• Natural Product Sciences
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• 제14권4호
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• pp.254-259
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• 2008

An easy and reliable HPLC method was developed to determine allantoin in Dioscorea Rhizoma using cyano columns. Qualitative and quantitative analyses of allantoin were performed successfully by cyano columns (YMC-Pack CN column, Zorbax SB-CN column and Discovery$^{(R)}$ Cyano column). The intraday precision were 0.58 - 3.33% for YMC-Pack CN, 0.41 - 2.20 for Zorbax SB-CN and 0.45 - 1.93% Discovery$^{(R)}$ Cyano columns, while interday variations were 0.09 - 1.84%, 0.04 - 2.59% and 0.87 - 5.18% for YMC-Pack CN, Zorbax SB-CN and Discovery$^{(R)}$ Cyano columns. The recoveries of allantoin were in the range at 98.8 - 102.6% (RSD 1.1 - 1.6%) for YMC-Pack CN column, 99.7 - 110.5% (RSD 1.3 - 4.9%) for Zorbax SB-CN column, and 97.2 - 110.1% (RSD 1.8 - 5.7%) for Discovery$^{(R)}$ Cyano column. The contents of allantoin in four Dioscorea Rhizoma samples were determined by cyano columms and ranged at 4.1-7.1 mg/g dry weight. The present study indicated that HPLC method using cyano column for determining allantoin is a reliable method and this method can be applied to verify allantoin in Dioscorea Rhizoma.

• Journal of Genetic Medicine
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• 제12권2호
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• pp.72-78
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• 2015

Recently, noninvasive prenatal test (NIPT) has been adopted as a primary screening tool for fetal chromosomal aneuploidy. The principle of NIPT lies in isolating the fetal fraction of cell-free DNA in maternal plasma and analyzing it with bioinformatic tools to measure the amount of gene from the target chromosome, such as chromosomes 21, 18, and 13. NIPT will contribute to decreasing the need for unnecessary invasive procedures, including amniocentesis and chorionic villi sampling, for confirming fetal aneuploidy because of its higher positive predictive value than that of the conventional prenatal screening method. However, its greater cost than that of the current antenatal screening protocol may be an obstacle to the adoption of this innovative technique in clinical practice. Digital polymerase chain reaction (dPCR) is a novel approach for detecting and quantifying nucleic acid. dPCR provides real-time diagnostic advantages with higher sensitivity, accuracy, and absolute quantification than conventional quantitative PCR. Since the groundbreaking discovery that fetal cell-free nucleic acid exists in maternal plasma was reported, dPCR has been used for the quantification of fetal DNA and for screening for fetal aneuploidy. It has been suggested that dPCR will decrease the cost by targeting specific sequences in the target chromosome, and dPCR-based noninvasive testing will facilitate progress toward the implementation of a noninvasive approach for screening for trisomy 21, 18, and 13. In this review, we highlight the principle of dPCR and discuss its future implications in clinical practice.

• Journal of Communications and Networks
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• 제6권4호
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• pp.387-396
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• 2004

One of the main problems associated with MANETs is that mobility and the associated route discovery and maintenance procedures of reactive routing protocols cause severe interruptions on real-time video streams. Some of these interruptions are too large to be concealed using any sort of video technology, resulting in communications breaks unpleasant for the final end user. We present a solution for enhanced video transmission that increases route stability by using an improved route discovery process based on the DSR routing protocol, along with traffic splitting algorithms and a preventive route discovery mechanism. We also present some video adaptative mechanisms that improve the overall performance of multipath routing in terms of video data replication and video packet splitting strategies. Combining our proposals, we achieve up to 97% less interruptions on communication with high mobility and over 1.2 dB of improvements in terms of video distortion.

• 생약학회지
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• 제42권2호
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• pp.110-116
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• 2011

As part of our ongoing study focused on the discovery of antioxidants from natural products by measuring the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity, methanol extract of flowers of Carthamus tinctorius L. was found to show potent antioxidant activity. Activity-guided fractionation of the methanol extract lead to the isolation of twenty compounds including two flavonol glycosides, quercertin-3-O-${\beta}$-D-glucopyranoside (12) and kaempferol-3-O-${\alpha}$-L-rhamnopyranosyl-${\beta}$-D-glucopyranoside (18), two flavanone glycosides, (2S)-4',5,6,7-tetrahydroxyflavanone 6-O-${\beta}$-D-glucopyranoside (15) and (2R)-5,7,8',4-tetrahydroxyflavanone 8-O-${\beta}$-D-glucopyranoside (16), and two acetylenic glycosides, 8Z-decaene-4,6-diyne-1-O-${\beta}$-D-glucopyranoside (13) and 4,6-decadiyne-1-O-${\beta}$-D-glucopyranoside (14). Their chemical structures were identified by using spectroscopic analysis. Among them, compounds 12-18 were tested in DPPH assay. Compounds 13-16 were first reported to their antioxidant activity. Quercertin-3-O-${\beta}$-D-glucopyranoside (12) showed the most potent inhibitory effect on DPPH with $IC_{50}$ value of 56.7 ${\mu}M$.

• 대한화학회지
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• 제54권1호
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• pp.77-87
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• 2010

40여년전에 보고된 이래 병원에서 유래한 메치실린-저항 Staphylococcus aureus (MRSA) 은 세계적으로 큰 문제가 되어왔다. 항균성의 가능성을 가지는 새로운 약품을 개발하기 위하여 N'-[(-3-substituted-4-oxo-1,3-thiazolidin-2-ylidene]-4-hydroxy benzohydrazide (4a-4.i)와 N'-[-(3,4-disubstituted)-1,3-thiazolidin-2ylidene)]-4-hydroxybenzohydrazide (5.a-5.i)~(10.a-10.i)을 적절한 합성방법을 사용하여 합성하였다. 이들 합성된 화합물들은 s. aureus 균주에 대해 생체외 조건에서 분석하였다. 시료 화합물과 표준 화합물에 대해 최소억제농도(MIC)를 결정하였다. 시험한 모든 화합물들은 2000 ${\mu}g$/mL 투여량까지는 독성이 없었고, 사용한 균주에 대해 상당한 항균성을 보였다. 특히 6.f, 7.g, 9.f 와 10.f, 10 i 들이 가장 항균성이 컸다. 이것으로 미루어 파라-히드록시벤조히드라자이드 고리와 치환된 싸이아졸린 고리는 항균성에 필수적임을 알 수 있었다. 3D-QSAR 분석결과로 파라-히드록시벤조히드라자이드의 활성자리에 대한 결합방식을 알게되었다.

• 농약과학회지
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• 제11권4호
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• pp.313-319
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• 2007

2,4-D를 비롯한 9종의 식물생장조절제를 선발하여 벼 도열병에 대한 방제 효과를 실험하였다. 각각의 식물생장조절제를 $500\;{\mu}g\;mL^{-1}$의 농도로 조절하여 벼의 유묘에 경엽처리하였을 경우, 2,4-D만 98.9%의 효과를 보였을 뿐, 나머지의 식물생장조절제는 50% 이하의 낮은 효과, 또는 무처리구보다도 높은 발병율을 보였다. 하지만 토양에 관주처리하였을 경우에는 2,4-D, indole butyric acid, triiodebenzoic acid가 98.9, 97.8, 88.9%의 효과를 보였으며, ethephone과 abscisic acid는 50%의 효과를 보였다. IBA를 토양 관주처리하였을 때 벼 도열병에 대한 효과는 처리한 농도에 비례하였는데, 125와 $250\;{\mu}g\;mL^{-1}$의 처리에서는 벼 도열병의 발생을 71.7과 85.8% 억제하였다. 벼 성체 식물에 2.56 kg/10a의 수준으로 토양 관주처리하였을 경우에는 63.9%의 방제효과를 보였다. 이상의 결과에서 IBA는 토양 관주처리에 의해서 벼 도열병에 대한 효과가 우수한 것으로 판명되었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 춘계학술대회
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• pp.126-129
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• 2015

최근 단말간 직접 통신이 가능한 단말대단말 통신 기술이 많은 관심을 받고 있다. 따라서 단말대단말 기술이 셀룰러 통신 시스템 및 차량 통신 시스템에 접목되고 있다. 본 논문에서는 Evolved Packet Core Network 기반 단말 탐색 시뮬레이터 개발에 대해서 살펴보고, Proximity기반 서비스의 차량간 애드혹 네트워크로의 적용 가능성에 대해서 살펴보았다. 개발된 시뮬레이터를 활용한 성능 분석을 통해서 유저들이 비슷한 위치에 모여 있는 환경, 즉대중교통과 비슷한 환경에서 LTE 네트워크의 트래픽이 Wi-Fi통해 단말대단말 통신으로 효율적으로 오프로딩될 수 있고 교통 관련 정보 멀티캐스팅에 효율적으로 활용될 수 있음을 보였다.

• 정보처리학회논문지D
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• 제10D권2호
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• pp.277-282
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• 2003

웹으로부터 유용한 정보를 얻기 위한 연구는 현재 많이 진행되고 있다. 본 논문에서는 특히 웹 로그 데이터의 희소성에 대한 문제 해결과 이를 통한 웹 사용자의 군집화 방안에 대하여 연구하였다. MCMC 방법의 베이지안 추론에 의한 결측치 대체 기법을 이용하여 웹 데이터의 희소성을 제거하였고, 주성분에 의한 산점도를 통하여 형상지도의 차원을 결정한 자기 조직화지도를 이용하여 웹 사용자의 군집화를 수행하였다. 제안 기법은 기존의 방법들에 비해 모형의 정확도와 빠른 학습 시간을 제공하여 주었다. KDD Cup 데이터를 이용한 실험을 통하여 제안 방법에 대한 문제 해결 절차 및 성능 평가를 객관적으로 확인하였다.

• 한국자기공명학회논문지
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• 제20권2호
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• pp.41-45
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• 2016

Chemical investigation of a marine-derived fungus, Penicillium sp. 108YD020, resulted in the discovery of six bile acid derivatives, glycocholic acid (1), glycocholic acid methyl ester (2), cholic acid (3), glycochenodeoxycholic acid (4), glycodeoxycholic acid methyl ester (5), and cholic acid methyl ester (6). The structures of six bile acid derivatives 1-6 were determined by the detailed analysis of 1D, 2D NMR and LC-MS data, along with chemical methods and literature data analysis.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3553-3558
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• 2013

The three dimensional-quantitative structure activity relationship (3D-QSAR) studies on chemical features of pyridine-2-amines in the external region of c-Met active site (ER chemical features of pyridine-2-amines) were conducted by docking, comparative molecular field analysis (CoMFA), and topomer CoMFA methods. The CoMFA model obtained the partial least-squares (PLS) statistical results, cross-validated correlation coefficient ($q^2$) of 0.703, non cross-validated correlation coefficient ($r^2$) of 0.947 with standard error of estimate (SEE) of 0.23 and the topomer CoMFA obtained $q^2$ of 0.803, $r^2$ of 0.940, and SEE of 0.24. Further, the test set was applied to validate predictive abilities of models, where the predictive $r^2$ ($r{^2}_{pred}$) for CoMFA and topomer CoMFA models were 0.746 and 0.608, respectively. Each contribution of ER chemical features of pyridine-2-amines to the inhibitory potency showed correlation coefficients, $r^2$ of 0.670 and 0.913 for two core parts, 3-(benzo[d]oxazol-2-yl)pyridine-2-amine and 3-(1-(2,6-dichloro-3-fluorophenyl)ethoxy) pyridine-2-amine, respectively, with corresponding experimental $pIC_{50}$.