• Bulletin of the Korean Chemical Society
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• v.23 no.4
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• pp.545-549
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• 2002

A simple and rapid technique for the separation and preconcentration of lead in water and biological samples has been devised. Preconcentrationis based on the depositionof analyte onto a column packed with dithizone immobilized on sodium dodecyl sulfate coated alumina at pH $\geq$ 3. The trapped lead is eluted with 5 mL of 4 M nitric acid and determined by flame atomic absorption spectroscopy. A sample of 1 L, results in a preconcentration factor of 200 and the precision at 20${\mu}g$ $L^{-1}$ is 1.3%(n=8). The procedure is applied to tap water, well water, river water, vegetable extract and milk samples, and accuracy is assessed through recovery experiments and by independent analysis by furnace atomic absorption.

• Journal of the Korean Applied Science and Technology
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• v.25 no.1
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• pp.41-47
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• 2008

This study was conducted to made a grid alloy (Pb-Ca-Sn-Al) which has a temporary composition ratio in order to improve the efficiency of lead acid batteries. The positive activity material made a 3BS(tri-basic lead sulfate; $3PbO{\cdot}PbSO_4{\cdot}H_2O$) by a low temperature curing and it evaluates the plate efficiency through the life cycle testing. The initial current capacity of low temperature curing plate was excellent but the life cycle was not good (S1). As for the S2 plate, however, the initial current capacity and the life cycle were superior.

• Journal of the Korean Society of Radiology
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• v.7 no.6
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• pp.403-408
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• 2013

This study made a tentative estimation of the shielding rate of barium compound by thickness through monte carlo simulation to apply medical radiation shielding products that can replace existing lead. Barium sulfate($BaSO_4$) was used for the shielding material, and thickness of the shielding material specimen was simulated from 0.1 mm to 5 mm by applying $15{\times}15cm^2$ of specimen area, $4.5g/cm^3$ of density of barium sulfate, and $11.34g/cm^3$ density of lead. Entered source was simulated with 10kVp Step in consecutive X-ray energy spectrum(40 kVp ~ 120 kVp). Absorption probability in 40 kVp ~ 60 kVp showed same shielding rate with lead in 3 mm ~ 5 mm of thickness, but it was identified that under 2 mm, the shielding rate was a bit lower than the existing lead shielding material. Also, the shielding rate in 70 kVp ~ 120 kVp energy band showed similar performance as the existing lead shielding material, but it was tentatively estimated as fairly low shielding rate below 0.5 mm. This study estimated the shielding rate of barium compound as the thickness function of x-ray energy band for medical radiation through monte carlo simulation, and made comparative analysis with existing lead. Also, this study intended to verify application validity of the x-ray shielding material for medical radiation of pure barium sulfate. As a result, it was estimated that the shielding effect was 95% higher than the existing lead 1.5 mm in at least 2 mm thickness of barium compound in medical radiation energy band 70 kVp ~ 120 kVp, and this result is considered valid to be provided as a base data in weight lightening production of radiation shielding product for medical radiation.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.160-164
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• 2012

The lead-acid batteries are the most often used in human life, because of their low cost, good reversibility and high potential but they have limit cycle ability with low capacitance. The main causes of this problem are forming recrystallization of $PbSO_4$ on electrodes surface during cycles which the recrystallization of $PbSO_4$ is known as sulfation. In this study, formation process of sulfation was investigated depending on charge and discharge cycle numbers. And we decomposed sulfation to renew cycle ability of lead-acid batteries. The renewed lead-acid batteries recovered to 84% compared to first capacity after 600 cycles.

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.197-202
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• 2014

Positive plate was composed of lead hydroxide via reaction between lead oxide and $H_2O$ and lead sulfate was formed of the reaction of lead hydroxide with sulfuric acid. And its density is $3.8g/cm^3$, $4.0g/cm^3$, $4.2g/cm^3$ and $4.4g/cm^3$ by controlling volume of refined water. Curing of positive plate is done for low ($45^{\circ}C$, 40hr, over 95% of relative humidity) & high ($80^{\circ}C$, 40hr, over 95% of relative humidity) temperature, which created 3BS & 4BS active materials. Experimental result of DOD with 100% life cycle test shows that it was not related to the density of active materials but to the low & high temperature aging of active materials. The test makes us to understand that the crystallization which is made by curing of active materials is a more of a main factor than density of active materials under the deep cycle using circumstances. The active materials which were from the high temperature curing are better for deep cycle performance.

• Clinical Psychopharmacology and Neuroscience
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• v.16 no.4
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• pp.422-433
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• 2018

Objective: Neuropsychiatric manifestations like depression and cognitive dysfunction commonly occur in inflammatory bowel disease (IBD). In the context of the brain-gut axis model, colitis can lead to alteration of brain function in a bottom-up manner. Here, the changes in the response of the hypothalamic-pituitary-adrenal axis and inflammation-related markers in the brain in colitis were studied. Methods: Dextran sodium sulfate (DSS) was used to generate a mouse model of colitis. Mice were treated with DSS for 3 or 7 days and sacrificed. We analyzed the gene expression of brain-derived neurotrophic factor (BDNF), cyclooxygenase 2 (COX-2), and glial fibrillary acidic protein (GFAP), and the expression of GFAP, in the hippocampus, hypothalamus, and amygdala. Additionally, the levels of C-reactive protein (CRP) and serum cortisol/corticosterone were measured. Results: Alteration of inflammatory-related markers varied depending on the brain region and exposure time. In the hippocampus, COX-2 mRNA, GFAP mRNA, and GFAP expression were upregulated during exposure to DSS. However, in the hypothalamus, COX-2 mRNA was upregulated only 3 days after treatment. In the amygdala, BDNF and COX-2 mRNAs were downregulated. CRP and corticosterone expression increased with DSS treatment at day 7. Conclusion: IBD could lead to neuroinflammation in a bottom-up manner, and this effect varied according to brain region. Stress-related hormones and serum inflammatory markers, such as CRP, were upregulated from the third day of DSS treatment. Therefore, early and active intervention is required to prevent psychological and behavioral changes caused by IBD, and region-specific studies can help understand the precise mechanisms by which IBD affects the brain.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.87-94
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• 2021

While the shielding substances of radiation shields in medical institutions are beginning to be replaced by environmentally friendly materials, radiation protection according to the shielding properties of environmentally friendly substances is becoming an important factor rather than the existing lead shielding properties. Tungsten and barium sulfate are representative shielding materials similar to lead, and are made in sheets or fiber form with eco-friendly materials. Ytterbium is an impermeable material used as a fluorine compound in the dental radiation field. This study aims to evaluate the shielding performance in the x-ray shielding area by comparing the shielding properties of ytterbium by energy band and that of existing eco-friendly materials. When three types of shielding sheets were fabricated and tested under the same process conditions, the shielding performance of the medical radiation area was about 5 % difference from tungsten. Furthermore, shielding performance was superior to barium sulfate. In the cross-sectional structure of the shielding sheet, there was a disadvantage that the arrangement of particles was not uniform. Ytterbium oxide showed sufficient potential as a medical radiation shielding material, and it is thought that it can improve the shielding performance by controlling the particle arrangement structure and particle size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.859-862
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• 2001

This study describes a selective Ag etching solution for use with pattern on the surface of copper. This etching solution uses potassium iodide and potassium sulfate as the ligand that coordinates to the metal ions and ferricyanide as the oxidant. The etching rate was depended on the concentration of co-ligands and time. But the etching rate wasn't depended on the pH(2∼6), and oxidant(K$_3$Fe(CN)$\_$6/). Complete etching of silver can be achieved rapidly within 90sec for 4.46${\mu}$m thick metal films when aqueous solutions containing K$_3$Fe(CN)$\_$6/, K$_2$S$_2$O$\_$8/ and KI was used. This etching solution was characteristic of anisotropic etching.

• Korean Journal of Veterinary Research
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• v.25 no.2
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• pp.145-148
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• 1985

Nickel toxicity and interactions of nickel with zinc, copper, and lead were studied in glowing chicks fed supplemented diet. Feed intake and growth rate of the chick were reduced by 250mg nickel as a sulfate salt per kg of feed. The toxicity of nickel was decreased by zinc or copper supplementation, but not lead. High nickel feed increased nickel level in kidney and decreased zinc levels in tibia and plasma. However, low zinc levels in tibia and in plasma were reversed by zinc supplementation. Hemoglobin, packed cell volume, and aortic elastin content were increased in chicks fed nickel. These results suggest that nickel toxicity is induced by interference with zinc metabolism.

• Journal of the Korean Chemical Society
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• v.29 no.4
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• pp.390-396
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• 1985

The manganese was extracted from ferromanganese slag with 6N ammonium sulfate and purified with ammonium sulfide. The current efficiencies were substantially increased when small amounts of selenious acid is used as an additive. Stainless steel was used as cathodic electrode and lead (+1% Ag) as anodic electrode. The effects of several variables were investigated, and the optimum conditions were found to be; 40g/l Mn in electrolyte at pH 7.0 with 1$20g/l (NH_4)_2SO_4$, Cathode current density 60mA/cm$^2$, Current efficiency 90% and up at the temperature about $25^{\circ}C.$ The metal produced has been consistantly of high quality.