• Journal of Engineering Education Research
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• v.2 no.1
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• pp.29-38
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• 1999

DEA (Data Envelopment Analysis) is applied to evaluate performance of 14 academic departments at the college of engineering in Yonsei University. Various input and output variables are used to identify operational inefficiency and to suggest some strategic improvement. Additionally, we analyze organizational changes of some existing departments to be merged under several scenarios. Our study results are expected to effectively provide constructive directions for reconfiguration of academic departments.

• Korean Management Science Review
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• v.15 no.2
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• pp.45-58
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• 1998

Enterprise resource planning(ERP) in nature entails large scale business process redesigns and the corresponding risks. To reduce such risks, enterprise modeling(EM) approach could be adopted through which ERP is planned and effectively implemented on a consistent basis throughout the entire organization. The scope of this paper is to report on EM experiences and lessons learned in the process of ERP implementation. Through a case study, this paper presents and EM methodology which takes due account of strategic business processes, information flows, organizational requirements, and their interdependencies. To assess the impact of distributed application scenarios on effective ERP implementation, alternative EMs have been created and evaluated whether they support information requirements for strategic decisions and day-to-day operational activities, core business processes, and business functions as required. Practical issues and problems raised in the EM process have been discussed.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.2
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• pp.75-86
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• 2008

A remarshalling is one of the operational strategies considered importantly at a port container terminal for the fast ship operations and heighten efficiency of slacking yard. The remarshalling rearranges the containers scattered at a yard block in order to reduce the transfer time and the rehandling time of container handling equipments. This Paper deals with the rearrangement problem, which decides to where containers are transported considering time value of each operations. We propose the mixed integer programming model minimizing the weighted total operation cost. This model is a NP-hard problem. Therefore we develope the heuristic algorithm for rearrangement problem to real world adaption. We compare the heuristic algorithm with the optimum model in terms of the computation times and total cost. For the sensitivity analysis of configuration of storage and cost weight, a variety of scenarios are experimented.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.515-518
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• 2003

Mathematical models can be used to evaluate the effects of operational alternatives of dam on the downstream aquatic environment. An unsteady, one-dimensional water quality model, CE-QUAL-RIVI was calibrated and validated in Geum river as a sub model for the realtime water management system in the basin. The main usage of the model within the system is to predict the effects of flow regulation by Daecheong Dam on the downstream water quality. The validated model was then used to simulate dynamic water quality changes at several key stations responding to different scenarios of reservoir releases under a hypothetical spill condition. The model showed fairly good performance in the simulation of hydrodynamic and mass transport processes under highly unsteady conditions.

• Journal of Communications and Networks
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• v.8 no.4
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• pp.442-450
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• 2006

Inter-operability between heterogeneous radio access technologies (RATs), in the sense of seamless vertical han-dover (VHO) support with common radio resource management (CRRM) functionalities, has recently attracted a significant research attention and has become a prominent issue in standardization fora. In this paper, we formulate the problem of load balancing between cooperative RAT's as a mathematical program and by trading off a pre-defined delay tolerance per request we propose a vertical handover batch processing (VHBP) scheme. To quantify the performance of the proposed VHBP scheme we compare it with a baseline processing scheme, where each VHO request is processed independently under a number of different network scenarios. Numerical investigations reveal significant net benefits of the proposed scheme compared with the baseline, both in terms of achieved load balancing levels but also with regard to the acceptance rate of the VHO requests.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2266-2284
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• 2012

Recent studies have indicated that a significant improvement in wireless video throughput can be achieved by Cross Layer Design with Side-information (CLDS) protocols. In this paper, we derive the operational rate of a CLDS protocol operating over a realistic wireless channel. Then, a Rate-Distortion (R-D) empirical model for above-capacity Scalable Video Coding (SVC) is deduced to estimate the loss of video quality incurred under inaccurate rate estimation scenarios. Finally, we develop a novel Unequal Error Protection (UEP) scheme which leverages the characteristics of LDPC codes to reduce the distortion of video quality in case of typically-observed burst wireless errors. The efficacy of the proposed rate adaptation architecture over conventional protocols is demonstrated by realistic video simulations using actual IEEE 802.11b wireless traces.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2136-2152
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• 2012

The growth of Internet technologies and the widespread use of mobile devices have been paving the way for the increasing use of conferencing services. Two types of systems have been designed to provide conferencing services: 1) a conferencing system using session control over a peer-to-peer (P2P) network and 2) an IP Multimedia Subsystem (IMS) conferencing system. The IMS conferencing system was developed to adapt to a server-based centralized system, whereas the benefits of the P2P operational model in providing such conference services are widely acknowledged. However, each system provides conferencing services only to its own users. Therefore, in this paper, we propose an interworking model to support multimedia conferencing service between the P2P environment and IMS networks. We also introduce protocol architecture and some service scenarios. To verify this system model and the design architecture, we perform an actual implementation and show experienced test results.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.3
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• pp.266-273
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• 2011

This paper deals with missile autopilot design for agile turn phase in air-to-air engagement scenarios. To attain a fast response, angle-of-attack (AOA) is adopted for an autopilot command structure. Since a high operational AOA is generally required during the agile turn phase, dealing with the aerodynamic uncertainties can be a challenge for autopilot design. As a remedy, a new controller design method based on robust nonlinear control methodology such as time delay control is proposed in this paper. Nonlinear observer is also proposed to estimate the AOA in the presence of the model uncertainties. The performance of the proposed controller with variation of the aerodynamic coefficients is investigated through numerical simulations.

• ETRI Journal
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• v.33 no.3
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• pp.299-309
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• 2011

Energy consumption is a key issue in body sensor networks (BSNs) since energy-constrained sensors monitor the vital signs of human beings in healthcare applications. In this paper, packet size optimization for BSNs has been analyzed to improve the efficiency of energy consumption. Existing studies on packet size optimization in wireless sensor networks cannot be applied to BSNs because the different operational characteristics of nodes and the channel effects of in-body and on-body propagation cannot be captured. In this paper, automatic repeat request (ARQ), forward error correction (FEC) block codes, and FEC convolutional codes have been analyzed regarding their energy efficiency. The hop-length extension technique has been applied to improve this metric with FEC block codes. The theoretical analysis and the numerical evaluations reveal that exploiting FEC schemes improves the energy efficiency, increases the optimal payload packet size, and extends the hop length for all scenarios for in-body and on-body propagation.

• Spatial Information Research
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• v.10 no.4
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• pp.515-532
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• 2002

Planning Support System (PSS), an alternative framework of computer-aided planning system combining geographic information system (GIS), urban models, and visualization tools, has been actively researched and applied in many developed countries. This paper introduces a PSS-based land use change model, What if\ulcorner PSS, by applying it to Chongju City, Korea. This model application study used the spatial database, Restricted Development Zone (RDZ), and other hypothetical land supply- and demand-related policies of Chongju City. The collaborative PSS model supported land use planning process by helping users to speedily and easily create and test policy-oriented scenarios. The study found that the fully operational PSS model was readily applicable and useful to Korean local land use planning. The paper discusses the conceptual model framework, data requirement, application process, model output, and practical usage. This study would be considered as a prototypical approach of PSS-based land use plan making for Korean cities.