• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.113-116
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• 2008

본 연구에서는 차량-교량간 상호작용효과가 교량의 동적거동에 미치는 영향을 분석하기 위한 차량 주행 하중에 대한 실험적 및 이론적 연구를 수행하였다. 이를 위하여 차량 교량간 상호작용이 포함된 이동질량형 윤하중 실험기를 단순교형식 교량에 적용하여 반복주행실험을 수행하였다. 이동질량 반복 주행실험 결과를 분석하여 차량-교량간의 상호작용을 포함한 가속도 형태의 실동주행차량가속도를 규명하였다. 규명된 차량의 실동주행차량가속도를 범용 해석프로그램에 적용하여 차량-교량 상호작용을 재현할 수 있었다. 또한 차량주행시 교량의 사용성평가에 대한 기본자료를 판단할 수 있었다.

• The Journal of the Petrological Society of Korea
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• v.10 no.3
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• pp.148-156
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• 2001

We report $^{230}Th/^{234}U$ disequilibrium ages of fracture-filling carbonate veins from the Ipsil and Janghangri fault zones, Gyeongju, Korea by multiple collector inductively coupled plasma mass spectrometry. The U and Th fraction was extracted from totally dissolved samples by rapid and convenient coprecipitation and ion exchange chemistry. The recovery was around 80% for Th and 70% for U. The $^{234}U/^{238}U,\;^{230}Th/^{232}Th$ ratios were analysed for this preconcentrated fraction and the U/Th ratio was directly analysed for untreated sample solution. The $^{234}U-^{230}Th$ system is in secular equilibrium for the Ipsil carbonate samples, supporting previously reported ESR ages. The detrital-corrected $^{230}Th/^{234}U$ age of the Janghangri carbonate samples is $48\pm$41 ka, which constrains the minimum age of the fracture zone.

• Bioinformatics and Biosystems
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• v.1 no.2
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• pp.109-114
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• 2006

In proteomics research, proteins are digested into peptides by an enzyme and in mass spectrometer, these peptides break into fragment ions to generate tandem mass spectra. The tandem mass spectral data obtained from the mass spectrometer consists of the molecular weights of the precursor ion and fragment ions. The precursor ion mass of tandem mass spectrum is the first value that is fetched to sort the candidate peptides in the database search. We look far the peptide sequences whose molecular weight matches with precursor ion mass of the mass spectrum. Then, we choose one peptide sequence that shows the best match with fragment ions information. The precursor ion mass of the tandem mass spectrum is compared with that of the digested peptides of protein database within the mass tolerance that is assigned by users according to the mass spectrometer accuracy. In this study, we used reversed sequence database method to analyze the molecular weight distribution of precursor ions of the tandem mass spectra obtained by the FT LTQ mass spectrometer for human plasma sample. By reinterpreting the precursor ion mass distribution, we could compute the experimental accuracy and we suggested a method to improve the protein identification performance.

• Journal of Space Technology and Applications
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• v.3 no.1
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• pp.86-99
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• 2023

The mass spectrometer, being an essential scientific instrument for uncovering the origin of the solar system and life, has been used since the early 1970s on board spacecraft to obtain information of neutral and ionized elements in the atmosphere and surface of the moon, planets, asteroids, and comets. According to the 4th Basic Plan for the Promotion of Space Development (2023-2027), Korea plans to conduct lunar landing in 2032 and Mars landing in 2045 as the core goals of the plan and focuses on developing the technologies required for unmanned robotic exploration missions. In this regard, it is crucial to develop the technology of a mass spectrometer, which is the most fundamental payload for space exploration for maximized scientific achievements, however never tried before in any domestic space missions. We describe in this paper the principle of a domestically developed quadrupole mass spectrometer, its prototype model, and the test results of its performance. We conclude this paper with intended future improvements.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.6
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• pp.435-443
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• 2008

Purpose: Gated myocardial perfusion SPECT provides not only myocardial perfusion status but also various functional parameters of left ventricle. We compared left ventricular ejection fraction, end-diastolic volume, LV mass by cardiac SPECT using Quantitative Gated SPECT (QGS), 4D-MSPECT software and standard 2D-echocardiography. Materials and Methods: One hundred fourteen patients (male 51, female 63; 29-85 years old, mean $61.3\;{\pm}\;13.3$ years old) with normal perfusion status on Tc-99m tetrofosmin gated myocardial perfusion SPECT were analyzed retrospectively. Ejection fraction (LVEF), End-diastolic volume (LVED), LV mass (LVM) were calculated using QGS, 4D-MSPECT, and LVEF, LVM using 2D-echocardiography. Statistical analysis including Bland-Altman plot was performed using $MedCalc^{(R)}$ (MedCalc software, Mariakerke, Belgium). Results: The correlation of LVEF between methods was good: 0.95/0.96 (stress/rest) between QGS and 4D-MSPECT, 0.79 between QGS and echocardiography, 0.79 between 4D-MSPECT and echocardiography (p<0.001). Using Bland-Altman plot, the 95% confidence interval of agreement between QGS and 4D-MSPECT ranged from -12.7% to 7.3% / from -12.2% to 6.5% (stress/rest). The agreement between QGS and echocardiography, 4D-MSPECT and echocardiography ranged from -17.4% to 24.0%, and -14.8% to 27.0% respectively. The correlation of LVM between methods was also good: 0.95 between QGS and 4D-MSPECT, 0.76 between QGS and echocardiography, 0.73 between 4D-MSPECT and echocardiography (p<0.001). The 95% confidence interval of agreement between QGS and 4D-MSPECT ranged from -33.8g to 14.1g (stress/rest), The 95% confidence interval of agreement between QGS and echocardiography, 4D-MSPECT and echocardiography ranged from -148.7 g to 21.8. g, and -142.8 g to 35.5 g, respectively. Conclusion: There was a good correlation for LVEF, LVEO, LVM among methods (QGS, 4D-MSPECT, echocardiography), but the variance between methods was big. Therefore, the functional parameters by each method cannot be used interchangeably.

• Analytical Science and Technology
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• v.18 no.6
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• pp.483-490
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• 2005

Mass resolution of the time of flight aerosol mass spectrometer for an aerosol component analysis depends on the initial direction and the initial energy of the ions. We have found that the shape of the optimum post focusing electric field is not linear. The maximum electric potential should be applied to the ions whose initial direction is 90 degree. To check on the post focusing effects, we have installed a laser ablation mass spectrometer. By using this LA-MS, we have found that the average energy distribution of the laser ablated ions is 8 eV. To establish the optimum mass resolution, a time delay and a high voltage are needed, and the results of the study show that 1500 nsec, and 3.7 kV are the optimum parameters for our system respectively. The isotope mass signals of copper show a good resolution.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.63-64
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• 2005

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.33-39
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• 2018

An additive noise reduction algorithm for a mass spectrum analyzer is proposed. From the measured ion signal, we first used an estimated threshold from the mode of the measured signal to eliminate background noises with the white Gaussian characteristics. Also, a signal block corresponding to each mass index is constructed to perform a second order curve fitting and a linear approximation to signal block. In this process, the effective signal block composed of only the ion signal can be reconstructed by removing the impulsive noises and the sample signals which are insufficient to be viewed as normal ion signals. By performing curve fitting on the effective signal block, the noise-free mass spectrum can be obtained. To evaluate the performance of the proposed method, a simulation was performed using the signals acquired from the development equipment. Simulation results show the validity of the threshold setting from the mode and the superiority of the proposed curve fitting and linear approximation based noise canceling algorithm.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.608-608
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• 2013

직선운동하는 하전입자의 진행방향에 수직한 평면상에 서로 직교하는 전기장과 자기장을 걸어주면, 하전입자에는 전기장에 의한 힘 $F_E$와 자기장과 속도 v에 의한 로렌츠력 $F_B=q(v{\times}B)$가 동시에 작용하게 된다. 이때 Wien 조건 $F_B=-F_E$를 만족하는 질량 $m_A$과, 에너지 $E_A$를 가지는 하전입자 A는 휘지 않고 직선운동을 계속하나, 하전입자 A와 다른 에너지 $E_B(=E_A+{\delta}E)$나 질량 $m_B$ $(=m_A+{\delta}m)$을 가지는 하전입자는 휘게 되며, 그 휘는 정도는 ${\delta}E$나 ${\delta}m$에 비례하게 된다. 이 현상을 이용하여 다양한 종류의 에너지 또는 질량 분석기가 독일, 미국, 일본 등의 분석기기 선진국에서 개발되어 왔고, 전자현미경의 이미지 필터로도 활용되고 있으며, 통상 EXB 필터 또는 발명자의 이름을 딴 Wien 필터로 불리어지고 있다. $E{\times}B$ 필터는 일반적인 하전입자빔 렌즈와 다른 광학특성을 가진다. 예를 들면 3차 이상의 기하 수차만 가지는 일반 렌즈와는 달리 $F_B$, $F_E$ 전자기력에 의해 다양한 2차 기하 수차를 가지게 되며, 초점거리 등의 1차 광학 특성도 일반 렌즈와는 다른 경향을 보여준다. 본 발표에서는 $E{\times}B$ 필터의 전후로 각각 6극자+4극자를 조합시킨 보정기를 배치시켜 필터의 에너지 분해능의 성능을 향상시킬 수 있음을 빔 궤도 방정식을 분석적으로 계산하여 보여준다. 위 에너지 필터 구성에서 4극자는 1차 광학 특성을 조정하는 역할을 하며 6극자는 2차 수차를 줄여주는 역할을 한다. 수치해석을 통해서는 6극자+4극자를 조합시킨 보정기와 $E{\times}B$ 필터의 좀더 정확한 전극 전압 등의 제어 수치를 추출하고, 빔 궤도 방정식 분석을 통한 수차 보정 알고리즘이 유효함을 보여준다.

• Fire Science and Engineering
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• v.33 no.6
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• pp.80-86
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• 2019

In Korea, a total of 556 chemical accidents occurred from 2012 to 2018 caused by adverse reactions of two or more chemicals, which required significant amounts of time to identify the causative chemicals. Rapid analysis is required for effective incident response and probing. In this study, a quantum transition time-of-flight mass spectrometer was used to identify the causative agents of chemical accidents caused by adverse reactions. The analyzer enabled fast real-time analysis without the need for sample collection and pretreatment. Quantitative and qualitative analysis of most volatile organic compounds with high hydrogen affinity was performed to investigate the cause of the chemical accidents. In fact, in the month of 201◯, methanol and toluene were detected as causative agents of the accident using a quantum transition time mass spectrometer, and were also the cause of the reported odor.