• 로봇학회논문지
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• 제18권2호
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• pp.143-154
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• 2023

In this study, a fast motion planning method for the swing motion of a 6x6 wheel-legged robot to traverse large obstacles and gaps is proposed. The motion planning method presented in the previous paper, which was based on trajectory optimization, took up to tens of seconds and was limited to two-dimensional, structured vertical obstacles and trenches. A deep neural network based on one-dimensional Convolutional Neural Network (CNN) is introduced to generate keyframes, which are then used to represent smooth reference commands for the six leg angles along the robot's path. The network is initially trained using the behavioral cloning method with a dataset gathered from previous simulation results of the trajectory optimization. Its performance is then improved through reinforcement learning, using a one-step REINFORCE algorithm. The trained model has increased the speed of motion planning by up to 820 times and improved the success rates of obstacle crossing under harsh conditions, such as low friction and high roughness.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1992년도 추계학술대회논문집
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• pp.54-62
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• 1992

This work has been directed at studying and developing a prototype Computer Aided Design(CAD) tool to be used for planning tendon paths in hand reconstructive surgery. The application of CAD to rehabilitative surgery of the hand is a new field of endeavor. There are currently no existing systems designed to assist the orthopedic surgeon in planning these complex peocedures. Additionally, orthopedic surgeons are not trained in mechanics, kinematics, math modeling, or the use of computers. It was also our intent to study the mechanisms and the efficacy of the application of CAD techniques to this important aspect of hand surgery. The following advances are reported here: Interactive 3D tendon path definition tools., Software to calculate tendon excursion from an arbitrary tendon path crossing any number of joints., A model to interactively compute and display the foirces in muscle and tendon., A workstation environment to help surgeons evaluate the consequences of a simulated tendon transfer operation when a tendon is lengthened, rerouted, or reattached in a mew location., It also has been one of the primary concerns in this work that an interactive graphical surgical workstation must present a natural, user-friendly environment to the orthopedic durgeon user. The surgical workstation must ultimately aid the surgeon in helping his patient or in doing his work more efficiently or more reliably.

• 전자공학회논문지S
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• 제35S권10호
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• pp.64-76
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• 1998

본 논문에서 4-구륜 2-자유도 이동 로보트의 체계적인 동적 모델링과 경로설계 및 추적 알고리즘을 제안한다. 실시간에서 이동 로보트의 위치 측정을 위해 관성측정장치중의 3가지 요소를 이용한다. 이러한 장치들은 지구의 회전속도 및 중력가속도 등의 여러 요인으로 인해 초기 오차를 가진다. 그래서 초기오차 모델을 유도하고, 실제 데이터와 유도된 모델의 추정 데이터의 확률적 특성을 분석 ${\cdot}$ 비교하여 적합도를 판정하여 사용한다. 관성측정장치의 동작특성은 오차모델과 칼만 필터와 연계된 경우와 배제된 일반적인 경우와 비교한다. 모의실험 결과들은 제안된 경로설계 및 추적 알고리즘이 기존의 방식과 비교하여 보다 유용함을 입증한다.

• 로봇학회논문지
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• 제19권1호
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• pp.130-138
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• 2024

High-precision 3D Object Detection is a crucial component within autonomous driving systems, with far-reaching implications for subsequent tasks like multi-object tracking and path planning. In this paper, we propose a novel approach designed to enhance the performance of 3D Object Detection, especially in heading angle estimation by employing a moving object segmentation technique. Our method starts with extracting point-wise moving labels via a process of moving object segmentation. Subsequently, these labels are integrated into the LiDAR Pointcloud data and integrated data is used as inputs for 3D Object Detection. We conducted an extensive evaluation of our approach using the KITTI-road dataset and achieved notably superior performance, particularly in terms of AOS, a pivotal metric for assessing the precision of 3D Object Detection. Our findings not only underscore the positive impact of our proposed method on the advancement of detection performance in lidar-based 3D Object Detection methods, but also suggest substantial potential in augmenting the overall perception task capabilities of autonomous driving systems.

• 한국지능시스템학회논문지
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• 제20권4호
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• pp.489-496
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• 2010

본 논문은 3D 환경에서의 스웜시스템을 위한 자기조직화 방법을 제시한다. 스웜 시스템의 자기조직화를 위하여 인력과 척력을 이용하는 인공 포텐셜 함수(Artificial Potential Function, 이하 APF)를 사용하였다. 제안된 연구에서는 2D 환경에서 자기조직화를 위해 사용되어왔던 다양한 포텐셜들을 3D 환경에 맞게 확장 설계한다. 지면이나 수면 등의 경계면을 가지는 3D 환경의 특성을 고려하여 지면 포텐셜(Ground Potential)을 제안한다. 지면 포텐셜을 고려하지 않았을 때와 고려할 때의 비교 결과를 통해 지면 포텐셜의 필요성과 효과를 보여준다. 마지막으로, 다양한 시뮬레이션 결과를 통해 3D 환경에서 확장된 인공포텐셜과 그 성질의 효율성을 보여준다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.627-634
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• 1989

A collision-free trajectory planning algorithm using the iterative learning concept is proposed for dual robot arms in a 3-D workspace to accurately follow their specified paths with constant velocities. Specifically, a collision-free trajectory minimizing the trajectory error is obtained first by employing the linear programming technique. Then the total operating time is iteratively adjusted based on the maximum trajectory error of the previous iteration so that the collision-free trajectory has no deviation from the specified path and also the operating time is near-minimal.

• 대한임베디드공학회논문지
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• 제10권3호
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• pp.179-188
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• 2015

We propose obstacle classification method based on 2D LIDAR(Light Detecting and Ranging) database. The existing obstacle classification method based on 2D LIDAR, has an advantage in terms of accuracy and shorter calculation time. However, it was difficult to classifier the type of obstacle and therefore accurate path planning was not possible. In order to overcome this problem, a method of classifying obstacle type based on width data of obstacle was proposed. However, width data was not sufficient to improve accuracy. In this paper, database was established by width, intensity, variance of range, variance of intensity data. The first classification was processed by the width data, and the second classification was processed by the intensity data, and the third classification was processed by the variance of range, intensity data. The classification was processed by comparing to database, and the result of obstacle classification was determined by finding the one with highest similarity values. An experiment using an actual autonomous vehicle under real environment shows that calculation time declined in comparison to 3D LIDAR and it was possible to classify obstacle using single 2D LIDAR.

• 한국정보과학회논문지:소프트웨어및응용
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• 제37권8호
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• pp.641-646
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• 2010

스테레오 카메라를 갖춘 인간형 로봇이 자율적으로 주변 상황을 인지하면서 목적지까지의 경로를 실시간으로 생성 및 수정하는 간단한 알고리즘을 제시한다. 특징점들을 시각적 이미지에서 추출함으로써 주위의 장애물들을 인지한다. 인간형 로봇의 뒤뚱거리는 보행 움직임을 모델링함으로써 로봇의 중심부 기준에서의 실제 경로를 유추하여 계획된 경로와 비교함으로써 시각적 피드백 제어를 구현하고 성공적인 네비게이션을 수행한다. 실제 인간형 로봇의 네비게이션 실험을 통해 제안된 알고리즘의 가능성을 입증한다.

• 한국항공우주학회지
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• 제49권12호
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• pp.989-996
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• 2021

배터리를 동력원으로 사용하는 무인항공기의 경우 배터리 용량이 한정적이기 때문에 임무 수행에 제약이 발생할 수 있다. 이를 최소화하기 위해 임무 지역으로 이동하는 동안 소모되는 배터리를 최소화 하는 것이 중요하다. 또한 임무 계획 단계에서 배터리 소모량 예측 모델을 이용하여 임무 수행 가능성을 사전에 판단할 수 있으며 복귀 시점 선정에 기준이 될 수 있다. 본 논문에서는 3차원 공간에서 환경 요소를 반영한 배터리 사용량 예측 모델을 제안한다. 무인항공기의 비행 기하 관계에 따라 요구 동력을 산출하고 이를 통해 배터리 사용량을 예측하였으며 기존에 제안된 배터리 사용량 예측 기법과 비교를 통해 검증한다. 또한 이를 목적함수로 하여 배터리 사용량을 최소화 하는 비행경로를 생성하고 최단 거리를 목적함수로 하였을 때의 결과와 비교하였다.

• 한국의학물리학회지:의학물리
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• 제28권4호
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• pp.144-148
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• 2017

When a high density metallic implant is placed in the path of the proton beam, spatial heterogeneity can be caused due to artifacts in three dimensional (3D) computed tomography (CT) scans. These artifacts result in range uncertainty in dose calculation in treatment planning system (TPS). And this uncertainty may cause significant underdosing to the target volume or overdosing to normal tissue beyond the target. In clinical cases, metal implants must be placed in the beam path in order to preserve organ at risk (OARs) and increase target coverage for tumors. So we should introduce Ti-mesh. In this paper, we measured the lateral dose profile for proton beam using an EBT3 film to confirm dosimetric impact of Ti-mesh when the Ti-mesh plate was placed in the proton beam pathway. The effect of Ti-mesh on the proton beam was investigated by comparing the lateral dose profile calculated from TPS with the film-measured value under the same conditions.