• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.177-182
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• 2012

A new composition of standardized Scutellariae Radix extract (HPO12) was developed for treatment of Alzheimer's disease. For the preclinical pharmacokinetic study of HPO12, a rapid, sensitive, and selective LCMS/MS method was developed and validated for the simultaneous determination of 4 bioactive compounds, baicalein, baicalin, wogonin, and wogonoside. After extraction with ethylacetate, chromatographic analysis was performed on a Thermo $C_{18}$ column ($150mm{\times}2.1mm$, $3{\mu}m$) with a mobile phase consisting of 0.1% formic acid (A) and 0.1% formic acid in 95% acetonitrile (B) by using gradient elution at a flow rate of $250{\mu}L/min$. Analytes introduced to a mass spectrometer were monitored by multiple reaction monitoring (MRM) in positive ion mode. Using $25{\mu}L$ of plasma sample, the method was validated over the following concentration ranges: 25-5000 ng/mL for baicalein, 20-40000 ng/mL for baicalin, 1-1000 ng/mL for wogonin, and 5-10000 ng/mL for wogonoside. The intra- and inter-day precision and accuracy of the quality control samples at the 4 concentrations showed $\leq$ 13.7% relative standard deviation (RSD) and 86.6-105.5% accuracy. The method was successfully applied to determine the concentrations of baicalein, baicalin, wogonin, and wogonoside in rat plasma after intraperitoneal and oral administrations of HPO12.

• Journal of Ginseng Research
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• 제40권3호
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• pp.220-228
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• 2016

Background: Among the various ginseng strains, Shizhu ginseng is endemic to China, mainly distributed in Kuandian Manchu Autonomous County (Liaoning Province, China); however, not much is known about the compounds (especially saponins) in Shizhu ginseng. Methods: A rapid, sensitive, and reliable ultra-high performance liquid chromatography coupled with MS/MS (UHPLC-MS/MS) method was developed to separate and identify saponins in Shizhu ginseng. Results: The separation was carried out on a Waters ACQUITY UPLC BEH $C_{18}$ column ($100mm{\times}2.1mm$, $1.7{\mu}m$) with acetonitrile and 0.1% formic acid aqueous solution as the mobile phase under a gradient elution at $40^{\circ}C$. The detection was performed on a Micromass Quattro Micro API mass spectrometer equipped with electrospray ionization source in both positive and negative modes. Under the optimized conditions, a total of 31 saponins were identified or tentatively characterized by comparing retention time and MS data with related literatures and reference substances. Conclusion: The developed UHPLC-MS/MS method was suitable for identifying and characterizing the chemical constituents in Shizhu ginseng, which provided a helpful chemical basis for further research on Shizhu ginseng.

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.1043-1047
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• 2008

Simultaneous determination of amitraz, bromopropylate, coumaphos, cymiazole and 2,4-dimethylaniline in 200 honey samples purchased in Korea was performed by reversed-phase high-performance liquid chromatography with multiple UV detection. 2% Acetone in hexane was used for a liquid-liquid extraction and 20-40% water in acetonitrile solutions were used as mobile phases. The LOD for the analytes varied between 0.4 and 1.5 $\mu$g/L and the recoveries were yielded between 64 and 94%. Relative standard deviation of the repeatability of the method is less than 15%. Amitraz was not present in amount above 10 $\mu$ g/L and one for coumaphos and cymiazole and two for bromopropylate, and three for 2,4-dimethylanilne were detected in amount above 10 $\mu$ g/ L. Levels of the acaricide residues found were less than 50 $\mu$ g/L.

• 한국식품과학회지
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• 제28권3호
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• pp.600-603
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• 1996

두릅나무(Aralia elata $S_{EEMANN}$) 껍질의 MeOH추출물이 세균과 호모, 곰팡이 등에 대한 항미생물 활성을 보여 solvent fractionation, Silica gel adsorption chromatography, Sephadex LH-20 column chromatography, silica gel partition chromatography, HPLC 등의 기법으로 활성물질을 순차 정제하여 얻어진 활성물질을 1% acetic acid-MeOH (60 : 40, v/v)용매계의 HPLC에 의해 분리하였다. 분리된 성분($t_r$ 17.1 min)의 활성본체를 구명하기 위하여 $MS,\;^1H-NMR\;and\;^13C-NMR$. 등을 이용하여 기기분석한 결과, trans-3,4-dihydroxycinnamic acid로 동정되었다. 3,4-dihydroxycinnamic acid가 두릅에서 항미생물 활성물질로서 분리, 동정된 것은 처음으로 생각된다.

• Food Science and Biotechnology
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• 제15권1호
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• pp.24-27
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• 2006

A simple HPLC quantification method was developed for genistein, genistin, daidzein, and daidzin in soybeans and soybean products. The procedure used a $4.6{\times}100\;mm$ $Chromolith^{(R)}$ RP-18e column with a mobile phase of 1% HOAc in 20% MeOH to 1% HOAc in 80% MeOH for 10 min. The injection volume was $2\;{\mu}L$ at a flow rate of 2 mL/min. Detection was carried out under UV at 254 nm. Under these conditions, the major isoflavones daidzein, daidzin, genistein, and genistin in soybean and soybean pastes were eluted within 7 min with baseline separation. Optimal extraction of the above four major isoflavones was achieved when 40 g of soybean or soybean paste was refluxed in 100 mL of 95% ethanol for 2 hr. Ten different soybean cultivars and nine commercial soybean pastes were analyzed by this method. The total isoflavone content was highest in the cultivar Somyung ($2,497\;{\mu}g/g$ dry weight). The isoflavone content in soybean pastes varied widely from manufacturer to manufacturer (an almost five-fold difference between the highest and lowest values). Such variations were presumably due to differences in fermentation conditions, type of soybeans used, and levels of such additives as starch and salt.

• 전자공학회논문지
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• 제52권6호
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• pp.50-56
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• 2015

본 논문에서는 모바일 응용에 적합한 고효율의 빠른 응답 특성을 가지는 히스테리틱 벅 변환기를 제안한다. 기존 히스테리틱 변환기의 문제점인 큰 출력 전압 리플과 작은 용량의 전력 인덕터 사용의 어려움을 삼각파 신호 발생기를 통해 해결하였다. 그리고 부하 전류에 따라 가변하는 스위칭 주파수를 PLL(Phase Locked Loop)구조를 사용하여 일정하게 함으로써 주변 IC에 미치는 EMI(Electro Magnetic Interference)잡음을 최소화 하였다. 이 회로는 BCDMOS 0.35um 2-poly 4-metal 공정으로 제작되었으며, 측정 결과 입력전압 3.7V, 출력전압 1.2V 부하 전류 50~500mA 범위에서 20mV 이하의 출력 전압 리플을 나타내며 170mA 이상의 부하 전류를 구동하는 경우 2MHz의 고정된 스위칭 주파수에서 동작하였다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3727-3734
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• 2012

An analytical method has been developed for the rapid determination of perfluorinated compounds (PFCs) in human serum samples. The extraction and purification of PFCs from human serum were performed by the modified method of previous report. Ten PFCs were rapidly separated within 3.3 min by C18-monolithic column liquid chromatography (LC) and detected by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) in negative ion mode. The runtime of PFCs on monolithic column LC was up to 4-fold faster than that on conventional column LC. The effect of triethylamine (TEA) to the mobile phase has investigated on the overall MS detection sensitivity of PFCs in ESI ionization. Quantification was performed by LC-MS/MS in multiple-ion reaction monitoring (MRM) mode, using $^{13}C$-labeled internal standards. Method validation was performed to determine recovery, linearity, precision, and limits of quantification, followed by, the analysis of a standard reference material (SRM 1957 from NIST). The overall recoveries ranged between 81.5 and 106.3% with RSDs of 3.4 to 16.2% for the entire procedure. The calibration range extended from 0.33 to 50 $ng\;mL^{-1}$, with a correlation coefficient ($R^2$) greater than 0.995 and the limits of quantification with 0.08 to 0.46 $ng\;mL^{-1}$. This approach can be used for rapid and sensitive quantitative analysis of 10 PFCs in human serum with high performance and accuracy.

• 대한본초학회지
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• 제32권1호
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• pp.55-62
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• 2017

Objectives : Crataegi Fructus has been used as traditional medicines for more digestion action, amenorrhea due to blood stasis, and hyperlipemia. The aim of this study was to compare of Crataegi Fructus in South Korea collected during three years according to the standards in monographs of the Korean Pharmacopoeia Eleventh edition (KP 11). Methods : Crataegi Fructus was carried out identification test (Qualitative reaction, Thin layer chromatography), heavy metal test, and total ash registered at KP. Add to we tested loss on dry, contents of ethanol-soluble extracts, and HPLC profiling. Results : Identification test (TLC) was on comparing with ursolic acid standard solution in $R_f$ value, all samples showed red purple spot ($R_f$ value 0.9). Ursolic acid spot in $R_f$ value 0.35 showed by changing mobile phase condition. Heavy metals showed contents for Pb, Cd, As, and Hg range of 0.0 ~ 0.5 ppm, 0.0 ~ 0.2 ppm, 0.0 ~ 0.3 ppm, and 0.0 ~ 0.1 ppm. Loss on drying was ranged from 5.5 to 11.9 %, total ash was between the range 2.7 ~ 4.0 %. Contents of ethanol-soluble extracts was ranged from 17.8 to 44.9 %. The content of chlorogenic acid was ranged from 0.0 to 0.1 % based on the chlorogenic acid standard curve. Conclusion : We have verified the current specification standard of Crataegi Fructus and standard that is not set. We hope that it will help the standardization of Crataegi Fructus.

• 전력전자학회논문지
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• 제15권6호
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• pp.498-505
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• 2010

In-Wheel System은 고성능의 전기모터를 Wheel에 직접 장착하여 파워트레인 요소를 모두 제거함으로써 차량시스템의 효율을 높인 시스템이다. 추후 친환경 차량에 적용할 수 있는 신개념의 플랫폼을 제공할 수 있는 고효율, 고성능 차량 시스템이기에 다양한 분야에 적용되고 있다. 이러한 시스템의 급증은 우리 생활의 안전과 직결되므로 개발단계에서 부품의 신뢰성을 확인하고 인증하여야 한다. 신뢰성이란 "부품이나 시스템이 주어진 환경에서 고장 없이 일정기간 동안 요구기능을 수행하는 특성"이다. 따라서 본 논문에서는 In-Wheel System의 핵심 부품인 In-Wheel Motor를 신뢰성 평가 중 하나인 내구 수명에 대한 검증 방안을 In-Wheel Motor의 운전 조건으로부터 가감속 토크 및 실효토크를 계산해서 이를 바탕으로 가속수명시험을 위한 속도 패턴을 제안하여 시험시간을 단축하고, 또한 In-Wheel Motor의 수명 신뢰성을 검증한다.

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.660-664
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• 2008

본 연구에서는 분석용 HPLC를 사용하여 단삼(Salvia Miltiorrhiza Bunge; SMB)의 추출물로부터 Tanshinone IIA (TIIA)를 분리하였다. 우선 유기용매를 사용하여 추출 및 전처리한 단삼 추출액으로부터 HPLC를 사용하여 TIIA을 분석하였으며, 고순도의 TIIA을 분리하기 위한 최적의 분석조건을 실험적으로 구하였다. 모든 단삼 시료들은 메탄올, 에틸아세테이트, 에탄올 등과 같은 유기용매로 추출하고 비교 분석하였다. 실험결과에 의하면 추출용매로 메탄올을 사용한 경우, 단삼으로부터 TIIA의 추출효율이 가장 우수 하였다. 또한 TIIA를 분석하기 위한 조건으로는 $C_{18}$ 컬럼을 사용 하였고, 이동상은 물과 메탄올을 사용하여 주로 등용매 용리를 적용하였을 때, SMB 1 mg에 $2.154{\mu}g$ TIIA를 분말로 추출하였다.