• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.329-329
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• 2000

In this paper, a spindle system using an electromagnetic exciter is proposed to compensate a spindle disturbance such as unbalance and machining force etc A spindle compliance can be readily varied with a disturbance which is generated by the interact ion between the spindle / workpiece structure and the cutting process dynamics. The varied compliance is one of the major constraints that deteriorates the surface quality of workpiece. This paper suggests a compliance compensation by using the EME in the proposed spindle system. To compensate the varied compliance, firstly a spindle system modeling was conducted by using the bond graph. Then the model is simulated by numerical analysis method and an optimal EME position is determined to compensate a disturbance effectively through simulation, which makes the bearing load to be minimized

• 생약학회지
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• 제34권3호통권134호
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• pp.246-249
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• 2003

The major polysaccharide, named EAP, was purified from the aerial parts of Eclipta alba by Sepharose CL-2B ion exchange chromatography and recycling HPLC. The molecular weight of EAP was estimated to be 20911.9 D by MALDI-TOF MS. In addition, the sugar composition was determined to be arabinose (23.6%), mannose (24.8%), galactose (12.3%), and glucose (41.3%), respectively, by GC analysis. The EAP decreased the blood sugar level, which was induced by alloxan in rats, dose dependently.

• Bulletin of the Korean Chemical Society
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• 제20권1호
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• pp.59-64
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• 1999

Based on the study of hydrolysis behaviour of U(Ⅵ) ion and major fission product metal ions such as Cs(Ⅰ), Ce(Ⅲ), Nd(Ⅲ), Mo(Ⅵ), Ru(Ⅱ), and ZR(Ⅳ) in the titration media, the performance of noncomplexing-alkalimetric titration method for the determination of free acid in the presence of these metal ions was investigated and its results were compared to those from the completing methods. The free acidities could be determined as low as 0.05 meq in uranium solutions in which the molar ratio of U(Ⅵ)/H+ was less than 5, when the end-point of titration was estimated by Gran plot. The biases in the determinations were less than 1% and about +3% respectively for 0.4 meq and 0.05 meq of free acid at the U(Vl)/H+ molar ratio of up to 5. Applicability of this method to the determination of free acid in spent fuel solutions was confirmed by the analysis of nitric acid content in simulated spent fuel solutions and in a real spent fuel solution.

• 한국대기환경학회지
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• 제13권1호
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• pp.9-18
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• 1997

Precipitation samples were collected by the wet- only event sampling method from Seoul during September 1991 to April 1995. These samples were analyzed for the concentrations of the major ionic components (N $O_3$$^{[-10]}$ , N $O_2$$^{[-10]}$ , S $O_4$$^{2-}$, C $l^{[-10]}$ , $F^{[-10]}$ , N $a^{＋}$, $K^{+}$, $Ca^{2＋}$, $Mg^{2＋}$, and N $H_4$$^{＋}$), pH, and electric conductivity. During the study period, a total of 182 samples were collected, but only 163 samples were used for the data analysis via quality assurance of precipitation chemistry data. The volume-weighted pH was found to be 4.7. The major acidifying species from our precipitation studies were identified to be non-seasalt sulfate (84$\pm$9 $\mu$eq/L) and nitrate (24$\pm$2 $\mu$eq/L) except for chloride. Because the Cl/Na ratio in the precipitation was close to the ratio in seawater. If all of the non-seasalt sulfate and nitrate were in the form of sulfuric and nitric acids, the mean pH in the precipitation could have been as low as 3.7 lower than the computed value. Consequently, the difference between two pH values indicate that the acidity of precipitation was neutralized by alkaline species. The equivalent concentration ratio of sulfate to nitrate was 3.5, indicating that sulfuric and nitric acids can comprise 78％ and 22％ of the precipitation acidity, respectively. Analysis of temporal trend in the measured acidity and ionic components were also performed using the linear regression method. The precipitation acidity generally showed a significantly decreasing trend, which was compatible with the pattern of the ratio (N $H_4$$^{＋}$＋C $a^{2＋}$)/ (nss-S $O_4$$^{2-}$＋N $O_3$$^{[-10]}$ ).).

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1409-1412
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• 2014

Sex hormones are important metabolites in vertebrates' development and reproduction. For rapid screening sex hormones, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is one of the promising analytical platforms, but MALDI MS faces many challenges in detecting steroids such as low ionization efficiency and matrix background interference. One potential strategy to overcome matrix interference in the low m/z region is using a cyclodextrin (CD)-supported matrix for steroid analysis since CD-supported matrixes are known to effectively suppress matrix-related ion signals. In this study, we aimed to find the optimal CD-supported matrix for the analysis of the nonderivatized sex steroids. Our results showed that the ${\alpha}CD$-supported 2,5-dihydroxybenzoic acid (DHB) matrix efficiently ionized all three major classes of sex hormones, estrogens, androgens, and progestagens, with low or no matrix background and also with high sensitivity. In addition, the ${\alpha}CD$-supported DHB matrix mainly generated molecular ions or protonated ions of sex hormones, and this enabled us to obtain information-rich tandem mass spectra which potentially lead to unambiguous identification of steroid species from complex metabolite mixtures.

• Toxicological Research
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• 제29권2호
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• pp.107-114
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• 2013

Mass spectrometry (MS) is a very powerful instrument that can be used to analyze a wide range of materials such as proteins, peptides, DNA, drugs, and polymers. The process typically involves either chemical or electron (impact) ionization of the analyte. The resulting charged species or fragment is subsequently identified by the detector. Usually, single mass uses source-induced dissociation (SID), whereas mass/mass uses collision-induced dissociation (CID) to analyze the chemical fragmentations Each technique has its own advantages and disadvantages. While CID is most effective for the analysis of pure substances, multiple-step MS is a powerful technique to get structural data. Analysis of veterinary drugs ampicillin, chloramphenicol, ciprofloxacin, and oxytetracycline serves to highlight the slight differences between SID and CID. For example, minor differences were observed between ciprofloxacin and oxytetracycline via SID or CID. However, distinct fragmentation patterns were observed for ampicllin depending on the analysis method. Both SID and CID showed similar fragmentation spectra but different signal intensities for chloramphenicol. There are several factors that can influence the fragmentation spectra, such as the collision energy, major precursor ion, electrospray mode (positive or negative), and sample homogeneity. Therefore, one must select a fragmentation method on an empirical and case-by-case basis.

• Journal of Microbiology and Biotechnology
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• 제16권11호
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• pp.1740-1746
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• 2006

Enrichment techniques led to the isolation of a Pseudomonas sp. strain P2 from municipal waste-contaminated soil sample, which could utilize different isomers of a commercial mixture of 4-nonylphenol when grown in the presence of phenol. The isolate was identified as Pseudomonas sp., based on the morphological, nutritional, and biochemical characteristics and 16S rDNA sequence analysis. The ${\beta}$-ketoadipate pathway was found to be involved in the degradation of phenol by Pseudomonas sp. strain P2. Gas chromatography-mass spectrometric analysis of the culture media indicated degradation of various major isomers of 4-nonylphenol in the range of 29-50%. However, the selected ion monitoring mode of analysis of biodegraded products of 4-nonylphenol indicated the absence of any aromatic compounds other than those of the isomers of 4-nonylphenol. Moreover, Pseudomonas sp. strain P2 was incapable of utilizing various alkanes individually as sole carbon source, whereas the degradation of 4-nonylphenol was observed only when the test organism was induced with phenol, suggesting that the degradation of 4-nonylphenol was possibly initiated from the phenolic moiety of the molecule, but not from the alkyl side-chain.

• 대한의생명과학회지
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• 제21권4호
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• pp.233-240
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• 2015

Some virulence proteins of Helicobacter pylori, such as vacuolating cytotoxic protein A (VacA) and cytotoxin-associated gene protein A (CagA) have been reported to be causative agents of various gastric diseases including chronic gastritis, gastric ulcer or gastric adenocarcinoma. The expression level of these virulence proteins can be regulated when H. pylori is exposed to the antibacterial agent, cyanidin 3-O-glucoside (C3G) as previously reported. In this study, we analyzed the quantitative change of various virulence proteins including CagA and VacA by C3G treatment. We used 2-dimensional electrophoresis (2-DE) to analyze the quantitative change of representative ten proteome components of H. pylori 60190 ($VacA^+/CagA^+$; standard strain of Eastern type). After 2-DE analysis, spot intensities were analyzed using ImageMaster$^{TM}$ 2-DE Platinum software then each spot was identified using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) or peptide sequencing using Finnigan LCQ ion trap mass spectrometer (LC-MS/MS). Next, we selected major virulence proteins of H. pylori among quantitatively meaningful ten spots and confirmed the 2-DE results by Western blot analysis. These results suggest that cyanidin 3-O-glucoside can modulate a variety of H. pylori pathogenic determinants.

• 자원환경지질
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• 제41권1호
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• pp.47-56
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• 2008

본 연구에서는 달천 폐광산 지역 내 25개 지점에서 현장수질(pH, Eh)을 측정되었고, 41개 지점에서 지하수를 채수하여 주이온 성분을 분석되었다. pH와 Eh성분은 모두 사문암 지역에서 가장 높았으며, pH는 약알칼리성에서 중성의 범위로 나타났다. 연구지역 내 지하수는 탄산염암과의 반응에 의한 산화 환원 환경이 지배적이었으며, 다른 암종에 의한 영향은 매우 적은 것으로 나타났다. 연구지역의 지하수 중 양이온은 $Ca^{2+},\;Mg^{2+}$, 음이온은 $SO_4^{2-}$ 성분이 높게 나타났다. 이는 탄산염암과 사문암, 유비철석과 황철석에 함유된 황 성분이 지하수에 다량 용해되었기 때문이다. 지하수내 이온성분 사이의 상관계수는 광미적재지에서 $Ca^{2+}$와 $SO_4^{2-}$ 성분이 0.95, $Ca^{2+}$와 $Mg^{2+}$ 성분이 0.86, $Mg^{2+}$와 $SO_4^{2-}$ 성분이 0.85로서 높게 나타났다. 또한 기반암 지하수에서는 $Mg^{2+}$와 $SO_4^{2-}$ 성분이 0.86, $Ca^{2+}$와 $SO_4^{2-}$ 성분이 0.68 정도로 나타났다. 양이온 중 $Ca^{2+}$ 성분이 광미적재지에서 $46.85\sim323.58mg/L$, 기반암에서 $3.18{\sim}207.20mg/L$로서 가장 넓은 농도 범위를 나타내었으며, 음이온 중 $SO_4^{2-}$ 성분이 광미적재지에서 $21.54{\sim}1673.17mg/L$, 기반암은 $2.04{\sim}1024.64mg/L$로 가장 넓은 농도 범위를 나타내었다. 대수층 매질 종류에 따른 파이퍼 다이아그램 분석 결과, 광미적재지는 Ca-$SO_4$형, 사문암 지역은 Mg-$SO_4$형과 Mg-$HCO_3$형, 탄산염암 지역은 Ca-$HCO_3$형, 혼펠스 지역은 Na-K형과 $CO_3+HCO_3$형이 우세한 것으로 나타났다. 본 연구를 통해 달천 폐광산 지역의 광미적재지에서 $Ca^{2+},\;Mg^{2+}$ 및 $SO_4^{2-}$ 성분이 지하수에 다량 용해되어 지하수의 주 흐름 방향에 위치한 기반암 지하수에 유입되었음을 알 수 있었다.

• 방사성폐기물학회지
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• 제4권1호
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• pp.59-64
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• 2006

원자력 발전소의 증기발생기 슬러지 중에서는 이온교환수지가 발견되어서는 안 된다. 원자력 발전소의 증기발생기 슬러지 시료 중에서 발견되어 이온교환수지 입자로 의심되는 구형 입자들의 특성을 측정하였다. 미세조작기술을 이용하여 광학현미경으로 입자 크기 분포를, EPMA로 구형입자의 성분을, 그리고 IR 분광 스펙트럼 비교에 의하여 이온교환수지 여부를 조사하였다. 슬러지의 입자 크기는 1 내지 $200{\mu}m$이었으나 구형 입자는 $40-500{\mu}m$이었다. 슬러지의 주요 불순원소가 Si, Al, Mn, Cr, Ni, Zn, 그리고 Ti이었으나 구형 입자는 Si, Cu, Zn 이었다. 주성분은 두 경우 모두 철이었다. 구형 입자의 IR 분광스펙트럼은 증기발생기 취출수 정화계통에서 사용하는 이온교환수지의 스펙트럼과 비교했을 때 서로 일치하지 않음을 보여주었다. 이 결과들은 증기발생기 슬러지 시료 중에서 발견된 구형 입자가 이온교환수지는 아니며 일반적인 슬러지가 생성되는 과정에서 작은 슬러지 입자들이 크게 뭉쳐서 생성된 것임을 나타내고 있다.