• Journal of the Korean Vacuum Society
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• v.2 no.1
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• pp.9-16
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• 1993

부분압 분석 장비의 감도 측정 시스템을 설계 제작하였다. 이 시스템을 이용하여 부분압측정기기로 많이 쓰이는 Quadrupole Mass Spectrometer의 N2, O2, Ar, CO, H2에 대한 감도를 10-4∼10-8torr 영역에서 측정하여 감도의 압력 의존성을 보고 검출 방식, Emission current, Secondary Electron Multiplier 전압 등이 감도에 미치는 영향도 측정하였다. 실험 결과 기체 종류에 따라서는 물론 사용조건에 따라서도 감도의 절대값 변화 및 압력 의존성 변화가 아주 심한 것을 알 수 있었다. 따라서 Quadrupole Mass Spectrometer를 정량적인 측정에 이용하기 위해서는 이에 대한 감도 측정 및 특정조사가 반드시 선행되어야 한다.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.314-318
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• 1993

Quadrupole mass spectrometer는 부분압 측정 및 잔류기체 분석에 널리 이용되고 있는 장비이다. CO, H2, Ar이 혼합되어 존재할 때 quadrupole mass spectrometer의 감도를 10-4∼10-8torr영역에서 측정하고 단일기체로 존재할 때의 감도와 비교하였다. 그 결과 일정한 부분압을 유지하고 있는 경우라도, 주위 분위기 기체 종류와 부위기 기체 압력에 따라 감도 별화가 심한 것을 알 수 있었다. 따라서 QMS를 부분압 측정이나 조성분석에 이용하기 위해서는 이에 대한 특성조사가 반드시 필요하다.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.241-246
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• 1989

Continuous on-line monitoring of cell concentration and growth rate in aerobic batch fermentation process was carried out by analyzing the exhaust gas composition of tormentor with a quadrupole mass spectrometer. From the mass spectrometric analyses of major gaseous components, i.e. $N_2$, $O_2$, $CO_2$ and $H_2O$, and the material balance equations for oxygen and carbon dioxide, oxygen uptake rate (OUR) rind carbon dioxide evolution rate (CER) were instantaneously calculated using a computer (16-bit IBM PC-AT) interfaced to a quadrupole mass spectrometer. The calculated OUR and CER data were used for the estimation of cell concentration and growth rate of Candida utilis during batch culture. It was found that the cell concentration could be satisfactorily estimated from the data of OUR arid CER during the culture and this method could be successfully und for the continuous monitoring of cell growth and growth rate.

• Journal of the Korean institute of surface engineering
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• v.48 no.4
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• pp.179-184
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• 2015

Quadrupole Mass Spectrometers (QMS) is a very useful tool in vacuum process diagnosis. Tungsten filament based ion sources are vulnerable to contamination from process gas monitoring. Common symptoms of quadrupole mass spectrometer malfunction is appearance of unwanted contaminant mass peaks or no detection of any ion peaks. We disassembled used quadrupole mass spectrometer and found out black insulating deposits on inside of ion source parts. Five steps of cleaning procedure were applied and almost full restoration of functions were confirmed in two types of closed ion source quadrupole mass spectrometer. By using a numerical modeling (CFD-ACE+) technique, the electric potential profile of ion source with/without insulating deposit was calculated and showed the possibility of quadrupole mass spectrometer malfunction by the deterioration of designed potential profile inside the ion source.

• Analytical Science and Technology
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• v.12 no.2
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• pp.94-98
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• 1999

An analysis method of components and isotopic compositions of low pressure gases from nuclear fuel rod using quadrupole mass spectrometer was studied. The calibration curves of each gas in pure and mixtures of He, $N_2$, $O_2$, Ar, Kr and Xe were obtained as a function of pressure and concentration, respectively. Effect of molecular leak, located between sample chamber and analyser chamber, on the sensitivites was also studied. The results suggested that samples could be analysed accurately at the same analytical condition as that of synthetic gas mixture. The difference of sensitivities among isotopes of Kr and Xe was not observed in the range of measured pressure.

• Journal of the Korean Chemical Society
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• v.39 no.12
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• pp.902-909
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• 1995

Detection limit as well as calibration curves on organophosphorus pesticide(dimethoate, diazinon, parathion-methyl, fenitrothion, malathion) and BHCs were measured for evaluation of utility on qualitative or quantitative analysis of pesticides with ion Trap mass spectrometer and quadrupole mass spectrometer. As ionization source, EI and CI were adopted for qualitative analysis of pesticides by comparison of each fragmentation pattern. At the same time, the utility as trace analysis techniques through scan or selected ion monitoring(SIM) mode was evaluated. With ion trap for all pesticides, detection limit(DL, 1 ${\mu}L$ injection) on scan mode was ranged 0.008∼0.225 ng at signal to noise ratio 3. With quadrupole DL on scan mode was ranged 0.23∼3.1 ng over 0.032∼0.68 ng on SIM mode. The calibration curve with ion trap generated good linearity over 0.99 as correlation coefficient. As clean up procedure, Bio Beads S-X3 was used for the separation of oils from five organophosphorous pesticides in flour extractant showing more than 80% as recovery at most cases. In case of BHCs in jinseng with Florisil column, the recovery of pesticides has been 60% to 90%.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.619-623
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• 2007

Synthesis of 4-substituted 3-exo-methylenechroman derivatives was carried out by the n-Bu3SnH-mediated vinyl radical cyclization as the key step starting from various salicylaldehydes.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.91-98
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• 2007

The Korea Research Institute of Standards and Science (KRISS) has developed a residual gas analyzer (RGA) calibration system and measured gas sensitivities for two different types QMSs using nitrogen, argon, and helium. Different gas sensitivities were identified according to mass and pressure, so it was revealed that the gas sensitivity correction is necessary for proper use of mass spectrometers.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.142-150
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• 2015

A failure analysis of tungsten filaments used in quadrupole mass spectrometer for plasma process monitoring was carried by using SEM and EDS. Failed at high temperature, filaments showed two kinds of failure modes. The one is that diameter of filament became thinner gradually and finally snapped. The other is that filament abruptly snapped almost at a right angle. The EDS analysis showed Fe and C, including W and Fe, on the surface of failed filament. when failed filaments were treated with plasma in mixture of Ar and $CF_4$, the amount of Fe and C decreased. The failure analysis of filament showed that the cause of filament failure is thermal evaporation and grain growth of tungsten at high temperature.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.4
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• pp.204-208
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• 2006

In this study, we investigated the ion energy distributions in a chlorine based inductively coupled plasma by quadrupole mass spectrometer with an electrostatic ion energy analyzer. Ion energy distributions are presented for various plasma parameters such as $BCl_3/Ar$ gas mixing ratio, RF power, and process pressure. As the $BCl_3/Ar$ gas mixing ratio and process pressure decreases, and RF power increases, the saddle-shaped structures is enhanced. The reason is that there are ionized energy difference between $BCl_3$ and Ar, change of plasma potential, alteration of mean free path. and variety of ion collision in the sheath.