• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.11
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• pp.2956-2979
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• 2012

Along with the development of Information Technology, online transactions through Internet have become more popular for the reasons of convenience and efficiency. In order to provide secure and reliable online transactions, an effective electronic payment protocol is crucial. In this paper, we propose a novel electronic payment protocol for digital product transactions with an offline arbiter to achieve fair exchange, automated dispute resolution, customer anonymity, and customer unlinkability. In our protocol a product token is adopted to eliminate the need of key management for digital product decryption in the offline arbiter. In addition, Elliptic Curve Cryptography (ECC)-based self-certified public key is utilized to further reduce computing overheads. According to our analysis, the efficiency of our protocol can be greatly increased in comparison with previous literatures.

• Journal of Korea Multimedia Society
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• v.10 no.6
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• pp.699-706
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• 2007

This article is an approach to improving the clustering of Web images by using high-level semantic features from text information relevant to Web images as well as low-level visual features of image itself. These high-level text features can be obtained from image URLs and file names, page titles, hyperlinks, and surrounding text. As a clustering algorithm, a self-organizing map (SOM) proposed by Kohonen is used. To evaluate the clustering efficiencies of SOMs, we propose a simple but effective measure indicating the accumulativeness of same class images and the perplexities of class distributions. Our approach is to advance the existing measures through defining and using new measures accumulativeness on the most superior clustering node and concentricity to evaluate clustering efficiencies of SOMs. The experimental results show that the high-level text features are more useful in SOM-based Web image clustering.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1813-1818
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• 2006

We demonstrate a new approach to form gradient hole injection layer (HIL) in organic light-emitting diodes (OLEDs). Single spincoating of hole-injecting conducting polymer compositions with a perfluorinated ionomer results in gradient workfunction through the layer by self-organization, which lead to remarkably efficient single layer polymer light-emitting diodes (PLEDs) (${\sim}21$ cd/A). The device lifetime was significantly improved (${\sim50$ times) compared with the conventional hole injection layer, poly(3,4-ethylenedioxy-thiophene)/polystyrene sulfonate. This solution processed HIL also produced dramatically enhanced luminous efficiency (${\sim}34$ cd/A) in vacuum- deposited green fluorescent OLEDs while the vacuum deposited HIL gave the luminous efficiency of ${\sim}23$ cd/A in the same device structure.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1973-1976
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• 1998

Recently, new trend in telecommunication device is to apply low voltage, about 3.3V-1.5V. However, it is undesirable in view of high efficiency and power desity which is the most important requirement in the distributed power system. Rectification loss in the output stage, in on-board converter for distributed power system are constrained to obtain high efficience at low output voltage power suppies. This paper explains the basic operational principles of three kinds of ZVS DC/DC converters with self-driven synchronous rectifier. The three topologies are analyzed by simulation and exprimentation, and the characteristics comparisons of high efficience converter are carried out in view of the minimized rectification losses in the out stage.

• The Journal of Information Systems
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• v.12 no.1
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• pp.47-66
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• 2003

This study was examined the relationship between the exogenous and endogenous variables in our model to measure ERP system performance using path analysis. The exogenous variables are system quality, user participation, user training, top management support and self-efficacy, and the endogenous variables are system usage, user satisfaction, and work efficiency. The results of the study are shown as follows. First, all the exogenous variables in our model have a direct effect on user satisfaction, and system quality, training, and self-efficacy have a direct effect on system usage. Second, system usage has a direct effect on user satisfaction and user satisfaction has a direct effect on work efficiency. The findings show that the exogenous variables in the model are important to increase ERP implementation success.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2126-2130
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• 2008

Gasoline engine have proved its utility in light, medium and heavy duty vehicle in every sector of the world community. The concern about long term availability of petroleum and the increasing threat for the environment by the increasing load of vehicular emission, compel the technology to upgrade itself for meeting the challenges. CNG is environmentally clean alternative to the existing SI Engines with out much change in the hardware. Many researchers have found this as a potential substitute to meet the energy requirement. Higher octane number and higher self ignition temperature make it a good gaseous fuel. Although power output is slightly lesser than the gasoline it's thermal efficiency is better than the gasoline for the same SI Engine. Results showed that reduced CO, hydrocarbon emissions is a favorable outcome, with slight increase in $NO_x$ emission when compared with gasoline fuel to dual fuel mode in the existing SI Engines.

• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.39-45
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• 2019

The aim of this research is to find out how convergent operation of the learning coaching and compensation system affects the academic self-efficiency and learning performance of university students. In the second semester, a compensation system was prepared based on learning coaching and learning outcomes, made a notice in advance, and conducted a survey before and after operation to measure the academic self-efficacy. In addition, the MLST-II Learning Strategy Diagnosis Examination was conducted on G university students to diagnose the learning tendency. As a result, although G University students felt a reluctance by coaching the learning community and expected negative results during the course of participation in the learning community due to low motivation and low expectation of results, they showed a significant improvement in academic self-efficiency and learning outcomes. Therefore, even students with negative learning tendency will need to consider how to operate these programs in the educational field, as the expert's learning coaching and compensation systems produce positive results for students' academic self-efficiency and learning outcomes rather than leaving them to autonomy.

• Journal of Digital Contents Society
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• v.15 no.2
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• pp.191-196
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• 2014

In this study, new self-initiated peer tutoring is suggested to computer graphic's subject. Subject of computer graphics is practice based subject, therefore learning efficiency and learning level of students is different from each other. To improve the learning efficiency and enhance the interest of related subject, new peer tutoring activities was performed with main class in 6 months (including vacation). We analyzed the results of tutoring activities and conducted survey tutees. Results of the analysis and the survey were shown that students (tutees) are satisfied with and interested in the class of computer graphics.

• Management & Information Systems Review
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• v.8
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• pp.61-86
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• 2002

This study is focused on how to effectively support Busan regional footwear companies in partnership with parent company, in particular how to lead a mutual supplementary relationship with the minor firms while improving the efficiency in strategic outsourcing. Recently, The Korean Footwear Industries and companies are making a lot of efforts to enhance the structure of high expenditure and low efficiency as a means of recovering their competitiveness. As a domestic companies have a tendency to almost all the tasks on bloc, it is true that their competitiveness is on the rapid decline for they prefer self-reliance on the premise that all the production should be dealt with for themselves. It is strategic outsourcing that is taken into account as a strategic vehicle for converting such self-reliance into the system of low expenditure and high efficiency. This study also conducted questionnaire researches, designed to find out the difference between the parent company and minor firms in the recognition and contentment on the purchasing and supplying activities. The result of the questionnaire researches went through further analysis and study to give a reasonable alternatives.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.133-140
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• 2007

DCM (Deep Cement Mixing Method) has been applied to build structures such as self-supported earth retaining walls. DCM columns should be penetrability into the stiff layer to assure the self-supporting ability. On the penetration increase of blade attached to the DCM mixing tools, a spiral mixing blade has been revised. Penetration characteristics of spiral blades in the stiff soil layer were evaluated through Gimhae and Incheon areas. The spiral mixing blades could penetrate into the stiff soil layers which have the N-value of greater than 30 although the penetration rate is somewhat slow. Penetration characteristics and economical efficiency should be discussed to determine the critical depth of the spiral mixing blade because the penetration efficiency can decrease in the stiff layer in this paper.