• Journal of Korean Society of Transportation
• /
• v.16 no.4
• /
• pp.195-212
• /
• 1998

본 연구는 새로운 설계일관성 검토기법의 정립을 위하여 수행되었으며, 이를 위해 속도추정 모형을 개발하였다. 본 연구를 통해 개발된 모형은 차량의 주행속도에 가장 큰 영향을 미치는 주 요소를 고려한 장점을 지니고 있다. 즉 평면곡선에서는 운전자의 시각적 판단을 기초로 등판차량의 주행속도를 추정하였다. 또한 이러한 속도추정이 승용차뿐만 아니라 트럭의 경우로 나누어 이루어짐으로써, 차종별 고려가 가능하도록 하였다. 다음은 본 연구를 통해 이루어진 결과이다. 평면곡선에서는 승용차와 트럭의 속도가 같게 추정되었으며, 시거를 통해 산정된 추정속도는 곡선반경과 밀접한 관계를 갖는다. 종단선형에서 승용차의 속도는 구배의 영향을 받지 않으나, 트럭은 구배의 영향으로 속도가 감소한다. 이 때 트럭에 작용되는 가속도는 모두 세 종류로써, 첫째, crawl speed에 도달할 때까지 작용한 가속도$(a_1)$와 둘째, crawl speed 이후 작용한 가속도$(a_2)$ 그리고 셋째, 하향구배 주행시 작용된 가속도$(a_3)$로 구분된다. Watanatade가 제시한 것과 같이 평지에서 나타나는 평면곡선의 주행속도와 구배지에서의 속도를 단순 비교 함으로써, 작은 속도의 궤적을 따라 평지에서 나타나는 평면곡선의 주행속도와 구배지에서의 속도를 단순 비교함으로써, 작은 속도의 궤적을 따라 합성선형의 속도를 추정하는 것은 합성선형이 차량의 주행속도에 미치는 영향을 간과한 것으로 판단할 수 있다. 그러나 본 모형에서는 합성선형의 영향을 고려하여 승용차와 트럭의 주행속도를 추정함으로써, 보다 현실적으로 주행속도를 추정하였다. 본 연구의 결과는 도로의 설계일관성을 검토하는데 매우 유용한 도구가 될 것이며 향후 운전자의 희망속도 결정, 감속율의 산정, 교통류의 고려, 도로설계의 전산화 자료와 연결 등을 통해 보다 실용적인 결과를 산출할 수 있을 것이다.

• Journal of KIISE:Computer Systems and Theory
• /
• v.37 no.1
• /
• pp.27-34
• /
• 2010

Web crawlers are fundamental programs which iteratively download web pages by following links of web pages starting from a small set of initial URLs. Previously several web crawling orderings have been proposed to crawl popular web pages in preference to other pages, but some graph search techniques whose characteristics and efficient implementations had been studied in graph theory community have not been applied yet for web crawling orderings. In this paper we consider various graph search techniques including lexicographic breadth-first search, lexicographic depth-first search and maximum cardinality search as well as well-known breadth-first search and depth-first search, and then choose effective web crawling orderings which have linear time complexity and crawl popular pages early. Especially, for maximum cardinality search and lexicographic breadth-first search whose implementations are non-trivial, we propose linear-time web crawling orderings by applying the partition refinement method. Experimental results show that maximum cardinality search has desirable properties in both time complexity and the quality of crawled pages.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.4
• /
• pp.356-361
• /
• 2020

This paper presents a lightweight milli-scale crawling robot that can crawl on both sides, which was inspired by the movement of insects. This robot has an excellent ability to overcome obstacles, such as the narrow gaps and the rough terrain. In addition, the robot can crawl steadily and rapidly through triangular alternation, such as ants or cockroaches. The process of smart composite microstructures (SCM) was employed to make a lightweight robot structure. The SCM process replaced the conventional mechanical parts with flexure joints and composite links, which allows the weight of the robot to be reduced. In addition, the robot structure was robust against external impacts owing to the compliance of the constituent materials. Using the SCM process, the robot weighed only 32g with twelve legs in total on both sides. The robot showed a crawling speed of 0.52m/s on the front side and 0.42m/s on the backside.

• Journal of Information Technology Services
• /
• v.19 no.4
• /
• pp.1-11
• /
• 2020

Through text mining, sentiment analysis, and semiotics analysis, this study aims to reinterpret the meaning of user emotional words and related words to derive strategic elements of brand and design. After selecting a local car manufacturer whose user opinion on the brand is a clear topic, web-crawl the car comments of the manufacturer directly created by the users online. Then, analyze the extracted morphology and its associated words and convert them to fit the marketing mix theory. Through this process, propose a methodology that allows consumers to supplement and improve brand elements with negative sensibilities, and to inherit elements with positive sensibilities and manage brands reasonably. In particular, the Map presented in this study are considered to be fully utilized as information for overall brand management.

• Korean Journal of Applied Biomechanics
• /
• v.12 no.2
• /
• pp.393-405
• /
• 2002

When our body is immersed in water, we experience weightlessness. The degree of weightlessness that we experience varies depending on the proportion of the body immersed in water, being governed by the relationship between the weight of body and the buoyant force acting on the body. Human body during the performance of swimming in no exception to these influences. Swimmers body is subject to a time and position dependent force system. Even the magnitude of the buoyant force acting on the swimmers body at every given instant and the corresponding position of the CB change continuously. The findings of this study support the following conclusions. The buoyancy torque was the primary source of bodyroll exhibited by front crawl swimmers performing at distance pace, accounting for 88 % of the bodyroll. Faster swimmers used buoyancy more effectively to generate bodyroll, partially supporting the postulation that an effective use of buoyancy for bodyroll may reduce the generated hydrodynamic forces to be wasted in non-propulsive directions and maximize forward propulsion.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.924-927
• /
• 1996

In this work, we investigate the quasi-static crawling of the four-bar mechanism. Since the crawling of the mechanism is based on sliding of contact points of the mechanism with the ground, interaction forces and friction forces at contact points of the mechanism with the ground should be computed. For this purpuse, we introduce the concept of imaginary joints to find these forces. Therefore, we are able to treat the closed mechanism as a serial one. Also, sliding conditions of the mechanism in quasi-static equilibrium are examined. Lastly, the required torques for the mechanism to crawl with respect to various configurations of the mechanism but with a fixed ground friction are investigated.

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.68.1-68
• /
• 2002

This paper considers a rough neurocomputing approach to the design of the classify layer of a Brooks architecture for a robot control system. The Paradigm for neurocomputing that has its roots in rough set theory, and works well in cases where there is uncertainty about the values of measurements used to make decisions. In the case of the line-crawling robot (LCR) described in this paper, rough neurocomputing is used to classify sometimes noisy signals from sensors. The LCR is a robot designed to crawl along high-voltage transmission lines where noisy sensor signals are common because of the electromagnetic field surrounding conductors. In rough neurocomputing, training a network of neurons...

• Journal of Institute of Control, Robotics and Systems
• /
• v.11 no.7
• /
• pp.595-601
• /
• 2005

A mobile robot system utilizing NDT (Non-Destructive Testing) method is designed and fabricated f3r automatic integrity evaluation of large sized industrial reservoirs and pipelines. The developed mobile robot can crawl over the outer surface of the industrial facilities even though the shape of the structures is various and unsymmetric. The robot detects defects such as pinholes, cracks and thickness reduction at the wall of the facilities using EMAT (Electro-Magnetic Acoustic Transducer). Image processing technology for weld line detection at the surface of the target and host programs including defect detecting algorithms are also developed. Automation of defect detection for these kinds of large facilities using mobile robots is helpful to prevent significant troubles of the structures without danger of human beings under harmful environment.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.3
• /
• pp.226-232
• /
• 2002

In this work, the quasi-static crawling of the four-bar mechanism is investigated. Since the crawling of the mechanism is based on sliding of contact points of the mechanism with the ground, interaction forces and friction forces at contact points of the mechanism with the ground should be computed. For this purpose, we introduce the concept of imaginary joints to find these forces and treat the closed mechanism as a serial one. Lastly, the required torques for the mechanism to crawl with respect to various configurations of the mechanism on a flat ground with uniform friction coefficient, based on sliding conditions of the mechanism in quasi-static equilibrium, are investigated.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.10d
• /
• pp.135-139
• /
• 2006

Today's social networking services have tens of millions of users, and are growing fast. Their sheer size poses a significant challenge in capturing and analyzing their topological characteristics. Snowball sampling is a popular method to crawl and sample network topologies, but requires a high sampling ratio for accurate estimation of certain metrics. In this work, we evaluate how close topological characteristics of snowball sampled networks are to the complete network. Instead of using a synthetically generated topology, we use the complete topology of Cyworld ilchon network. The goal of this work is to determine sampling ratios for accurate estimation of key topological characteristics, such as the degree distribution, the degree correlation, the assortativity, and the clustering coefficient.