• Journal of Soil and Groundwater Environment
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• v.26 no.3
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• pp.25-36
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• 2021

This study evaluated monthly, seasonal and altitudinal changes of oxygen and hydrogen isotope compositions of wet precipitation samples (n = 238) that were collected for last four years from 7 altitudes (from 265 to 1,500 m above sea level) in the Jeju Samdasoo watershed at the southeastern part of Jeju island, in order to examine the recharge characteristics of groundwater that is pumped out for the production of the Samdasoo drinking mineral water. Precipitation samples showed a clear seasonal change of O-H isotopic composition as follow, due to the different air masses and relative humidity: 𝛿D = 7.3𝛿¹⁸O + 11.3 (R² = 0.76) in the wet season (June to September), while 𝛿D = 7.9𝛿¹⁸O + 9.5 (R² = 0.91) in the dry season (October to May). In contrast, the stable isotope compositions of groundwater were nearly constant throughout the year and did not show a distinct monthly or seasonal change, implying the well-mixing of infiltrated water during and after its recharge. An altitudinal effect of the oxygen isotope compositions of precipitation was also remarkable with the decrease of -0.19‰ (R² = 0.91) with the elevation increase by 100 m. Based on the observed altitudinal change, the minimum altitude of groundwater recharge was estimated as 1,200 m above the sea level in the Jeju Samdasoo watershed.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.2
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• pp.147-153
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• 1993

From March 1990 to August 1991, every each 5mm bulk precipitation samples were collected at one residental area in Taejon City to investigate chemical characteristics of acid rain. Major ion concentrations of rain samples $(pH, SO_4^{2-}, NO_3^-, CL^-, NH_4^+, Na^+, K^+, Ca^{2+}, Mg^{2+})$ were analysed and compared with the concentration of air pollutants (T. S. P, $SO_2, NO_x$) that were measured by Ministry of Environment. The results of statistical analysis are as followings. Rain pH was relatively high on October and January and relatively low on August, November and February. Major anion is sulfate, and it's concentration is 2.36 times higher than nitrate's, and major cations are ammonium, sodium and calcium ion. Monthly variation of sulfate and calcium concentrations are higher than the others. Ion concentration and rain pH were correlated negatively with rainfall amount. Major ions in rain samples were $SO_4^{2-}, NO_3^-, NH_4^+, Ca^{2+}$ and regression equations are proposed by multiple regression of measured data. Also, regression equation between air pollutants(T. S. P, $SO_2$) and $SO_4^{2-}, Na^+, K^+, Ca^{2+}, Mg^{2+} ions in rain samples were made. From this wer can predict rain pH.

• Bulletin of the Korean Chemical Society
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• v.18 no.11
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• pp.1172-1175
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• 1997

Calcium isotopic ratios are precisely measured by removing isobaric interferences originated from water in the plasma. Liquid Ar cryogenic trap combined with membrane desolvator could eliminate backgrounds at m/z 42 and 44. Slow drift of ICP-MS is corrected by the frequent running of the standards. It is found necessary to separate Ca from the sample matrix using Ca oxalate precipitation technique. Currently, the RSD is 0.5-1.0% for 2 minutes of measurement but is expected to be improved if the measurement time is increased. The technique was applied to 42Ca enriched baby fecal samples and successfully determined 42Ca/44Ca ratio changes.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.284.2-284.2
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• 2003

Using a column-switching technique. highly sensitive and selective semi-micro high-performance liquid chromatographic (HPLC) method has been developed for the determination of baclofen in human plasma. Following precipitation of plasma sample containing baclofen with zinc sulfate-acetonitrile, samples were directly injected on to the system. (omitted)

• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.532-541
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• 2016

The National Environmental Specimen Bank (NESB) has been collecting broad leave samples to monitor environmental pollution from five different designated sampling areas. In order to ensure the reproducibility and comparability of the results, all the procedures from selecting trees and pooling leaves to make the representative sample are defined in the standard operation procedures(the SOP). The representative samples were subjected to the chemical analyses for some heavy minerals and Polycyclic Aromatic Hydrocarbons(PAHs). The uncertainty levels involved in each step of the SOP, that is, the sampling and the chemical analysis, were derived using the Robust ANOVA, which enables the relative comparison among the different levels of pollutants concentrations with confidence. Furthermore, the effect of the varying degrees of precipitation on the pollutants concentration of the leaves was also examined. Overall, the biological difference estimated from the duplicate samples was found to exceed the variation across the site, implying even aerial deposition over site. Samples from Gwanak Mt. showed highest heavy metal concentrations than the other sites. Washing off effect of the pollutants adhering in the form of particles on the leaf surface was found to be affected by the cumulative precipitation.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.E2
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• pp.77-85
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• 2004

In order to investigate the scavenging property of airborne carbonaceous particles by precipitations, rainwater, snow sample, and total suspended particulate matter (TSP) were collected at a heavily industrialized urban site. Elemental carbon (EC) contents of both rainwater and snow water were deter-mined using elemental analysis system. EC concentrations in rain samples varied from 33.6 to 166.6 $\mu\textrm{g}$ L$^{-1}$ with an average 47.2 $\mu\textrm{g}$ L$^{-1}$ . On the other hand, those of snow samples in three times snow events were ranged from 122.4 to 293.3 $\mu\textrm{g}$ L$^{-1}$ . As might be expected, EC showed the significantly high scavenging rate at the initial rainfall. The average total carbon (TC) scavenging rate by washout mechanisms was 57.6% for five rainfall events. The scavenging rate of EC gradually increased in proportion to the increasing rainfall intensity and rainfall amount.

• Mass Spectrometry Letters
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• v.5 no.1
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• pp.30-33
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• 2014

A solid phase extraction (SPE) method was optimized for the quantitative analysis of perfluorooctanoic acid (PFOA) in serum using hydrophilic-lipophilic balance SPE and LC-MS/MS. Fetal bovine serums spiked with $^{13}C_8$-PFOA before or after SPE were used as test samples for evaluation of the SPE efficiency. Simultaneous evaluation of matrix effects and absolute SPE recovery for $^{13}C_8$-PFOA in serum using different sample pre-treatments and SPE conditions allowed optimization of SPE process efficiency with minimal matrix effect and decent SPE recovery. Introduction of protein precipitation as a sample pre-treatment procedure for serum samples before SPE generally decreased matrix effect in LC-MS/MS analysis and provided more stable recovery of PFOA.

• Journal of the Korean Chemical Society
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• v.7 no.2
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• pp.165-169
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• 1963

12 samples from an assay process chain were submitted to qualitative and quantitative neutron activation analysis for the determination of gold. Gold was detected and quantitatively determined in three samples after a chemical separation consisting of solvent extraction and precipitation steps. Recoveries ranged between 81.0 and 93.6% and results of duplicated determinations were reproducible. Quantitative data were obtained from gamma-spectrometric photopeak-area counting. Interference from fast neutron reactions was negligible.

• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.905-910
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• 1993

$\alpha$-tricalcium phosphate($\alpha$-TCP) powders were synthesized and their hydration properties were investigated in Tris. solution. Two kinds of $\alpha$-TCP powder samples were prepared; the one is reaction product of CaHPO4.2H2O and CaCO3, and another is that of hydroxyapatite(HAp) and $\beta$-Ca2P2O7. They were satisfied with Ca/P mole ratio 1.5 and were heated at 150$0^{\circ}C$ for 5 hours. In the hydration of $\alpha$-TCP samples the powder which was synthesized from HAp and $\beta$-Ca2P2O7 was hydrated faster than that from CaHPO4.2H2O and CaCO3. The hydration reaction of $\alpha$-TCP powder transformed rapidly into HAp accompanying setting and hardening. It was realized that the hydration reaction of $\alpha$-TCP was due to the solution-precipitation mechanism and the hydrates from the reaction were Ca-deficient HAp having funtional group HPO42-.

• Nuclear Engineering and Technology
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• v.10 no.1
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• pp.13-25
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• 1978

The present paper deals with the measurement of the environmental radioactivity at the Kori nuclear Power Plant site area for the Period of six years from December 1970 to December 1976. Gross alpha activity was measured in samples of airborne particulate. Gross beta measurement was performed on soil, water, airborne perticulate, pine needle, precipitation, fallout (gummed acetate paper) and various foodstuffs. Radioactivities of strontium-90 and cesium-l37 were determined by means of radiochemical analyses in samples of spinach, cabbage, barley, rice in terrestrial food, sea eel, shell fish, dulse, green laver in marine product and milk, and of fallout (cloumn), Furthermore, tritum was also analyzed in water sample of well, stream and sea by electrical enrichment.