• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1596-1601
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• 2007

Aluminum doped zinc oxide (AZO) thin films were deposited on coming glass substrates using an Nd:YAG pulsed laser deposition technology. The AZO thin films were deposited with various growth conditions such as the substrate temperature and oxygen partial pressure. In this work, we used various measurement technologies in order to investigate the electrical, structural, and optical properties of the AZO thin films. Among the AZO thin films, the one prepared at the substrate temperature of $300^{\circ}C$ and oxygen partial pressure of 5 mTorr showed the best properties of an electrical resistivity of $4.63{\times}10^{-4}{\Omega}{\cdot}cm$, a carrier concentration of $9.25{\times}10^{20}cm^{-3}$, and a carrier mobility of $31.33cm^2/V{\cdot}s$. All the AZO thin films showed an high average optical transmittance over 90 % in visible region.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.315-322
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• 2002

A thin film oxide semiconductor micro gas sensor array which shows only 60㎽ of power consumption at an operating temperature of 30$0^{\circ}C$ has been fabricated using microfabrication and rnicrornachining techniques. Excellent thermal insulation of the membrane is achieved by the use of a double la! or structure of 0.1${\mu}{\textrm}{m}$ thick Si$_3$N$_4$ and 1${\mu}{\textrm}{m}$ thick phosphosilicate glass(PSG) prepared by low pressure chemical vapor deposition(LPCVD) and atmospheric－pressure chemical-vapor deposition(APCVD), respectively. The sensor way consists of such thin film oxide semiconductor sensing materials as 1wt.％ Pd-doped SnO$_2$, 6wt.% AI$_2$O$_3$-doped ZnO, WO$_3$ and ZnO. The thin film oxide semiconductor micro gas sensor array exhibited resistance changes usable for subsequent data processing upon exposure to various gases and the sensitivity strongly depended on the sensing layer materials. Heater Part of the sensor structure has been modified in order to improve the process yield of the sensor, and as a result of modified heater structure improved process yield has been achieved.

• Korean Journal of Materials Research
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• v.7 no.7
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• pp.564-570
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• 1997

용융산화에 의한 AI$_{2}$O$_{3}$복합재료의 형성에 미치는 합금원소의 영향을 연구하였다. AI-Mg-3Si 합금이 가장 우수한 산화거동을 보였다. 우수한 3원계로 선정된 AI-1Mg-3Si합금에 제 4원소 Sn, Cu, Ni, Zn을 양을 달리하여 각각 첨가하여 산화거동을 살펴보았다. 1273K, 1373K, 1473K, 에서 20시간 각각 산화실험을 한 결과, 1473K에서는 모든 합금계가 우수했으나 1373K, 1273K에서는 산화가 거의 일어나지 않았다.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.192-195
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• 2005

The silicon thin film solar cells were fabricated by 13.56 MHz PECVD (Plasma-Enhanced Chemical-Vapor Deposition) and 60 MHz VHF PECVD (Very High-Frequency Plasma-Enhanced Chemical-Vapor Deposition). We focus on textured ZnO:Al films prepared by RF sputtering and post deposition wet chemical etching and studied the surface morphology and optical properties. These films were optimized the light scattering properties of the textured ZnO:Al after wet chemical etching. Finally, the textured ZnO:Al films were successfully applied as substrates for silicon thin films solar cells. The efficiency of tandem solar cells with $0.25 cm^2$ area was $11.8\%$ under $100mW/cm^2$ light intensity. The electrical properties of tandem solar cells were measured with solar simulator (AM 1.5, $100 mW/cm^2)$ and spectral response measurements.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.2-2
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• 1999

금속재료의 표면 특성을 높이기 위해서 여러 표면처리 방법들이 사용되어져 오고 있다. 그 중 용사법에 의한 코팅방법이 최근의 현저한 기술적인 진보와 새로운 용사재료의 개발 등에 의해 여러 분야에 널리 응흉되고 있다. 일반적으로 이 용사법에 의한 코팅층은 다리, 선박 등의 대형 구조물에 대한 내식성 향상뿐만 아니라 자동차 및 항공기 부품, 핵 반응기 등의 코팅부에 널리 이용되고 였다. 특히 해수분위기에서 주로 사용되는 설비의 내식성을 향상시킬 목적으로 사용되 는 알루마늄 및 아연 합금의 용사 코팅층은 대부분의 경우 건조한 분위기보다는 수분이 많은 수용액 환경 하에서 사용되므로, 사용 환경 중에서 용사피막의 내식성을 조사하는 연구가 요구되고 있다. 사용되는 환경하에서의 침지시험에 의한 방법도 중요하지만, 가속화된 전기화학측정에 의한 방법 또한 이용된다. 열용사법에 의한 코팅층의 전기화학적 특성을 알아보기 위해서 3.5 % NaCI 수용액 내에서 AI 5 5083 모재와 Al-2%Zn 합금의 용사 코팅층 각각에 대한, 그리고 AI 5083 모재 위 AI-2%Zn 용사층이 코팅된 경우에 대한 분극거동과 침지시간에 따른 부식전위 및 분극저항성의 특성변화, 표면의 임피던스특성 변화 등을 측정하였다. 이 결과 모재에 대한 코팅층의 희생양극성올 판단할 수 있고, 모재/코팅 사스템의 분극거동은 혼성전위이론(mixed-potential theory)에 의해 결정되었다. 용사 코팅층이 박리되어 모재가 일부 드러난 경우를 모사한 시험편올 제작하고, 시험편 표면의 각 위치에 따라 부식전위 분포를 측정하였다. 그리고 측정 데이터를 기초로 표면의 상태변화를 모사하여 용사코팅에 의한 표면에서의 방식전위분포를 시율레이션하였다. 이와 같은 표면에서의 방식전위분포 해석을 통하여, 코팅층의 희생양극성에 의한 모재의 방식범위를 판단할 수 있다.의 비저 항을 갖는 철 박막에서도 99.9% 순도의 철을 타켓으로 하여 증착된 막은 일반 저탄소 강을 타켓으로 하여 증착된 막보다 훨씬 낮은 부식속도를 보였다.TEX>$He/O_2/Ar/N_2$의 gas를 사용 한 atmospheric pressure plasma cleaning 과 $Ar/O_2$의 gas를 사용한 ICP cleaning에서 이 차전자방출계수(SEEC)가 약 1.5~2.5배 증가된 것을 알 수 있었다. 저지능 등을 평가하여 각 실험결과를 비교분석하여 보았다. 수록 민감하여 304 의 IGSCC 와 매우 유사한 거동을 보인다. 본 강연에서는 304 와 600 의 고온 물에서 일어나는 IGSCC 민감도에 미치는 환경, 예민화처리, 합금원소의 영향을 고찰하고 이에 대한 최근의 연구 동향과 방식 방법을 다룬다.다.의 목적과 지식)보다 미학적 경험에 주는 영향이 큰 것으로 나타났으며, 모든 사람들에게 비슷한 미학적 경험을 발생시키는 것 이 밝혀졌다. 다시 말하면 모든 사람들은 그들의 문화적인 국적과 사회적 인 직업의 차이, 목적의 차이, 또한 환경의 의미의 차이에 상관없이 아름다 운 경관(High-beauty landscape)을 주거지나 나들이 장소로서 선호했으며, 아름답다고 평가했다. 반면에, 사람들이 갖고 있는 문화의 차이, 직업의 차 이, 목적의 차이, 그리고 환경의 의미의 차이에 따라 경관의 미학적 평가가 달라진 것으로 나타났다.corner$적 의도에 의한 경관구성의 일면을 확인할수 있지만 엄밀히 생각하여 보면 이러한 예의 경우도 최락의 총체적인 외형은 마찬가지로 $\ulcorner$순응$\lrcorner$의 범위를 벗어나지 않는다. 그렇기 때문에도 $\ulcorner$순응$\lrcorne

• Journal of Energy Engineering
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• v.13 no.1
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• pp.75-81
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• 2004

ZZFCa sorbents for hot gas desulfurization in IGCC were prepared by adding calcium oxide to ZZF sorbent in order to improve its attrition resistance in this study. ASTM attrition test for the sorbent was performed at several different weight percentages of CaO to investigate the attrition characteristics of ZBFCa sorbents as a function of CaO content. Attrition index of ZZF without CaO was 28.3% and its collected attrition index was 10.8％. ZZFCa-3 containing 3 wt% CaO showed the lowest attrition index (AI=17.3％, CAI=8.8％) in the test. From the results of SEM morphologies and particle size distribution measurements, ZZFCa-3 maintained a fine shape and a desirable average particle size even after attrition test. In the experiments of sulfidation/regeneration for ZZFCa-3 sorbent concentration of hydrogen sulfide in coal gas was lowered from 10000 ppm to below 1 ppm. Sulfur removing capacity was about 28.8 g S/100 g sorbent. Neither formation of CaSO$_4$ was observed in XRD measurement nor SO$_2$ slippage was observed during sulfidation process.

• Journal of Energy Engineering
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• v.12 no.4
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• pp.302-308
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• 2003

The peformence tests of zinc-based desulfurization sorbents using the yellow earth as support for the hot gas clean up were carried out. The zinc-based sorbent with 25 wt％ yellow earth was prepared, and their properties such as the reaction rate, the sulfur capacity and the attrition resistance, were investigated. The reactivity tests for hot gas desulfurization was performed at middle temperatures (sulfidation/regeneration：480$^{\circ}C$/580$^{\circ}C$). During multi-cyclic desulfurization, the deactivation of zinc-based sorbent was decreased by the addition of yellow earth, and their efficiency was enhanced. The ZnO/yellow earth sorbent had high reactivity, good regenerability, long-term durability (about 19 gS/100 g sorbent for 10-cycles) and high attrition resistance (AI=19.1％). It was concluded that the peroperties of zinc-based sorbent were improved by metal oxides (Fe$_2$O$_3$, Na$_2$O, MnO$_2$, etc) in the yellow earth. From these results, it was confirmed that the desulfurization properties of zinc-based sorbents at middle temperatures could be improved by the yellow earth using as support.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.196-200
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• 2005

In this work, we investigated simple Aㅣ/TCO/a-Si:H(n)/c-Si(p)/Al hetero-junction solar cells prepared by low temperature processes, unlike conventional thermal diffused c-Si solar cells. a-Si:H/c-Si hetero-junction solar cells are processed by low temperature deposition of n-type hydrogenated amorphous silicon (a-Si:H) films by plasma-enhanced chemical vapor deposition on textured and flat p-type silicon substrate. A detailed investigation was carried out to acquire optimization and compatibility of amorphous layer, TCO (ZnO:Al) layer depositions by changing the plasma process parameters. As front TCO and back contact, ZnO:Al and AI were deposited by rf magnetron sputtering and e-beam evaporation, respectively. The photovoltaic conversion efficiency under AMI.5 and the quantum efficiency on $1cm^2$ sample have been reported. An efficiency of $12.5\%$ is achieved on hetero-structure solar cells based on p-type crystalline silicon.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.691-698
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• 2010

In this study Al-doped ZnO (AZO) thin films have been fabricated on Eagle 2000 glass substrates at various substrate temperature ($100{\sim}500^{\circ}C$) and working pressure (10 ~ 40 mTorr) by RF magnetron sputtering in order to investigate the structural, electrical, and optical properties of the AZO thin films. The obtained films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The AZO thin films, which were deposited at $T=300^{\circ}C$ for 10 mTorr, shows the highest (002) orientation, and the full width at half maximum (FWHM) of the (002) diffraction peak is $0.42^{\circ}$. The lowest resistivity ($2.64{\times}10^{-3}\;{\Omega}cm$) with the highest cartier concentration ($5.29{\times}10^{20}\;cm^{-3}$) and a Hall mobility of ($6.23\;cm^2/Vs$) are obtained in the AZO thin films deposited at $T=300^{\circ}C$ for 10 mTorr. The optical transmittance in the visible region is approximately 80%, regardless of process conditions. The optical band-gap depends on the Al doping level as the substrate temperature increases and the working pressure decrease. The optical band-gap widening is proportional to cartier concentration due to the Burstein-Moss effect.

• Economic and Environmental Geology
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• v.31 no.5
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• pp.399-413
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• 1998

Daegang granite is located around the Namwon-gun, Cheolabuk-do, and is an elongate stock $(80 km^{2})$ in the NNE-SSW direction. Daegang granite has the very same mineralogical and geochemical characteristics as those of the typical A-type granites; (1) it is a one feldspar hypersolvus granite, and is classified as an alkali feldspar granite in the lUGS scheme, (2) has small amounts of Fe-rich biotite (annite) and alkali amphibole (ribeckite) that are late in the crystallization sequence of the granitic magma, (3) always contains opaque oxides, fluorite and zircon, (4) shows high and quite homogeneous $SiO_2$, content (mostly 72~77 wt.%) and $(Na_{2}O+K_{2}O)/Al_{2}O_{3}$ ratio (0.90~0.98), (5) contains high Ga, lOOOO*Ga/Ai, $K_{2}O+Na_{2}O$, $(K_{2}O+Na_{2}O)/CaO$, $K_{2}O/MgO$, FeO/MgO, agpaitic index, Zr, Nb, Ce, Y, Zn value or ratio that resemble to those of the Australian A-type granites (Whalen et al., 1987), and (6) has enriched LREE and HREE that show flat variation pattern with slightly depleted in HREE and profound Eu anomalies (Eu/Eu*=0.04~0.l4). In the tectonic discrimination diagrams of Pearce et al. (1984) and Eby (1992), Daegang granite is classified as a within plate granite and $A_{2}-type$.