment.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.1
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• pp.85-99
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• 1984

The stability of the two-phase flow in a heated channel is of great importance in the design and operation of the boilers and light water nuclear reactors, because it can cause flow oscillations and lead to a violation of thermal limits with resultant overheating of the channels and cladding. This paper presents a systematic evaluation to the variation effects of the basic four (4) dimensionless parameters in a homogeneous equilibrium model. The flow stability is examined on the ground of static characteristic curves. The complicated transfer function of flow dynamics which gives consideration to the transport lag of density wave is derived, and the transient flow stability is analysed by applying the Nyquist stability criterion in control engineering. The analysis results summed up as follows 1. The coolant flow becomes stable in large friction number and specific flow, while it is unstabale in small friction number and flow. 2. Large phase-change number and Froude number destabilize the two-phase flow, but small numbers stabilize it. The effect to variation of phase-change number is more dominant compared with Froude number. 3. The dynamic analysis is required to hold the sufficient safety of heated channels since only static results does not keep it. The special attention could be payed in the design and operation of heat engines, because the unstaable region exists within the stable boundary at small and middle phase-change number and Froude number.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.468-476
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• 2001

The ROK TRANSCOM is trying to establish a concrete wartime sealift operation plan. But there are many problems to be solved for setting up the plan. The most serious problem is to procure war materiel to be shipped in U.S.A and next one is to determine the number of sealift assets and to allocate them. The process of sealift operation can be described as follows. Before the order of vessel mobilization, all vessels appointed for activation would be scattered in worldwide in the state of Beaded or unloaded. After the order of vessel mobilization, vessels would go to SPGE(seaport of embarkation) to load war materiel. Some loaded ships should offload the commercial cargo to the near port as soon as they are activated, before they would go to SPOE. All vessels would load procured materiel in SPOE and then go to SPOD(seaport of debarkation). They would offload war materiel in SPOD and then go back to SPOE to load war materiel again. We will simulate this process using ARENA(1), evaluate the sealift capability of ROK and find omit problems of the sealift plan. This model ultimately evaluates the sealift capability and provides planners with critical information far establishing and correcting the plan. This study can also provide military planners with a flexible and accessible decision support tool to provide advance planning under a variety of conditions on the sealift capability. The military planner is expected to make use of this model as a standard for establishing effective and concrete sealift operation in the near future. We can conclude how procurement capability significantly affects the result of sealift operation through this model. We could decide the appropriate levee of sealift asset such as the number of vessels and the number of available berth. So we could allocate effectively the resources for completing the sealift operation within the TGT(Target) time.

• Journal of the Chungcheong Mathematical Society
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• v.19 no.4
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• pp.349-356
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• 2006

The aim of this paper is to endow a monoid structure on the set S of all oriented knots(links) under the operation ${\biguplus}$, called addition of knots. Moreover, we prove that there exists a homomorphism of monoids between ($S_d,\;{\biguplus}$) to (N, +), where $S_d$ is a subset of S with an extra condition and N is the monoid of non negative integers under usual addition.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.249-252
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• 2001

A large number of soft switching topologies included a resonant circuit have been proposed. But these circuits increase number of switch in circuit and complicate sequence of switching operation. In this Paper, the authors propose power conversion system, DC-AC inverter of high efficiency and high power factor with soft switching mode by partial resonant method. The result is that the switching loss is very low and the efficiency of system is high. And the snubber condenser used in partial resonant circuit makes charging energy regenerated at input power source for resonant operation.