• 보존과학연구
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• s.35
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• pp.111-119
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• 2014

Microorganisms were isolated from Dongchundang(wooden cultural heritage) with PDA medium culture. Nineteen species shows the cellulolytic activity. Methylobacterium sp. was the most active in cellulose degradation. The growth curve and pH were measured during incubation of the microorganism for 72 hours. The pH was increased with the increasing of microbial growth. The degree of cellulose degradation was determined with the amount of reducing sugar by use of dinitrosalicylic acid (DNS) method. The amount of reducing sugar was decreased after 45 hours. As a results, It should suggested that wood component were deteriorated by Methylobacterium sp..

• Journal of the Korean Wood Science and Technology
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• v.39 no.1
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• pp.86-94
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• 2011

Pyrolytic lignin was obtained from biooil produced with yellow poplar wood. Fast pyrolysis was performed under various temperature ranges and residence times using fluidized bed type reactor. Several analytical methods were adopted to characterize the structure of pyrolytic lignin as well as the effect of pyrolysis temperature and residence time on the modification of the lignin. The yield of pyrolytic lignin increased as increasing pyrolysis temperature and decreasing residence time of pyrolysis products. The molecular weight of pyrolytic lignin determined by gel permeation chromatography (GPC) was approximately 1,200 mol/g, which was approximately a tenth of milled wood lignin (MWL) purified from the same woody biomass. Based on analytical data, demethoxylation and side chain cleavage reaction were dominantly occurred during fast pyrolysis.

• Analytical Science and Technology
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• v.8 no.3
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• pp.335-340
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• 1995

Automatic biochemical oxygen demand(BOD) measurement system has heen developed using a microbial membrane electrode, prepared from Bacillus subtilis and polyvinyl alcohol(PVA). The automatic BOD measurement system showed a linear response curve up to BOD 60 ppm using a glucose/glutamic acid standard solution, and all the BOD measurement processes are carried out automatically to calculate BOD whithin 10 min after each sample injection. The response times of the microbial electrode was 5 minutes with a 5 min recovery time between measurements and the relative error of the BOD estimation was within 10%.

• Journal of Radiation Protection and Research
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• v.26 no.4
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• pp.425-432
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• 2001

A bacteria infection on film cassette contact surface was examined at the diagnostic radiology department. Studies have demonstrated a bactericidal effect of ultraviolet irradiation, and to assess the contamination level on film cassette contact surface as a predictor of patient prevent from nosocomial infection. The study showed that the laboratory result was identified non-pathologic and pathologic bacterial in the five different cassette size of the contact surface. Film cassettes were exposed to ultraviolet light for 1, 2 and 3 minutes. Ultraviolet light disinfection practices suitable for bacteria. The study concludes that presence of a bacterial infection will prevent a using antiseptic technique on film cassette contact surface. In conclusion, ultraviolet irradiate on film cassette over the surface more than 2 minutes. Ultraviolet dose of $1565 {\mu}W{\codt}s/cm^2$ Win in 30 second relative to ultraviolet dose in time.

• Journal of the Korean Geotechnical Society
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• v.29 no.10
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• pp.29-37
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• 2013

Organic soils are widely distributed at Youngdong areas in Kangwon prefecture and Jeonbuk area. Such organic soils usually consist of undecomposed fiber materials. It is difficult to exactly measure the water content of such organic soils because some organic materials may decompose at $110^{\circ}C$ in drying oven. In this study, both drying oven and microwave oven methods are used to measure the water content of organic soils. Three different levels of oven temperature, $60^{\circ}C$, $80^{\circ}C$, and the standard temperature of $110^{\circ}C$, were used to measure the water content of organic soils in the 1st, 2nd, and 3rd day. The water content by microwave oven was measured for two different sample masses (30, 60 g) with five different measuring times (3, 6, 9, 12, 15 min.). As the temperature increased, the water content of organic soils increased due to the decomposition of organic materials in soils. The water content of some soils increased up to 2 times as the temperature was increased from $60^{\circ}C$ to $110^{\circ}C$. However, the water content was not changed after the 1st day, regardless of drying oven temperature and soil types. The water content by microwave oven became constant after 12 min. for the 30 g sample and 15 min. for the 60 g sample used. The measured water content by microwave oven was similar to that measured by drying oven at $60^{\circ}C$.

• Journal of Sericultural and Entomological Science
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• v.45 no.1
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• pp.46-57
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• 2003

This study was carried out to investigate the characteristics of the soluble sericins after degumming and after hydrolysis of insoluble sericin with various enzymes. Especially, the hydrolysis characteristics were examined in terms of molecular weight of the soluble sericin. Amino acid composition and molecular weight characteristics of the soluble sericins were also studied. When the insoluble sericin was hydrolyzed with kojizyme and flavourzyme, the solubility was highest at pH 7 and 50$^{\circ}C$. On the other hand, in the cases of protamex and alcalase, the highest solubility was obtained at 60$^{\circ}C$. In these cases, solubility increased with pH. In enzymatic hydrolysis, the solubility was increased with concentration of enzymes until 4 hours. After then, a slight difference was found along with treatment times. In enzymatic hydrolysis, the absorbance of the soluble sericin was increased with concentration of enzymes and treatment times. Average degree of polymerization was decreased with treatment time and concentration. The amino acid compositions were similar in low(low molecular weight by degumming) and high (high molecular weight by degumming). Those of PK (soluble sericin hydrolyzed with kojizyme), PP (soluble sericin hydrolyzed with protamex), and PA(soluble sericin hydrolyzed with alcalase) were similar to each other. Serine and tyrosine compositions were higher in low and high than those of PK, PP, and PA. However proline was absent in low and high. Molecular weights of the various sericins became higher as KP>high>PP>low>PA and those of KP and PA were 9,800 and 905 respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.414.1-414.1
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• 2016

스크린 프린팅법을 이용한 태양전지의 전극은 주로 고가의 은을 사용하기에 태양전지의 저가화에 한계를 가지고 있다. 고효율 결정질 실리콘 태양전지의 원가절감의 문제 해결방안으로 박형 웨이퍼 연구개발이 많은 관심을 받고 있다. 본 연구에서는 은 전극을 대체 할 수 있는 니켈/구리 전극을 사용하였고, 박형 웨이퍼에서도 전극 공정이 가능한 도금법을 사용하여 전극을 형성 하였다. 니켈 전극형성은 광유도 도금법(Light-Induced Plating), 구리 전극형성은 광유도전해도금법(Light-Induced Electro Plating)을 이용하여 실험을 진행 하였다. 니켈 광유도 도금 공정시 공정시간 3 ~ 9분까지 가변하였다. 니켈실리사이드 형성 위해 열처리 공정을 $300{\sim}450^{\circ}C$까지 가변하였고 유지시간 30초 ~ 3분까지 가변하여 실험을 진행하였다. 니켈 도금 수용액의 pH 6 ~ 7.5까지 가변하여 실험하였다. 구리 광유도 전해도금 공정 전류밀도를 $1.6mA/cm^2{\sim}6.4mA/cm^2$까지 가변하여 실험을 진행 후, 전류밀도 $3.2mA/cm^2$로 시간 5 ~ 7분까지 가변하여 실험 하였다. 니켈 도금 공정 시간 5분, 니켈실리사이드 형성 열처리 온도 $350^{\circ}C$, 유지시간 1분에서 DIV(Dark I-V) 분석결과 가장 적은 누설전류를 확인하였다. 니켈 도금액 pH 6.5에서 니켈입자 및 구리입자의 균일성이 좋은 최적의 조건임을 확인하였다. 구리 도금 공정 전류밀도 $3.2mA/cm^2$, 시간 5분에서 TLM(Transmission Line Method) 측정결과 접촉 저항 $0.39{\Omega}$과 접촉 비저항 $12.3{\mu}{\Omega}{\cdot}cm^2$의 저항을 확인하였다. 도금법을 이용하여 전극을 형성함으로써 접촉저항 및 접촉 비저항이 낮고 전극 품질이 향상됨으로서 셀의 전류밀도 $42.49mA/cm^2$를 얻을 수 있었다.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.6-12
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• 2015

This study was performed to determine the optimal hydrolysis conditions for the production of hydrolysates, including water-soluble dietary fiber from Chinese cabbage, with commercial enzymes. The optimal pH and temperature for hydrolysis of the hemicellulose fraction were pH 5.0 and $40^{\circ}C$, and optimal enzyme concentrations were 45 units and 21 units for Shearzyme plus and Viscozyme L, respectively. The yields of the hydrolysate including the water-soluble dietary fiber from the hemicellulose fraction by Shearzyme plus and Viscozyme L were 22.64 and 24.73%, respectively, after a 72 h reaction. The molecular weight distribution of alcohol-insoluble fiber was characterized by gel chromatography; degradation of hemicellulose increased with increasing reaction time. Our results indicate that the hemicellulose fraction was degraded to water-soluble dietary fiber by enzymatic hydrolysis, and its hydrolysate could be utilized as new watersoluble food materials.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.451-459
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• 2002

High strength flour (12.5% protein) and low strength flour (10.5% protein)were used to determine optimum formulation far steamed bread added with green tea powder (GTP). The response surface study consisted of the following independent variables : GTP (1.5∼4.5%), mixing time (8∼14 min), fermentation time (30∼50min). Bread Quality attributes measured for total bread score of each combination were loaf volume, spread ratio, surface glossiness, smoothness, grain and texture (firmness, cohesiveness, elasticity and adhesiveness). The required amount of GTP, mixing time and fermentation time for steamed bread made from two kinds of flour were different. GTP could be more added to lower strength flour than higher strength flour without losing bread quality. GTP highly affected the loaf volume, spread ratio, surface smoothness, firmness and total bread score of steamed bread (p<0.001). The results suggested that the functional steamed bread added with GTP having excellent quality can be made from low strength flour using green tea powder 3.2%, mixing time 11 min 8 sec and fermentation time 39 min 55 sec.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.63-70
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• 2001

Changes in concentrations of dissolved oxygen, ammonia, nitrate, pH, Fe and Mn were monitored from the laboratory incubation of an benthic chamber. The extent of sedimentary organic carbon and nitrogen decomposition was quantified by applying the concentration data to the chemical reaction equations of early diagenesis. The patterns of the concentration changes, observed during the 237 hr long incubation experiment, made it possible to divide the entire experiment period into four characteristic sub-periods (0-9 hr, 9-45 hr, 45-141hr, 141-237 hr). C/N ratio, estimated for each sub-period, was 6.63, 1.49, 0.81 and 0.02, respectively. This sequential decrease in C/N ratio suggests that during the incubation experiment dissolved nitrogen species diffuse more out of the sediment than dissolved carbon species. Greater diffusion of nitrogen indicates the preferential decomposition of organic nitrogen during early diagenesis of sedimentary organic matter. Comparison of the concentration data (sedimentary organic carbon and nitrogen, porewater organic carbon and ammonia)between the sediment pre and post incubation also indicates the preferential decomposition of nitrogen during early diagenesis of sedimentary organic matter.