• 분석과학
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• 제15권5호
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• pp.410-416
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• 2002

본 연구에서는 LC - MS/MS를 이용해 혈장과 뇨중에서 반코마이신을 신속하게 정량분석하는 방법을 개발하였다. 크로마토그래피는 $C_{18}$ XTerra MS 컬럼 ($2.1{\times}30mm$, $3.5{\mu}m$)을 사용하여 분석하였다. 이동상으로는 0.25% 초산이 섞인 10% 아세토니트릴 용액을 사용하였으며, 유속은 $250{\mu}L/min$이다. 반코마이신과 카페인 (내부표준물질)은 multiple reaction monitoring (MRM) 방법을 사용하여 검출하였으며 반코마이신은 precursor ion m/z 725.0 ( $[M+2H]^{2+}$)와 product ion m/z 100.0을 사용하였다. 혈장에서 반코마이신의 검출한계는 1 nM이며 좋은 정확성과 정밀성을 보여주었다. 또한 혈장중에서 반코마이신의 정량범위는 $0.01{\mu}M$ - $100{\mu}M$이다. 혈장과 뇨중에서 반코마이신을 정량하는 이 분석방법은 약물동력학연구 및 관련연구에 성공적으로 적용되었다.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.349-358
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• 2000

Fabrication and Characterization of Bi$_{2}$/Sr$_{2}$/CaCu$_{2}$/O$_{8}$(Bi2212) superconductor thick films were fabricated successfully on C tapes by liquid reaction between Cu-free precursors of Bi$_{x}$/SrCaO/$_{y}$(x=1.2-2) and Cu tapes. Cu-free Bi-Sr-Ca-O powder mixtures were screen-printed on Cu tapes and heat-treated at 850-87$0^{\circ}C$ for several minutes in air oxygen nitrogen and low oxygen pressure. In order to obtain the optimum heat-treatment condition we studied the effect of the precursor composition the printing thickness and the heat-treatment atmosphere on the superconducting properties of Bi2212 films and the reaction mechanism. Microstructures and phases of thick films were analyzed by films and the reaction mechanism. Microstructures and phases of thick films were analyzed by optical microscope and XRD. The electric properties of superonducting films were examined by the four probe method. At heat-treatment temperature the thick films were in a partially molten state by liquid reaction between CuO of the oxidized copper tape and the precursors which were printed on Cu tapes. During the heat-treatment procedure Bi2212 superconducting particle nucleate and grow in preferred orientations.ons.s.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.132-132
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• 2003

Second-order nonlinear optical(NLO) materials have been extensively studied for applications in photonic devices, such as frequency doubling and electro-optical(EO) modulation, because of their large optical nonlinearity, excellent processibility, low dielectric constant, and high laser damage thresholds. The poling behaviour of NLO chromophore in organic/inorganic matrixes showed the randomization of poled NLO chromophore in the absence of poling Held. The liquid crystal molecules in a droplet showed a long-range orientational order along a director. Therefore, liquid crystal effects on poling behaviour of NLO chromophore dispersed in organically modified inorganic sol-gel materials were investigated. Using sol-gel process for the development of NLO material has received increasing attention, Organically modifked inorganic NLO sol-Eel materials are obtained via incorporation of the organic NLO active chromophore into an alkoxysilane based inorganic network. One of the most important thing in this works was that tetraethoxysilane(TEOS) and methyltrimathoxysilane(HTMS) were used as precursor followed by hydrolysis and condensation without using any acidic catalyst during the process. The NLO chromophores in the liquid crystal nanodomains were well mixed with I/O hybrid matrix, deposited on transparent ITO-coated glasses. The poling behaviour of liquid crystal effects of NLO chromophore dispersed in I/O hybrid matrix were investigated by UV-vis spectroscopy. Size distribution and morphology of the NLO chromophores doped in the liquid crystal nanodomains dispersed in I/O hybrid matrix were investigated by SEM.

• Progress in Superconductivity
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• 제11권1호
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• pp.42-46
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• 2009

With an aim of comparison, single grain Y-Ba-Cu-O (YBCO) bulk superconductors were fabricated using a liquid infiltration growth (LIG) process and a conventional melt growth (MTG) process with top seeding. The MTG process uses an $YBa_2Cu_3O_{7-x}$(Y123) powder as a precursor, while the LIG process uses $Y_2BaCuO_5(Y211)/Ba_3Cu_5O_8(Y035)$ pre-forms. The growth of a single Y123 domain on the top seed was successful in the both processes. Different feature between the two processes is the interior microstructure regarding the critical current density ($J_c$). The LIG-processed YBCO sample showed a lower porosity, more uniform distribution of Y211 particles and the enhanced Y211 refinement compared to the conventional MTG process. The $J_c$ improvement in the LIG process is attributed to the dispersion of finer Y211 particles as well as lower porosity within the Y123 superconducting matrix.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.328.2-328.2
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• 2014

Semiconductor nanowires (NWs) have attracted research interests due to the distinct physical properties that can lead to variousoptical and electrical applications. In this paper, we have grown InAs NWs viagold (Au)-assisted vapor-liquid-solid (VLS) and catalyst-free vapor-solid (VS) mechanisms and investigated on the p-type doping profile of the NWs. Metal-organic chemical vapor deposition (MOCVD) is used for the growth of the NWs. Trimethylindium (TMIn) and arsine (AsH3) were used for the precursor and diethyl zinc (DEZn) was used for the p-type doping source of the NWs. The effectiveness of p-type doping was confirmed by electrical measurement, showing an increase of the electron density with the DEZn flow. The structural properties of the InAs NWs were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, we characterize atomic distribution of InAs NWs using energy-dispersive X-ray spectroscopy (EDX) analysis.

• Mass Spectrometry Letters
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• 제11권1호
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• pp.10-14
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• 2020

Riboflavin is a water-soluble vitamin, which serves as a precursor to flavin mononucleotide and flavin adenine dinucleotide. This study aimed to develop a simple and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for the quantification of riboflavin in the Beagle dog plasma. This method utilized simple protein precipitation with acetonitrile and ¹³C₄, ¹⁵N₂-riboflavin was used as an internal standard (IS). For chromatographic separation, a hydrophilic interaction liquid chromatography (HILIC) column was used with gradient elution. The mobile phase consisted of 0.1% (v/v) aqueous formic acid with 10 mM ammonium formate and acetonitrile with 0.1% (v/v) formic acid. Since riboflavin is an endogenous compound, 4% bovine serum albumin in phosphate buffered saline was used as a surrogate matrix to prepare the calibration curve. The quantification limit for riboflavin in the Beagle dog plasma was 5 ng/mL. The method was fully validated for its specificity, sensitivity, accuracy and precision, recovery, and stability according to the US FDA guidance. The developed LC-MS/MS method may be useful for the in vivo pharmacokinetic studies of riboflavin.

• 대한기계학회논문집B
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• 제29권4호
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• pp.504-511
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• 2005

The generation of fine relics of inorganic and metallic materials from precursor suspensions is of significant current interest as it holds the key to the fabrication of display and printed circuit board. Some novel printing methods depositing ceramic particles have been suggested in recent years. When a conducting liquid is supplied to a capillary nozzle at a low flow rate and when the interface between air and the liquid is charged to a sufficiently high electrical potential, the liquid meniscus takes the form of a stable cone, whose apex emits a microscopic jet. This is called as a cone-jet mode. In our experiments, an alumina particles flowing through a nozzle were subjected to electro-hydrodynamic printing in the cone-jet mode. The pattern of 'YONSEI' characters was tested at $10 {\mu}l/min$ of alumina ink flow rate and different applied voltages. At an applied voltage of 6 kV, feature size was in the range of $250 {\mu}m.$

• 분석과학
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• 제36권1호
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• pp.53-58
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• 2023

2'-Hydroxy-3',4'-methylenedioxy-3,4,5-trimethoxychalcone (HMTC) is a newly synthesized chalcone that affects proliferation, cytotoxic potential and apoptosis in human leukemia cells. However, no validated determination method has been described so far for HMTC in biological samples. Thus, we developed a liquid chromatographic method using a tandem mass spectrometry to determine HMTC in rat plasma. Liquid-liquid extraction with ethyl acetate was used for the clean-up procedure. The analyte was separated on a reversedphase column with mobile phase of distilled water and acetonitrile (2:8, v/v, including 0.1 % formic acid). The ion transition of the precursor to the product ion was principally deprotonated ions [M-H]^- at m/z 356.8 → 327.2 for HMTC. This analytical method was successfully applied in pharmacokinetic study of HMTC after intravenous administration in rats.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.474-477
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• 2002

We performed a continuous heat treatment experiment for long Si$_2$Sr$_2$CaCuO$_{x}$ (Bi2212) superconductor tapes on copper substrates. A precursor that contains a mixture of Bi$_2$O$_3$, SrCO$_3$, and CaCO$_3$ powders was prepared and screen-printed on Cu tapes. The screen- printed tapes were thermally treated by consecutive processes with various temperature settings using an air-filled tube furnace. The diffraction patterns and the microstructures of the high temperature superconductor thick films were analyzed by X-ray diffractometry (XRD) and optical Microscopy respectively, and the critical temperatures of the superconducting thick films were measured. The critical temperatures of the superconducting films were measured to be about 77K, and the films'crystallographic c-axes were confirmed to be normal to the film surfaces by XRD and morphology observation. We also observed that the thick superconducting layer is formed and aligned on the copper substrate via partial melted state that consists of a liquid phase and a secondary phase.e.

• JSTS:Journal of Semiconductor Technology and Science
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• 제2권3호
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• pp.205-212
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• 2002

The growth characteristics of metal-organic chemical vapor deposition (MOCVD) $Pb(Zr_xTi_{1-x})O_3 (PZT) thin films were investigated for the application of high-density ferroelectric random access memories (FRAM) devices beyond 64Mbit density. The supply control of Pb precursor plays the most critical role in order to achieve a reliable process for PZT thin film deposition. We have monitored the changes in the microstructure and electrical properties of films on increasing the Pb precursor supply into the reaction chamber. Under optimized conditions, $Ir/IrO_2/PZT(100nm)/Ir capacitor shows well-saturated hysteresis loops with a remanent polarization (Pr) of $~28{\mu}C/textrm{cm}^2$ and coercive voltage of 0.8V at 2.5V. Other issues such as step coverage, compositional uniformity and low temperature deposition was discussed in viewpoint of actual device application.