• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1133-1137
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• 1995

This paper presents a numerical method of the global search for an optimal geometric path for a manipulator arm amid obstacles. Finite term quintic B-splines are used to describe an arbitrary point-to-point manipulator motion with fixed moving time. The coefficients of the splines span a linear vector space, a point in which uniquely represents the manipulator motion. All feasible geometric paths are searched by adjusting the seed points of the obstacle models in the penetration growth distances. In the numerical implementation using nonlinear programming, the globally optimal geometric path is obtained for a spatial 3-link(3-revolute joints) manipulator amid several hexahedral obstacles without simplifying any dynamic or geometric models.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.4
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• pp.493-498
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• 2004

A novel approach for path planning of a polygonal robot is presented. Traditional path planners perform extensive geometric searching to find the optimal path or to prove that there is no solution. The computation required to prove that there is no solution is equivalent to exhaustive search of the motion space, which is typically very expensive. Humans seems to use a set of several different path planning strategies to analyse the situation of the obstacles in the environment, and quickly recognize whether the path-planning problem is easy to solve, hard to solve or has no solution. This human path-planning strategies have motivated the development of the presented algorithm that combines qualitative shape reasoning and exhaustive geometric searching to speed up the path planning process. It has three planning stages consisting of identification of no-solution cases based on an enclosure test, a qualitative reasoning stage, and finally a complete search algorithm in case the previous two stages cannot determine of the existence of a solution path.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.204-213
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• 1999

This paper suggests a numerical method of finding optimal geometric path and minimum-time motion for a manipulator arm. To find the minimum-time motion, the optimal geometric path is searched first, and the minimum-time motion is searched on this optimal path. In the algorithm finding optimal geometric path, the objective function is minimizing the combination of joint velocities, joint-jerks, and actuator forces as well as avoiding several static obstacles, where global search is performed by adjusting the seed points of the obstacle models. In the minimum-time algorithm, the traveling time is expressed by the linear combinations of finite-term quintic B-splines and the coefficients of the splines are obtained by nonlinear programming to minimize the total traveling time subject to the constraints of the velocity-dependent actuator forces. These two search algorithms are basically similar and their convergences are quite stable.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.432-432
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• 2021

우리나라는 대부분의 에너지 공급을 해외에 의존하고 있는 실정이다. 산업통상자원부와 에너지경제연구원에서 발간하는 2018년 에너지통계연보(에너지경제연구원과 산업통상자원부, 2018)에 실린 2010년부터 2017년까지의 에너지수급 균형을 보면 원유, 천연가스, 석탄, 우라늄 등 평균 95.4%의 에너지를 수입하고 있는 실정이다. 수력 및 신재생에너지의 경우 기후변화에 대응하는 수단 그리고 정부의 저탄소에너지 전환 정책으로 인정받아 상대적으로 낮은 에너지 경제성에도 불구하고 꾸준히 보급되고 있다. 우리나라뿐만 아니라 독일, 프랑스, 영국, 중국 그리고 인도와 같은 세계 주요 국가들이 친환경 에너지 정책을 주도함에 따라 향후 신재생에너지의 공급 규모는 크게 확대될 것으로 전망된다. 중력 물 보텍스 마이크로 수력 발전 시스템은 시스템의 상하류부의 수두(hydraulic head) 차에 의해 저류조(basin)에서 발생되는 물의 보텍스 즉 소용돌이(whirlpool)를 이용하여 임펠러(impeller)를 회전시켜 전기에너지를 생산하는 친환경적 재생에너지의 일종이다. 또한, 시스템으로 유입되는 물은 전기에너지 생산을 위한 임펠러를 통과한 후 다시 하천으로 방류되므로 하천 수의 손실 그리고 하천의 물길도 거의 교란 시키지 않는다. 4가구 정도의 연간 가정용 전기 요구량인 12와 15kW 사이의 전기에너지를 생산하기 위해서는 발전시스템의 상류와 하류의 수두차가 단지 1.5에서 1.7m 이하이면 충분한 것으로 알려져 있다. 본 연구에서는 중력 물 보텍스 친환경 마이크로 발전 시스템을 구성하는 저류조(basin)에 대해 최대 발전효율을 발생시키기에 최적인 기하학적 형태를 도출하는 것이며, 이를 위해 저류조의 cone angle에 따른 다양한 저류조 직경 및 물 보텍스 생성을 위한 저류조 형태의 변화, 유입수로와 저류조와의 각도인 notch angle의 변화, 유입부 폭과 유출부 직경, 유입수로의 길이 그리고 유입수로에서의 초기수심과 같은 기하학적 매개변수를 변화시켜 모의를 수행하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.5
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• pp.609-617
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• 2013

This paper presents a near-minimum time path planning algorithm for autonomous driving. The problem of near-minimum time path planning is an optimization problem in which it is necessary to take into account not only the geometry of the circuit but also the dynamics of the vehicle. The path planning algorithm consists of a candidate path generation and a velocity optimization algorithm. The candidate path generation algorithm calculates the compromises between the shortest path and the path that allows the highest speeds to be achieved. The velocity optimization algorithm calculates the lap time of each candidate considering the vehicle driving performance and tire friction limit. By using the calculated path and velocity of each candidate, we calculate the lap times and search for a near-minimum time path. The proposed algorithm was evaluated via computer simulation using CarSim and Matlab/Simulink.

• Journal of Korean Society of Steel Construction
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• v.12 no.3 s.46
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• pp.317-328
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• 2000

The objective of the research is to develop an algorithm for the optimum design of two-dimensional braced steel frames using an advanced analysis, which considers both material and geometric nonlinearties. Since both nonlinearties are considered in analysis process, Optimum design algorithm which does not require to calculate K-factor is presented. A multi-level discrete optimization technique with two parameters that uses the information of structural system and separate member has been developed. The structural analysis is performed by the relined plastic-hinge method which is based on zero-length plastic hinge theory. Optimization problem are formulated by AISC-LRFD code. The feasibility, validity and efficiency of the developed algorithm is demonstrated by the results of the braced steel frame.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2774-2776
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• 2005

본 논문에서는 이동로봇에 삼차원 레이저 스캐너를 장착하여 삼차원 데이터의 수집, 수집된 데이터의 정합, 데이터 수집을 위한 이동로봇의 경로계획 및 장애물 회피주행 등 모든 작업들을 유기적으로 결합시켜 실내 환경에 다한 삼차원 모델을 자율제작하는 시스템을 제안한다. 이를 위해 스캔순서최적화를 통한 빠른 동적 물체 정보의 제거, 계층적 육면체 맵과 기하학적맵을 이용한 최적 경로 예측에 의한 다음 스캐닝 위치의 결정, 오도미터 정보와 명암 정보를 이용해 수정된 ICP 알고리즘을 통한 데이터의 정합을 통하여 이동물체와 관계없는 실내환경에 대한 삼차원 모델의 자율복원 한다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.5 s.305
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• pp.1-12
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• 2005

A Mobile manipulator - a serial connection of a mobile robot and a task robot - is a very useful system to achieve various tasks in dangerous environment. because it has the higher performance than a fixed base manipulator in regard to the size of it's operational workspace. Unfortunately the use of a mobile robot introduces non-holonomic constraints, and the combination of a mobile robot and a manipulator generally introduces kinematic redundancy. In this paper, first a method for estimating the position of object at the cartesian coordinate system acquired by using the geometrical relationship between the image captured by 2-DOF active camera mounted on mobile robot and real object is proposed. Second, we propose a method to determine a optimal path between current the position of mobile manipulator whose mobile robot is non-holonomic and the position of object estimated by image information through the global displacement of the system in a symbolic way, using homogenous matrices. Then, we compute the corresponding joint parameters to make the desired displacement coincide with the computed symbolic displacement and object is captured through the control of a manipulator. The effectiveness of proposed method is demonstrated by the simulation and real experiment using the mobile manipulator.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.116-126
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• 2001

This paper suggests a numerical method to find optimal geometric path and minimum-time motion for a spatial 6-link manipulator arm (PUMA 560 type). To find a minimum-time motion, the optimal geometric paths minimizing 2 different dynamic performance indices are searched first, and the minimum-time motions are searched on these optimal paths. In the algorithm to find optimal geometric paths, the objective functions (performance indices) are selected to minimize joint velocities, actuator forces or the combinations of them as well as to avoid one static obstacle. In the minimum-time algorithm the traveling time is expressed by the power series including 21 terms. The coefficients of the series are obtained using nonlinear programming to minimize the total traveling time subject to the constraints of velocity-dependent actuator forces.

• Journal of the Korea Computer Graphics Society
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• v.28 no.3
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• pp.55-65
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• 2022

Recently, deep learning-based automated systems for identifying and detecting landmarks have been proposed. In order to train such a deep learning-based model without overfitting, a large amount of image and labeling data is required. Conventionally, an experienced reader manually identifies and labels landmarks in a patient's image. However, such measurement is not only expensive, but also has poor reproducibility, so the need for an automated labeling method has been raised. In addition, in the X-ray image, since various human tissues on the path through which the photons pass are displayed, it is difficult to identify the landmark compared to a general natural image or a 3D image modality image. In this study, we propose a geometric data augmentation technique that enables the generation of a large amount of labeling data in X-ray images. In addition, the optimal attention mechanism for landmark detection was presented through the implementation and application of various attention techniques to improve the detection performance of 16 major landmarks in the skull. Finally, among the major cranial landmarks, markers that ensure stable detection are derived, and these markers are expected to have high clinical application potential.