• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.62-68
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• 2003

Differential pulse voltammetry (DPV) using nafion-coated glassy carbon electrodes modified with Tetren(tetraethylene pentamine)-glycerol showed sensitivity for determining lead (II) at low concentration. The Lead (II) was accumulated on the electrode surface by the formation of the complex in an open circuit, and the resulting surface was characterized by medium exchange, electrochemical reduction, and differential pulse voltammetry. Various experimental parameters, such as the composition of modifier, preconcentration time, pH of electrolyte (0.1 M acetate buffer), and parameters of differential pulse voltammetry, were optimized. The initial potential was applied for 50 s, the electrode was scanned from -0.9 to -0.3 V, and the anodic peak current was measured at -0.604 V $\pm$ 0.015 V (vs. Ag/AgCl). The calibration plot was obtained in the range 1.0$\times$10$^{-8}$ M~l.0$\times$10$^{-6}$ M with pH 4.5 buffer solution. The detection limit (3$\sigma$) it as low as 5.0$\times$ 10$^{-9}$ M. This method is applied to the determination of lead(II) in a certified reference material and the result agrees satisfactorily with the certified value.

• Corrosion Science and Technology
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• v.10 no.6
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• pp.212-217
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• 2011

In this study, corrosion characteristics of TiN and ZrN film on the abutment screw by arc-ion plating were investigated using a potentiodynamic anodic polarization test in deaerated 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The surface morphologies of the coating layers before and after corrosion test were investigated by a field-emission scanning electron microscope (FE-SEM) and a energy dispersive x-ray spectroscopy (EDS). The surfaces of the TiN and ZrN coated abutment screws showed the smooth surfaces without mechanical defects like scratches which can be formed during the manufacturing process, compared with those of the non-coated abutment screw. The corrosion and passive current densities of TiN and ZrN coated abutment screws were lower than those of the non-coated abutment screw.

• Resources Recycling
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• v.30 no.4
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• pp.54-63
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• 2021

Vanadium and tungsten can be obtained by separating/recovering the leaching solution from a spent SCR DeNO_X catalyst using the soda roasting-water leaching process. Therefore, in this study, the adsorption/desorption mechanism of vanadium and tungsten in an ion-exchange column was investigated using Lewatit MonoPlus MP 600, a strong basic anion exchange resin. The operating conditions for the separation of vanadium and tungsten in the ion-exchange column was intended to present. By conducting a continuous adsorption experiment in a pH 8.5 solution, the adsorption capacity of vanadium and tungsten was found to be 44.75 and 64.92 mg/(g of resin), respectively, which showed that the adsorption capacity of tungsten was larger than that of vanadium because of the difference in ion charge. Vanadium has a higher affinity for MP 600 than tungsten. Consequently, as the vanadium-containing solution is eluted through the ion exchange resin onto which tungsten is adsorbed, the adsorbed tungsten is exchanged with vanadium and desorbed. A continuous experiment was performed with a solution of vanadium and tungsten prepared at the same concentration as the spent SCR DeNO_X catalyst leachate. The adsorption capacity of vanadium was found to be 48.72 mg/(g of resin) and 80% of the supplied vanadium was adsorbed; in contrast, almost no tungsten was adsorbed. Therefore, vanadium and tungsten were separated effectively. The ion exchange resin was treated with 2 M HCl at 15 mL/h, and 97.7% of the vanadium(99% purity) could be desorbed. After desorption, NH₄Cl was added to precipitate ammonium polyvanadate at 90℃ and recover 93% of the vanadium.

• Journal of the Korean Society of Radiology
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• v.16 no.2
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• pp.141-150
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• 2022

The initial co-transport and counter-transport permeate transport characteristics of calcium ion at epithelial cell membrane model in parathyroid which irradiated by high energy x-ray(linac 6 MV) was investigated. The epithelial cell membrane model used in this experiment was a polysulfonated copolymerized membrane of poly(PS-DVB: polystyrene-divinylbenzene). The difference of sorbed water in membrane, fixed carrier concentration(SO₃^2-), initial pH value, OH^- concentration were occurred at difference of Ca²⁺concentration and quantity of parathyroid hormone, respectively. The initial co-transport and counter-transport permeate flux of Cl^-, OH^-, Ca²⁺ on fixed carrier concentration(SO₃^2-) and initial pH value of irradiated membrane was found to be decreased than non-irradiated membrane. The initial co-transport and counter-transport permeate flux of Ca²⁺ on fixed carrier concentration (SO₃^2-), initial pH value, OH^- concentration in irradiated membrane were found to be decreased about 2.68 ~ 6.87 times, about 1.42 ~ 1.63 times, about 2.07 ~ 1.672 times than non-irradiated membrane, respectively. As a result, the quantity of parathyroid hormone was decreased at irradiated membrane than non-irradiated membrane. The decrease of parathyroid hormone was occurred at hypoparathyroidism and osteoporosis, parathyroiditis, and so on. As the parathyroid hormone in epithelial cell membrane model were abnormal, cell damages were appeared at cell.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.117-124
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• 2003

Reinforced concrete structures under sever conditions such as marine structures, bridges and structures constructed with aggregates(dredged from sea), can be deteriorated from corrosion of the reinforcing bars. The purpose of this study is to evaluate the anti-corrosive performance of coated steel using polymer cement slurry. Polymer cement slurry with various polymer dispersions and corrosion inhibiting agent were coated to the surface of bars, and tested for accelerated corrosion tests. Tests include immersion in NaCl 10% solution, chloride ion spray, autoclave cure, autoclave cure after carbonation, penetration of NaCl 10 % solution, carbonation after penetration of NaCl 10% solution. Test results, show that the anti-corrosive performace is considerably improved by using polymer cement slurry at surface of steel. And this trend is marked by adding of corrosion inhibiting agent. This difference of the anti-corrosive properties is hardly recognized according to types of polymer dispersions. The coated steel using polymer cement slurry will be improved to a great extent compared to those of plain steel when increasing content of chloride ion in cement concrete.

• Korean Journal of Microbiology
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• v.32 no.1
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• pp.84-90
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• 1994

Kinetic parameters of various substrates and inhibitors were measured to elucidate the binding requirements of the active site of intracellular adenosine deaminase (ADA) in Aspergillus oryzae. 3'-Deoxyadenosine was the best substrate according to the value of relative kcat/$K_m$. Purine riboside was found to be the strongest inhibitor with the $K_i$ value of $3.7{\times}10^{-5}$M. Adenine acted neither as a substrate nor as an inhibitor, suggesting the presence of ribose at N-9 of adenosine was crucial to binding. ADA also catalyzed the dechlorination of 6-chloropurine riboside, generating inosine and chloride ions. Substrate specificity of 6-chloropurine riboside was 0.86% of adenosine. Purine riboside, a competitive inhibitor of ADA, inhibit the dechlorination with similar $K_i$ value, suggesting that the same binding site was involved in deamination and dechlorination. Among the sulfhydryl group reagents, mercurials, pchloromercuribenzoate (PCMB), mersalyl acid and $HgCl_2$ inactivated the enzyme. Mersalyl acid-inactivated ADA was reactivated by thiol reagents, but PCMB-inactivated enzyme was not. When ADA was treated with the mercurial reagents, the inhibition constants and inhibition patterns were determined. Each inhibition was competitive with substrate. The $K_i$ values of these mercurial reagents were lower in 10 mM phosphate buffer than in 100 mM phosphate buffer, showing phosphate dependency.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.129-135
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• 2016

This study is about ionic water generator filter Recently, a lot of people feel deep interest in health and drinking water. Evaluation of the stability of oxidation-reduced potential (ORP) using the filter of the alkaline water. This study utilizes the three filter of activated carbon, UF, carbon block in alkaline reduced water equipment. Passing the water to the filter is evaluated that the OPR values are stability in accordance with the change of the volume in the bucket. Alkaline reduced water equipment is a system that has the function of making the water reduction. This system is the values of the human body beneficial minerals and ORP are made in the functional water has a very low value than general water. Which has passed through the filter the water in the water negative ions and positive ions through the electrolytic. After electrolysis, the cathode side by water, including $Ca^+$, $K^+$, $Mg^+$, $Na^+$ water gets Alkaline Reduced Water containing the minerals beneficial to the human body. A positive electrode side is made of the organic materials that have an anion such as chlorine (Cl), phosphorus (P), sulfur(S). This experiment uses the Alkaline Reduced Water to adjust the magnitude of the voltage of the electrolysis in the Alkaline Reduced Water. That is 1st step(pH8) 2nd step (pH8.5) 3th step (pH9), 4th step (pH9.5) in the Alkaline Reduced Water and -1st step (pH6.0), -2nd step (pH5.0) used as the acidic oxidation water. When the water passes through the three filter in this system was evaluated whether the ORP values are changed and stabilized. When about 100 liters of water passing through the filter was confirmed that the ORP values are stability and evaluation.

• Journal of the Korean Vacuum Society
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• v.16 no.1
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• pp.15-22
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• 2007

We present the morphological evolution at different source powers in the ion-enhanced etching of GaAs(100) in $BCl_3-Cl_2$ plasma. With little ion bombardment at floating potential, the surface develops <110< ridges and {111} facets, as it does in purely chemical etching. The morphology develops in less than 1 minute and grows bigger over time. The etched surfaces show different morphologies at different source powers with constant pressures of gases. Lowe. source power (100 W) produces poorly developed crystallographic surfaces while higher source power (900 W) produces well developed crystallographic surfaces. This is attributed to the availability of excited reactive species(chlorine atoms) depending on source powers. With more concentration of the reactive species at higher source powers, the surface of GaAs(100) would be a surface that is expected from thermodynamics while the surface morphology would be determined by sputtering in the lack of reactive species. Statistical analysis of the surfaces, based on scaling theory, revealed two spatial exponents: one(smaller than one) is formed by atomic scale mechanisms, the other(larger than one) is formed by larger scale mechanisms which is believed to develop facets.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.3
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• pp.31-36
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• 2018

This research scrutinizes the reason of failure after pressure cooker test (PCT) for DRAM device. We use the physical inspecting tools, such as microscope, SEM and TEM, and finally find the discolor phenomenon, corrosion of Al and delamination of inter-metal dielectric (IMD) in the failed devices after PCT. Furthermore, we discover the abnormal $Al_XO_Y$ layer on Al through the careful additional measurements. To find the reason, we evaluate the effect of package ball size and pinhole in passivation layer. Unfortunately, those aren't related to the problems. We also estimate halide effect of Al. The halogens such like Cl are contained within EMC material. Those result in the slight improving of PCT characteristics but do not perfectly solve the problems. We make a hypothesis of Galvanic corrosion. We can find the residue of Ti at the edge of pad open area. We can see the improving the PCT characteristics by the time split of repair etch. The possible mechanism of the PCT failure can be deduced as such following sequence of reactions. The remained Ti reacts on the pad Al by Galvanic corrosion. The ionized Al is easily react with the $H_2O$ supplied under PCT environment, and finally transfers to the abnormal $Al_XO_Y$ layer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.5
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• pp.589-594
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• 2007

The effect of synergists having chelating ability on inhibiting browning were studied with a giucose-glutamic acid model for doenjang containing citric acid as the anti-browning agent and iron ion. The model solutions were prepared by dissolving 0.1 M glucose, 0.1 M glutamic acid, 50 mM citric acid, 0.2 mM $FeCl_2$ and synergist in 1 M phosphate buffer (pH 7.0), heating at $50^{\circ}C$ for 24 hr and storing at $30^{\circ}C\;or\;40^{\circ}C$ for four weeks. Synergists were chitosan, gallic acid, methyl benzoate, pyrophosphate and tannic acid; they were used at the following concentrations: gallic acid, pyrophosphate and tannic acid at 0.015% and 0.15%; chitosan and methyl benzoate at 0.0075% and 0.015%. Anti-browning capacities had a tendency to decrease greatly after three weeks in the case of storage at $30^{\circ}C$, whereas they decreased with storage time during storage at $40^{\circ}C$. However, anti-browning capacities of samples containing 0.015% tannic acid and 0.15% pyrophosphate were higher than that of sample without synergist by 32% after storage at $30^{\circ}C$ for four weeks. Gallic acid, tannic acid and pyrophsphate also inhibited the formation of Maillard reaction intermediates such as fluorescent compound and 3-deoxyglucosone due to the high chelating ability with iron ion after four weeks of storage at $30^{\circ}C$. The effect of these compounds on the inhibition of formation of Maillard reaction intermediates was higher at 0.15% than at 0.015%. Moreover, gallic acid increased the browning by forming colored complexes, and tannic acid generated black precipitates. Therefore, pyrophosphate of food additives was found to be the most useful synergist of citric acid, the anti-browning agent for doenjang.