• Journal of Information Technology Applications and Management
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• v.24 no.2
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• pp.81-96
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• 2017

Forecasting long-term mobile service demand is inevitable to establish an effective frequency management policy despite the lack of reliability of forecast results. The statistical forecasting method has limitations in analyzing how the forecasting result changes when the scenario for various drivers such as consumer usage pattern or market structure for mobile communication service is changed. In this study, we propose a dynamic model of the mobile communication service market using system dynamics technique and forecast the future demand for long-term mobile communication subscriber based on the dynamic model, and also experiment on the change pattern of subscriber demand under various scenarios.

• Journal of the Korean housing association
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• v.12 no.3
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• pp.1-12
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• 2001

The purpose of this study was to investigate the outdoor space of the recent built apartment complex in Ulsan and to provide the basic information for planning and apartment outdoor space. Multiple methods were utilized such as questionnaire, observation, behavior-mapping, and photography. The sample consisted of 382 residents living in four apartment complex in Ulsan. data were analyzed by frequency and percentage using SPSS PC+. The observation was performed in seven outdoor space, i.e., green area, road area, exercise area, play area, parking area, and approach area. According to the findings of this study, residents did not actively involve in outdoor activities and seldom use the outdoor space. Various changes and erosions were observed as a trace, especially near fence and grass area because of unplanned location of entrances. Finally this study suggested several planning guidelines for outdoor space in apartment complex.

• Journal of the Korean Home Economics Association
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• v.38 no.12
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• pp.101-110
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• 2000

The purpose of this study were to investigate the influences of fashion leadership on consumers'evaluation of domestic and imported perfume product, and perfume purchasing behaviors and to find out the demographics and consumer value on fashion leadership. The data were collected from 369 female college students using questionnaire. The results were as follows: First, there were significant differences on consumers'evaluation of domestic and imported perfume product between the groups on fashion leadership. The higher the fashion leadership, the much positive consumers'evaluation of imported perfume product. Second, Fashion leaders'the frequency of perfume usage and the pieces of perfume product were higher than fashion followers. The most important perfume attribute of all groups was scent, and fashion leader took the much significant view of brand name than fashion followers. Third, Fashion leaders'economical level and pleasure oriented value was higher than fashion followers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.912-917
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• 2004

The increase of illegal usage and conflict in digital content market would diminish motivation of creators for their work, furthermore break down digital content market on cyber-space. Watermarking technology support to the legal users by the protection technique based on the digital content copyright protection method(DRM). Most of previous digital watermarking have embeded to the content. In this paper, we propose a wavelet based watermarking method which is used for implementing in the frequency domain.

• Journal of the Korean Institute of Educational Facilities
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• v.21 no.6
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• pp.25-32
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• 2014

Korean academic libraries are facing serious space shortage problems due to an inability to accommodate for the rapidly increasing number of printed materials. Despite the current situation, Korean academic libraries have largely focused on impractical applications of the new library paradigm, using technology or management programs to improve the quality of research and learning environments of the university. However, such improvements would be fruitless without first resolving the space shortage crisis. In order to make realistic improvements to the quality of academic libraries, this study used questionnaires to employ the opinions of librarians currently practicing at such Korean libraries. Survey questionnaires about types and causes of space shortage problems, library facility expansion plans, expected effects of expansion, frequency of and reasons for furniture relocation, and tight spaces needing improvement were distributed to selected 4-year college librarians through Google Drive. Analysis of survey responses indicated that library space shortage was largely responsible for the hindrance of research and learning environments. Furthermore, it reflected the urgency to secure book storage space.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.4
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• pp.282-290
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• 2000

In this paper, the charge control with the input voltage feedback is proposed for the input series-output series-output parallel connected converter configuration for the high speed train power system application. This control scheme accomplishes the output current sharing for the output-parallel connected modules as well as the input voltage sharing for the input series connected modules for all operating conditions including the transients. It also offers the robustness for the input voltage sharing control according to the component value mismatches among the modules. And this configuration enables the usage of MOSFET for a high voltage system allowing a higher switching frequency for lighter system weight and smaller size. The performance of the proposed scheme is verified through the experimental results.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.462-465
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• 2009

This study described the design and construction of uninterruptible power supply(UPS) system for supercomputering system. KISTI's supercomputer system is served for all 24 hours, and power be achieved in stable voltage and frequency range. We analyzed the electric power usage for 4 years, and we considered cost and stability and we contructed UPS for supercomputer system.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1477-1479
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• 2005

In this paper, we proposed the electric circuit using one common arm of H-Bridge inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and Transformers. and furthermore we suggested the new multi-level PWM inverter using PWM level to reduce THD(Total Harmonic Distortion) and we used the switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype 15-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.

• Asia pacific journal of information systems
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• v.1 no.1
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• pp.5-16
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• 1991

Business firms have been expressing a strong interest in an effective structure of computing resources. In this respect previous studies provide some guidelines about the deployment of hardware, but the question of which information systems (IS) would be run under the dispersed hardware is still unanswered. The main purpose of the study is to analyze the relationship between various IS characteristics and the distribution of IS. The IS characteristics studied in this research include the usage frequency of IS in a dispersed plant, the currency of information required by the headquarter, the data volume processed in the plant, the relatedness of IS with other information systems in the plant. The survey was performed over the domestic, large manufacturing firms. The most noticeable finding is that the more the updated information is required in the headquarter, or the more related IS is to other information systems in the plant, the more IS is distributed.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.506-515
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• 2008

Recently, it is exceedingly required to produce metal powders with tailored shape and phase altogether in order to fabricate high performance functional parts such as magnetic core or electro-magnetic noise suppressor for high frequency usage. Therefore, the collision phenomena of in-flight droplets against chamber wall or neighboring in-flight droplets each other is investigated by a computational method in order to get useful information about how to design the atomizing system and how to tailor process parameters not to make irregular-shaped powders during gas atomization process. As a results, smaller powders, lower melt temperature are known to be favorable for droplets not to collide against chamber wall. In additions, powders of narrower size distribution range, lower droplet generation rate, lower melt temperature, lower gas velocity are desirable to prevent droplet-collisions against neighboring in-flight droplets.