• Polymer(Korea)
• /
• v.34 no.5
• /
• pp.405-409
• /
• 2010

New sol-gel precursors having the ability to protect iron against corrosion were synthesized and used to prepare organic-inorganic hybrid coatings based on epoxy. Bisphenol A epoxy was modified with 3-isocyanatopropyltriethoxysilane to improve the compatibility, and water and HCl were used as catalysts for sol-gel process. Various coating formulations were prepared depending on the type of sol-gel precursors and the amount of each ingredient, and cast on iron substrates by dip-coating and thermally cured. Corrosion protection properties of coated iron were studied by a salt spray test and electrochemical impedance spectroscopy under 0.1 M NaCl electrolyte. Hybrid coatings containing anticorrosive functional group exhibited excellent corrosion protection on iron, compared to that of typical hybrid coatings. From electrochemical impedance spectroscopy, the hybrid coatings containing anticorrosive functional group could maintaine the initial impedance after 500 h, while the impedance of hybrid coatings without them started to decrease after 24 h.

• Journal of ILASS-Korea
• /
• v.12 no.1
• /
• pp.38-44
• /
• 2007

Since the Liquid Phase LPG injection (LPLI) system has Advantages in power generation and emission characteristics compared to the mixer-type fuel-supply system, a variety of studies regarding LPLi system has been conducted and its applications are made in automobile industry. However, the heat extraction due to the evaporation of liquid fuel, causes not only a post-accumulation of fuel but also an icing phenomenon which is a frost of moisture in the air around the nozzle tip. Since there exists a difficulty in the accurate control of air fuel ratio in both fuel supply systems, it can result in poor engine performance and a large amount of harmful emissions. This research examines the characteristics of icing phenomenon and develops anti-icing bushing to prevent an icing on the surface of the injection tip. It was found that n-butane, which has a relatively high boiling point ($-0.5^{\circ}C$), was a main species of post-accumulation. Also the results show that the post-accumulation problem was allevaited the utilization of a large inner to outer bore ratio and smooth surface roughness. In addition, an icing phenomenon and its formation process were found to be mainly affected by the humidity and the temperature of inlet air in an inlet duct. Also, it was observed that an icing phenomenon is lessened using aluminum bushing whose end coincides with the end of fuel injection tip in length.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.112-112
• /
• 2008

박막형 태양전지에 관한 연구는 1954년 D.C. Reynolds 가 단결정 CdS 에서 광기전력을 발견하면서부터 시작되었다. 고효율 단결정 규소 태양전지가 간편하게 제작되고 박막형 태양전지의 수명문제가 대두되어 한때는 연구가 중단되어지기도 하였으나, 에너지 문제가 심각해지면서 값이 저렴하고 넓은 면적에 쉽게 실용화 할 수 있는 박막형 태양전지에 많은 관심을 가지게 되었다. 박막형 태양전지에 사용되는 CdS는 II-VI 족 화합물 반도체로서 에너지금지대폭이 2.42eV인 직접천이형 n-type 반도체로서 대부분의 태양광을 통과시킬 수 있으며 가시광선을 잘 투과시키고 낮은 비저항으로서 광흡수층인 CdTe/$CuInSe_2$ 등과 같이 태양전지의 광투과층(윈도레이어)으로 널리 사용되고 있다. 이러한 이종접합 박막형 태양전지의 효율을 높이기 위해선 윈도레이어 재료인 CdS 박막의 낮은 전기 비저항치와 높은 광 투과도 값이 요구되어지고 있다. CdS 박막의 제작방법으로는 spray pyrolysis법, 스크린프린팅, 소결법, puttering법, 전착법, CBD(chemical bath deposition)법 및 진공증착법 등의 여러 가지 방법들이 보고되었다. 이 중 sputtering의 경우, 다른 방법들에서는 얻기 어려운 매우 얇은 두께의 박막 증착이 가능하며, 균일성 또한 우수하다. 또한 대면적화가 용이하여 양산화 기술로는 다른 제조 방법들에 비해 많은 장점을 가지고 있다. 따라서 본 연구에서는 sputtering에 의해 증착한 CdS의 박막에 광투과도 등의 향상을 위하여 CMP( chemical mechanical polishing) 공정을 적용하여 표면 특성을 개선하고자 하였다. 그 기초적인 자료로서 CdS 박막의 CMP 공정 조건에 따른 연마율과 비균일도, 표면 특성 등을 ellipsometer, AFM(atomic force microscopy) 및 SEM(scanning electron microscope) 등을 활용 하여 분석하였다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.5
• /
• pp.791-799
• /
• 1997

The wear characteristics and wear mechanisms of plasma sprayed Al/sub 2/ O/sub 3/-40%TiO/sub 2/ and Cr/sub 2/O/sub 3/ deposited on casting aluminum alloy(AC4C) were investigated. Specimens were processed for various coating thicknesses. Ball on disk type wear tester was used for wear test. The scratch test on plasma sprayed coating surface showed that critical load to break the coating layer was greater than 40 N. The critical load increase with the increase of coating thickness of specimens. The friction coefficient of Cr/sub 2/O/sub 3/ coating layer was less than that of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer. The wear resistance of Cr/sub 2/O/sub 3/ coating layer was greater than that of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer. Microscopic observation of worn surfaces was made by SEM. SEM observation showed that the main mechanism of wear for Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer was abrasive wear under 50 N. For the case of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer, as the surface cracks perpendicular to sliding direction propagated, the wear debris was generated in wear track. However, the main mechanism of wear for Cr/sub 2/O/sub 3/ coating layer was brittle fracture under 150 N.

• Research in Plant Disease
• /
• v.7 no.1
• /
• pp.37-41
• /
• 2001

This experiment was carried out to investigate the prevention of bacterial shot hole by Bordeaux mixture when it was sprayed on peach trees after harvest. bordeaux mixture was sprayed on \`Mibaeko\` peach trees 1 to 3 times after mid September, and the occurrence of bacterial shot hole was examined in the next year. Bacterial shot hole in leaves appeared from mid May and thereafter increased gradually. The more times was sprayed Bordeaux mixture, the less peaches were diseased with bacterial shot hole. At the beginning of August, the peach harvest time, the disease incidence of the untreated control plot was 27.4 to 38.1%, while the disease incidence was 9.7 to 31.8% when Bordeaux mixture was sprayed. The control value ranged from 16.5 to 64.6%. Occurrence of the fruit disease was similar to that of the leaf disease. Incidence of the fruit disease in the untreated control was 17.2 to 21.6%, but incase of the chemical treatment, it was 5.0 to 12.2 %, showing 41.9 to 70.9% of the control value. Chemical injury on peach leaves were not found in the 4-12 and 408 types, but occurred in some degrees in the 6-6 type of Bordeaux mixture.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.159-159
• /
• 2011

Among the semiconductor ternary compounds in the I-III-$VI_2$ series, $CulnS_2$ ($CulnSe_2$) are one of the promising materials for photovoltaic applications because of the suitability of their electrical and optical properties. The $CuInS_2$ thin film is one of I-III-$VI_2$ type semiconductors, which crystallizes in the chalcopyrite structure. Its direct band gap of 1.5 eV, high absorption coefficient and environmental viewpoint that $CuInS_2$ does not contain any toxic constituents make it suitable for terrestrial photovoltaic applications. A variety of techniques have been applied to deposit $CuInS_2$ thin films, such as single/double source evaporation, coevaporation, rf sputtering, chemical vapor deposition and chemical spray pyrolysis. This is the first report that $CuInS_2$ thin films have been prepared by Aerosol Jet Deposition (AJD) technique which is a novel and attractive method because thin films with high deposition rate can be grown at very low cost. In this study, $CuInS_2$ thin films have been prepared by Aerosol Jet Deposition (AJD) method which employs a nozzle expansion. The mixed fluid is expanded through the nozzle into the chamber evacuated in a lower pressure to deposit $CuInS_2$ films on Mo coated glass substrate. In this AJD system, the characteristics of $CuInS_2$ films are dependent on various deposition parameters, such as compositional ratio of precursor solution, flow rate of carrier gas, stagnation pressure, substrate temperature, nozzle shape, nozzle size and chamber pressure, etc. In this report, $CuInS_2$ thin films are deposited using the deposition parameters such as the compositional ratio of the precursor solution and the substrate temperature. The deposited $CuInS_2$ thin films will be analyzed in terms of deposition rate, crystal structure, and optical properties.

• Journal of Animal Environmental Science
• /
• v.19 no.1
• /
• pp.33-38
• /
• 2013

We conducted investigations of the information and welfare of broiler chickens in Korea. The livestock housing of all broiler chicken farms were windowless type, bell feeder and nipple waterer were used, and stocking density was relatively higher (ranging from 18.2 $birds/m^2$ to 24.2 $birds/m^2$) than RSPCA's welfare standards for chicken hens (less than 19 $birds/m^2$). The ratios of sandwich panel, urethane form, slate, and steel plate in roofing materials were 61%, 21%, 13%, and 5%, respectively. The ratios of sandwich panel, urethane form, brick, and steel plate in wall materials were 61%, 21%, 13%, and 5%, respectively. The ratios of soil and concrete in flooring materials were 10% and 90%. The mist spray, fan, and cooling pad in cooling facilities were 42%, 32%, and 26%, respectively. Thus we believe that present data contribute to develop the animal welfare certification for broiler chickens and to improve animal welfare in Korea.

• Journal of the Korean Ceramic Society
• /
• v.30 no.4
• /
• pp.325-331
• /
• 1993

Aqueous solutions of metallic salts, ZrO(NO3)2.2H2O and Y(NO3)3.5H2O were used as raw materials to synthesize crystalline submicron spherical powders of Zr0.94Y0.06O1.97 with tetragonal crystal phase. Each aqueous solution was mixed on the magnetic stirrer to homogenize for 12 hours. The concentration of the mixed solutionwas changed from 0.01mol/$\ell$ to 0.1mol/$\ell$ calculated as the concentration of Zr0.94Y0.06O1.97. Ultrafine droplets of starting mixed solution were sprayed by the ultrasonic vibrator and carried into the furnace kept at 55$0^{\circ}C$, $650^{\circ}C$, 75$0^{\circ}C$ and 85$0^{\circ}C$ using carrier gas of air (10$\ell$/min) and pyrolysed to form Y-TZP fine powders. The results of this exeriment were as follows. 1) Synthesized powders were nonagglomerated and spherical type. 2) Particle size distribution was narrow between 0.1${\mu}{\textrm}{m}$ and 1${\mu}{\textrm}{m}$. 3) Forming reaction Y-TZP was finished above synthetic temperature 75$0^{\circ}C$. 4) As the synthetic temperature rised from 55$0^{\circ}C$ to 85$0^{\circ}C$, the mean particle size decreased from 0.35${\mu}{\textrm}{m}$ to 0.22${\mu}{\textrm}{m}$ in the concentration of starting solution with 0.02mol/$\ell$. 5) At 75$0^{\circ}C$ of synthetic temperature, the concentration changes of starting solution from 0.01mol/$\ell$ to 0.1mol/$\ell$ increased the mean particle size from 0.24${\mu}{\textrm}{m}$ to 0.38${\mu}{\textrm}{m}$. 6) Chemical compositions of each synthesized particle were homogeneous nearly.

• Journal of ILASS-Korea
• /
• v.8 no.2
• /
• pp.1-6
• /
• 2003

The liquid phase LPG injection (LPLI) system (the third generation technology) has been considered as one of the next generation fuel supply systems for LPG vehicles, since it has a very strong potential to accomplish the higher power, higher efficiency, and lower emission characteristics than the mixer type(the second generation technology) fuel supply system However. when a liquid LPG fuel is injected into the inlet duct of an engine, a large quantity of heat is extracted due to evaporation of fuel. This leads to freezing of the moisture in the air around the outlet of a nozzle, which is called icing phenomenon. It may cause damage to the outlet nozzle of an injector or inlet valve seat. In this work, the experimental investigation of the icing phenomenon was carried out The results showed that the icing phenomenon and process were mainly affected by humidity of inlet air instead of air temperature in the inlet duel. Also, it was observed that the total ice formed around the nozzle weighs at about $150mg{\sim}260mg$ after injection for ten minutes. And some fuel species were found in the ice attached at the front side of a nozzle, while frozen ice attached at the back of a nozzle was mostly' consisted of moisture of inlet air. Therefore, some frozen ice deposit. detached from front nozzle of an injector, may cause a problem of unfavorable air fuel ratio control in the small LPLI engine.

• Journal of ILASS-Korea
• /
• v.14 no.4
• /
• pp.147-152
• /
• 2009

Since a liquid-phase LPG injection system allows accurate control of fuel injection and increase in volumetric efficiency, it has advantages in achieving higher engine power and lower emissions compared to the mixer type LPG supplying system. However, this system also leads to an unexpected event called icing phenomenon which occurs when moisture in the air near the injector freezes and becomes frost around the nozzle hole due to extraction of heat from surrounding caused by instant fuel vaporization. As a result, it becomes difficult to control air/fuel ratio in engine operation, inducing exacerbation of engine performance and HC emission. One effort to mitigate icing phenomenon is to attach anti-icing injection tip in the end of nozzle. Therefore, in this study, the effect of engine operation parameters as well as surrounding conditions on icing phenomenon was investigated in a bench test rig with commercially-used anti-icing injection tips. The test results show that considerable ice was deposited on the surface near the nozzle hole of the anti-icing tip in low rpm and low load operating conditions in ambient air condition. This is because acceleration of detachment of deposited ice from the tip surface was induced in high load, high rpm conditions, resulting in decrease in frost accumulation. The results of the bench testing also demonstrate that little or no ice was formed at surrounding temperature below a freezing point since the absolute amount of moisture contained in the intake air is too small in such a low temperature.