• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.749-756
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• 2005

In the near future, we can access the information whenever we want, wherever we use because almost devices in ubiquitous environment are connected by either wired or wirelss networks. Especially, u-Learning which emphasizes on pedagogical property is enable to improve learning abilities. As researches of the previous u-Learning, there have been learning by mobile devices such as PDAs as well as the smart classroom which makes the remote students participate in the existing class. However, these researches have not satisfied pedagogical, cooperative and ubiquitous properties yet. Thus we suggest the framework for both local and mobile classroom, which can make the properties easy to satisfy.

• Journal of the Korea Computer Industry Society
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• v.4 no.12
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• pp.911-922
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• 2003

Nowadays, we can easily find student who study through computer in e-teaming environment. But, although e-teaming system has strong point that overcomes limitation of distance and time, many students give up their study through on-line learning. In this study, we developed On-Line learning motivation model, and designed and developed on-line quiz game loaming system. Thus we can find student's teaming motivation was grow up through student's interaction. Also, we find on-line quif game learning system had many information that explain student's status about their knowledge.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1382-1390
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• 2010

We can see interactions between rigid body and fluid every day, anywhere. This kind of rigid body-fluid simulation is one of the most difficult problems in physically-based modeling, mainly due to heavy computations. In this paper, we present a real-time dynamics model for simulating stone skipping, which is a popular rigid body-fluid interaction in the real world. In comparison to the previous works, our improved dynamics model supports the rotation of the stones and also computes frictional forces with respect to the air. We can simulate a realistic result for various user input by using proposed model. Additionally, we present a water surface model to show more realistic ripples interactively. Our methods can be easily adapted to other interactive dynamics systems including 3D game engines.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.3
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• pp.160-169
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• 2006

The goal of this paper is to propose a way to register agents so that makes users or autonomousagents to find target agents more conveniently and efficiently. In order to achieve this goal, we first survey the key technologies such as UDDI, ebXML, FIPA DF. As the results, we designed a new agent legistry/repository system based on ebXML technologies. We introduce our agent/repository system for wide area network and describe how to use our system for agent registering and searching target agents for communications. Finally, we give an example to illustrate a typical scenario in which user receives the results from our proposed agent registry/repository system and evaluate its characteristics in terms of advantage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1784-1788
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• 2012

In this paper we considered condition for keep standard error probability in optical transmission system that applied on-off keying transmission which are modulated amplitude along the signal. we calculated received sensitivity of receiver in on-off keying transmission for optical detector have quantum efficiency belong 1 in optical transmission system. For BT is over 30, the number of photon is belong 10000 for maintain standard error probability. also we considered Also, we install a preamplifier to the receiver for considering the low output may be used with a light that was able to get results.

• KIISE Transactions on Computing Practices
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• v.20 no.11
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• pp.586-591
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• 2014

In recent years, we can access to video contents anywhere and at any time. Therefore distributed video is easily copied, transformed and republished. Since it brings copyright problem, similarity/duplicate detection and measurement is essential to identify the excessive content duplication. In this paper, we analysed various discernment of video which has been transformed with various ways using MPEG-7 Video Signature. MPEG-7 Video Signature, one of video copy detection algorithms, is block based abstraction. Thus we assume Video Signature is weak for spatial transform. The experiments show that MPEG-7 Video Signature is very weak for spatial transform which could occur general as we have assumed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.604-611
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• 2007

In this paper, we present an analysis of the throughput when there are multiple piconets and WLAN sharing the ISM bands. The analysis takes channel propagation characteristics and the capture effect. We also propose an algorithm which can be used to reduce the amount of channel scanning. By using traffic prediction of the interfering WLAN, we are able to maintain a reasonable performance in terms of fraction of time channel is wasted due to collisions or unused channel. Through computer simulation, we demonstrate that the proposed algorithm achieves reduced scanning frequency.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.79-86
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• 2009

In this paper, we propose a new clustering scheme that provides optimal data aggregation effect and reduces energy consumption of nodes by considering the density of nodes when forming clusters. Since the size of the cluster is determined to ensure optimal data aggregation rate, our scheme reduces transmission range and minimizes interference between clusters. Moreover, by clustering using locally adjacent nodes and aggregating data received from cluster members, we reduce energy consumption of nodes. Through simulation, we confirmed that energy consumption of the whole network is minimized and the sensor network life-time is extended. Moreover, we show that the proposed clustering scheme improves the performance of network compared to previous LEACH clustering scheme.

• Korean Journal of Optics and Photonics
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• v.8 no.5
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• pp.438-442
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• 1997

In this study we report the effect of melt instability on the Liquid Phase Epitaxy. We made a new graphite boat of the structure relieving the instability of melt. It did not improve the uniformity of each layers but also reduced the thickness of growth layers and the deviation of the thickness over 1/2, 1/3 respectively. Moreover, we could get the growth layer of about 80$\AA$. With the point of melt stability in view we investigated the effect of InP seed used in two phase solution method. It is concluded that the quality of layers grown by the single crystal is superior to that by the poly crystal in two phase solution method.

• The Korean Journal of Applied Statistics
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• v.29 no.6
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• pp.1061-1075
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• 2016

In this paper, we discuss various methods to visualize high dimensional large-scale data and review some issues associated with visualizing this type of data. High-dimensional data can be presented in a 2-dimensional space with a few selected important variables. We can visualize more variables with various aesthetic attributes in graphics or use the projection pursuit method to find an interesting low-dimensional view. For large-scale data, we discuss jittering and alpha blending methods that solve any problem with overlapping points. We also review the R package tabplot, scagnostics, and other R packages for interactive web application with visualization.