• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.1
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• pp.51-57
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• 2010

This paper presents temperature control of engine cooling system using a controllable magnetorheological(MR) fan clutch. An appropriate size of MR fan clutch is devised and modeled on the basis of Bingham model. Subsequently, an optimization to determine design parameters such as width of housing is undertaken by choosing the reciprocal of the controllable torque as an objective function. Under consideration of spatial limitation, design parameters are optimally determined using finite element analysis. A sliding mode controller is then designed to control the angular velocity of the MR fan clutch using experimentally determined parameters. The designed controller is experimentally implemented and control performances of the MR fan clutch system are evaluated.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.1989-1995
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• 2009

Efficient one-pot synthesis of arylmethylene bis(3-hydroxy-2-cyclohexene-1-ones) and xanthenediones by EDDA and In($OTf)_3$-catalyzed reactions was developed starting from dimedone and aryl aldehydes. The key strategies of these reactions involve domino Knoevenagel/Michael reaction or Koevenagel/Michael/Cyclodehydration reactions. The scope and limitation of the two catalysts under various reaction conditions were investigated and described.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.3
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• pp.137-146
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• 2007

CFD simulation is a very useful tool to predict the concentration of contaminant generated from the building materials in a single room. However, there is a limitation on analyzing air movement and contaminant concentration in a multi-room when the door of each room is closed. In this study, network based simulation was coupled with contaminant simulation for the multi-room condition, using an network simulation tool 'ESP-r'. The coupled simulation was first validated with experimental measurements which performed to define the characteristics of the analyzed space prior to the simulation, and indoor air flow and contaminant concentration between rooms were then analyzed when the door of each room was open and closed in the case of natural and forced ventilation.

• The Journal of Information Systems
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• v.16 no.1
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• pp.23-45
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• 2007

Today, most companies are building up and using online communities on their websites. But there are few studies on forming and operating online communities. This study shows the influence of social presence on these factors like usefulness, ease of use, playfulness, satisfaction community trust, and its ultimate contribution to community flow. An Empirical results suggest as follows. (1) social presence has stronger effect on usefulness, ease of use, playfulness, (2) usefulness and playfulness has a positive influence on satisfaction, (3) ease of use doesn't have a significant impact on flow, (4) satisfaction is positively influences on community trust and flow, (5) community trust influences on flow. It is necessary to succeed with next studies following this one about online community in spite of its limitation. Finally, we present contribution and propose future research directions.

• 한국디지털정책학회:학술대회논문집
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• 2004.11a
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• pp.211-219
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• 2004

Due to rapid increases in Internet users, it becomes essential to provide well-established web services and monitor web server's load for the sake of reliable web server management. The existing web server load monitoring has been based on such cable methods as RPC, RMI, CORBA and etc. But it has the limitation in bringing information both anywhere and anytime over the Internet. This thesis is aimed to realize real-time wireless web server monitoring system based on Wireless Application Protocol (WAP). As any user can log on wirelessly to the Internet at any time through wireless terminals like PDA, the realization will make possible instant and real-time web server monitoring.

• 한국디지털정책학회:학술대회논문집
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• 2004.11a
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• pp.283-294
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• 2004

Within the rapidly changing environment of global economics, the environment of higher education in the universities & companies, also, has been, encountering various changes. Popularization on higher education related to lifetime education system, putting emphasis on the productivity of education services and the acquisition of competitiveness through the market of open education, the breakdown of the ivory tower and the Multiversitization of universities & companies, importance of obtaining information in the universities & companies, and cooperation between domestic and oversea universities, industry and educational system must be acquired. Therefore, in order to adequately cope with these kinds of rapid changes in the education environment, operating E-Learning Education & company by utilizing various information technologies and its fixations such as Internet, E-mail. CD-ROMs. Interactive Video Networks (Video Conferencing, Video on Demand), CableTV etc., which has no time or location limitation, is needed.

• Journal of Korean Institute of Industrial Engineers
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• v.3 no.2
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• pp.41-55
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• 1977

The physical distribution system is composed of all the activities associated with getting products from the factory to the consumer through the firm's channels of distribution. An increasing amount of attention has been recently devoted to the component problems associated with distribution system analysis. This paper analyzes effect of system parameters which are safety factor of depot's stock, limitation of direct supply from shop stock to customer and ordering quantity on the physical distribution cost and the evaluated items by the Simulation. The distribution system simulator views system as being composed of three structural entities, presents a case study of a Chemical manufactures and carried on one year computer running.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.3
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• pp.31-42
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• 1988

This paper describes a computer aided process planning system called "Deep-Drawing", "Deep-Drawing" is designed for the drawing sequence of cylindrical and rectangular cups with or without taper and flange. The computer program has written in BASIC language with personal computer. Design Rules for process planning are formulated from process limitation, plasticity theory and experimental results including the know-how of many manufacturing factories. "Deep-Drawing" Capabilities include the analysis of drawing sequence by the determination of optimal drawing ratio, the determination of intermediate shape, dimensions, punch and die radius etc., the calculation of drawing loads and blank holder force to perform each drawing step, and the graphic outputs for the operation sheet.tputs for the operation sheet.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.115-118
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• 1990

Recently, it has been reported that the Insulating films deposited by PECVD show some degradation under somewhat high electric field. In this paper, we Introduce silicon nitride films deposited by LCVD, and evaluate the breakdown and wear-out of these films by TDDB test. Further, failure times against electric field are examined and acceleration factors $\gamma$ are obtained for each case. As a result, it is shown that the breakdown and wear-out limitation for these films is improved.

• Korea-Australia Rheology Journal
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• v.15 no.4
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• pp.167-171
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• 2003

The backlight unit (BLU) is used as a light source of TFT liquid-crystalline-display (TFT-LCD) module. In this backlight unit, one of important components is the light guide, which is usually made of transparent polymers. Currently, the screen-printing method is mainly used for the light guide as a manufacturing process. However, it has limitation to the flexibility of three-dimensional optical design. In the present paper a new alternative manufacturing method for the light guide with low-cost is proposed. This manufacturing method is named as direct surface forming (DSF), which is very similar to the well-known hot embossing except for partial contact between mold and substrate. The results of this new manufacturing method are presented in terms of processing condition, dimensional accuracy, productivity, etc.