• 지식경영연구
• /
• 제23권3호
• /
• pp.45-64
• /
• 2022

소셜미디어의 사용이 증가함에 따라 소셜미디어 상에서의 온라인 범죄도 증가하고 있다. 본 연구에서는 다양한 범죄 중 온라인 상에서의 성희롱에 집중하여 소셜미디어 사용자들이 온라인 성희롱을 피하기 위하여 어떤 방식으로 소셜미디어를 사용하는지를 논의하고자 한다. 이를 위하여 기술 위협 회피 이론을 기반으로 회피 동기에 영향을 주는 요인을 밝혔다. 이때, 소셜미디어 상의 기술적인 기능을 회피동기를 기반하여 기능별로 반영하여 측정하였으며 환경적인 요인이 행동의 동기에 어떤 영향을 주는지 검증하기 위하여 소셜미디어 상의 성애화 정도의 영향을 검증하였다. 그 결과 소셜미디어 상에서 성애화 정도가 클수록 회피동기가 적어짐을 알 수 있었다. 이를 통해 소셜미디어 상에 성적인 분위기가 성희롱을 회피하는 것을 줄이므로 지속적인 플랫폼 상의 게시물에 대한 관리를 통하여 성희롱에 대한 소셜미디어 사용자들이 적절한 대응을 할 수 있고 플랫폼도 범죄가 줄어드는 분위기를 형성하는 것이 중요하다.

• 한국항해학회지
• /
• 제15권2호
• /
• pp.13-38
• /
• 1991

This paper intends to develop a Prototype Expert Collision Avoidance System by introducing expert system techniques into the decision block of anti-collision loop. The problem domain of this study is characterized and specified by combining the concepts of anti-collision loop and knowledge -based system for collision avoidance. Domain in knowledge which may originates from the appropriate sources such as the International Regulations for Preventing Collision at Sea 1972, Marine Traffic Laws, and many texts on the subject of anticollision navigation and good seamanship is acquired and formalized into the knowledge-base system using production rule. Finally, a Prototype Expert Collision Avoidance System is built by using the CLIPS, developed by AIS NASA written in and fully integrated with the C language, and some test-and-run results of the system are demonstrated and examined. The author considers the proposed system which is named PECAS to be meaningful as a test bed for a further refined Expert Collision Avoidance System on board the Automated Ship.

• 아동학회지
• /
• 제28권5호
• /
• pp.209-220
• /
• 2007

This study explored the effects of self efficacy, classroom contextual characteristics and help-avoidance attitudes on academic help-seeking behavior. Participants were 210 4th grade students. Data were analyzed by Pearson's correlation coefficient and multiple regression analysis through the SPSSWIN 12.0. Results showed that students' self efficacy, perception of teacher behavior and goal orientations were positively related to help-seeking behaviors. Help-avoidance attitudes were negatively related to help-seeking behaviors. Cognitive efficacy and social-emotional efficacy facilitated help-seeking behaviors. Help-seeking behaviors were influenced by teacher's supportive help and expectation. Mastery goal orientations and performance-approach goal orientations promoted help-seeking behaviors but performance-avoidance goal orientations impeded help-seeking behaviors. Autonomous intention attitudes expedited help-seeking behaviors but intention based on ability diminished help-seeking behaviors.

• 제어로봇시스템학회논문지
• /
• 제15권1호
• /
• pp.89-93
• /
• 2009

This paper deals with obstacle avoidance for unmanned vehicle using stereo system. The "DARPA Grand Challenge 2005" shows that the robot can move autonomously under given waypoint. RADAR, IMS (Inertial Measurement System), GPS, camera are used for autonomous navigation. In this paper, we focus on stereo system for autonomous navigation. Our approach is based on Singh et. al. [5]'s approach that is successfully used in an unmanned vehicle and a planetary robot. We propose an improved algorithm for obstacle avoidance by modifying the cost function of Singh et. al. [5]. Proposed algorithm gives more sharp contrast in choosing local path for obstacle avoidance and it is verified in experimental results.

• 한국전자통신학회논문지
• /
• 제7권1호
• /
• pp.187-194
• /
• 2012

본 논문에서는 이동 로봇이 자율주행을 하기 위해 사용되는 충돌회피 알고리즘을 실제 로봇과 똑같은 환경에 적용된 시뮬레이터를 통해 성능을 알아본다. 이동 로봇의 충돌회피를 위해 기존에 인공전위계 알고리즘과 Elastic force 알고리즘 등이 제안되어져있다. 본 연구에서는 시뮬레이션을 통해 이 두 가지 방법에 의한 동작시간과 경로의 이동 길이를 비교하였다. 시뮬레이터는 IPC(Inter Process Communication)를 기반으로 개발되어졌으며, 알고리즘의 비교에는 차륜형 이동 로봇을 사용하였다.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제5권2호
• /
• pp.188-198
• /
• 2013

In constructing a collision avoidance system, it is important to determine the time for starting collision avoidance maneuver. Many researchers have attempted to formulate various indices by applying a range of techniques. Among these indices, collision risk obtained by combining Distance to the Closest Point of Approach (DCPA) and Time to the Closest Point of Approach (TCPA) information with fuzzy theory is mostly used. However, the collision risk has a limit, in that membership functions of DCPA and TCPA are empirically determined. In addition, the collision risk is not able to consider several critical collision conditions where the target ship fails to take appropriate actions. It is therefore necessary to design a new concept based on logical approaches. In this paper, a collision ratio is proposed, which is the expected ratio of unavoidable paths to total paths under suitably characterized operation conditions. Total paths are determined by considering categories such as action space and methodology of avoidance. The International Regulations for Preventing Collisions at Sea (1972) and collision avoidance rules (2001) are considered to solve the slower ship's dilemma. Different methods which are based on a constant speed model and simulated speed model are used to calculate the relative positions between own ship and target ship. In the simulated speed model, fuzzy control is applied to determination of command rudder angle. At various encounter situations, the time histories of the collision ratio based on the simulated speed model are compared with those based on the constant speed model.

• 한국항해항만학회지
• /
• 제30권9호
• /
• pp.773-777
• /
• 2006

Significant increase of container flows in the marine terminals requires more efficient port equipments such as logistic and transfer systems. This paper presents collision avoidance and routing approach based on dynamic programming (DP) algorithm for a linear motor based shuttle car which is considered as a new transfer system in the port terminals. Most of routing problems are focused on automatic guided vehicle (AGV) systems, but its solutions are hardly utilized for LM based shuttle cars since both are mechanically different. Our proposed DP is implemented for real-time searching of an optimal path for each shuttle car in the Agile port terminal located at California in USA.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1916-1917
• /
• 2011

A development of a new moving obstacle avoidance algorithm using a delay-time Compensation for a network-based autonomous mobile robot is proposed in this paper. The moving obstacle avoidance algorithm is based on a Kalman filter through moving obstacle estimation and a Bezier curve for path generation. And, the network-based mobile robot, that is a unified system composed of distributed environmental sensors, mobile actuators, and controller, is compensated by a network delay compensation algorithm for degradation performance by network delay. The network delay compensation method by a sensor fusion using the Kalman filter is proposed for the localization of the robot to compensate both the delay of readings of an odometry and the delay of reading of environmental sensors. Through some simulation tests, the performance enhancement of the proposed algorithm in the viewpoint of efficient path generation and accurate goal point is shown here.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제54권5호
• /
• pp.291-299
• /
• 2005

An obstacle avoidance algorithm for a network-based autonomous mobile robot is proposed in this paper. The obstacle avoidance algorithm is based on the VFH(Vector Field Histogram) algorithm and two delay compensation methods with the VFH algorithm are proposed for a network-based robot with distributed environmental sensors, mobile actuators, and the VFH controller. Firstly, the environmental sensor information is compensated by prospection with acquired environmental sensor information, measured network delays, and the kinematic model of the robot. The compensated environmental sensor information is used for building polar histogram with the VFH algorithm. Secondly, a sensor fusion algorithm for localization of the robot is proposed to compensate the delay of odometry sensor information and the delay of environmental sensor information. Through some simulation tests, the performance enhancement of the proposed algorithm in the viewpoint of efficient path generation and accurate goal positioning is shown here.

• 한국컴퓨터그래픽스학회논문지
• /
• 제27권5호
• /
• pp.63-71
• /
• 2021

드론 자율비행 기술 중 장애물 회피는 드론이나 주변 환경의 손상을 방지하고 위험을 예방할 수 있도록 하는 매우 중요한 기술이다. LiDAR 센서 기반 장애물 회피방식은 비교적 높은 정확도를 보여 최근 연구에서 많이 활용되고 있지만, 단가가 높고 시각 정보에 대한 처리 능력이 제한적인 단점이 있다. 따라서 본 논문은 단가가 상대적으로 저렴하고 시각 정보를 이용한 확장성이 높은 카메라 기반 PPO(Proximal Policy Optimization) 강화학습을 이용한 드론의 장애물 회피 알고리즘을 제안한다. 3차원 공간상의 학습환경에서 드론, 장애물, 목표지점 등을 무작위로 위치시키고, 가상 카메라를 이용하여 전면에 설치된 스테레오 카메라를 통해 스테레오 영상정보를 얻은 다음 YOLOv4Tiny 객체검출을 수행한다. 그리고 난 후 스테레오 카메라의 삼각측량법을 통해 드론과 검출된 객체간의 거리를 측정한다. 이 거리를 기반으로 장애물 유무를 판단하고, 만약 장애물이면 패널티를 책정하고 목표지점이면 보상을 부여한다. 본 방법을 실험한 결과 카메라 기반 장애물 회피 알고리즘은 LiDAR 기반 장애물 회피 알고리즘과 비교하여 충분히 비슷한 수준의 높은 정확도와 평균 목표지점 도달시간을 보여 활용 가능성이 높음을 알 수 있었다.