• 한국진공학회지
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• 제3권2호
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• pp.173-178
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• 1994

박막성장을 위한 초고진공 응용시스템을 제작하고 이것의 특성을 사중극질량분석계로 측정하였 다. 초고진공 시스템을 박막성장에 활용하기 위해서는 챔버 뿐만 아니라 펌프, 이온게이지, 전자총 등도 베이킹이 요구되었다. 또한 이온게이지와 전자총은 적어도 박막성장 20분전에 탈가스를 하여야함을 알 았다. 이 시스템으로 달성된 진공도는 7x10-11 torr이었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제35회 하계학술대회 초록집
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• pp.195-195
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• 2008

• 한국진공학회지
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• 제6권4호
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• pp.298-307
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• 1997

CRT부품 탈가스(outgassing)를 온도를 변화 시켜가며 측정할 수 있고 시료의 열탈착 특성을 측정할 수 있는 TDS(Thermal Desorption Spectroscopy) 측정 장치를 설계 제작하였다. 제작된 시스템은 유효 배기속도를 조절할 수 있는 진공 장치와 시료의 온도조절 장치, 탈가스 측정 가치로 구성되어 있다. 제작된 시스템의 최저 도달 진공도는 $1{\times}10^{-7}$Pa 이하였고 가변 콘덕탄스(conductance)를 채택하여 유효 배기 속도를 조절 할 수 있도록 제작되었다. 가변 콘덕탄스 조절에 따른 시료위치에서의 유효 배기 속도 변화를 측정하였다. 텅스텐 히터와 온도조절기를 이용하여 시료의 온도는 600℃까지 ±1℃ 이내 오차로 조절 할 수 있었으며 온도 상승률도 조절할 수 있었다. 측정계기로 사용한 이온 진공계(ion gauge)와 사중극 질량분석기(quadrupole mass spectrometer)의 감도를 측정하여 정량적인 측정을 할 수 있도록 하였다. 제작된 시스템을 이용하여 CRT 공정에서의 부품별 온도별 측정 예와 공정분석에의 적용 예를 보였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.218.2-218.2
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• 2014

그래핀은 높은 전기 전도도와 열전도도, 기계적 강도를 가지고 있고 동시에 높은 전자이동도($200,000cm^2{\cdot}V{\cdot}^1{\cdot}s{\cdot}^1$) 특성을 갖는 물질로써 차세대 소재로 각광받고 있다. 하지만 그래핀을 소자에 응용하기 위해서는 전사공정과 lithography 공정 과정에서 발생되는 PMMA(Poly methyl methacrylate) residue를 완벽하게 제거해야 하는 문제점이 있다. 특히, lithography 공정 중 완벽하게 PMMA residue 가 제거되지 않고 잔류해 있을 경우에 소자의 life time, performance에 악영향을 준다는 보고가 있다. 이와같은 문제를 해결하기 위해 화학적 cleaning, 열처리를 통한 cleaning, 전류 인가에 의한 cleaning과 같은 방법들을 이용하여 그래핀의 PMMA residue를 제거하는 공정들이 보고되고 있지만, 화학적 cleaning 방법의 경우 chloroform 이라는 독성물질 사용으로 인해 산업적으로 응용이 어렵고, 열처리 방법은 전극 등의 금속이 $200^{\circ}C$ 이상의 높은 온도에서 장시간 노출될 경우 쉽게 손상을 입으며, 전류 인가에 의한 cleaning 방법은 국부적으로만 효과를 볼 수 있기 때문에 lithography 공정 후 PMMA residue를 효과적으로 제거하기에는 한계를 보이고 있다. 본 연구에서는 Ar을 이용하는 Ion beam 시스템을 통해 beam energy를 제어함으로써 PMMA residue를 효과적으로 제거하는 연구를 진행하였다. 최적화된 플라즈마 발생 조건을 찾기 위해 QMS(Quadrupole Mass Spectrometer)를 이용하여 입사하는 ion energy와 flux 양을 컨트롤 하였고, 250 W에서 최적화된 ion energy distribution 영역이 존재한다는 것을 확인할 수 있었다. 또한, 25 Gauss 정도의 electro-magnetic field를 이용하여 Ar의 ion energy를 10 eV 이하로 낮추어 damage를 최소화함으로써 효과적으로 그래핀을 cleaning 할 수 있었다. Cleaning과정에서 ion bombardment에 의해 발생한 damage는 $250^{\circ}C$에서 6시간 동안 annealing 공정을 거치면서 회복되는 것을 Raman spectroscopy의 D peak ($1335cm{\cdot}^1$) / G peak ($1572cm{\cdot}^1$) ratio 로 확인할 수 있었고, PMMA residue의 cleaning 여부는 G peak ($1580cm{\cdot}^1$)의 blue shift와 2D peak ($2670cm{\cdot}^1$)의 red shift를 통해 확인하였다. 그리고 AFM (Atomic Force Microscopy)을 이용하여 cleaning 공정과정에서 RMS roughness가 4.99 nm에서 2.01 nm로 감소하는 것을 관찰하였다. 마지막으로, PMMA residue의 cleaning 정도를 정량적으로 분석하기 위해 XPS (X-ray Photoelectron Spectroscopy)를 이용하여 sp2 C-C bonding이 74.96%에서 87.66%로 증가함을 확인을 할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제16권2호
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• pp.101-104
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• 1995

In an attempt to understand the nature of hyperthermal ion-surface collisions, noble gas ion beams (He+, Ne+, Ar+, and Xe+) are scattered from a Si(100) surface for collision energies of 20-300 eV and for 45°incidence angle. The scattered ions are mass-analyzed using a quadrupole mass spectrometer and their kinetic energy is measured in a time-of-flight mode. The scattering event for He+ and Ne+ can be approximated as a sequence of quasi-binary collisions with individual Si atoms for high collision energies (Ei > 100 eV), but it becomes of a many-body nature for lower energies, Ar+ and Xe+ ions undergo mutliple large impact parameter collisions with the surface atoms. The effective mass of a surface that these heavy ions experience during the collision increases drastically for low beam energies.

• 한국환경농학회지
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• 제34권3호
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• pp.230-237
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• 2015

BACKGROUND: To identify the sources of inaccuracy in LC/MS/MS methods used in the routine quantitation of small molecules are described and discussed. METHODS AND RESULTS: Various UPLC coupled to triple quadrupole mass spectrometer and time of flight (TOF) were used to identify the potential sources of inaccuracy and inducing the pitfalls of qualification and quntitation during the veterinary drug residue analysis. Some of stable isotope labelled veterinary drugs, which were used as internal standards, presented "cross-talk", regardless of manufactures of mass spectrometer and types of spectrometer. Group of sulfonamides also presented inaccuracy qualification and quantitation due to the multi-residue analytical method with the same fragment ions at the close retention times. CONCLUSION: The phenomena of "cross-talk" occurring between subsequently monitored transition from stable isotope labelled and isotope non-labelled authentic chemical were identified. To prevent errors and achieve more accurate data during the analysis of small molecules by LC/MS/MS SRM method, Followings should be taken care of and kept checking; purity and concentration of stable isotope as an internal standard, prevention of carry-over during the separation in column, minimizing the ion suppression by matrix effect, identification of retention time, precursor ion and product ion, and full knowledge of data processing including smoothing and peak integration.

• Natural Product Sciences
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• 제24권3호
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• pp.206-212
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• 2018

Xanthii Fructus has been traditionally used for the treatment of rhinitis, rheumatoid arthritis, and eczema. In this study, a high-performance liquid chromatography-photodiode array (HPLC-PDA) method was developed and then used for the simultaneous analysis of eight phenylpropanoids in Xanthii Fructus. The analytical column used for this separation was a $SunFire^{TM}$ $C_{18}$ column, maintained at $40^{\circ}C$. The mobile phase used was 1.0% acetic acid in distilled water and 1.0% acetic acid in acetonitrile with gradient elution. For identify of each component, the mass spectrometer (MS) was used a Waters triple quadrupole mass spectrometer requipped with electrospray ionization (ESI) source. The HPLC-PDA method showed good linearity: correlation coefficients were ${\geq}0.9996$. The limits of detection and quantification of the eight compounds were 0.02 - 0.04 and $0.06-0.14{\mu}g/mL$, respectively. The extraction recoveries ranged from 97.51 to 108.67%. The relative standard deviation values of intra- and inter-day precision were 0.06 - 1.55 and 0.09 - 1.68%, respectively. The validated HPLC-PDA method was applied to simultaneously analyse the amounts of eight phenlypropanoids in Xanthii Fructus.

• 한국대기환경학회지
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• 제34권1호
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• pp.120-143
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• 2018

The analytical methods and their ambient levels of organic nitrogenous compounds such as nitrosamines, nitramines (nitroamines), imines, amides and nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) in the atmosphere are summarized and discussed. Sampling for the analysis of organic nitrogenous compounds was mostly conducted using high volume air sampler. The direct liquid extraction (DLE) using sonification and the pressurized liquid extraction (PLE) using the accelerated solvent extraction (ASE) have been frequently employed for the extraction of organic nitrogenous compounds in the atmospheric samples. After extraction, clean-up via filtration and the solid phase extraction (SPE) and concentrations using nitrogen and rotary evaporator have been generally conducted but in some studies the clean-up and concentration steps have been omitted to prevent the loss of analyte and improve the recovery rate of the analytical procedure. Instrumental analysis was mainly carried out using gas chromatography (GC) or the high performance liquid chromatography (HPLC) coupled with the single quadrupole mass spectrometer or tandem mass spectrometer in the electron ionization (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI) mode and analysis sensitivity of nitrosamines and nitramines were higher in NCI mode. Desirable sampling and analysis methods for analyzing particulate organic nitrogenous compounds are suggested.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.187-190
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• 2004

In this study, PST thin films were etched with inductively coupled $Cl_2/(Cl_2+Ar)$ plasmas. The etch characteristics of PST thin films as a function of $Cl_2/(Cl_2+Ar)$ gasmixtures were analyzed by using quadrupole mass spectrometer (QMS). Systematic studies were carried out as a function of the etching parameters, including the RF power and the working pressure. The maximum PST film etch rate is 56.2 nm/min, because a small addition of $Cl_2$ to the $Cl_2/Ar$ mixture increased the chemical effect. It was proposed that sputter etching is the dominant etching mechanism while the contribution of chemical reaction is relatively low due to low volatility of etching products.

• Mass Spectrometry Letters
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• 제9권4호
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• pp.95-99
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• 2018

An innovative, simple, and rapid assay method based on liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed and validated for the simultaneous determination of eight statin drugs in human urine. A simple sample clean-up procedure using the "dilute and shoot" (DAS) approach enabled a fast and reliable analysis. The influence of the dilution factor was investigated to ensure detectability and reduce the matrix effect. Chromatographic separation was performed on a Phenomenex Kinetex C18 column ($50{\times}3.0mm$ i.d., $2.6{\mu}m$) using an elution gradient of mobile phase A composed of 0.1% acetic acid, and mobile phase B composed of acetonitrile, at a flow rate of 0.35 mL/min. Quantitation was performed on a triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using electrospray ionization in positive ion mode. The total chromatographic run time was 15 min. The method was validated for selectivity, sensitivity, recovery, linearity, accuracy, precision, and stability. The present method was successfully applied to the analysis of Rosuvastatin in urine samples after oral administration to healthy human subjects.