• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2456-2458
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• 1999

The polarization mode dispersion (PMD) that restricts the transmission bandwidth was investigated in standard long single mode fiber which optimized at 1.3${\mu}m$. Although fiber has perfect circular symmetry, each optical fiber has different refractive index profiles. The investigation of PMD with random mode couplings were conducted in three kinds of fiber by the time-domain interferometric method. By using two manufacturing methods, MCVD(Modified Chemical Vapor Deposition) method and VAD(Vapor Phase Axial Deposition) method, the property of mechanical asymmetric lateral pressure, bending and twisting induced polarization mode dispersion were measured. The concatenated optical fibers were compared with other types.

• Nuclear Engineering and Technology
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• 제43권3호
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• pp.205-216
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• 2011

Recently, many research studies have investigated the enormous critical heat flux (CHF) enhancement caused by nanofluids during pool boiling and flow boiling. One of the main reasons for this enhancement is nanoparticle deposition on the heated surface. However, in real applications, nanofluids create many problems when used as working fluids because of sedimentation and aggregation. Therefore, artificial surfaces on silicon and metal have been developed to create an effect similar to that of nanoparticle deposition. These modified surfaces have proved capable of greatly increasing the CHF during pool boiling, and good results have also been observed during flow boiling. In this study, we demonstrate that the wetting ability of a surface, i.e., wettability, and the liquid spreading ability (hydrophilic surface property), are key parameters for increasing the CHF during both pool and flow boiling. We also demonstrate that when the fuel surface in nuclear power plants is modified in a similar manner, it has the same effect, producing a large CHF enhancement.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.565-566
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• 2006

In this work, We study electrical characterization of $HfO_2$/Hf/Si films grown by Atomic Layer Deposition(ALD). Through AES(Auger Electron Spectroscopy), capacitance-voltage(C-V) and current-voltage(I-V) analysis, the role of Hf layer for the better $HfO_2$/Si interface property was investigated. We found that Hf metal layer in our structure effectively suppressed the generation of interfacial $SiO_2$ layer between $HfO_2$ film and silicon substrate.

• 한국진공학회지
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• 제5권4호
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• pp.365-370
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• 1996

전기적 착색 텅스텐 산화물박막의 전자비임 증착으로 제작하였으며 제작된 막의 화학적 안정성의 기판온도 의존성을 연구하였다. 실험결과로부터, 제작된 시료의 광학적 특성과 화학적 안정성은 강하게 기판온도에 의존하였다. 기판온도 $80^{\circ}C$에서 제작된 $WO_3$막은 유기성 용액 0.6몰 $LiClO_4$속에서 착색과 탈색이 반복되어도 가장 안정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.828-830
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• 2000

Various substrates were compared for the investigation of the optical properties of ZnO thin films. ZnO thin films have been deposited on (100) p-type silicon substrates and (001) sapphire substrates by pulsed laser deposition technique using a Nd:YAG laser with the wavelength of 355 nm. Oxygen and nitrogen gases were used as ambient gases. Substrate temperatures were varied in the range of 200$^{\circ}C$ to 600$^{\circ}C$ at a fixed ambient gas pressure of 350 mTorr. ZnO films have been deposited on various substrates, such as Si and sapphire wafers. We have investigated substrate effect on the optical and structural properties of ZnO thin films using X-ray diffraction (XRD) and photoluminescence (PL).

• Carbon letters
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• 제9권1호
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• pp.17-22
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• 2008

A carbon nanotube (CNT) of diameter ~20 nm has been synthesized by spray pyrolysis of turpentine oil using Ni/Fe catalyst. Pellet of CNTs has been used as a target to produce semiconducting carbon thin film of band gap 1.4 eV. Presence of oxygen pressure in the pulse laser deposition (PLD) chamber helped to control the $sp^3/sp^2$ ratio to achieve the desired band gap. Results are discussed with the help of Raman spectra, SEM TEM micrographs and optical measurements suggest that semiconducting carbon thin film deposited by PLD technique has retained its nanotubes structure except that its diameter has increased from 20 nm to 150 nm.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.249-249
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• 2010

The effect of forming a passivation layer was investigated in superconformal Cu gap-filling of the nano-scale trench with atomic-layer deposited (ALD)-Ru glue layer. It was discovered that the nucleation and growth of Cu during metal-organic chemical vapor deposition (MOCVD) were affected by hydrogen plasma treatments. Specifically, as the plasma pretreatment time increased, Cu nucleation was suppressed proportionally. XPS and Thermal Desorption Spectroscopy indicated that hydrogen atoms passivate the Ru surface, which leads to suppression of Cu nucleation owing to prevention of adsorption of Cu precursor molecules. For gap-fill property, sub 60-nm ALD Ru trenches without the plasma pretreatment was blocked by overgrown Cu after the Cu deposition. With the plasma pretreatment, superconformal gap filling of the nano-scale trenches was achieved due to the suppression of Cu nucleation near the entrances of the trenches. Even the plasma pretreatment with bottom bias leads to the superconformal gap-filling.

• 한국표면공학회지
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• 제22권3호
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• pp.135-144
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• 1989

Aluminium Oxide was deposited with a C.V.D.-technique on various substrates. The effects of various treating condition such as temperature, time, heat resistance and composition of substrates were investigated in order to understand the relationship of structure, property and process. Grain size depends upon the activity of adsorption siite and coarsened with increasing temperature and time. Deposition rate decreases in order of electrolytic iron, carbon steel STS430 and STS304, since the active site for adsorption of reactant was more decreased for Cr and Ni than Fe. Oxidation resistance of alumina coated specimens improved markedely and that of stainless steel was prominent.

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.58-63
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• 2019

Lithium-ion batteries used for IT, automobiles, and industrial energy-storage devices have battery management systems (BMS) to protect the battery from abnormal voltage, current, and temperature environments, as well as safety devices like, current interruption device (CID), fuse, and vent to obtain positive temperature coefficient (PTC). Nonetheless, there are harmful to human health and property and damage the brand image of the manufacturer because of smoke, fire, and explosion of lithium battery packs. In this paper, we propose a systematic protection algorithm combining battery temperature, over-current, and interconnection between protection elements to prevent copper deposition, internal short circuit, and separator shrinkage due to frequent and instantaneous over-current discharges. The parameters of the proposed algorithm are suggested to utilize the experimental data in consideration of battery pack operating conditions and malicious conditions.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.251-251
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• 2016

For several decades, industrial processes consume a huge amount of raw water for various objects that consequently results in the generation of large amounts of wastewater. Wastewaters are consisting of complex mixture of different inorganic and organic compounds and some of them can be toxic, hazardous and hard to degrade. These effluents are mainly treated by conventional technologies such are aerobic and anaerobic treatment and chemical coagulation. But, these processes are not suitable for eliminating all hazardous chemical compounds form wastewater and generate a large amount of toxic sludge. Therefore, other processes have been studied and applied together with these techniques to enhance purification results. These include photocatalysis, absorption, advanced oxidation processes, and ozonation, but also have their own drawbacks. In recent years, electrochemical techniques have received attention as wastewater treatment process that could be show higher purification results. Among them, boron doped diamond (BDD) attract attention as electrochemical electrode due to good chemical and electrochemical stability, long lifetime and wide potential window that necessary properties for anode electrode. So, there are many researches about high quality BDD on Nb, Ta, W and Si substrates, but, their application in effluents treatment is not suitable due to high cost of metal and low conductivity of Si. To solve these problems, Ti has been candidate as substrate in consideration of cost and property. But there are adhesion issues that must be overcome to apply Ti as BDD substrate. Al, Cu, Ti and Nb thin films were deposited on Ti substrate to improve adhesion between substrate and BDD thin film. In this paper, BDD films were deposited by hot filament chemical vapor deposition (HF-CVD) method. Prior to deposition, cleaning processes were conducted in acetone, ethanol, and isopropyl alcohol (IPA) using sonification machine for 7 min, respectively. And metal layer with the thickness of 200 nm were deposited by DC magnetron sputtering (DCMS). To analyze microstructure X-ray diffraction (XRD, Bruker gads) and field emission scanning electron microscopy (FE-SEM, Hitachi) were used. It is confirmed that metal layer was effective to adhesion property and improved electrode property. Electrochemical measurements were carried out in a three electrode electrochemical cell containing a 0.5 % H2SO4 in deionized water. As a result, it is confirmed that metal inter layer heavily effect on BDD property by improving adhesion property due to suppressing formation of titanium carbide.