• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.7
• /
• pp.69-75
• /
• 2004

An avoidance/guidance problem of an aircraft against moving obstacle is considered in two dimensional space. The aircraft is modelled as a point mass flying with constant speed. The lateral acceleration is assumed the control input. Artificial potential functions are applied to the terminal point and moving obstacles in order that repulsive forces and an attractive force are produced by the obstacles and the terminal point respectively. A real time guidance/avoidance law is proposed by using the potential forces and relative velocity. The guidance law for a logarithm potential function results the well-known proportional navigation law. The avoidance control command is inverse proportional to the time-to-go to the obstacle and turns the aircraft toward the negative direction of the line-of-sight change. The performance of the proposed guidance/avoidance law is verified with simulations.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.1
• /
• pp.127-132
• /
• 2018

One of the key issues in the Unmanned Aerial Vehicle (: UAV) technology is the collision avoidance. Specifically, the collision avoidance among multiple UAVs is critical to expand UAV applications to civil sector where large number of UAVs could be operated in the limited space. In this paper, we introduce a collision avoidance scheme based on Flying Ad Hoc Network (: FANET). The proposed scheme adopts collision avoidance mechanism used in wireless data communication networks. Using this scheme UAVs can not only communicate conventional user information, but also share flight information to avoid collision.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.23-29
• /
• 2006

From a point of view of suggesting the method to avoid ship's collision, the speed of ships has to be considered sufficiently according to encounter angle of ships. But with respect to the establishment of Safe-Guard Ring of Ship Collision Avoidance Support Model in Close Quarters Situation that had been newly studied to avoid ship's collision, the ratio of own ship' speed to a target ship's speed was limited to about less than 1.7. Therefore in this paper, as doing a study concerned with the establishment of Safe-Guard Ring reflected the encounter angle and the speed of ships, we will propose the new model of ship collision avoidance for safe maneuver of ship's collision avoidance.

• 한국벤처창업학회:학술대회논문집
• /
• 2023.11a
• /
• pp.85-89
• /
• 2023

최근 급변하는 세계 경제 환경에서 창업기업은 혁신, 고용 및 경제 활력의 핵심 동력으로 등장했다. 그러나 초기 창업 기업이 성장하는 여정에는 많은 어려움이 따르며, 이 과정에서 엔젤투자자의 역할이 필수적이다. 초기 창업 시장의 촉매제 역할을 하는 엔젤투자자는 필요한 자본을 제공할 뿐만 아니라 경영 노하우 및 네트워크를 통해 창업기업이 성공할 수 있도록 지원한다. 그러나 최근 데이터에 따르면 신생 기업 중 엔젤 투자의 혜택을 받는 기업은 1.4%에 불과한 것으로 나타나 창업기업의 잠재력과 지원 사이에는 분명한 공백이 존재한다. 이 연구는 지속가능한 경제 성장을 위해 창업 생태계의 중요한 요소인 엔젤투자자의 위험회피 성향을 이해함으로써 이들의 투자 행동, 의사결정 프로세스에 대한 통찰력을 얻을 수 있다. 위험회피가 엔젤투자에 미치는 영향을 알아보고 엔젤투자가 활성화 될 수 있는 방법을 제안하고자 한다. 본 연구를 통해 위험회피 성향이 엔젤투자에 대한 관심도와 실제 투자 활동 간의 관계를 추정해보고자 한다. 위험회피 성향이 엔젤투자자에 어떻게 영향을 미치는지 탐색하는 것에 중점을 두고, 엔젤투자자의 행동과 관심사에 영향을 미치는 다양한 요인들을 포함하여 진행한다. 연구 표본은 서울 및 경기 지역의 일반 성인과 엔젤투자자로 설문조사를 통해 필요한 데이터를 수집한다. 이 연구는 위험회피 성향이 엔젤투자 결정에 어떻게 반영되는지에 대한 깊은 이해를 제공하고, 엔젤투자 활성화를 위한 정책 및 전략을 수립하는데 중요한 통찰력을 제공할 것이다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2004.04a
• /
• pp.121-124
• /
• 2004

본 본문은 하이퍼카오스, 로렌츠, 해밀톤 방정식과 같은 여러 종류의 카오스 회로를 이동 로봇에 내장하여 카오스 이동 로봇을 구성하고 이 카오스 이동 로봇이 어느 임의 평면을 카오스 궤적을 가지고 탐색하다가 장애물을 만나거나 근접하게 되면 장애물을 회피하는 방법을 제시하고 그 결과를 검증하였다. 목표물 회피에서는 장애물 탐사와 유사한 카오스 궤적을 가지고 회피하도록 하는 알고리즘을 개발하고 그 결과를 검증하였으며 이에 대한 타당성을 확인하였다.

• Management & Information Systems Review
• /
• v.32 no.5
• /
• pp.261-285
• /
• 2013

In this paper, examined relationship between Earnings Management and Conservatism. For analysis of this purpose, we applied the Earnings Loss Avoidance Firms and Big-bath Firms. The results are as follows. First, conservative of Earnings Loss Avoidance Firms(sample I, II) is lower than the controlled companies. And Big-bath firms(sample III, IV) is higher than the controlled companies. This is a negative relationship between conservative and earning management. These results are consistent with previous research results. Second, When analyzing the Earnings Loss Avoidance Firms(sample I, II), Results are presented that conservative and earning management related to positive. These results reflect the company to Investors' demand for conservatism.

• Journal of Advanced Navigation Technology
• /
• v.26 no.6
• /
• pp.427-433
• /
• 2022

Obstacle detection, collision recognition, and avoidance technologies are required the collision avoidance technology for UAVs. In this paper, considering collinear multiple static obstacle, we propose an obstacle detection algorithm using LiDAR and a collision recognition and avoidance algorithm based on CPA. Preprocessing is performed to remove the ground from the LiDAR measurement data before obstacle detection. And we detect and classify obstacles in the preprocessed data using the K-means clustering algorithm. Also, we estimate the absolute positions of detected obstacles using relative navigation and correct the estimated positions using a low-pass filter. For collision avoidance with the detected multiple static obstacle, we use a collision recognition and avoidance algorithm based on CPA. Information of obstacles to be avoided is updated using distance between each obstacle, and collision recognition and avoidance are performed through the updated obstacles information. Finally, through obstacle location estimation, collision recognition, and collision avoidance result analysis in the Gazebo simulation environment, we verified that collision avoidance is performed successfully.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2004.11a
• /
• pp.89-94
• /
• 2004

Up to now a lot of the study on ship collision avoidance systems has proceeded actively. However the frequency of ship collision accidents didn't decreased. If there is collision risk in close quarters situation none the less manouvering ship for collision avoidance according to the system, only use of TCPA and DCPA as input factor for collision risk decision is not useful to avoiding collision action. For the recent 5 years by the analysis of first observation distance about approaching ship in domestic collision accidents, nearly $45\%$ of accidents is close first observation less than 2 miles. Therefor it is essential part for safety navigations to study for collision avoidance action in close encounter. In this paper, as foundation study of supporting collision avoidance manoeuvring for navigators, we proposed ship collision avoidance support model in close quarters situation through analysis of collision accidents for effective getting rid of the causes.

• Proceedings of KOSOMES biannual meeting
• /
• 2005.11a
• /
• pp.15-20
• /
• 2005

Recently, ship collision accidents account for $20\%\∼30\%$ of domestic marine accidents, also have increased continually. In this paper, therefore we propose the development of Ship Collision Avoidance Support program for decreasing ship collision accidents. This program has been developed on the basis of CCAS-Model. A CCAS-Model has ship's maneuvering performance and has studied for the propose of supporting to avoid ship collision in close quarters. Besides, the program will effectively support maneuvering for collision avoidance through displaying the feasible area and the method of collision avoidance using own ship's turning characteristic about action of target ship's keeping course and velocity in various encounter.

• Journal of Navigation and Port Research
• /
• v.28 no.10 s.96
• /
• pp.827-832
• /
• 2004

Up to now a lot of the study on ship collision avoidance systems have proceeded actively. However the rate of ship collision accidents hasn't decreased yet. If there is collision risk in close quarters situation in spite of maneuvering ship for collision avoidance according to the system, only use of TCP A and DCP A as input factor for collision risk decision is not useful to avoiding collision action. For the recent 5 years by the analysis of first observation distance about approaching ship in domestic collision accidents, nearly $45\%$ of accidents is close first observation less than 2 miles. Therefore it is essential part for safety navigations to study for collision avoidance action in close encounter. In this paper, as a fundamental study of supporting collision avoidance maneuvering for navigators, we proposed ship collision avoidance support model in close quarters situation through analysis qf collision accidents to effectively get rid of the causes.