• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.1
• /
• pp.13-19
• /
• 2012

The use of RFID is recently increasing for the realization of Ubiquitous computing. Reducing the process time of tag recognition is crucial as RFID system has to recognize multiple objects in a short amount of time. In this manuscript, therefore, an effective scheme using multi-reader is suggested to improve processing speed for tag authentication in RFID system. According to the result of performance analysis, the processing time required for tag authentication was drastically reduced in multi-reader environment than it was in a single reader. Consequently, the use of the suggested scheme cuts down on the processing time while identifying tags by using multi-reader and bring about overall performnce improvement of RFID system.

• Journal of Digital Convergence
• /
• v.10 no.6
• /
• pp.225-230
• /
• 2012

When a car accident happened, the accident vehicle should broadcast a safe message to its neighbors in multi-hop. However, the pure flooding is difficult to protect a chain-reaction collision because of the frequent collision and the communication delay. To solve this problem, we proposes a back-off algorithm applied to the estimation of the neighbor node count using the t-distribution. And we proposes a MAC protocol preventing the communication delay by separating the neighbor's count collection channel and data channel. As a result, we show the frame reception success rate of our protocol improved more 10% than the previous protocol.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.10
• /
• pp.104-110
• /
• 2005

In this paper, unmanned vehicle system and VFF algorithm development with vehicle dynamics is the main topic as a part of Intelligent Transportation System. Unmanned vehicle system is classified by vehicle system and control system. Authors used RC servo motor for longitudinal control via throttle angle, shift lever control, and brake control. For lateral control, authors used step motor, equipped with reduction gear. Unmanned vehicle has nine ultrasonic sensors in front of the unmanned vehicle. After the microcontroller computes the distance between unmanned vehicle and obstacle, the control computer calculates the steering angle enough to avoid the obstacle.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.13 no.2
• /
• pp.95-101
• /
• 1999

The electron energy distributions function were analysed in sulIitur hexaflowide at E/N : 500~800(Td) for a case of non-equilibrium region in the nran electron energy. This papa- describes the electron transport characteristics in $ SF_6$ gas calculated for range of E/N values from 150~800(Td) by the Monte Carlo simulation and Boltzmann equation Irethod using a set of electron collision cross sectioos determined by the authors and the values of electron swarm parameters. The results gained that the value of an electron swarm parameter such as the electron drift velocity, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients agree with the experimental and theoretical for a range of E/N. The properties of electron avalanches in an electron energy non-equilibrium region.region.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2005.11a
• /
• pp.471-474
• /
• 2005

For the purpose of objective and scientific inspection, traffic accidents should be appraised and inspected by righteous material evidences, computer simulation, and studies such as automobile engineering, traveling and collision accident dynamics, road and traffic engineering. In this paper, it displays the results of studying cases with the reasons of traffic accidents by analyzing and studying automobile kinetics, real traffic accidents and the results of in scientific and objective ways. In this paper, it is proved that with compared by dry and wet road surface condition, the transient brake time of wet condition is longer than dry road condition. Moreover, compared with unpacked road condition and packed road condition. unpacked road condition is shorter than packed road condition using computer simulation.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.1
• /
• pp.44-52
• /
• 1987

For the favorable performance of a D.I. diesel engine, it is important to improve the mixture formation process and the ensuing early stage of combustion process. In the present paper, high speed photography was employed to investigate the effectiveness of a cavity digged in a piston crown for some more useful utilization of air. The cavity would function to improve mixing of fuel and air by the increase of turbulence of air and by the impingement of fuel spray on the cavity wall. The results obtained are summarized as follows: (1) From an aspect of thermal efficiency, it is effective to inject the spray tangentially to the cavity wall to enlarge the area of spray evaporation. (2) some deductions obtained from previous investigations using a hot air stream duct are supported by the present results. For example, it is effective for the quick development of flames throughout the combustion chamber to mix the evaporated fuel of main spray with the intermediates brought about by the early stage of combustion of the preceded auxiliary fuel spray.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.9
• /
• pp.2256-2270
• /
• 1998

The development of a high perfoffilance index system is crucial for the retrieval of information from large sets o[ data. In this study, a minimal perfect hash function (MPHF), which hashes m keys to m buckets with no collisions, is revisited. The MOS algorithm developed bv Heath is modified to be successful for computing MPHFs of large sets of keys Also, a system for generating MPHFs for large sets of keys is developed. This system computed MPHFs for several large sets of data more efficiently than Heath's. The application areas for this system include those for generating MPHFs for the indexing of large and infrequently changing sets of data as well as information stored in a medium whose seek time is very slow.

• Transportation Technology and Policy
• /
• v.5 no.1
• /
• pp.161-171
• /
• 2008

아시아의 도시교통사고는 빠른 인구증가와 경제성장으로 인한 자동차 보급 확대로 인해 OECD 국가에 비해 2${\sim}$3배 높은 수준으로 교통사고절감을 위한 대안 마련이 시급한 실정이다. 이에 본고에서는 ITS기반 도로교통 안전시스템의 정착을 통해서 아시아 도시의 공통된 교통안전문제를 해소하기 위한 공동대응방안을 제시하고 있다. 이를 요약하면, 첫째, 도로사고와 ITS관계를 규명하고 사고요인을 도로상에서 제거할 수 있는 ITS기술을 소개하였다. 교통사고원인의 95%가 운전자관련인자로 나타나 운전자관련 ITS요소기술(HMI 등)의 개발이 시급한 것으로 나타났다. 또한 현재 도로 안전분야에서 적용 가능한 실용기술로는 돌발상황관리시스템, 충돌경고시스템, 비상연락시스템, 단속시스템 등인 것으로 판단된다. 둘째, ITS기반 도로교통 안전시스템의 조기 정착을 위해서는 기존 조직 법 제도의 정비가 필요하다. 아시아 도시에서는 ITS 도입 초기 정부주도형으로 추진하는 것이 바람직한데, 이를 위해서는 정부조직 내 ITS 전담기구 (Headquarter)를 신설하고, 도로안전 ITS관련 법령 및 ITS Master Plan에 근거한 권한과 사업, 예산을 확보해야한다. 또한 인프라 및 ITS 구축 운영과 함께 RSA(Road Safety Audit)와 같은 선진안전제도 시스템을 벤치마킹하여 국내 현실에 맞도록 접목시켜 나가야한다. 셋째, 교통관제 (광역)정보센터, 버스센터, 구간속도단속 등 혁신적인 도로안전사업을 지속적으로 발굴 확충하여 노하우를 축적해야 한다. 넷째, 아시아 도시의 공통된 교통문제를 해소하기 위한 공동대응방안을 마련하기 위하여 각국의 노하우를 전파하고 공유하는 창구로 아시아 태평양지역 ITS포럼을 더욱 육성해야 하겠다.

• Journal of Advanced Navigation Technology
• /
• v.15 no.6
• /
• pp.977-985
• /
• 2011

Airborne separation assurance is a key requirement for Free Flight Airspace operations, This paper study the feasibility of airborne separation assurance for free flight Airspaces operations by evaluating the efficiency measurement models. Three qualitatively different methods are utilized; one based Ground and Air conflict probability model, other based Dynamic Density model. the other based Direct operating cost model. The evaluation is Direct Operating Cost model and Two metrics are utilized for the efficiency measurements; airborne separation assurance performed quite well in the Free Flight evaluation; (1) 2 scenario of the conflict situations are resolved; (2) The MD-80 flight peformed separation assurance and efficiency, Not only appling for geometric method algorithm is more efficiently than potential method, but also the most efficiently geometric combined method.

• Proceedings of the KAIS Fall Conference
• /
• 2011.12b
• /
• pp.382-384
• /
• 2011

최근 오일샌드, 극지유전, 심해저자원 등 극한지 자원개발이 활발해짐에 따라 수요가 증대되고 있는 극한지용 내마식 소재는 내마식성과 함께 저온 인성이 요구되고 있다. 철계 합금에서 관찰되는 변형유기 마르텐사이트 상변태는 입자의 충돌에 의한 충격을 흡수하고 소재의 표면을 가공경화시켜 내마식성 향상 및 저온 인성에 기여할 수 있을 것으로 기대되고 있지만 합금조성의 정교한 제어가 필요하기 때문에 오버레이 용접에 적용하기 위해서는 모재와의 희석률을 제어하는 방안이 필요하다. 용접플럭스 설계기술은 용접시 금속이행모드, 용융풀 거동 등과 같은 용접현상 제어를 통해 오버레이 용접재료의 용접성과 용접비드형상, 용접부 희석률을 최적화할 수 있는 기술이다. 본 연구에서는 내마식 고인성 오버레이 용접재료의 개발을 위해 다양한 용접플럭스를 첨가한 메탈코어드 와이어를 제조하고 일정 송급속도에서 GMA 용접시 용접전압과 용접전류 간의 관계를 분석하여 용접플럭스가 아크현상 및 희석률에 미치는 영향을 조사하였다.