• Korean Journal of Crystallography
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• v.16 no.2
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• pp.141-148
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• 2005

It is well known that the general metals have a lot of grain boundaries. The grain boundaries play a negative role to increase the resistivity and to decrease the conductivity. The small resistivity and the large conductivity have been a goal of the material scientists, and no signal noise, perfect signal transfer, and the realization of the real sound are the dream of electronic engineers and audio manias. Generally, oxygen free copper (OFC) and Ohno continuous casting (OCC) copper cables have been used for the purpose of the precise signal transfer and low noise. However they still include a lot of grain boundaries. In our study, we have grown the single crystal by the Czochralski method and succeeded to produce single crystal wires from the crystal in the dimension of $0.5{\times}0.5{\times}2500mm$. The produced wire still possesses very good single crystal properties. We observed the structure of the wire, and measured the resistance and impedance. Glow Discharge Spectrometer (GDS) was used for analyzing the compositions of copper single crystals and commercial copper. Current-Voltage curve, resistance, total harmonic distortion and speaker frequency response were measured for comparing electrical and acoustic properties of two samples.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.76-80
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• 2003

A contractible heat pipe is designed and tested to improve cooling performance of conduction cooled superconducting magnet. When the heat pipe temperature drops below the triple point temperature, heat pipe working fluid freezes to create low pressure. From this moment the heat pipe does net work any more (OFF state) and it just works as a heat leak path when the temperature of the first stage is higher than that of the second stage. Considering small cooling capacity of the second stage around 4.2 K, the conduction loss is not negligible. Therefore, the contractible heat pipe, made of a metal bellows and copper tubes, was considered to eliminate the conduction loss. Nitrogen and argon are as working fluid of heat pipe. The copper block is cooled down with these heat pipe and the cooling performance for each heat pipe is compared. At off state, the bellows is contracted due to the low pressure of heat pipe and the evaporator section of the heat pipe is detached about 3 mm from the second stage cold head of the cryocooler. In this way, we tan eliminate the conduction loss through the heat pipe wall.

• Korean Journal of Materials Research
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• v.25 no.4
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• pp.171-176
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• 2015

We present the detection characteristics of nitrogen monoxide(NO) gas using p-type copper oxide(CuO) thin film gas sensors. The CuO thin films were fabricated on glass substrates by a sol-gel spin coating method using copper acetate hydrate and diethanolamine as precursors. Structural characterizations revealed that we prepared the pure CuO thin films having a monoclinic crystalline structure without any obvious formation of secondary phase. It was found from the NO gas sensing measurements that the p-type CuO thin film gas sensors exhibited a maximum sensitivity to NO gas in dry air at an operating temperature as low as $100^{\circ}C$. Additionally, these CuO thin film gas sensors were found to show reversible and reliable electrical response to NO gas in a range of operating temperatures from $60^{\circ}C$ to $200^{\circ}C$. It is supposed from these results that the p-type oxide semiconductor CuO thin film could have significant potential for use in future gas sensors and other oxide electronics applications using oxide p-n heterojunction structures.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.98.2-98.2
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• 2012

Thin film solar cells are growing up in the market due to their high efficiency and low cost. Especially CdTe and $CuInGaSe_2$ based solar cells are leading the other cells, but due to the limited percentage of the elements present in our earth's crust like Tellurium, Indium and Gallium, the price of the solar cells will increase rapidly. Copper Zinc Tin Sulfide (CZTS) and Copper Zinc Tin Selenide (CZTSe) semiconductor (having a kesterite crystal structure) are getting attention for its solar cell application as the absorber layer. CZTS and CZTSe have almost the same crystal structure with more environmentally friendly elements. Various authors have reported growth and characterization of CZTSe films and solar cells with efficiencies about 3.2% to 8.9%. In this study, a novel method to prepare CZTSe has been proposed based on selenization of stacked Copper Selenide ($Cu_2Se$), Tin Selenide ($SnSe_2$) and Zinc Selenide (Zinc Selenide) in six possible stacking combinations. Depositions were carried out through RF magnetron sputtering. Selenization of all the samples was performed in Close Space Sublimation (CSS) in vacuum at different temperatures for three minutes. Characterization of each sample has been performed in Field Emission SEM, XRD, Raman spectroscopy, EDS and Auger. In this study, the properties and results of $Cu_2ZnSnSe_4$ thin films grown by selenization will be presented.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.172-176
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• 2006

Fe(III)-Coated Star Fish (ICSF) was prepared by reaction of calcined Star Fish (SF) with Fe(III) solution at an elevated temperature. To investigate the stability of ICSF at acidic condition, dissolution of Fe was studied at pH 2 as a function of time. Extracted iron was negligible over the entire reaction time. This stability test suggests the applicability of ICSF in the treatment of wastewater even at low pH. Adsorption capacity of Cu(II) onto SF and ICSF was investigated in a batch and a column test. In the pH-edge adsorption, adsorption of copper onto SF and ICSF was quite similar over the entire pH range due to the presence of an important amount of Fe in SF itself. From the adsorption isotherm obtained with variation of the concentration of Cu(II), ICSF showed 1.6 times greater adsorption capacity than SF. Also, ICSF showed a greater removal capacity of Cu(II) in the column test.

• Journal of Environmental Science International
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• v.11 no.5
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• pp.411-418
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• 2002

The current study evaluated the disinfection efficiency of free chlorine and chloramine for microorganisms on various pipe materials, such as copper, galvanized steel, carbon steel, and stainless steel. In addition, the effect of internal pipe corrosion and corrosion inhibitors on the bactericidal efficiency was evaluated using a simulated loop. For disinfection with a phosphate corrosion inhibitor, chloramination was found to be more effective than chlorination due to its persistence. Free chlorine disinfection was optimized with a high phosphoric acid concentration, while chloramine disinfection was optimized with a high phosphoric acid or low polyphosphate concentration. In simulated copper and galvanized steel loop tests, chloramination with phosphoric acid was demonstrated to be more effective.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.19 no.2
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• pp.139-142
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• 2016

The coexistence of Wilson disease with Alport syndrome has not previously been reported. The diagnosis of Wilson disease and its ongoing monitoring is challenging when associated with an underlying renal disease such as Alport syndrome. Proteinuria can lead to low ceruloplasmin since it is among serum proteins inappropriately filtered by the damaged glomerulus, and can also lead to increased urinary loss of heavy metals such as zinc and copper. Elevated transaminases may be attributed to dyslipidemia or drug induced hepatotoxicity. The accurate diagnosis of Wilson disease is essential for targeted therapy and improved prognosis. We describe a patient with a diagnosis of Alport syndrome who has had chronic elevation of transaminases eventually diagnosed with Wilson disease based on liver histology and genetics.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1791-1793
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• 1998

The thin film metal electrode for PDP needs low resistivity and strong adhesion. But the sputtered copper film is weak, in the adhesion between copper and glass. In this paper, we investigated the characteristics of resistivity and adhesion about Cu thin film using Ion Beam Assisted DC Planar Magnetron Sputtering(DCPM) Device.

• Journal of Korea Foundry Society
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• v.30 no.4
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• pp.151-156
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• 2010

The high-strength low-alloy (HSLA) steels have low carbon contents (0.05~0.25% C) in order to produce adequate formability and weldability, and they have manganese contents up to 1.7%. Small quantities of silicon, chromium, nickel, copper, aluminum, molybdenum are used in various combinations. The results contained in this paper can provide the valuable information on the development of $-40^{\circ}C$ low temperature HSLA. Furthermore, the present experimental data will provide important database for casting steel materials of the offshore structure.

• Archives of Plastic Surgery
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• v.34 no.5
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• pp.543-550
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• 2007

Purpose: Diabetic foot ulcer is a representative disease of chronic would with multiple defects of wound healing factors. Many nutrition factors have been known to be essential for wound healing, but objective data are lacking. The purpose of this study is to determine those factors essential for wound healing, and to find out which of those factors are lacking in diabetic foot ulcer patients through this pilot study. Methods: We studied 100 patients who visited our clinic from March 2005 to February 2006 for treatment of diabetic foot ulcers with a duration of more than 6 weeks. We checked serum levels of protein, albumin, vitamin A, C, E, iron, magnesium, zinc, copper and hemoglobin by drawing 23cc blood after 8 hours of fasting. Protein, albumin, iron, magnesium levels were measured by colorimetry; hemoglobin levels were measured by auto analysis. Vitamin levels were measured by high performance liquid chromatography (HPLC), copper and zinc levels were measured by Inductively coupled plasma (ICP). They were compared with normal values. The patients were divided by transcutaneous oxygen pressure levels, age and sex to study the effects of these parameters. Results: 76% and 61% of patients had within-normal range serum protein and albumin levels, respectively. Among vitamins, only the level of vitamin C was low in 55% of the patients. Levels of vitamin A, E were normal or high in 93% and 100% of patients. As for trace elements, levels of iron and zinc were low in 63% and 60% of patients, but levels of magnesium and copper were usually normal or high. Levels of vitamin C, iron and zinc were lower in the low-transcutaneous oxygen pressure group. There were no definite differences according to age and sex. Conclusion: Serum levels of Hb, vitamin C, iron, zinc were low in most diabetic foot ulcer patients. The deficit was very severe in the low-transcutaneous oxygen pressure group.