• 대한원격탐사학회지
• /
• 제40권2호
• /
• pp.219-228
• /
• 2024

Vessels can operate with their Automatic Identification System (AIS) turned off, prompting the development of strategies to identify them. Among these, utilizing satellites to collect radio frequency (RF) data in the absence of AIS has emerged as the most effective and practical approach. The purpose of this study is to develop a matching algorithm for RF with AIS data and find the RF's applicability to classify a suspected ship. Thus, a matching procedure utilizing three RF datasets and AIS data was employed to identify ships in the Yellow Sea and the Korea Strait. The matching procedure was conducted based on the proximity to AIS points, ensuring accuracy through various distance-based sections, including 2 km, 3 km, and 6 km from the AIS-based estimated points. Within the RF coverage, the matching results from the first RF dataset and AIS data identified a total of 798 ships, with an overall matching rate of 78%. In the cases of the second and third RF datasets, 803 and 825 ships were matched, resulting in an overall matching rate of 84.3% and 74.5%, respectively. The observed results were partially influenced by differences in RF and AIS coverage. Within the overlapped region of RF and AIS data, the matching rate ranged from 80.2% to 98.7%, with an average of 89.3%, with no duplicate matches to the same ship.

• 한국항해항만학회지
• /
• 제37권5호
• /
• pp.447-452
• /
• 2013

해상교통관제시스템(VTS)은 선박의 위치, 속도, 침로 등 해상 교통 정보를 획득하기 위하여 다수의 해상감시레이더를 주요 센서로 이용하고 있으며, 거리 및 방위각 바이어스와 같은 2차원 해상감시레이더의 시스템 오차는 레이더 영상 및 표적 추적정보의 정확도를 크게 저하시킬 수 있다. 따라서 해상교통관제시스템에서 정확한 표적정보를 제공하기 위하여 레이더의 시스템 오차는 정밀하게 보정되어야 한다. 본 논문에서는 VTS 관제영역에 설치된 항로표지의 위치정보를 이용하여 2차원 해상감시레이더의 거리 및 방위각 오차를 보정하기 위한 방법을 제안한다. 2차원 레이더 측정값의 표준오차 모델과 항로표지 위치정보로부터 측정 잔차 모델을 유도하고, 레이더 시스템 오차를 추정하기 위한 선형 칼만필터를 설계한다. Monte-Carlo 모의실험을 통하여 제안한 방법을 검증하고, 항로표지 정보의 개수에 따른 레이더 시스템 오차 추정의 수렴 특성 및 정확도를 분석한다.

• 한국지리정보학회지
• /
• 제27권2호
• /
• pp.19-33
• /
• 2024

방범용 CCTV는 지속적으로 증설되고 있으나 설치 위치 결정에 대한 가이드라인의 부재로 범죄 발생 다발지역과 무관한 위치에 CCTV가 설치되는 경우가 많다. 이에 본 연구에서는 도시공간빅데이터를 활용하여 CCTV 우선설치지수를 개발하고, 사례지역에 시범 적용하여 적용 가능성을 타진하였다. CCTV 우선설치지수는 범죄취약지수와 감시취약지수로 구성하였으며, 각각 머신러닝 알고리즘을 통해 예측한 그리드별 범죄발생건수, 가시권 분석을 통해 산출한 그리드별 감시불가면적의 비율을 활용하여 산출하였다. 지수를 시범지역에 적용한 결과 CCTV 가시권 분석에 Viewshed 기능을 활용함으로써 기존 버퍼 기능 활용 시 감시면적이 과대 추정되었던 문제를 해결할 수 있었다. 또한 해당 지수를 적용하여 CCTV 설치 위치를 결정할 경우, 감시면적을 효율적으로 개선 가능하다. 본 연구의 CCTV 위치 결정 프로세스에 따라 사례지역에 신규 CCTV를 추가 설치할 경우, 도로면적 대비 감시면적이 43.25%에서 83.73%로 증가하였다. 따라서, CCTV 우선설치지수는 스마트안전도시 조성을 위한 효과적인 의사결정 도구로 활용될 수 있을 것이다.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 2008년도 한국컴퓨터종합학술대회논문집 Vol.35 No.1 (A)
• /
• pp.261-262
• /
• 2008

Due to technological advances, the manufacturing of small and low cost of sensors becomes technically and economically feasible. In recent years, an increasing interest in using Wireless Sensor Network (WSN) in various applications, including large scale environment monitoring, battle field surveillance, security management and location tracking. In these applications, hundreds of sensor nodes are left to be unattended to report monitored data to users. Since sensor nodes are placed randomly and sometimes are deployed in underwater. It is impossible to replace batteries often when batteries run out. Therefore, reducing energy consumption is the most important design consideration for sensor networks.

• 대한원격탐사학회지
• /
• 제22권3호
• /
• pp.229-234
• /
• 2006

In tactical theater, it is crucial to detect ground moving targets and to locate them precisely. This problem can be resolved by using SAR (Synthetic Aperture Radar) sensors providing GMTI (Ground Moving Target Indication) capability. In general, to implement a robust GMTI sensor is not simple because of the strong competitions between target signals and clutter signals from the ground, and low speed of moving targets. Contrary to the case that a delay canceller is mostly suitable for ground surveillance radars, DPCA (Displaced Phase Centered Antenna) or STAP (Space Time Adaptive Processing) techniques have been widely adapted for GMTI function of modern airborne radars. In this paper, a new scheme of DPCA using two passive antennas with vertical separation is proposed, which also provides good clutter cancellation performance. The proposed scheme realizes full azimuth coverage for DPCA operation on an airborne platform, which is impossible with classical DPCA configuration. Simulations using various conditions have been performed to validate the proposed scheme, and the results are acceptable.

• 전자통신동향분석
• /
• 제37권1호
• /
• pp.1-9
• /
• 2022

With the development of artificial intelligence, many studies have focused on evaluating abnormal situations by using various sensors, as industries try to automate some of the surveillance and security tasks traditionally performed by humans. In particular, mobile robots using multimodal sensors are being used for pilot operations aimed at helping security robots cope with various outdoor situations. Multiagent systems, which combine fixed and mobile systems, can provide more efficient coverage (than that provided by other systems), but network bottlenecks resulting from increased data processing and communication are encountered. In this report, we will examine recent trends in object recognition and abnormal-situation determination in various changing outdoor security robot environments, and describe an outdoor security robot platform that operates as a multiagent equipped with a multimodal sensor.

• 수산해양기술연구
• /
• 제45권3호
• /
• pp.177-187
• /
• 2009

This paper describes a automatic video surveillance system(AVSS) with long range and 360$^{\circ}$ coverage that is automatically rotated in an elevation over azimuth mode in response to the TTM(tracked target message) signal of vessels tracked by ARPA(automatic radar plotting aids) radar. This AVSS that is a video security and tracking system supported by ARPA radar, CCTV(closed-circuit television) camera system and other sensors to automatically identify and track, detect the potential dangerous situations such as collision accidents at sea and berthing/deberthing accidents in harbor, can be used in monitoring the illegal fishing vessels in inshore and offshore fishing ground, and in more improving the security and safety of domestic fishing vessels in EEZ(exclusive economic zone) area. The movement of the target vessel chosen by the ARPA radar operator in the AVSS can be automatically tracked by a CCTV camera system interfaced to the ECDIS(electronic chart display and information system) with the special functions such as graphic presentation of CCTV image, camera position, camera azimuth and angle of view on the ENC, automatic and manual controls of pan and tilt angles for CCTV system, and the capability that can replay and record continuously all information of a selected target. The test results showed that the AVSS developed experimentally in this study can be used as an extra navigation aid for the operator on the bridge under the confusing traffic situations, to improve the detection efficiency of small targets in sea clutter, to enhance greatly an operator s ability to identify visually vessels tracked by ARPA radar and to provide a recorded history for reference or evidentiary purposes in EEZ area.

• Asian Pacific Journal of Cancer Prevention
• /
• 제14권5호
• /
• pp.3237-3241
• /
• 2013

Background: Under-ascertainment and over-ascertainment are common phenomena in surveillance and registry systems of health-related events. Capture-recapture is one of the methods which is applied to determine the sensitivity of surveillance or registry systems to recognize cancer cases. This study aimed to estimate the number of cancers using data available both in the Cancer Registry Center of Northwestern Iran and in the Population-based Cancer Registry Center of Iran. Material and Methods: The studied population consisted of all cancerous cases in the northwest of Iran from 2008 to 2010. All data were extracted from two resources and entered into Microsoft Excel software. After removing common and repeat cases the data were statistically analyzed using a capture-recapture studies' specific software "CARE 1.4". Estimations were calculated by Chapman and Petersen methods with the approximate confidence interval of 95%. Results: From 2008 to 2010, the number of all cancer cases was estimated to be 21,652 (CI 95%: 19,863-22,101). Sensitivity rate of all cancer cases was 83.9% and that of Population-based Cancer Registry Center of Iran was 52%. It was 93.1% considering both resources. Conclusion: Using two resources and the capture-recapture method rather than a single resource may be a more reliable method to estimate the number of cancer cases.

• 로봇학회논문지
• /
• 제18권1호
• /
• pp.1-9
• /
• 2023

This paper presents an optimal path planning strategy for aerial searching and surveying of a user-designated area using multiple Unmanned Aerial Vehicles (UAVs). The method is designed to deal with a single unseparated polygonal area, regardless of polygonal convexity. By defining the search area into a set of grids, the algorithm enables UAVs to completely search without leaving unsearched space. The presented strategy consists of two main algorithmic steps: cellular decomposition and path planning stages. The cellular decomposition method divides the area to designate a conflict-free subsearch-space to an individual UAV, while accounting the assigned flight velocity, take-off and landing positions. Then, the path planning strategy forms paths based on every point located in end of each grid row. The first waypoint is chosen as the closest point from the vehicle-starting position, and it recursively updates the nearest endpoint set to generate the shortest path. The path planning policy produces four path candidates by alternating the starting point (left or right edge), and the travel direction (vertical or horizontal). The optimal-selection policy is enforced to maximize the search efficiency, which is time dependent; the policy imposes the total path-length and turning number criteria per candidate. The results demonstrate that the proposed cellular decomposition method improves the search-time efficiency. In addition, the candidate selection enhances the algorithmic efficacy toward further mission time-duration reduction. The method shows robustness against both convex and non-convex shaped search area.

• Advances in aircraft and spacecraft science
• /
• 제2권1호
• /
• pp.95-108
• /
• 2015

Automatic Dependent Surveillance Broadcast (ADS-B) is quickly being adopted by aviation safety authorities around the world as the standard for aircraft tracking. The technology provides the opportunity for live tracking of aircraft positions within range of an ADS-B receiver stations. Currently these receiver stations are bound by land and local infrastructural constraints. As such there is little to no coverage over oceans and poles, over which many commercial flights routinely travel. A low cost space based ADS-B receiving system is proposed as a constellation of small satellites. The possibility for a link between aircraft and satellite is dependent primarily on proximity. Calculating the likelihood of a link between two moving targets when considering with the non-periodic and non-uniform nature of actual aircraft flight-paths is non-trivial. This analysis of the link likelihood and the performance of the tracking ability of the satellite constellation has been carried out by a direct simulation of satellites and aircraft. Parameters defining the constellation (satellite numbers, orbit size and shape, orbit configuration) were varied between reasonable limits. The recent MH370 disappearance was simulated and potential tracking and coverage was analysed using an example constellation. The trend of more satellites at a higher altitude inclined at 60 degrees was found to be the optimal solution.