• 소성∙가공
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• 제17권3호
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• pp.203-209
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• 2008

In this paper, experimental investigation has been performed to analyze the forming process of toothed or serrated sheets, which is used as strap engaging surface of the seal to secure together overlapping portions of steel or plastic strapping ligature. Serration formed on the strap engaging surface of the seal prevent from relative slipping between overlapping ligatures after closing the seal. The geometry of tooth on the strap engaging surface is directly related to the quality of securing overlapping ligatures together. Inclined indentation followed by scratching operation has been proposed and applied to the experiments. Punch entry and face angles are selected as process variables to see the influence of these variables on the tooth geometry. Five different punch entry angles have been applied to experiments and three different punch face angles have been selected for each case of punch entry angle. Clay is selected as model material for experiments. Experimental results are summarized in terms of tooth height, tooth width, and aspect ratio such as tooth height to width ratio, respectively.

• 한국정밀공학회지
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• 제12권5호
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• pp.40-45
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• 1995

The kinematical relationship of bevel gearsets lies at the root of the gear design. As the demand on precision bevel gears is increased in the related industries, the kinematic analysis of a pair of sperical involute bevel gears needs to be exactly evaluated for the computer aided design. Pitch cone angles of bevel gearsets have been calculated under the assumption that the geared system is equivalent to a coned roller system without slipping. But this kinematical model involves some errors in the value of the ratio of angular velocity. In this paper, the ratio of the angular velocity is exactly derived, based on the perfect involute tooth surface. Four nonlinear equations representing the kinematical relationships are numerically solved to obtain the pitch and base cone angles. The ratios of angular volocities according to pressure and shaft angles are calculated and compared with those of the approximate gear model.

• 한국전기전자재료학회논문지
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• 제16권12S호
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• pp.1157-1164
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• 2003

This paper shows the results of atomistic modeling for the interaction between spherical nano abrasive and substrate in chemical mechanical polishing processes. Atomistic modeling was achieved from 2-dimensional molecular dynamics simulations using the Lennard-Jones 12-6 potentials. The abrasive dynamics was modeled by three cases, such as slipping, rolling, and rotating. Simulation results showed that the different dynamics of the abrasive results the different features of surfaces. This model can be extended to investigate the 3-dimensional chemical mechanical polishing processes.

• 대한안전경영과학회지
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• 제18권3호
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• pp.81-89
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• 2016

Floor slipperiness is a leading cause in slip and fall accidents which are a major source of occupational injuries in Korea. Researchers have estimated the slip and fall related accidents rank number one or two in number of the injured. The objectives of this study were to find the field contamination effect and improvement countermeasure. Slipping and falling are common accidents in large public facilities, especially facility which vulnerable adults generally use as like hospital. So, we measured the coefficient of friction of several floors on the floor in hospital, under dry and wet using BOT-3000. The results of the coefficient of friction measurements showed that floor type and surface conditions were all significant factors affecting the coefficient of friction. The most surprising finding of this study was that there were significant friction improvement when the floors were properly cleaned with cleaning equipments.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1990년도 가을 학술발표회 논문집
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• pp.55-60
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• 1990

The objective of this study is to predict the nonlinear behavior of reinforced concrete shear walls, with the reinforcement uniformly distributed, under reversed cyclic loads. This study introduces joint Element Model which formulates the pulling out of rebars, slipping and intrusion of junction planes. The applicability of this study was experimental verfied by specimens SW1, SW2 and SW3 tested by authors, Wall1 by Paulay, SW16 and SW19 by Sheu. In almost specimen, the ratio of analytical to experimental maximum shear stress is within approximately 5%. In case of energy dissipation and maximum drift, the analytical results fully coincide with those of experiment.

• 반도체디스플레이기술학회지
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• 제10권3호
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• pp.49-52
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• 2011

This paper shows the results of classical molecular dynamics modeling for the interaction between spherical nano abrasive and substrate in chemical mechanical polishing processes. Atomistic modeling was achieved from 3-dimensional molecular dynamics simulations using the Morse potential functions for chemical mechanical polishing. The abrasive dynamics was modeled by three cases, such as slipping, rolling, and rotating. Simulation results showed that the different dynamics of the abrasive results the different features of surfaces. The simulation concerning polishing pad, abrasive particles and the substrate has same results.

• 대한인간공학회지
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• 제18권1호
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• pp.25-39
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• 1999

Among older persons falls are the leading cause of death resulting from injury. The research was conducted to investigate the effects of transitional floor surfaces and visual field obstruction on gait mechanisms in the elderly. Ten college students and ten elderly individuals participated in the experiment. The results indicated that walking on transitional floor surfaces and carrying a light load changed the elderly individuals biomechanical parameters of gait mechanisms more significantly than their younger counterparts in terms of slip severity. The result implies that the types of floor material placed in the homes of elderly individuals and in public places should minimize transitional floor surfaces and the elderly individuals should be made aware of the danger of slipping even when carrying a light load.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.591-595
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• 2000

In this paper color coordinate system transformation based visual servo controller has been considered Mobile robot always has a position error and an orientation error resulted from wheel slipping etc.. Even more, the errors have accumulative properties. So feedback from environments is important. In this paper by using color model faster land mark extraction can be achieved. And the global position and the orientation of mobile robot can be known by only two land mark positions in image coordinate system. Finally, the adoption of visual information in path tracking problem makes visual servo control.

• 한국안전학회지
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• 제12권2호
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• pp.146-152
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• 1997

The number of accidents due to slipping, falling and awkward postures are estimated to account for over forty percent of annual industrial accidents in Korea. To prevent such accidents, stability-maintaining capabilities of workers should be understood before any other approach. This research was aimed to analyze capabilities of the workers with the help of yours male students maintaining standing postures on a tiltable stability platform. The experimental result showed that tilting direction, height of pivoting point, and permissible degree of swaying made significant effects on stability-maintaining duration. Besides, humans are more capable of maintaining their standing body postures on a platform tiltable fore and aft rather than or one tiltable sideways. The number of falling or tripping supported this phenomenon. A mechanical and physical discussion on the stability was added.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.525-530
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• 1995

The main objective of this study is to develop a gripper mechanism that can be employed for assembly and removal tasks of a nozzle-dam of steam gererator which is one of the nuclear reactor maintenance process. Brief description of the open-close type gripper mechanism, its postion analysis, and its kinematic amalysis are given. The optimal design of the gripper mechanism with slipping on its two gripping surfaces is considered. As an optimaldesign index, the ratio of the actuator force of prismatic cylinder to gripping load is proposed. Then, based on this index the optimal design synthesis is careied out to identify values of optimal design parameters for the gripper mechanism.