• 한국광학회지
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• 제30권1호
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• pp.1-7
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• 2019

휴대용 대공유도 미사일(Man-Portable Air Defense System)은 플룸의 중적외선 신호를 추적하는 적 항공기의 대응무기체계이다. 안개 조건에서 입자들에 의한 다중 산란현상은 중적외선 파장에서의 투과율과 휴대용 대공유도 미사일 탐지성능에 영향을 준다. 그러므로 본 연구에서 다양한 안개조건과 플룸의 특성에 따른 휴대용 대공유도 미사일의 lock-on range를 분석한다. 안개 조건에서의 광학적 소멸특성과 투과율을 분석하기 위해 미산란(Mie scattering) 이론과 복사전달방정식의 분석적 해를 활용하였다. 뿐만 아니라 중적외선 대체광원으로서 섬광탄 화염 신호를 운용했다. 다양한 시정 및 화염 온도조건에서 분석된 lock-on range는 mist 조건에서 크게 감소하며, 화염 온도가 높아질수록 증가하는 것으로 확인하였다.

• 한국표면공학회지
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• 제39권6호
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• pp.295-301
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• 2006

Hard chrome plating has been used in surface hard coating over 50 years both for applying hard coating and re-building of worn components. Hard chrome plating solution and mist pollute environment with very toxic $Cr^{6+}$(hex-Cr) known as carcinogen which causes lung cancer, High velocity oxy-fuel (HVOF) thermal spray coatings of WC base cermet and Co-alloy powders are the most promising candidates for the replacement of the traditional hard chrome plating. Surface properties, wear, and friction behaviors of micron size Co-alloy (T800) and micron size WC-l2Co (WC-Co) have been studied for the application as hard coatings. The temperature dependence of wear and friction behaviors of T800 and WC-Co have been investigated at the temperature of $25^{\circ}C$ and $538^{\circ}C$ for the application to high speed spindle.

• 한국환경과학회지
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• 제29권6호
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• pp.683-689
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• 2020

According to a NASA Goddard Institute for Space Studies report, temperatures have risen by approximately 1℃ so far, based on temperatures recorded in 1880. The 2003 heatwave in Europe affected approximately 35,000 people across Europe. In this study, a cooling fog, which is used in smart cities, was designed to efficiently reduce the temperature during a heatwave and its pilot test results were interpreted. A model experiment of the cooling fog was conducted using a chamber, in which nano mist spray instruments and spray nozzles were installed. The designed cooling fog chamber model showed a temperature reduction of up to 13.8℃ for artificial pavement and up to 8.0℃ for green surfaces. However, this model was limited by constant wind speed in the experiment. Moreover, if the cooling fog is used when the wind speed is more than 3m/s in the active green zone, the temperature reduction felt by humans is expected to be even greater. As a second study, the effect of cooling fog on temperature reduction was analyzed by installing a pilot test inside the Land Housing Institute (LHI). The data gathered in this research can be useful for the study of heat reduction techniques in urban areas.

• 한국분말재료학회지
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• 제8권3호
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• pp.151-156
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• 2001

MgO based nanocomposite powder including ferromagnetic iron particle dispersions, which can be available for the magnetic and catalytic applications, was fabricated by the spray pyrolysis process using ultra-sonic atomizer and reduction processes. Liquid source was prepared from iron (Fe)-nitrate, as a source of Fe nano-dispersion, and magnesium (Mg)-nitrate, as a source of MgO materials, with pure water solvent. After the chamber were heated to given temperatures (500~$^800{\circ}C$), the mist of liquid droplets generated by ultrasonic atomizer carried into the chamber by a carrier gas of air, and the ist was decomposed into Fe-oxide and MgO nano-powder. The obtained powders were reduced by hydrogen atmosphere at 600~$^800{\circ}C$. The reduction behavior was investigated by thermal gravity and hygrometry. After reduction, the aggregated sub-micron Fe/MgO powders were obtained, and each aggregated powder composed of nano-sized Fe/MgO materials. By the difference of the chamber temperature, the particle size of Fe and MgO was changed in a few 10 nm levels. Also, the nano-porous Fe-MgO sub-micron powders were obtained. Through this preparation process and the evaluation of phase and microstructure, it was concluded that the Fe/MgO nanocomposite powders with high surface area and the higher coercive force were successfully fabricated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.97-97
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• 2013

The exterior structures of natural organisms have continuously evolved by controlling wettability, such as the Namib Desert beetle, whose back has hydrophilic/hydrophobic contrast for water harvesting by mist condensation in dry desert environments, and some plant leaves that have hierarchical micro/nanostructures to collect or repel liquid water. In this work, we have provided a method for wettability contrast on metals by both nano-flake or needle patterns and tuning of the surface energy. Metals including steel alloys and aluminum were provided with hierarchical micro/nanostructures of metaloxides induced by fluorination and a subsequent catalytic reaction of fluorine ions on metal surfaces in water with various ranges from room to boiling temperature of water. Then, a hydrophobic material was deposited on the structured surfaces, rendering superhydrophobicity. Plasma oxidization induces the formation of superhydrophilic surfaces on selective regions surrounded by superhydrophobic surfaces. We show that wettability contrast surfaces align liquid water within patterned hydrophilic regions during the condensation process. Furthermore, this method could have a greater potential to align other liquids or living cells.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.122-122
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• 2012

The exterior structures of natural organisms have continuously evolved by controlling wettability, such as the Namib Desert beetle, whose back has hydrophilic/hydrophobic contrast for water harvesting by mist condensation in dry desert environments, and some plant leaves that have hierarchical micro/nanostructures to collect or repel liquid water. In this work, we have provided a method for wettability contrast on metals by both nano-flake or needle patterns and tuning of the surface energy. Metals including steel alloys and aluminum were provided with hierarchical micro/nanostructures of metaloxides induced by fluorination and a subsequent catalytic reaction of fluorine ions on metal surfaces in water with various ranges from room to boiling temperature of water. Then, a hydrophobic material was deposited on the structured surfaces, rendering superhydrophobicity. Plasma oxidization induces the formation of superhydrophilic surfaces on selective regions surrounded by superhydrophobic surfaces. We show that wettability contrast surfaces align liquid water within patterned hydrophilic regions during the condensation process. Furthermore, this method could have a greater potential to align other liquids or living cells.