• 한국의류산업학회지
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• 제5권5호
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• pp.520-528
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• 2003

Chitosan was depolymerized by oxidizing agent, hydrogen peroxide ($H_2O_2$) and general properties of resulting low molecular weight chitosan(LMWC) were studied. Effect of amount of $H_2O_2$, ratio of $H_2O_2$/chitosan, and reaction temperature were investigated in preparing LMWC. In addition, the reduction of molecular weight of prepared LMWC were measured after a certain time passage. Pre-swelling treatment of starting chitosan affected uniform and mild reaction of depolymerization and increased the solubility of resulting LMWC. Prepared LMWC (Mw 100,000) showed a decrease in Mw by 25-35%. Prepared LMWC(Mw 60,000-70,000) showed a decrease in Mw by 10-15% after 7 months. Therefore, this depolymerizing process can be concluded desirable in terms of stability. In addition, yellowing of pre-swelling treated chitosan upon time passage was insignificant compared with that of untreated chitosan. Therefore, pre-swelling treatment of chitosan before depolymerization would be beneficial in terms of stability of physical state.

• 한국표면공학회지
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• 제40권6호
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• pp.250-253
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• 2007

Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of SKD 11 steel. Plasma nitrocarburizing was conducted for 12 h at $520^{\circ}C$ in the nitrogen, hydrogen and methane atmosphere to produce the $\varepsilon-Fe_{2-3}(N,C)$ phase. It was found that the compound layer produced by plasma nitrocarburising was predominantly composed of $\varepsilon-phase$, with a small proportion of $\gamma'-Fe_4(N,C)$ phase. The thickness of the compound layer was about $5{\mu}m$ and the diffusion layer was about $150{\mu}m$ in thickness, respectively. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of $500^{\circ}C$ for 1 hour. The very thin magnetite($Fe_3O_4$) layer $1-2{\mu}m$ in thickness on top of the compound layer was obtained by plasma post oxidation. It was confirmed that the corrosion characteristics of the nitrocarburized compound layer could be further improved by the application of the superficial magnetite layer.

• 한국환경과학회지
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• 제7권2호
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• pp.203-208
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• 1998

A simple on-line measurement system consisting of a conventional peristaltic pump, a HPLC-type heater, and a flow-through spectrophotometer is introduced for the determination of chemical oxygen demand(CODI. The system was configured such that the reaction mixture in the highly concentrated surffuric acrid medium flowing through the PTFE reaction tubing was heated at 150℃ and the absorbance of dichromate was continuously moutored at 445 m. The same addation principle as in the standard procedure was employed akcept the use of CoSO4 as a new effective catalyst. To test the system, potassium hydrogen phthalate was selected as a COD standard material. With suitably optimized reaction condition, the applicable concentration range depends on the concentration of potassium dichromate in the oxidizing reagent. With 2.0×10-3 M and 5.0×10-4M dichromate, the linear dynamic range was observed up to 400 ppm and 100 ppm, respectively. The standards in the Unear ranges were shown to be completely oxidized, which was confirmed with sodium oxalate or Mohr's salt. In all cases, the typical reproduclbility for betweenruns was 2% or less. The proposed measurement system provides the valuable in- formation for the further development of automated analysis system based on the present standard procedure.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.70-70
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• 2013

As the costs of carbon-footprinetd fuels grow continuously and simultaneously atmospheric carbon dioxide concentration increases, solar fuels are receiving growing attention as alternative clean energy carriers. These fuels include molecular hydrogen and hydrogen peroxide produced from water, and hydrocarbons converted from carbon dioxide. For high efficiency solar fuel production, not only light absorbers (oxide semiconductors, Si, inorganic complexes, etc) should absorb most sunlight, but also charge separation and interfacial charge transfers need to occur efficiently. With this in mind, this talk will introduce the fundamentals of solar fuel production and artificial photosynthesis, and then discuss in detail on photoelectrochemical (PEC) water splitting and CO2 conversion. This talk largely divides into two section: PEC water oxidation and PEC CO2 reduction. The former is very important for proton-coupled electron transfer to CO2. For this oxidation, a variety of oxide semiconductors have been tested including TiO2, ZnO, WO3, BiVO4, and Fe2O3. Although they are essentially capable of oxidizing water into molecular oxygen, the efficiency is very low primarily because of high overpotentials and slow kinetics. This challenge has been overcome by coupling with oxygen evolving catalysts (OECs) and/or doping donor elements. In the latter, surface-modified p-Si electrodes are fabricated to absorb visible light and catalyze the CO2 reduction. For modification, metal nanoparticles are electrodeposited on the p-Si and their PEC performance is compared.

• 한국표면공학회지
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• 제51권4호
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• pp.237-242
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• 2018

We report on the fabrication and photoelectrochemical (PEC) properties of a ZnO nanorod array structure as an efficient photoelectrode for hydrogen production from sunlight-driven water splitting. Vertically aligned ZnO nanorods were grown on an indium-tin-oxide-coated glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which was formed by thermally oxidizing a sputtered Zn metal thin film. The structural and morphological properties of the synthesized ZnO nanorods were examined using X-ray diffraction and scanning electron microscopy, as well as Raman scattering. The PEC properties of the fabricated ZnO nanorod photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the vertically aligned ZnO nanorod photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., $0.65mA/cm^2$ at 0.8 V vs Ag/AgCl in a 1 mM $Na_2SO_4$ electrolyte. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs Ag/AgCl, which made the device self-powered.

• 농업생명과학연구
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• 제44권1호
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• pp.9-15
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• 2010

단자엽 식물인 보리는 Agrobacterium을 이용한 형질전환이 비교적 까다로운 편이다. 본 연구에서는 큰알1호, 내쌀보리, 올보리, 새찰쌀보리, 서둔찰보리, 풍산찰쌀보리의 유묘에 알칼리, 산화제, 환원제 등을 처리하여 화학적 상처를 유발하였으며 이들에 감압진공을 이용한 Agrobacterium 형질전환을 실시한 후 GUS 유전자발현을 분석하였다. 그 결과, 보리묘 생육을 일부 저하시킬 수 있는 농도의 화학물질 처리는 각기 다른 보리 품종의 형질전환율을 전반적으로 증대시킬 수 있는 것으로 판단되었다. 화학물 중에서는 특히 hydrogen peroxide 처리가 비교적 우수한 것으로 나타났다.

• 분석과학
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• 제31권1호
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• pp.47-56
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• 2018

사건 현장에 남겨진 혈흔을 찾는 것은 사건을 재구성하거나 해결하기 위해서 매우 중요하다. 사건현장에서 사용할 수 있는 수많은 시약들이 개발되었지만, 루미놀이 가장 대표적인 시약이라고 할 수 있다. 최근에는 블루스타라는 시약이 주로 사용되고 있지만, 가격이 비싸고 시약을 제조한 후 보관이 불가능하다는 단점이 있다. 본 연구에서는 블루스타 수준의 발광강도를 유지하면서 제조 후 장시간 보관할 수 있는 새로운 루미놀 시약을 개발하고자 했다. 루미놀은 알칼리 수용액에서 잘 녹기 때문에, 시약을 제조할 때 수산화나트륨의 사용은 과산화수소의 분해를 촉진시킬 수 있다. 루미놀 시약을 제조할 때 과산화수소 안정화제로 황산마그네슘, 규산나트륨, 삼인산칼륨을 농도별로 첨가한 후, 혈흔과 반응할 때 시약의 발광강도 및 보관기간에 미치는 영향을 확인했다. 과산화수소 안정화제 첨가는 발광강도에 별다른 영향을 주지 않았고, 보관 중 루미놀 시약의 pH를 일정하게 유지시켜 줌으로서 시약의 보관기간을 크게 늘려줬다. 과산화수소 안정화제로 황산마그네슘이 가장 적절하였다. 과산화수소 대신 과붕산나트륨을 산화제로 사용했을 경우, 희석 혈흔에 대한 민감도와 발광강도에 큰 변화는 없었지만 제조 후 보관기간이 단축되었다. 그렇지만, 혈흔과 반응한 후 혼합액의 pH 상승 폭이 과산화수소로 제조한 시약보다 줄어들었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.459-462
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• 2000

The pretreatment of used newspaper for the enzymatic digestion preprocess was performed on a percolation reactor and a batch reactor. The test condition of percolation process was $170^{circ}C$, 60min, 1 mL/min, and 400psi, that of batch was $40^{circ}C$, 3hr. and latm Reaction solutions used in pretreatment process were aqueous ammonia, sulfuric acid, water, and hydrogen-peroxide as an oxidizing agent. As a result, the effect of pretreatment was similar to batch and percolation process, but the yield of enzymatic hydrolysis was higher in batch than percolation. This batch pretreatment enhanced enzymatic hydrolysis rate and increased glucose yield from about 15 to 20%. The inhibition factors influenced the rate of enzymatic hydrolysis was investigated, and the ink contented newspaper was the major factor.

• 한국환경과학회지
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• 제4권2호
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• pp.215-222
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• 1995

Thiokncillus neapolitanus R-10 isolated from sludge of night soil, showed an oxidizing activity on several malodorous sulfur compounds. The microbe successfully utilized hydrogen sulfide(H2S), methy mercaptan(MM), dimethyl sulfide(DMS) and dimethyldisulfide(DMDS) during the batch culture reaction, of which H2S was rather rapidly oxidized. To examine the ability for removal of malodorous sulfur compounds, various concentrations of sulfide substrates were supplemented separately to basal medium and their responses were investigated. As the concentration of sulfide was increased, growth was accelerated within three days of cultivation. 2.5mM was the most favorable substrate concentration of sulfide added for all cases tested. However, when the concentration of sulfur compounds were raised over 4M, they behaved as a growth inhibitor.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.680-683
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• 2000

고온성 박테리아인 Hydrogenobacter thermophilus가 생산하는 cytochrome c-552 유전자에 대한 primer를 제작하여 PCR을 통해 증폭한 후 E. coli에 cloning하였다. 또한 point mutagenesis를 통해 fusion protein을 만들기 위한 기초자료를 마련하였다. 앞으로 cytochrome c-552가 E. coli에서 mutant type으로 발현되기 위한 발현벡터의 개발과 이를 정제하는 기술을 개발하는 것이 필요할 것이다.