• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.11
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• pp.1946-1958
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• 2011

Wireless Sensor Network (WSN) is made up of a number of sensor nodes and base stations. Traffic flow in WSN appears self-similar due to its data delivery process, and this impacts queue length greatly and makes queuing delay worse. Active queue management can be designed to improve QoS performance for WSN. In this paper, we propose self-similar traffic rate estimating algorithm named Power-Law Moving Averaging (PLMA) to regulate packet marking probability. This algorithm improves the availability of the rate estimation algorithm under the self-similar traffic condition. Then, we propose an adaptive Proportional Integral algorithm (SSPI) based on the estimation of the Self-Similar traffic rate by PLMA. Simulation results show that SSPI can achieve lower queue length jitter and smaller setting time than PI.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.4
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• pp.153-165
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• 2014

We present a new framework for rental capacity management in which rental capacity is dynamically managed by means of temporary inventory addition/return. While serving customers with its own (native) capacity, the rental firm rents additional rental capacity from an upper echelon rental company so that it can avoid lost sales which may occur when stock is not sufficient, and returns it when stock becomes sufficiently large enough to cope with demands. Formulating the model as a Markov decision process, we investigate a flexible capacity addition/return policy that maximizes the firm's profit with respect to system costs. Numerical study indicates that rental operation with capacity addition/return can be economically favorable over rental operation without capacity expansion/return and can contribute the reduction in the size of native rental capacity.

• 한국디지털정책학회:학술대회논문집
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• 2004.05a
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• pp.525-544
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• 2004

The Purpose of this study is to examine logistics characteristics related to electronic commerce and to suggest improvement of logistics Service in electronic commerce. This paper concerns the logistics functions which are essential for completing a commerce process even under the EC environment and provides ways to improve the logistics performance. Electronic commerce have introduced two scenes; dramatic change of the existing distribution surroundings and noticeable achievement of the economic advance and social efficiency. But, in the same scene, electronic commerce can be a threat to business condition, especially logistics management. It suggests that for activation of EC it is necessary to strengthen the strategic alliances, introduce GPS and use the third party logistics positively to prepare for the settlements of traffic problems, support the introduction of integrated logistics service and logistics information system.

• Journal of Korean Society for Quality Management
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• v.36 no.4
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• pp.19-28
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• 2008

The purpose of this study is to search for the quality characteristics for evaluation of the information system. The quality characteristics are an important factor for selection, implementation and maintenance of the information system of the company. Of course in the end, the quality of the information system in a company is directly related with the business performance of the company. This paper is a study of a model with four independent variables, a parameter variable, and a total of 15 hypotheses, investigated by a questionnaire method. It conducted the model analysis of structural equation to use statistical package for questionnaire analysis.

• Journal of the Korean Institute of Rural Architecture
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• v.7 no.1
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• pp.39-50
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• 2005

This study is result of interview and investigation into three rural communities progressing Rural activity, and points to be considered before promoting policy 1) Resident participation taking a lot of time, need to sustainable education and chance of personal experience, as well as stage of working plan and performance must be a serious consideration about resident opinions. 2) Until placing operation and management on the right track, experts and administrators will be help aspects of software and finance. 3) It is necessary to periodically train rural activity experts, and educate business persons. 4) Through checking a process, each community improve, supplement, will work out the next support system.

• Information Systems Review
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• v.7 no.1
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• pp.241-256
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• 2005

This study first identifies the critical factors for the successful e-government implementation. Then, it examines how these factors are emphasized and recognized during our e-government implementation process. Finally, it analyzes the relationship between the critical factors and the e-government performance and provides the way in which our e-government is successfully developed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.466-482
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• 2015

IT is the key enabler of digital economy. Appropriate usage of IT can provide a strategic competitive advantage to a firm in a dynamic competitive environment. However, there has been a continuing debate on whether IT can actually enhance the productivity of firms. This concept is called IT productivity paradox. In this study, we analyzed the causality among appropriate indicators to demonstrate the real impact of IT on productivity. The 12,100 sample data from 2011 were used for analysis. As expected, the results indicated that mobile device usage, website adoption, e-commerce, open source, cloud computing, and green computing positively influence IT productivity. This unprecedented large-scale analysis can provide clarification regarding the ambiguous causal mechanism between IT usage and productivity.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.4
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• pp.398-407
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• 2008

We consider a product recovery system that a single product is stocked in order to meet a demand from customers who may return products after usage. This paper addresses a problem of when to release a procurement process to replenish serviceable inventory and how many new products to procure. The structure of the optimal procurement policy is examined and numerically identified as a monotonic threshold curve. A numerical procedure is presented to jointly find the optimal procurement order size, optimal procurement policy, and optimal discounted profit. Sensitivity analysis also indicates that these optimal performance measurements have monotonic properties with respect to system parameters.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.156-161
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• 2004

The application of solar energy, in the field of alternative energy, was on the increase tendency. In the case of advanced nations, through continuous R&D, solar hot water heater with high efficiency has been used for the house and the industrial process on business, advanced nations were reached up the experimental stage of solar generation system. But, the actual circumstance of the domestic has been not accomplished the popularization of solar hot water heater and the settlement of it which is the fundamental stage of the solar energy usage. This trouble, the domestic was flooded with small enterprise for producing solar hot water heater, was caused by the popularization and the production without verification of performance. To supply the monitoring program for evaluating solar hot water heater, this research was purpose to improve the technical development of the enterprise for producing solar-heat hot-water-boiler and served as an aid for the enlargement and the popularization on solar energy.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.768-775
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• 2010

Automotive industry is a major business area in this country and it becomes more and more important. In order to maintain high quality of vehicles, every parts should be inspected. Among them the inspection job of the knuckle bracket holes of the outer tube of shock-absorber has been done manually until now. So, it takes long time and every product can not be inspected. An automatized inspection system was proposed utilizing machine vision technology, which was composed of a slit beam laser, CCD camera, image processing computer, special jig and illuminating back lights. An algorithm which could process images of the laser and bracket holes, then gave the position, radius, roundness of the holes, was developed. This system was applied for the good and no good products and the performance was confirmed.