• KSBB Journal
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• 제18권3호
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• pp.202-206
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• 2003

역미셀과 가압이산화탄소를 이용한 난백 lysozyme의 추출실험에서 일정한 압력의 이산화탄소를 유기용액에 가하였을 때 lysozyme의 추출율과 그 때 형성되는 역미셀의 크기, 즉 역미 셀 내부의 수분함량 ($W_{0}$)를 알아보았다. 이산화탄소로 가압된 상태에서도 수용액에서 유기용액으로의 lysozyme의 추출 경향은 실험조건인 수용액의 이온강도, pH, 유기용액의 계면활성제의 농도를 달리 하였을 때 기존의 다른 연구와 유사한 경향을 나타내었으며, 이산화탄소의 압력을 102 bar까지 증가시켰을 때 가장 높은 추출율을 나타내었다. 또한 이때 역미셀 내부의 수분함량 ($W_{0}$)을 측정한 결과, lysozyme의 추출율과 역미셀 내부의 수분함량은 비례함을 확인할 수 있었다.

• 한국재료학회지
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• 제25권1호
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• pp.9-15
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• 2015

The effect of retained and reversed austenite on the damping capacity in high manganese stainless steel with two phases of martensite and austenite was studied. The two phase structure of martensite and retained austenite was obtained by deformation for various degrees of deformation, and a two phase structure of martensite and reverse austenite was obtained by reverse annealing treatment for various temperatures after 70 % cold rolling. With the increase in the degree of deformation, the retained austenite and damping capacity rapidly decreased, with an increase in the reverse annealing temperature, the reversed austenite and damping capacity rapidly increased. With the volume fraction of the retained and reverse austenite, the damping capacity increased rapidly. At same volume of retained and reversed austenite, the damping capacity of the reversed austenite was higher than the retained austenite. Thus, the damping capacity was affected greatly by the reversed austenite.

• 생명과학회지
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• 제19권12호
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• pp.1698-1704
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• 2009

Gemcitabine은 다양한 고형암 치료에 사용되는 항암제이다. 혈장내에서 cytidine deaminase에 의해 빠르게 대사되며, 친수성 성질로 인해 역상 액체크로마토그라피(reversed-phase liquid chromatography)를 이용한 농도 분석이 어렵다. 본 연구에서는 역상칼럼(reversed-phase column)을 이용한 초고속 액체크로마토그라피(ultra-performance liquid chromatography, UPLC) 방법에 의해 빠르고 정확한 속력(velocity)과 최고효능(peak efficiency)를 갖춘 분석법을 개발하고자 하였다. Gemcitabine과 2'-deoxycytidine의 머무름 시간(retension time)은 293 nm에서 각각 3.2분과 2.1분이었다. 검량선의 직선성 검정은 $0.1{\sim}20{\mu}g/ml$의 농도범위에서 높은 직선성을 나타내었다($r^2$>0.999). 일내(intra-day) 변이게수(coefficients of variation)와 일간(inter-day) 변이게수는 모두 10% 이하였다. 정확성(accuracy) 검정을 위한 일내 및 일간 평균농도 측정치가 97.3~113.5% 범위로 나타났다. 이러한 결과를 토대로, gemcitabine 농도를 측정하기 위한 새로운 분석법으로 빠르고 정확한 역상 UPLC 방법을 제안하고자 한다.

• 분석과학
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• 제22권2호
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• pp.148-151
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• 2009

역상 액체 크로마토그래피에서 다당유도체 선택자가 공유결합된 키랄 컬럼인 Chiralpak IB을 사용하여 N-FMOC $\alpha$-amino acid의 광학 이성질체의 분리를 수행하였다. 공유결합된 키랄 컬럼인 Chiralpak IB에서 여러 역상 이동상 조건들이 광학분할의 선택성과 분리인자, 머무름시간에 미치는 영향을 보여주었다. 또한 역상 액체 크로마토그래피에서 N-FMOC $\alpha$-amino acid의 광학 이성질체의 분리 결과를 순상 액체 크로마토그래피 결과와 비교하였는데 순상이동상을 사용한 것보다는 대체적으로 낮은 광학분할을 보여주었다.

• 동력기계공학회지
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• 제19권1호
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• pp.70-75
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• 2015

The influence of reversed austenite on the damping capacity in austenitic stainless steel with two phase of martensite and reversed austenite was investigated. The two phases of deformation induced martensite and reversed austenite was obtained by an reverse annealing treatment at $500^{\circ}C{\sim}700^{\circ}C$ for various time after 70% cold rolling. With an increase of the reverse annealing treatment temperature and time, volume fraction of reversed austenite was rapidly increased. With an increase of volume fraction of reveresd austenite, damping capacity was rapidly increased. At same volume of reveresd austenite, damping capacity of reversed austenite obtained by reverse annealing treatment at $700^{\circ}C$ for various time was higher then reveresd austenite obtained by reverse annealing treatment at $500^{\circ}C{\sim}700^{\circ}C$ for 10min. Thus, the damping capacity was affected greatly by reversed austenite obtained by annealing treatment at $700^{\circ}C$ for various time.

• Bulletin of the Korean Chemical Society
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• 제13권3호
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• pp.280-285
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• 1992

Enantiomeric separation of free amino acids has been achieved by a reversed phase liquid chromatography with addition of a Cu(Ⅱ) complex of N-alkyl-L-proline (alkyl: propyl, pentyl or octyl) to the mobile phase. The amino acids eluted were detected by a postcolumn OPA system. N-alkyl-L-proline was prepared and used as a chiral ligand of Cu(Ⅱ) chelate for the enantiomeric separation. The concentration of the Cu(Ⅱ) chelate, the organic modifier and pH affect the enantiomeric separation of free amino acids. The retention behaviour, varied with change in pH and the concentration of the Cu(Ⅱ) chelate, was different compared with those of the derivatized amino acids. The elution orders between D- and L-forms were consistent except histidine showing that L-forms elute earlier than D-forms. The retention mechanism for the enantiomeric separation can be illustrated by the stereospecificity of the ligand exchange reaction and the hydrophobic interaction between the substituent of amino acids and reversed phase, $C_18$.

• 동력기계공학회지
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• 제17권2호
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• pp.114-120
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• 2013

This study was carried out to investigate the relationship between mechanical properties and damping capacity in high manganese austenitic stainless steel with two phase mixed structure of reversed austenite and deformation induced martensite. Reversed austenite of ultra-fine grain size less than $0.3{\mu}m$ was obtained by reversion treatment. Two phase structure of deformation induced martensite and reversed austenite was obtained by annealing treatment at range of $500^{\circ}C{\sim}700^{\circ}C$ for various time in cold rolled high manganese austenite stainless steel. In stainless steel with two phase mixed structure of martensite and austenite, damping capacity decreased rapidly with the increasing hardness and strength. With the increasing elongation, damping capacity was increased rapidly and then, slowly increased.

• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.3971-3976
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• 2012

A simple method was developed for the analysis of seven stilbene-type fluorescent whitening agents (FWAs) in paper materials by ion-pair reversed-phase high-performance liquid chromatography with fluorescence detection. These stilbene-type FWAs included two disulfonate, two tetrasulfonate, and three hexasulfonate compounds. After optimization of chromatographic conditions, the FWAs were satisfactorily separated using a reversed-phase column (RP-18) with the following isocratic mobile phase: methanol-water (60:40) containing 17.5 mM TBABr and 10 mM citrate buffer (pH = 7.0). The calibration plot was linear in the range from 5 to 500 ng/mL for two disulfo-FWAs and from 1 to 500 ng/mL for the other five FWAs. Precision levels of the calibration curve as indicated by RSD of response factors were 1.2 and 8.1%. Limits of quantitation (LOQ) ranged from 1.2 to 11 ng/mL.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.569-574
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• 2005

A coupled column liquid chromatography system was applied for the separation of the burnup monitors in spent nuclear fuel sample solutions. A reversed phase column was studied for the adsorption behavior of uranyl ions using alpha-hydroxyisobutyric acid as an eluent and used for the separation of plutonium and uranium. A cation exchange column prepared by coating 1-eicosylsulfate onto the reversed phase column was used for the separation of the lanthanides. In addition, retention of Np was checked with the reversed phase column and cation exchange column, respectively, according to the oxidation states to observe the interference effect for the separation of burnup monitors. This chromatography system showed a great reduction in separation time compared to a conventional anion exchange method. A good agreement from the burnup data was obtained between for this method and a conventional anion exchange method to within 1% of a difference for the spent nuclear fuel samples of about 40 GWD/MTU.

• KSBB Journal
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• 제5권4호
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• pp.411-414
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• 1990

The extraction behavior of an alkaline protease using reversed micelles was investgated. The reversed micellar solution consisted of AOT in isooctane. It was found that distribution of arkaline protease into the organic phase increased at lower pH, lower ionic strength, and higher AOT concentration. When the real fermentation broth was extracted of alkaline protease, an activity yield of 20% and a purification factor of 2.0 were obtained.