• 한국미생물·생명공학회지
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• 제24권5호
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• pp.546-552
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• 1996

The applicability of chitosan, a biodegradable natural polymer, as the coating material to prevent the dispersal of the spores of the apple white rot agent Botryosphaeria dothidea, was investigated. The physical properties of mixed chitosan/polyvinyl alcohol(PVA) film showed the increased physical properties for film formation, such as tensil strength, elongation, and viscosity, compared to either chitosan or PVA film. The FT-IR spectra of chitosan/PVA film indicated that the film was formed by simple blending not by any new synthetic bond. The chitosan and chitosan/PVA film showed effective antifungal activity on B. dothidea. The formed films were well decomposed by ASTM strains used for biodegradability test, on the other hand, the PVA film could not be decomposed by above standard strains. The field test at apple orchard showed that the dispersal of B. dothidea spores could be effectively reduced by coated film, especially by chitosan/PVA film. The spore dispersal was reduced upto 97.0% by 1.0% chitosan/5.0% PVA film during 4 months.

• 한국세라믹학회지
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• 제54권5호
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• pp.429-437
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• 2017

Micro hollow plate type silica with low refraction properties was synthesized and its hollow structure was applied as an optical structure to develop a light diffusion material that simultaneously satisfies the requirements of good light diffusibility, high transmissibility, and high luminance. The developed light diffusion material was applied to a light diffusion film and the film's optical properties were assessed. Hollow silica was synthesized by precipitation method using $Mg(OH)_2$ core particles, sodium silicate, and ammonium sulfate as the silica precursors. The concentration of the silica precursor was adjusted to control hollow silica shell thickness. The total light transmittance of the light diffusion film composed of the hollow silica was 94.55%, which was 4.57% higher than that of the PC film; new film's haze was 71.20%, which was 70.9% higher. Furthermore, the luminance increased by 5.34% compared to that of the light source. The reason for the results is not only that the micro plate type hollow silica, which has a low refractive property, played a role in reducing the difference in refractive index between the medium boundaries, but also that there was a light-concentrating effect due to the changing of light paths to the front direction inside the hollow structure. Optical simulation verified the enhanced optical properties when hollow silica was applied to the light diffusion film.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.135-138
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• 2001

We report the structural ,optical and electrical properties of ZnO thin films depending on the variation of the film thickness. The properties of the films deposited on sapphire (001) substrates using a pulsed laser deposition technique (PLD) were characterized with XRD, hall measurement and photoluminescence (PL). In our study, the increase of the thickness of ZnO thin films shows the improvement of the structural and optical properties. The electric properties of the films were also well matched with the structural and optical properties

• Corrosion Science and Technology
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• 제5권4호
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• pp.141-148
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• 2006

The chemical composition and the semiconducting properties of the passive films formed on Alloy 690 in various film formation conditions were investigated by XPS, photocurrent measurement, and Mott-Schottky analysis. The XPS and photocurrent spectra showed that the passive films formed on Alloy 690 in pH 8.5 buffer solution at ambient temperature, in air at $400^{\circ}C$, and in PWR condition comprise $Cr_2O_3$, $Cr(OH)_3$, ${\gamma}-Fe_2O_3$, NiO, and $Ni(OH)_2$. The thermally grown oxide in air and the passive film formed at high potential (0.3 $V_{SCE}$) in pH 8.5 buffer solution were highly Cr-enriched, whereas the films formed in PWR condition and that formed at low potential (-0.3 $V_{SCE}$) in pH 8.5 buffer solution showed relatively high Ni content and low Cr content. The Mott-Schottky plots exhibited n-type semiconductivity, inferring that the semiconducting properties of the passive films formed on Alloy 690 in various film formation conditions are dominated by Cr-substituted ${\gamma}-Fe_2O_3$. The donor density, i.e., concentration of oxygen vacancy, was measured to be $1.2{\times}10^{21}{\sim}4.6{\times}10^{21}cm^{-3}$ and lowered with increase in the Cr content in the passive film.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.22-25
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• 2002

In this paper, we deposited MgO buffer layer on p-type (100)Si substrate in the condition of substrate temperature 400$^{\circ}C$, working gas ratio Ar:O$_2$=80:20, RF Power 50W, working pressure 10mtorr, and the thickness of the film was about 300${\AA}$. Then we deposited Ba$\sub$0.5/Sr$\sub$0.5/TiO$_3$ thin film using RF Magnetron sputtering method on the MgO/Si substrate in various RF power of 25W, 50W, 75W. The film deposited in 50W showed the best crystalline from the XRD measurement. To know the electrical properties of the film, we manufactured Al/BSTMgO(300${\AA}$)/Si/Al structure capacitor. In the result of I-V measurement, The leakage current density of the capacitor was lower than 10$\^$-7/A/$\textrm{cm}^2$ at the range of ${\pm}$150kV/cm. From C-V characteristics of the capacitor, can calculate the dielectric constant and it was 305. Finally we deposited BST thin film on bare Si substrate and (100)MgO substrate in the same deposition condition. From the comparate of the properties of these samples, we found the properties of BST thin film which deposited on MgO/Si substrate were better than on bare Si substrate and similar to on MgO substrate.

• 한국재료학회지
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• 제4권5호
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• pp.535-540
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• 1994

Thin film magnet was fabricated by radio frequency magnetron sputtering using $Nd_13/(Fe.Co)_{70}B_{17}$ alloy target and magnetic properties were investigated according to sputtering conditions from the metallurgical point of view. we could obtain the best preferred orientation of $Nd_2Fe_{14}B$ phase at substrate temperatures between $450^{\circ}C$ and $460^{\circ}C$ with the input power 150W, and thin films had the anisotropic magnetic properties. But, as the thickness of thin film increased, the c-axis orientation gradually tended to be disordered and magnetic properties also become isotropic. Just like Nd-Fe-B meltspun ribbon, the microstructure of thin film magnet was consisted of very find cell shaped $Nd_2Fe_{14}B$ phase and the second phase along grain boundary. While, domain structure showed maze patterns whose magnetic easy axis was was perpendicular to film plane of thin film. It was concluded from these results that the perpendicualr anisotropy in magnetization was attributed to the perpendicular alignment of very find $Nd_2Fe_{14}B$ grains in thin film.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.359-366
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• 2000

A numerical study has been performed for the 2-dimensional film cooling employed in the cooling of hot components such as gas turbines. The flow and heat transfer characteristics are numerically simulated using FLUENT software. Blowing ratios vary from 0.25 to 5.0 and coolant injection angles vary from $15^{\circ}\;to\;60^{\circ}\;in\;15^{\circ}$ increment. The result shows that, for all cases, there exists a blowing ratio which maximizes film cooling effect (measured by the distance from the slot exit to the downstream wall location at which temperature increases to 900 K) for a given injection angle. It is also observed that the film cooling effectiveness decreases when downstream wall is sunk or lifted. The simulation has been performed using both constant properties and temperature dependent variable properties. It is found that the cases with constant properties overestimate the film cooling effect considerably.

• 한국표면공학회지
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• 제24권4호
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• pp.179-186
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• 1991

The effects of silicone contents and flow rates(agitation rates) of electrolyte on the formation and mechanical properties of hard anodized film of Al-Si alloy have been studied in 12% H2SO4 + 1% Oxalic acid with varying the silicone contents in the rance of 0 to 11.6% and the flow rates of electrolyte in the range of 0 to 90cm/sec. The film forming voltage required to maintain an equivalent current density significantly increase with the silicone content of Al-Si alloys due to a low conductivity of silicone. Hardness and wear resistance of the anodized film of Al-Si alloys decreases wit increasing the silicone content. The increase in the flow rate of electrolyte has a similar influence on the formation and mechanical properties of anodized film as does the decrease in bath temperature. Hardness of anodized film is rapidly increased with the flow rate being increased from 10cm/sec. It is observed that the increase in the flow rate from 11cm/sec. It is observed that the increase in the flow from 11cm/sec to 48cm/sec is more effective in enhancing the hardness of film than is the decrease in bath temperature from 1$0^{\circ}C$ to $0^{\circ}C$.

• 한국염색가공학회지
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• 제16권5호
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• pp.28-34
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• 2004

The polarizing film application exploits the unique physicochemical properties between PVA(Poly vinyl alcohol) film and CTA(Cellulose triacetate) film. However, hardly any research was aimed at improving the adhesion characteristics of the CTA film by radio frequency(RF) plasma treatment at argon(Ar) gaseous state. In this report, we deal with surface treatment technology for protective CTA film developed specifically for high adhesion applications. After Ar plasma, surface of the films is analyzed by atomic force microscopy(AFM), roughness parameter and peel strength. Furthermore, the wetting properties of the CTA film were studied by contact angle analysis. Results obtained for CTA films treated with a glow discharge showed that this technique is sensitive to newly created physical functions. The roughness and peel strength value increased with an increase in treatment time for initial treatment, but showed decreasing trend for continuous treatment time. The result of contact angle measurement refer that the hydrophilicity of surface was increased. AFM studies indicated that no considerable change of surface morphology occurred up to 3 minutes of treatment time, but a considerable uneven of surface structure resulted from treating time after 5 minutes.

• 폴리머
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• 제36권5호
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• pp.599-605
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• 2012

기상중합으로 제조된 poly(3,4-ethylenedioxythiophene)(PEDOT) 박막을 다양한 금속 알콕사이드 졸 용액으로 후처리하여 내용제성, 내스크래치성, 연필경도와 같은 물리화학적 특성을 효과적으로 개선하였다. 기상중합으로 제조된 PEDOT 층위에 금속 알콕사이드의 졸-젤 공정으로부터 유도된 금속 산화막이 형성되어 전기적 특성의 큰 손실 없이 기계적 물성을 증대시킬 수 있었다. 금속 알콕사이드 졸은 다양한 기능기를 가지는 실리콘 및 티타늄계 알콕사이드 화합물을 사용하였다. 이 중에서 tetraethyl orthosilicate를 기반으로 한 금속 알콕사이드 졸을 사용한 경우의 PEDOT-금속산화물 복합 박막이 표면저항, 투과도 및 다양한 물리화학적 물성 관점에서 가장 우수하였다. PEDOT-금속산화물 복합 박막의 전기적, 광학적, 물리화학적 특성 관점에서의 최적화를 위하여 금속 알콕사이드 졸의 함량, 산화제 함량, 후처리 후의 건조온도에 따른 효과를 살펴보았다.