• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.5
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• pp.300-305
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• 2015

$WO_3$, $SiO_2$, and $TiO_2$ films with hydrophilic property are deposited by rf-magnetron sputtering. Their wettability is strongly depends on the presence or absence of the oxygen plasma etching on the glass substrates. The $TiO_2$ film of 50 nm-thick on the plasma etched glass shows a water contact angle (WCA) below $5^{\circ}$ which means a super-hydrophilic surface. However, WCA values are gradually degraded when the films are exposed under atmosphere, especially $WO_3$. In order to improve hydrophilic property, the degraded films can be again recovered by UV illumination for 10 sec using UV-light and the $TiO_2$ film shows a super-hydrophilic surface about $3^{\circ}$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.1-11
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• 1997

Austomated visual inspection(AVI) capability has become an important key component in the automated manufacturing system. In such a visual inspection system an intensity(or color) image of a scene is quickly affected by optical property of objects, condition and roughness of surface, lens and filters, image sensor property and lighting system. In particular, the lighting system disign is the most important factor, since it affects overall performance of the visual system. For fast and cheap automated visual inspection system it is important to obtain the good image quality which results from careful attention to the design of the lighting system. In this paper, the lighting subsystem of AVI system is analysed for the inspection of printed circuit board(PCB) patterns. The spectral reflectance of materials, which are composed of PCB, is measured for choosing the light source. The reflection property is theoretically obtained by a reflection model and also obtained by experiments which measure intensity with varying the viewing direction of image sensor and the lighting direction of illuminator. The illumination uniformity of a ring-type illuminator. The lighting system is designed based upon the experimental results and theoretial analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.2
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• pp.131-140
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• 2016

Recent destructions of outdoor signboards have frequently been caused by strong wind, resulting in damage on the property and human livelihood. One of the major causes of the problems is inadequate implementation of structural design code to the outdoor signboards which are vulnerable to wind. This leads to this paper to present the design guideline of wind-resistant outdoor signboards. In order to estimate the design wind speed, basic wind speeds over Korea suggested by KBC(2015)(revision) are corrected with land surface roughness and topography of the terrain and installation height of the signboard. This paper also suggested the procedure of wind load estimation for different types of outdoor signboards; wall attached type, wall ribbed type and ground erected type. Since the process involves complex calculation to some extent, this paper presents summarized version of wind load estimation from non-professional point of view.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.4
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• pp.53-59
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• 2009

The purpose of this research is particle shape evaluation of granular soil and aggregate using Digital Image Process(DIP). DIP is very useful to measure the roughness and particle shape of aggregates. Couple of aggregates, like standard sand, two different crushed stones, and two different marine aggregates, have been employed. Shape factor of two different marine aggregates is ranged 0.35 to 0.54. Crushed stone I is that of 0.74 which is highly flat, but standard sand is elongated shape. Especially, two marine aggregate showed a big difference of width and length which meaned a long shape. There is any significant difference of elongation ratio and flakiness for each aggregate with different measuring system, like direct measurement of vernier calipers and DIP method. Within the limited test results, DIP is one of useful to get the particle shape of aggregate with limitation of measuring errors and to apply the particle distribution curve.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.27-33
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• 2016

This study was carried out in order to investigate the effect of binder properties in pre-coating layer on the characteristics of top-coating layer and print mottle of coated paper. Four different latices were used as a binder in pre-coating layer, and coating color prepared with a same formulation was applied for top-coating. The properties and print mottle of coated paper were evaluated. It was found that glass transition temperature (Tg) was the important factor to control the properties of pre- and top-coating layer. PPS roughness of coated paper was decreased and paper gloss was increased with applying binder which has lower Tg. Properties of top-coating layer were affected by the binder used in pre-coating layer. Print mottle of coated paper was improved with using binder which has lower Tg in pre-coating layer. These results indicate that final printability and properties of top-coating layer can be improved with using suitable binder in pre-coating layer.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.570-574
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• 2010

A diamond-like carbon (DLC) film deposited on a WC disk was investigated to improve disk wear resistance for injection molding of zirconia optical ferrule. The deposition of DLC films was performed using the filtered vacuum arc ion plating (FV-AIP) system with a graphite target. The coating processing was controlled with different deposition times and the other conditions for coating, such as input power, working pressure, substrate temperature, gas flow, and bias voltage, were fixed. The coating layers of DLC were characterized using FE-SEM, AFM, and Raman spectrometry; the mechanical properties were investigated with a scratch tester and a nano-indenter. The friction coefficient of the DLC coated on the WC was obtained using a pin-on-disk, according to the ASTM G163-99. The thickness of DLC films coated for 20 min. and 60 min. was about 750 nm and 300 nm, respectively. The surface roughness of DLC films coated for 60 min. was 5.9 nm. The Raman spectrum revealed that the G peak of DLC film was composed of $sp^3$ amorphous carbon bonds. The critical load (Lc) of DLC film obtained with the scratch tester was 14.6 N. The hardness and elastic modulus of DLC measured with the nano-indenter were 36.9 GPa and 585.5 GPa, respectively. The friction coefficient of DLC coated on WC decreased from 0.2 to 0.01. The wear property of DLC coated on WC was enhanced by a factor of 20.

• Tribology and Lubricants
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• v.34 no.4
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• pp.146-159
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• 2018

This paper presents a wear analysis procedure for calculating the wear of journal bearings of a four-strokes and four-cylinder engine operating at a constant angular crank shaft speed during firing conditions. To decide whether the lubrication state of a journal bearing is in the possible region of wear scar, we utilize the concept of the centerline average surface roughness to define the most oil film thickness scarring wear (MOFTSW) on two rough surfaces. The wear volume is calculated from the wear depth and wear angle, determined by the magnitude of each film thickness on a set of oil films with thicknesses lower than the MOFTSW at every crank angle. To calculate the wear volume at one contact, the wear range ratio during one cycle is used. The total wear volume is then determined by accumulating the wear volume at every contact. The fractional film defect coefficient, asperity load sharing factor, and modified specific wear rate for the application of the mixed-elasto-hydrodynamic lubrication regime are used. The results of this study show that wear occurs only at the connecting-rod big-end bearing. Thus, simulation results of only the big-end bearing are illustrated and analyzed. It is shown that the wear volume of each wear scar group occurs consecutively as the crank angle changes, resulting in the total accumulated wear volume.

• Science of Emotion and Sensibility
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• v.16 no.2
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• pp.157-166
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• 2013

There are few that evaluate tactile emotion as it pertains to car interior parts, while studies on visual evaluations of car interiors as well as usability tests in a visual sense are numerous. The purpose of this study is to determine typical in-vehicle tactile emotions so that they can be used to evaluate tactile impressions of car interior parts. 52 words related to tactile impressions of car interiors were gathered from a survey in conjunction with an in-vehicle test, interviews with the car salespersons, and an analysis of car reviews. After a factor analysis with 52 words, 10 categories of major tactile emotions were clustered. These were roughness, toughness, friction, comfortability, stiffness, softness, temperature, sleekness, familiarity, and flexibility. These representative tactile emotions regarding a car interior can be used to evaluate tactile impressions of surfaces such as leather, plastic, metal and wood when used as parts in car interiors.

• Korean Journal of Materials Research
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• v.18 no.7
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• pp.373-378
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• 2008

$Ba(Ti,Sn)O_3$ thin films, for use as dielectrics for MLCCs, were grown from Sn doped BaTiO3 sources by e-beam evaporation. The crystalline phase, microstructure, dielectric and electrical properties of films were investigated as a function of the (Ti＋Sn)/Ba ratio. When $BaTiO_3$ sources doped with $20{\sim}50\;mol%$ of Sn were evaporated, $BaSnO_3$films were grown due to the higher vapor pressure of Ba and Sn than of Ti. However, it was possible to grow the $Ba(Ti,Sn)O_3$ thin films with {\leq}\;15\;mol%$ of Sn by co-evaporation of BTS and Ti metal sources. The (Ti＋Sn)/Ba and Sn/Ti ratio affected the microstructure and surface roughness of films and the dielectric constant increased with increasing Sn content. The dielectric constant and dissipation factor of $Ba(Ti,Sn)O_3$ thin films with {\leq}\;15\;mol%$ of Sn showed the range of 120 to 160 and $2.5{\sim}5.5%$ at 1 KHz, respectively. The leakage current density of films was order of the $10^{-9}{\sim}10^{-8}A/cm^2$ at 300 KV/cm. The research results showed that it was feasible to grow the $Ba(Ti,Sn)O_3$ thin films as dielectrics for MLCCs by an e-beam evaporation technique.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.11
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• pp.927-933
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• 2012

The characteristics of two-dimensional supersonic coanda flow was experimentally investigated. For various ratios of slot height to coanda wall's radius of curvature, surface roughnesses, and jet stagnation pressures, the characteristics of the supersonic coanda flow such as shock structures and hysteresis were observed by flow visualization. It was found that the characteristics of hysteresis of the coanda jet was related to the surface roughness of the coanda wall. The study was further extended for application of the tangentially injected coanda jet to control co-flowing highly compressible main jet direction. It was noticed that the stagnation pressure of the main jet as well as the ratio of the slot height to coanda wall's radius of curvature wall was an influencing factor in the performance of the fluidic thrust vectoring method.