• 공업화학
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• 제2권2호
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• pp.108-118
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• 1991

황화 $CoMo/{\gamma}-Al_2O_3$ 촉매를 사용하여 473~723K의 온도와 $10{\sim}15{\times}10^5Pa$의 압력 그리고 접촉시간 0.0125~0.03 g-cat hr/ml-feed 범위에서 pyridin의 수첨탈질반응과 m-cresol의 수첨탈산소 반응의 상호작용 및 그 속도론에 관하여 연구하였다. Pyridin의 수첨탈질반응과 m-cresol의 소첨탈산소 반응의 상호반응을 저지억제하였으며, pyridin에 의한 m-cresol의 수첨탈산소반응의 억제효과는 m-cresol에 의한 pyridin의 수첨탈질반응의 억제효과보다 더 컸으나 반응성은 m-cresol이 더 높았다. Pyridin의 수첨탈질반응 속도식 및 m-cresol의 수첨탈산소반응 속도식을 LHHW 모델을 이용하여 구한 결과 ${\gamma}_{HDN}=k_{HDN}{\cdot}K_pC_p/(1+K_cC_c+K_pC_p)$, ${\gamma}_{HDO}=k_{HDO}{\cdot}K_cC_c/(1+K_cC_c+K_pC_p)$였다. 각 온도에서 반응속도상수 및 흡착평형상수를 구하여 Arrhenius plot 과 Van't Hoff plot을 행하여 구한 활성화 에너지값은 pyridin과 m-cresol이 각각 16.21 Kcal/mole, 13.83 Kcal/mole이었고, 흡착열은 각각 -6.458 Kcal/mole, -5.045 Kcal/mole이었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제3권1호
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• pp.44-47
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• 1998

Maximum cellulase production was sought by comparing the activities of the cellulases produced by different Trichoderma reesei strains and Aspergillus niger. Trichoderma reesei Rut-C30 showed higher cellulase activity than other Trichoderma reesei stains and Aspergillus niger that was isolated from soil. By optimizing the cultivation conditions during shake flask culture, higher cellulase production could be achieved. The FP(filter paper) activity of 3.7U/ml and CMCase (Carboxymethylcellulase) activity of 60U/ml were obtained from shake flask culture. When it was grown in 2.5L fermentor, where pH and DO levels are controlled, the enzyme activities were 133.35U/ml (CMCase) and 11.67U/ml(FP), respectively. Ammonium sulfate precipitation method was used to recover enzymes from fermentation broth. The dried cellulase powder showed 3074.9U/g of CMCase activity and 166.7U/g of FP activity with 83.5% CMCase recovery.

• Imaging Science in Dentistry
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• 제32권4호
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• pp.213-219
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• 2002

Purpose : Computed radiography (CR) has been used in cephalometric radiography and many studies have been carried out to improve image quality using various digital enhancement and filtering techniques, During CR image acquisition, the frequency rank and type affect to the image quality. The aim of this study was to compare the diagnostic quality of conventional cephalometric radiographs to those of computed radiography. Materials and Methods : The diagnostic quality of conventional cephalometric radiographs (MO) and their digital image counterparts were compared, and at the same time, six modalities (M1-M6) of spatial frequency-processed digital images were compared by evaluating the reproducibility of 23 cephalometric landmark locations. Reproducibility was defined as an observer's deviation (in mm) from the mean between all observers. Results and Conclusion: In comparison with the conventional cephalometric radiograph (MO), Ml showed statistically significant differences in 8 locations, M2 in 9, M3 12, M4 in 7, M5 in 12, and M6 showed significant differences in 14 of 23 landmark locations (p < 0.05). The number of reproducible landmarks that each modality possesses were 7 in M6, 6 in M5, 5 in M3, 4 in M4, 3 in M2, 2 in Ml, and 1 location in MO. The image modality that observers selected as having the best image quality was M5.

• 생명과학회지
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• 제15권5호
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• pp.796-801
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• 2005

국내산 산죽잎을 methanol로 추출하여 천연 항산화제로서의 이용성을 조사하기 위하여 여러 방법으로 항산화 활성을 측정하고 안정성에 대해 조사하였다. 산죽잎 메탄올 추출물은 0.1 mg/l에서 0.8mg/ml의 범위에서 농도 의존적으로 항산화활성이 증가하였다. 산죽잎 메탄올추출물은 DPPH radical 소거능에 대한 $IC_{50}$ 값은 $583{\mu}g/ml$, SOD 유사활성능에 대한 $IC_{50}$값은 $800{\mu}g/ml$, hydrogen peroxide 소거능에 대한 $IC_{50}$값은 $38{\mug}/ml$이 었으며 대조구로 사용한 BHT의 각각 의 $IC_{50}$값은 $271{\mu}g/ml,{\;}680{\mu}g/ml,{\;}30{\mu}g/ml$이었다. 산죽잎 메탄올추출물의 자동산화 억제능은 상기 농도 범위에서 $55\∼60\%$의 억제효과를 나타내었다. 산죽잎 메탄올추출물의 pH 안정성은 pH 6에서 안정하였으나 산성이나 알카리성으로 갈수록 pH 안정성은 떨어졌다. 산죽잎 메탄올추출물의 열안정성은 $0^{\circ}C$에서 $120^{\circ}C$의 온도범위에서 $80\%$ 이상의 항산화능을 유지하였다.

• 한국균학회지
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• 제26권2호통권85호
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• pp.239-245
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• 1998

섬유소를 분해하여 이용하기 위해서는 섬유소 분해효소를 대량으로 생산하는 것이 중요하며 이를 위해서는 적절한 탄소원을 이용하여 섬유소 분해효소의 대량생산을 유도하는 것이 중요하다. 본 실험에서는 Trichoderma reesei Rut C-30을 섬유소 분해효소의 생산 균주로 solka floc을 탄소원으로 사용하여 섬유소 분해효소의 활성을 증가시키기 위한 배지내 최적 농도가 1%이고 포도당이 0.5%이상 배지에 첨가 될 경우 섬유소 분해효소의 생산이 저해됨을 알 수 있었다. 정제된 섬유소인 solka floc이 목질섬유소인 wheat bran과 함께 탄소원으로 사용되었을 때 각각을 섬유소 분해효소 생산의 유도 물질로 이용했을 때보다 더 높은 CMCase 활성과 FPase 활성을 보였다. Solka floe 1%와 wheat bran 3%을 탄소원으로 사용한 배지의 CMCase 활성이 76 U/ml, FPase 활성이 12.6 U/ml로 가장 높은 값을 나타내었다.

• 대한기계학회논문집A
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• 제22권1호
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• pp.177-189
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• 1998

The contents of this paper include a non-destructive technique for evaluating the degradation of the boiler superheater tube in a fossil power plant through an electrochemical polarization test. Correlation between Ip of polarization parameter and SP-DBTT for the superheater tubes in long-term use was obtained. 1.0Cr-0.5Mo steel was degraded by softening, and the degree of degradation was dependent upon carbides with Cr and Mo elements. Since brittle fracture at low temperature and ductile fracture mode at high temperature were shown, similarity between standard Charpy and small punch tests could be found. In addition, SP-DBTT showing the degree of degradation was higher, as the time-in use of the materials got longer. Electrolyte including picric acid of 1.3 g in distilled water of 100ml at 25.deg. C temperature and sodium tridecylbenzene sulfonate with 1g could be applied to evaluate the degradation of 1.0Cr-0.5Mo steel by means of the electrochemical polarization test. Ip and Ipa values measured through the electrochemical test are the appropriate parameters for representing the degradation of the superheater tube(1.0Cr-0.5Mo steel) for the fossil power plant. It is poassible to evaluate the degradation of materials with different time histories electrochemically, by Ip value only, at field test.

• 한국자원식물학회지
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• 제26권1호
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• pp.44-51
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• 2013

본 연구에서는 파극천 추출물의 수면연장 시간, 항 경련효과 및 시험관내에서 파극천의 각 분획별 활성산소의 소거능을 관찰하여 본 결과 pentobarbital을 투여한 대조군의 수면 유도시간 및 수면시간($3.77{\pm}0.56$분, 수면시간 $68.3{\pm}6.8$분)이 파극천 추출물(200 mg/kg)을 전 처리하고 pentobarbital을 투여함으로써 수면유도 시간($3.95{\pm}0.56$분) 및 수면시간($110.4{\pm}10.3$분)이 연장되었다. PTZ에 의해 유도되는 경련 발작이 대조군 $4.9{\pm}0.98$인데 비해 파극천(200 mg/kg)의 전처리로 경련박작이 $3.2{\pm}0.54$로 현저히 억제되었으며 이 결과는 PTZ의 경련발현시간, 경련유지시간 및 사망시간에 미치는 파극천의 영향과 유사하였다. 뇌중 GABA 함량은 PTZ의 투여로 정상군에 비하여 억제되던 것이 파극천의 전처리로 증가 되었으며, GABA-T의 활성과 지질과산화의 함량은 PTZ의 투여로 각각 증가되던 것이 파극천 추출물의 투여로 억제되었다. 시험관내에서 PTZ로 유도된 뇌조직중의 hydroxy radical의 생성량은 butanol 및 dichlomethane 분획의 첨가($20{\times}10^{-2}g/ml$)에서 약 35%에서 50%까지 감소하였다.

• Journal of Microbiology and Biotechnology
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• 제11권2호
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• pp.229-233
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• 2001

Trichoderma reesei Rut C-30 produced high levels of ${\beta}$-glucosidase, endo-${\beta}$-glucosidase, endo-${\beta}$-1,4-glucanase, and exo-${\beta}$-1,4-glucanase. In pilot-scale production (50-1 fermentor), productivity and yield of CMCase (carborymethyl cellulose) and FPase (filter paper activity) were 273 U/ml and 35 U/ml, and 162 FPU/l.h and 437 FPU/g, respectively. The fed-batch techniques were used to improve enzyme activities with constant cell concentration. The acidity was an important parameter and controlled at pH 3.9 and 5.0 by automatic addition of ammonium hydroxide. Cellulase powder was prepared by ammonium sulfate precipitation and its CMCase and FPase activities were 3,631 U/g and 407 U/g, respectively.

• Journal of Microbiology and Biotechnology
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• 제9권1호
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• pp.44-49
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• 1999

Cellulase production by fed-batch cultivation of Trichoderma reesei Rut C30 with various initial concentrations of Solka Floc in 1 % wheat bran-containing medium was investigated. The cellulase activity and productivity increased with initial Solka Floc concentration up to 5%. When a total Solka Floc concentration of 90 g/l was used for cellulase production, CMC (carboxymethyl cellulose) and FP (filter paper) activities, productivity, and yield were 359.7 U/ml, 30.61 U/ml, 161 FPU $L^{-1}$ $h^{-1}$, and 340 FPU $g^{-1}$, respectively. It was important to maintain a high cell concentration during cellulase production to obtain high cellulase activity and productivity. Cellulase powder was prepared by ammonium sulfate precipitation: FP activity was 396.7 U/g and CMC activity was 6481 U/g.

• Journal of Microbiology and Biotechnology
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• 제8권3호
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• pp.208-213
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• 1998

The effect of the addition of wheat bran to the growth medium on the production of cellulolytic enzymes of Trichoderma reesei Rut C30 was studied in batch culture using shake flasks. The activity of cellulase was enhanced by the addition of wheat bran to the cellulase production medium. $KH_2PO_4$-$K_2HPO_4$ buffer was used for pH control during cellulase production. As a result, high cellulase activities were obtained in shake flask culture; a CMC (carboxymethyl cellulose) activity of 125.78 U/ml was obtained from 2% Avicel- and 3% wheat bran-containing medium and an FP (filter paper) activity of 12.85U/ml was obtained from 1% Avicel- and 5% wheat bran-containing medium after 6 days of cultivation.