• 초등상담연구
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• 제9권1호
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• pp.75-94
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• 2010

본 연구의 목적은 초등학교 4학년 학생들을 대상으로 수업행동의 개선을 위하여 수업행동을 수업 방해 행동과 수업 참여 행동으로 구분하고, 자기점검기법이 대상 아동들의 수업 방해 행동과 수업 참여행동에 어떠한 영향을 미치는지를 알아보고자 하는 데 있다. 이러한 연구목적을 달성하기 위해 설정한 연구문제는 첫째, 자기점검기법이 아동의 수업 방해 행동에 어떠한 영향을 미치는가. 둘째, 자기점검기법이 아동의 수업 참여 행동에 어떠한 영향을 미치는가를 밝히는 것이다. 연구 문제에 따른 연구 가설은 1. 자기점검기법은 아동의 수업방해행동을 감소시킬 것이다. 2. 자기점검 기법은 아동의 수업참여행동을 증가시킬 것이다로 세웠다. 연구 대상은 전라북도 J시에 소재하는 A초등학교 4학년 $\circledcirc$반 일반 학급 아동 12명으로 이는 기초선 기간의 행동측정 결과 수업 방해 행동 비율이 높은 8명과 수업 참여 행동 비율이 낮은 8명을 선정하였고, 양 쪽 그룹 모두에 속하는 아동이 4명이다. 이들의 사전 행동 관찰을 거쳐 개별적으로 수업 방해 행동 및 수업 참여 행동의 목표 행동을 설정하도록 하고, 기초선 1 기간 동안 각 행동의 빈도를 연구자가 두 명의 관찰자와 함께 측정하였다. 이후 중재 1 기간 동안 자기점검기법이 적용되었고, 아동 행동변화의 효과가 자기점검기법임을 밝히기 위하여 기초선 2 기간을 가졌다. 이후 중재 2 기간 동안 다시 자기점검기법이 실시되었으며, 10일 후 유지정도를 측정하기 위하여 사후 점검을 실시하였다. 개별 아동의 행동 발생 빈도를 변화 그래프를 이용하여 나타냈으며, 양적 결과의 제한점을 보완하기 위해 대상 아동들의 사후 소감문을 분석하였고, 연구자의 관찰내용을 제시하였다. 이 연구를 통해 얻어진 결과를 요약하면 첫째, 자기점검기법은 아동의 수업 방해 행동의 감소와 변화된 행동의 유지에 긍정적 효과를 미치는 것으로 나타났다. 둘째, 자기점검기법은 아동의 수업 참여 행동의 증가와 변화된 행동의 유지에 긍정적 효과를 미치는 것으로 나타났다.

• 대한전기학회논문지
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• 제39권4호
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• pp.403-413
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• 1990

A collision free trajectory control for multiple mobile robots in obstacle-resident workspace is proposed. The proposed method is based on the concept of neural optimization network which has been applied to such problems which are too complex to be handled by traditional analytical methods, and gives good adaptibility for unpredictable environment. In this paper, the positions of the mobile robot are taken as the variables of the neural circuit and the differential equations are derived based on the performance index which is the weighted summation of the functions of the distances between the goal and current position of each robot, between each pair of robots and between the goal and current position of each robot, between each pair of robots and between obstacles and robots. Also is studied the problem of local minimum and of detour in large radius around obstacles, which is caused by inertia of mobile robots. To show the validity of the proposed method an example is illustrated by computer simulation, in which 6 mobile robots with mass and friction traverse in a workspace with 6 obstacles.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제10권3호
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• pp.210-217
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• 2010

This paper presents integrated path planning and collision avoidance for an omni-directional mobile robot. In this scheme, the autonomous mobile robot finds the shortest path by the descendent gradient of a navigation function to reach a goal. In doing so, the robot based on the proposed approach attempts to overcome some of the typical problems that may pose to the conventional robot navigation. In particular, this paper presents a set of analysis for an omni-directional mobile robot to avoid trapped situations for two representative scenarios: 1) Ushaped deep narrow obstacle and 2) narrow passage problem between two obstacles. The proposed navigation scheme eliminates the nonfeasible area for the two cases by the help of the descendent gradient of the navigation function and the characteristics of an omni-directional mobile robot. The simulation results show that the proposed navigation scheme can effectively construct a path-planning system in the capability of reaching a goal and avoiding obstacles despite possible trapped situations under uncertain world knowledge.

• 한국지능시스템학회논문지
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• 제16권3호
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• pp.275-284
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• 2006

본 논문에서는 자율이동로봇이 주위 환경을 알지 못하는 상황에서 목표점까지 안전하게 주행하게 하는 주행 알고리즘에 대해 연구한다. 주행 알고리즘에서 가장 고려해야할 부분이 장애물 회피 알고리즘인데, 본 논문에서는 장애물 회피 알고리즘인 VFH(Vector Field Histogram) 알고리즘과 퍼지 알고리즘을 조합하여 여러 가지 형태의 환경에서 최적의 성능을 내도록 한다. 로봇이 처한 환경에 따라 상위 레벨의 supervisor가 위의 두 가지 장애물 회피 알고리즘 중 적절한 것을 선택하도록 조합하고, 다양한 환경에서 모의실험을 수행함으로써 제안된 로봇주행 알고리즘의 성능을 검증한다.

• 제어로봇시스템학회논문지
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• 제20권8호
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• pp.868-874
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• 2014

This paper proposes a novel mapping algorithm in Omni-directional Vision SLAM based on an obstacle's feature extraction using Lucas-Kanade Optical Flow motion detection and images obtained through fish-eye lenses mounted on robots. Omni-directional image sensors have distortion problems because they use a fish-eye lens or mirror, but it is possible in real time image processing for mobile robots because it measured all information around the robot at one time. In previous Omni-Directional Vision SLAM research, feature points in corrected fisheye images were used but the proposed algorithm corrected only the feature point of the obstacle. We obtained faster processing than previous systems through this process. The core of the proposed algorithm may be summarized as follows: First, we capture instantaneous $360^{\circ}$ panoramic images around a robot through fish-eye lenses which are mounted in the bottom direction. Second, we remove the feature points of the floor surface using a histogram filter, and label the candidates of the obstacle extracted. Third, we estimate the location of obstacles based on motion vectors using LKOF. Finally, it estimates the robot position using an Extended Kalman Filter based on the obstacle position obtained by LKOF and creates a map. We will confirm the reliability of the mapping algorithm using motion estimation based on fisheye images through the comparison between maps obtained using the proposed algorithm and real maps.

• Journal of Biosystems Engineering
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• 제3권1호
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• pp.1-19
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• 1978

Power tiller is a major unit of agricultural machinery being used on farms in Korea. About 180.000 units are introduced by 1977 and the demand for power tiller is continuously increasing as the farm mechanization progress. Major farming operations done by power tiller are the tillage, pumping, spraying, threshing, and hauling by exchanging the corresponding implements. In addition to their use on a relatively mild slope ground at present, it is also expected that many of power tillers could be operated on much inclined land to be developed by upland enlargement programmed. Therefore, research should be undertaken to solve many problems related to an effective untilization of power tillers on slope ground. The major objective of this study was to find out the travelling and tractive characteristics of power tillers being operated on general slope ground.In order to find out the critical travelling velocity and stability limit of slope ground for the side sliding and the dynamic side overturn of the tiller and tiller-trailer system, the mathematical model was developed based on a simplified physical model. The results analyzed through the model may be summarized as follows; (1) In case of no collision with an obstacle on ground, the equation of the dynamic side overturn developed was: $$\sum_n^{i=1}W_ia_s(cos\alpha cos\phi-{\frac {C_1V^2sin\phi}{gRcos\beta})-I_{AB}\frac {v^2}{Rr}}=0$$ In case of collision with an obstacle on ground, the equation was: $$\sum_n^{i=1}W_ia_s\{cos\alpha(1-sin\phi_1)-{\frac {C_1V^2sin\phi}{gRcos\beta}\}-\frac {1}{2}I_{TP} \( {\frac {2kV_2} {d_1+d_2}\)-I_{AB}{\frac{V^2}{Rr}} \( \frac {\pi}{2}-\frac {\pi}{180}\phi_2 \} = 0 $$ (2) As the angle of steering direction was increased, the critical travelling veloc\ulcornerities of side sliding and dynamic side overturn were decreased. (3) The critical travelling velocity was influenced by both the side slope angle .and the direct angle. In case of no collision with an obstacle, the critical velocity $V_c$ was 2.76-4.83m/sec at $\alpha=0^\circ$, $\beta=20^\circ$ ; and in case of collision with an obstacle, the critical velocity $V_{cc}$ was 1.39-1.5m/sec at $\alpha=0^\circ$, $\beta=20^\circ$ (4) In case of no collision with an obstacle, the dynamic side overturn was stimu\ulcornerlated by the carrying load but in case of collision with an obstacle, the danger of the dynamic side overturn was decreased by the carrying load. (5) When the system travels downward with the first set of high speed the limit {)f slope angle of side sliding was $\beta=5^\circ-10^\circ$ and when travels upward with the first set of high speed, the limit of angle of side sliding was $\beta=10^\circ-17.4^\circ$ (6) In case of running downward with the first set of high speed and collision with an obstacle, the limit of slope angle of the dynamic side overturn was = $12^\circ-17^\circ$ and in case of running upward with the first set of high speed and collision <>f upper wheels with an obstacle, the limit of slope angle of dynamic side overturn collision of upper wheels against an obstacle was $\beta=22^\circ-33^\circ$ at $\alpha=0^\circ -17.4^\circ$, respectively. (7) In case of running up and downward with the first set of high speed and no collision with an obstacle, the limit of slope angle of dynamic side overturn was $\beta=30^\circ-35^\circ$ (8) When the power tiller without implement attached travels up and down on the general slope ground with first set of high speed, the limit of slope angle of dynamic side overturn was $\beta=32^\circ-39^\circ$ in case of no collision with an obstacle, and $\beta=11^\circ-22^\circ$ in case of collision with an obstacle, respectively.

• 한국지능시스템학회논문지
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• 제22권2호
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• pp.218-224
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• 2012

최근에는, 초소형 AUV(Autonomous Underwater Vehicle)의 개발에 대한 요구가 증가하고 있으므로 그 요소 기술의 확보가 시급하다. 요소 기술의 하나로서 국부경로제어의 기존 연구에서는 주로 전방감시소나(Forward Looking Sonar : FLS)의 정보를 활용하고 있는데, FLS의 크기는 초소형 AUV에 적합하지 않으므로 장애물회피소나(Obstacle Avoidance Sonar : OAS)를 이용하는 것이 바람직하다. 요약하면, 초소형 AUV를 위한 OAS 기반의 국부경로제어 시스템은 다음과 같은 문제점들을 가지고 있다. 즉, OAS는 낮은 방위(bearing) 분해능 및 지역적인 거리(range) 정보를 제공하며, 임무시간을 증대하기 위해서 에너지 소비가 적은 시스템을 필요로 한다. 나아가, 구조 및 파라메터 관점에서 용이한 설계 절차를 요구한다. 이 문제를 해결하기 위해서 OAS 빔 모델링을 기반으로 진화 전략(Evolution Strategy : ES) 및 퍼지논리 제어기(Fuzzy Logic Controller : FLC)를 이용하는 지능형 국부경로제어 기법이 제안되었다. 제안된 기법의 성능을 검증하고 특성을 분석하기 위해서 수중비행체(Underwater Flight Vehicle : UFV)의 수평면 침로(course) 제어가 수행되었다. 시뮬레이션 결과는 제안된 기법에 있어서 실제 적용의 가능성과 추가 연구의 필요성을 보여준다.

• 대한수학교육학회지:수학교육학연구
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• 제11권1호
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• pp.89-102
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• 2001

Computer has been regarded as an alternative that could overcome the difficulties in the teaching and learning of mathematics. But the didactical problems of the computer-based environment for mathematics education could give us new obstacles. In this paper, first of all, we examined the application of the learning theories of mathematics to the computer environment. If the feedbacks of the computer are too immediate, students would have less opportunity to reflect on their thinking and focus their attention on the visual aspects, which leads to the simple abstraction rather than the reflective abstraction. We also examined some other Problems related to cognitive obstacle to learn the concepts of geometric figure and the geometric knowledge. Based on the analysis on the problems related to the computer-based environment of mathematics teaching and learning, we tried to find out the direction to use computer more adequately in teaching and learning geometry.

• 한국IT서비스학회지
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• 제7권4호
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• pp.87-99
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• 2008

As the technologies for telecommunication have been evolving, more enhanced information services and integrated information systems have been introduced, which can manage a variety of information from the heterogeneous systems. The major obstacle for the integrated information systems is the integrating heterogeneous databases in the systems and the heterogeneity problems can be classified into the structural and data heterogeneities. However, the previous researches have mainly highlighted into the solving structural heterogeneity problems. This paper identifies the data heterogeneity problems for multi-database schema integrations and proposes a new solving method. We analyze the semantics equivalence in data values based on the functional dependency, primary and candidate keys, and present a procedural solution of data heterogeneity in the perspective of the concept of attribute equivalence, integration key and conceptual integration table.

• 한국디지털건축인테리어학회논문집
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• 제3권2호
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• pp.20-29
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• 2003

It is an obstacle to improve living environments that an acute angle architectural design is often seen. Though that design give a stress to the neighborhood, we can't prevent the design taking place. We must control architectural design, because it is important to public worth and urban aesthetic. To prevent selfish architectural design, it is recommend to extend design review and reflect neighborhood opinions.