• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.643-646
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• 2011

스마트 폰의 보급과 함께, 무선 네트워크에서의 데이터 사용량이 급격하게 증가하고 있다. 이로 인해 발생하는 서버의 과부하와 그로 인한 속도 저하를 해결하기 위하여, 본 논문에서는 Wi-Fi 에드혹 네트워크를 이용한 통신을 3G 통신망에 효율적으로 접목하는 기법을 제안한다. 본 논문에서는 하나의 파일을 다수의 파일 블록으로 나누어 받는 방식을 이용하며, Wi-Fi 애드혹 네트워크를 이용해 주변에 있는 다른 이용자에게 파일 블록을 요청함과 동시에 자신이 가진 파일 블록 테이블을 다른 이용자에게 전달해주는 기법을 제안한다. 이를 이용하여 상대가 가지고 있을 것이라고 추측되는 파일 블록을 알아내어, 요청할 수 있다. 그 결과, 제안된 알고리즘이 3G와 Wi-Fi 에드혹 네트워크를 랜덤으로 이용하는 방법 대비 73%의 속도 향상과 43%의 3G 사용량 감소 효과를 보임을 확인할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2801-2808
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• 2010

The technology of WiBro, combining advantages of high speed internet and wireless internet provides the effectiveness and convenience provided by broadband and convergence. WiBro has developed due to supports of the related industries. The advancement of WiBro have created driving force for network advancement. WiBro is a niche market among high speed Internet, wireless LAN, Mobile phone, wireless internet. Through building relationship between market share and the existed telecommunication service, WiBro could improve the convenience of users. The security controls have to be built considering vulnerabilities of WiBro. Based on the study, the architecture of WiBro was suggested through reviewing the vulnerabilities and security controls in the wireless network and wire network. The appropriate security measures to be applied in the environment of WiBro. The outcomes of the study could improve the usage of WiBro.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.441-450
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• 2006

WiBro(Portable Internet Service) is service being capable to provide a high data rate wireless internet access with Personal Subscriber Station under the stationary or mobile environment, anytime and any where. It will fill the gap between very high data rate wireless local area networks and very high mobility cellular systems. The security is an important point of WiBro providing high data and mobile wireless services. This paper proposes user authentication mechanism of WiBro wireless networks applied EAP-AKA authentication protocol. As a result of Wireless authentication based on EAP-AKA, this mechanism is capable to be used in WiBro-WLAN-3GPP interworking scenario as well as the WiBro authentication mechanism.

• Proceedings of the Costume Culture Conference
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• 2005.04a
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• pp.104-107
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• 2005

• Journal of Communications and Networks
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• v.11 no.4
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• pp.375-383
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• 2009

The WiMedia alliance has specified a distributed medium access control (WiMedia MAC) protocol based on ultra wideband (UWB) for high data rate WPANs (HR-WPANs). The merits of WiMedia MAC such as distributed nature and high data rate make it a favorite candidate in HR-WPAN. Although QoS parameters such as the range of service rates are provided to a traffic stream, the WiMedia MAC is not able to use the QoS parameters and to determine or adjust a service rate using the QoS parameters for the traffic stream. In this paper, we propose a fair and adaptive resource allocation method that allocates time slots to isochronous streams according to QoS parameters and the current traffic load condition in a fully distributed manner. Although the traffic load condition changes, each device independently recognizes the changes and calculates fair and maximum allowable service rates for traffic streams. From the numerical and simulation results, it is proved that the proposed method achieves high capacity of traffic streams and fair QoS provisioning under various traffic load condition.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.291-293
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• 2012

급격히 증가하는 모바일 디바이스에 의한 모바일 데이터 요구량을 처리하기 위해 가장많이 고려되고 있는 IEEE 802.11의 WLAN은 셀룰러보다 높은 데이터 전송속도를 제공하지만 이동성이 고려되어있지 않다. 이에 본 논문에서는 Enterprise WLAN에서 IEEE 802.21 MIH 표준에 기반하여 Media Independent Information Server (MIIS)로부터 수신된 주변 AP들의 네트워크의 정보를 바탕으로 후보 엑세스 AP 네트워크를 선정 및 WiMAX에 make-before-break 핸드오버하는 방안을 제안한다. 제안하는 방안은 실제 Enterprise WLAN와 Mobile WiMAX 환경에서 이동하는 단말의 시간에 따른 TCP throughput에 대한 성능평가를 하였다. 이를 통해 제안하는 방안의 평균TCP throughput 성능이 9.04Mbits/s으로 기존 방안의 TCP throughput 성능 6.49Mbits/s보다 약 40%향상됨을 확인하였다.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.404-408
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• 1998

Yellow sand event has been studied using SeaWiFS data in order to examine the aerosol optical characteristics in the Yellow Sea and their influences on the atmospheric correction for the ocean color remote sensing. Two SeaWiFS images of April 18 and April 25, 1998, representing Yellow Sand event and clear-sky case respectively, are selected for emphasizing the impact of high aerosol concentration on the ocean color remote sensing. It was shown that NASA's standard atmospheric correction algorithm treats yellow sand area as either too high radiance or cloud area, in which ocean color information is not generated. SeaWiFS aerosol optical thickness is compared with nearby ground-based sun photometer measurements and also is compared with radiative transfer simulation in conjunction with yellow sand model, examining the performance of NASA's atmospheric correction algorithm in case of the heavy dust event.

• Korean Journal of Remote Sensing
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• v.19 no.3
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• pp.201-208
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• 2003

Much effort has been made in the radiometric calibration of the ocean scanning multispectral imager (OSMI) since after the successful launch of KOMPSAT-1 in 1999. A series of calibration coefficients for OSMI detectors were obtained in collaboration with the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary (SIMBIOS) project office. In this study, we ompare the OSMI level-2 products (e.g., chorophyll-a concentration) calculated from the NASA cross-calibration coefficients with the SeaWiFS counterparts. Sample study areas are some of diagonostic data sites recommended by the SIMBIOS working group. Results of this study show that the OSMl-derived chlorophyll-a concentration agrees well with the SeaWiFS counterpart in Case 1 water; however, differences become larger in Case 2 water.

• The Journal of Internal Korean Medicine
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• v.25 no.2
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• pp.320-328
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• 2004

Gastrectomy is the most common treatment for gastric cancer, but patients often suffer from post-operative side effects. This study describes the clinical effects of HyangSaPyungWiSan on a pateint who suffered from nausea, vomitting, indigestion, headache, abdomen pain, and loss of appetite after his gastrectomy. The patient undewent a gastrectomy due to gastric cancer, and HyangSaPyungWiSan was used to treat all thses symptoms. This study suggests that treatment with HyangSaPyungWiSan is effectious for such aftereffects of gastrectomy as nausea, vomitting, indigestion, headache, abdomen pain, and loss of appetite.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.67-73
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• 2011

With the rapid growth of recent smart phone technology, the interests for the design of online game in mobile computing environment are highly focussed on with great attention. Smart phone as a mobile terminal device, however, has many restrictions for implementing online mobile game since the limitation of relatively low performance of a processor, low resolution of GUI, small memory spaces, and short battery power. Therefore, most of games are very restricted on online and multi-play functions. In this paper, we design and implement mobile online game app in component based smart phone environment in order to take over these restrictions in mobile environment. Especially, the implemented mobile game is able to play online game among Wi-Fi based game server and another smart phone.