• 에너지공학
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• 제8권2호
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• pp.272-278
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• 1999

본 연구에서는 지름 30mm, 길이 45mm인 brass와 aluminium 원통 실린더의 접촉면이 ⅰ) 진공 상태에 있을 때 , ⅱ) silicone grease를 충전하였을 때 , ⅲ) silicone grease와 aluminium 분말 (#325) 혼합물을 충전하였을 때의 열접촉저항을 측정하였고, 그 결과를 Fouche 의 해석 모델과 비교하였다. 진공상태에서 비접촉면의 열접촉저항은 표면의 가공 상태에 따라 (2~100)$\times$$10^{-5}$($m^2$$^{\circ}C$/W)의 분포를 나타내었고 접촉 표면을 연마하였을 때에는 거친 표면에 비하여 약 30~50%의 열접촉저항저감을 나타내었다. 그러나, silicone grease를 충전했을 때에는 열접촉저항 값이 약 5~10정도 감소하는 경향을 나타내었다. Fouche 모델을 이용한 해석 결과는 silicone grease로 충전한 접촉면에 대해서 각 10~30%범위에서 아주 잘 일치하였다.

• 한국세라믹학회지
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• 제33권10호
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• pp.1138-1146
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• 1996

Al2TiO5 powder was prepared by the sol-gel processing from th metal alkoxides ; aluminium sec-butoxide (Al(OC4H9)3 and tetraethyl orthotitanate (Ti(OC2H5)4) The particles of Al2TiO5 produced from alkoxides were measured to be below $1.5mutextrm{m}$ and mre than 90% weere below 1 ${\mu}{\textrm}{m}$ however those from commercial alumina and titania were over 0.5-7${\mu}{\textrm}{m}$ and only 60% were below 1${\mu}{\textrm}{m}$ and 90% were below 2.5${\mu}{\textrm}{m}$ Therefore Al2TiO5 powder produced from alkoxides had the narrower distributionin size than that produced from the commercial alumina and titania powders. The addition of mullite or Al2O3 powder to the prepared aluminum titanate inhibited the grain growth and this resulted in decreased and increase in density.

• 한국정밀공학회지
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• 제23권2호
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• pp.146-153
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• 2006

Acceleration sensors have widely been used in the various fields of industry. In recent years, micromachining accelerometers have been developed and commercialized by the micromachining technique or MEMS technique. Typical structure of such sensors consist of a cantilever beam and a vibrating mass fabricated on Si wafers using etching. This study investigates the feasibility of powder blasting technique for microfabrication of sensor structures made of the pyrex glass alternating the existing Si based acceleration sensor. First, as preliminary experiment, effect of blasting pressure, mass flow rate of abrasive and no. of nozzle scanning on erosion depth of pyrex and soda lime glass is studied. Then the optimal blasting conditions are chosen for pyrex sensor. Structure dimensions of designed glass sensor are 2.9mm and 0.7mm for the cantilever beam length and width and 1.7mm for the side of square mass. Mask material is from aluminium sheet of 0.5mm in thickness. Machining results showed that tolerance errors of basic dimensions of glass sensor ranged from 3um in minimum to 20um in maximum. This results imply the powder blasting can be applied for micromachining of glass acceleration sensors alternating the exiting Si based sensors.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.729-730
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• 2006

The research involves the development of a powder metallurgical route for producing good quality TiAl targets for making physical vapour deposition (PVD) coatings. Mixtures of elemental titanium and aluminium powders were mechanically milled using a novel discus milling technique under various conditions. Hot isotropic pressing (HIP) was then employed for consolidation of the mechanically alloyed powders. A cathodic arc vapour deposition process was applied to produce a TiAlN coating. Microstructural examination was conducted on the target material and PVD coatings, using X-ray diffractometry (XRD), X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM). It has been found that combining mechanical alloying and HIP enable us to produce fairly good quality of TiAl based target. The PVD coatings obtained from the TiAl target showed very high microhardness values.

• 한국물환경학회지
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• 제27권4호
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• pp.486-490
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• 2011

As(V) adsorption on aluminum oxide powder which was recycled from industrial wastes containing aluminum hydroxide was evaluated. Aluminum oxide powder in this study was prepared by calcinating aluminum hydroxide wastes at$550^{\circ}C$. Spectroscopic analysis indicated that the aluminum hydroxide wastes were changed to aluminum oxide by calcination. Arsenic adsorption isotherm was conducted with variation of ionic strength and multiple-ion systems using Ca(II) and Cu(II). As(V) removal showed typical anionic adsorption characteristics that the removal efficiency decreased with increasing pH in single As(V) system as well as in binary and ternary system. More than 80% of As(V) at an initial concentration of $5{\times}10^{-5}$ M was removed from aluminum oxide powder in As(V) single system. The effect of ionic strength on As(V) adsorption was negligible, which indicated the strong bonding between aluminum oxide powder and As(V). The removal efficiency of As(V) was higher in a binary system with Cu(II) than in a binary system with Ca(II).

• 한국세라믹학회지
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• 제30권7호
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• pp.589-597
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• 1993

The optimum sol solution for making alumina membrane was synthesized by using sol-gel method with aluminium isopropoxide. Two types of supports were made from the $\alpha$-Al2O3 powder. The porosities of supports could be controlled by the forming methods and the heat treatment conditions. After the support was coated with optimum sol solution and heat-treated at 50$0^{\circ}C$ for 1hour, the thickness of crack-free membrane could be controlled reproductively with dipping time.

• 한국식품저장유통학회지
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• 제13권6호
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• pp.681-685
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• 2006

가루녹차를 알루미늄 포장에 보관하여 $-5^{\circ}C$에서 저장시 품질관련 화학성분인 총질소, 총아미노산, 탄닌, 카페인, 엽록소, 비타민 C 및 지방산은 저장기간이 길어질수록 함량이 감소되었다. 가루녹차의 표면색상은 $-5^{\circ}C$ 저장시 a값은 저장전 -17.40에서 저장 30일 -16.69, 저장 60일 -16.20, 저장 120일 -13.69로 저장기간이 길어질수록 녹색이 감소됨을 알 수 있었다. 외관과 내질에 따른 관능평가는 저장전 93점에서 저장 60일 88점, 저장 120일 73점으로 저장기간 경과에 비례해 품질이 열악해졌다. 품질을 고려하면 $-5^{\circ}C$에서 가루녹차를 저장하는 것이 우수한 저장방법이 되리라 생각된다.

• Applied Biological Chemistry
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• 제19권3호
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• pp.145-154
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• 1976

현재(現在) 식품공업(食品工業)에 널리 이용(利用)되고 있는 포장재료(包裝材料)를 가지고 건조(乾燥)통고추와 고추분말(紛末)을 포장(包裝)하여 여러 조건(條件)에 저장(貯藏)하면서 포장재료(包裝材料)와 시료(試料)의 물리적(物理的) 및 화학적(化學的) 변화(變化)에 관(關)하여 연구검토(硏究檢討) 한바 다음과 같은 결과(結果)를 얻었다. 고추의 저장조건중(貯藏條件中), 상대습도(相對濕度) 55% 이상(以上)에서는 수분흡수(水分吸收)가 현저(顯著)하게 상승(上昇)하였으며, 10%에서는 곰장이가 발생(發生)하였는데 이때의 평형수분(平衡水分) 함량(含量)은 15%로써 고추의 저장수분(貯藏水分) 함량(含量)의 임계점(臨界點)에 도달(到達)하였다. 시료(試料)의 수분함량(水分含量)을 달리하여 저장(貯藏)하였을 때 색소(色素) Capsanthin함량(含量)은 저장온도(貯藏溫度)가 높을수록, 수분함량(水分含量)이 많아질수록 감소(減少)하였으며, 천일하(天日下)에 방치(放置)할때도 Capsanthin함량(含量)은 크게 변화(變化)하였다. 여러 포장재료중(包裝材料中) Aluminium foil packet이 장기저장시(長期貯藏時) 고추 성분(成分)의 변화(變化)를 줄이는데 가장 효과적(效果的)이였으며 단기저장시(短期貯藏時)에는 착색(着色) Polyethylene, L.D.P.E., Saran/cello, /Saran/P.E., 순서(順序)였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.289-292
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• 2001

Aluminium foams, having a closed cell structure, fabricated by applying the powder compact method and an induction heating were studied. The powdered A6061 mixed with the powdered titanium hydride as a foaming agent was hot pressed into a foamable precursor. The resulting precursor was foamed by induction heating up to desired temperature. The effects of the titanium hydride content ($0.3{\~}1.5 wt.\%$), pressing pressure of the foamable precursor material (50-150kN), the forming temperature ($610{\~}690^{\circ}C$) and heating rate during foaming on the expansion behavior of the foam were investigated.

• 한국분말재료학회지
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• 제19권5호
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• pp.367-372
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• 2012

Single crystalline Cu nanowires with controlled diameters and aspect ratios have been synthesized using electrochemical deposition within confined nanochannels of a porous anodic aluminium oxide(AAO) template. The diameters of nano-sized cylindrical pores in AAO template were adjusted by controlling the anodization conditions. Cu nanowires with diameters of approximately 38, 99, 274 nm were synthesized by the electrodeposition using the AAO templates. The crystal structure, morphology and microstructure of the Cu nanowires were systematically investigated using XRD, FE-SEM, TEM and SAED. Investigation results revealed that the Cu nanowires had the controlled diameter, high aspect ratio and single crystalline nature.