• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.38-39
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• 2003

전기적 저항이 낮은 투명 박막 물질은 현재 flat panel display, electroluminescent device, thin film transistor, solar cell 등 여러 분야에서 연구되고 있다. 그 중에서도 특히 ZnO：Ga는 현재 많이 쓰이는 ITO보다 화학적, 열적으로 안정한 상태를 보이는 투명 전도 산화막 물질로써 본 연구에서는 분광타원법을 이용하여 ZnO：Ga의 광학적 특성을 분석하였다. 본 연구를 위한 시료는 온도에 따른 ZnO：Ga／Sapphire 박막, $O_2$의 압력에 따른 ZnO：Ga／Sapphire 박막, Ga의 doping 농도에 따른 ZnO：Ga／Sapphire 박막으로 제작하였으며, 위상변조형 분광타원계(spectroscopic Phase Modulated Ellipsometer, Jobin-Yvon, UVISEL)를 사용하여 측정대역을 0.74 ~ 4.5 eV, 입사각을 70$^{\circ}$로 하여 측정하였다. (중략)

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.5
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• pp.481-488
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• 2013

Nitric oxide ($NO_x$) formation characteristics in non-premixed diffusion flames of methane fuels have been investigated experimentally and numerically by adding 10% ammonia to the fuel stream, according to the variation of the oxygen ratio in the oxidizer with oxygen/carbon dioxide and oxygen/nitrogen mixtures. In an experiment of coflow jet flames, in the case of an oxidizer with oxygen/carbon dioxide, the $NO_x$ emission increased slightly as the oxygen ratio increased. On the other hand, in case of an oxygen/nitrogen oxidizer, the $NO_x$ emission was the maximum at an oxygen ratio of 0.7, and it exhibited non-monotonic behavior according to the oxygen ratio. Consequently, the $NO_x$ emission in the condition of oxyfuel combustion was overestimated as compared to that in the condition of conventional air combustion. To elucidate the characteristics of $NO_x$ formation for various oxidizer compositions, 1D and 2D numerical simulations have been conducted by adopting one kinetic mechanism. The result of 2D simulation for an oxidizer with oxygen/nitrogen well predicted the trend of experimentally measured $NO_x$ emissions.

• Korean Journal of Materials Research
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• v.2 no.1
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• pp.35-42
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• 1992

Thermal behavior of residue and damaged layer formed by reactive ion etching (RIE) in $CHF_3/C_2F_6$ were investigated using X-ray photoelectron spectroscopy(XPS) and secondary ion mass spec-trometry(SIMS) techniques. Decomposition of polymer residue film begins at $200^{\circ}C$ and above $400^{\circ}C$ carbon compound as graphite mainly forms by in-situ resistive heating. It reveals that thermal decomposition of residue can be completed by rapid thermal anneal treatment above $800^{\circ}C$ under nitrogen atmosphere and out-diffusion of carbon and fluorine of damaged layer is observed.

• Polymer(Korea)
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• v.34 no.2
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• pp.108-115
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• 2010

The effects of acid-treated MWCNT and coupling agent on properties of MWCNT/SBR are investigated in this work. The MWCNTs oxidized using sulfuric and nitric acids were analyzed by the Raman scattering and Fourier transformed infrared spectroscopy(FT-IR). The FT-IR results indicate the presence of -COOH groups in the treated samples, and Raman spectroscopy of the acidtreated MWCNTs further corroborates the formation of surface defect due to the introduction of carboxyl groups. And the nanocomposites reinforced with MWCNTs were characterized extensively using the scanning electron microscopy(SEM), electrical conductivity, thermal conductivity, and tensile properties measurements. The results showed that nanocomposites onto acid-treated MWCNTs enhanced mechanical properties compared to those containing MWCNTs without acid treatment. These findings confirmed the improved interfacial interactions between MWCNTs and SBR arising from the coupling agents. But the electrical and thermal conductivity of nanocomposites decreased due to the chopping and formation of surface defects of MWCNTs.

• Journal of the Korean Magnetics Society
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• v.12 no.2
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• pp.64-67
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• 2002

IrMn pinned spin valve (SV) films with stacks of Ta/NiFe/IrMn/CoFe/Cu/CoFe/NiFe/Ta were prepared by dc sputtering onto thermally oxidized Si (111) substrates at room temperature under a magnetic field of about 100 Oe. The annealing cycle number and temperature dependence of exchange coupling field (H$_{ex}$), magnetoresistance (MR) ratio, and coercivity (H$_{c}$) were investigated. By optimizing the process of deposition and post thermal annealing condition, we obtained the IrMn based SV films with MR ratio of 3.6%, H$_{ex}$ of 1180 Oe for the pinned layer. The H$_{ex}$ is stabilized after the second annealing cycle and it is thought that this SV reveals high thermal stability. The H$_{ex}$ maintained its strength of 600 Oe in operation up to 24$0^{\circ}C$ and decreased monotonically to zero at 27$0^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.165-165
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• 2010

GaInZnO는 투명 비정질 산화물 반도체로서 태양전지, 평판 액정 디스플레이, 잡음방지 코팅, 터치 디스플레이 패널, 히터, 광학 코팅 등 여러 응용에 쓰인다. 이 논문에서는 투명전자소자로 관심을 모으고 있는 GaInZnO의 전자적 그리고 전기적 특성을 측정하였다. GaInZnO 박막은 $SiO_2$ (100)/Si 기판위에 RF 마그네트론 스퍼터링 증착법으로 $Ga_2O_3:In_2O_3:ZnO$의 조성이 2:2:1로 된 타겟을 가지고 박막을 성장시켰다. 성장한 후에 RTP를 이용하여 30분간 열처리 하였다. GaInZnO의 전자적 특성을 나타내는 띠틈 및 실리콘 기판과의 원자가 띠 오프셋 값을 측정하였으며, 이 값들을 통해 GaInZnO박막과 실리콘 기판과의 띠 정렬도 수행하였다. 띠틈은 반사 전자 에너지 손실 분광법(REELS)을 이용하여 측정하였고, 원자가 띠 오프셋은 광전자 분광법(XPS)을 이용하여 측정하였다. 열처리 온도가 $400^{\circ}C$까지는 띠틈의 변화 및 XPS 결합에너지의 변화가 없는 것으로 보아 열적안정성이 우수함을 알 수 있다. 반면 $450^{\circ}C$에서의 띠틈이 감소하는 것으로 보아 $450^{\circ}C$에서는 열적안정성이 깨지는 것을 알 수 있다. GaInZnO 박막을 채널 층으로 하고 전극은 알루미늄(Al)으로 된 TFT를 제작하여 전기적 특성을 조사하였다. TFT 특성 결과 이동도가 약, subthreshold swing(S.S)이 약 1.5 V/decade, 점멸비가 약 $10^7$으로 측정되었다. 유리 위에 증착시킨 GaInZnO 박막의 투과율을 측정해본 결과 모든 시료가 가시광선 영역에서 80%이상의 투과율을 갖는 것으로 보아 투명전극소자로 응용이 가능하다는 것을 알 수 있었다.

• Polymer(Korea)
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• v.38 no.2
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• pp.232-239
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• 2014

Poly(lactic acid)(PLA) nanocomposites containing various nanofillers were synthesized using the solution intercalation method. Organically modified bentonite clay (NSE), octadecylamine-graphene oxide (ODA-GO), and an NSE/ODA-GO complex were utilized as nanofillers in the fabrication of PLA hybrid films. PLA hybrid films with varying nanofiller contents in the range of 0-10 wt% were examined and compared in terms of their thermomechanical properties, morphologies, and oxygen permeabilities. Transmission electron microscopy (TEM) confirmed that most of the NSE and ODA-GO nanofillers were dispersed homogeneously throughout the PLA matrix on the nanoscale, although some agglomerate NSE/ODA-GO complex particles were also formed. Among the three nanofillers for PLA hybrid films, the NSE/ODA-GO complex showed the best improvement in film thermal stability. In contrast, NSE and ODA-GO exhibited the best improvement in tensile mechanical properties and oxygen barrier properties of the PLA hybrid films, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.302-302
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• 2012

최근 비 휘발성 메모리 시장의 확대와 수요가 많아지면서, 비휘발성 메모리 소자의 제작에 대한 연구가 활발히 진행되고 있다. 특히, 실리사이드 나노입자를 적용한 소자는 현 실리콘 기반의 반도체 공정의 적용이 용이하다. 따라서 본 연구에서는 실리사이드 계열의 화합물 중에서 일함수가 4.63 eV인 Vanadium silicide (V3Si) 나노입자 메모리소자를 제작하여 전기적 특성과 열 안정성에 대하여 알아보았다. p-Si기판에 약 6nm 두께의 SiO2 터널층을 건식 산화 방법으로 성장시킨 후 V3Si 나노입자를 제작하기 위해서 V3Si 금속박막을 스퍼터링 방법으로 4 nm~6 nm의 두께로 터널 절연막 위에 증착시켰다. 그리고 컨트롤 절연막으로 SiO2를 초고진공 스퍼터를 이용하여 50 nm 증착하였고, 급속 열처리 방법으로 질소 분위기에서 $800^{\circ}C$의 5초 동안 열처리하여 V3Si 나노 입자를 형성하였다. 마지막으로 200 nm두께의 Al을 증착하고, 리소그래피 공정을 통하여 채널 길이와 너비가 각각 $2{\mu}m$, $5{\mu}m$, $10{\mu}m$를 가지는 트랜지스터를 제작하였다. 제작된 시편의 V3Si 나노입자의 크기와 균일성은 투과 전자 현미경으로 확인하였고, 후 열처리 공정 이후 V3Si의 존재여부의 확인을 위해서 X-ray 광전자 분광법의 표면분석기술을 이용하여 확인하였다. 소자의 전기적인 측정은 Agilent E4980A LCR meter, 1-MHz HP4280A와 HP 8166A pulse generator, HP4156A precision semiconductor parameter analyzer을 이용하여 측정온도를 $125^{\circ}C$까지 변화시키면서 전기적인 특성을 확인하였다. 본 연구에서는 온도에 선형적 의존성을 가지는 전하누설 모델인 T-model 을 이용하여 나노입자 비휘발성 메모리소자의 전하누설 근원을 확인한 후, 메모리 소자의 동작 특성과의 물리적인 연관성을 논의하였다. 이를 바탕으로 나노입자 비휘발성 메모리소자의 열적안정성을 확보하고 소자 특성향상을 위한 최적화 구조를 제안하고자 한다.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.167-172
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• 2012

A new type of thermoplastic elastomer (TPE) based on EPDM ionomer as an elastomer and polyamide-6 as a reinforcing crystalline polymer was prepared and the thermal properties of TPEs were investigated. Especially effects of neutralization of maleated EPDM (MA-EPDM) to prepare EPDM ionomer with zinc oxide and the content of polyamide-6 on the thermal properties of the blends were investigated. Both the neutralization and blending were carried out employing a twin screw extruder. It was found that the neutralization of MA-EPDM results in the increase of cooling crystallization temperatures. Polyamide-6 plays the role of reinforcing filler in the blends due to the high crystallinity. Fine dispesion of polyamide-6 in the blends was confirmed and attributed to the imide formation between the maleic anhydride of MA-EPDM and amine group of polyamide-6. TPEs based on EPDM ionomer/Polyamide-6 blends showed balanced mechanical properties with improvement in heat resistance.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.82-87
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• 2011

Heat transfer oils are used in applications such as heating systems of chemical plant, refinery heat exchange systems, gas plant process, injection molding systems, and pulp and paper processing. These oils are extremely stable and resistance to thermal and oxidative degradation. In the event of a spill or accidental release of heat transfer oils, it can be ignite easily when there is an ignition source. This paper discusses the flammability and thermal stabilities of new and used oils. The flammability of the oils are assessed by measuring changes in flash point and auto ignition temperature. The thermal stability of oils are evaluated by the thermal screening unit ($TS^u$) and the differential scanning calorimeter (DSC). From the experimental results, it is suggested to give fire hazard characteristics to safe precautions for the proper use and treatment of heat transfer oils.