• International Journal of Precision Engineering and Manufacturing
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• 제9권2호
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• pp.3-7
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• 2008

Vibratory conveyors are widely used in industry to transport granular materials and products. A theoretical point mass model for vibratory conveying was studied. The results agreed well with experimental observations. The model theory included the resting, sliding and flight states of the material. Each state was considered separately when determining the equations of motion. For the coefficients of restitution, values of zero for the normal component and 0.8 for the tangential component were found to be appropriate for modeling the collisions of the granular particles with the conveying surface. The vibration angle had a large influence on the mode and rate of transport. There was an optimum vibration angle for a given set of conditions. The optimum vibration angle decreased and was better defined as the coefficient of friction increased. The results suggest the existence of an optimum dimensionless track acceleration (throw number), which does not support general industrial practice in which the track acceleration is limited when the feed cycle becomes erratic and unstable.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.460-465
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• 2002

The nonlinear vibration of the CRT shadow mask is analyzed in consideration of the V-shaped tension distribution and the effect of wire impact damping. The reduced order FEM model of the shadow mask is obtained from dynamic condensation for the mass and stiffness matrices. Damping wire is modeled using the lumped parameter method to effectively describe its contact interactions with the shadow mask. The nonlinear contact-impact model is composed of spring and damper elements, of which parameters are determined from the Hertzian contact theory and the restitution coefficient, respectively. The analysis model of the shadow mask with damping wires is experimentally verified through impact tests of shadow masks performed in a vacuum chamber. Using the validated analysis model of the shadow mask with damping wires, the‘design of experiments’technique is applied to search fur the optimal damping wire configuration so that the vibration attenuation of the shadow mask is maximized.

• 한국소음진동공학회논문집
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• 제12권9호
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• pp.731-737
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• 2002

Nonlinear vibration of the CRT shadow mask with impact damping wires is analyzed in consideration of the mask tension distribution and the effect of wire impact damping. A reduced order FEM model of the shadow mask is obtained from dynamic condensation of the mass and stiffness matrices, and damping wire is modeled using the lumped parameter method to effectively describe its contact interactions with the shadow mask. The nonlinear contact-impact model is composed of spring and damper elements, of which parameters are determined from the Hertzian contact theory and the restitution coefficient, respectively. The analysis model of the shadow mask with damping wires is experimentally verified through impact tests of shadow masks performed in a vacuum chamber.

• Macromolecular Research
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• 제13권5호
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• pp.441-445
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• 2005

Thermoplastic polyurethane elastomer (TPUe) fiber mats were successfully fabricated by electrospinning method. The TPUe fiber mats were subjected to a series of cycling tensile tests to determine the mechanical behavior. The electrospun TPUe fiber mats showed non-linear elastic and inelastic characteristics which may be due to slippage of crossed fiber (non-bonded or physical bonded structure) and breakage of the electro spun fibers at junctions (point-bonded or chemical bonding structure). The scanning electron microscopy (SEM) images demonstrated that the point-bonded structures of fiber mats played an important role in the load-bearing component as determined in loading-unloading component tests, which can be considered to have a force of restitution.

• 한국소음진동공학회논문집
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• 제12권8호
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• pp.639-647
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• 2002

The nonlinear vibration of the thin perforated plate is analyzed in consideration of the V-shaped tension distribution and the effect of wire impact damping. The reduced order FEM model of the tension plate is obtained from dynamic condensation for the mass and stiffness matrices. Tension wire is modeled using the lumped parameter method to effectively describe its contact interactions with the plate. The nonlinear contact-impact model is composed of spring and damper elements, of which parameters are determined from the Hertzian contact theory and the restitution coefficient, respectively. From the evaluation of the computational accuracy and computation time for the deduced impact stiffness and damping coefficient, we determined proper values for the simulation works, accounting for the computational accuracy as well as the computational efficiency. Finally we discussed the results of nonlinear nitration analysis for variations of their design parameters.

• 한국공작기계학회논문집
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• 제17권4호
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• pp.126-132
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• 2008

The vibration and disturbances from operating the compact disk layer have an effect on the play ability. As the excitation sources of the compact disk player, there are the vibration of the motors and gears, impact by mechanical parts and the external excitations. So, most of the compact disk player have a anti-vibrational system, which is included some rubber or oil dampers. In this study, the vibration characteristics of rubber damper which is used home compact disk player are investigated. The materials and shape of rubber damper are changed, and the transmissibility is measured. As a conclusion, the natural frequency is moved to higher frequency and the transmissibility is reduced by the increasing rubber stiffness. In comparison to butyl rubber damper, the transmissibility of silicon damper was increased by larger restitution elasticity. The hollow damper was effective to reduced the transmissibility.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2227-2229
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• 2003

Using the gyro effect, Balance Beam Controller is developed with Samsung Corporation. Balance Beam Controller is possible to control the position of an object in air by controlling the attitude of inner gimbal. But in the unknown load inertia case, even a skilled worker it is not easy to operate a Balance Beam. That is caused by the difficulty to estimate the load inertia. If the amount of the gimbal operation is set excessively with a wrong load estimation, it can often cause accidents. To solve this problem, the control function which is revolving with velocity of the revolution has to be added to developed equipment. In this research, we analyze the characteristics of a Balance Beam(the smaller load inertia, the bigger force of restitution) using the angular velocity sensor, and present constant velocity revolving controller with estimating value of the load using this moving characteristics.

• 드라이브 ㆍ 컨트롤
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• 제19권4호
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• pp.10-18
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• 2022

Air-drop hammer press and counterblow hammer press are widely used power-drop forging hammersemploying different forging blow mechanisms. It is important and necessary to analyze mechanical vibrations of these two different hammers in their forging processes in order to develop high performance forging hammers. In this study, these two forging hammers were mathematically modelled as mass-spring-damper systems. For these two different types of forging hammers, the forging efficiency and mechanical vibrations due to hammer forging blow were theoretically analyzed and compared. The force transmitted to the ground was also determined and compared. Especially, effects of mass ratio and restitution coefficient on forging efficiency were investigated.

• 한국정밀공학회지
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• 제14권4호
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• pp.126-135
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• 1997

A sensorless motion planner which succeeds in grasping a polygonal part firmly into a desired orientation has been developed through the dynamic analysis. The analytical results on the impact process with friction are used for modeling the contact motionduring the parallel-jaw grasp operation, which is com- posed of the pushing and the squeezing process. The developed planner succeeds in grasping a part into a specified orientation in the face of uncertainties of initial position and orientation of the part, motion direction of the finger, and the physical parameters such as the coefficients of friction and restitution. The motion planner has been fully implemented into a viable package on the computer system, and verified experimentally. The motion of parts is recorded using a high-speed video camera, and then compared to the results of the planner and the graphic simulation results that illustrate the simulated motion of the grasp operation.

• KDI Journal of Economic Policy
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• 제34권3호
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• pp.1-29
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• 2012

본 연구에서는 혁신도시지역과 그 주변지역의 지가 데이터를 바탕으로 혁신도시사업에 따라 토지가격이 어느 시점부터 어느 정도 변동했는지 살펴보았고, 이를 통해 현행 제도가 개발이익의 배제원칙에 잘 부합하지 않음을 밝히는 한편, 현행 제도를 개발이익의 배제원칙에 보다 부합하도록 개선하기 위한 방안들을 모색하였다. 우선 혁신도시지역과 그 주변지역의 지가 데이터를 분석해 보면, 대부분의 혁신도시지역의 지가가 2005년부터 그 주변지역들에 비해 통계적으로 유의하게 상승하기 시작하였음을 알 수 있다. 즉, 이 시기부터 혁신도시사업과 관련한 정보가 지가에 반영되기 시작하였다고 볼 수 있는데, 이와 같이 혁신도시사업 관련 정보가 반영된 지가를 바탕으로 실제 보상액을 산정하면 개발이익의 배제원칙과는 괴리가 생기게 된다. 그러나 토지보상법 제70조에 따른 보상액 산정의 기준지가는 2007년 1월 1일 공시된 공시지가이며, 또한 실제로도 이러한 기준을 적용하여 보상이 진행되었다. 즉, 2005년부터 2006년 말까지 개발 정보가 해당 혁신도시 지가에 반영되었음에도 불구하고 이를 배제하기 위한 제도적 장치 및 노력 없이 보상이 진행되었다. 이러한 문제들을 해결하기 위해 본 연구에서는 크게 두 가지 방안을 제안하고 있다. 첫째, 토지보상법 제70조 제5항에서 소급적용할 수 있는 공시지가의 한계를 두지 말고, 대신 개발이익이 반영되지 않았다고 판단되는 가장 최근의 공시지가를 기준시가로 적용하도록 변경하는 것이 필요하다고 판단된다. 이렇게 정해진 기준시가를 바탕으로 가격인정시점까지의 통상적인 평균 물가상승률, 평균 지가상승률 등을 바탕으로 보상액을 보정한다면 개발이익 배제의 원칙에 보다 부합할 것이다. 둘째, 개발이익이 지가에 반영되었다고 판단하는 기준을 하위 법령에 명시적으로 포함시킬 필요가 있다. 현행 제도하에서는 수용보상액 산정 시 개발이익 반영 여부에 대한 평가자의 자의적인 해석이 포함될 가능성이 크다. 따라서 본 연구에서의 학술적 연구 결과와 현행 토지보상평가지침(감정평가협회) 등의 기준 등을 참고하여 개발이익 반영 여부를 판단하는 기준을 개선할 필요가 있다.