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권호열,전진화,김범규 강원대학교 정보통신연구소 1998 정보통신논문지 Vol.2 No.-
Carrierless Amplitude Modulation/Phase Modulation(CAP) has the same spectral characteristics and provides the same theoretical performance as QAM, but is generally less complex to implement digitally. In this paper, a 52 Mbps CAP transceiver system is modeled and simulated according to DAVIC VDSL standard. Also we analyzed error rate characteristics under AWGN channel by using MATLAB.
치과용 콤포짓트 레진의 적정중합을 위한 최소 광조사 시간 평가
임범순,이용근,김철위,최기열,이중배 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.1
The aim of this study was to estimate the minimum irradiation time for dental composites using a dynamic mechanical analyzer (DMA) and FT-IR. Six commercially available dental composites with A3 shade were tested: Heliomolar RO (Vivadent, Liechtenstein), Charisma (Kulzer, Germany), Herculite XRV Enamel (Kerr, USA), Aelitefil (Bisco, USA), Z100 (3M, USA), and Z250 (3M, USA). Storage modulus was measured by using DMA (StressTech Rheometer, Rheologica Instrument, Sweden) with fast oscillation mode (1 Hz). After disk-type (4 ㎜ ?1 ㎜) samples were irradiated with 500 mW/cm2 for 1, 2, 3, 4, 5, 10, 15, 20, and 30 s, storage modulus was recorded continuously for 60 min. Degree of conversion was also measured using FT-IR spectroscopy (FTS-165, Biorad Win-IR, Perkin-Elmer, USA) at 60 min after irradiation with same curing condition as DMA test. Sample irradiated with 500 mW/cm2 for 120 s was used as a control. The average of results for five specimens was compared using Tukey multiple comparison test (p=0.05) and the minimum irradiation time of composites was determined. The minimum irradiation time to get adequate polymerization was different depending on the dental composites. Both Z100 and Z250 require short irradiation times (5 s) and Charisma requires long irradiation time (15 s).
광도와 온도가 가시광선 중합형 치과용 레진의 중합에 주는 영향
이종근,최주열,임범순,신현철 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.4
본 연구에서는 2종의 다이메타크릴레이트 치과용 레진 (urethane dimethacylate, UDMA와 bisphenol A glycerolate dimethacylate, Bis-GMA)이 광중합 반응하는 과정에서 변화되는 물성을 동역학분석법 (dynamic mechanical analysis, DMA)으로 관찰하였다. 광중합에 사용한 가시광선 (λ=400-500 nm)의 광도는 20 mW/㎠에서 70, 120, 300 및 600 mW/㎠로 변화시켜 그에 따른 저장탄성율 (storage modulus, G')과 손실탄성율 (loss modulus, G")의 변화를 측정하였고, 측정온도도 25 ℃에서 37, 50 및 60 ℃로 변화시켜 온도가 중합과정에 주는 영향을 관찰하였다. 광조사 시간은 모든 시편에 대하여 측정 시작 직후 30초로 일정하게 하였다. 각 조건에서 측정한 G' 과 tan δ (=G"/G') 결과를 이용하여 겔화 (gelation)와 유리화 (vitrification) 전이시점 (transition point)을 결정하였으며, 이를 이용하여 TTIT (Time-Temperature-Intensity-Transformation) 중합 도표를 작성하였다. 이 중합도표를 보면 광도 변화가 온도 변화보다 중합반응에 더 민감하게 영향을 주었으며, 특히 광도는 겔화보다 유리화에 훨씬 크게 영향을 주는 것을 알 수 있었다.
김시욱,이정섭,정해광,박열,윤성명,유진철,이범규,이인화,박진열 조선대학교 환경공해연구소 1998 環境公害硏究 Vol.14 No.-
UV-TiO_(2) 반응기를 이용하여 Escherichia coli와 Aspergillus oryzae var. oryzae의 살균효과를 측정하였다. 254 ㎚에서 최대 14 watt의 자외선 방출량을 내는 램프를 원형 Pyrex유리관 중앙에 설치하였고 TiO_(2)는 석영관에 박막증착(Thin Film Coating)된 형태와 슬러리 형태로 나누어 회분식으로 살균정도를 측정하였다. E. coli에 대한 살균력은 1.7× 10^(7) cells/㎖에 대해 5분간 자외선 조사를 하였을 경우 2.0× 10^(2) cells/㎖으로 감소하였고, 자외선 조사와 함께 슬러리 형태의 TiO_(2)를 첨가하였을 경우에는 3.4× 10 cells/㎖으로, 자외선 조사와 함께 TiO_(2)가 석영관에 박막증착된 경우에는 7.6× 10^(2) cells/㎖으로 감소하였다. 한편 위와 같은 조건에 유리관 하부에서 기포를 주입후 11분 동안 자외선을 조사시킨 경우에는 1.3× 10^(2) cells/㎖으로, 자외선 조사와 함께 슬러리 형태의 TiO_(2)를 첨가하였을 경우에는 1× 100 cells/㎖으로, 자외선 조사와 함께 TiO_(2)가 박막증착된 경우에는 7.9× 10 cells/㎖을 나타내었다. 결국 UV-TiO_(2) 반응기에 사용되는 TiO_(2)가 슬러리 형태일 때 최대 살균효과를 나타내었으나 기포가 첨가되었을때는 오히려 살균에 장애를 받는 것으로 나타난 반면 석영관에 박막증착된 경우에는 기포가 첨가되는 것이 살균에 효과적인 것으로 관찰되었다. The killing effect of UV-TiO_(2) photocatalytic system on the Escherichia coli DH5-慣 and Aspergillus oryzae var. oryzae (KCTC 6095) was studied. The UV lamp which emits maximum 14 watts at 254 nm was set on the center of pyrex round glass tube. Two types of TiO_(2), one of which is slurry and another which is thin film coated form, were used to determine the killing effect. When UV was irradiated to 1.7 * 10^(5) cells/??of E. coli for 11 min, the living cell number decreased to 4.0 * 1.0^(0) cells/?? The effect of UV system together with slurried TiO_(2) was less than 1 cells/?? whereas that of UV-coated TiO_(2) system decreased to 7.1 * 10^(3) cells/?? To study the effect of bubble on the killing of microorganisms, air was bubbled to the bottom of glass tube. When 1.7 * 10^(5) cells/??were exposed to UV for 11 min in combination with air bubble, the living cell number decreased to 1.3 x 10^(2) cells/?? In the same condition except the addition of slurried TiO_(2), the living cells were 1 * 10^(2) cells/?? However, more cells could be killed by the system which consists of UV, coated TiO_(2), and air bubble (7.9 * 10^(1) cells/??. From these results, it was found that UV-slurried system is the most effective one, but its killing effect is not stimulated by air bubble. However, bubbling was very effective in the UV-coated TiO_(2) system.
Directed Evolution of Cutinase Using In vitro Compartmentalization
Bum-Yeol Hwang 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.3
High-throughput screening (HTS) is a key step to the success of directed evolution of enzymes. Recently,fluorescence-activated cell sorting (FACS) has emerged as a promising tool for HTS. Directed evolution of Fusarium solani cutinase, which is partially released from E. coli cells, was carried out using a FACS-based screening technique to increase its activity for (R)-flurbiprofen. First,the ability of using the FACS-based screening technique to screen active cutinase using wild type cutinase (WT) and inactivated cutinase mutant (S42A) was examined. Although the FACS-based screening using E. coli cells did not work well due to the diffusion of fluorescent product and/or an interference by the partially released cutinase from the the cells, FACS could be used to effectively screen active wild type cutinase via in vitro compartmentalization using water/oil/water emulsion microcompartments. Cutinase variants showing higher activity for (R)-flurbiprofen could be screened after four screening steps. The mutants 2-95 and 0-5 showed 8.0- and 6.8-fold higher activities for fluorescein (R)-flurbiprofen diester compared to that of the wild type cutinase, respectively. The mutant 0-5 also showed 5.0-fold higher activities for fluorescein butyl diester compared to that of the wild type cutinase.
( Bum Yeol Hwang ),( Seung Hyun Ko ),( Hyung Yeon Park ),( Joo Hyun Seo ),( Bon Su Lee ),( Byung Gee Kim ) 한국미생물 · 생명공학회 2008 Journal of microbiology and biotechnology Vol.18 No.1
A putative ω-aminotransferase gene, cc3143 (aptA), from Caulobacter crescentus was screened by bioinformatical tools and overexpressed in E. coli, and the substrate specificity of the ω-aminotransferase was investigated. AptA showed high activity for short-chain β-amino acids. It showed the highest activity for 3-amino-n-butyric acid. It showed higher activity toward aromatic amines than aliphatic amines. The 3D model of the ω-aminotransferase was constructed by homology modeling using a dialkylglycine decarboxylase (PDB ID: 1DGE) as a template. Then, the ω-aminotransferase was rationally redesigned to increase the activity for 3-amino-3-phenylpropionic acid. The mutants N285A and V227G increased the relative activity for 3-amino-3-phenylpropionic acid to 3-amino-n-butyric acid by 11-fold and 3-fold, respectively, over that of wild type.
Hwang Bum-Yeol,Kim Ji-Hyun,Kim Juhan,Kim Byung-Gee The Korean Society for Biotechnology and Bioengine 2005 Biotechnology and Bioprocess Engineering Vol.10 No.4
About 3,000 bacterial colonies with esterase activities were isolated from soil samples by enrichment culture and halo-size on Luria broth-tributyrin (LT) plates. The colonies were assayed for esterase activity in microtiter plates using enantiomerically pure (R)- and (S)-2-phenylbutyric acid resorufin ester (2PB-O-res) as substrates. Two enantioselective strains (JH2 and JH13) were selected by the ratio of initial rate of hydrolysis of enantiomerically pure (R)- and (S)-2-PB-O-res. When cell pellets were used, both strains showed high apparent enantioselectivity ($E_{app}>100$) for (R)-2PB-O-res and were identified as Exiguobacterium acetylicum. The JH13 strain showed high esterase activity on p-nitrophenyl acetate (pNPA), but showed low lipase activity on p-nitrophenyl palmitate (pNPP). The esterase was located in the soluble fraction of the cell extract. The crude intracellular enzyme preparation was stable at a pH range from 6.0 to 11.0.
Hwang, Bum-Yeol,Pan, Jae-Gu,Kim, Byung-Gee,Kim, June-Hyung American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.3
<P>For the functional bacterial surface display of active enzyme of multimeric form, which is generally impossible due to molecular assembly of the monomer subunit subsequent to the secretion of displayed target protein outside the cell, a new surface display system based on B. subtilis spore was developed. Using cotE and cotG of B. subtilis as anchoring motives, beta-galactosidase, which is active in tetrameric form, was functionally displayed on the surface of B. subtilis spore. The surface localization of beta-galactosidase was verified by Miller assay of purified spore, protease accessibility test of purified spore, and flow cytometric analysis of spore expressing beta-galactosidase. While B. subtilis spore wall integrity, examined by lysozyme and heat treatments, was affected by the incorporation of CotE-LacZ fusion protein, it was not affected by the incorporation of CotG-lacZ fusion. Heat stability of displayed protein was similar with that of free enzyme.</P>