• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.1
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• pp.19-24
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• 2011

This paper presents a method about amorphous obstacles avoidance for local path planning in the two-dimensional sensor environment. In particular, the proposed method is extended from some of the recent studies about a point obstacle avoidance. In the paper, repulsive forces of two types are proposed in order that the robot avoids from the amorphous obstacle with various size and form. A judgment of curvatures in the proposed method simplifies the recognition of obstacles to make the path-planning efficient. In addition, the line of sight(LOS) and the range of recognition are considered in the environment. By simulation results, the proposed method for amorphous obstacle avoidance shows better performance than the related existing method and we confirmed advantages of proposed method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.2
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• pp.127-133
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• 2014

This paper proposes a determination method of waypoints to maximize the survivability of a UAV. Voronoi diagram which is used for the initial selection of waypoint candidates is the most widely used path planning technique to avoid the threat as far as possible when the location and strength of the threat are given. But if threat strength is different each other and flight path is constrained along with straight lines, Voronoi diagram has limitations in real applications. In this study, the initial waypoints obtained from Voronoi diagram are optimized considering the shape of each threat. Here, a waypoint is optimized while adjacent waypoints are fixed. By repeating this localized optimization until whole waypoints are converged, computation time for finding the best waypoints is greatly reduced.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2008.04a
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• pp.97-100
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• 2008

본 논문에서는 자율주행 로봇의 제어를 위한 온톨로지 설계 방법을 제안한다. 제안한 방법은 '감지', '획득', '인식', '(경로 ${\cdot}$ 행동)계획', '행동'의 다섯 단계로 구성된 '인지 사이클'에서 '감지', '행동계획', '행동' 단계를 온톨로지를 이용하여 구현함으로써 온토롤지에 의한 로봇의 제어가 가능하도록 한다. 즉, '감지' 단계에서는 자율주행 로봇이 센서를 통해 감지한 환경 정보를 온톨로지로 표현하고, '행동계획' 단계에서는 온톨로지를 이용하여 로봇 주변의 상황에 따른 국소 영역에서의 로봇의 행동을 계획하며, '행동' 단계에서는 온톨로지를 통해 로봇 구동부의 제어가 가능하도록 한다. 그리고 차동구동형 로봇을 제작하고, 실제 환경에서의 실험을 통해 그 타당성을 검증한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1881_1882
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• 2009

Simple quadratic potential functions for unicycle robot path planning are presented, where proposed algorithm for path planning has the different environment for each robot based on LOS(Line Of Sight) between a target and an obstacle, unlike a conventional path planning. In doing so, the proposed algorithm assumes that each swarm robot equips its own vision instead of a ceiling camera. In particular, this paper presents that each robot follows its different local leader. As a result proposed algorithm reduces local minimum problems by the help of each local leader.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.726-730
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• 1990

In this paper, assuming that local range information is available, a collision-free path planning algorithm for multiple mobile robots is presented by using Hopfield neural optimization network. The energy function of the network is built using the present position and the goal position of each robot as well as its local range information. The proposed algorithm has several advantages such as the effective passing around obstacles with the directional safety distance, the easy implementation of robot motion planning including its rotation, the real-time path planning capability from the totally localized computations of path for each robot, and the adaptivity on arbitrary environment since any special shape of obstacles is not assumed.

• Journal of Educational Research in Mathematics
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• v.18 no.1
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• pp.25-50
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• 2008

Several previous studies suggested that simulation could be a main didactic instrument in overcoming misconception and probability modeling. However, they have not described enough how to reorganize probability knowledge as knowledge to be taught in a curriculum using simulation. The purpose of this study is to identify the theoretical knowledge needed in developing a didactic transposition method of probability knowledge using simulation. The theoretical knowledge needed to develop this method was specified as follows : pseudo-contextualization/pseudo-personalization, and pseudo-decontextualization/pseudo-deper-sonalization according to the introductory purposes of simulation. As a result, this study developed a local instruction theory and an hypothetical learning trajectory for overcoming misconceptions and modeling situations respectively. This study summed up educational intention, which was designed to transform probability knowledge into didactic according to the introductory purposes of simulation, into curriculum, lesson plans, and experimental teaching materials to present didactic ideas for new probability education programs in the high school probability curriculum.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.4
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• pp.306-313
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• 2014

Impacted teeth are teeth with a delayed eruption time or that are expected to erupt incompletely. Those teeth can cause a series of potential problems such as root displacement and resorption, periodontal problems in adjacent teeth, referred pain and the formation of cysts and odontogenic tumors. The purpose of this study was to investigate characteristics and treatment of child and adolescent patients younger than 15 years of age that were diagnosed with an impacted tooth who visited the Chosun University Dental Hospital. The impacted tooth, its etiology, treatment and traction period were surveyed through electric medical records, radiographs in 335 patients. We excluded the impacted third molar, supernumerary and deciduous teeth from this study. The most frequently impacted teeth are upper canine, followed by the upper incisor. The most common etiologies of impaction were an abnormal eruption pathway and localized pathologic lesions. The treatment of an impacted tooth was mostly orthodontic traction. The traction period was relatively short in cases with distinct obstacles, with an impacted upper incisor and if patients were younger. An orthodontic traction is considered to be more unfavorable if the patient gets older. Therefore, an early diagnosis and a precise treatment plan through a regular check-ups are mandatory.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.625-630
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• 2009

Root resorption of primary teeth usually occurs as the succeeding permanent teeth erupt, which induces differentiation of the hemopoietic cells into osteoclasts. Their root resorption pattern reflects the eruption path of the succeeding permanent teeth, and eventually the primary teeth shed as their succeeding permanent teeth erupt. Even when a permanent tooth germ is congenitally missing, root resorption of the corresponding primary tooth may still occur due to various factors, such as inflammation, traumatic occlusal force, and weakness of periodontium etc. Such congenital missing of permanent teeth is a commonly observed phenomenon in human be ing, and it often accompanies delayed retention of primary teeth. The etiologic factors for congenital missing in elude not only systemic diseases, but also local factors and human evolution process. In the radiographs of the cases in this report, the primary teeth without succeeding permanent teeth show pathologic root resorption. Root resorption progressed about 1/2~3/4 of the roots, and the surfaces of the resorption area were irregular. Considering high susceptibility of the periodontal ligament of primary teeth to root resorption, pathologic root resorption of primary teeth with delayed retention can be explained by the increased masticatory muscle force and abnormal occlusion developed during the mixed dentition. When the primary teeth without succeeding permanent teeth are lost, decision for space maintenance is required and long-term treatment plan for further prosthetic or orthodontic treatment should be establsihed.