• 충청수학회지
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• 제15권2호
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• pp.13-23
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• 2003

We prove a simplicity of the $C^*$-algebra generated by some $C^*$-subalgebra and a Haar unitary in a free product of finite von Neumann algebras. Some examples and questions are given.

• 한국공간구조학회지
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• 제13권3호
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• pp.12-18
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• 2013

• 제어로봇시스템학회논문지
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• 제8권12호
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• pp.1041-1047
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• 2002

It is known that parallel-type mechanisms have many singularities than serial-type mechanisms. In haptic application, these singularities deteriorate the system performance when the haptic system displays the reflecting force. Moreover, different from general manipulators, haptic systems can't avoid the singular point because they are operated by user's random motion command. Although many singularity-free algorithms for serial mechanisms have been proposed and studied. singularity-free algorithms for parallel haptic application have not been deeply discussed. In this paper, various singularity-free algorithms, which are appropriate to parallel haptic system, will be discussedand evaluated.

• Journal of Advanced Marine Engineering and Technology
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• 제30권2호
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• pp.231-238
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• 2006

The performance of free-breathing polymer electrolyte membrane fuel cell (PEMFC) was studied experimentally and the effect of cathode separator structure on the cell performance was investigated. Cathode separators were used for the cell with $18cm^2$ active area. In channel type, the contact resistance is low, and the nature convection. which is strongly affected by the cross-sectional shape of cathode separator channel, is dominant in a cell performance. The maximum power density with $18cm^2$ active area is $105mW/cm^2$ using the 10mm depth and 2mm width channel. A computational analysis was optimum structure of free-breathing channel type PEMFC for robotic application.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.967-969
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• 2003

인터넷의 급속한 발전으로 네트워크 보안을 위하여 침입차단시스템의 사용이 보편화 되고 있다. 최근에 많이 사용되고 있는 Linux나 FreeBSD 커널(Kernal) 기반의 침입차단시스템은 게이트웨이 모드(Gateway Mode)와 브리지 모드(Bridge Mode)를 선택적으로 지원한다. 본 연구에서는 FreeBSD 커널에서 게이트웨이 모드와 브리지 모드를 동시에 지원하는 침입차단시스템을 구현하였다. 응용서비스(Application Service)에 대하여 별도의 프록시(Proxy) 없이 침입차단시스템을 구축할 수 있는 확장성이 뛰어난 네트워크 구축 방안을 제안한다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.20-22
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• 2007

Welding-induced buckling distortion at the free edge of thin-plated panels has been studied. Welding distortion at free edges causes the additional man hours to straighten for the easy adjusting works of the following assembly stage. Therefore, it is necessary to develop a free-edge distortion control method. It is the purpose in the study to evaluate the effectiveness of buckling distortion prevention of the current design practice and design modification.

• Current Photovoltaic Research
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• 제3권4호
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• pp.126-129
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• 2015

Over the last two decades, quantum dot (QD) solar cells have attracted much attention due to the unique properties of QDs, including band gap tunability, slow hot electron cooling, and multiple exiton generation effect. However, most of the QDs employed in photovoltaic devices contain toxic heavy-metals such as cadmium or lead, which may limit the commercial application. Therefore, recently, heavy-metal-free QDs such as Cu-In-S or Cu-In-Se have been developed for application in solar cells. Here, we review the research trends in heavy-metal-free QD solar cells, mainly focusing on Cu-In-Se QD-sensitized solar cells (QDSC).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.300-306
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• 2004

This paper is concerned with the application of perturbation method to the dynamic analysis of free-free beam. In general, the rigid-body motions and elastic vibrations are analyzed separately. However, the rigid-body motions cause vibrations and elastic vibrations also affect rigid-body motions in turn, which indicates that the rigid-body motions and elastic vibrations are coupled in nature. The resulting equations of motion are hybrid and nonlinear. We can discretize the equations of motion by means of admissible functions but still we have to cope with nonlinear equations. In this paper, we propose the use of .perturbation method to the coupled equations of motion. The resulting equations consist of zero-order equations of motion which depict the rigid-body motions and first-order equations of motion which depict the perturbed rigid-body motions and elastic vibrations. Numerical results show the efficacy of the proposed method.

• International Journal of Contents
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• 제10권3호
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• pp.1-8
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• 2014

In this paper, we collect and analyze the status of mobile phone applications (hereafter apps) in the healthcare and fitness category of the Apple iTunes App Store and Google Play Store. We determine the number of apps and analyze statistical aspects such as classifications, age rating, fees, and user evaluation of the popular items. As of September 30, 2013, there were 236 popular apps available from iTunes. Google Play offered 720 apps. We discover that apps for healthcare and fitness are diverse. Apps for physical exercise have the greatest popularity. The proportions of apps that are suitable for all ages among the Google and iTunes popular apps are 55.8% and 89.4%, respectively. The user evaluation of apps in iTunes is relatively less positive. We determine that the proportion of paid apps to free apps in Google is higher than that of the apps in iTunes. We perform hypothesis tests and find statistically significant differences in age rating and perceived satisfaction between the apps of the Apple iTunes App Store and Google Play Store. However, we find no meaningful differences in the classification and price of the apps between the two app stores. We perform hypothesis tests to verify the differences in age rating and perceived satisfaction between the paid and free apps within and across the Google Play Store and iTunes App Store. There are statistically significant differences in the age rating between the paid and free apps in the Google play store, between the Google free and iTunes free apps, between the Google paid and iTunes paid apps, between the Google free and iTunes paid apps, and between the Google paid and iTunes free apps. There are statistically significant differences in the perceived satisfaction between the Google free and iTunes free apps, between the Google paid and iTunes paid apps, between the Google free and iTunes paid apps, and between the Google paid and iTunes free apps.

• International Journal of Contents
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• 제14권3호
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• pp.46-52
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• 2018

The objective of this study was to determine the status of star chart game applications in the Google play store in Korea. The share of game genres in paid and free star charts of game applications was searched. Also, the average reviewer's rating, average number of reviews, and average age rating based on the genre of paid and free star charts of game applications, and the average price of paid applications based on genre were analyzed. Hypothesis tests for the differences in average reviewer's rating, average number of reviews, average age rating according to the genre of game applications were performed. Also, hypothesis tests for the differences in average reviewer's rating, average number of reviews, average age rating between the paid and free game applications along with the hypothesis test for the differences in price according to the genre of paid game applications were performed. Lastly, hypothesis tests for the correlation between the start chart ranking and number of reviews in association with the correlation between the start chart ranking and reviewer's rating were performed. Statistically significant differences in average reviewer's rating, average number of reviews, average age rating according to the genre of game applications, and between the paid and free game applications were verified. However, the correlation between the start chart ranking and number of reviews in association with the correlation between the start chart ranking and reviewer's rating were not statistically significant.