• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.350-353
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• 2002

High voltage SiC Schottky barrier diodes with field plate structure have been fabricated and characterized. N-type 4H-SiC wafer with an epilayer of ∼10$\^$15/㎤ doping level was used as a starting material. Various Schottky metals such as Ni, Pt, Ta, Ti were sputtered and thermally-evaporated on the low-doped epilayer. Ohmic contact was formed at the backside of the SiC wafer by annealing at 950$^{\circ}C$ for 90 sec in argon using rapid thermal annealer. Field oxide of 550${\AA}$ in thickness was formed by a wet oxidation process at l150$^{\circ}C$ for 3h and subsequently heat-treated at l150$^{\circ}C$ for 30 min in argon for improving oxide quality. The turn-on voltages of the Ni/4H-SiC Schottky diode was 1.6V which was much higher than those of Pt(1.0V), Ta(0.7V) and Ti(0.7). The voltage drop was measured at the current density of 100A/$\textrm{cm}^2$ showing 2.1V for Ni Schottky diode, 1.45V for Pt 1.35V, for Ta, and 1.25V for Ti, respectively. The maximum reverse breakdown voltage was measured 1100V in the file plated Schottky diodes with 101an thick epilayer.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1378-1380
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• 2001

Ohmic contacts have been fabricated on p-type 4H-SiC using Pt/Ti. Low resistivitf Ohmic contacts of Pt/Ti to p-type 4H-SiC were investigated. Specific contact resistances were measured using the transmission line model method, and the physical properties of the contacts were examined using x-ray diffraction, scanning electron microscopy. Ohmic behavior with linear current-voltage characteristics was observed following anneals at $900^{\circ}C$ for 90sec at a pressure of $3.4{\times}10^{-5}$ Torr. The Pt/Si/Ti films was measured lower value of the specific contact resistance by the annealing process, and the contact resistances were improved more than one order compared to Ti contact the annealed sample. Scanning electron microscopy shows that the Pt layer effectively reduce the oxidation of Ti films. And results are obtained as $4.6{\times}10^{-4}$ ohm/$cm^2$ for a Pt/Ti metal structure after a vacuum annealing at $900^{\circ}C$ for 90sec. Titanium has a relatively high melting point, thus Ti-based metal contacts were attempted in this study.

• Carbon letters
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• v.7 no.3
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• pp.171-179
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• 2006

A carbonaceous sorbent was prepared from rice husk via sulphuric acid treatment. After preparation and washing, the wet carbon with moisture content 85% was used in its wet status in this study due to its higher reactivity towards Cr(VI) than the dry carbon. The interaction of Cr(VI) and the carbon was studied and two processes were investigated in terms of kinetics and equilibrium namely Cr(VI) removal and chromium sorption. Cr(VI) removal and chromium sorption were studied at various initial pH (1.6-7), for initial Cr(VI) concentration (100 mg/l). At equilibrium, maximum Cr(VI) removal occurred at low initial pH (1.6-2) where, Cr(III) was the only available chromium species in solution. Cr(VI) removal, at such low pH, was related to the reduction to Cr(III). Maximum chromium sorption (60.5 mg/g) occurred at initial pH 2.8 and a rise in the final pH was recorded for all initial pH studied. For the kinetic experiments, approximate equilibrium was reached in 60-100 hr. Cr(VI) removal data, at initial pH 1.6-2.4, fit well pseudo first order model but did not fit pseudo second order model. At initial pH 2.6-7, Cr(VI) removal data did not fit, anymore, pseudo first order model, but fit well pseudo second order model instead. The change in the order of Cr(VI) removal process takes place in the pH range 2.4-2.6 under the experimental conditions. Other two models were tested for the kinetics of chromium sorption with the data fitting well pseudo second order model in the whole range of pH. An increase in cation exchange capacity, sorbent acidity and base neutralization capacity was recorded for the carbon sorbent after the interaction with acidified Cr(VI) indicating the oxidation processes on the carbon surface accompanying Cr(VI) reduction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.39-43
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• 1993

Electricial characteristics of gate dielectrics prepared by reoxidation of thermal $SiO_2$ in nitrous oxide gas have been investigated. 10 and 19nm-thick oxides were reoxidized at temperatures of $900-1000^{\circ}C$ for 10-60 min in $N_2O$ ambient. As reoxidation proceeds, it is shown that nitrogen concentration at $Si/SiO_2$ interface increases gradually through the AES analysis. Nitrogen pile-up at $Si/SiO_2$ interface acts as a oxidant diffusion barrier that reduces the oxidation rate significantly. And it not only strengthen oxynitride structure at the interface but improve the gate dielectric qualities. Reliabilities of oxynitride films are conformed by the breakdown distributions and constant current stress technique. Therefore, the oxynitride films made by this process show a good promise for future ULSI applications.

• Journal of Environmental Science International
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• v.18 no.11
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• pp.1235-1245
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• 2009

The purpose of this study is to investigate electro-generation of free Cl, $ClO_2$, $H_2O_2$ and $O_3$ and degradation of Rhodamine B in solution using Ru-Sn-Sb electrode. Electrolysis was performed in one-compartment reactor using a dimensionally stable anode(DSA) of Ru-Sn-Sb/Ti as the working electrode. The effect of applied current (0.5-3 A), electrolyte type (NaCl, KCl, HCl, $Na_2SO_4$ and $H_2SO_4$) and concentration (0.5-2.5 g/L), air flow rate (0-3 L/min) and solution pH (3-11) was evaluated. Experimental results showed that concentration of 4 oxidants was increased with increase of applied current, however optimum current for RhB degradation was 2 A. The generated oxidant concentration and RhB degradation of the of Cl type-electrolyte was higher than that of the sulfate type. The oxidant concentration was increased with increase of NaCl concentration and optimum NaCl dosage for RhB degradation was 1.75 g/L. Optimum air flow rate for the oxidants generation and RhB degradation was 2 L/min. $ClO_2$ and $H_2O_2$ generation was decreased with the increase of pH, whereas free Cl and $O_3$ was not affected by pH. RhB degradation was increase with the pH decrease.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.177-184
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• 2014

In chemical vapor deposition(CVD) tungsten silicide(WSix) dual poly gate(DPG) scheme, we observed the fluorine effects on gate oxide using the electrical and physical measurements. It is found that in fluorine-rich WSix NMOS transistors, the gate thickness decreases as gate length is reduced, and it intensifies the roll-off properties of transistor. This is because the fluorine diffuses laterally from WSix to the gate sidewall oxide in addition to its vertical diffusion to the gate oxide during gate re-oxidation process. When the channel length is very small, the gate oxide thickness is further reduced due to a relative increase of the lateral diffusion than the vertical diffusion. In PMOS transistors, it is observed that boron of background dopoing in $p^+$ poly retards fluorine diffusion into the gate oxide. Thus, it is suppressed the fluorine effects on gate oxide thickness with the channel length dependency.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.6
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• pp.694-700
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• 2007

It is a gel type high functional toothpaste containing vitamin C, E, propolis extract and the rest of herb with a nanoemulsion state. Vitamin C, E is known as the material with an eminent anti-oxidation effect. Propolis is known as the material with an antimicrobial and anti-inflammatory effect. We have been succeeding in making nanoemulsion of vitamin C, E and propolis through the high pressure homogenizer using stable oil and lecithin and the gel type high functional tooth paste were made from nanoemulsion of vitamin C, E and propolis. We observed the process of wound protecting effect and cure effect for a wound of soft tissue, gingival tissue and mucous membrane showing ulcer and inflammation in oral cavity after applying a gel type high functional toothpaste to patient. As a result, the wound were healed very fast and any side effects were not shown. We confirmed that a gel type high functional toothpaste with nanoemulsion of vitamin C, E and propolis extract has good effect not only for wound healing but also for treatment of ulcer-like lesion in oral cavity. So we report our cases with review of literatures.

• Journal of the Korean Electrochemical Society
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• v.12 no.1
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• pp.54-60
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• 2009

The redox characteristics of 2-arylaldehydehydrazono-3-phenyl-5-substituted-2, 3-dihydro-1, 3, 4-thiadiazoles (1a-h) have been investigated in nonaqueous solvents such as 1, 2-dichloroethane (DCE), dichloromethane (DCM), acetonitrile (AN), Tetrahydrofuran (THF), and dimethylsulfoxide (DMSO) at platinum electrode. Through controlled potential electrolysis, the oxidation and reduction products of the investigated compounds had been separated and indentified. The redox mechanism had been suggested and proved. It had been found that all the investigated compounds were oxidized in two irreversible one-electron processes following the well-known pattern of The EC-mechanism; the first electron loss gives the corresponding cation-radical which is followed by proton removal from the ortho-position in the N-phenyl ring forming the radical. The obtained radical undergoes a second electron uptake from the nitrogen in the N = C group forming the unstable intermediate (di-radical cation) which undergoes ring closure forming the corresponding cation. The formed cation was stabilized in solution through its combination with a perchlorate anion from the medium. On the other hand, these compounds are reduced in a single two-electron process or in a successive two one-electron processes following the well known pattern of the EEC-mechanism according to the nature of the substituent; the first one gives the anion-radical followed by a second electron reduction to give the dianion which is basic enough to abstract protons from the media to saturate the (C = O) bond.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.1
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• pp.81-87
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• 2010

In this paper, we have fabricated $SiO_2$ oxidation thin films by HDP-CVD(high density plasma-chemical vapor deposition) method for passivation layer or barrier layer of OLED(organic light emitting diode). We have control and estimate the deposition rate and relative index characteristics with process parameters and get optimized conditions. They are gas flow rate($SiH_4:O_2$=30:60[sccm]), 70 [mm] distance from source to substrate and no-bias. The WVTR(water vapor transmission rate) is 2.2 [$g/m^2$_day]. Therefore fabricated thin film can not be applied as passivation layer or barrier layer of OLED.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.104-110
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• 2006

Corrosion has been around for all of recorded history. Cathodic protection is the electrical solution to the corrosion problem. Corrosion is not exactly a new topic. It has been around since the beginning of time. Corrosion is simply the loss of material resulting from current leaving a metal, following through a medium, and returning to the metal at a different point. Corrosion takes many forms and has various names, such as oxidation, rust, chemical, and bacteria action. Regardless of the agent, all corrosion is the result of electrical current flow. Various methods are used to treat corrosion or to try to prevent ti. Some of these include chemical treatment. coatings, and electrical current. Especially, proper impressed current can stop corrosive action on the protected surface. In this article, we introduce the Impressed Current Cathodic Protection (ICCP) Control and monitoring system developed by ourselves. The ICCP system is composed of a power supply, anode, reference electrode and controller. The main issue is to control the current flow on the desired value such that it is possible to force a metal to be more negative(cathodic) than the natural state. From the this process, we can achieve the cathodic protection. Of course, in the developed system, the necessary functions are possessed, such as remote control, monitoring of system fault detection etc. Some experimental results show the system performance and usefulness.