• 분석과학
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• 제17권4호
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• pp.289-294
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• 2004

고성능 액체 크로마토그래피를 이용하여 고삼 중의 oxymatrine을 분석하였다. acetonitrile을 포함하는 완충용액과 $C_{18}$컬럼을 이용한 역상 크로마토그래피를 수행하였다. Oxymatrine의 분리는 215 nm에서 UV흡수가 관측되었다. 고삼 중의 oxymatrine의 추출은 다양한 용매와 다양한 추출방법을 사용한 결과, 마쇄한 고삼의 최적의 추출 효율은 $80^{\circ}C$에서 50% ethanol로 5시간 동안 환류가열 하였을 때 가장 높은 효율을 보였다. 대부분의 추출 방법은 복잡한 전처리를 필요로 하지만, 본 연구에서는 승화 추출법으로 복잡한 전처리를 제외시킨 추출법을 고안하였다. 승화 추출은 높은 진공 ($1{\times}10^{-3}$ torr) 과 높은 온도 ($200^{\circ}C$)에서 수행되었다. 승화 추출법을 사용한 추출 효율은 다른 추출 방법들과 비교해서 전처리 과정을 거치지 않은 장점은 있었으나 추출 효율이 좀 낮았다.

• 동력기계공학회지
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• 제15권4호
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• pp.5-10
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• 2011

In case of using rapid vacuum-freeze drying for high quality dry flower of flowering plant, the morphological and physiological characteristics of dry rose showed as the following. The dry ratio of about 82% presented after 1 day in case of using rapid vacuum-freeze drying and it was reached that the optimum storage water content of general dry products was 18%. The dry ratio of about 89% presented after 4 days. This result indicates very short dry time comparing with natural dry time of 12 days. Also, the morphological characteristics of flowering plant in case of vacuum-freeze drying showed similar shape with real flower. The contraction decreased about 9% comparing with real flower under dry time of 72 hours. But the contraction in case of natural dry decreased 36% and showed noticeable difference. The brightness which affects physiological characteristics of dry flowering plant showed lower values according to the dry process and chromaticity was thick. After 4 days, natural dry was thick with about 2 times comparing with vacuum-freeze drying. In case of vacuum-freeze drying, the quantity of anthocyanin and chlorophyl which affect discoloration and bleaching of dry flowering plant showed the clear difference comparing with natural dry method due to the sublimation by vacuum after rapid freeze with short initial time.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.91-94
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• 1997

$\alpha$-sexithienyl($\alpha$-6T) thin films were deposited by Organic Molecular Beam Deposition(OMBD) technique, where the $\alpha$-6T was synthesized and purified by the sublimation method. The thin films of the $\alpha$-6T were deposited under various deposition conditions. The effects of deposition rate, substrate temperature. and vacuum pressure an the formation of these films have been studied. The molecular orientations of $\alpha$-6T films were investigated with the polarized electronic absorption spectroscopy. The molecules in the $\alpha$-6T film deposited at a low deposition rate under a high vacuum were aligned almost perpendicular to the substrate. The film deposited at an elevated substrate temperature (~9 $O^{\circ}C$) showed higher conductivity than the film deposited at room temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.187-190
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• 1996

Conducting polymers have band structures similar to those of inorganic semiconductors such as silicon. Several electronic devices have been constructed with conjugated polymers, mainly Schottky diodes and Metal-Insulator-Semiconductor Field-Effect Transistors (MISFET's). Organic semiconductor has been reported as active materials in MISFET's.$^{1.4}$ In our laboratory, $\alpha$-Sexithiencyl ($\alpha$-6T) has been synthesized and purified by sublimation method. In this study, thin films of $\alpha$-Sexithienyl were prepared on various substrates in ultra-high vacuum chamber by vacuum evaporation method, so called OMBD(Organic Molocular Beam Deposition).$^{7.9}$ The $\alpha$-Sexithienyl thin films were deposited with various deposition conditions. The crystalline structure, and molecular orientation of these films have being studied by using UV/Vis. spectroscopy and X-Ray Diffractometry.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1391-1392
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• 1997

The thin films of $\alpha$-Sexithiophene($\alpha$-6T) were deposited by Organic Molecular Beam Deposition(OMBD) technique. The $\alpha$-6T was synthesized and Purified by the sublimation method The thin films of the $\alpha$-6T were deposited under various deposition conditions. The effects of deposition rate substrate temperature, and vacuum pressure on the formation of these films have been studied. The molecular orientations of $\alpha$-6T films were investigated with the polarized electronic absorption spectroscopy. The molecules in the $\alpha$-6T film deposited at a low deposition rate under a high vacuum were almost aligned Perpendicular to the substrate. The film deposited at an elevated substrate temperature(${\sim}90^{\circ}C$) showed higher conductivity than deposited at room temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.518-520
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• 1997

Recently, thiophene oligomer with short chain lengths has received much attention as model compounds for facilitating better understanding of electronic and optical properties of polymers, because oligomer is well-defined chemical systems and its conjugation chain length can be exactly controlled. Moreover, organic this films based on conjugated thiophene oligomer have potential for application to electronic and optoelectronic devices such as MISFETs(metal-insulator-semiconductor field-effect transistors) and LEDs(light-emitting diodes). However, there is little knowledge on electronic and structural properties of linear-conjugated oligothiophenes in solid states, compared with those in solutions. $\alpha$-sexithienyl($\alpha$-6T) thin-films were deposited by OMBD(Organic Molecular Beam Deposition) technique, where the $\alpha$-6T was synthesized and purified by the sublimation method. The $\alpha$-6T films were deposited under various conditions. The effects of deposition rate, substrate temperature, and vacuum pressure on the formation of these films have been studied. The molecules in the $\alpha$-6T film deposited at a low deposition rate under a high vacuum were aligned almost perpendicular to the substrate. The $\alpha$-6T films deposited at an elevated substrate temperature showed higher conductivity than the film deposited at room temperature. Electrical characterization of these films will be also executed by using four-point probe measurement technique.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2895-2898
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• 2009

The complete structural characterization of dehydrodivanillin, an important natural product of interest to the food, cosmetics and aroma industries, has been carried out using multi-dimensional NMR spectroscopic techniques, and its previously $reported^{13}$C-NMR values have been reassigned. Dense and granular thin films of dehydrodivanillin have been grown by sublimation under high vacuum and studied using Scanning Electron Microscopy (SEM), electrical and optical techniques. The transmittance spectra of the films indicate a wide optical band gap of more than 3 eV. Typical J-V characteristics of Glass/ITO/dehydrodivanillin/Al structure exhibited moderate current densities ${\sim}10^{-4}\;A/cm^2$ at voltages > 25 V with an appreciable SCLC mobility of the order of $10^{-6}\;cm^2$/V-s.

• Food Science and Biotechnology
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• 제14권3호
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• pp.428-432
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• 2005

To compare volatile compounds in bulgogi cooked by different heating procedures, bulgogi was prepared by convection oven, electric pan and charcoal grill. A total of 61 volatile compounds, consisting of 4 pyrazines, 10 sulfur-containing compounds, 7 carbonyls, 7 alcohols, 7 aliphatic hydrocarbons, 25 terpene hydrocarbons, and 1 miscellaneous compound, were tentatively identified in bulgogi cooked by the three heating methods. Comparatively, the difference in volatile compounds identified in bulgogi using the three different heating methods was not significant, except for sulfur-containing compounds and carbonyls which were detected at higher levels in the bulgogi cooked by convection oven than in that cooked by the other two heating methods. On the other hand, some compounds, such as furfural, benzaldehyde, and (E,E)-2,4-decadienal, were detected only in the bulgogi cooked by charcoal.

• 한국진공학회지
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• 제7권4호
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• pp.361-367
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• 1998

유기 박막 트렌지스터의 활성층으로 사용하기 위하여 공액성 소중합체인 $\alpha$ -sexithiophene($\alpha$-6T)이라는 시료를 가지고 유기 분자선 증착법(OMBD)을 이용하여 박막 을 제작하였으며 $\alpha$-6T박막의 성막 조건에 따른 박막의 분자 배향, 결정구조 그리고 표면 특성을 알아보기 위해 angle-resolved UV/visible absorption spectroscopy, X-ray diffractometry(XRD) 그리고 atomic force microscopy(AFM)를 이용하였으며 그 분석 결과 성막 조건에 관계없이 모두 monoclinic한 결정구조를 갖으나, 초고진공, 낮은 성막 속도, 기 판의 온도가 높은 조건일 경우 $\alpha$-6T 분자들이 기판에 수직적으로 배열한다는 것을 확일할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.158-158
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• 2009

This paper focuses on improving organic thin film transistor (OTFT) characteristics by controlling the self-organization of pentacene molecules with an alignable high-dielectric-constant film. The process, based on the growth of pentacene film through high-vacuum sublimation, is a method of self-organization using ion-beam (IB) bombardment of the $HfO_2/Al_2O_3$ surface used as the gate dielectric layer. X-ray photoelectron spectroscopy indicates that the IB raises the rate of the structural anisotropy of the $HfO_2/Al_2O_3$film, and X-ray diffraction patterns show the possibility of increasing the anisotropy to create the self-organization of pentacene molecules in the first polarized monolayer. An effective mobility of $2.3{\times}10^{-3}cm^2V^{-1}s^{-1}$ was achieved, which is significantly different from that of pentacene films that are not aligned. The proposed OTFT devices with an ultrathin $HfO_2$ structure as the gate dielectric layer were operated at a gate voltage lower than 5 V.