• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.81-88
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• 2001

To study the influence of the shape of contacting bodies (especially the end profile) on slip regime, wear test is conducted in the case of the contact between tube and support. Two different end profiles of the support are used such as truncated wedge and rounded punch. During the test, 10, 30 and 50 N are applied as normal force and slip displacement varies between 10-200 $\mu\textrm{m}$. The tube and the support specimens are made of Zircaloy-4 and a specially designed wear tester is used. Tests are carried out in air at room temperature. Wear on the tube is examined by measuring microscope. Partial and gross slip regimes are classified from the observed wear shape. Surface roughness tester is also used to measure the wear depth and contour, from which wear volume is evaluated. The transition from partial to gross slip is also investigated by investigating the considerable increase of wear volume. From the result, the boundary between the partial and the gross slip is newly determined in the conventional fretting map for the present specific contact configuration. Since the transition is related with the amount of energy dissipation from the contact surface so is wear, it is regarded that wear can be restrained by designing a proper shape of support.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1424-1429
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• 2004

In this paper a mathematical framework for deriving acceleration bounds from given joint torque limits of multiple cooperating robots are described. Especially when the different frictional contacts for every contact are assumed and the torque limits are given in 2-norm sense, we show that the resultant geometrical configuration for the acceleration is composed of corresponding parts of ellipsoids. Since the frictional forces at the contacts are proportional to the normal squeezing forces, the key points of the work includes how to determine internal forces exerted by each robot in order not to cause slip at the contacts while the object is carried by external forces. A set of examples composed of two robot systems are shown with point-contact-with-friction model and insufficient or proper degree of freedom robots.

• 대한기계학회논문집B
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• 제32권2호
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• pp.149-157
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• 2008

During CVD process of semiconductor wafer fabrication, maintaining the uniformity of temperature distribution at wafer top surface is one of the key factors affecting the quality of final products. Effect of contact conductance between wafer and hot plate on predicted temperature of wafer was investigated. The validity of opaque wafer assumption was also examined by comparing the predicted results with Discrete Ordinate solutions accounting for semitransparent radiative characteristics of silicon. As the contact conductance increases predicted wafer temperature increases and the differences between maximum and minimum temperatures within wafer and between wafer and hot plate top surface temperatures decrease. The opaque assumption always overpredicted the wafer temperature compared to semitransparent calculation. The influences of surrounding reactor inner wall temperature and hot plate configuration are then discussed.

• Structural Engineering and Mechanics
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• 제28권2호
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• pp.239-257
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• 2008

Double-sided punched metal plate timber fasteners present projections on both sides, which offer improved joint fire resistance and better joint aesthetics. In this paper, 3-D nonlinear finite element models were developed to simulate double-sided nail plate fastener timber joints. The models, incorporating orthotropic elasticity, Hill's yield criterion and elasto-plasticity and contact algorithms, are capable of simulating complex contact between the tooth and the timber and between the base plate and the timber in a fastener. Using validated models, parametric studies of the double-sided nail plate joints was undertaken to cover the tooth length and the tooth width. Optimal configuration was assumed to have been attained when increase in nail plate tooth width did not result in a raise in joint capacity, in conjunction with the optimum tooth length. This paper presents the first attempt to model and optimise tooth profile of double-sided nail plate fastener timber joints, which offers rational designs of such fasteners.

• 제어로봇시스템학회논문지
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• 제8권10호
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• pp.867-873
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• 2002

We have designed and fabricated the slidacs type automatic voltage regulator(SVR) that is able to control the output voltage continuously according to load variation. Especially, the frictions between the surface of contact of the slidacs coils and the output wire moving shaft arc reduced by modifying the mechanical configuration of surface of contact of slidacs from the conventional sliding one into the proposed rotary one composed of cylindrical bearing. Thus, SVR using cylindrical bearing proposed in this study has less noise than the conventional one owing to the reduction of friction, and its breakdown ratio caused by the abrasion of contact materials is reduced as well. We have designed U motor driving circuit for controlling the output wire moving shaft, and introduced the digital control method using the pulse width modulation(PWM) output for controlling DC motor.

• 한국초전도ㆍ저온공학회논문지
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• 제15권4호
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• pp.59-62
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• 2013

The conductive link is used as a cooling medium between a cryocooler and magnet in a cryogen-free superconducting magnet system. The low temperature superconducting (LTS) magnet has one solenoidal configuration with a metal former which has a 52 mm room temperature bore. The superconducting coil is installed in the cryostat maintaining high vacuum and cooled by a two-stage cryocooler. In order to maintain the operating temperature of magnet at the designed level, the cold head temperature of the cryocooler must be lower so that heat can be removed from the superconducting coil. Also, temperature difference is occurred between the magnet and cryocooler and its magnitude is dependent upon the contact resistance at the interfacial surface between metals in the conductive link. In the paper, the performance of the LTS magnet is investigated with respect to the conductive link between the magnet former and the cold head of the cryocooler. The effects of the contact pressure and interfacial materials on the temperature distribution along the conductive link are also presented.

• 대한기계학회논문집A
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• 제30권12호
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• pp.1596-1602
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• 2006

In this paper, a hybrid sensor is proposed that has two capabilities: the first is to sense longitudinal or flexural transient vibration signals selectively which are transmitted along the target shaft, and the second to measure the rotating speed of the shaft. All measurements are made in a non-contact manner since this sensor uses magnetostriction as its measuring principle. The signal selection between two vibration modes requires only electrical switching operations and the switching between these two sensing capabilities-vibrations and rotational speed-are accomplished by a very simple mechanical operation. To verify the capabilities of the proposed sensor, a prototype sensor is fabricated and the experiments are made. The results show this sensor can embody two sensing capabilities in one sensor configuration.

• Tribology and Lubricants
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• 제11권4호
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• pp.35-44
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• 1995

Within the practical ranges of speed and load, the formation of transfer films and the consequent effects on the friction and wear behavior of ceramic materials during repeated pass sliding contact were studied. These tests were done using $Al_{2}O_{3}$, SiC and $Si_{3}N_{4}$ with the cylinder-on-flat test configuration. The three pairings behaved differently, even if some wear mechanisms were common to the three systems. The $Al_{2}O_{3}$ pair showed the least wear in overall conditions, followed by the $Si_{3}N_{4}$ pair in harder sliding conditions. The wear of SiC was very high at severe loading. In case of $AL_{2}O_{3}$ and $Si_{3}N_{4}$, the transfer film, whenever formed, is strongly attached, enough to resist being wiped off by the slider. As a consequence, the formation of this f'fim leads to a decrease in the wear rate because of the protecting role of the film. The presence of the film at the contact interface also results in high friction. Also, the wear rate of each ceramics is related to the frictional power provided by load, speed and friction.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.65.5-65
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• 2001

In this study, we have designed and fabricated the slidacs type automatic voltage regulator(AVR) that is able to control the output voltage continuously according to road variation. Especially, the frictions between the surface of contact of the slidacs coils and the output wire moving rod are reduced by transforming the mechanical configuration of surface of contact of slidacs from the conventional sliding one into the proposed rotary one composed of cylindrical bearing. Thus, the slidacs type AVR using cylindrical bearing proposed in this study has less noise than conventional one owing to the reduction of frictions, and its breakdown ratio caused by the abrasion of contact materials is reduced. Furthermore, ...

• 대한건축학회논문집:계획계
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• 제35권3호
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• pp.3-12
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• 2019

Since offline contact becomes a strong differentiator as online market expands, the shopping mall calls for more complex and diverse tenant combinations and deployment plan strategies. There is, however, few practical research and causal verification of Tenant Mix, i.e., the combination and placement of tenant and users' behavior, has been conducted which is a key factor in spatial configuration. In practice, Tenant Mix is limited in prediction of consumption behavior of customers by the MD planners's experience and depends only on qualitative arbitrary plan. The purpose of this study is to find out the interrelationship between the spatial configuration and the users' behavior of Tenant Mix in shopping mall, and to present an objective basis in MD planning. According to the analysis, it was possible to know that there are differences in the relationship between the spatial configuration and the users' behavior dependent on the Tenant Mix, which is the space planning of shopping mall. It was also possible to find out the characteristics and differences in the users' behavior which is dependent on the spatial configuration for each tenant. Through this study, it was possible to know the impact of space organization on the users' behavior and the interrelationship between the use's behavior and spatial configuration by tenant together with their characteristics. We prove that the current MD planning has limitation due to lack of objective research on the combination and arrangement of space in the commercial space and only done empirically. This analysis can show the practical plan of combination and placement of tenant which is emphasized in complex and larger shopping malls, and contribute to the revitalization of shopping mall by better use of tenant.