• 대한기계학회논문집B
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• 제22권5호
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• pp.563-572
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• 1998

An experimental study of hot filament chemical vapor deposition(HFCVD) has been carried out for the fabrication of diamond thin film. Of particular interest is the measurement of deposition uniformity on large substrates. Experimental apparatus including a vacuum chamber, heating elements, etc. has been designed and manufactured. Deposition profiles for different pretreatment powders and different flow rates have been measured in conjunction with the measurement of substrate temperature distribution on a large substrate surface. As the flow rate increases, deposition rate increases, however, the crystallinity becomes worse. Higher growth rate has been found on the region closer to the center location where substrate temperature is higher. The crystallinity has been improved as gas flow rate decreases. The growth rate and morphology of deposition were identified by SEM and the existence of diamond phase was proved by Raman spectroscopy.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1133-1137
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• 2011

Ordered array of gold nanoparticles (Au NPs) over ITO glass was investigated in terms of ITO pretreatment, particle size, and diamines with different chain length. Owing to the indium-tin-oxide (ITO) layer coated on the glass, the substrate surface has a limited number of hydroxyl groups which can produce functionalized amine groups for Au binding, which resulted in the loosely-packed array of Au NPs on the ITO surface. Diamine ligand as a molecular linker was introduced to enhance the lateral binding of adjacent Au NPs immobilized on the amine-functionalized ITO glass, consequently leading to the densely-packed array of Au NPs over the ITO substrate. The molecular bridging effect was strengthened with the increase of chain length of diamines: C-12 > C-8. The packing density of small Au NPs (< 40 nm) was significantly increased with the increase of C-8 diamine, but large Au NPs (> 60 nm) did not produce densely-packed array on the ITO glass even for the dosage of C-12 diamine.

• 한국세라믹학회지
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• 제29권12호
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• pp.926-934
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• 1992

Uniform diamond films in a few $\textrm{mm}^2$ size and locally isolated diamond single crystals in size of 60 $\mu\textrm{m}$ were synthesized on Si-wafer and Al2O3 substrate by the method of acetylene flame. The effects of substrate temperature and flow ratio of oxygen to acetylene on the morphology of deposited diamond were investigated. According to the observations of growth behavior of diamond on Si substrate with respect to substrate surface pretreatment and flow ratio, it was shown that well faceted diamonds could grow uniformly when flow ratio was above 0.9 and substrates were densely scratched. With increasing substrates temperature, the crystal morphology changes from octahedron bounded by only {111} plane below 850$^{\circ}C$ to cubo-octahedron with almost equal development of {111} and {100} plane in the temperature range of 850∼950$^{\circ}C$. Between 950∼1050$^{\circ}C$, the {111} faces become rough and concave. Above 1050$^{\circ}C$, new crystallites begin to grow on concave {111} surface and overall morphology looks like cubo-octahedron with degenerated {111} faces. These changes of morphology can be understood in terms of the different growth mode of each crystallographic plane with respect to the substrate temperature and supersaturation. And the observed phenomena on {111} planes can be related to the face instability and twin generation.

• 한국재료학회지
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• 제8권2호
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• pp.131-134
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• 1998

$SiO_{2}$ 기판과 dimethylethylamine alane(DMEAA)을 반응소스로 하여 알루미늄을 증착시켜 증착전 전처리 가스 종류와 수소 플라즈마 처리에 따른 증착속도의 차이와 미세구조에 대하여 연구하였다. TiN기판에 증착된 알루미늄의 증착속도는 증착전 수소 가스에 의한 전처리한 경우 아르곤이나 헬륨에 의한 전처리에 비해 빠른 증착속도를 나타내었다. 이르곤 플라즈마 전처리나 플라즈마 전처리 하지 않고 $SiO_{2}$기판에 알루미늄을 증착하였을 경우에 비해 수소 플라즈마 전처리에 의해 알루미튬증착시 잠복기(incubation time)가 감소하였으며 치밀한 미세조직을 얻을 수 있었다.

• 한국미생물·생명공학회지
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• 제43권1호
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• pp.16-21
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• 2015

2세대 바이오매스 볏짚을 이용하여 전자선 조사 후 NMMO 처리 공정을 수행하고 이를 분석하였다. 볏짚은 전자선 500 kGy 조사 후 NMMO 처리를 한 경우 72시간의 효소당화를 거쳐 글루코스 60.8%와 자일로스 9.7% 포함 약 83.8% 정도의 당수율을 보였다. 이 전처리 공정은 유해한 화학물질을 사용하지 않아서 친환경적이며 전자선 조사와 NMMO 처리의 시너지 효과가 있음을 알 수 있었다. 그러나 전자선 조사량이 너무 높다는 단점이 있으며 추후에는 낮은 전자선 조사량과 여러 가지 단일공정을 통합한 새로운 복합전처리 방법 연구의 필요성이 있다. 따라서 이 단점을 보완한다면 전자선 조사라는 친환경적 방법과 더불어 NMMO 용액의 재활용성을 이유로 바이오에탄올 생산 등의 산업현장에의 적용 가능성이 높다는 것을 알 수 있었다.

• 펄프종이기술
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• 제47권4호
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• pp.21-29
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• 2015

In this study, the feasibility of utilizing wood chips from pitch pine (Pinus rigida) was evaluated for bioethanol production by an organosolv pretreatment and enzymatic saccharification. When wood chips from pitch wood were pretreated with 75% (v/v) ethanol and 1.7% sulfuric acid as a catalyst at H-factor 2000, average pulp yield was 43.3%, which pretreated wood fibers showed higher glucan (55.8%) and lower lignin (12.2%) contents than untreated control (43.9% glucan and 27.8% lignin). After enzymatic saccharification, the organosolv pulps with 56.2% delignification rate reached above 97% conversion rate of cellulose to glucose. These results indicated that increasing the delignification rate causes micro pores on the surface of organosolv pulps resulting in improved the accessibility of enzyme onto the substrate. Moreover, it was in agreement with the SEM examination of wood fibers.

• 한국식품영양과학회지
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• 제27권6호
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• pp.1110-1116
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• 1998

To determine the optimum conditions for the enzymic hydrolysis against wheat gluten of high con centrations (6~14%, w/w, protein), a hydrolysis system combining weak acid pretreatment and enzymic hydrolysis was investigated. Alcalase showed the highest DH(degree of hydrolysis) of the tested proteases. After hydrolysis by alcalase, subsequently peptidases were applied for the better DH of the wheat gluten hydrolyzate. Peptidase NP2 showed the highest DH of the tested peptidases, but flavour zyme was shown for the lowest bitter taste of the resulting hydrolyzate. In order to minimize aggregation or gelling at higher initial substrate concentration during heat treatment, wheat gluten suspension was pretreated with possibly low concentrations of hydrochloric acid at 105oC for 1 hour, and then enzy matically hydrolysed with alcalase and subsequently with flavourzyme. Each required minimum concen tration of hydrochloric acid in the wheat gluten suspension of 6, 8, 10, 12, and 14%(w/w, protein) was 0.10, 0.15, 0.20, 0.225, and 0.275N, respectively. After the subsequent enzymic treatment by alcalase and peptidase NP2 for 24 hrs, the nitrogen solubility in the final wheat gluten hydrolysates was increased to 94.9, 86.4, 85.3, 89.3 and 95.0%, and their amino nitrogen content was increased to 2.87, 5.68, 7.34, 9.71 and 12.50mg/m, respectively.

• KSBB Journal
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• 제28권5호
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• pp.282-286
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• 2013

The seaweed, Gelidium amansii, was fermented to produce bioethanol. Optimal pretreatment condition was determined as 94 mM $H_2SO_4$ and 8% (w/v) seaweed slurry at $121^{\circ}C$ for 60 min. The mono sugars of 40.4 g/L with 67% of conversion from total carbohydrate of 60.6 g/L with 80 g dw/L G. amansii slurry were obtained by thermal acid hydrolysis pretreatment and enzymatic saccharification. G. amansii hydrolysate was used as the substrate for ethanol production by Kluyveromyces marxianus KCTC 7150 and Candida tropicalis KCTC 7212 using 5L fermentor. The ethanol productions by K. marxianus KCTC 7150 and C. tropicalis KCTC 7212 were 17.8 g/L with $Y_{EtOH}$ of 0.48 at 120 h and 19.3 g/L with $Y_{EtOH}$ of 0.50 at 120 h, respectively.

• 전기화학회지
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• 제20권1호
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• pp.1-6
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• 2017

본 연구에서는 구리 배선 공정에서 구리 씨앗층 표면에 형성되는 구리 자연산화물을 제거하는 표면 전처리가 후속 구리 전착에 미치는 영향을 살펴보았다. 구리 배선 공정의 화학적 기계적 연마 공정에서 사용하는 citric acid 기반의 용액을 구리 표면 전처리 과정에 적용하여 표면에 존재하는 구리 자연 산화물을 제거하였고, 용액 조성 변화를 통해 산화물 제거의 선택성을 높여 구리 씨앗층의 손실을 최소화하였다. 또한 표면 전처리 후 구리 전해 전착과 무전해 전착을 시도하여 전착한 박막의 비저항, 표면 거칠기 등의 성질을 비교하고, 이를 통해 선택적으로 구리 산화물을 제거한 이후에 전착된 박막의 비저항과 표면 거칠기가 가장 낮게 나타남을 확인하였다.

• Journal of the Korean Wood Science and Technology
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• 제42권2호
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• pp.172-182
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• 2014

Extraction is a necessary element in the bioconversion of lignocellulosics to fuels and chemicals. Although various forms of chemical pretreatment of cellulosic materials have been proposed, their effectiveness varies depending on the treatment conditions and substrate. In this study, mixed hardwood (MH) and loblolly pine (LP) were pretreated with dilute acid in a 100 mL accelerated solvent extraction (ASE) at the predetermined optimal conditions: temperature: $170^{\circ}C$, acid concentration: 0.5% (w/v), and reaction time: 2~64 min. This method was highly effective for extracting the hemicellulose fraction. Total xmg (defined as the sum of xylose, mannose, and galactose) can be extracted from milled MH and LP through pressurized dilute acid treatment in maximum yields of 12.6 g/L and 15.3 g/L, respectively, representing 60.5% and 70.4% of the maximum possible yields, respectively. The crystallinity index increased upon pretreatment, reflecting the removal of the amorphous portion of biomass. The crystalline structure of the cellulose in the biomass, however, was not changed by the ASE extraction process.