• 한국진공학회지
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• 제21권6호
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• pp.295-300
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• 2012

지름이 각각 10 mm와 20 mm인 피스톤과 진공장치를 이용해서 발생된 유량과 이온게이지의 압력을 측정하여 비교하는 방법으로 개발 중인 오일유량계의 성능을 예비 평가하였다. 큰 피스톤의 유량 발생 범위는 $1{\times}10^{-1}Pa{\cdot}L/s{\sim}1.2Pa{\cdot}L/s$이었고 작은 피스톤의 유량발생 범위는 $5.3{\times}10^{-1}Pa{\cdot}L/s{\sim}1.05Pa{\cdot}L/s$이었으며, 이 구간에서의 반복성과 직선성은 비교적 좋았다. 개발 중인 오일유량계는 국가 리크표준기로서 앞으로 표준리크를 교정하는데 활용할 계획이다.

• Mass Spectrometry Letters
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• 제6권3호
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• pp.71-74
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• 2015

Low temperature plasma (LTP) ionization mass spectrometry (MS) is one of the widely used ambient analysis methods which allows soft-ionization and rapid analysis of samples in ambient condition with minimal or no sample preparation. One of the major advantages of LTP MS is selective analysis of low-molecular weight, volatile and low- to medium-polarity analytes in a sample. On the contrary, the selectivity for particular class of compound also implies its limitation in general analysis. One of the critical factors limiting LTP ionization efficiency is poor desorption of analytes with low volatility. In this study, a home-built LTP ionization source with Peltier heating sample stage was constructed to enhance desorption and ionization efficiencies of analytes in a sample and its performance was evaluated using standard mixture containing fatty acid ethyl esters (FAEEs). It was also used to reproduce the previous bacterial identification experiment using pattern-recognition for FAEEs. Our result indicates, however, that the bacterial differentiation from FAEE pattern recognition using LTP ionization MS still has many limitations.

• Bulletin of the Korean Chemical Society
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• 제25권10호
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• pp.1508-1512
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• 2004

A gas chromatography/mass spectrometric (GC/MS) method has been developed for the determination of trace mono-n-butyltin (MBT), di-n-butyltin (DBT), and tri-n-butyltin (TBT) compounds in sediments. Samples were extracted by 10% acetic acid in methanol containing 0.03% tropolone and were then derivatized for GC/MS analysis. Ethylation by sodium tetraethylborate and phenylation by sodium tetraphenylborate were evaluated as a derivatization reaction of the organotins in sample extract. n-Hexane was added into reaction media in the beginning of the reaction for the continuous extraction of derivatized organotins. Ethylation requires less than 2 hours to get proper derivatization yields for MBT, DBT, and TBT altogether and produces relatively low amounts of side reaction products. Compared to ethylation, phenylation requires much longer time but provides relatively lower yield and produces considerable amounts of side reaction products. Therefore, the ethylation reaction was applied for the analysis of organotin compounds in sediment. An isotope dilution mass spectrometric (IDMS) method based on GC/MS has been applied to the accurate determination of DBT compounds in the sediments. The IDMS results from the analyses of sediment samples showed a reasonable repeatability and a good agreement with the values obtained by IDMS based on liquid chromatography/induced coupled plasma/mass spectrometry.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.821-827
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• 2014

An isotope dilution liquid chromatography tandem mass spectrometry (ID LC-MS/MS) method has been developed and applied to the determination of arsenobetaine (AsB, ${(CH_3)_3}^+AsCH_2COO^-$) from oyster candidate certified reference material (CRM). The exact matching isotope dilution approach was adopted for accurate determination of AsB using $^{13}C_2$-labeled AsB as an internal standard. Efficiencies of different AsB extraction methods were evaluated using a codfish reference material and a simple sonication method was selected as the method of choice for the certification of the oyster candidate CRM. The hydrophilic interaction liquid chromatography (HILIC) combined with electrospray ionization tandem mass spectrometry (ESI/MS/MS) in selected reaction monitoring (SRM) mode was optimized for adequate chromatographic retention and robust quantification of AsB from codfish and oyster samples. By analyzing 12 subsamples taken from each 12 bottles systematically selected from the whole oyster CRM batch, the certified value of AsB was determined as $6.60mg{\cdot}kg^{-1}{\pm}0.31mg{\cdot}kg^{-1}$ and it showed excellent between-bottle homogeneity of less than 0.42%, which is represented by relative standard deviation of 12 bottles from the CRM batch. The major source of uncertainty was the certified value of the AsB standard solution.

• 한국의학물리학회지:의학물리
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• 제23권4호
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• pp.285-291
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• 2012

Si(Li) 검출기를 이용해 한국표준과학연구원에서 보유한 베타선 선원인 $^{147}Pm$, $^{85}Kr$, $^{90}Sr+^{90}Y$ 선원의 순수 베타선 에너지 스펙트럼을 측정하였고 이 측정 스펙트럼에 대한 잔여에너지와 질량충돌저지능비를 산출하였다. 베타선의 잔여에너지는 $^{147}Pm$, $^{85}Kr$, $^{90}Sr+^{90}Y$ 선원에 대하여 각각 0.14, 0.57, 0.93 MeV으로 평가되었고 질량충돌저지능비는 각각 1.123, 1.120, 1.109이었다.

• 소음진동
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• 제4권1호
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• pp.83-88
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• 1994

물체를 한 위치에서 타 위치로 잔류 진동없이 움직이려 하는 경우가 많다. 본 논문에서는 한 질량이 다른 질량과 스프링에 의해 움직이는 경우와 진자가 지지 점의 운동에 의해 움직이는 경우에 관해 논하였다. 각 경우에 있어서 시스템은 정지 상태에서 출발한 후 최종위치에서 다시 멈추는 것으로 간주하였다. 본 논문에 주어진 운동방식에 대한 기본 전략은 엔진 캠-구동자 형태의 설계시 단순화된 모형으로부터 도출되었다. 이와 같은 형태로 시스템을 움직이는데 필요한 힘과 최대힘 및 그때 소요되는 시간이 계산되었다.

• 한국입자에어로졸학회지
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• 제8권1호
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• pp.29-35
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• 2012

The Faraday cup electrode of different size has been developed and evaluated to investigate the diffusion effect of particles by Brownian motion in a particle beam mass spectrometer(PBMS). Particles which focused and accelerated by aerodynamic lens are charged to saturation in an electron beam, and then deflected electrostatically into a Faraday cup detector for measurement of the particle current. The concentration of particles is converted from currents detected by Faraday cup. Measurements of particle current as a function of deflection voltage are combined with measured relationships between particle velocity and diameter, charge and diameter, and mass and diameter, to determine the particle size distribution. The particle currents were measured using 5, 10, 20, 40 mm sized Faraday cup that can be move to one direction by motion shaft. The current difference for each sizes as a function of position was compared to figure out diffusion effect during transport. Polystyrene latex(PSL) 100, 200 nm sized standard particles were used for evaluation. The measurement using 5 mm sized Faraday cup has the highest resolution in a diffusion distance and the smaller particles had widely diffused.

• 한국공간구조학회논문집
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• 제21권1호
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• pp.95-104
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• 2021

As people's living standards and cultural standards have developed, interest in culture and art has increased, and the demand for large space structures where people can enjoy art, music, and sports has increased. As it accommodates a large number of personnel, it is most important to ensure safety of large spatial structures, and can be used as a space where people can evacuate in case of a disaster. Large spatial structures should be prepared for earthquake loads rather than wind loads. In addition to damage to the structure due to earthquakes, there are cases in which it was not utilized as a space for evacuation due to the fall of objects installed on top of the structure. Therefore, in this study, the dome-shaped large spatial structure is generalized and the displacement response according to the number of installations, position and mass is analyzed using a tuned mass damper(TMD) that is representative vibration control device.

• Mass Spectrometry Letters
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• 제14권4호
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• pp.178-185
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• 2023

QuEChERS is used worldwide as a universal sample preparation method with many benefits, such as being quick, easy, cheap, effective, rugged and safe. This study examined whether QuEChERS can be employed in isotope dilution mass spectrometry (ID-MS) for accurate analysis of pesticides in food. The ratios of fortified values and measured values of malathion and fenitrothion using the QuEChERS method were compared with those using the solid phase extract (SPE) method which was previously used in this laboratory. The separations of the two pesticides on DB-5MS and VF-1701MS columns were compared. Malathion and fenitrothion were fortified into kimchi cabbage and pretreated with the QuEChERS method and the SPE method. The results obtained using the DB-5MS column varied according to the sample preparation method, column and pesticide level. Using the VF-1701 column, ratios were 98-102% by both QuEChERS and Carb/NH₂ SPE method for all fortification level. Malathion and fenitrothion were fortified into strawberry samples for comparison with kimchi cabbage. The results for the strawberry samples indicated that the ratios were not influenced by the sample preparation methods or GC column. The QuEChERS method could be acceptable in the ID-MS method for pesticide residue analysis in food, however other conditions should be carefully considered for accurate determination, such as the column, amount of analyte and food matrix.

• Mass Spectrometry Letters
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• 제5권1호
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• pp.30-33
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• 2014

A solid phase extraction (SPE) method was optimized for the quantitative analysis of perfluorooctanoic acid (PFOA) in serum using hydrophilic-lipophilic balance SPE and LC-MS/MS. Fetal bovine serums spiked with $^{13}C_8$-PFOA before or after SPE were used as test samples for evaluation of the SPE efficiency. Simultaneous evaluation of matrix effects and absolute SPE recovery for $^{13}C_8$-PFOA in serum using different sample pre-treatments and SPE conditions allowed optimization of SPE process efficiency with minimal matrix effect and decent SPE recovery. Introduction of protein precipitation as a sample pre-treatment procedure for serum samples before SPE generally decreased matrix effect in LC-MS/MS analysis and provided more stable recovery of PFOA.