• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.5
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• pp.282-288
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• 2010

Experiment on the surface characteristics of polymer films treated by atmospheric pressure plasma has been conducted. We chose the process parameters as frequency, gas flow, treatment time, and scrutinized the effects of the process parameters on the surface characteristics of polymer materials by measuring the contact angle and examining SEM. As the result, the surface characteristics highly depends on frequency, reaction gas and treatment time. In the case of PC substrate, the contact angle was changed from $83.5^{\circ}$ (before plasma treatment) to $30^{\circ}$ (after plasma treatment) at 30 kHz, CDA 0.6%, and number of repeat 7. In the case of PET substrate, the contact angle change was found from $59^{\circ}$ to $23.5^{\circ}$ at 20 kHz, CDA 0.6%, and number of repeat 7. In the case of EVA substrate, it shows from $84^{\circ}$ to $44.2^{\circ}$ at 30 kHz, CDA 0.6%, and number of repeat 7.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.6
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• pp.495-502
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• 2004

This paper presents the vibration analysis and the performance evaluation of cantilevers with probing tips for non-contact scanning probe microscopy. One of the current issues of the scanning probe microscopy technology is to increase the measurement speed, which is closely tied with the dynamic characteristics of cantilevers. The primary concern in this research is to investigate the relation between the maximum possible speed of non-contact scanning probe microscopy and the dynamic characteristics of cantilevers. First, the finite element analysis is made for the vibration characteristics of various cantilevers in use. The computed natural frequencies of the cantilevers are in good agreement with measured ones. Then, each cantilever is tested with topographic measurement for a standard sample with the scanning speed changed. The performances of cantilevers are analyzed along with the natural frequencies of cantilevers. Experiments are also performed to test the effects of how to attach cantilevers in the piezo-electric actuator. Finally, measurement sensitivity has been analyzed to enhance the performance of scanning probe microscopy.

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.437-443
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• 2005

Controlling the friction between wheel and rail is direct and very effective measures to improve the curving performances of railway trucks, because the curving performances depend much on friction characteristics. Authors have proposed a method, 'friction control', which utilizes friction modifier ($KELTRACK^{TM}$ HPF) with onboard spraying system. With the method, not only friction coefficient, but also friction characteristics can be controlled as expected. In this study, MBD simulation is very valuable tool to foresee the effect of the control in advance of experiment with real car. And the creep characteristics of wheel/rail contact with the friction modifier takes very important role in the simulation. In this paper, authors propose a theoretical model of wheel/rail contact condition considering the creep characteristics of friction modifier, which is derived the application of principle tribological theories.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.610-614
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• 1996

Sealing of lubricat-air mixture in the high performance machining conte is one of most the important characteristics to carry out enhanced lubrication. High speed spindle requires non-contact type of sealing mechanism. Evaluating an optimum seal design to minimize leakage is concerned in the aspect of flow control. Effect of geometry and leakage path are evaluated according to variation of sealing geometry, Velocity, pressure, turbulence intensity of profile is calculated to fina more efficient geometry and variables. This offers a methodological way of enhancement seal design for high speed spindle. The working fluid is regarded as two phases that are mixed flow of oil phase and air phase. It is more reasonable to simulate an oil jet or oil mist type high speed spindle lubrication. Turbulence and compressible flow model are used to evaluate a flow characteristic, This paper arranges a geometry of mostly used non-contact type seal and analyzes leakage characteristics to minimize a leakage on the same sealing area.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.2
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• pp.37-45
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• 2007

We have measured the spectral transmittances of UV blocking soft contact lenses, regular soft contact lenses and regular RGP lenses using the method suggested in ANSI Z80.20 standard. In order to evaluate visible light transmitting and UV blocking characteristics, we have calculated transmittances by integrating over the specific spectral ranges, i.e., visible light, UVA, UVB and UVC. We found that mean transmittances of visible light for all three categories were over 90.0 % which could be considered as within acceptable range for a contact lens. The transmittance of the UVA and UVB radiation for the UV blocking soft lenses except some cases was within UVR (Ultraviolet radiation) transmittance standard. The UV blocking ability of regular soft and RGP lenses was poor as rather expected. These results will be expected to assist clinical opticians and practitioners in utilizing the transmittance characteristics about the contact lens.

• Journal of the Korea Society for Simulation
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• v.27 no.2
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• pp.91-100
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• 2018

Recently, the traditional call center, which has an important role as the customer's primary contact point, has been transformed into the omni-channel contact center which supports an additional variety of access channels in addition to phone calls in order to improve customer accessibility and convenience. The omni-channel contact center has agents on each channel which are vital in determining the response rate and waiting time for the customer. In traditional call centers, agents can be assigned to a call based on the characteristics of the call, however in omni-channel contact centers, the characteristics of issues vary and come in through multiple channels, each with their own characteristics, making it difficult to assign the appropriate agent for the issue. Customers must also be processed at the same time, adding an additional layer of complexity to the issue. This paper analyzes and simulates an omni-channel contact center that accommodates email, chat, voice calls and video consultation, and investigates how to optimize the allocation of agents.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1627-1633
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• 2011

Injection molds are generally fabricated by assembling a number of plates in which the core and cavity components are assembled. This assembled structure has a number of contact interfaces where the heat transfer characteristics are affected by thermal contact resistance. In previous studies, numerical approaches were investigated to predict the effect of thermal contact resistance on the temperature distribution of injection molds. In this study, thermal-fluid coupled numerical analyses are performed to take into account the thermal contact effect on the numerical evaluation of the mold filling characteristics. Comparisons with experimental results show that the proposed coupled analysis provides more reliable results than the conventional analyses in predicting the mold filling characteristics by taking into account the effect of thermal contact resistance inside the injection mold assembly.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.10
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• pp.1242-1251
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• 2011

This study investigates the effect of mixed characteristics of oily soil such as mixed ratio, polarity of oily soil on contact angle of fabric, removal of oily and particulate soil from PET fabric in oily/particulate soil mixed system. The contact angle of fabric in the surfactant solution with suspended oily soil was examined as a fundamental environment of detergency of soil from fabrics. Detergency was investigated as function of mixed ratios of oily/ particulate soil, type of oily soil, surfactants concentration, surfactant type and temperature of detergency in surfactant solution. The contact angle of fabric in surfactant solution sharply increased with mixing nonpolar oily soil; in addition, the contact angle slightly increased with increasing contents of oily soil and decreased with increasing surfactant concentration. The removal of oily and particulate soil from fabric was higher in the solution mixed with polar versus nonpolar oily soil. The detergency increased with increasing surfactant concentration and the increased temperature of surfactants solution that were relatively improved in NPE compared to DBS solutions, The results indicated that the detergency of oily and particulate soil showed a similar trend in oily/ particulate mixed soil systems. The general contact angle of fabric was well related with the detergency of oily and particulate soil in oily/particulate mixed soil system, therefore, the primary factor determining the detergency of soil in oily/particulate mixed soil system may be the contact angle of fabric caused by wettability.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.895-902
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• 1999

This paper deals with a numerical study of the tribological contact stress distributions of elastomeric lip seals for oscillating shafts when the sealing interference and band width between the lip ease or contact seals and the shaft are present. Using the finite element method the contact stress and band width of scraper seals are analyzed for the sealing interference including some nonlinearities such as geometrical nonlinearity, material nonlinearity and nonlinear contact boundary condition. The FEM results showed that the contact stress concentrated on the contacting lip zone between the contacting edge of lip and the shaft for the increased interference. In double lip scraper seals, ole maximum contact stress of the dust lip, which is used to exclude foreign contaminants is six times higher than that of the primary sealing lip, which is used to contain lubricants.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.178-182
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• 1991

Contact resistance and contact leakage current of the $Al/TiSi_2/Si$ system are investigated for $N^+\;and\;P^+$ junctions. Titanium disilicide is one of the most common silicides because of its thermal stability, ability, to form selective formation and low resistivity. In this paper, the effect of RTA temperature and Junction implant dose are characterized. The $TiSi_2$ contact resistance to $N^+$ silicon is lower than that of Al to $N^+$ silicon, but $TiSi_2$ of contact resistance to $P^+$ silicon is higher than that of Al to $P^+$ silicon. The $TiSi_2$ of contact leakage current to $N^+\;and\;P^+$ silicon is similar to that of Al contact.