• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.53-56
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• 2015

In this paper, we want provide improved services with faster transmission, IEEE 802.11n was standardized. A-MPDU (Aggregation MAC Protocol Data UNIT) is a vital function of the IEEE 802.11n standard, which was proposed to improve transmission rate by reducing frame transmission overhead. In this paper, we show the problems of TCP retransmission with A-MPDU and propose a solution utilizing the property of TCP cumulative ACK. If the transmission of an MPDU subframe fails, A-MPDU mechanism allows selective re-transmission of failed MPDU subframe in the MAC layer. In TCP traffic transmission, however, a failed MPDU transmission causes TCP Duplicate ACK, which causes unnecessary TCP re-transmission. Furthermore, congestion control of TCP causes reduction in throughput. By supressing unnecessary duplicate ACKs the proposed mechanism reduces the overhead in transmitting redundant TCP ACKs, and transmitting only a HS-ACK with the highest sequence number. By using the RACK mechanism, through the simulation results, it was conrmed that the RACK mechanism increases up to 20% compared the conventional A-MPDU, at the same time, it tightly assures the fairness among TCP flows.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.109-112
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• 2007

Currently was Convergence time of broadcasting and communication with development of information communication technology and internet infra environment. The superhigh speed internet about under using there is IPTV where it provides the broadcasting contents with broadcasting and communication Convergence service. Digital broadcasting it makes various broadcasting in one stream and it transmits, and about under analyzing it uses Channel information which is included in broadcasting and broadcasting information from the terminal. But, IPTV transmits each broadcasting in multicast methods, therefore the possibility of knowing all Channel information and broadcasting information from the terminal it is not there is a problem point. This paper hereupon it searched IPTV broadcasting information from the terminal and in order to support a channel selection from IPTV broadcasting streams SI about under extracting SD&S XML documents it created and it transmits with the distant multicast the system which plan and it embodied.

• International Commerce and Information Review
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• v.4 no.2
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• pp.77-96
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• 2002

Through the new round DDA(Doha Development Agenda) negotiations which started in Doha/Qatar conference in November, 2001, service industries have been included in the category of international trades. An electronic commerce cannot be exceptional in this field. The 21st century is largely recognized as the era of globalization, knowledge, and information. To make effective and competitive strategy in this century, it is essentially required to organize Network. OPEN, and FU-PLEX. That is why our government also has been promoting this field since years before, now 10,000,000 people in Korea have joined superhighway internet networks. Korea became the top internet-developed country in the world. As a side-effect of this internet spread into our life, however, there is serious problem we are now faced against. That is the outflow of private information through electronic commerce and other cyber transactions. It has caused many social problems to be rapidly on the rise these days. We are now desperately required to struggle continuously to make a solution for that. Taking the precedent case of Germany and United States which are currently recognized as high-leveled country in protection of private information, we have to come up with legal and technical measures and at the same time, to escalate the social consciousness about private information protection.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.554-559
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• 2007

최근 인터넷 관련 기술의 급속한 발전으로 사람들의 다양한 사회적, 경제적 행위들이 인터넷을 기반으로 확대되고 있다. 특히 우리나라의 경우 초고속 통신망의 확산과 더불어 인터넷 쇼핑몰과 상거래시장 또한 빠르게 성장하였다. 이러한 상황에서 인터넷을 매체로 하는 광고기법 또한 다양하게 적용되고 있는데, 인터넷을 통한 광고 효과를 극대화하기 위해 인터넷 신문기사 주변에 배치된 배너광고, 팝업광고 등 여러 가지 시도들이 있어왔다. 이러한 시도들은 인터넷 사용자의 편의에 대한 고려보다는 광고내용을 얼마나 잘 전달할 수 있는가에 초점이 맞추어져 있었다. 그러나 광고내용이 잘 전달된다 하더라도 소비자가 그 광고에 대해 불쾌감을 느끼게 된다면 과연 인터넷 광고효과가 높다고 말할 수 없을 것이다. 예를 들어, 팝업광고에 대한 대응책으로 개인적으로 팝업 블록커(pop-up blocker)를 사용하겠는가에 대한 설문조사 결과를 보면 사람들이 팝업 블록커를 이용해서라도 팝업광고를 피하고자 하는 비율이 77%에 달한다는 것을 알 수 있다. 실제로 Windows XP 서비스팩 2 이후의 버전은 인터넷 사용자들의 편의를 위해 자동 팝업 차단기능을 갖추고 있는 실정이다. 팝업광고를 통해 아무리 높은 정보전달 효과가 발생한다 하더라도 사용자들은 팝업광고에 대하여 거부감이나 부정적 감정을 느낄 수 있다. 그리고 광고정보가 전달된다 하더라도 팝업광고에 대한 사용자들의 불편함이 그 광고에 대한 부정적 감정으로 전이되어 광고대상에 대한 이미지에 악영향을 미칠 수 있음에 유의해야 한다. 그러므로 광고효과는 극대화하면서, 혹은 기존의 수준을 유지하면서 광고에 대한 거부감을 줄인 광고형태를 찾기 위한 다양한 노력들이 필요하다. 이를 위해 본 연구에서는 인터넷 신문기사에 첨부된 광고에 대한 사용자의 거부감을 줄일 수 있는 새로운 광고 제시 방식을 찾고자 일반적으로 사용되는 배너와 팝업 등 두 가지 광고 제시 방식과 전면에 돌출하지 않는 형태로 인터넷 신문기사의 배경에 삽입된 광고 제시 방식을 비교하였다. 그 결과, 인터넷 신문기사 영역의 주변 특정 부분(코너나 중간 부분 등)에 광고를 삽입한 배너 형태의 광고와 인터넷 신문기사 위에 광고가 돌출 등장하여 콘텐츠를 가리는 팝업 형태의 광고 제시 방식보다 새롭게 제안된 백그라운드 형태의 광고 제시 방식이 인터넷 신문기사를 읽는 사용자에게 거부감을 줄이며 동시에 광고효과를 유지할 수 있음을 확인하였다. 이러한 결과를 인터넷 광고 제시 방식으로 활용한다면 인터넷 사용자에게 콘텐츠를 방해하여 발생하는 명시적인 거부감(explicit negative attitude)을 줄이면서도 암묵적인(implicit) 광고효과를 얻을 수 있을 것이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.2
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• pp.77-85
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• 2014

Recently, utilization of MIMO(Multi-Input Multi-Output) system using array antennas is evaluated significantly according to the extension of high-capacity and high-speed communication services. However, MIMO system has disadvantages such as high-complexity and high-power-consumption, because RF(Radio Frequency) chain is required as antenna number, and several array antenna is used in conventional MIMO system. In order to solve these problems, research about beamspace MIMO system using ESPAR(Electronically Steerable Parasitic Array Radiator) antenna that has single RF chain by using one active antenna and several parasitic elements has been studied actively. Beamspace MIMO system using ESPAR antenna is possible to solve the problems of conventional MIMO system, because this system is composed by single RF chain. In this paper, in order to improve the system security, chaos communication algorithm that has characteristics such as non-periodic, non-predictability, easy implementation and initial condition is applied to QPSK (Quadrature Phase Shift Keying) modulated beamspace MIMO system. We design the chaos QPSK modulated beamspace MIMO system, and evaluate SER performance of this system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.191-200
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• 2007

As the IEEE 802.11 WLAN has widely installed as a high-speed wireless network information infrastructure, there has been growing interest in both security and mobility of mobile terminals. However, for the case of mobile terminal employing IEEE 802.11i security standard, it is known that the user authentication procedure of IEEE 802.1x for stronger security enforcement may, due to its large delay, not be suitable for real-time multimedia communication. In this paper, we have proposed fast authentication method to resolve the above authentication delay problem, and verifies its performance via simulation analysis. Mobile terminals can get AP information reliably, and selectively execute authentication in advance during handover, which results in fast user authentication. In addition, by effectively managing the authentication information in mobile terminal, which are distributed in advance for pre-authentication, the problem of long-time revelation of authentication information has been solved.

• Proceedings of the Technology Innovation Conference
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• 2003.06a
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• pp.90-107
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• 2003

참여정부의 출범과 한께 과학기술계에서는 동북아 과학기술 허브 구축방안 논의가 활발히 진행되고 있으나, 현재까지 이러한 논의는 법제도의 정비 및 과학기술특구 건설 등의 이슈에 한정되고 있는 실정이며, 더욱이 이를 뒷받침할 실증적 연구는 미미하다. 허브란 개념이 네트워크에서의 중심성(centrality)을 의미 하며, 현재 및 미래의 과학학기술협력 네트워크 발전에 정보통신기술이 중요한 역할을 수행함을 고려할 때, 우리나라의 초고속통신망 인프라를 십분 활용한 차세대 과학기술 정보인프라의 구축을 통한 동북아 사이버 연구네트워크상의 허브화(궁극적으로는 e-Science의 허브화를 지향)는 지역 클러스터 건설을 통한 물리적 허브화 못지 않게 중요하다 하겠다. 본 연구는 먼저 네트워크 분석기법을 동아시아의 과학기술협력 네트워크에 적용하여 주요 네트워크 지수를 실증적으로 진단하고, 특히 이를 유럽연합의 과학기술협력 네트워크의 패턴과 비교 분석하였다. 유럽 연합은 1984년부터 과학기술 협력 프로그램인 Framework Program을 시작하여 일찍부터 역내 과학기술협력 프로그램을 운영해 온 경험을 가지고 있고, 2000년부터는 자발적 협력과 네트워킹을 통해 유럽의 연구 개발 활동을 통합·조정하기 위해 새롭게 제안된 유럽 연구개발권 (European Research Area) 형성이 구체화되고 있어, 동북아 과학기술협력 네트워크를 건설하는데 좋은 벤치마킹 대상이라 할 수 있다. 이 보고서에서는 유럽 연구개발귄이라는 우산 아래서 유럽의 과학기술 활동이 조정 및 통합되는 과정을 살펴보고, 이를 위한 과학기술 정보인프라의 주요 기능을 컨텐트 (연구정보서비스와 메타데이터 표준), 시스템 (슈퍼 컴퓨팅, 광대역 네트워크, GRID), e-Science 응용연구 별로 살펴보았다. 끝으로 유럽의 경험을: 교훈삼아 동북아 e-Science 네트워크의 건설을 위한 정책적 시사점과 동북아 연구개발정보 Portal 및 APEC APGrid 연구망 등의 구체적인 정보인프라 구축방안을 도출하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.173-178
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• 2014

Smart devices linked to high speed networks enable us to obtain location dependent data at anywhere and anytime. In this environment, a wireless data broadcast system can deal with enormous data request from a great number of clients effectively. In order to set up an efficient wireless data broadcast system, various data scheduling and indexing schemes have been proposed. However, a simulation framework to evaluate the schemes is not reported yet. In this paper, we design and develop a simulation framework for a wireless data broadcast system. The developed simulation framework can evaluate quickly a wireless data broadcast system and has scalability to adopt various data scheduling and indexing schemes for wireless data broadcasting.

• Journal of the Korean Data and Information Science Society
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• v.26 no.5
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• pp.1035-1045
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• 2015

Recent studies in Big Data Analysis are showing promising results, utilizing the main memory for rapid data processing. In-memory computing technology can be highly advantageous when used with high-performing servers having tens of gigabytes of RAM with multi-core processors. The constraint in network in these infrastructure can be lessen by combining in-memory technology with distributed parallel processing. This paper discusses the research in the aforementioned concept applying to a test taxi hailing application without disregard to its underlying RDBMS structure. The application of IMDG technology in the application's backend API without restructuring the database schema yields 6 to 9 times increase in performance in data processing and throughput. Specifically, the change in throughput is very small even with increase in data load processing.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.317-324
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• 2016

WiMedia provides the data rate of up to 1Gbps, but the transmission range is restricted to approximately 10 meters. When constructing a multi-hop WiMedia network to extend its coverage, conventional hop-based routing may not guarantee satisfactorily the required QoS. We propose two QoS routing techniques for the WiMedia-based wireless mesh network. The proopsed QoS routing reflects the characteristics of TDMA-based WiMedia MAC and develops QoS extensions separately for on-demand routing and table-driven routing. Through simulations, we identify that the QoS routing shows better performance than the hop-based routing. It also turns out that the QoS on-demand routing and the QoS table-driven routing show conflicting performance results depending on the transmission power.