• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1693-1696
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• 2002

In this paper, we analyzed the performance of OFDM system based on IEEE 802.11a specification. First, we modeled the transmitter and receiver of OFDM (Orthogonal Frequency Division Multiplexing) system. Then, we analyzed the performance of OFDM system through simulation over the JTC (Joint Technical Committee) realistic channel model. In addition we carried out the performance by using pilot training symbol, which is one of the channel estimation methods, over the same channel environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.6A
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• pp.1099-1106
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• 2001

본 논문에서는 IEEE 802.11a 표준안으로 확정된 OFDM(Orthogonal Frequency Division Multiplexing) 방식을 적용한 고속 무선 LAN의 최적 시스템을 설계하기 위하여 실내 채널 특성들을 분석하였다. 통계적 채널 모델링 및 JTC(Joint Technical Committee) 모델에서의 실내 및 실외 환경을 선택하여 채널에 따른 고속 무선 LAN 시스템을 모의 실험하였다. 또한 채널에 의한 열화를 보상하기 위하여 무선 LAN 표준안에 따른 긴 훈련 신호를 이용한 채널 등화기법인 LS(Least Square) 방식과 LMMSE(Linear Minimum Mean Square Error) 방식을 비교 분석하였다. LS 기법과 본 논문에서 제시한 LS 방식으로 채널의 지연 확산 rms(root mean square) 값을 추정한 후 LMMSE 기법을 사용한 경우의 차이점을 고찰하였다. 이러한 LMMSE 기법을 채택할 경우 LS 기법에 비해 실외환경과 같은 열악한 채널환경 하에서도 시스템 성능에 상당한 개선효과가 나타남을 확인할 수 있었다.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.465-470
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• 2002

Construction of Yamanashi Maglev Test Line in Japan was proceeded based on "superconducting maglev Yamanshi Testline plan" approved by Ministry of Transport Government of Japan in 1990, which was performed by Yamanashi Maglev Test Line construction project team organized by personnel of Japan Railway Construction Public Corporation, RTRI and Central Japan Railway Company, and overall adjustment test was performed. Yamanashi Maglev experimental project team was organized, sponsored by RTRI and Central Japan Railway Company from April in 1997. Running test for the application was performed by this project team. Technical availability was proved by "superconducting maglev committee" of Ministry of Transport Government in March, 2000. In this paper, train radio system by LCX and by millimeter wave will be reviewed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.192-197
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• 2003

Initial hull form of 3 G/T and $20{\sim}25$ knots class coastal leisure boat is newly developed. The performances, which are resistance, trim and sinkage, are investigated at high speed circulating water channel (CWC). Wave patterns are observed together to make clear the relation between the resistance performance and the wave characteristics.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.457-458
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• 2013

전 세계 1내지 2 퍼센트에 해당하는 여성선원 중 상선에 종사하는 여성해기사는 그 중 6 퍼센트에 해당한다. 해운 산업의 구성 인력 중 소수라고 할 수 있으나 여성의 원활한 해상 진출을 위해 국제해사기구를 비롯하여 정부, 교육단체, 노조 및 해운선사들의 지원과 관심이 필요한 시점이다. 이에 그 동안 국제해사기구를 비롯하여 여성해기사를 위한 현존 지원 정책을 살펴 보고, 향후 여성해기사의 역량강화 및 해상진출을 위한 제도적, 정책적 요소들을 식별하였다.

• Journal of the Korea Computer Industry Society
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• v.9 no.2
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• pp.77-82
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• 2008

The diversity reception and the equal gain combining technique are applied to the compensation of the distortion of channel, which occurs in transmission of data at rapid speed. DSSS BPSK system which has the receiving structure with the compensation algorithm is formed on the diversity branch, and the characteristics of the system are evaluated at the view point of the average bit error rate due to the SNR. In addition, the multi-tap update algorithm which is superior for the data compensation is suggested. Moreover, using the American Joint Technical Committee PCS RF channel characterization and system deployment model standard, the suggested multi-tap update algorithm is compared and analyzed with the view-point of the average bit error rate and convergence speed for evaluating the realistic efficiency of the system.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.1 no.1
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• pp.51-61
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• 1995

This paper is discussed on the prospects of packaging industry and technologies of Japan for comming 21th century. It is clear that packaging industry depends on living style and social mechanizms. A trends of numerical consumption, amounts of money and composisition of packaging materials are one of a measure of development of packaging industry. Total consumption of packaging materials in Japan of 1965, 1980 and 1993 were $6,344.5{\times}10^3,\;15,898.7{\times}10^3\;and\;21,603.3{\times}10^3$ tons respectively and also, shipping money of packaging materials were $7,073{\times}10^{11},\;45,421{\times}10^{11}\;and\;63,902{\times}10^{11}$ yen, respectively. It is estimated from these data that the packaging industry is also increasing in future according of GNP of country. Compositions of packaging materials from 1965 to 1993, however, are somewhat changing according to development of new materials or social conditions such as platics packaging or wooden packaging materials. Technical forcasts of packaging industry are shown from view point of national living style, energy and resorces as well as environment of world based on forcasting committee of pulp & paper in Japan, report of research committee for the 21th packaging in JPI and materials of symposium in Kanagawa University in this paper. As a my conclusion, many functional packaging materials shall be developed in the future and accordingly Life Cycle Assesment plays a important role of packaging fields. Furthermore, I am estimating in future the new cellulosic materials such as nonwood fiber resources instead of paper, board, wooden containers and a part of plastic packaging materials shall be developed. This paper is constructed by three items as follow:

• The Journal of Engineering Geology
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• v.32 no.3
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• pp.363-376
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• 2022

An area under construction for a living facility collapsed around 12:48 KST on 13 January 2021 in Sa-dong, Ansan-si, Gyeonggi-do. There were no casualties due to the rapid evacuation measure, but part of the temporary retaining facility collapsed, and several cracks occurred in the adjacent road on the south side. This study used the potential of synthetic aperture radar (SAR) satellite for surface property changes that lies in backscattering characteristic to map the collapsed structure. The interferometric SAR technique can make a direct measurement of the decorrelation among different acquisition dates by integrating both amplitude and phase information. The damage proxy map (DPM) technique has been employed using four high-resolution Constellation of Small Satellites for Mediterranean basin Observation (COSMO-SkyMed) data spanning from 2020 to 2021 during ascending observation to analyze the collapse of the construction. DPM relies on the difference of pre- and co-event interferometric coherences to depict anomalous changes that indicate collapsed structure in the study area. The DPMs were displayed in a color scale that indicates an increasingly more significant ground surface change in the area covered by the pixels, depicting the collapsed structure. Therefore, the DPM technique with SAR data can be used for damage assessment with accurate and comprehensive detection after an event. In addition, we classify the amplitude information using support vector machine (SVM) and maximum likelihood classification algorithms. An investigation committee was formed to determine the cause of the collapse of the retaining wall and to suggest technical and institutional measures and alternatives to prevent similar incidents from reoccurring. The report from the committee revealed that the incident was caused by a combination of factors that were not carried out properly.

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.1-12
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• 2008

International Standardization in all technical area is gaining its momentum as its impact and implication over global trade is directly linked. The worldwide competition to secure a dominant position in the standardization process is ever growing over the years. In 2005, the International Technical Committee on Nuclear Instrumentation, which is a subunit of International Electro-technical Commission (IEC), was held in Korea under the auspices of MOST (Ministry of Science and Technology). Korea has adopted its Rule and Regulation as the National Standard. As a part of a link to National Mid-and Long-term Atomic Energy R&D Program of MOST, the technical development of a performance test for the radiation monitors was carried out under mechanical environment and electromagnetic immunity conditions. The characteristics of the radiation fields were also evaluated under the conditions and introduced to a techniques of performance test for the radiation protection instrumentation adopted IEC61526 standards and it's results was analyzed. We would like to share the experience gained in these efforts, failure as well as success, and to discuss the problems encountered and serious consideration to be taken into account in the future endeavor.

• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.29-34
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• 2006

This study aims to provide divers with improved sqfe diving practices by analyzing reports on scuba diving casualties that recently (from 1997-2003) occurred in Korea, Japan and USA The result of this study may contribute to reduce the diving accident. The data were collected through the diving accident reports of various sources, which include reports of the KUA (Korea Underwater Association) technical committee, the accident statistical data of Korea Coast Guard, articles of domestic and foreign scuba diving magazines, accident reports of various newspapers, annual reports on decompression illness and diving fatalities by DAN (Diver Alert Network), diving accident data reported to local and national seminars, and medical treatment data of diving accident. The analysis focused on the diving casualties and the result showed that the casualty rate in Korea was 2.8 and 2.2 times higher than those in Japan and USA, respectively.