• 무역상무연구
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• 제30권
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• pp.27-58
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• 2006

The purpose of this study is to identify key obstacles to the adoption of electronic bill of lading and to suggest an effective way to promote the utilization of electronic bill of lading in international trade field. This study finds that all the respondants have not used 'true' electronic bill of lading that is issued and distributed electronically, and most of them agreed the needs of e-B/L adoption, but their intentions to adopt e-B/L remain very low in the present situation. Five obstacles to the adoption of e-B/L were derived from an explanatory factor analysis: 'integration' factor, 'law institution' factor, 'usability' factor, 'economic efficiency' factor, and 'security' factor. Solutions to promote the utilization of e-B/L in international trade field are as follows; Firstly, to endow e-B/L with the legal force through amending relevant laws including the commercial law. Secondly, to conclude the relevant international agreement, and to carry out joint projects between nations are needed. Thirdly, to conduct publicity campaigns is required to increase the understanding of the concepts and benefits of e-B/L to all concerned parties. Fourthly, stable and reliable system must be constructed with high level security. Fifthly, to readjust the service fee of e-B/L system to a realistic level is to be needed in order for user companies to use e-B/L service.

• 한국정보통신학회논문지
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• 제18권5호
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• pp.1022-1027
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• 2014

본 논문에서는 DGPS 단축형 모노폴 안테나와 안테나 사이트 환경을 모델링하여 안테나 주변 환경에 따른 안테나 성능을 분석한다. DGPS 기준국 안테나의 성능 해석을 위한 모델링을 해석하고 대지 도전율이나 전파 장애물에 의한 안테나 성능을 모의 분석하여 DGPS 안테나 설치에 요구되는 사이트 환경을 정립한다. 일정한 접지 면에 적정한 방사형 접지를 갖는 안테나 사이트는 대지 도전율이나 전파 장애물로 인한 안테나 정합회로에 대한 영향은 적으나, 방사 효율 영향은 크게 나타난다. 안정된 DGPS 서비스를 위해서는 안테나 사이트의 양호한 대지 도전율이외에 주변에 전파 장애물이 없는 평탄한 안테나 사이트가 중요하다.

• 로봇학회논문지
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• 제18권4호
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• pp.487-495
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• 2023

This paper presents a method for autonomous exploration of indoor environments using a 2-dimensional Light Detection And Ranging (LiDAR) scanner. The proposed frontier-based exploration method considers navigability from the current robot position to extracted frontier targets. An approach to constructing the point cloud grid map that accurately reflects the occupancy probability of glass obstacles is proposed, enabling identification of safe frontier grids on the safety grid map calculated from the point cloud grid map. Navigability, indicating whether the robot can successfully navigate to each frontier target, is calculated by applying the skeletonization-informed rapidly exploring random tree algorithm to the safety grid map. While conventional exploration approaches have focused on frontier detection and target position/direction decision, the proposed method discusses a safe navigation approach for the overall exploration process until the completion of mapping. Real-world experiments have been conducted to verify that the proposed method leads the robot to avoid glass obstacles and safely navigate the entire environment, constructing the point cloud map and calculating the navigability with low computing time deviation.

• Industrial Engineering and Management Systems
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• 제3권1호
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• pp.78-84
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• 2004

To optimize movement of a multi-joint robot arm is known to be a difficult problem, because it is a kind of redundant system. Although the end-effector is set its position by each angle of the joints, the angle of each joint cannot be uniquely determined by the position of the end-effector. There exist the infinite number of different sets of joint angles which represent the same position of the end-effector. This paper describes how to manage the angle of each joint to move its end-effector preferably on an X-Y plane with obstacles in the end-effector’s reachable area, and how to optimize the movement of a multi-joint robot arm, evading obstacles. The definition of “preferable” movement depends upon a purpose of robot operation. First, we divide viewpoints of preference into two, 1) the standpoint of the end-effector, and 2) the standpoint of joints. Then, we define multiple objective functions, and formulate it into a multi-objective programming problem. Finally, we solve it using multi-purpose genetic algorithm, and obtain reasonable results. The method described here is possible to add appropriate objective function if necessary for the purpose.

• International Journal of Aeronautical and Space Sciences
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• 제10권2호
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• pp.1-11
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• 2009

In this paper, two algorithms to solve the path planning problem with constraints from obstacles are presented. One proposed Algorithm is "Grid point-based path planning". The first step of this algorithm is to set points which can be the waypoints around the field. These points can be located inside or outside of the field or the obstacles. Therefore, we should determine whether those points are located in the field or not. Using the equations of boundary lines for a region that we are interested in is an effective approach to handle. The other algorithm is based on the boundary lines of the agricultural field, and the concept of this algorithm is well known as "boustrophedon method". These proposed algorithms are simple but powerful for complex cases since it can generate a plausible path for the complex shape which cannot be represented by using geometrical approaches efficiently and for the case that some obstacles or forbidden regions are located on the field by using a skill of discriminants about set points. As will be presented, this proposed algorithm could exhibit a reasonable accuracy to perform an agricultural mission.

• 제어로봇시스템학회논문지
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• 제11권2호
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• pp.137-143
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• 2005

Autonomous mobile robot has an ability to navigate using both map in known environment and sensors for detecting obstacles in unknown environment. In general, autonomous mobile robot navigates by global path planning on the basis of already made map and local path planning on the basis of various kinds of sensors to avoid abrupt obstacles. This paper provides a global path planning method using self-organizing feature map which is a method among a number of neural network. The self-organizing feature map uses a randomized small valued initial weight vectors, selects the neuron whose weight vector best matches input as the winning neuron, and trains the weight vectors such that neurons within the activity bubble are move toward the input vector. On the other hand, the modified method in this research uses a predetermined initial weight vectors, gives the systematic input vector whose position best matches obstacles, and trains the weight vectors such that neurons within the activity bubble are move toward the input vector. According to simulation results one can conclude that the modified neural network is useful tool for the global path planning problem of a mobile robot.

• 한국전문물리치료학회지
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• 제18권3호
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• pp.16-25
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• 2011

This study aimed to evaluate factors related to the ability of ambulatory patients with cerebral palsy (CP) to walk over vertical and horizontal obstacles. Twenty patients with spastic CP who were able to walk independently for at least 10 m with or without walking devices were recruited for the study. Participants were required to walk over small obstacles (1, 4, and 8 cm in height or width; total of 6 conditions). A 'fail' was recorded when either the lower limbs or the walking device contacted the obstacle. Linear regression analyses were used to determine the effects of age, sex, walking devices, eyeglasses, subtype (hemiplegia or diplegia), ankle foot orthoses, functional level, and score of body mass index on the ability of obstacle crossing. Fifteen participants (75%) failed to adequately clear the foot or walking device over obstacles in at least 1 condition. The chance of failure in crossing vertical obstacle was affected by the use of ankle foot orthoses, eyeglasses, gender, and CP subtype (p<.05). The failure rate crossing horizontal obstacle was affected by CP subtype. These findings suggest that rehabilitation procedures should (1) consider the clinical characteristics of patients in order to prepare them to be more independent while performing daily activities, and (2) incorporate environmental conditions that patients encounter at home and in the community.

• 한국항공운항학회지
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• 제24권2호
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• pp.25-30
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• 2016

Obstacle defines all fixed and mobile objects, or parts thereof, that are located on an area intended for the surface movement of aircraft or extend above a defined surface intended to protect aircraft in flight or stand outside those defined surfaces and that have been assessed as being a hazard to air navigation. The airspace around airports are maintained free from obstacles so as to permit the intended aeroplane operations at the airports to be conducted safely and to prevent the airports from becoming unusable by the growth of obstacles around the airports. This is achieved by establishing a series of obstacle limitation surfaces or airspace imaginary surfaces that define the limits to which objects may project into the airspace. This is a case study that shows an application of obstacle limitation criteria, which must be maintained free from an critical obstacle, for specific conditions of two airports. For the purpose of the application, aeronautical studies/flight safety influence assessments were used to identify possible solutions and select a solution that is acceptable without degrading aviation safety.

• 동력기계공학회지
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• 제17권5호
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• pp.112-120
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• 2013

In this study, we propose an improved view-based navigation method for obstacle avoidance and evaluate the effectiveness of the method in real environments with real obstacles. The proposed method possesses the ability to estimate the position and rotation of a mobile robot, even if the mobile robot strays from a recording path for the purpose of avoiding obstacles. In order to achieve this, ego-motion estimation was incorporated into the existing view-based navigation system. The ego-motion is calculated from SURF points between a current view and a recorded view using a Kinect sensor. In conventional view-based navigation systems, it is difficult to generate alternate paths to avoid obstacles. The proposed method is anticipated to allow a mobile robot greater flexibility in path planning to avoid humans and objects expected in real environments. Based on experiments performed in an indoor environment using a mobile robot, we evaluated the measurement accuracy of the proposed method, and confirmed its feasibility for robot navigation in museums and shopping mall.

• 한국컴퓨터정보학회논문지
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• 제13권2호
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• pp.243-250
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• 2008

최근 슬램 알고리즘의 실현을 통해 주변 환경에 대한 맵 정보가 획득 가능할 경우에 격자 그리드 기반의 Boustrophedon 경로 기반 커버리지 알고리즘이 매우 효율적인 것으로 알려져 있다. 그러나 Boustrophedon 경로 기반 알고리즘은실내 공간에 장애물이 복잡하게 존재할 경우에는 급격히 성능 저하현상이 발생한다. 따라서 본 논문에서는 복잡한 실내 공간에서도 효율적으로 빠른 시간 내에 청소를 완료할 수 있는 Group-k 알고리즘을 제안하고 구현한다. Group-k 알고리즘은 전체 공간을 장애물의 복잡성에 근거하여 전체 공간을 그룹화하고 각 그룹별 우선순위를 부여하여 전체 작업 순서를 효율적으로 제어한다. 구현 기반의 실험에 의하면, 본 논문에서 제안된 알고리즘은 Boustrophedon 경로 기반 알고리즘에 비해 약 20%의 성능 향상을 보여준다.