• Bulletin of the Korean Chemical Society
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• 제27권7호
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• pp.1048-1052
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• 2006

Ab initio calculations of the structure, atomic charges and natural bond orbital (NBO) have been performed at HF/6-311G** and B3LYP/6-311G** levels for the title compound of dibenzothiazyl-disulfide. The calculated results show that the two nitrogen atoms have the biggest negative charges and they are the potential sites to react with the metallic ions, which make the title compound become a di-dentate ligand. Vibrational frequencies of the title compound have been obtained and compared with the experimental value and the comparison indicates that B3LYP/6-311G** level is better than HF/6-311G** level to predict the vibrational frequencies for the system studied here. For the title compound, electronic absorption spectra calculated by time?ependent density functional theory (TD-DFT) are more accurate than Hartree-Focksingle-excitation CI (CI-Singles) method. NBO analyses show that the electronic transitions are mainly derived from the contribution of bands $\pi\rightarrow\pi^{*}$. Thermodynamic calculated results show that the formation of the title compound from 2-mercaptobenzothiazole is a spontaneous process at room temperature with the change of free Gibbs being negative value.

• Journal of Radiation Protection and Research
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• 제18권1호
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• pp.37-51
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• 1993

본 연구에서는 환기장치로 제어하는 환경인 라돈 표준실 및 라돈 발생기로부터 이론적으로는 Jacobi모델 이론을 사용하여 라돈 자핵종의 농도를 계산하였으며, 실험적으로는 두 발생 조건으로부터 채취된 시료를 알파스펙트럼 분석법에 의해 측정 분석하여 그 농도를 결정하였다. 이론적인 계산치와 실험적인 측정결과를 비교해 본 결과 매우 잘 일치되는 좋은 결과를 얻게 되었다. 따라서 이러한 연구는 실내 라돈환경에서 라돈 자핵종의 알파방출체에 의한 내부피폭선량을 보다 정확히 평가하고, 라돈 자핵종의 개별 농도를 신속히 결정하는 데 크게 기여할 것이라 사료된다.

• 동의신경정신과학회지
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• 제3권1호
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• pp.56-59
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• 1992

The zinc, copper and chromium contents in the hair in 103 healthy Korean and 126 Korean with schizophrenic(aged 20 to 59 years in Yanbian district)by atomic absorbtion spectrometer(Type WFZ-II). Research Period : from May 1985 to September 1986. The zinc, copper and chromium contents in the schizophrenic hair are significantly lower than those of healthy persons, respectively. The standard rates of discriminant from healthy persons and the patients by method of (Department of Pathophysiology, Yanbian Medical Colloge ; Yanbian Neuropsychosis Hospital, Yanji Jilin Prov, P.R. China) Fisher discrominant analysis are 72.9% and 84.4%, respectively. The rates of the contribution of the target for the functional equation of zinc, copper chromium are 12.3%, 5.9% and 81.8%, respectively. Zinc contents in hair of male patients are significantly higher than those of female patients ; copper contents in hair of the female are sign

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.233-240
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• 1996

Analyses of the viscous and end effects on electromagnetic (EM) pumps of annular linear induction type for the sodium coolant circulation in Liquid Metal Fast Breeder Reactors have been carried out based on the MHD laminar flow analysis and the electromagnetic field theory. A one-dimensional MHD analysis for the liquid metal flowing through an annular channel has been performed on the basis of a simplified model of equivalent current sheets instead of three-phase currents in the discrete primary windings. The calculations show that the developed pressure difference resulted from electromagnetic and viscous forces in the liquid metal is expressed in terms of the slip, and that the viscous loss effects are negligible compared with electromagnetic driving forces except in the low-slip region where the pumps operate with very high flow velocities comparable with the synchronous velocity of the electromagnetic fields, which is not applicable to the practical EM pumps. A two-dimensional electromagnetic field analysis based on an equivalent current sheet model has found the vector potentials in closed form by means of the Fourier transform method. The resultant magnetic fields and driving forces exerted on the liquid metal reveal that the end effects due to finiteness of the pump length are formidable. In addition, a two-dimensional numerical analysis for vector potentials has been performed by the SOR iterative method on a realistic EM pump model with discretely-distributed currents in the primary windings. The numerical computations for the distributions of magnetic fields and developed pressure differences along the pump axial length also show considerable end effects at both inlet and outlet ends, especially at high flow velocities. Calculations of each magnetic force contribution indicate that the end effects are originated from the magnetic force caused by the induced current ( u x B ) generated by the liquid metal movement across the magnetic field rather than the one (E) produced by externally applied magnetic fields by three-phase winding currents. It is concluded that since the influences of the end effects in addition to viscous losses are extensive particularly in high-velocity operations of the EM pumps, it is necessary to find ways to suppress them, such as proper selection of the pump parameters and compensation of the end effects.

• 한국수산과학회지
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• 제50권6호
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• pp.675-683
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• 2017

Total mercury (T-Hg) and methyl mercury (MeHg) were determined in marine fisheries (41 species, n=87) commonly consumed in Korea, using a gold amalgamation method and gas chromatography-cold vapor atomic fluorescent spectroscopy, respectively. Concentrations of T-Hg and MeHg in all samples (31 fish, 4 crustaceans, 4 cephalopods, and 2 gastropod species) were in the range of 0.016-0.495 (mean, 0.093) mg/kg-wet and not detected-0.338 (mean, 0.067) mg/kg-wet, respectively. The concentrations of MeHg in marine fisheries were significantly correlated with T-Hg concentrations (P<0.001). The highest mean concentrations of T-Hg and MeHg were found in fish species, followed by crustaceans. The contribution of MeHg to T-Hg was in the range of 64-95% (mean, 83%) in cephalopods, 28-98% (mean, 69%) in fish, and 26-88% (mean, 57%) in crustaceans. The weekly intakes of T-Hg and MeHg by fisheries consumption for the Korean general population were estimated to be 0.463 and $0.338{\mu}g/kg$ body weight/week, respectively. The concentrations and intakes of T-Hg and MeHg were less than the allowable residue levels and in the range of 12 to 17% of the provisional tolerable weekly intake (PTWI) applied in Korea.

• 방사성폐기물학회지
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• 제15권1호
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• pp.35-44
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• 2017

감마분광분석 시스템 상에서는 $^{226}Ra$(186.2 keV)과 $^{235}U$(185.7 keV)가 방출하는 감마선 에너지의 피크 중첩이 발생한다. $^{226}Ra$의 직접분석을 위해서는 중첩된 피크로부터 $^{235}U$의 기여를 제거해주거나 보정상수를 이용하여 실제 $^{226}Ra$의 방사능 값으로 보정 해주어야 한다. $^{235}U$가 방출하는 다른 감마선 피크를 참조하여 $^{235}U$의 기여를 제거할 경우 복잡한 수계산이 필요하며, 참조피크에서 기인하는 큰 불확도로 인해 높은 정량한계를 갖는다. 반면에 보정상수를 이용하여 $^{226}Ra$을 평가할 경우 간단한 계산으로 평가가 가능하며, 간접측정시 요구되는 $^{222}Rn$의 용기건전성과 방사평형 복구기간이 필요하지 않아 $^{226}Ra$의 신속 측정시 유용한 방법이다. 따라서 해당 방법을 통해 원료물질 3종과 공정부산물 3종, 총 93여개 시료에 대해서 보정상수로 산출된 $^{226}Ra$의 방사능 농도와 방사평형 된 $^{214}Bi$의 방사능 농도의 비교를 통해 유효성을 확인하였다. 대부분 ${\pm}20%$ 내에서 유효하였지만 인산석고의 경우 약 50%의 오차를 보였다. 이는 보정상수를 유도하기 위한 가정 중 $^{238}U$과 $^{226}Ra$의 방사평형 관계가 달라진 것으로 판단된다. 특이성을 반영한 보정상수를 적용하여 $^{226}Ra$의 방사능 농도에 대한 유효성을 평가한 결과 약 ${\pm}10%$로 좀 더 정밀한 결과를 얻을 수 있었다. 본 연구에서 산출된 보정상수를 통한 $^{226}Ra$의 방사능 농도 평가 방법은 복잡한 수계산이 필요하지 않고 용기선택으로부터 자유로우며 방사평형 복구를 위한 기간이 필요하지 않아 원료물질 및 공정부산물의 $^{226}Ra$의 신속한 농도 분포 평가시 유효한 방법이다.

• Nuclear Engineering and Technology
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• 제45권4호
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• pp.513-522
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• 2013

The ODSCC detected in the TSP position of Ulchin 3&4 SGs are typical ODSCC of Alloy 600MA tubes. The causative chemical environment is formed by concentration of impurities inside the occluded region formed by the tube surface, egg crate strips, and sludge deposit there. Most cracks are detected at or near the line contacts between the tube surface and the egg crate strips. The region of dense crack population, as defined as between $4^{th}$ and $9^{th}$ TSPs, and near the center of hot leg hemisphere plane, coincided well with the region of preferential sludge deposition as defined by thermal hydraulics calculation using SGAP computer code. The cracks developed homogeneously in a wide range of SGs, so that the number of cracks detected each outage increased very rapidly since the first detection in the $8^{th}$ refueling outage. The root cause assessment focused on investigation of the difference in microstructure and manufacturing residual stress in order to reveal the cause of different susceptibilities to ODSCC among identical six units. The manufacturing residual stress as measured by XRD on OD surface and by split tube method indicated that the high residual stress of Alloy 600MA tube played a critical role in developing ODSCC. The level of residual stress showed substantial variations among the six units depending on details of straightening and OD grinding processes. Youngwang 3&4 tubes are less susceptible to ODSCC than U3 and U4 tubes because semi-continuous coarse chromium carbides are formed along the grain boundary of Y3&4 tubes, while there are finer less continuous chromium carbides in U3 and U4. The different carbide morphology is caused by the difference in cooling rate after mill anneal. There is a possibility that high chromium content in the Y3&4 tubes, still within the allowable range of Alloy 600, has made some contribution to the improved resistance to ODSCC. It is anticipated that ODSCC in Y5&6 SGs will be retarded more considerably than U3 SGs since the manufacturing residual stress in Y5&6 tubes is substantially lower than in U3 tubes, while the microstructure is similar with each other.

• 대한지역사회영양학회지
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• 제28권3호
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• pp.235-244
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• 2023

Objectives: Based on the results from the Korean Total Diet Study (KTDS), the sodium (Na) and potassium (K) intake of Koreans were estimated and compared with intake estimates from the Food & Nutrient Database (FNDB), as in the Korea National Health and Nutrition Examination Survey (KNHANES) to verify the validity of these estimates. Methods: One hundred and thirty-four representative foods (RFs) covering 92.5% of the total food intake of Koreans were selected, and 228 pairs of corresponding 'RF x representative cooking method' were derived by reflecting the methods used mainly in terms of frequency and quantity in their cooking. RF samples were collected from three cities with a larger population size in three regions (nine cities) nationwide, and six composite samples were made for each RF, considering its regional and/or seasonal characteristics. One thousand three hundred and sixty-eight 'RF x representative cooking method' pair samples were prepared, and the Na and K contents were assessed using inductively coupled plasma atomic emission spectrometry (ICP-MS). The Na and K intake of the Korean population was estimated by linking the content with the food intake data from the 7th KNHANES. Results: The mean Na and K intake of Koreans were 2,807.4 mg and 2,335.0 mg per person per day, respectively. A comparison with the Na and K intake from KNHANES, including only RFs of KTDS, showed comparable results with less than 5% variation. While the contribution and ranking of food items to Na intake were similar between KNHANES and KTDS, there were differences in K intake. This was attributed to the large discrepancies in the K content of rice and coffee between KTDS results and the values in the 9th Revision of the National Food Composition Table used in KNHANES. Conclusions: The Na and K intake of Koreans estimated based on the KTDS, which performed nutrient analysis on samples prepared to a 'table-ready' state using foods of the representative collection, was similar and comparable with that of KNHANES. This supports the validity and usefulness of FNDB-based nutrient intake estimation at the population level. The list of nutrients studied in KTDS is expected to be expanded, allowing for intake estimation of nutrients with currently insufficient or absent information in the FNDBs in use.