• 한국결정성장학회지
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• 제7권3호
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• pp.465-472
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• 1997

본 연구는 전기 장에서 광여기 탈착과 이온화에 근거한 표면연구의 새로운 장치를 개발하고 시험한 결과를 보고한다. 실험장치의 분해능을 테스트 하기 위해 텡스텐(110)면에서 흡착기체 $H_2$ 와 He 가스를 조사하였으며, 팁의 온도는 80 K이었다. 장세기가 10 V/nm에서 50 V/nm사이에서 사용한 파장은 193 nm이였으며, 텡스텐(110)면에 가스가 흡착되었을때 레이저빔의 전자적인 여기로 부터 흡착가스와 팁에서 여러종류의 이온들이 형성되었다($H_2^+, CO^+, H_2O^+, He^+, W^{3+}$ 그리고 $W^{2+}$). 전체 mass spectrum의 기록은 Transient recorder가 가능하게 한다.

• Smart Structures and Systems
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• 제21권4호
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• pp.449-467
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• 2018

In this paper, a theoretical and numerical study on bridge simultaneous damage detection procedure for identifying both the system parameters and input excitation mass, are presented. This method is called 'Adjoint Variable Method' which is an iterative gradient-based model updating method based on the dynamic response sensitivity. The main advantage of proposed method is inclusion of an analytical method to augment the accuracy and speed of the solution. Moving mass is a model which takes into account the inertia effects of the vehicle. This interaction model is a time varying system and proposed method is capable of detecting damage in this variable system. Robustness of proposed method is illustrated by correctly detection of the location and extension of predetermined single, multiple and random damages in all ranges of speed and mass ratio of moving vehicle. A comparison study of common sensitivity and proposed method confirms its efficiency and performance improvement in sensitivity-based damage detection methods. Various sources of errors including the effects of measurement noise and initial assumption error in stability of method are also discussed.

• Mass Spectrometry Letters
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• 제6권1호
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• pp.7-12
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• 2015

In the present study, we proposed a simple ESI-MS model for determining $Zn^{2+}$ binding (or dissociation) constants for zinc finger peptides (ZFPs) with a unique ${\beta}{\beta}{\alpha}$ fold consensus. The ionization efficiency (response) factors for this model, i.e., ${\alpha}$ and ${\beta}$, could be determined for ZiCo ZFP with a known $Zn^{2+}$ binding constant. We could determine the binding constants for other ZFPs assuming those with a ${\beta}{\beta}{\alpha}$ consensus conformation have the same ${\alpha}/{\beta}$ response ratio. In general, the ZPF dissociation constants exhibited $K_d$ values of $10^{-7}{\sim}10^{-9}M$, while $K_d$ values for a negative control non-specific $Zn^{2+}$ peptides were high, e.g., $5.5{\times}10^{-6}M$ and $4.3{\times}10^{-4}M$ for BBA1 and melittin, respectively.

• The Korean Journal of Physiology and Pharmacology
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• 제11권4호
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• pp.155-161
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• 2007

In order to characterize the role of sympathetic activity in obesity, we repeatedly assessed sympathetic activity via power spectral analyses of heart rate variability in the same subjects at 7, 11, 25, and 60 weeks, using monosodium glutamate (MSG)-induced obese and control rats. The effects of lower sympathetic activity on obesity were also evaluated. Fat mass in MSG rats was already higher at 7 weeks, but the sympathetic activity did not differ between 7 and 25 weeks. Between 25 and 60 weeks, the increase in fat mass, food efficiency, and body weight gain was higher in MSG rats. The increase in sympathetic activity between 25 and 60 weeks and sympathetic activity at 60 weeks were lower in MSG rats. Fat mass at 60 weeks was inversely correlated with changes in sympathetic activity between 25 and 60 weeks. Reduced plasma epinephrine levels by bilateral adrenal demedullation induced increase of fat mass. In, an attenuated increase of sympathetic activity with age may partly be responsible for aggravated obesity in MSG rats. Additionally, reduced sympathetic activity per se induced obesity in rats. These results suggest that lower sympathetic activity contributes to obesity in rats.

• 디자인학연구
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• 제19권1호
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• pp.335-340
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• 2006

본 연구는 주거환경 중 욕실에서 사용하는 세면대의 디자인 개발로서, 생산성 향상에 따른 생산자 만족과 사용자의 다양성 수용이라는 소비자의 만족을 동시에 충족시키는 매스-커스터마이제이션(mass-customization) 개념을 도입하여, 다양한 특성의 조합 표현이 가능한 확장성(expansibility) 기반의 디자인 개발에 관한 것이다. 제품의 속성상 특히 기능적인 부분과 감성적인 부분의 적절한 균형에 중점을 두었다. 효율적인 디자인 개발 프로세스를 위하여 사용자 행동 분석을 통해 잠재되어 있는 소비자의 욕구를 도출하였고, 전반적인 주거환경과 욕실, 세면대 디자인에 대한 트랜드 분석을 기초로 제품의 특성에 맞는 새로운 소재의 응용과 그 조합을 개발하였으며, 사용자의 다양한 조건에 따른 확장성을 높이기 위하여 모듈라 디자인(modular design)을 사용하였다.

• Mass Spectrometry Letters
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• 제5권2호
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• pp.52-56
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• 2014

Glycated hemoglobin (HbA1c) is used as an index of mean glycemia over prolonged periods. This study describes an optimization of enzyme digestion conditions for quantification of non-glycated hemoglobin (HbA0) and HbA1c as diagnostic markers of diabetes mellitus. Both HbA0 and HbA1c were quantitatively determined followed by enzyme digestion using isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) with synthesized N-terminal hexapeptides as standards and synthesized isotope labeled hexapeptides as internal standards. Prior to quantification, each peptide was additionally quantified by amino acid composition analysis using ID-LC-MS/MS via acid hydrolysis. Each parameter was considered strictly as a means to improve digestion efficiency and repeatability. Digestion of hemoglobin was optimized when using 100 mM ammonium acetate (pH 4.2) and a Glu-C-to-HbA1c ratio of 1:50 at $37^{\circ}C$ for 20 h. Quantification was satisfactorily reproducible with a 2.6% relative standard deviation. These conditions were recommended for a primary reference method of HbA1c quantification and for the certification of HbA1c reference material.

• Journal of Advanced Marine Engineering and Technology
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• 제25권6호
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• pp.1341-1352
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• 2001

Vacuum freeze drying process by which frozen water in a drying material is removed sublimation under vacuum condition, is now applied to various industrial field such as the manufacturing and packaging of pharmaceuticals in pharmaceutical industry, the drying of bio- products in bio-technology industry, the treatment of various quality food stuff in food technology, and so on. The Knowledge about the heat and mass transfer characteristics related with the vacuum freeze drying process is crucial to improve the efficiency of the process as well as the quality of dried products. In spite of increasing needs for understanding of the process, the research efforts in this fields are still insufficient. In this paper, a numerical code that can predict primary drying in a vial is developed based on the finite volume method with a moving grid system. The calculation program can handle the axis- symmetric and multi-dimensional characteristics of heat and mass transfer of the vial freeze drying process. To demonstrated the usefulness of the present analysis, a practical freeze drying of skim Milk solution in a vial is simulated and various calculation results are presented.

• Mass Spectrometry Letters
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• 제2권3호
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• pp.65-68
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• 2011

The effects of column length and particle size on the efficiency of separation and characterization of phospholipids (PLs) are investigated using nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS-MS). Since PLs are associated with cell proliferation, apoptosis, and signal transduction, it is of increasing interests in lipidomics to establish reliable analytical methods for the qualitative and quantitative profiling of PLs related to biomarker development in adult diseases. Due to the complexity of PLs, the preliminary separation of PLs is necessary prior to MS analysis. In this study, length of capillary column and the particle size of reversed phase ($C_{18}$) packing materials are varied to find a reliable condition for the high speed and high resolution separation using 8 PL standard mixtures. From experiments, it was found that a capillary column of nLC-ESI-MS-MS analysis for PL mixtures can be minimized to a 5 cm long pulled tip column packed with 3 ${\mu}m$ $C_{18}$ particles without losing resolution.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.477-482
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• 2011

The structural analysis of polytrimethylene terephthalate (PTT) and characterization of the hydrolytic degradation products after acid hydrolysis were performed using MALDI-TOF mass spectrometry. Mass spectra of the PTT samples were analyzed using a self-calibration method as well as an internal calibration method with standard materials of known masses. PTT structures constituting the samples were determined from the analyses of the spectra, and their relative compositions were estimated. The MALDI-TOF mass spectra of the acid-hydrolyzed PTT sample showed three main series of oligomer products with different end groups in accordance with the hydrolysis schemes. From the spectra of both $Na^+$ and $K^+$ adducts, it was concluded that the PTT samples have higher affinity for $Na^+$ compared with $K^+$ and therefore show higher ionization efficiency with sodium ions when dithranol is used as a matrix. Two different wavelength laser beams ($\lambda$ = 337 nm and 355 nm) were tested and it was observed that the 355 nm beam was more efficient in obtaining the MALDI spectra of PTT using dithranol as a matrix under our experimental conditions.

• 천문학회보
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• 제42권1호
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• pp.49.1-49.1
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• 2017

In order to investigate the origin of multiple stellar populations in the halo and bulge of the Milky Way, we have constructed chemical evolution models for the low-mass proto-Galactic subsystems such as globular clusters (GCs). Unlike previous studies, we assume that supernova blast waves undergo blowout without expelling the pre-enriched gas, while relatively slow winds of massive stars, together with the winds and ejecta from low and intermediate mass asymptotic giant branch stars, are all locally retained in these less massive systems. We first applied these models to investigate the origin of super-helium-rich red clump stars in the metal-rich bulge as recently suggested by Lee et al. (2015). We find that chemical enrichments by the winds of massive stars can naturally reproduce the required helium enhancement (dY/dZ = 6) for the second generation stars. Disruption of these "building blocks" in a hierarchical merging paradigm would have provided helium enhanced stars to the bulge field. Interestingly, we also find that the observed Na-O anticorrelation in metal-poor GCs can be reproduced, when multiple episodes of starbursts are allowed to continue in these subsystems. Specific star formation history with decreasing time intervals between the stellar generations, however, is required to obtain this result, as would be expected from the orbital evolution of these subsystems in a proto-Galaxy. The "mass budget problem" is also much alleviated by our models without ad-hoc assumptions on star formation efficiency and initial mass function.