P2P 캐싱을 기반으로 한 효율적인 브로드캐스트 스트리밍 기법

이치훈,계이기,정인범,최창열,최황규 강원대학교 정보통신연구소 2006 정보통신논문지 Vol.10 No.-

Video-on-Demand is undoubtedly a promising technology for many important applications. Several periodic broadcast techniques have been proposed for the cost-effective implementation of such systems. However, there is a server delay for all of them. To address the shortcoming, we present a new scheme improving the staggered broadcasting by jointly using prefix caching scheme of VOD system in P2P environments. In thins paper, each client plays a role in the first segment staggered broadcasting server to serve the prefix stream to other clients that request the same video stream. The buffer can be empty after the client has served the following client. As a result, we are able to achieve no service latency time and the low buffer space.

Functional display of active tetrameric beta-galactosidase using Bacillus subtilis spore display system.

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>

Screening of Exiguobacterium acetylicum from Soil Samples Showing Enantioselective and Alkalotolerant Esterase Activity

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.

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.

Identification of ω-Aminotransferase from Caulobacter crescentus and Sitedirected Mutagenesis to Broaden Substrate Specificity

( 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.

팽이버섯으로부터 Lectin 의 정제와 특성

황세영,홍범식,손승렬,김형석 한국농화학회 1999 Applied Biological Chemistry (Appl Biol Chem) Vol.42 No.4

Two Lectins, designated FVL-1 and FVL-2, were isolated and purified from the fruiting bodies of edible mushroom Flammulina veluripes using ammonium sulfate fractionation, ethanol treatment, DEAE-TOYPEARL ion-exchange column chromatography, and TSK-Gel HW-55F column chromatography. Specific activity increased 18 folds for FVL-1 and 7.9 folds for FVL-2 from ethanol treated sample. SDS-PAGE of FVL-1 and FVL-2 gave apparent molecular mass of 10.6 kDa and 37 kDa, respectively. FVL-2 agglutinated all type of human erythrocytes (A, B, AB, and O). However, FVL-1 agglutinated more human erythrocyte type O than type A, B, and AB. The hemagglutination activities of the FVL-1 were effectively inhibited by bovine submaxillary and porcine stomach mucins(BSM and PSM), fetuin, asialofetuin and cations, such as Cu^(2+), Mg^(2+), Ca^(2+), Mn^(2+) and Fe^(2+). However, FVL-2 was not inhibited by any cations. The hemagglutination activities of the two lectins were not inhibited by the sugar, such as lactose, galactose and sugar derivatives. FVL-1 and FVL-2 were stable at pH 5∼11 and pH 4∼7, respectively. FVL-1 was stable below 55℃ and FVL-2 was below 45℃.

Anomalous behaviors of visible luminescence from graphene quantum dots: interplay between size and shape.

Kim, Sung,Hwang, Sung Won,Kim, Min-Kook,Shin, Dong Yeol,Shin, Dong Hee,Kim, Chang Oh,Yang, Seung Bum,Park, Jae Hee,Hwang, Euyheon,Choi, Suk-Ho,Ko, Geunwoo,Sim, Sunghyun,Sone, Cheolsoo,Choi, Hyoung Joo American Chemical Society 2012 ACS NANO Vol.6 No.9

<P>For the application of graphene quantum dots (GQDs) to optoelectronic nanodevices, it is of critical importance to understand the mechanisms which result in novel phenomena of their light absorption/emission. Here, we present size-dependent shape/edge-state variations of GQDs and visible photoluminescence (PL) showing anomalous size dependences. With varying the average size (d(a)) of GQDs from 5 to 35 nm, the peak energy of the absorption spectra monotonically decreases, while that of the visible PL spectra unusually shows nonmonotonic behaviors having a minimum at d(a) = ~17 nm. The PL behaviors can be attributed to the novel feature of GQDs, that is, the circular-to-polygonal-shape and corresponding edge-state variations of GQDs at d(a) = ~17 nm as the GQD size increases, as demonstrated by high-resolution transmission electron microscopy.</P>

적응 프루닝 알고리즘과 PDT-SSS 알고리즘을 이용한 한국어 연속음성인식에 관한 연구

황철준(Chul-Joon Hwang),오세진(Se-Jin Oh),김범국(Bum-Koog Kim),정호열(Ho-Youl Jung),정현열(Hyun-Yeol Chung) 한국멀티미디어학회 2001 멀티미디어학회논문지 Vol.4 No.6

한국어 주소 음성인식의 고속화을 위한 프레임 단위 적응 프루닝 알고리즘

황철준(Cheol Jun Hwang),오세진(Se Jin Oh),김범국(Bum Koog Kim),정현열(Hyun Yeol Chung) 영남대학교 정보통신연구소 2000 정보통신연구소논문집 Vol.7 No.1

호르몬 불응성 전립선암 환자에서 mitoxantrone과 prednisone의 병합화학요법 후 통증완화 및 삶의 질 측정

이홍우,이지열,김세웅,이충범,강성학,조용현,황태곤,박용현,윤문수 대한화학요법학회 2000 대한화학요법학회지 Vol.18 No.3

목적 : 호르몬 불응성 전립선암 환자의 생명을 연장시키는 치료법은 현재로는 없으며, 현 시점에서의 치료목표는 증상의 경감 및 소실에 따른 삶의 질 향상에 두고 있다. 호르몬 불응성 전립선암의 고식적인 치료에 일차적인 치료법으로 간주되는 mitoxantrone과 prednisone의 화학요법이 호르몬 불응성 전립선암 환자의 통증완화 및 삶의 질에 어떠한 영향을 미치는지 알아보았다. 방법 : 1998년 7월부터 1999년 12월까지 증상이 있는 18명의 호르몬 불응성 전립선암 환자를 대상으로 하였으며, 일차적인 치료의 목표는 환자 본인이 기록하는 McGill-Melzack 6단계 통증척도에서 진통제의 증량 없이 2점이 감소(또는 첫 점수가 1점일 경우 통증의 완전소실)하는 것으로 하였다. 이러한 기준은 최소 3주 간격으로 시행한 자가 기록조사에서 연속적으로 2번 이상 유지될 때 유효한 것으로 간주하였다. 건강과 관련된 삶의 질 측정은 전신적 치료의 임상적 응용을 위한 실제적인 측정방법으로 개발되어 환자가 직접 작성하는 전립선암 특이성 삶의 질 측정기구(Prostate Cancer-Specific Quality-of-Life Instrument : PROSQOLI)의 비례연속형의 자가측정 척도(linear analogue self-assessment scale : LASA)를 이용하였으며, ECOG performance status를 사용하여 전신상태의 변화도 측정하였다. 결과 : 통증의 경감으로 나타나는 고식적인 치료의 반응은 66.7%(12/18)에서 나타났으며, 반응의 지속기간은 2개월에서 10개월까지로 평균 4.2±3.6개월이었다. PROSQOLI로 측정한 삶의 질은 통증에 대한 고식적인 치료반응을 보인 12명(66.7%) 모두가 삶의 질이 개선되었으며 특히 통증, 변비, 소변보기, 전반적인 복지상태에서의 유의한(p<0.05) 증가를 보였다. 치료 후 혈장 PSA 수치는 고식적인 반응의 유무에 관계없이 별 다른 변화를 보이지 않았으며, 골주사 또는 전산화 단층촬영으로 측정한 방사선학적 병변은 고식적인 반응을 보인 2명을 제외하고 치료 전과 비교하여 차이를 보이지 않았다. 병합 화학요법과 관련된 특별한 부작용은 관찰되지 않았다. 결론 : 통증을 동반한 호르몬 불응성 전립선암에서 mitoxantrone과 prednisone의 병합화학요법은 66.7%의 환자에서 통증의 감소 및 삶의 질이 향상되었다. 현재는 혈장 PSA 수치, 병소의 크기나 개수등이 치료의 지침이나 치료결과의 판정을 위한 객관적인 기준으로 사용되는 경향이 있지만, 앞으로는 환자를 중심으로 통증을 포함한 삶의 질 측정이 고식적 치료 후 치료결과 판정에 있어 객관적이고 적절한 방법이 될 것이다. Background : There is no evidence that therapeutic modalities prolong the survival of patients with hormone-refractory prostate cancer nowadays. The main goal of treatment is therefore improvement in quality-of-life including palliation of symptoms. We performed this study to investigate the benefit of mitoxantrone and prednisone chemotherapy in patients with symptomatic hormone-refractory prostate cancer using relevant end points of palliation regarding to pain and quality-of-life. Methods : From July 1998 to December 1999, we assessed the 18 patients with symptomatic hormone-refractory prostate cancer receiving mitoxantrone and low dose prednisone. The treatment end point was a palliative response defined as a 2-point decrease in pain assessed by a 6-point pain scale complemented by patients (or complete loss of pain if initially 1+) without an increase in analgesic medication and maintained for two consecutive evaluations at least 3 weeks apart. Health-related quality-of-life was evaluated with a series of linear analogue self-assessment(LASA) scale of the Prostate Cancer-Specific Quality-of-Life Instrument (PROSQOLI) and performance status was also measured. Results : Palliative responses were observed in 12(66.7%) of 18 patients. The duration of palliative responses were 4.2±3.6 months(range: 2 to 10 months). Treatment was well tolerated without specific side effects. There were no differences in prostate-specific antigen (PSA) level following treatment and no significant changes of radiologic findings evaluated by bone scan and/or CT were noted except 2 cases after chemotherapy. All the responding patients had an improvement in quality-of-life scales and performance status, however serum PSA levels were not changed. Conclusions : Chemotherapy with mitoxantrone and prednisone provides palliation and an improvement in quality-of-life for more than half (66.7%) of the patients with symptomatic hormone-refractory prostate cancer.