• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.142-150
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• 2012

In this Study, Mo back electrode were deposited as the functions of various working pressure, deposition time and plasma per-treatment on sodalime glass (SLG) for application to CIGS thin film solar cell using by DC sputtering method, and were analyzed Mo change to $MoSe_2$ layer through selenization processes. And finally Mo back electrode characteristics were evaluated as application to CIGS device after Al/AZO/ZnO/CdS/CIGS/Mo/SLG fabrication. Mo films fabricated as a function of the working pressure from 1.3 to 4.9mTorr are that physical thickness changed to increase from 1.24 to 1.27 ${\mu}m$ and electrical characteristics of sheet resistance changed to increase from 0.195 to 0.242 ${\Omega}/sq$ as according to the higher working pressure. We could find out that Mo film have more dense in lower working pressure because positive Ar ions have higher energy in lower pressure when ions impact to Mo target, and have dominated (100) columnar structure without working pressure. Also Mo films fabricated as a function of the deposition time are that physical thickness changed to increase from 0.15 to 1.24 ${\mu}m$ and electrical characteristics of sheet resistance changed to decrease from 2.75 to 0.195 ${\Omega}/sq$ as according to the increasing of deposition time. This is reasonable because more thick metal film have better electrical characteristics. We investigated Mo change to $MoSe_2$ layer through selenization processes after Se/Mo/SLG fabrication as a function of the selenization time from 5 to 40 minutes. $MoSe_2$ thickness were changed to increase as according to the increasing of selenization time. We could find out that we have to control $MoSe_2$ thickness to get ohmic contact characteristics as controlling of proper selenization time. And we fabricated and evaluated CIGS thin film solar cell device as Al/AZO/ZnO/CdS/CIGS/Mo/SLG structures depend on Mo thickness 1.2 ${\mu}m$ and 0.6 ${\mu}m$. The efficiency of CIGS device with 0.6 ${\mu}m$ Mo thickness is batter as 9.46% because Na ion of SLG can move to CIGS layer more faster through thin Mo layer. The adhesion characteristics of Mo back electrode on SLG were improved better as plasma pre-treatment on SLG substrate before Mo deposition. And we could expect better efficiency of CIGS thin film solar cell as controlling of Mo thickness and $MoSe_2$ thickness depend on Na effect and selenization time.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.405-414
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• 2008

To better understand the physical processes that control the high-latitude lower thermospheric dynamics, we analyze the divergence and vorticity of the high-latitude neutral wind field in the lower thermosphere during the southern summertime for different IMF conditions. For this study the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEG CM) is used. The analysis of the large-scale vorticity and divergence provides basic understanding flow configurations to help elucidate the momentum sources that ulti-mately determine the total wind field in the lower polar thermosphere and provides insight into the relative strengths of the different sources of momentum responsible for driving winds. The mean neutral wind pattern in the high-latitude lower thermosphere is dominated by rotational flow, imparted primarily through the ion drag force, rather than by divergent flow, imparted primarily through Joule and solar heating. The difference vorticity, obtained by subtracting values with zero IMF from those with non-zero IMF, in the high-latitude lower thermosphere is much larger than the difference divergence for all IMF conditions, indicating that a larger response of the thermospheric wind system to enhancement in the momentum input generating the rotational motion with elevated IMF than the corresponding energy input generating the divergent motion. the difference vorticity in the high-latitude lower thermosphere depends on the direction of the IMF. The difference vorticity for negative and positive $B_y$ shows positive and negative, respectively, at higher magnetic latitudes than $-70^{\circ}$. For negative $B_z$, the difference vorticities have positive in the dusk sector and negative in the dawn sector. The difference vorticities for positive $B_z$ have opposite sign. Negative IMF $B_z$ has a stronger effect on the vorticity than does positive $B_z$.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.3-6
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• 2012

Purpose : Samsung medical ceter shall find a cause of the interference factor and suggest a solution for it. Materials and Methods : A sample of $^{18}F$-FDG, radioactive pharmaceuticals produced by TRACERlab MX and FASTlab synthesizer. Gel-clot method uses Positive control tube and single test tube. Kinetic chromogenic method uses ENDOSAFE-PTS produced by Charles River. Results : According to Gel clot method of Endotoxin Tests at FASTlab, both turbidity and viscosity increased at 40-fold dilution and Gel clot was detected. In case of TRACERlab MX, Gel clot was detected in most of samples but intermittently not in a few of them. When using ENDOSAFE-PTS, sample CV (Coefficient of Variation) of FASTlab is 0% at all dilution rates whereas spike CV is 0% at 1-fold dilution, 0~35% at 10-fold, 3.6~12.9% at 20-fold, 5.2~7.1% at 30-fold, 1.1~17.4% at 40-fold, spike recovery; 0% at one-fold, 25 ~ 58% at 10-fold, 50 ~ 86% at 20-fold, 70~92% at 30-fold, and 75~120% at 40-fold. Sample CV of TRACERlab MX, is 0% at all dilution rates whereas spike CV is 1.4~4.8% at one-fold dilution, 0.6~19.9% at 10-fold, spike recovery; 35~72% at one-fold dilution and 77~107% at 10-fold. Conclusion : Gel clot does not seem to occur probably to H3PO4 which engages in bonding with Mg2+ion contributing gelation inside PCT. Dilution which is identical to reducing the amount of H3PO4, could remove interfering effects accordingly. Spike recovery was obtained within 70~150% - recommended values of supplier - at 40-fold dilution even in kinetic chromogenic method.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.6
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• pp.405-415
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• 2000

To determine application rate of elemental sulfur to adjust pH of alkaline soil, buffer curve method was investigated. The elemental sulfur required to control pH 8.3 to pH 6.3 by buffer curve calculation was treated in two soils of silty loam and sandy loam, and the sulfur-mixed soils were moistened with 50% of water holding capacity during incubation of 6 weeks at $30^{\circ}C$. Soil pH was lowered with incubation and reached to target point after 4 weeks of incubation, and elemental sulfur was oxidised entirely to sulfate. This means that buffer curve has the accuracy to determine sulfur application rate in alkaline soil. However it is estimated that application rate of sulfur should be carefully determined in the field scale. Excess application of elemental sulfur resulted in extremely low soil pH and caused the hinderance of lettuce growth by nutritional imbalance and ion toxicity. To simplify the determination procedure of sulfur requirement, buffer curve method by addition of 0.1N-HCl solution as unit of mL was developed, it was compared with theroutine methods which diluted $H_2SO_4$ solution and $Ca(OH)_2$ are added as cmolc per kg soil to adjust each pH step. Buffer capacities, cmolc kg $soil^{-1}$ $pH^{-1}$, calculated from two buffer curves were not significantly different. The result indicates that buffer curve method by 0.1N-HCl can be used to adjust high pH of alkaline soil.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.7-13
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• 2015

Hydrotrope-combined copper (HCC) is a copper ($Cu^{2+}$)-based algicide, which is combined with a hydrotrope that keeps copper ion in solution to improve performance. This study assessed the growth inhibition effect of HCC against Microcystis aeruginosa which is one of the most common toxic cyanobacterium in eutrophic freshwater environment. Various HCC doses, ranging from 5.5 to $550{\mu}g/L$ as $Cu^{2+}$, were applied to either BG-11 or 1/4 diluted medium with low- or high-inoculum density of M. aeruginosa. Growth inhibition was monitored based on a decrease in chlorophyll-a content in culture medium during the incubation. Results showed that HCC significantly inhibited the growth of M. aeruginosa in a dose-dependent manner. In case of 1/4 diluted BG-11 medium, HCC dose as low as $5.5{\mu}g$ $Cu^{2+}/L$ completely inhibited the production of chlorophyll-a by M. aeruginosa. It was found that HCC did not induce any significant release of microcystin-LR from M. aeruginosa. Acute toxicity of HCC was tested using Daphnia magna, and the 24-h $EC_{50}$ value was 0.30 mg/L as $Cu^{2+}$ which was much higher than the actual inhibition dose. Ames test was performed using Salmonella enterica serovar Typhimurium TA100, and HCC showed no increase in the number of revertant colonies. The result suggested that HCC does not have any mutagenic potential in the aquatic environment. In addition, no genotoxic effect of HCC was also confirmed based on the SOS ChromoTest using Escherichia coli PQ37. Therefore, HCC could be used as a relatively safe and effective pre- and post-treatment agent to control hazardous algal blooming in aquatic environments.

• Economic and Environmental Geology
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• v.35 no.4
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• pp.325-337
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• 2002

We examined the contamination of stream water and stream sediments by heavy metal elements with respect to distance from the abandoned Backun Au-Ag-Cu mine. High contents of heavy metals (Pb, Zn, Cu, Cd, Mn, and Fe) and aluminum in the waters connected with mining and associated deposits (dumps, tailings) reduce water quality. In the mining area, Ca and SO$_4$ are predominant cation and anion. The mining water is Ca-SO$_4$ type and is enriched in heavy metals resulted from the weathering of sulfide minerals. This mine drainage water is weakly acid or neutral (pH; 6.5-7.1) because of neutralizing effect by other alkali and alkaline earth elements. The effluent from the mine adit is also weakly acid or neutral, and contains elevated concentrations of most elements due to reactions with ore and gangue minerals in the deposit. The concentration of ions in the Backun mining water is high in the mine adit drainage water and steeply decreased award to down stream. Buffering process can be reasonably considered as a partial natural control of pollution, since the ion concentration becomes lower and the pH value becomes neutralized. In order to evaluate mobility and bioavailability of metals, sequential extraction was used for stream sediments into five operationally defined groups: exchangeable, bound to carbonates, bound to FeMn oxide, bound to organic matter, and residual. The residual fraction was the most abundant pool for Cu(2l-92%), Zn(28-89%) and Pb(23-94%). Almost sediments are low concentrated with Cd(2.7-52.8 mg/kg) than any other elements. But Cd dominate with non stable fraction (68-97%). Upper stream sediments are contaminated with Pb, and down area sediments are enriched with Zn. It is indicate high mobility of Zn and Cd.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.1008-1012
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• 2008

Nanoscale zero-valent iron(nZVI) is famous for its high reactivity originated from its high surface area and it has received considerable attentions as one of the latest innovative technologies for treating contaminated groundwater. Due to its fine powdery form, nZVI has limited filed applications. The efforts to overcome this shortcoming by immobilizing nZVI on a supporting material have been made. This study investigated the differences of resin-supported nZVI's characteristics by changing the preparation methods and evaluated its reactivity. The borohydride reduction of an iron salt was proceeded in ethanol/water solvent containing a dispersant and the synthesis was conducted in the presence of ion-exchange resin. The resulting material was compared to that prepared in a conventional way of using de-ionized water by measuring the phyrical and chemical characteristics. BET surface area and Fe content of nZVI-attached resin was increased from $31.63m^2/g$ and 18.19 mg Fe/g to $38.10m^2/g$ and 22.44 mg Fe/g, respectively, by switching the solution medium from water to ethanol/water with a dispersant. The reactivity of each material was tested using nitrate solution without pH control. The pseudo first-order constant of $0.462h^{-1}$ suggested the reactivity of resin-supported nZVI prepared in ethanol/water was increased 61 % compared to that of the conventional type of supported nZVI. The specific reaction rate constant based on surface area was also increased. The results suggest that this new supported nZVI can be used successfully in on-site remediation for contaminated groundwater.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.5-13
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• 2015

A chromatographic method for the determination of imazapyr, a non-selective herbicide, in agricultural commodities was developed to use safety control of pesticide residue on crops, and was fully validated as an official method for residue analysis. Agricultural commodities, mandarin (fruit), hulled rice (cereal grains), pepper (vegetables), potato (potatoes) and soybean (beans) were extracted with methanol and partitioned with dichloromethane to remove the interference obtained from sample extracts, adjusting pH to 2.5 by 4N hydrochloric acid. Finally, they were analyzed by high performance liquid chromatography coupled to UV detector (HPLC-UVD). The developed method had the linearity in the range of test concentrations with coefficients of determination ($r^2$) more than 0.99. Recovery studies were carried out at three concentration levels (LOQ, 10LOQ, and 50LOQ) performing five replicates at each level. Recoveries were ranged between 72.1 to 108.0%, with relative standard deviations less than 10%. A consistent recovery was determined according to the CODEX guidelines (CAC/GL40, 2003). Finally, LC/MS with selected ion monitoring was also applied to confirm the suspected residues of imazapyr in agricultural samples. This developed method for determination of imazapyr residues in agricultural commodities. can be used as an official method.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.183-193
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• 2018

Currently, the Korea Atomic Energy Research Institute (KAERI) is planning to build the Ki-Jang Research Reactor (KJRR) in Ki-Jang, Busan. It is important to safely dispose of low-level radioactive waste from the operation of the reactor. The most efficient way to treat radioactive waste is cement solidification. For a radioactive waste disposal facility, cement solidification is performed based on specific waste acceptance criteria such as compressive strength, free-standing water, immersion and leaching tests. Above all, the leaching test is important to final disposal. The leakage of radioactive waste such as $^{137}Cs$ causes not only regional problems but also serious global ones. The cement solidification method is simple, and cheaper than other solidification methods, but has a lower leaching resistance. Thus, this study was focused on the development of cement solidification for an enhancement of cesium leaching resistance. We used Zeolite and Loess to improve the cesium leaching resistance of KJRR cement solidification containing simulated KJRR liquid waste. Based on an SEM-EDS spectrum analysis, we confirmed that Zeolite and Loess successfully isolated KJRR cement solidification. A leaching test was carried out according to the ANS 16.1 test method. The ANS 16.1 test is performed to analyze cesium ion concentration in leachate of KJRR cement for 90 days. Thus, a leaching test was carried out using simulated KJRR liquid waste containing $3000mg{\cdot}L^{-1}$ of cesium for 90 days. KJRR cement solidification with Zeolite and Loess led to cesium leaching resistance values that were 27.90% and 21.08% higher than the control values. In addition, in several tests such as free-standing water, compressive strength, immersion, and leaching tests, all KJRR cement solidification met the waste acceptance or satisfied the waste acceptance criteria for final disposal.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.3
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• pp.179-186
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• 2003

This pot experiment was conducted to find out the effects of boron application( $B_{0}$ ) ; control, B$_1$; 0.2, $B_2$; 2.0, $B_3$; 6.0, $B_4$; 15.0 boron me/pot) on the forage performance of pure and mixed cultures of orchardgrass and white clover. The fourth part was concerned with the changes in the contents of B, Fe, Mn, Cu, and Zn in forages. The results obtained are summarized as follows: 1. The boron(B) contents of both forages and their differences among the B treatments generally decreased according to the cutting order. The B contents of white clover were somewhat lower in the $B_{0}$ than in the $B_2$. However, the differences in the yields between $B_{0}$ and $B_2$ were relatively great. It was probably caused by the latent B-deficiency in the $B_{0}$. Compared with white clover, the B contents of orchardgrass had relatively great differences between the $B_{0}$ and B$_2$, but both yields tended to be similar. 2. The contents of Fe, Mn, Cu, and Zn in both forages were generally different according to the forage species, whether it was a pure or mixed cultures, and additional fertilization. The effects of B application on their contents were different according to the micronutrients and above factors. 3. The Fe contents of white clover were lower in the $B_{0}$ and $B_4$ than in the$ B_2$. It tended to be related to the weak growth of roots and low yields in the $B_{0}$ and $B_2$. However, there were not consistent in the changes of contents of Mn, Cu, and Zn by the rates of B application. 4. The effects of B application on the total ion concentrations of Fe, Mn, Cu, and Zn were not consistent in both forages. However, the concentrations were generally affected by the changes in the contents of Mn and Zn. The concentrations of white clover were higher in a pure than in mixed culture.