• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.488-490
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• 2013

2013년 11월 27일 구성된 제주 민군복합형 관광미항 크루즈 선박조종 시뮬레이션 시현 TF팀은 2013. 1. 17~18일 한국해양과학기술원에서 3차원 다기능 선박조종시뮬레이터(Full Mission Ship-Handling Simulator)을 이용하여 도선사 4명이 주, 야간 및 입선, 출선자세 접안 16개 시나리오를 가지고 시뮬레이션을 실시하였으며, 평가 기법은 "해사안전법"의 해상교통안전진단 시행지침(국토해양부 고시 제2012-129호(2012.3.21.), 해상교통시스템 적정성 평가(선박조종시뮬레이션, 통항안전성 및 접 이안안전성 평가)를 준용하였다. 시뮬레이션 평가 결과 근접도에 따른 충돌[침범] 확률이 $10^{-4}$미만이고, 운항자[주관적] 평가의 결과가 평균 -2.0 이하로 해상교통환경 변화에 따른 통항안전성 및 접이안 안전성 확보가 가능하다고 평가되었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.323-325
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• 2012

SNS의 활용에 따라 대규모의 네트워크가 생성되고 있고, 네트워크에서 생성되는 커뮤니티의 구조를 파악하기 위한 많은 연구가 진행되고 있다. 파악된 커뮤니티를 통합하는 방안은 서로 다른 커뮤니티를 통합할 필요가 있을 때 활용된다. 본 연구에서는 파악된 2개의 커뮤니티를 하나의 커뮤니티로 만들기 위해 필요한 에지추가 방법을 연구한다. 파악된 커뮤니티를 통합하기 위해 각 커뮤니티를 연결하여야 하는데, 이 때 각 커뮤니티 내의 노드들에 대해 노드 근접도를 계산하여 커뮤니티의 중심을 찾는다. 중심에 가까운 노드들을 순차적으로 이용하여 커뮤니티가 통합될 때까지 에지를 생성하여 그래프에 추가한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.463-466
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• 2010

길이가 긴 질의에는 검색에 불필요한 단어가 포함되어 있어서 사용자가 원하지 않는 문서가 검색결과에 포함된다. 질의에서 불필요한 단어를 제거하고 핵심 단어만 선택한다면 검색에 효율을 높일 수 있다. 본 논문에서는 질의 조합을 기반한 클러스터를 이용해 핵심 단어를 찾고 핵심 단어와의 근접도를 이용해 상위 문서의 정확율을 향상시키는 기법을 제안한다. 실험은 뉴스 집합인 TREC AP 문서를 검색한 결과를 제안한 알고리즘으로 재순위화하여 초기 검색 결과의 상위 문서의 정확율을 비교함으로써 제안된 알고리즘의 유효성을 검증한다.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.53-54
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.164-165
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• 1999

• Journal of KIISE:Databases
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• v.32 no.4
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• pp.429-440
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• 2005

As rapid improvement in electronic technologies makes sensor hardware more powerful and capable, the application range of sensor networks Is getting to be broader. The main purpose of sensor networks is to monitor the phenomena in interesting regions (e.g., factory warehouses, disaster areas, wild fields, etc) and return required data. The k Nearest Neighbor (KNN) query that finds k objects which are geographically close to the given point is an Important application in sensor networks. However, most previous approaches are either seem to be impractical or are not energy-efficient in resource-limited sensor networks. In this paper. we propose an efficient KNN query processing method in sensor networks. In the proposed method, we dynamically increase searching boundary, if necessary, and traverse nodes inside the boundary until finding k nearest neighbors. Since only the representative sensor nodes are visited, our algorithm reduces a number of messages. We show thorough experiments that the proposed method performs better than the existing method in various network environments.

• The Korean Journal of Applied Statistics
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• v.26 no.5
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• pp.835-845
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• 2013

Travel-time is considered the most typical and preferred traffic information for intelligent transportation systems(ITS). This paper proposes a real-time travel-time prediction method for a national highway. In this paper, the K-nearest neighbor(KNN) method is used for travel time prediction. The KNN method (a nonparametric method) is appropriate for a real-time traffic management system because the method needs no additional assumptions or parameter calibration. The performances of various models are compared based on mean absolute percentage error(MAPE) and coefficient of variation(CV). In real application, the analysis of real traffic data collected from Korean national highways indicates that the proposed model outperforms other prediction models such as the historical average model and the Kalman filter model. It is expected to improve travel-time reliability by flexibly using travel-time from the proposed model with travel-time from the interval detectors.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1155-1164
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• 2011

In this paper, we proposed the transmit beam measurement method of active phased array antenna, which is installed in Korea's first developed naval medium range radar, using near-field measurement facility. The pulse-mode high power characteristics of active phased array antenna's trasmit-beam make it difficult to measure with general near-field measurement facilities where low power continuous RF signals are used. Thus, in this paper, the measurement method of active phased array antenna's transmit beam in conjunction with the near-field measurement facility, which is suitable for the high-power transmit beam measurement, and PNA-X network analyzer(Agilent Technologies), which can support pulse-mode measurement, was proposed and measured by near-field measurement techniques. And the EIRP(Effective Isotropic Radiated Power), the transmit characteristic of active phased array antenna, was measured by the near field measurement techniques and compared to numerical estimation which was nearly equal with small difference of 0.1 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.504-511
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• 2016

In this paper, the method is proposed that the equivalent result can be obtained by compensating the variation of gain and phase in the comparison with the result of near-field measurement which is obtained in the steady state, although the gain and phase variation of rx-channels occurred in the near-field rx-measurement of digital active phased array antenna. The proposed concept has the time section for monitoring the state of the rx-channels through the calibration path in the measurement timeline, and is the method for compensating the variation of state. For validating the proposed method, the fabricated X-band digital active phased array antenna and the planar near-field measurement facility is utilized. The proposed method is validated in the comparison with the compensated pattern which the unstable state of rx-channels is calibrated and the reference pattern obtained under the steady state of the rx-channels.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.8 no.2
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• pp.23-29
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• 1990

Non-metric camera is more profitable than metric camera for geometric analysis of small and elaborate structures, because focal length control of non-metric camera is flexible while generally metric camera has limited focal length. And if the problem of conventional method requiring much time and endeavor to measure three dimensional positions of control points will be solved effectively, it is possible to analyze very close-range photogrammetry more easily and quickly. The purposes of this study are to propose the efficiency of non-metric camera and to reduce difficulty of control survey sharply by introducing self-control survey method. For these, very close-range photographs of the small object were obtained by using non-metric camera calibrated for systematic errors and then bundle adjustment is used for analysis procedure. As a result, the superiority of non-metric camera in analyzing very close-range photographs and the application proptriety of self-control survey were proved, therefore it is expected to be able to apply to precise analysis of small structures or spearhead parts.