• Journal of Drive and Control
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• v.20 no.3
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• pp.42-49
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• 2023

In this study, the safety of fastening device for the agricultural by-product collector was evaluated according to the driving ground conditions by deriving the stress, static safety factor, and fatigue life using dynamic simulation. A 3D modeling of agricultural by-product collector was carried out, and simulation model was developed by applying the material properties. As a result of dynamic simulation, the magnitude of the maximum stress generated in the fastening device was the highest when driving on the flat off-road, followed by sloped pave-road and flat pave-road. Static safety factor and fatigue life were the highest when driving on the flat pave-road, followed by sloped pave-road and flat off-road. The safety of fastening device was confirmed that static safety factor was more than 1.0 and service life exceeded 9 years in all driving ground conditions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.3
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• pp.110-115
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• 2005

Driving performance is affected by a steering mechanism and characteristics of the ground at off-road skateboarding. In order to drive on off-road, it is necessary off-road wheel and high performance steering mechanism to adapt on various configuration of the ground. In this paper, design factors are studied to affect to steering radius such as inclination angle of a king-bolt, distance of a wheel axle, and rolling angle of a deck plate. A steering system is adhered to inclination face of the deck plate. And, inclination angle is existed between the king-bolt and the flat face of the deck plate. Therefore, the wheel axle of the steering system can be steered by control of the rolling angle of the deck plate.

• The Journal of Korea Robotics Society
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• v.5 no.3
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• pp.270-277
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• 2010

Various robot platforms have been designed and developed to perform given tasks in a hazardous environment for the purpose of surveillance, reconnaissance, search and rescue, and etc. We have considered a terrain adaptive hybrid robot platform which is equipped with rapid navigation on flat floors and good performance on overcoming stairs or obstacles. Since our special consideration is posed to its flexibility for real application, we devised a design of a transformable robot structure which consists of an ordinary wheeled structure to navigate fast on flat floor and a variable tracked structure to climb stairs effectively. Especially, track arms installed in front side, rear side, and mid side are used for navigation mode transition between flatland navigation and stairs climbing. The mode transition is determined and implemented by adaptive driving mode control of mobile robot. The wheel and track hybrid mobile platform apparatus applied off-road driving mechanism for various professional service robots is verified through experiments for navigation performance in real and test-bed environment.

• Journal of Drive and Control
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• v.12 no.4
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• pp.35-40
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• 2015

A gas spring provides support force for lifting, positioning, lowering, and counterbalancing weights. It offers a wide range of reaction force with a flat force characteristic, simple mounting, compact size, speed controlled damping, and cushioned end motion. The most common usage is as a support on a horizontally hinged automotive tail gate. However, its versatility and ease of use has been applied in many other industrial applications ranging from office equipment to off-road vehicles. The cylinder of a gas spring is filled with compressed nitrogen gas, which is applied with equal pressure on both sides of the piston. The surface area of the rod side of the piston is smaller than the opposite side, producing a pushing force. The magnitude of the reaction force is determined by the cross-sectional area of the piston rod and the internal pressure inside the cylinder. The reaction force is influenced by many design parameters such as initial chamber volume, diameter ratio, etc. In this paper, we investigated the reaction force characteristics and carried out parameter sensitivity analysis for the design parameters of a gas spring.

• The Journal of Korea Robotics Society
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• v.17 no.4
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• pp.500-507
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• 2022

In this study, a motion planning method based on the integer representation of contact status between wheels and the ground is proposed for planning swing motion of a 6×6 wheel-legged robot to cross large obstacles and gaps. Wheel-legged robots can drive on a flat road by wheels and overcome large obstacles by legs. Autonomously crossing large obstacles requires the robot to perform complex motion planning of multi-contacts and wheel-rolling at the same time. The lift-off and touch-down status of wheels and the trajectories of legs should be carefully planned to avoid collision between the robot body and the obstacle. To address this issue, we propose a planning method for swing motion of robot legs. It combines an integer representation of discrete contact status and a trajectory optimization based on the direct collocation method, which results in a mixed-integer nonlinear programming (MINLP) problem. The planned motion is used to control the joint angles of the articulated legs. The proposed method is verified by the MuJoCo simulation and shows that over 95% and 83% success rate when the height of vertical obstacles and the length of gaps are equal to or less than 1.68 times of the wheel radius and 1.44 times of the wheel diameter, respectively.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.4
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• pp.1-8
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• 2002

The place of South Weol Dynastys authorities exhumed in the region of KangChoWu, China lies adjacent to a stone ditch through which water streams crookedly, and a dark trough of stone pond in the north side. There is a sharply curved stone ditch and a crescent-shaped water entrance made by stones. The place was separated by using stone columns and stone walls. There is a beam of ditch, a crooked entrance, a flat bridge of slate, a stepping-stone, a sluice gate, and a crooked corridor. There are big and small artificial islands, and reinforcing stone drainage way in the palace pond recently exhumed at the building site for the pavilion of Hwang-Yong Temple in Kuhwang-Dong, Gyeongju city, Korea. There are four facilities assumed to be entrance and exits at four corners and an open space on which gravel was spread extensively. A narrow road and a middle road with indefinite curves at the south of Asukakyoseki exhumed by the first, second and third and two stone buckets which one is to fill with water and the other is to drain water off like fountain are there, and besides wave protecting dam and north pond and the part that water pass were excavated. Palace ponds that were extensively distributed at old residential cities are a general phenomenon of countries in eastern Asia. Anap pond of Silla and Gungnam pond of Baekje were in Kroea. We believe that Asutnkyoseki is on the extension. Although more investigations in the background of thought and the genealogical relation about the palace pond are required, it seems that an idea was surely received from China.