• Transactions on Electrical and Electronic Materials
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• v.11 no.3
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• pp.120-125
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• 2010

For the fabrication of PMOS and integrated semiconductor devices, B, $BF_2$ and dual elements with B and $BF_2$ can be implanted in silicon. 15 keV B ions were implanted in silicon at $7^{\circ}$ wafer tilt and a dose of $3.0{\times}10^{16}\;cm^{-2}$. 67 keV $BF_2$ ions were implanted in silicon at $7^{\circ}$ wafer tilt and a dose of $3.0{\times}10^{15}\;cm^{-2}$. For dual implantations, 67 keV $BF_2$ and 15keV B were carried out with two implantations with dose of $1.5{\times}10^{15}\;cm^{-2}$ instead of $3.0{\times}10^{15}\;cm^{-2}$, respectively. For the electrical activation, the implanted samples were annealed with rapid thermal annealing at $1,050^{\circ}C$ for 30 seconds. The implanted profiles were characterized by using secondary ion mass spectrometry in order to measure profiles. The implanted and annealed results show that concentration profiles for the ${BF_2}^+$ implant are shallower than those for a single $B^+$ and dual ($B^+$ and ${BF_2}^+$) implants in silicon. This effect was caused by the presence of fluorine which traps interstitial silicon and ${BF_2}^+$ implants have lower diffusion effect than a single and dual implantation cases. For the fabricated diodes, current-voltage (I-V) and capacitance-voltage (C-V) were also measured with HP curve tracer and C-V plotter. Electrical measurements showed that the dual implant had the best result in comparison with the other two cases for the turn on voltage characteristics.

• Journal of Environmental Science International
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• v.14 no.5
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• pp.481-490
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• 2005

Surface sediments and seawater were sampled at Masan and Haengam Bays of Korea, to evaluate contamination by sewage-derived organic matter using fecal sterols, Six stream-water samples into Masan and Haengam Bays were also sampled. Total concentrations of eight sterols (coprostanol, epichloestanol, epicoprostanol, cholesterol, cholestanol, brassicasterol, stigmasterol and $\beta-sitosterol$) were in the range of $1,274\~4,768{\mu}g/g$ dry weight in suspended particulate from the stream-water, $292\~2,244{\mu}g/g$ dry weight in suspended particulate from the seawater and $4.5\~27.2{\mu}g/g$ dry weight in the sediments. Although sterol compositions in sediments, seawater and stream-water were different, cholesterol was the predominant sterol in all samples. The proportion and concentration of coprostanol, a sewage tracer, in stream-water was much higher than those in sediment and seawater. The sterol levels including coprostanol in the sediments and seawater were higher at inner basin than at the outer bay. Some molecular indices and multivariate statistical analysis were used to assess the origin of these sterols and sewage contamination in the study area. The sterol composition patterns in stream-water were mainly associated with contamination by sewage-derived organic matters and those of seawater were associated with the activities of marine-originated organisms. Sterol levels in the sediments were both from the sewage input through stream-water and the marine- originated organisms. This survey suggests that the main source/route of sewage-derived organic matters in Masan Bay is the input of stream-water into the bay.

• The Korean Journal of Nuclear Medicine
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• v.3 no.2
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• pp.1-16
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• 1969

The double tracer study on erythrokinetics was carried out experimentally with radioactive iron ($^{59}Fe$) and chromium ($^{51}Cr$) in rabbits. The 0.1% canthalidin solution and 1% pot. perchlomate solution was given subcutaneously to 20 rabbits respectively. 3 and 6 days after injection, the blood chemistry, urine examination, ferrokinetics and apparent half survival time of RBC were ($^{51}Cr\;T\frac{1}{2}$)determined. Following were the results: 1) Red blood cell hematocrit and hemoglobin values were moderately reduced and B.U.N. and serum creatinine values were slight]y inercased in the canthalidin group, while B.U.N. and serum creatinine values were within normal limits in the pot. perchlomate group. Reticulocyte values were slight]y increased in the canthalidin group, while was normal range in the pot. perchlomate group. 2) Blood chemistry finding was not significant statistically in both experimental groups, but serum iron value was moderately reduced in both group. 3) Plasma volume was unchanged in both group, but red cell volume and whole blood volume were slightly reduced in both groups. 4) Results of ferrokinetics were as follows: i) The plasma iron disappearance rate was delayed in both groups. Plasma iron turnover rate, red cell iron utilization and red cell iron turnover rate were decreased in both groups, and then red cell iron turnover rate was more decreased than plasma iron turnover rate in both groups. Circulating red cell iron was slight]y increased in canthalidin group and red cell iron concentration was within normal range in both groups. ii) P.I.T.R.-R.C.I.T. value was moderately increased in the canthalidin group and slightly increased in the pot. perchlomate group. Reticulocyte index, red cell iron turnover index, plasma iron turnover index and effective erythropoiesis index were whole]y reduced in both groups. iii) The red cell life span was slightly shortened in the canthalidin group while was within normal range in pot. perchlomate group. The pathologic finding of renal biopsy of the canthalidin group shows a selective damage in glomerulus, while shows almost normal range or slight damage in tubules. And that of the pot. perchlomate group shows a selective damage in tubules with slight damage of glomerulus.

• Korean Journal of Ecology and Environment
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• v.51 no.3
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• pp.245-252
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• 2018

Stable isotope tracers were first applied to evaluate the Microcystis cell assimilation efficiency of bivalves, since the past identification method has been limited to tracking the changes of each chl-a, clearity, and nutrient. The filter-feeders (Sinanodonta woodiana and Unio douglasiae) were assessed under the condition of cyanobacteria (Microcystis aeruginosa) blooms through an in mesocosm experiment using $^{13}C$ and $^{15}N$ dual isotope tracers. chl-a concentration in the treatment mesocosm was dramatically decreased after the beginning of the second day, ranging from 116 to $66{\mu}g\;L^{-1}$. In addition, the incorporated $^{13}C$ and $^{15}N$ atom % in the S. woodiana bivalve showed higher values than U. douglasiae bivalves. The results demonstrate that U. douglasiae has less capacity to assimilate toxic cyanobacteria derived from diet. Our results therefore also indicate that S. woodiana can eliminate the toxin more rapidly than U. douglasiae, having a larger detoxification capacity.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.5
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• pp.604-613
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• 2006

The chemical composition of $PM_{2.5}$ such as ${SO_4}^{2-},\;{NO_3}^-,\;Cl^-,\;{NH_4}^+,\;Ca^{2+},\;K^+,\;Na^+,\;Mg^{2+}$, OC, and EC and the concentrations of reactive trace gases including $O_3,\;CO,\;NOx,\;SO_2,\;and\;H_2O_2$ were measured at Gosan in Jeju Island during March $13{\sim}30$, as a part of the Atmospheric Brown Clouds-East Asian Regional Experiment 2005(ABC-EAREX2005). The average mass concentrations of $PM_{2.5}$ was 27.3 ${\mu}g/m^3$, of which OC showed the highest concentration as 4.22 ${\mu}g/m^3$ and nss ${SO_4}^{2-}$ was the second highest as 3.34 ${\mu}g/m^3$. During that period, average concentrations of CO and $O_3$ was about 300 ppbv and 56 ppbv, respectively. For the whole experiment, the correlations of CO with ${SO_4}^{2-}$ and EC were very good, which suggests that CO can be used as tracer for the formation of fine aerosols. Several pollution and dust episodes were identified by the enhancement of CO, OC, EC, nss ${SO_4}^{2-},\;or\;Ca^{2+}$ concentrations or their ratios. In conjunction with factor analysis, air trajectory analysis, and comparison with emission inventories, these results indicate the spring aerosols collected at Gosan was strongly influenced by Asian outflows.

• Journal of the Korean Chemical Society
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• v.21 no.6
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• pp.427-433
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• 1977

A neutron activation method has been developed for the simultaneous determination of chromium, iron, lanthanum, scandium and zinc in river-water samples. The sample is sealed in the silica ampoule without pretreatment and irradiated for a week at a thermal neutron flux of $1{\times}10^{13}n{\cdot}cm^{-2}{\cdot}sec^{-1}$. After cooling for about two days, the elements in the sample are sequentially extracted at different pH by 0.1M oxine-chloroform solution. The organic layers are checked by Gamma-ray spectrometry with $″3\;{\times}\;3″$ NaI (T1) detector connected to a 800-channel pulse hight analyzer. The ppb concentration of the elements in most of river-water samples could be determined by this method. The tracer study for the quantitative separation of the elements was also carried out.

• Particle and aerosol research
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• v.9 no.2
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• pp.89-102
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• 2013

24-hr $PM_{2.5}$ samples were collected from January 19 through February 27, 2009 at an urban site of Gwangju and analyzed to determine the concentrations of organic and elemental carbon(OC and EC), water-soluble OC(WSOC), eight ionic species($Na^+$, $NH^{4+}$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, $Cl^-$, ${NO_3}^-$ and ${SO_4}^{2-}$), and 22 elemental species. Haze phenomena was observed during approximately 29%(10 times) of the whole sampling period(35 days), resulting in highly elevated concentrations of $PM_{2.5}$ and its chemical components. An Asian dust event was also observed, during which $PM_{2.5}$ concentration was 64.5 ${\mu}g/m^2$. Crustal materials during Asian dust event contributed 26.6% to the $PM_{2.5}$, while lowest contribution(5.1%) was from the haze events. OC/EC and WSOC/OC ratios were found to be higher during haze days than during other sampling days, reflecting an enhanced secondary organic aerosol production under the haze conditions. For an Asian dust event, enhanced concentrations of OC and secondary inorganic components were also found, suggesting the further atmospheric processing of precursor gases during transport of air mass to the sampling site. Correlations among WSOC, EC, ${NO_3}^-$, ${SO_4}^{2-}$, and primary and secondary OC fractions, which were predicted from EC tracer method, suggests that the observed WSOC could be formed from similar formation processes as those of secondary organic aerosol, ${NO_3}^-$ and ${SO_4}^{2-}$. Results from principal component analysis indicate also that the observed WSOC was strongly associated with formation routes of the secondary organic and inorganic aerosols.

• Analytical Science and Technology
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• v.33 no.6
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• pp.245-251
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• 2020

Lead (Pb) has been shown to be a useful tracer of contamination sources and geochemical processes such as age dating and crustal evolution. These studies require a chromatographic technique for Pb separation from geological samples. This paper presents a comparison study on the effect of eluent concentration between 6M HCl and 8M HCl on the separation of Pb from Pb resin. The results showed that the separation of Pb using 6M HCl as the eluent was not effective compared to the separation using 8M HCl. To verify this method, we measured the Pb isotopic compositions of the Pb isotopic standard (NIST NBS981) and geological reference materials (BCR-2, GSP-2, and JG-1a) using a thermal ionization mass spectrometer (TIMS). The results correspond well with the reported values within the error range, implying that this method can be useful.

• Ocean and Polar Research
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• v.43 no.2
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• pp.65-72
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• 2021

In order to evaluate the dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM), as indicators of organic matter in the coastal environments, we measured the concentrations of DOC, FDOM, and chemical oxygen demand (COD) in saline groundwater (Woljeong, Pyoseon, and Hwasun beaches) and coastal seawater (Haengwon, Gwideok, Pyoseon, and Yeongnak) in Jeju, Korea. The highest concentrations of DOC and COD in groundwater were found in Woljeong and Pyoseon, and those in coastal water were observed in Haengwon and Pyoseon, indicating that the higher concentrations of DOC and COD seem to be associated with saline groundwater-driven dissolved organic matter (DOM) and/or biogeochemical processes. According to origin and optical properties of DOM using FDOM as a tracer, proportion of humic-like FDOM, more refractory DOM, was relatively greater in the groundwater than in the coastal water. With regard to this result, there was no relationship between DOC and COD in groundwater, while DOC showed a good positive correlation (r² = 0.66) with COD in coastal water. This result indicates that COD as an indicator of assessment of DOM has a limitation in which it is difficult to quantify refractory DOM. Although DOC is a potential alternative to COD in the coastal environments, particulate organic carbon cannot be negligible due to relatively higher concentration compared to the open ocean. Therefore, the use of total organic carbon (TOC) as a replacement of COD in the coastal ocean is important, and the evaluation criterion of the TOC is necessary in order to evaluate of organic matter indicator in the various coastal environments.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4236-4243
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• 2022

An industrial nuclear technique based on the use of an X-ray profiler was implemented to estimate the densities or concentrations of sediments present in an Atlantic maritime zone in the areas subjected to dredging under the governance of the Panama Canal Authority (ACP). The sediment profiles show in most areas there is a concentration of between 1.00-1.15 g/cm³ except for one area in particular, the density starts at 1.20 g/cm³ and even reaches values greater than 1.50 g/cm³; therefore, an already consolidated sediment is present, which, depending on the depth found. Values of 1.265 g/cm³, 1.297 g/cm³, 1.185 g/cm³ obtained by ACP previous studies are within the range of 1.20-1.30 g/cm³ measured with the nucleonic gauge. However, it should be noted that during the tests with the X ray profiler, sediment densities values greater than the aforementioned limit were also obtained that varying according at depths close to 12 m and 18 m with values reached up to 1.513 g/cm³ and 1.60 g/cm³, respectively. This demonstrates that sediment accumulation depends on depth. This nucleonic gauge is feasible technique for the study of the sedimentation phenomenon in channel basins and even in other projects nationwide.