• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.487-488
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• 2008

• Korean Journal of Veterinary Research
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• v.60 no.3
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• pp.145-153
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• 2020

This study aimed to evaluate the effects of a bioabsorbable bone hemostatic agent comprising poly (ethylene glycol-propylene glycol) copolymers (PEG-PPG) on hemostasis and osteogenesis. Bilateral 3 mm diameter calvarial defects were created in 99 male Sprague-Dawley rats. The defects were filled with PEG-PPG or bone wax. The defects of control group were left unfilled. Virtual autopsy was performed to evaluate bioabsorption. The calvaria were subjected to x-ray microtomography (microCT) and histological examination. Bone volume fraction (BV/TV) and bone mineral density (BMD) were measured using microCT; furthermore, white blood cell count and histological examination were performed. After application of PEG-PPG and bone wax, immediate hemostasis was achieved. Autopsy revealed that PEG-PPG disappeared within 48 h at the application site; in contrast, bone wax remained until 12 weeks. The PEG-PPG and control groups showed significantly more osteogenesis than the bone wax group with respect to BV/TV and BMD at 3, 6, and 12 weeks (p < 0.05). Histology revealed that the bone wax group exhibited little bone formation with inflammation. In contrast, PEG-PPG and control groups showed significantly more qualitative osteogenesis than the bone wax group (p < 0.01). In conclusion, PEG-PPG showed immediate hemostasis and was absorbed to allow progressive osteogenesis.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.103.4-103
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• 2001

This paper presents a scaled teleoperation scheme for 3-D microassembly on the experimental microassembly workcell. A workspace mapping between a master and a slave microrobot system is presented to teleoperatively control the microrobot system for microassembly such as peg-in-hole task. Based on this result, a scaling factor is designed and applied to the teleoperated micromanipulation for peg-in-hole task in a mesoscale. Using 3-D virtual simulator, the workspace of microrobot system, and the working path trajectory for microassembly is visually represented. The proposed method is validated through the execution of 3-D microassembly such as peg-in-hole task on the experimental microassembly workcell. The proposed method in the developed ...

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.992-995
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• 2003

A haptic device operated by the user's hand can receive information on position and orientation of the hand and display force and moment generated in the virtual environment to the hand. For realistic haptic display, the detailed information on collision between objects is necessary. In the past, the point-based graphic environment has been used in which the end effector of a haptic device was represented as a point and the interaction of this point with the virtual environment was investigated. In this paper, the shape-based graphic environment is proposed in which the interaction of the shape with the environment is considered to analyze collision or contact more accurately. To this end. the so-called Gilbert-Johnson-Keerthi (GJK) algorithm is adopted to compute collision points and collision instants between two shapes in the 3-D space. The 5- DOF haptic hand controller is used with the GJK algorithm to demonstrate a peg-in-hole operation in the virtual environment in conjunction with a haptic device. It is shown from various experiments that the shape-based representation with the GJK algorithm can provide more realistic haptic display for peg-in-hole operations.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.340-345
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• 1998

A virtual reality system is implemented for the operator supervising a robot's operation at a remote site. For this implementation, a two D.O.F force-reflective joystick is designed to reflect the force/torque measured at the end of robotic manipulator and to generate the motion command for the robot by the operator using this joystick. In addition, the visual information that is captured by a CCD camera, is transmitted to the remote operator and is displayed on a CRT monitor. The operator who is holding the force reflective joystick and watching the CRT monitor can resolve unexpected problems that the robot confronts with. That is, the robot performs the tasks autonomously unless it confronts with unexpected events that can be resolved by only the operator. To demonstrate the feasibility of this system, a remote peg-in-hole operation is implemented and the experimental data are shown.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3876-3881
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• 2012

In typical master/slave teleoperation systems, a human operator generally manipulates the master to control the slave through the visual information like camera image. However, the operator may get into trouble due to the limited visual information depending on the camera positions and the delay on the visual information because of low communication bandwidth. To cope with this inherit problem in the camera-based teleoperation system, this paper presents a teleoperation system using a reconstructed graphic model instead of the camera image. The proposed teleoperation system consists of a robot control module, a master module using a force-reflective joystick, and a graphic user interface (GUI) module. The graphic user interface module provides the operator with a 3D model reconstructed using a small set of sensing data received from the remote site. The proposed teleoperation system is evaluated through a peg-in-hole assembly task.

• Journal of Forest and Environmental Science
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• v.34 no.3
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• pp.224-234
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• 2018

An efficient method to select drought tolerant Korean native plants using in vitro culture system was established in this study. While the plant growths and root inductions of each plant were proportionately affected by concentrations of mannitol on in vitro culturing seven plant species to test tolerance to osmotic stress, growth index (GI) and number of root induction of Chrysanthemi zawadskii var. latilobum and Dianthus chinensis var. semperflorens plantlets were higher than the others in 125mM mannitol. In test with polyethylene glycol (PEG), plantlets of C. zawadskii var. latilobum and D. chinensis var. semperflorens showed higher GI and number of root induction than the others in 33.3mM. On testing whether the well grown plants under osmotic stress are tolerant to virtual drought stress, there were significant differences in the withering rates of C. zawadskii var. latilobum and D. chinensis and those of were Aster yomena and Centaurea cyanus after 12 days without watering. It was found that significantly lower stomata numbers were shown in both drought tolerant plants than the sensitive plants. Averages of the stomata circumferences and the stomata area in the plantlets of the tolerant species were larger than those of the sensitive plants D. chinensis var. semperflorens showed the lowest transpiration level per unit area. The highest stomatal area per unit area was found in C. zawadskii, followed by D. chinensis var. semperflorens, Aster yomena and C. cyanus. In conclusion, C. zawadskii var. latilobum and D. chinensis var. semperflorens were more tolerant to drought than other two species. Furthermore in vitro selection was successfully used to screen drought tolerance species of native plant species.