• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.577-584
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• 2010

In this paper, a cooperative MAC protocol that is reliable over bad wireless channel environments and thus can enhance the system performance much more is proposed. Its performance is evaluated with the computer simulation. The system throughput and average waiting delay are used as performance measures. According to numerical results, the proposed MAC protocol provides better system throughput by 24% than the traditional rDCF scheme. From the average waiting delay point of view, when the number of terminals is small, the proposed MAC protocol has the better performance in an average view-point than the rDCF scheme. However, when the number of terminals is large, the proposed MAC protocol provides a little worse performance than the rDCF scheme. That is because, when the number of terminals is large, the dominant factor affecting the system performance is channel contention procedure, which results in lots of collisions. However, if the queuing delays in the waiting buffers are included for calculating the average waiting delay, then the total system delay will be smaller than the rDCF scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.951-957
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• 2010

In this thesis, we propose a font development system that can handle various fonts efficiently in the GSM mobile terminals. The ASCII code was widely used to express characters on the computer in the beginning but it has limitation for representing many characters. Recently, Unicode was developed to add more characters. Researches on code systems are still on going to express the characters more efficiently. Attempt of applying this kind of Unicode to the mobile terminal didn't work efficiently since there are too many characters for various languages. In this research, we designed and developed a font system to shorten processing time and efforts that apply Unicode to mobile terminals to solve these problems. Our system can save processing time and efforts since it reduces the meaningless processing compared to other systems.

• The KIPS Transactions:PartD
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• v.9D no.3
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• pp.501-510
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• 2002

A various multimedia application services should be developed with techniques of high speed networks and computer. Among these, video-conference system over Internet is useful and important, and the standardization for it should be showed in ITU-T H.323. H.323 standardization consists of four components such as Terminal, MCU(Multipoint Control Unit), Gatekeeper, and Gateway. Among these, the functions of Gatekeeper are as follows, firstly the address translation service to translate the alias address into the IP address, secondary conference admission control service to control of conference start and termination, thirdly bandwidth management service for H.323 terminals. In this paper, we implemented the Gatekeeper for an efficient management of video-conference components in Internet environment, and will introduce our system. As the experimental results with CUSeeMe and Netmeeting which are well-known H.323 terminal, it is known that our gatekeeper should be satisfied with H.323 standardization.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.498-508
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• 2008

TECA(Terminal Cabin) has train information, fault display, maintenance function and training function for driver, as sub-device of Seoul-Pusan Express train's on-board computerized device. Concerning KTX train's driving, signal driving is required for high speed driving, and it is true that we have difficulty in troubleshooting and acquisition of basic information through long train and one-man driving. Therefore, rapid and correct processing about various information and TECA device for maintenance are indispensable for its utilization. But there is not study example in hardware, maintenance about this device and device development according to new requirements. Therefore, this study will help understanding of driver assistance terminal device's maintenance performance development, describing TECA's basic functions necessary for device development and its requirements. Accordingly, I suppose that this thesis will be utilized to complete specification, necessary for new driver assistance terminal device development.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.823-826
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• 2008

This paper will show how to design home network management system in the wired/wireless environment using graphical language LabVIEW, J2ME and to apply the design to monitoring and remote controling for the information devices at home. This paper also provides with efficiency of device control and current status check according to the circumstances of administrators by constructing the wire/wirelessly integrated administration system. It means the administrators can access to central administration server and acquire the control right through web being able to operate the system with flexibility and can access to the server without computer whenever, wherever they need to control and administrate it through this wired/wireless unit easily.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.740-744
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• 2003

Nowaday, a system development which does to the foundation is drawing the concern that new foundation technique for Web application development. Various terminal is a service supply is not easy. Because of the protocol to use differs for every each terminal, We must make a server program the each every protocol. A reservation system setup itself was not easy at the reason. Because of the importance of the field which is the mobile have been enlarged to a day, We have been raised in reality to the problem to solve. This facility which the technique supports in the paper to use, We can offer the service to server program. The design will try to implement about the reservation system besides.

• Journal of Broadcast Engineering
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• v.17 no.2
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• pp.262-269
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• 2012

Hybrid-ARQ and opportunistic relaying are the widely used schemes for obtaining diversity gain in wireless communications. In opportunistic relaying, channel state information(CSI) between relays and destination is required to select the best relay. But if the destination moves very fast, the CSI becomes outdated. In this paper, performance of hybrid-ARQ based opportunistic relaying with outdated CSI is analyzed in outage probability and throughput perspective. The analysis is verified by computer simulations.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.157-163
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• 2016

This paper presents Finger Keyboard which detects the user's key types on a keyboard drawn on the paper using a video camera. The Finger Keyboard software was written in standard C/C++ language and thus easy to port to other computing environments. We installed a popular USB-type web camera on a Windows PC and implemented the Finger Keyboard as a Windows application which detects key typing and then injects the key code into the message queue of the Windows operating system. Also we implemented the Finger Keyboard on the Raspberry Pi 2 embedded computer with a dedicated camera and connected it to the Android device as an external keyboard through the Bluetooth. The result of experiments showed that the average ratio of recognition success is around 80% at the typing speed of 120 characters per minute.

• Journal of Digital Contents Society
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• v.9 no.3
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• pp.509-516
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• 2008

We propose the Hybrid Rendering model to support multi-resolution for computer graphics. LOD method for computer graphics system considering performance of device environment and end-user preference usually adopts mesh resolution, mipmap in texture rendering, or oct-tree data structure in ray tracing. The hybrid rendering model, as a local shading model combining Gouraud shading model and a flat shading model, applies a proper shading method to each of polygons consisting of an object. This method can be an effective alternative to reduce real-time rendering time so that it can be utilized in real time adaptive service of computer graphic contents among various device environments under ubiquitous environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.755-761
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• 2002

Before the Internet was available, most application programs were executed using terminals, connected to host computers, as standard input output devices. The Internet is popular today and many services are provided on web browsers connected to the Internet. Since the standard I/O method used for terminals is different from the communication I/O methods used for web browsers, it is not possible to execute many application programs developed for the conventional terminals on web browsers. In this paper, we describe Web Input Output(WEBIO) library that enables application programs conventional on terminals to be executed on web browsers by recompilation without source modification. The WEBIO libraries for C and Prolog languages have been developed and they are under test now.