• Journal of the Korean Society for Heat Treatment
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• v.20 no.2
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• pp.78-83
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• 2007

CrN coatings were deposited by cathodic arc ion plating method on the SKD11 steel substrates. Atmosphere temperature of $350^{\circ}C$, arc current of 90 A, nitrogen partial pressure of 1.0-5.3 Pa, and negative bias voltage of 30-135 V were selected. The characteristics of microstructure were investigated with XRD. Hardness, adhesion and friction coefficient measured by microhardness tester, scratch tester, and ball on disk tribometer. Microstructures depended on nitrogen partial pressure and bias voltage. The preferred orientation of the films was changed from (200) to (111) with decreasing pressure and increasing bias voltage. Adhesion properties related with microstructure, but microstructure changes slightly influenced on hardness and friction properties. The critical load.($Lc_1$) and hardness of CrN films deposited at 5.3 Pa, -30 V condition were 55 N(HF1), $2157{\pm}47\;Hk_{0.025}$. The friction coefficient were about 0.5 under dry condition.

• Journal of the Korean Vacuum Society
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• v.18 no.2
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• pp.141-146
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• 2009

PLZT ferroelectric thin films were deposited on Pt/Ti/$SiO_2$/Si substrate with $TiO_2$ buffer layer in between by rf magnetron sputtering method. In order to investigate the effect of Ar/$O_2$ partial pressure ratio on the ferroelectric properties of PLZT thin films, PLZT thin films were deposited at various Ar/$O_2$ partial pressure ratio ; 27/1.5 seem, 23/5.5 seem, 21/7.5 seem and 19/9.5 seem. The crystallinities of PLZT thin films were analyzed by XRD. The surface morphology was observed using FE-SEM. The P-E hysteresis loops, the remanent polarization characteristics and the leakage current characteristics were obtained using a Precision LC. The crystallinity and elaborateness of PLZT thin films were decreased as increasing the oxygen partial pressure ratio. And preferred orientation of PLZT thin films changed from (110) plane to (111) plane. The oxygen partial pressure ratio affects the thin film surface morphology and the ferroelectric properties.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.899-902
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• 2004

The molecular reorientations and surface morphologies of rubbed films formed from atactic polystyrene (PS) samples with various molecular weights were investigated in detail. Previously unknown surface topography features were newly discovered in rubbed films, depending on molecular weights: submicroscale groove-like meandering structures composed of fine-grooves like pebbles in tens nanometers are present, oriented perpendicular to the rubbing direction. The vinyl main chains, however, were preferentially reoriented along the rubbing direction and the planes of the phenyl side groups were preferentially reoriented perpendicular to the rubbing direction with para-directions that were positioned nearly normal to the film plane. Nematic liquid crystal (LC) molecules were found to always align on the rubbed PS surfaces along the orientation direction of the submicroscale grooves generated by rubbing.

• Korean Journal of Applied Biomechanics
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• v.20 no.1
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• pp.41-47
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• 2010

The purpose of this study was to evaluate the kinematic effect of upper extremity usage for the scoccer instep kick motion. Ten male university students were recruited as the subjects. Temporal parameters, ball velocity, velocity of CG, angle of segment, angular velocity, and trunk orientation angle were determined for each trial. The results showed that temporal parameters in WU and WORU were significantly less than those found in WOU during pre impact phase. These indicated that no usage of upper extremity may increase excessive setup time in order to improve the accuracy of instep kick. Angle of right knee in WOU at LC was significantly greater than corresponding value for WU since angular momentum contributions of the lower limb were not effectively balanced by contributions of the upper limb. We found that the lower extremity movement was controlled by lateral movement in the trunk as a result of no usage of the upper extremity, resulting in the relatively greater trunk rotation in WOU.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.489-492
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• 2005

We report new polymer stabilized ferroelectric liquid crystal (PSFLC) cells with mechanical stability which is achievable by introducing photospacers in the cells. It was found that the mechanical st ability of the PSFLC cell was effected by introduction of photo spacers. We analyzed the dependence of mechanical stability and memory property on the density of photospacers in the PSFLC cell. The stability and memory properties of PSFLC Cells depending on photospacer density are discussed. 1. Introduction Recently, flexible displays have attracted much attention because they have remarkable advantages: thinner, lighter, non-breakable and conformable features. Flexible displays have various potential applications such as e-book and e-paper displays utilizing the distinct features. E-book and E-paper displays demand very low power consumption, so that bistable memory liquid crystal modes are required in case of flexible plastic LCDs for those application. Three kinds of memory LC modes have been developed; bistable nematic, bistable cholesteric and bistable FLC. Among them SSFLC as one of bistable FLC has big advantages such as low driving voltage, wide view angle and fast response time, SSFLC cells are, however, very weak against mechanical shock. Polymer stabilized FLC (PSFLC) has been developed to overcome the poor mechanical stability of SSFLC. PSFLC was known to have network structure that FLCs are oriented with smectic layer ordering in polymer network. The polymer network stabilizes the FLC orientation, which leads to improvement of mechanical stability of PSFLCD. A lot of studies have been done for the application of PSFLC to flexible $LCDs.^{[1{\sim}12]}$ However, it should be noted that PSFLC does not have sufficient mechanical stability for the particular applications such as smart card LCD, where LCD is highly bendable.Bead spacer was mainly used to maintain cell gap of conventional PSFLCDs. But the spacer density of it is not locally uniform in the cell, so that it is generally difficult that the PSFLCDs with bead spacers show sufficient mechanical stability. In order to more improve the mechanical stability of PSFLCDs, we introduced photospacers into PSFLCDs. In this paper, we describe the improvement of mechanical stability by introducing photospacers into PSFLCDs.