• 한국대기환경학회지
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• 제24권5호
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• pp.562-573
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• 2008

Concentrations of volatile organic compounds (VOCs) measured from the local industrial sources in Wanju industrial complex during June $2007{\sim}January$ 2008. The samples were collected from the primary sources (6 emission points) in 4 major factories in Wanju industrial complex as well as two general sources in Wanju County to elucidate the abundances of speciated VOCs and their spacial and temporal distributions depending on source bases. Industrial sources are as follows; fabricated metal manufacture, motor vehicle manufacture, rubber and plastic manufacture, and chemical manufacture factories. Two general source samples were collected from gasoline gas station and dry cleaning shop in urban area. In order to understand the near source influence at receptor, samples from the two receptor sites (one is at center of the industrial complex and the other site is at distance residential area downwind from the center) were collected with sample canister, and analyzed by using GC/MSD. The concentrations from different sources were compared and discussed. The mass contributions of the speciated VOCs to total VOCs measured from industrial sources and ambient ai r at two receptors were presented and discussed.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.114-122
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• 2024

Irradiation-induced defects and the precipitates in the wrapper material of the Indian Fast Breeder Test Reactor (FBTR), SS 316 are analyzed using the synchrotron source-based Angle Dispersive X-Ray Diffraction (ADXRD) technique with X-rays of energy 17.185 keV (wavelength ~0.72146 Å). The differences and similarities in the high displacement damage samples as a function of dpa (displacement per atom) and dpa rate in the range of 2.9 × 10^-7- 9 × 10^-7 dpa/s are studied. Ferrite and M₂₃C₆ are commonly observed in the present set of high displacement damage 40-74 dpa SS 316 samples irradiated at temperatures in the range of 400-483 ℃. Also, the dislocation density has increased as a function of the irradiation dose. The X-ray diffraction peak profile parameters quantified such as peak shift and asymmetry show that the irradiation-induced defects are sensitive to the dpa rate-irradiation temperature combinations. The increase in yield strength as a function of displacement damage is also correlated to the dislocation density.

• 한국대기환경학회지
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• 제26권6호
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• pp.633-648
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• 2010

The study was performed to elucidate the characteristics of VOCs at distinct monitoring sites in urban atmosphere; one is at a roadside in downtown inland city of Jeonju, and the other is at an industrial site in Gunsan near coastal area. The ambient samples were collected for 24 hours in two-bed adsorbent tubes by using MTS-32 sequential tube sampler equipped with Flex air pump every 16 days in a roadside and a industrial complex from February to November in 2009. VOCs were determined by thermal desorption coupled with GC/MSD. Major individual VOCs in roadside samples were shown as following order in magnitude: toluene>m,p-xylene>ethyl benzene>decanal; and those in the industrial complex samples were as follows: toluene>ethanol>ethyl acetate>decanal>m,pxylene. High benzene concentration in the roadside was more frequently occurred than in the industrial complex. However ambient level of toluene in the industrial complex was higher than that in the road side. Results from roadside sample analysis showed that nonane and 1,2,4-trimethylbenzene were very frequently observed with higher concentrations than those in the industrial complex. It seems that nonane and 1,2,4-trimethylbenzene could be the source characteristics for the roadside air. From the diurnal variation, it was found that concentrations of benzene, ethylbenzene, xylene, nonane and 1,2,4-trimethylbenznene in the roadside were higher during rush hours; but those in the industrial complex were higher from 10 to 16 LST when the industrial activities were animated. On weekly base, the concentration of benzene, toluene, ethylbenzene and m,p-xylene in the roadside were higher specifically on Wednesday, but those in the industrial complex were higher on Sunday. It was found that the general trends of VOCs levels at both sites significantly influence on seasonal changes. The results of factor analysis showed that the VOCs in the roadside were mainly affected by the emission of vehicles and the evaporation of diesel fuel, meanwhile those in the industrial complex were influenced by the evaporation of solvents and vehicular emission.

• 한국세라믹학회지
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• 제31권9호
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• pp.1012-1220
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• 1994

BaTiO3 ceramics doped with 0.1 to 4.0 mol% Nb2O5 were prepared by conventional solid stage sintering process, so as to investigate the effect of the amount of Nb2O5 on the dielectric properties and complex impedance patterns of barium titanates. From the measurement of capacitance, we found that the dielectric constant of BaTiO3 samples with 1 mol% or more Nb2O5 remained approximately constant around room temperature with values higher than 2500. In this paper, the effect of impurity content as well as temperature on complex impedance patterns was discussed in detail. In particular, the grain and grain boundary behavior of samples which showed PTCR characteristics was discussed in terms of measuring temperature.

• 분석과학
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• 제32권1호
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• pp.24-34
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• 2019

The safety of food is occasionally questionable, as there have been some reports of products contaminated with illegal adulterants. In this study, the presence of 16 sedative-hypnotics and sleep inducers in dietary supplements was determined by ultra-high-performance liquid chromatography with UV detection (UPLC-UV) and quadruple Orbitrap mass spectrometry (Q-Orbitrap-MS). The UPLC method was validated, providing a linearity (R2) of more than 0.999, and LODs and LOQs that ranged from 0.2 to 0.5 and 0.6 to $1.5{\mu}g\;mL^{-1}$, respectively. The repeatabilities were 0.2-8.4 % (intra-day) and 0.3-4.5 % (inter-day), and the accuracies were 89.0-117.0 % (intra-day) and 87.8-111.9 % (inter-day). The mean recoveries of the spiked samples ranged from 98.7 to 107.3 %. The relative standard deviation (%RSD) of the stability was less than 2.4 %. Using the developed method, one sedative-hypnotic compound, phenobarbital, was detected in one of the nineteen samples tested. In addition, the major characteristic fragment ions of each target compound were confirmed using Q-Orbitrap-MS for higher accuracy. Monitoring the presence of these 16 sedative-hypnotics and sleep inducers in dietary supplements should be pursued in the interest of human health, and the results of this study confirmed that the developed method has value for this application.

• 분석과학
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• 제36권1호
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• pp.1-11
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• 2023

A new, sensitive, and reliable flow injection methodology was investigated for the determination of lead ion (II) in vegetables' samples using a laboratory-prepared reagent 2-[(6-methoxy-2-benzothiazoly)azo]-4-methoxy phenol (6-MBTAMP). Infrared spectroscopy, UV-visible spectrophotometry, Energy dispersive X-ray spectroscopy (EDX), Elemental Analysis (CHN), nuclear magnetic resonance spectroscopy ¹HNMR, and ¹³CNMR techniques were used to characterize the reagent and lead (II) complex. The method is based on lead ion (II) reacting with the reagent (6-MBTAMP) in a neutral solution to produce a green-red complex with a maximum absorbance at 670 nm. The optimum conditions, such as flow rate, lead ion (II) volume, reagent volume, medium pH, reagent concentration, and reaction coil length were thoroughly examined. The limits of detection (LOD) and quantification (LOQ) were determined to be 0.621 mg·L^-1 and 2.069 mg·L^-1 , respectively, while Sandell's sensitivity was determined to be 0.345 ㎍·cm^-2.

• Genomics & Informatics
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• 제6권1호
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• pp.18-28
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• 2008

Single nucleotide polymorphisms (SNPs) are the most abundant forms of human genetic variations and resources for mapping complex genetic traits and disease association studies. We have constructed a linkage disequilibrium (LD) map of chromosome 22 in Korean samples and compared it with those of other populations, including Yorubans in Ibadan, Nigeria (YRI), Centre d'Etude du Polymorphisme Humain (CEPH) reference families (CEU), Japanese in Tokyo (JPT) and Han Chinese in Beijing (CHB) in the HapMap database. We genotyped 4681 of 111,448 publicly available SNPs in 90 unrelated Koreans. Among genotyped SNPs, 4167 were polymorphic. Three hundred and five LD blocks were constructed to make up 18.6% (6.4 of 34.5 Mb) of chromosome 22 with 757 tagSNPs and 815 haplotypes (frequency $\geq$ 5.0%). Of 3430 common SNPs genotyped in all five populations, 514 were monomorphic in Koreans. The CHB + JPT samples have more than a 72% overlap with the monomorphic SNPs in Koreans, while the CEU + YRI samples have less than a 38% overlap. The patterns of hot spots and LD blocks were dispersed throughout chromosome 22, with some common blocks among populations, highly concordant between the three Asian samples. Analysis of the distribution of chimpanzee-derived allele frequency (DAF), a measure of genetic differentiation, Fst levels, and allele frequency difference (AFD) among Koreans and the HapMap samples showed a strong correlation between the Asians, while the CEU and YRI samples showed a very weak correlation with Korean samples. Relative distance as a quantitative measurement based upon DAF, Fst, and AFD indicated that all three Asian samples are very proximate, while CEU and YRI are significantly remote from the Asian samples. Comparative genome-wide LD studies provide useful information on the association studies of complex diseases.

• 분석과학
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• 제32권2호
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• pp.35-47
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• 2019

In this study, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was employed to detect 26 antidiabetic compounds in adulterated dietary supplements using a simple, selective method. The work presented herein may help prevent incidents related to food adulteration and restrict the illegal food market. The best separation was obtained on a Shiseido Capcell Pak(R) C18 MG-II ($2.0mm{\times}100mm$, $3{\mu}m$), which improved the peak shape and MS detection sensitivity of the target compounds. A gradient elution system composed of 0.1 % (v/v) formic acid in distilled water and methanol at a flow rate of 0.3 mL/min for 18 min was utilized. A triple quadrupole mass spectrometer with an electrospray ionization source operated in the positive or negative mode was employed as the detector. The developed method was validated as follows: specificity was confirmed in the multiple reaction monitoring mode using the precursor and product ion pairs. For solid samples, LOD ranged from 0.16 to 20.00 ng/mL and LOQ ranged from 0.50 to 60.00 ng/mL, and for liquid samples, LOD ranged from 0.16 to 20.00 ng/mL and LOQ ranged from 0.50 to 60.00 ng/mL. Satisfactory linearity was obtained from calibration curves, with $R^2$ > 0.99. Both intra and inter-day precision were less than 13.19 %. Accuracies ranged from 80.69 to 118.81 % (intra/inter-day), with a stability of less than 14.88 %. Mean recovery was found to be 80.6-119.0 % and less than 13.4 % RSD. Using the validated method, glibenclamide and pioglitazone were simultaneously determined in one capsule at concentrations of 1.52 and 0.53 mg (per capsule), respectively.

• 한국치위생학회지
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• 제18권3호
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• pp.347-358
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• 2018

Objectives: The purpose of this study is to identify the association between oral health status and pulmonary ventilatory defects. Methods: The 6th (2013-2015) National Health and Nutrition Examination Survey data was used. The study subjects were those aged 40-79 who had pulmonary function examination. Complex samples general linear model analysis, Complex samples cross-tabulation analysis, and Complex samples logistic regression analysis were conducted. Results: In terms of restrictive ventilatory defects, the study subjects (8.3%) who recognized that their oral health status was bad outnumbered those who recognized that their oral health status was good (6.1%) (p<0.05). Many of the study subjects who experienced difficulty in biting, chewing and/or speech, and who had an unhealthy periodontal had restrictive ventilatory defects and obstructive ventilatory defects (p<0.05). The association between oral health status and pulmonary ventilatory defects was analyzed. The findings showed that those who had unhealthy periodontal had a 1.33 times higher probability of pulmonary ventilatory defects than those who had a healthy periodontal (p<0.05). After taking into account general characteristics (age, sex, incomes, education, and smoking) of the subjects, the association between oral health status and pulmonary ventilatory defects was analyzed. The result found that only in cases where one experienced dental caries was an association with pulmonary ventilatory defects found. In other words, those who had dental caries showed a 0.73 times higher probability of pulmonary ventilatory defects than those who had no dental caries (p<0.05). Conclusions: Based on the findings of this research, oral health status was found to be associated with pulmonary ventilatory defects. To improve oral health, it is necessary to provide life-cycle stages based oral health education. Therefore, it is required to develop an oral health education program and develop a national oral health policy.

• 대한방사성의약품학회지
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• 제6권1호
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• pp.20-26
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• 2020

Accelerator mass spectrometry (AMS) is a powerful detection technique with the exquisite sensitivity and high precision compared with other traditional analytical techniques. Accelerator mass spectrometry can be widely applied in the technique of radiocarbon dating in the fields of archeology, geology and oceanography. The ability of accelerator mass spectrometry to measure rare ¹⁴C concentrations in microgram and even sub-microgram amounts suggests that extension of ¹⁴C-accelerator mass spectrometry to biomedical field is a natural and attractive application of the technology. Drug development processes are costly, risky, and time consuming. However, the use of ¹⁴C-accelerator mass spectrometry allows absorption, distribution, metabolism and excretion (ADME) studies easier to understand pharmacokinetics of drug candidates. Over the last few decades, accelerator mass spectrometry and its applications to preclinical/clinical trials have significantly increased. For accelerator mass spectrometry analysis of biological samples, graphitization processes of samples are important. In this paper, we present a detailed sample preparation procedure to apply to graphitization of biological samples for accelerator mass spectrometry.