• Journal of Electrochemical Science and Technology
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• v.8 no.4
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• pp.274-281
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• 2017

This paper describes the simple fabrication of an electrode modified with electrochemically reduced graphene oxide (ERGO) for the simultaneous electrocatalytic detection of dopamine (DA), ascorbic acid (AA), and uric acid (UA). ERGO was formed on a glassy carbon (GC) electrode by the reduction of graphene oxide (GO) using linear sweep voltammetry. The ERGO/GC electrode was formed by subjecting a GO solution ($1mg\;mL^{-1}$ in 0.25 M NaCl) to a linear scan from 0 V to -1.4 V at a scan rate of $20mVs^{-1}$. The ERGO/GC electrode was characterized by Raman spectroscopy, Fourier transform infrared spectroscopy, contact angle measurements, electrochemical impedance spectroscopy, and cyclic voltammetry. The electrochemical performance of the ERGO/GC electrode with respect to the detection of DA, AA, and UA in 0.1 M PBS (pH 7.4) was investigated by differential pulse voltammetry (DPV) and amperometry. The ERGO/GC electrode exhibited three well-separated voltammetric peaks and increased oxidation currents during the DPV measurements, thus allowing for the simultaneous and individual detection of DA, AA, and UA. The detection limits for DA, AA, and UA were found to be 0.46, 77, and $0.31{\mu}M$ respectively, using the amperometric i-t curve technique, with the S/N ratio being 3.

• Analytical Science and Technology
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• v.10 no.3
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• pp.216-224
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• 1997

In the study of cyclic voltammogram of rubeanic acid, rubeanic acid has two reduction peaks; first peak is similar with that of $S^{2-}$ and thiourea, which is conceded to by HgS, second peak is very weak and unidentified. The study also describes the differential pulse cathodic stripping voltammetric method for the determination of rubeanic acid. The followings were optimal conditions of rubeanic acid for the study : 0.05M borate buffer solution(pH 10.0) ; an accumulation potential of -0.30V(vs. Ag/AgCl); accumulation time of 120sec. : scan rate of 10mV/sec. The detection limit of trace analysis shows $2.7{\times}10^{-8}M$ of rubeanic and at optimal conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.5
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• pp.750-756
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• 1994

The effect of onion juice on ethanol -induced lipid peroxidation were studied were studied in rats. The contents of thiobarbituric acid (TBA) -reactants increased significantly in liver thanol(4ml/kg/day) administered -rats. The activities of serum alanine aminotransferase and alkaline phosphatase increased by ethanol administration compared with control group, but alterations of antioxidant enzymes activities in liver of ethanol administered rats were not significant vs control group. The glutathione contents in liver decreased by ethanol , whereas the glutathione level increased in ethanol and onion juice group compared with ethanol group. The contents of hepatic TBA-reactants and serum aminotrasnferase activity in ethanol group were reduced by onion juice administration. In these results, increased hepatic TBA-reactants of liver in ethanol group might be due to decreased glutathione contents in liver. Reduced glutathione (GSH) plays an important roles in the liver in several detoxification and the reduction of lipid peroxides. So the protective effects of onion juice on ethanol-induced increment of TBA-reactants may be due to the increament of lgutathions content. The glutathione depletion by ethanol was an important factor of ethanol-induced cell damage, and the prevention of onion juice to the glutathione depletion reduced by ethanol may be an important factor on the protection from ethanol-induced lipid perpxidation in rats.

• Carbon letters
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• v.26
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• pp.88-94
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• 2018

This manuscript explains the effective determination of urea by redox cyclic voltammetric analysis, for which a modified polypyrrole-graphene oxide (PPY-GO, GO 20% w/w of PPY) nanocomposite electrode was developed. Cyclic voltammetry measurements revealed an effective electron transfer in 0.1 M KOH electrolytic solution in the potential window range of 0 to 0.6 V. This PPY-GO modified electrode exhibited a moderate electrocatalytic effect towards urea oxidation, thereby allowing its determination in an electrolytic solution. The linear dependence of the current vs. urea concentration was reached using square-wave voltammetry in the concentration range of urea between 0.5 to $3.0{\mu}M$ with a relatively low limit of detection of $0.27{\mu}M$. The scanning electron microscopy was used to characterize the morphologies and properties of the nanocomposite layer, along with Fourier transform infrared spectroscopy. The results indicated that the nanocomposite film modified electrode exhibited a synergistic effect, including high conductivity, a fast electron-transfer rate, and an inherent catalytic ability.

• Journal of Chest Surgery
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• v.27 no.11
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• pp.942-947
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• 1994

Post-thoracotomy pain is so severe that lead to postoperative pulmonary complications due to the patient`s inability to cough, deep breathing and chest wall motion. Many authors have been trying to reduce the post-thoracotomy pain, but there is no method of complete satisfaction. In 1990, we reported the result that the cryoanalgesia reduce the immediate postoperative pain significantly. We try to compare the effect of cyroanalgesia with the effect of Bupivacain intercostal nerve block for the post-thoracotomy pain control. Ninety patients, who undergoing thoracotomy in Korea University Medical Center Guro Hospital between the January 1993 and September 1993, were evaluated. The patients were divided into three groups : Group A, control, the patients without pain control procedure [N=30], Group B, the patients with Bupivacain intercostal nerve block [N=30], Group C, the patients with cryoanalgesia [N=30]. Postoperative analgesic effects were evaluated by the scoring system which made arbiturary by author. The results were that the Bupivacain intercostal nerve block markedly reduced the immediate postoperative pain compare with two other groups, the cryoanalgesia reduced the immediate postoperative pain significantly compare with control group, the pain reduction effect of the two groups- cryoanalgesia and Bupivacain intercostal nerve block- were not different at postoperative seventh day, probably due to the action time of Bupivacain and the result that there were no significant complications of the procedures.

• Journal of Environmental Health Sciences
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• v.37 no.6
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• pp.467-473
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• 2011

Objectives: Wastewater treatment plants typically produce a large volume of waste sludge. In this study, the conditioning and dewatering properties of a digested and thickened sludge from an industrial wastewater treatment plant were investigated in order to improve the dewaterbility of the sludge. Methods: Jar-tests and Buchner funnel tests were carried out to assess the conditioning and dewatering properties of a waste sludge. TTF (Time to Filter Test) and SRF (Specific Resistance to Filtration) were adopted as the indices of sludge dewaterbility. Results: The valuation indices influencing the dewaterbility of the waste sludge, including TTF, SRF, water contents, VS/TS ratio and turbidity, were measured. The TTF and SRF of the digested and thickened sludge were decreased to 40 sec, $3.43{\times}10^{12}$ m/kg, and 39 sec, $1.09{\times}10^{12}$ m/kg, respectively. Conclusions: The conditioner composed of natural inorganic materials turned out to be effective in the reduction of sludge water contents.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.20-23
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• 2001

Hypereutectic Al-25Si alloy, which is expected to be applied to the cylinder-liner-part of the engine-block of an automobile due to its excellent wear resistance, low density and low thermal expansion coefficient, has been fabricated through a spray forming process. The obtained microstructure of the hypereutectic Al-25Si alloy appeared to consist of Al matrix and equiaxed Si particles of average diameter of 5-7 mm. To characterize the deformation behavior of this alloy, a series of load relaxation and compression tests have been conducted at temperatures ranging from RT to $500^{\circ}C$. The strain rate sensitivity parameter (m) of this alloy has been found to be very low (0.1) below $400^{\circ}C$ and reached maximum value of about 0.2 at $500^{\circ}C$. During the deformation above $300^{\circ}C$ in compression, strain softening has been observed. The diagram of extrusion pressure vs. ram-speed has been constructed. The extrusion has been successfully conducted at the temperatures of $300^{\circ}C$ and above with the ratio of area reduction of 28 and 40 in this study.

• Progress in Superconductivity
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• v.12 no.2
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• pp.99-103
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• 2011

We performed angle resolved photoelectron spectroscopy (ARPES) studies on Ru doped $BaFe_2As_2$ with various Ru contents. Ru, which is doped into a parent compound $BaFe_2As_2$ and substitute Fe, does not donate or accept electrons. However, it induces superconductivity. From ARPES data along the high symmetry cuts and Fermi surface maps, we investigate the electron correlation and carrier density at the Fermi level. We observe that the Fermi velocity increases with Ru doping, suggesting reduction in electron correlation. In addition, we address issues on local vs. itinerant pictures for the magnetism in $BaFe_2As_2$.

• Journal of Chest Surgery
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• v.45 no.6
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• pp.390-395
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• 2012

Background: Conventional open repair is a suboptimal therapy for blunt traumatic aortic injury (BTAI) due to the high postoperative mortality and morbidity rates. Recent advances in the thoracic endovascular repair technique may improve outcomes so that it becomes an attractive therapeutic option. Materials and Methods: From August 2003 to March 2012, 21 patients (mean age, 45.81 years) with BTAI were admitted to our institution. Of these, 18 cases (open repair in 11 patients and endovascular repair in 7 patients) were retrospectively reviewed and the early perioperative results of the two groups were compared. Results: Although not statistically significant, there was a trend toward the reduction of mortality in the endovascular repair group (18.2% vs. 0%). There were no cases of paraplegia or endoleak. Statistically significant reductions in heparin dosage, blood loss, and transfusion amounts during the operations and in procedure duration were observed. Conclusion: Compared with open repair, endovascular repair can be performed with favorable mortality and morbidity rates. However, relatively younger patients who have acute aortic arch angulation and a small aortic diameter may be a therapeutic challenge. Improvements in graft design, delivery sheaths, and graft durability are the cornerstone of successful endovascular repair.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3261-3266
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• 2014

A pellet of polycrystalline $CuGaO_2$ with a delafossite structure was prepared from $Ga_2O_3$ and CuO by high-temperature solid-state synthesis. The $CuGaO_2$ pellet was a p-type semiconductor for which the electrical conductivity, carrier density, carrier mobility and Seebeck coefficient were $5.34{\times}10^{-2}{\Omega}^{-1}cm^{-1}$, $3.5{\times}10^{20}cm^{-3}$, $9.5{\times}10^{-4}cm^2V^{-1}s^{-1}$ at room temperature, and $+360{\mu}V/K$, respectively. It also exhibited two optical transitions at about 2.7 and 3.6 eV. The photoelectrochemical properties of the $CuGaO_2$ pellet electrode were investigated in aqueous electrolyte solutions. The flat-band potential of this electrode, determined using a Mott-Schottky plot, was +0.18 V vs SCE at pH 4.8 and followed the Nernst equation with respect to pH. Under UV light illumination, a cathodic photocurrent developed, and molecular hydrogen simultaneously evolved on the surface of the electrode due to the direct reduction of water without deposition of any metal catalyst.