• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2001년도 추계학술대회 논문집
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• pp.233-238
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• 2001

The mechanism design of the interactive emotional robot has been carried out. The two-wheeled inverted pendulum type mechanism was adopted to improve the mobility and make the innate clumsy monoaxial bicycle motion. Even though the system is unstable in itself, it is expected for the robot to move freely in a plane, keeping the upright position only with two wheels. Two motors attached on head can make 4 motion sets, and two motors on the wheels can make 8. Therefore, 32 independent motion sets can be achieved from the robot to communicate the emotions with humans. The motion's equation of the robot was derived based on nonholonomic dynamics, and the necessary power to the wheel's rotational axis was found by simulation.

• 한국광과학회:학술대회논문집
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• 한국광과학회 2005년도 제12회 학술대회 논문초록
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• pp.126-126
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• 2005

• 한국전자통신학회논문지
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• 제17권3호
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• pp.507-514
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• 2022

가정에서 사람을 보조하기 위해 이동과 작업이 모두 가능한 모바일 매니퓰레이터의 필요성이 커지고 있다. 본 논문에서는 크기가 작고 낮은 가격으로 구성할 수 있는 모바일 매니퓰레이터를 개발하기 위해 모바일 로봇에 탑재할 수 있는 소형 매니퓰레이터 시스템을 개발하였다. 개발한 매니퓰레이터는 4자유도를 가지며, 끝단에 그리퍼와 카메라를 부착하여 물체의 인식과 인식한 물체에 대한 작업 수행이 가능하다. 개발한 매니퓰레이터는 수직 방향의 선형 이동이 가능하여 상대적으로 높이 위치한 사람의 손에 물건을 전달하거나 협업을 수행하는 데 유리하다. 개발한 매니퓰레이터의 4자유도 동작을 위한 4개의 액츄에이터를 매니퓰레이터의 베이스에 가깝게 배치하고 매니퓰레이터의 회전 관성을 줄임으로써 매니퓰레이터의 작업 중 안정성을 높이고 모바일 매니퓰레이터의 전복 위험을 낮추었다. 개발한 매니퓰레이터의 끝단에 위치한 카메라에서 RGB 영상을 획득하고 영상처리를 통해 물체를 인식하여 목표한 위치로 옮기는 픽 앤 플레이스 동작을 시험하였으며 로봇의 작업영역(workspace) 내에서 성공적으로 동작함을 확인하였다.

• 대한조선학회논문집
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• 제47권6호
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• pp.843-849
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• 2010

This paper presents definition of symmetry of a ship section where three symmetries are proposed: material, geometric, and load symmetries. Precise terminologies of centroid, moment plane, and neutral axis plane are also defined. It is suggested that force vector equilibrium as well as force equilibrium are necessary condition to determine new position of neutral axis due to translational and rotational mobility. It is also stated that new reference datum of ENMP(elastic neutral moment plane), PNMP(fully plastic moment plane), ENAP(elastic neutral axis plane), and INAP(inelastic neutral moment plane) are required to define asymmetric section properties such as second moment of area, elastic section modulus, yield moment, fully plastic moment, and ultimate moment. Since collision-induced damage and flooding-induced biaxial bending moment produce typical asymmetry of section, the section properties are calculated for a typical VLCC. Geometry asymmetry is determined from ABS and DNV rules and two moment planes of 0/30 degs are assumed for load asymmetry. It is proved that the property reduction ratios directly calculated from second moment of area are usually larger than area reduction ratio. Reduction ratio of ultimate moment capacity shows almost linearly proportional to area reduction ratio. Mobility of elastic and inelastic neutral axis planes is visually provided.

• 한국전자통신학회논문지
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• 제5권4호
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• pp.471-479
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• 2010

홀로노믹 구동 기술은 임의의 방향으로 회전 운동과 병진운동을 동시에 구현 할 수 있다. 이런 이유로 홀로노믹 구동 기술은 모바일 플랫폼의 모션을 만드는데 있어 가치가 있으며, 특히 장애물 있기 쉬운 환경에서 모바일 시스템을 작동의 경우, 조종 가능성이 중요한 문제로 부각되는 로봇과 자동차 분야의 이동 어플리케이션으로써 많은 이점을 가진다. 이 논문에서 다수의 서보 캐스터를 이용하여 홀로노믹 구동 시스템을 구현하는 현실적인 방법에 대해 소개한다. 홀로노믹 동작 구현은 다른 서보-캐스터 동작의 조화를 통해 각각의 서보-캐스터의 구동과 조향을 조절한다. 또한 이 논문에서 작동 상황 요구에 따라 조작방법이 달라지는 알고리즘을 제안한다.

• 제어로봇시스템학회논문지
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• 제14권11호
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• pp.1146-1154
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• 2008

This paper presents a method for the acceleration analysis of multi-legged walking robots in consideration of the frictional ground contact. This method is based on both unified dynamic equation for finding the acceleration of a robot's body and constraint equation for satisfying no-slip condition. After the dynamic equation representing relationship between actuator torques and body acceleration, is derived from the force and acceleration relationship between foot and body's gravity center, the constraint equation is formulated to reconfigure the maximum torque boundaries satisfying no-slip condition from given original actuator torque boundaries. From application of the reconfigured torques to the dynamic equation, interested acceleration boundaries are obtained. The approach based on above two equations, is adapted to the changes of degree-of-freedoms of legs as well as friction of ground. And the method provides the maximum translational and rotational acceleration boundaries of body's center that are achievable in every direction without occurring slipping at the contact points or saturating all actuators. Given the torque limits in infinite normsense, the resultant accelerations are derived as a polytope. From the proposed method, we obtained achievable acceleration boundaries of 4-legged and 6-legged walking robot system successfully.

• 로봇학회논문지
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• 제15권3호
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• pp.221-232
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• 2020

In a four-wheel independent drive platform, four wheels and motors are connected directly, and the rotation of the motors generates the power of the platform. It uses a skid steering system that steers based on the difference in rotational power between wheel motors. The platform can control the speed of each wheel individually and has excellent mobility on dirt roads. However, the difficulty of the straight-running is caused due to torque distribution variation in each wheel's motor, and the direction of rotation of the wheel, and moving direction of the platform, and the difference of the platform's target direction. This paper describes an algorithm to detect the slip generated on each wheel when a four-wheel independent drive platform is traveling in a harsh environment. When the slip is detected, a compensation control algorithm is activated to compensate the torque of the motor mounted on the platform to improve the trajectory tracking performance of the platform. The four-wheel independent drive platform developed for this study verified the algorithm. The wheel slip detection and the compensation control algorithm of the platform are expected to improve the stability of trajectory tracking.

• Structural Engineering and Mechanics
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• 제85권6호
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• pp.825-835
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• 2023

The effective buckling length factor is an important parameter in the elastic buckling analysis of steel structures. The present article aims at developing a new method that allows the determination of the buckling factor values for frames. The novelty of the method is that it considers the interaction between the bracing and the elastic supports for asymmetrical frames in particular. The approach consists in isolating a critical column within the frame and evaluating the rotational and translational stiffness of its restraints to obtain the critical buckling load. This can be achieved by introducing, through a dimensionless parameter 𝜙_i, the effects of coupling between the axial loading and bending stiffness of the columns, on the classical stability functions. Subsequently, comparative, and parametric studies conducted on several frames are presented for assessing the influence of geometry, loading, bracing, and support conditions of the frame columns on the value of the effective buckling length factor K. The results show that the formulas recommended by different approaches can give rather inaccurate values of K, especially in the case of asymmetric frames. The expressions used refer solely to local stiffness distributions, and not to the overall behavior of the structure.

• 로봇학회논문지
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• 제18권3호
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• pp.285-292
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• 2023

Small-scale ground mobile robots can access confined spaces where people or larger robots are unable. As the scale of the robot decreases, the relative size of the environment increases; therefore, maintaining the mobility of the small-scale robot is required. However, small-scale robots have limitations in using a large number of high-performance actuators, powerful computational devices, and a power source. Insects can effectively navigate various terrains in nature with their legged motion. Discrete contact with the ground and the foot enables creatures to traverse irregular surfaces. Inspired by the leg motion of the insect, researchers have developed small-scale robots and they implemented swing and lifting motions of the leg by designing leg linkages that can be adapted to small-scale robots. In this paper, we propose a leg linkage design for insect-inspired small-scale ground mobile robots. To use minimal actuation and reduce the control complexity, we designed a 1-DOF 3-dimensional leg linkage that can generate a proper leg trajectory using one continuous rotational input. We analyzed the kinematics of the proposed leg linkage to investigate the effect of link parameters on the foot trajectory.

• 항공우주시스템공학회지
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• 제16권1호
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• pp.49-55
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• 2022

최근 드론의 역할은 농업∙건설∙물류등의 다양한 영역으로 확대되고 있으며 특히 농업인구가 고령화되는 현 상황에 따라 드론은 노동력 부족 문제를 해결할 효과적인 대안으로 떠오르고 있다. 이에 본 논문에서는 농업 현장에서의 부족한 노동력을 보완하고 높은 위치의 과일도 안전하게 수확할 수 있는 드론 탑재형 과일수확 시스템을 제안한다. 과일수확 시스템은 과일인식 알고리즘과 과일수확 메커니즘으로 구성되어 있다. 과일인식 알고리즘은 딥러닝 기반의 객체탐지 알고리즘인 You Only Look Once를 사용하였고, 가상 시뮬레이션 환경을 구축하여 가능성을 검증하였다. 또한, 하나의 모터로 구동이 가능한 과일수확 메커니즘을 제안하였다. 모터의 회전운동을 기반으로 Scotch yoke을 구동시켜 선형운동으로 변환하여 gripper가 전개된 상태에서 과실에 접근 후 과실을 잡고 돌려 수확하는 메커니즘이다. 제안된 메커니즘에 대한 다물체동역학 해석을 수행하여 구동 가능성을 검증하였다.