• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.535-540
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• 2010

We present an optimization model for how to assign the freight trains to transshipment tracks and allocate the containers to the freight trains in a rail container terminal. We formulate this problem as a multi-criteria integer programming to minimize the makespan of job schedule and simultaneously to maximize the loading throughput, i.e. the number of containers to be disposed per day. We also apply our model to the instance obtained from the real-world data of the Uiwang Inner Container Depot. From the experiments, we can see an improvement of approximately 6% in makespan, which means that our model can contribute to the improvement of the disposal capacity of containers without additional expansion of facilities.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.608-616
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• 2007

OFDM Systems for multi-user use adaptive modulation and ending (AMC) which is a method that selects suitable modulation order and code rate depending on channel state of each user. Using AMC, OFDM system can provide high quality and reliable communication. Base station using AMC scheme requires downlink channel information of each terminal to operate optimality. However, under practical system environment, it is unsuitable to transmit all channel information because uplink bandwidth of the system is limited. In this paper, we propose a flexible block-wise loading (FBL) algorithm combined with a novel CQI feedback scheme with reduced number of required bits to optimize the performance of AMC system. Proposed algorithm allocates sub-carrier groups dynamically to improve the sector throughput and outage probability performance.

• Journal of the Korea Society for Simulation
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• v.18 no.2
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• pp.19-27
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• 2009

This paper addresses the berth allocation problem in naval ports. Navy vessels need various services such as emergency repair, missile loading, oil supply and many others while commercial vessels only unload and load container at the port. Furthermore, naval vessels have to shift frequently due to a limited capacity of the port. The objective of this paper is to minimize the total number of nesting vessels at the naval port. In other word, the objective is to maximize the total number of naval battleships engaging in the sea. A mixed integer programming(MIP) model is developed and experiments are conducted with ILOG CPLEX 11.0. We compare the computational results of the MIP model to the current scheduling approach by the ROK Navy. The results showed that MIP model performed well by minimizing the number of nesting vessels. and avoiding unnecessary shifts.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.19-24
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• 2009

When a dynamic method is applied at the time of occurrence of an client's connection request for most of the online gaming server engine, the gaming server is processing a session connection, it's initialization. Yet, such a method will cause a lot of loading and bottle-neck in the gaming server at the same time. Therefore we propose the object polling scheme to minimizes a memory fragmentation and loading of the initialization on the client using a static allocation method for an efficient On-lin gaming serverin this paper. We implement the gaming server applying to our proposed scheme, and we show an improvement in our proposed scheme by performance analysis in this paper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.91-98
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• 2003

In the structural analysis of a launch vehicle, the construction of loading functions and the determination of responses to them are very important. Among many kinds of loads, acoustic load generated by exhaust is a random load that can be described in a statistical manner. In this study, loading functions corresponding to the acoustic loads are constructed and applied to the structural analysis of launch vehicle. Acoustic loading functions are constructed using source allocation method. Structural analyses are carried out by using finite element modelling and frequency response function of finite element model. The stresses resulting from acoustic loads and acceleration power spectral density functions at interfaces of each section are calculated. These analyses are essential for the development of environmental test specifications and associated dynamic design requirements which are necessary to ensure overall vehicle reliability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1483-1490
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• 2009

Orthogonal frequency division multiplexing (OFDM) has been investigated as an enabling technology for future wireless communications such as ad hoc, mesh and sensor networks. However, prior works on bit-loading lack consideration of the constraints on energy and computing facility in sensor networks. In this paper, we suggest an adaptive bit allocation algorithm for a frequency selective fading channel environment which exploits channel state information obtained through a feedback channel. The proposed algorithm significantly reduces computational complexity and satisfies the power budget. Also, its throughput is comparable to the optimum solution. Simulation results support the claim stated.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.3
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• pp.35-49
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• 1993

The node coloring problem is a problem to color the nodes of a graph using the minimum number of colors possible so that any two adjacent nodes are colored differently. This problem, along with the edge coloring problem, has a variety of practical applications particularly in item loading, resource allocation, exam timetabling, and channel assignment. The node coloring problem is an NP-hard problem, and thus many researchers develop a number of heuristic algorithms. In this paper, we survey and classify those heuristics with the emphasis on how an algorithm orders the nodes and colors the nodes using a determined ordering.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.454-459
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• 2003

The process of determining whether, when, where and how to intervene, of deciding on optimum allocation of resources and minimizing the cost is a very complex problem: different track sections tend to behave differently under the effects of loading; decision-making processes for maintenance work are closely interrelated technically and economically; decision-making for maintenance plans is based on a large quantity of technical and economic information, extensive knowledge and above all experience. For that reason, It is considered very important to develope objective and computer-aided decision-making support system for track maintenance plan. On this paper, we reviewed ECOTRACK system and present the plan of develope decision-making support system for track maintenance appropriate to local condition.

• Earthquakes and Structures
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• v.7 no.6
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• pp.1025-1044
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• 2014

In this paper, a systematic technique is proposed for the optimal placement and design of nonlinear dampers for building structures. The concept of Output Frequency Response Function (OFRF) is applied to analytically represent the output frequency response of a building frame where nonlinear viscous dampers are fitted for suppression of vibration during earthquakes. An effective algorithm is derived using the analytical representation to optimally determine the locations and parameters of the nonlinear dampers. Various numerical examples are provided to verify the effectiveness of the optimal designs. A comparison of the vibration suppression performance with that of the frame structure under a random or uniform damping allocation is also made to demonstrate the advantages of the new designs over traditional solutions.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.886-891
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• 2004

The process of determining whether, when, where and how to intervene, of deciding on optimum allocation of resources and minimizing the cost is a very complex problem: different track sections tend to behave differently under the effects of loading; decision-making processes for maintenance work are closely interrelated technically and economically; decision-making for maintenance plans is based on a large quantity of technical and economic information, extensive knowledge and above all experience. For that reason, It is considered very important to develope objective and computer-aided decision-making support system for track maintenance plan. On this paper, we made a survey of the state-of-art of decision-making support systems for track maintenance which were developed and used abroad and reviewed requirements of system and present the plan of develope decision-making support system for track maintenance appropriate to local condition.