• Journal of Biosystems Engineering
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• 제18권2호
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• pp.100-109
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• 1993

The aim of this study was to provide the reasonable data for design of the nozzle which produces finer droplets on the same level of the effective travel distance or which transports droplets to the farther target on the reasonable atomization in comparison with the commercial nozzles being used much in Korean rural areas. Newly designed twin-fluid atomizers with some commercial nozzles were tested in this study, and their results were as follows : 1. The characteristics of the spray deposit distribution of No.1 nozzles for farther target were nearly same in the near or nearer travel distance less than 8m. Therefore it was reasonable to combine the characteristics of the spray deposit distributions of No.2 and No.3 nozzles to those of No.1 nozzle. 2. The effective travel distance was increased with increase of the sectional area of the jet ligament, and the maximum effective travel distance was reached to about 17m. 3. The droplet size was increased with increase of the sectional area of the jet ligament, and the maximum droplet size was produced in the front of the point of the maximum spray deposit distribution. 4. The atomization was excellent in the twin-fluid atomizer in comparison with the hydraulic atomizer and also the effective travel distances were nearly same level in both atomizers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.1010-1013
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• 2001

Zinc oxide(ZnO) films were prepared by ultrasonic spray pyrolysis on indium (In) films deposited by evaporation and subsequently submitted to rapid thermal annealing (RTA). The RTA was processed in air or a vacuum ambient. The crystallographic properties and surface morphologies of the films were characterized before and after the RTA by X-ray diffraction (XRD) and scanning electron microscopy(SEM), respectively. The resistivity variation of the films with RTA temperature and time was measured by the 4-point probe method. Auger electron spectroscopy(AES) was carried out to figure out the distribution of indium atoms in the ZnO films. The resistivity of the ZnO on In(ZnO/In) films decreased to 2${\times}$10$\^$-3/ $\Omega$cm by diffusion of the In. The In diffusion into the ZnO films roughened the surface of the ZnO films. The results of depth profile by AES showed a hump of In atoms around ZnO/In interface after the RTA at 800$^{\circ}C$, which disappeared by the RTA at 1000$^{\circ}C$. The effects of temperature, time and ambient during the RTA on the structural and electrical properties of the ZnO/In films were discussed.

• 한국전기전자재료학회논문지
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• 제14권10호
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• pp.828-834
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• 2001

Zinc oxide (ZnO) films deposited on indium (In) films were post-annealed in a rapid thermal anealing (RTA) system. The ZnO/In films were RTA-treated in air or a vacuum ambient. The crystallographic properties and surface morphologies of the films were studied before and after the RTA by X-ray diffraction(XRD) and scanning electron microscopy (SEM), respectively. The resistivity variation of the films with RTA temperature and time was measured by the 4-point probe method. Auger electron spectroscopy (AES) was carried out to figure out the redistribution of indium atoms in the ZnO films. The resistivity of the ZnO/In films decreased to 2$\times$10$\^$-3/ Ωcm by diffusion of the In. The In diffusion into the ZnO films roughened the surface of ZnO films. The results of depth profile by AES showed a hump of In atoms around ZnO/In interface after the RTA at 800 $\^{C}$. The effects of temperature time and ambient during the RTA on the structural and electrical properties of the ZnO/In films were discussed.

• 한국재료학회지
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• 제26권9호
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• pp.472-477
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• 2016

Microstructure evolutions of thermosetting resin coating layers fabricated by electrostatic spray deposition (ESD) at various processing conditions were investigated. Two different typical polymer systems, a thermosetting phenol-formaldehyde resin and a thermoplastic polyvinylpyrrolidone (PVP), were employed for a comparative study. Precursor solutions of the phenol-formaldehyde resin and of the PVP were electro-sprayed on heated silicon substrates. Fundamental differences in the thermomechanical properties of the polymers resulted in distinct ways of microstructure evolution of the electro-sprayed polymer films. For the thermosetting polymer, phenol-formaldehyde resin, vertically aligned micro-rod structures developed when it was deposited by ESD under controlled processing conditions. Through extensive microstructure and thermal analyses, it was found that the vertically aligned micro-rod structures of phenol-formaldehyde resin were formed as a result of the rheological behavior of the thermosetting phenol-formaldehyde resin and the preferential landing phenomenon of the ESD method.

• 한국재료학회지
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• 제27권11호
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• pp.609-616
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• 2017

We investigated a Leidenfrost effect in the growth of ZnO nanostructures on silicon substrates by ultrasonic-assisted spray pyrolysis deposition(SPD). Structural and optical properties of the ZnO nanostructures grown by varying the growth parameters, such as substrate temperature, source concentration, and suction rate of the mist in the chambers, were investigated using field-emission scanning electron microscopy, X-ray diffraction, and photoluminescence spectrum analysis. Structural investigations of the ZnO nanostructures showed abnormal evolution of the morphologies with variation of the substrate temperatures. The shape of the ZnO nanostructures transformed from nanoplate, nanorod, nanopencil, and nanoprism shapes with increasing of the substrate temperature from 250 to $450^{\circ}C$; these shapes were significantly different from those seen for the conventional growth mechanisms in SPD. The observed growth behavior showed that a Leidenfrost effect dominantly affected the growth mechanism of the ZnO nanostructures.

• 태양에너지
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• 제18권2호
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• pp.137-144
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• 1998

분무열분해법으로 $SnO_2$ 박막을 증착하여 기판표면의 온도에 따른 방향성과 결함을 조사하였다. 기판의 온도가 $300^{\circ}C$일 때부터 결정성 박막이 증착되었다. 기판의 온도가 $400^{\circ}C$까지 증가함에 따라 (200)면이 우선적으로 성장하였으며 결정립의 크기도 증가하였다. Sb를 첨가하지 않은 박막은 Sn과 O로 구성되어 있으며 산소공위를 포함한다. Sb를 첨가한 박막은 산소공위 외에 Sn 위치와 O 위치에 각각 치환된 Sb와 Cl을 가진다.

• 수산해양기술연구
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• 제24권1호
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• pp.36-43
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• 1988

Boilers and diesel engines have many problems because their exhaust particles, i.e., soot have lots of bad influence on environment. And it's spray and flame have fundamentally axial symmetric shape. To investigate the relationship between fuel concentration distribution of spray and soot concentration distribution as well as temperature distribution of flame, we made a axial symmetric two phase spray-flame and analyzed the structure of is. The measuring method is the principle of the light extinction method for the spray-flame and onion peeling model is applied to analyze the radial distribution of fuel and soot concentration. The temperature of flame is measured by ø 0.4mm Pt-Pt.RH 3% thermocouple. The oils for the experiments are diesel oil and 10% water emulsified diesel oil. It was found that the soot concentration becomes higher as it comes near to the center of flame, and the fuel concentration does, too. And the soot concentration level of diesel oil is generally higher than that of the 10% water emulsified fuel. The maximum flame temperature of diesel oil is 1,17$0^{\circ}C$, however, 10% water emulsified diesel oil is 1,27$0^{\circ}C$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.293-293
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• 2012

마그네트론 스퍼터링으로 Al과 Al 합금(Al-3wt%Si, Al-10wt%Si) 박막을 코팅하였다. 기판은 냉연강판과 Si 웨이퍼를 사용하였으며 알코올과 아세톤으로 초음파 세척 후 진공용기에서 플라즈마 청정을 실서히였다. 시편 청정이 끝나면 기판은 0, 30, 45, 60, 90도의 다양한 각도로 고정시켜 Al과 Al 합금 박막을 코팅하였다. 빗각 증착 기술(Oblique Angle Deposition: OAD)은 입사증기가 기판과 수직하지 않게 기울여 코팅하는 방법으로 조직을 다양하게 제어할 수 있다. 빗각으로 코팅한 순수한 Al 박막의 경우, 동일한 두께의 박막보다 반사율 및 표면조도, 내식성이 향상되는 결과를 얻었다. 따라서 본 연구에서는 빗각 및 Si 함유량이 반사율 및 표면조도, 내식성에 미치는 영향을 비교 분석하였다. 기판의 위치에 따른 변화를 관찰하기 위해 시편은 좌, 우, 중간으로 구분하여 분석하였다. 단일층 박막의 경우 타겟과의 거리에 따른 두께 편차가 발생하였으며 이러한 두께 편차를 해결하기 위한 방법으로 동일한 각도를 유지하며 반대 방향으로 회전시켜 다층구조로 박막을 제조하였다. Si 함유량 및 빗각에 따른 반사율 및 표면조도를 분석하였으며 내식성 평가를 위한 염수 분무 테스트도 실시하여 각각의 공정 변수에 따른 결과를 비교 분석하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 추계학술대회 논문집
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• pp.352-352
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• 2015

PVD(Physical Vapor Deposition)법은 제작 조건에 따라 그 특성이 변하므로 원하는 재료 특성을 얻기 위해서는 모폴로지, 결정배향성 등에 따른 코팅막의 특성을 이해하는 것이 중요하다. 따라서 본 연구에서는 친환경 프로세스 방법인 PVD법 중 하나인 스퍼터링(Sputtering)을 이용하여 Al-Mg 막을 제작하였고, 제작된 막들에 대한 형성 메커니즘과 내식성 상관관계 해명을 위해 막의 조성분포, 표면 및 단면의 모폴로지 관찰 및 결정구조 분석을 진행하였다. 또한 염수분무 및 전기화학적 양극분극 시험을 통해 Al-Mg 막의 표면 및 단면 모폴로지가 내식특성에 미치는 영향을 고찰하였다. Al-Mg 막의 모폴로지 관찰결과 Mg 함량 및 열처리 조건에 의해 단면의 주상정 형태는 입상정 또는 무형태로 변화하였고, 표면의 모폴로지는 미세하고 치밀해지는 것으로 나타났다. 결과적으로 무형태의 단면 모폴로지와 미세하고 치밀한 표면 모폴로지를 갖는 막이 우수한 내식성을 나타내었다.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.8-15
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• 2003

During cold operation, fuel injection in the intake port directly contributes to the unburned hydrocarbon formation in spark ignition engines. The relationship between injection parameters and HC emission behavior was investigated through a series of experiments. Spray behavior of port fuel injectors was characterized through a quantitative evaluation of mass concentration of liquid fuel by a patternator and PDA(Phase-Doppler. Anemometer). A 6-hole injector was found to produce finer spray than single hole injector. Using a purpose-built wall, the wetted fuel was measured, which was mostly affected by wall temperature. HC emissions were measured in a production engine varying coolant temperature$(20~80^{\circ}C)$, also with respect to the different types of injectors. In the 6-hole injector application, the engine produced less HC emission in low coolant temperature region. Though it produces much more amount of wetting fuel, it has the advantages of finer atomization quality. In high coolant temperature region, there was little effect by different types of injectors. The control schemes to reduce HC emissions during cold start could be suggested from the findings that the amount of fuel supply and HC emission could be reduced by utilizing fine spray and high intake wall temperature.