• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
• /
• pp.203-207
• /
• 2003

Due to the inherent nature of the low flying UAV, obstacle detection is a fundamental requirement in the flight path to avoid the collision from obstacles as well as manned aircraft. In this paper, a preliminary sensor requirements of an obstacle detection system for UAV in low-altitude flight are analyzed, and the automated obstacle detection sensor system is proposed assessing both passive and active sensors such as EO camera, IR, Laser radar, microwave and millimeter radar. In addition, TCAS (Traffic Alert and Collision Avoidance System) are reviewed for the collision avoidance of the manned aircraft system. It is suggested that small-sized radar sensor is the best candidate for the smart UAV because an active radar can provide the real-time informations on range and range rate in the all-weather environment. However, an important constraints on small UAV should be resolved in terms of accommodation of the mass, volume, and power allocated in the payload of the UAV system design requirements.

• International Journal of Aeronautical and Space Sciences
• /
• 제6권2호
• /
• pp.97-109
• /
• 2005

In this paper, the critical requirement for obstacle awareness and avoidance is assessed with the compliance of the equivalent level of safety regulation, and then the collision avoidance sensor system is presented with the key design parameters for the requirement of the smart unmanned aerial vehicle in low-altitude flight. Based on the assessment of various sensors, small-sized radar sensor is selected for the suitable candidate due to the real-time range and range-rate acquisition capability of the stationary and moving aircraft even under all-weather environments. Through the performance analysis for the system requirement, the conceptual design result of radar sensor model is proposed with the range detection probability and collision avoidance mode is established based on the time-to-collision, which is analyzed by collision scenario.

• 한국항해항만학회지
• /
• 제32권7호
• /
• pp.529-535
• /
• 2008

As a method to reduce collision accidents of ships at sea, this paper suggests an expert system for collision avoidance and navigation (hereafter "ESCAN"). The ESCAN is designed and developed by using the theory and technology of expert system and based on the information provided by AIS and RADAR/ARPA system. In this paper the ESCAN is composed of four(4) components; Facts/Data Base in charge of preserving data from navigational equipment, Knowledge Base storing production rules of the ESCAN, Inference Engine deciding which rules are satisfied by facts or objects, User System Interface for communication between users and ESCAN. The ESCAN has the function of real--time analysis and judgment of various encountering situations between own ship and targets, and is to provide navigators with appropriate plans of collision avoidance and additional advice and recommendation This paper, as a basic study, is to introduce the basic design and function of ESCAN.

• 한국전자파학회논문지
• /
• 제20권8호
• /
• pp.784-790
• /
• 2009

전방 감시 차량용 레이다에서 표적 거리와 속도 정보를 얻기 위해서는 일반적으로 주파수 변조된 연속파형(FMCW)이나 펄스 도플러(PD) 파형을 사용하고 있다. 그러나 고해상도의 표적 정보를 얻기 위해서는 펄스 폭이 매우 좁고 넓은 대역폭을 사용하여야 하므로 상대적으로 높은 첨두 전력이 필요하고 고속의 디지털 변환 처리속도가 요구된다. 본 논문에서는 계단 주파수 변조된 펄스 도들러 파형을 이용하여 고해상도의 표적 정보를 획득할 수 있는 SFPD(Stepped-frequency Pulsed-Doppler) 처리 기법을 제시한다. 제안된 SFPD 기법은 시뮬레이션을 통하여 기존의 FMCW 및 펄스 도플러 파형 방식과 비교 분석하였다. 본 기법은 필요에 따라서 거리 및 도플러 해상도를 가변할 수 있는 장점이 있기 때문에 이론적으로 고해상도의 표적 영상 형성이 가능하여 향후 정밀한 차량 충돌 방지를 위한 표적 식별에 활용할 수 있을 것으로 기대한다.

• 대한전자공학회논문지TC
• /
• 제43권9호
• /
• pp.1-5
• /
• 2006

본 논문에서는 ITS 기반의 기본 센서인 차량 충돌방지 레이더의 허상으로 인한 오신호 또는 시스템간의 상호 간섭을 방지하기 위하여 전파흡수체를 설계 및 제작하였다. 먼저 도전손실 재료인 카본과 지지재인 CPE를 이용하여 조성비별 전파흡수체 샘플을 제작하고, 측정데이터로부터 최적의 조성비가 카본:CPE=20:80 wt% 임을 확인하였다. 그리고 이 샘플로부터 재료정수인 복소비유전율을 계산하여 시뮬레이션을 하였으며, 시뮬레이션 결과를 토대로 전파흡수체를 실제작하여 전파흡수능을 비교 분석한 결과 시뮬레이션값과 측정값이 잘 일치하였다. 결과적으로 조성비 카본:CPE=20:80 wt%로 전파흡수체 두께 2 mm 주파수 범위 $76{\sim}77$ GHz에서 전파흡수능 20 dB 이상으로 전파흡수체를 개발하였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2007년도 하계종합학술대회 논문집
• /
• pp.107-108
• /
• 2007

In this paper, the EM wave absorbers were designed and fabricated for collision-avoidance radars using Carbon of a dielectric material and Permalloy of a magnetic material with CPE, because radar system has some problems including false image and system-to-system interference. We fabricated some samples in different composition ratio of Carbon and Permalloy, and defined that optimum composition ratios of Carbon and Permalloy with CPE were Carbon:CPE=20:80 wt% and Permalloy:CPE=70:30 wt%. And absorption abilities at different thicknesses of the EM wave absorbers were simulated using the material properties. The EM wave absorbers were manufactured based on the simulated design. Simulated and measured results agree very well.

• 대한인간공학회지
• /
• 제36권5호
• /
• pp.525-533
• /
• 2017

Objective: The aim of this study is to investigate maritime officers' strategies to avoid the ship collision in crossing situations. Background: In a situation where there is a risk of collision between two ships, maritime officers can change the direction and speed of the own-ship to avoid the collision. They have four options to select; adjusting the speed only, the direction only, both the speed and direction at the same time and no action. Research questions were whether the strategy they are using differs according to the shipboard experience of maritime officers and the representation method of ARPA (automatic radar plotting aid) - radar graphic information. Method: Participants were 12. Six of them had more than 3 years of onboard experience, while the others were 4th grade students at Korea Maritime and Ocean University. For each participant, 32 ship encounter situations were provided with ARPA-radar information. 16 situations were presented by the north-up display and 16 situations were presented by the track-up display. Participants were asked to decide how to move the own-ship to avoid the ship collision for each case. Results: Most participants attempted to avoid the collision by adjusting the direction of the ship, representing an average of 22.4 times in 32 judgment trials (about 70%). Participants who did not have experience on board were more likely to control speed and direction at the same time than participants with onboard experience. Participants with onboard experience were more likely to control the direction of the ship only. On the other hand, although the same ARPA Information was provided to the participants, the participants in many cases made different judgments depending on the method of information representation; track-up display and north-up display. It was only 25% that the participants made the same judgment under the same collision situations. Participants with onboard experience did make the same judgment more than participants with no onboard experience. Conclusion: In marine collision situations, maritime officers tend to avoid collisions by adjusting only the direction of their ships, and this tendency is more pronounced among maritime officers with onboard experience. The effect of the method of information representation on their judgment was not significant. Application: The results of this research might help to train maritime officers for safe navigation and to design a collision avoidance support system.

• 수산해양기술연구
• /
• 제50권1호
• /
• pp.21-29
• /
• 2014

The dynamic information of radar and automatic identification system (AIS) for targets obtained from the traffic vessels operating in the north outer harbor and surrounding waters of Busan port, Korea. The target information was analyzed to investigate the potential collision risk resulting from the invalid true heading (HDT) information of AIS and the integration ambiguity in the graphic presentation of both tracked data sets for two systems. An integrated display system (IDS) for supporting the navigator of offshore fishing vessels was also developed to find possible maneuvering solutions for collision avoidance by comparing radar data with AIS data in real-time at sea. Consequently, the multiple functions of IDS can provide additional information that is potentially valuable for taking action to avoid the collision in offshore fishing vessels. However, the integration criteria of radar and AIS targets in the IDS must be carefully established to eliminate the fusion ambiguity in the graphic presentation of both AIS and radar symbols such as the one or two physical targets which are very close to each other.

• 한국항공운항학회:학술대회논문집
• /
• 한국항공운항학회 2004년도 추계학술발표대회 논문집
• /
• pp.258-261
• /
• 2004

• 대한조선학회논문집
• /
• 제60권3호
• /
• pp.155-164
• /
• 2023

About 75% of vessel collision accidents are caused by human error, which causes enormous economic loss, environmental pollution, and human casualties, thus research on automatic collision avoidance of vessels is being actively conducted. In addition, vessels must comply with the COLREGs rules stipulated by IMO when performing collision avoidance with other vessels in motion. In this study, the collision risk was calculated by estimating the position and velocity of other vessels through the Probabilistic Data Association Filter (PDAF) algorithm based on RADAR sensor data. When a collision risk is detected, we propose an event-triggered Nonlinear Model Predict Control (NMPC) algorithm that geometrically creates waypoints that satisfy COLREGs and follows them. To verify the proposed algorithm, simulations through MATLAB are performed.