• 한국전자통신학회논문지
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• 제7권2호
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• pp.295-301
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• 2012

본 논문에서는 고속 ADC의 앞단에서 사용하기 위한 1 $V_{pp}$의 입력 신호 범위에서 12 Bit의 해상도를 갖고 100 MS/s의 샘플링 속도에서 동작하는 SHA를 설계하였다. 제안된 시스템은 입력 주파수가 5 MHz, 샘플링 주파수 100 MHz 일 때 SFDR(Spurious Free Dynamic Range)가 약 66.3 dB로 해상도가 떨어졌으나 feedthrough를 제거한 회로는 SFDR이 약 73 dB로 12 bit 해상도를 갖는다.

• 분석과학
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• 제24권3호
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• pp.173-182
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• 2011

약물(Prostanozol)을 복용한 여성을 대상으로 한 뇨시료 중에 함유된 Prostanozol 및 그 대사체들을 검출하기 위해 LC/ESI/MS와 GC/TOF-MS를 이용하여 효과적으로 분리 및 검출하였고, LC/ESI/MS의 질량스펙트럼으로부터는 각각의 분자량을 추정하였으며 GC/TOF-MS로는 이들을 확인하였다. M1은 Prostanozol의 17번 탄소가 케톤기로 치환된 17-keto-Prostanozol, M2는 M1에서 pyrazole nucleus 와 Aring에 한 개의 히드록시기가 치환된 hydroxy-17-keto-Prostanozol, M3는 B-ring 또는 C-ring에 한 개의 히드록시기가 치환된 hydroxy-17-keto-Prostanozol, M4는 한 개의 히드록시기가 D-ring에 치환된 hydroxy-17-keto-Prostsnozol로 확인되었으며 M5는 17번 탄소 위치에 히드록시기를 갖고 B-ring 또는 C-ring에서 하나의 히드록시기가 치환된 hydroxy-17-hydroxy-Prostanozol로 추정되며 M6은 17번 탄소 위치에 케톤기를 갖고 pyrazole nucleus 혹은 A-ring에 하나의 히드록시기를 또한 B-ring 또는 C-ring에 또 하나의 히드록시기가 치환된 dihydroxy-17-keto-Prostanozol, M7은 M6와 같이 17번 탄소에 케톤기를 갖으며 pyrazole nucleus 혹은 A-ring에 하나의 히드록시기를, 또한 D-ring에 또 하나의 히드록시기를 가진 dihydroxy-17-keto-Prostanozol로 확인되었다. 마지막으로 M8은 pyrazole nucleus 혹은 A-ring에 하나의 히드록시기를 갖고 그 외의 ring에 또 다른 히드록시기가 치환된 dihydroxy-17-hydroxy-Prostanozol임을 확인할 수 있었다. 이중 M5, M7, 그리고 M8은 지금까지 밝혀지지 않았던 새로운 대사체였다. 체내에서의 포합반응 여부를 확인한 결과 Prostanozol과 8종의 모든 대사체가 글루쿠론산 포합체를 형성하였고, 8종의 대사체 중 일부는 포합체를 형성하지 않고도 배출되며 특히 M6과 M7은 황산 포합체로도 배설되는 것을 확인할 수 있었다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제24권4호
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• pp.377-383
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• 2021

Purpose: We investigated the association of effector memory (EM) CD8⁺ T cell and CD4⁺ T cell immunity with metabolic syndrome (MS). Methods: Surface and intracellular staining of peripheral blood mononuclear cells was performed. Anti-interleukin-7 receptor-alpha (IL-7Rα) and CX3CR1 antibodies were used to stain the subsets of EM CD8⁺ T cells, while anti-interferon-gamma (IFN-γ), interleukin-17 (IL-17), and forkhead box P3 (FOXP3) antibodies were used for CD4⁺ T cell subsets. Results: Of the 47 obese children, 11 were female. Children with MS had significantly higher levels of serum insulin (34.8±13.8 vs. 16.4±6.3 µU/mL, p<0.001) and homeostasis model assessment of insulin resistance (8.9±4.1 vs. 3.9±1.5, p<0.001) than children without MS. Children with MS revealed significantly higher frequencies of IL-7Rα^low CD8⁺ T cells (60.1±19.1% vs. 48.4±11.5%, p=0.047) and IL-7Rα^lowCX3CR1⁺ CD8⁺ T cells (53.8±20.1% vs. 41.5±11.9%, p=0.036) than children without MS. As the serum triglyceride levels increased, the frequency of IL-7Rα^lowCX3CR1⁺ and IL-7Rα^highCX3CR1^- CD8⁺ T cells increased and decreased, respectively (r=0.335, p=0.014 and r=-0.350, p=0.010, respectively), in 47 children. However, no CD4⁺ T cell subset parameters were significantly different between children with and without MS. Conclusion: In obese children with MS, the changes in immunity due to changes in EM CD8⁺ T cells might be related to the morbidity of obesity.

• 대한환경공학회지
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• 제32권4호
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• pp.349-356
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• 2010

과염소산이온의 분석을 위해 전기전도도 검출기(CD; conductivity detector)를 연결한 이온크로마토그래피(IC; ion chromatography) 방법이 지금까지 가장 널리 사용되어 왔다. 그러나 이 방법은 시료의 조성에 영향을 받을 수 있고, 정량한계를 낮추는데 한계가 있다. 따라서, 본 연구에서는 미량의 과염소산이온 분석을 위해 이온크로마토그래피 질량분석법(IC-MS/MS; ion chromatography mass spectrometry)을 제시하였다. IC-MS/MS를 이용한 과염소산이온의 분석방법을 적용한 결과 평균회수율 104.4 ${\pm}$ 5.7%, 상대표준편차 1.9 ${\pm}$ 1.3%를 얻었으며, 검출한계(MDL; method detection limit)는 0.0207 ${\pm}$ 0.0099 ${\mu}g/L$를 얻을 수 있었다. IC-MS/MS를 한강수계 지류천과 본류에 적용시킨 결과, 최소 <0.1 ${\mu}g/L$에서 최고 18.30 ${\mu}g/L$ 범위로 나타났다. 서울시 6개 아리수정수센터의 취수원수와 정수에서는 과염소산이온이 0.18~0.34 ${\mu}g/L$의 농도로 존재하는 것으로 나타났다.

• 분석과학
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• 제22권3호
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• pp.210-218
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• 2009

GC-MS/MS를 이용하여 모발 중 암페타민계 마약류 4종과 노르케타민의 동시 분석법을 확립하였으며 결과의 신뢰도를 높이기 위해 분석법 검정을 실시하였다. 모발 시료의 전처리 과정은 증류수와 아세톤을 이용하여 세척, 자동분쇄기를 이용한 세절, 메탄올 용매를 이용한 추출 및 배양 그리고 HFBA로 유도체화하는 단계를 거쳐 GC-MS/MS를 이용하여 분석하였다. 그 결과 모든 분석물질에 대해 정량범위 내에서 우수한 직선성을 나타내었으며, 실제 마약 복용자의 모발감정에 이용될 수 있는 충분한 감도와 선택성, 정밀도와 정확도를 확인하였다. 검정곡선의 결정계수($r^2$)는 0.998 이상을 나타내었고 검출 한계는 0.007 ng/mg 이하였으며 회수율은 75.9-100.9%이었다. 일내 (intra-day) 및 일간 (inter-day) 정확도는 -2.6-17.0%의 범위를 나타내었으며 정밀도는 10.7%이하로 모두 기준값(20% 이하)이내의 값을 나타내었다. 확립된 분석법을 마약 복용자의 모발에 적용한 결과 메스암페타민의 농도 분포는 0.97-19.30 ng/mg이었으며 암페타민은 0.14-2.56 ng/mg이었다.

• 분석과학
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• 제21권3호
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• pp.191-200
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• 2008

의약물질(PPCPs)은 수질 환경 시료에서 새로운 오염물질로 대두되고 있다. 본 연구에서는 LC/ESI-MS/MS를 이용하여 환경 수질 시료로부터 7 종(2-퀴노사린카르복시산, 아세틸살리실산, 디클로페낙-소듐, 나프록센, 이부프로펜, 메페남산, 탈니플루메이트)의 산성의약물질을 동시 분석하는 방법을 비교하여 개선하였으며 폐수처리장의 유입수 및 방류수 그리고 연장선상의 하천수의 오염도를 측정하였다. LC/ESI-MS/MS 분석을 위해서 MCX (Mixed Cation eXchange) 카트리지와 HLB (Hydrophilic-Lipophilic Balance) 카트리지를 연결하는 텐뎀 고체상 추출법과 MCX 카트리지만을 사용하는 고체상 추출법을 이용하여 효과적인 시료 정제 및 추출을 수행하였다. 검출한계(LODs)와 방법검출한계(MDLs)는 각각 0.05~1.50 pg/mL, 0.17~4.90 pg/mL 범위를나타내었다. 시료중 1.0 ng/mL 농도(n=3)에서절대회수율은 81.9%~116.3%를 나타내었다. 수질 환경 시료에서 수 pg/mL~ng/mL의 농도로 산성의약물질이 측정되었다.

• Advances in concrete construction
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• 제3권4호
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• pp.317-331
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• 2015

This paper presents the effect of different micro-silica (MS) contents of 5, 10 and 15 wt.% as partial replacement of cement on mechanical and durability properties of high volume fly ash - recycled aggregate concretes (HVFA-RAC) containing 50% class F fly ash (FA) and 35% recycled coarse aggregate (RCA) as partial replacement of cement and natural coarse aggregate (NCA), respectively. The measured mechanical and durability properties are compressive strength, indirect tensile strength, elastic modulus, drying shrinkage, water sorptivity and chloride permeability. The effects of different curing ages of 7, 28, 56 and 91 days on above properties are also considered in this study. The results show that the addition of MS up to 10% improved the early age (7 days) strength properties of HVFA-RAC, however, at later ages (e.g. 28-91 days) the above mechanical properties are improved for all MS contents. The 5% MS exhibited the best performance among all MS contents for all mechanical properties of HVFA-RAC. In the case of measured durability properties, mix results are obtained, where 10% and 5% MS exhibited the lowest sorptivity and drying shrinkage, respectively at all ages. However, in the case of chloride ion permeability a decreasing trend is observed with increase in MS contents and curing ages. Strong correlations of indirect tensile strength and modulus of elasticity with square root of compressive strength are also observed in HVFA-RAC. Nevertheless, it is established in this study that MS contributes to the sustainability of HVFA-RAC significantly by improving the mechanical and durability properties of concrete containing 50%less cement and 35% less natural coarse aggregates.

• Journal of Pharmaceutical Investigation
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• 제37권3호
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• pp.179-186
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• 2007

A simple, sensitive and selective liquid chromatographic/tandem mass spectrometric method (LC-MS/MS) was developed and validated for doxifluridine and 5-fluorouracil (5-FU) quantification in dog heparinized plasma. Sample preparation was based on liquid-liquid extraction using a mixture of isopropanol/ethyl acetate (1/9 v/v) to extract doxifluridine, 5-FU and 5-chlorouracil (5-CU, an internal standard) from plasma. Chromatography was performed on a C-18 analytical column and the retention times were 2.7, 1.5 and 1.7 min for doxifluridine, 5-FU and 5-CU, respectively with shorter analysis time within 5 min than previously reported methods. The ionization was optimized using ESI negative mode and selectivity was achieved by tandem mass spectrometric analysis by multiple reaction monitoring (MRM) using the transformations of m/z 244.8>107.6, 129.0>42.0 and 144.9>42.1 for doxifluridine, 5-FU and 5-CU, respectively. The achieved low limit of quantification was 20.0 ng/mL and the assay exhibited linear range of 20-2000 ng/mL ($R^2>0.99957$ for doxifluridine and $R^2>0.99857$ for 5-FU), using $100{\mu}L$ of plasma. Accuracy and precision of quality control samples for both doxifluridine and 5-FU met KFDA and FDA Guidance criteria of 15% for accuracy with coefficients of variation less than 15%. This method demonstrated adequate sensitivity, specificity, accuracy, precision and stability to support the simultaneous analysis of doxifluridine and 5-FU in dog plasma samples in pharmacokinetic and bioequivalence studies.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2010년도 정기총회 및 춘계학술발표회
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• pp.18-18
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• 2010

Glucosinolates(GSLs) are major secondary products($\beta$-thioglucoside N-hydroxysulfates) containing sulfates that are found mainly in Cruciferae family such as cabbage, broccoli, radish, turnip, kale, mustard and rapeseed as the important crops in agronomic and economic aspects. Especially, isothiocyanates(ITCs) have been shown to inhibit carcinogenesis with regulation cancer cell development followed by regulating target enzymes, inducing cell cycle arrest and apoptosis against various human cancer cell lines. Total desulfo(DS)-GSLs of nine type in 210 Korean leaf mustard accessions were isolated and confirmed using electrospray ionization mass spectrometric(ESI-MS/MS) method and DS-GSLs powerful library maked from several reference data. The isolated individual DS-GSLs were identified by removed $\beta$-D-glucopyranose residue ($C_6H_{11}O_5$, MW 163) from MS/MS data. Among them sinigrin(41.7%), glucoiberverin(21.7%) and gluconasturtiin(12.6%) were major components, Especially, despite gluconapin was minor component, accession K046197-1 and K046197-2 showed higher content of 4.11 and 3.31 mg/g(DW), respectively. The total GSLs contents in 210 accessions were ranged from 5.3 to 23.2 mg/g(DW) with a mean value of 13.0 mg/g(DW). As a result of principal component analysis(PCA), the individual GSLs loading plots were composed of three groups and components belonged to each group showed correlationship in quantitative pattern.

• 한국동물위생학회지
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• 제30권1호
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• pp.13-21
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• 2007

An atmospheric pressure chemical ionization (APcI) LC/MS/MS method was developed for the simultaneous analysis of fluoroquinolones (norfloxacin, ciprofloxacin, enrofloxacin, danofloxacin) residues in eggs. The spiked and blank samples were extracted from whole eggs using 50mM phosphate buffer (pH 7.4). The extract was cleaned up by passage though $Oasis^{(R)}$ MAX extraction cartridge for solid-phase extraction followed by elution with 4% formic acid in methanol. The extract of sample was separated on a Waters $Atlantis^{TM}$ $dC_{18}$ reversed-phase column ($4.6{\times}150mm,\;5{\mu}m$) and analyzed by APcI positive mode mass spectrometry. The mobile phase consists of aqueous 0.2% nonafluoropentanoic acid (NFPA) and methanol. Multiple reaction monitoring (MRM) using the precursor to product ion combinations of m/z $320\;{\dashrightarrow}\;302,\;332\;{\dashrightarrow}\;314,\;360\;{\dashrightarrow}\;342$ and m/z $358\;{\dashrightarrow}\;340$ were used to quantify norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR) and danofloxacin (DAN), respectively. The limits of quantification (LOQ) were 7.8ppb for NOR, 8.5ppb for CIP, 8.9ppb for ENR, and 4.8ppb for DAN. Average recoveries of fortified sample at levels of 0.025 to 0.1 ppm were estimated 71.29% for NOR, 75.27% for CIP, 85.51% for ENR and 81.22% for DAN. These results could be applied for the confirmation and quantification in eggs.