• Analytical Science and Technology
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• v.27 no.6
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• pp.269-276
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• 2014

A short study for the uncertainty of post column isotope dilution method has been performed for the analysis of Selenomethionine in HPLC-ICP/MS. Major error sources studied were concentration and the flow rate of Se isotope solution, atomic weights of Se in spike and sample, and isotope ratio measured for the spiked sample. Uncertainties were obtained for each factor and the contribution for the total concentration uncertainty was 54.4% and 0.61%, 0.0072% and 0.018%, and 45.0%, respectively. The biggest contribution factor was concentration of the spike solution and the second was the isotopic ratio measured for the spiked sample solution. The mass flow rate of spike and atomic weights did not show much contribution. The calculated total uncertainty was $1.46ng{\cdot}g^{-1}$ for the standard SeMet ($126.30ng{\cdot}g^{-1}$). The experimental result was $127.09{\pm}1.46ng{\cdot}g^{-1}$ and the relative uncertainty was 1.20%.

• Nuclear Engineering and Technology
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• v.50 no.1
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• pp.140-144
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• 2018

Isotopic analyses of plutonium and low-enriched uranium mixtures with particle sizes of $0.6-3.3{\mu}m$ were performed using thermal ionization mass spectrometry with a continuous heating method to verify its effectiveness for the accurate analysis of minor isotopes without sample pretreatment. The mixed particles used in this study were prepared from a mixed solution of plutonium (SRM 947) and uranium (U010, $^{235}U$ 1% enriched) reference materials. The isotope ratios for plutonium in the individual mixed particles, including $^{238}Pu/^{239}Pu$, $^{241}Pu/^{239}Pu$ as well as $^{240}Pu/^{239}Pu$, and $^{242}Pu/^{239}Pu$, were in good agreement with the certified values despite the isobaric interference of $^{238}U$ and $^{241}Am$. The isotope ratios for uranium in the mixed particles also agreed well with the certified values within the range of error. However, the isotope ratios for minor isotopes, such as $^{234}U$ and $^{236}U$, in the particles with diameters of less than approximately $1.8{\mu}m$ could not be measured because numbers of $^{234}U$ and $^{236}U$ atoms in analyzed particles are too low. These results indicate that thermal ionization mass spectrometry with a continuous heating method is applicable for the analysis of trace amounts of plutonium isotopes, including $^{238}Pu$ and $^{241}Pu$, despite the presence of the respective isobars $^{238}U$ and $^{241}Am$ in the microsamples.

• Tunnel and Underground Space
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• v.17 no.2 s.67
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• pp.119-127
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• 2007

Based on the critical plane approach, a methodology far predicting the anisotropic strength ot transversely isotropic rock is Proposed. It is assumed that the rock failure is governed by Hoek-Brown failure criterion. In order to establish an anisotropic failure function, Mohr envelope equivalent to the original Hoek-Brown criterion is used and the strength parameters m, s are expressed as scalar functions of orientation. The conjugate gradient method, which is one of the robust optimization techniques, is applied to the failure function for searching the orientation giving the maximum value of the anisotropic function. While most of the existing anisotropic strength models can be applied only when the stress condition is the same as that of conventional triaxial compression test, the proposed model can be applied to the general 3-dimensional stress conditions. Through the simulation of triaxial compression tests for transversely isotropic rock sample, the validity of the proposed method is investigated by comparing the predicted triaxial strengths and inclinations of failure plane.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.557-564
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• 2023

Nuclear materials such as uranium are used as fuel for nuclear power generation, but there is a high possibility that they will be used for non-peaceful purposes, so international inspections and regulations are being conducted. Isotope analysis data of fine particulate obtained from nuclear facilities can provide important information on the origin and concentration method of nuclear material, so it is widely used in the field of nuclear safety and nuclear forensics. In this study we describe the analytical method that can directly identify nuclear particles and measure their isotopic ratios for fine samples using a large-geometry secondary ion mass spectrometer and introduce its preliminary results. Using the U-200 standard material, the location of fine particles was identified and the results consistent with the standard value were obtained through microbeam analysis.

• The Journal of the Petrological Society of Korea
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• v.24 no.4
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• pp.365-371
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• 2015

The rare earth element(REE)s play an important role in understanding of rock formation and evolution because of their similar geochemical behaviors. Sm and Nd are more useful than other REEs because Sm-Nd isotopic system has important applications for geochemical interpretation like age dating and crustal evolution. These studies require a chromatographic technique for Sm and Nd separation from the geological samples. Ln-resin method using 0.25 M HCl as the eluent is widely used for Nd separation. However, this technique has a disadvantage of the poor elemental selectivity that the Nd fraction contains Ce as a tailing of the previous fraction. This technical report is a comparison study on the effect of eluent concentration between 0.25 M HCl and 0.15 M HCl on the separation of Nd with Ln-resin method for improving the technique of Nd separation. The results showed that the separation of Ce and Nd using 0.15M HCl as the eluent was not effective compared to the separation using 0.25 M HCl. In this experiment, we could confirm that the dilution of eluent might not be effective on the high purity separation of Nd with Ln-resin method.

• Analytical Science and Technology
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• v.25 no.2
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• pp.146-151
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• 2012

An analytical method was developed for the measurement of uranium isotope in ground water using the liquid scintillation counting technique. A LKB Wallac Quantulus 1220 liquid scintillation counter (LSC) equipped with pulse shape analyzer (PSA) and a solvent extraction method were used for the measurement of uranium isotope in ground water samples. The effect of solution volume on the extraction efficiency was evaluated for 100 to 1000 mL solutions using a NIST standard reference material (NIST SRM 4321C). The effect of groundwater pH on the extraction efficiency was also investigated for pH ranging from 0.5 to 10. It was found that the extraction efficiency had a strong dependence on pH showing a maximum at pH 2. In contrast, the effect of groundwater volume on the extraction efficiency was negligible in the range investigated. According to the method, the extraction efficiency of uranium isotopes was near 96% and the lower detection limit for uranium was 0.018 Bq/L with the counting time of 300 min. The result of this study was also verified by the conventional ICP-MS measurement. It is demonstrated that the suggested method is valuable to the determination of the optimum extraction and measurement conditions for uranium in ground water. The method was successfully applied to the ground water at four locations near the Daejeon province. It was found that the uranium content and the isotopic ratio of $^{234}U/^{238}U$ at the locations ranged 0.59~6.69 Bq/L and 0.72~1.40, respectively.

• The Journal of Engineering Geology
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• v.30 no.3
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• pp.303-314
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• 2020

Bottled water companies submit monthly hydrologic data including periodical environmental effects investigation, daily water production capacity, water production, water level, water chemistry (pH, EC, temperature) per hour and strictly manage groundwater by periodical analyses. Thus few problems concerning drawdown due to excess intake of groundwater take place. Nevertheless, bottled water companies are imprinted as a contribution to civil affairs resulted regarding groundwater near the companies. Therefore, a new method is required during water balance analysis in environmental effects evaluation, which should be compatible with the evaluation by hydrologic experts as well more accessible to non-experts. In this study, water level of surface water and recharge rate in subcatchment where water production wells are located were measured and monthly baseflow rates were separated from normal streams. Besides, recharge properties of groundwater and surface water in the same catchment area were estimated using analyses of oxygen and hydrogen isotopes in groundwater (production well), surface water, and rainfall.

• Journal of the Korean Society of Groundwater Environment
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• v.1 no.1
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• pp.6-9
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• 1994

Previously reported Ar/N$_2$ratios in groundwater have been measured by single ion monitoring (Barnes et al., 1975; Vogel et al., 1981; Mariotti et al., 1988). The detector geometry and flared flight tube in VG Optima isotopic ratio mass spectrometer appeared to be fortuitously aligned for the simultaneous measurement of Ar/N$_2$ratios. Method development included mechanical adjustments to optimize the mass spectrometer for Ar/N$_2$ratio measurements followed by development of a preparation system for the extraction of air-saturated water samples. Samples containing known Ar/N$_2$ratios were used to assess accuracy and precision, and to test the applicability of methods for measurements of aqueous Ar/N$_2$ratios. The results indicated that the prepared air-saturated water samples were almost identical to the predicted Ar/N$_2$ratios (p ＜0.001). Groundwater samples were collected from on-going research sites, Shelton and Grand Island, Nebraska. Samples from the Grand Island sludge injection site form a lower boundary for worldwide reported Ar/N$_2$ratios. These lower Ar/N$_2$ratios can be explained by the production of nitrogen gas from this site, where denitrification was reported previously.

• Korean Journal of Poultry Science
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• v.31 no.3
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• pp.137-143
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• 2004

The fractional synthesis rates(FSR) were measured with 2l-wk and 3l-wk-old broiler breeder pullets and hens to investigate the effect of sexual maturity on FSR. The FSR were obtained from chicken tissues and blood samples using High-Performance Liquid Chromatography/Mass Spectrometry(HPLC/MS). A L-l-13C, 15N -leucine saline solution was infused by bolus injection as a tracer into broiler breeder pullets in the experiment. A rapid HPLC/MS method was developed to measure the isotopic enrichments of leucine in plasma, tissue samples, and eggs. The enrichments of stable isotope leucine incorporated into protein and the enrichments of the stable isotope free leucine were measured in liver, breast muscle and blood samples. Two sets of experiments were conducted. In experiment one, 2l-wk-old, sexually immature broiler breeder pullets were divided into groups of three and blood samples were collected at 20 or 30 min intervals until 1.5 h from initial injection. The pullets were sacrificed in groups of three at varying time intervals for 7 h after injection. The liver, breast muscle and blood samples were removed for analysis. The FSR were estimated to be 8.7l%/day for liver, 4.06％/day for breast muscle, and 5.08％/day for blood samples in 30 minutes after injection from the enrichment ratios. In experiment two, sexually matured 3l-wk-old broiler breeder hens were assorted into groups of three and blood samples were obtained at 20 or 30 min intervals for 2 h. The FSR for blood samples were determined. The broiler breeder hens were sacrificed in groups of three at various time intervals until 7 h after injection and liver, breast muscle and blood samples were removed for analysis. The FSR were calculated to be 5.96％/day for liver. Eggs were collected from five chickens daily for 10 days after large bolus injection. The average of total enrichments of stable isotope in egg albumin was increased by 0.064% at 4 days after injection and was back to normal in 7 days.

• Journal of Ginseng Research
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• v.41 no.2
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• pp.195-200
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• 2017

Background: The natural ratios of carbon (C), nitrogen (N), and sulfur (S) stable isotopes can be varied in some specific living organisms owing to various isotopic fractionation processes in nature. Therefore, the analysis of C, N, and S stable isotope ratios in ginseng can provide a feasible method for determining ginseng authenticity depending on the cultivation land and type of fertilizer. Methods: C, N, and S stable isotope composition in 6-yr-old ginseng roots (Jagyeongjong variety) was measured by isotope ratio mass spectrometry. Results: The type of cultivation land and organic fertilizers affected the C, N, and S stable isotope ratio in ginseng (p < 0.05). The ${\delta}^{15}N_{AIR}$ and ${\delta}^{34}S_{VCDT}$ values in ginseng roots more significantly discriminated the cultivation land and type of organic fertilizers in ginseng cultivation than the ${\delta}^{13}C_{VPDB}$ value. The combination of ${\delta}^{13}C_{VPDB}$, ${\delta}^{15}N_{AIR}$, or ${\delta}^{34}S_{VCDT}$ in ginseng, except the combination ${\delta}^{13}C_{VPDB}-^{34}S_{VCDT}$, showed a better discrimination depending on soil type or fertilizer type. Conclusion: This case study provides preliminary results about the variation of C, N, and S isotope composition in ginseng according to the cultivation soil type and organic fertilizer type. Hence, our findings are potentially applicable to evaluate ginseng authenticity depending on cultivation conditions.