• 한국환경성돌연변이발암원학회지
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• 제26권1호
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• pp.20-24
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• 2006

식용 달팽이 (Achatina fulica])의 추출물 RM 60을 사용하여 E. coli D31을 대상으로 순수한 항균성 물질을 분리 정제하였다. 정제한 항균성 물질은 MALDI-TOF Mass spectrometra를 사용하여 분자량을 측정한 결과, 1392.64 Da 단일 peak를 얻을 수 있었으며, 이 후 Edman 분해법을 이용한 peptide sequencer를 사용하여 일차구조 분석을 조사하고 있다.

• Biomolecules & Therapeutics
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• 제13권2호
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• pp.90-94
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• 2005

Prazosin hydrochloride is an antihypertensive drug with selective ${\alpha}_1$-adrenoreceptor blocking effects. A simple high performance liquid chromatographic method has been developed and validated for the quantitative determination of prazosin in human plasma. A reversed-phase C18 column was used for the separation of prazosin and terazosin (internal standard) with a mobile phase composed of water, acetonitrile and triethylamine(75:25:0.1, V/V;pH5.0) at a flow rate of 1.5 ml/min. the fluorescence detector was set at excitation and emissionwavelengths of 250 and 370 nm, respectively. Intra-and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification of 0.5 ng/ml. Good recovery (>80%) was seen in plasma. Prazosin was stable in human plasma under various storage conditions. This method was used successfully for a pharmacokinetic study in plasma after oral administration of a single 2-mg dose as prazosin base to 16 healthy volunteers. The maximum plasma concentration of prazosin was 23.1 ${\pm}$ 16.5 ng/ml at 2.1 h, and the mean area under the curve and elimination half-life were calculated to be 108.4 ${\pm}$ 74.2 ng ${\cdot}$hr/ml and 2.5 ${\pm}$ 0.6 h, respectively.

• International Journal of Precision Engineering and Manufacturing
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• 제2권3호
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• pp.41-46
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• 2001

This paper discusses the feasibility of improving micro-machining accuracy by using two-dimensional(2-D) vibration cutting. Vibration cutting is generated by two piezo actuators arranged orthogonally : one is actuated by a sine curve voltage input, and the other is actuated by a phase-shifted sine curve voltage. A tool attached to the vibrator oscillates in a 2-D elliptical motion, depending on the frequencies, amplitudes, and the phase shifts of two input signals and the workpiece feedrate. Along the elliptical tool locus, cutting is done in the lower part, and non-cutting is done in the upper part. By this way a unique feature of 2-D vibration cutting, that is, air lubrication between a tool and chips, is caused. Another unique feature of 2-D vibration cutting was experimentally verified, that is, some negative thrust force occurs as the direction of chip movement on a tool rake face is reversed. Those features not only help chips flow smoothly and continuously but also reduce cutting force, which results in a higher quality machined surface. Through tool path simulations and experiments under several micro-machining conditions, the 2-D vibration cutting, compared to conventional cutting, was found to result in a great decrease in the cutting force, a much smoother surface, and much less burr.

• 대한수의학회지
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• 제48권1호
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• pp.9-16
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• 2008

A method for the quantification of eugenol in the medicinal herb Clove was developed and validated. For preparation of sample solutions clove was dried at $60^{\circ}C$ for 2h and ground by mixer and extracted with 95% ethanol for shaking extraction. The elutes were analyzed by HPLC system included a reversed phase column, a isocratic mobile phase of 60% methanol and PDA detector set at 280 nm. Calibration graphs were linear with very good correlation coefficients ($r^2>0.9999$) from $0.0125~1{\mu}g/ml$. The limit of detection per sample injection ($20{\mu}l$) was $0.81ng/{\mu}l$ and limit of quantification was $2.47ng/{\mu}l$. The method showed good intra-day precision (%RSD 0.08 ~ 0.27%) and inter-day precision (%RSD 0.32 ~ 1.19%).

• 한국약용작물학회지
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• 제14권5호
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• pp.289-292
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• 2006

High performance liquid chromatography (HPLC) was used for the determination of lignans, eleutherosides B and E, in Acanthopanax sessiliflorus fruits and their fermented wine. The lignans were quantified by a reversed-phase system using a gradient of $H_2O$ and acetonitrile as a mobile phase within 20 min. The analysis was successfully carried out within 20 min. The contents of eleutherosides Band E as main active principles of Acanthopanax species were measured in A. sessiliflorus fruits (1.15 and $8.49\;{\mu}g/mg$, respectively), their fermented wine (0.45 and $1.33\;{\mu}g/mg$, respectively) and wine residues (no detection).

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.946-951
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• 2005

Biodegradation of the endocrine-disrupting chemical di-n-butyl phthalate (DBP) was investigated using a bacterium, Pseudomonas fluorescens B-1, isolated from mangrove sediment. The effects of temperature, pH, salinity, and oxygen availability on DBP degradation were studied. Degradation of DBP was monitored by solid-phase extraction using reversed-phase HPLC and UV detection. The major metabolites of DBP degradation were identified as mono-n-butyl phthalate and phthalic acid by gas chromatography-mass spectrometry (GC-MS) and a pathway of degradation was proposed. Degradation by P. fluorescens B-1 conformed to first-order kinetics. Degradation of DBP was also tested in seawater by inoculating P. fluorescens B-1, and complete degradation of an initial concentration of $100{\mu}g/l$ was achieved in 144 h. These results suggest that DBP is readily degraded by bacteria in natural environments.

• 분석과학
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• 제13권3호
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• pp.282-290
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• 2000

본 연구는 390nm 이하에서 자외선 흡수가 완벽한 폴리카보네이트(광학용)에 첨가된 각종 첨가제를 아세톤으로 추출하거나 용해-침전 방식으로 분리하여 분석하는 것이다. 분리된 첨가제를 정성적으로 분석하기 위해 자외선흡광광도계, FT-IR 및 HPLC로 분석하였다. 분리된 물질은 광안정제 및 산화방지제(1차 및 2차)등의 첨가제와 단량체 및 올리고머가 함유된 복잡한 혼합물로 추정할 수 있다. 분리된 첨가물을 Bondapak $C_{18}$ 칼럼, 메탄올 이동상, PDA (Photodiode Array) 검출기를 사용한 역상(reversed phase, RP) HPLC 분석을 통해 비스페놀 A, Irganox 1010, Cyasorb UV-5411 성분들을 확인할 수 있있다. 또한, 자외선 흡광도를 이용한 정량분석을 통해 폴리카보네이트에 광안정제인 Cyasorb UV-5411가 0.12중량% 함유된 것을 알 수 있었다.

• 한국응용과학기술학회지
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• 제30권4호
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• pp.664-671
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• 2013

역상 HPLC 에 의한 화장품에 사용하는 수용성 고분자인 Xanthan gum의 간편하고 정확한 정량분석 방법을 개발하였다. 분석조건은 $C_{18}$분리관과 ELSD 검출기를 사용하였으며, 25mM ammonium acetate/acetonitrile의 기울기 용리에 의해 분리 되었다. 이때 검량선의 상관계수(correlation coefficient) $r^2=0.9993$, 정량범위 $50.3{\sim}604.1{\mu}g/ml$, 검출한계 $12.0{\mu}g/ml$ 및 정확성이 우수하였다. 이 방법은 화장품 중 Xanthan gum를 정확하고 간편하게 정량분석 가능함을 보여 주었다.

• 대한기계학회논문집
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• 제16권4호
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• pp.753-764
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• 1992

본 연구에서는 저에가 곤란한 저출력시의 증기발생기 수위에 의한 강제정지를 감소시키기 위한 방법을 강구하기 위해 증기발생기에 대한 기존의 열수력학적 모델들 을 수정, 보완하여 증기발생기에 실제적으로 작용하는 모든 입력인자와 출력인자인 수 위와의 관계를 전달함수의 형태로 파학하였다. 즉, 수축/팽창 현상과 직접적인 관계 가 있는 강수관(downcomer)에서의 유체력(driving force)을 정확히 계산하기 위해 모 멘텀 쎌(momentum cell)이 수위에 따라 달라지게 하였으며 1차측으로 부터의 열전달을 자세히 계산하기 위해 비등시작점을 경계로 하여 단상(single-phase)영역과 이상(two -phase)영역에 대해 각기 다른 관계식을 사용하였다.

• 대한화학회지
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• 제34권4호
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• pp.345-351
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• 1990

역상 고성능 액체 크로마토그래피에 Cu (Ⅱ)-L-Proline 킬레이트를 이동상에 첨가하여 답실아미노산(DABS-AA)을 광학분리했다. DABS-아미노산에 관한 머무름거동을 이동상으로 아세토니트릴, 착물 및 완충용액의 농도와 pH에 따라 연구 검토했다. DABS-아미노산의 광학분리선택성은 이동상의 pH와 킬레이트의 농도가 증가하면 증가하나 유기용매의 농도에 따라 감소한다. 완충액의 농도에는 무관하다. DABS-아미노산과 구리 착물간의 리간드 교환반응의 입체효과에 따른 시스-트란스 생성으로 분리메카니즘을 설명할 수 있다.