• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.334.2-334.2
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• 2014

본 연구에서는 a-InGaZnO (IGZO) 활성층에 대기분위기에서 열처리 온도를 각각 $150^{\circ}C$, $250^{\circ}C$, $350^{\circ}C$ 실시하여 전자구조와 광학적 특성분석 및 화학적 결합 상태의 변화를 알아보고, 이러한 물성 변화에 따른 소자의 특성을 알아 보았다. 박막 트랜지스터 소자의 전기적 특성은, IGZO 박막에 후 열처리 공정온도 후 제작한 박막 트랜지스터는 $150^{\circ}C$에서 3.1 cm2/Vs의 전계 효과 이동도와 0.38 V/decade의 문턱전압 이하 기울기를 보였으나, $350^{\circ}C$에서는 8.8 cm2/Vs의 전계 효과 이동도와 0.20 V/decade의 문턱전압 이하 기울기로 더 향상된 박막 트랜지스터의 전기적 특성 결과를 관측하였다. 전기적 소자 특성의 변화와 활성층 IGZO 박막 특성 변화와의 상관관계를 조사하기 위하여 X-ray Absorption Spectroscopy (XAS)과 Spectroscopy Ellipsometry (SE)로 측정된 흡수 스펙트럼을 통하여 3 eV 이상의 광학적 밴드 갭은 기존에 보고 되었던 a-IGZO와 유사한 특성을 보이고 있음을 확인하였고, 이러한 측정, 분석법들을 통해 후 열처리 공정 온도에 따른 밴드 갭 부근의 결함준위의 양 변화와 가전자대의 전자구조의 변화에 따라 전기적 특성이 달라짐을 확인 할 수 있었다. 또한, X-ray Photoemission Spectroscopy (XPS)를 통해 측정한 O-1s를 통해 Oxygen deficient state와 밴드 갭 부근의 결함준위와의 상관관계를 도출해낼 수 있었다. 이는 a-IGZO 활성층에 후 열처리 공정 온도 변화에 따라서 전자구조의 혼성변화와 밴드 갭 부근의 결함준위의 양의 변화, 에너지 준위의 변화 및 이와 연관된 화학적 상태 변화가 박막 트랜지스터의 특성 변화를 예상할 수 있다는 결과를 도출하였다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 somma/kms meeting
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• pp.324-324
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• 2003

• Journal of Electrochemical Science and Technology
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• 제3권4호
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• pp.178-184
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• 2012

A porous nickel (P-Ni) substrate was prepared by selective leaching of zinc from pressed pellets containing powders of Ni & Zn in 4 M NaOH solution. Anodic deposition of manganese oxide onto the porous Ni substrate ($MnO_x$/P-Ni) formed nano-flakes of manganese oxide layers as revealed in SEM studies. Pseudocapacitance of this oxide electrode was evaluated by cyclic voltammetry (CV) and chronopotentiometry (CHP) in 2 M NaOH solution. The specific capacitance of the Mn oxide electrode was as high as 1515 F $g^{-1}$, which was ten times higher than Mn oxide deposited on a flat Ni-ribbon. 80% of capacity was retained after 200 charge/discharge cycles. The system showed no loss of activity in dry form over period of days. The impedance studies indicated highly conducting $MnO_x$/P-Ni substance and the obtained specific capacitance from impedance data showed good agreement with the charge/discharge measurements.

• 대한화학회지
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• 제28권1호
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• pp.41-46
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• 1984

미량 금속원소를 농축하기 위하여 수용액중의 구리, 코발트, 니켈, 아연 및 카드뮴을 8-히드록시 퀴놀린(옥신)으로 착물을 만들고 스테아르산으로 추출하였다. 추출한 것을 녹여서 본틀에 부어 시편을 만들고 X-선 형광 분석법으로 정량하였다. 이때 침전 생성 및 추출조건, 재현성, 감도 검출한계 등에 관하여 조사하였다. 시편 제작과정의 상대 표준편차는 1.0~5.7%이고, 검출한계는 5~$50{\mu}g$/100ml이었다. 이 농축법으로 감도를 높일 수 있으며 시편 제작이 편리한 잇점이 있다.

• International Journal of Advanced Culture Technology
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• 제3권1호
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• pp.13-20
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• 2015

The self-cleaning properties of nano-zinc oxide on cotton fabrics have been investigated. The cotton fabric has been prepared by pad-dry method. The nano-zinc oxide was encapsulated in the polystyrene particle by mini-emulsion process prior used. The loading amount of zinc oxide particles into the mini-emulsion were various from 1% wt to 40%wt. The particles sizes of ZnO-encapsulated polystyrene mini-emulsion were determined using dynamic light scattering. It was showed that the particle size of the mini-emulsion was in the range of 124-205 nm. The topography and morphology of ZnO-encapsulated polystyrene which coated on cotton fabrics was observed using scanning electron microscopy. The crystal structure of ZnO-coated on cotton fabrics was explored by X-ray diffraction spectroscopy. The photocatalytic activities of zinc oxide were present through the self-cleaning properties. The presents of the zinc oxide on cotton fabrics significantly showed the improving of the self-cleaning properties under UV radiation.

• Journal of Animal Science and Technology
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• 제60권11호
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• pp.27.1-27.8
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• 2018

Background: Enteric methane ($CH_4$) accounts for about 70% of total $CH_4$ emissions from the ruminant animals. Researchers are exploring ways to mitigate enteric $CH_4$ emissions from ruminants. Recently, nano zinc oxide (nZnO) has shown potential in reducing $CH_4$ and hydrogen sulfide ($H_2S$) production from the liquid manure under anaerobic storage conditions. Four different levels of nZnO and two types of feed were mixed with rumen fluid to investigate the efficacy of nZnO in mitigating gaseous production. Methods: All experiments with four replicates were conducted in batches in 250 mL glass bottles paired with the ANKOM$^{RF}$ wireless gas production monitoring system. Gas production was monitored continuously for 72 h at a constant temperature of $39{\pm}1^{\circ}C$ in a water bath. Headspace gas samples were collected using gas-tight syringes from the Tedlar bags connected to the glass bottles and analyzed for greenhouse gases ($CH_4$ and carbon dioxide-$CO_2$) and $H_2S$ concentrations. $CH_4$ and $CO_2$ gas concentrations were analyzed using an SRI-8610 Gas Chromatograph and $H_2S$ concentrations were measured using a Jerome 631X meter. At the same time, substrate (i.e. mixed rumen fluid+ NP treatment+ feed composite) samples were collected from the glass bottles at the beginning and at the end of an experiment for bacterial counts, and volatile fatty acids (VFAs) analysis. Results: Compared to the control treatment the $H_2S$ and GHGs concentration reduction after 72 h of the tested nZnO levels varied between 4.89 to 53.65%. Additionally, 0.47 to 22.21% microbial population reduction was observed from the applied nZnO treatments. Application of nZnO at a rate of $1000{\mu}g\;g^{-1}$ have exhibited the highest amount of concentration reductions for all three gases and microbial population. Conclusion: Results suggest that both 500 and $1000{\mu}g\;g^{-1}$ nZnO application levels have the potential to reduce GHG and $H_2S$ concentrations.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.282-293
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• 2021

This paper examines gamma-ray shielding properties of SBC-Bx glass system with the chemical composition of 40SiO₂-10B₂O₃-xBaO-(45-x)CaO- yZnO- zMgO (where x = 0, 10, 20, 30, and 35 mol% and y = z = 6 mol%). Mass attenuation coefficient (µ/ρ) which is an essential parameter to study gamma-ray shielding properties was obtained in the photon energy range of 0.015-15 MeV using PHITS Monte Carlo code for the proposed glasses. The obtained results were compared with those calculated by WinXCOM program. Both the values of PHITS code and WinXCOM program were observed in very good agreement. The (µ/ρ values were then used to derive mean free path (MFP), electron density (N_eff), effective atomic number (Z_eff), and half value layer (HVL) for all the glasses involved. Additionally, G-P method was employed to estimate exposure buildup factor (EBF) for each glass in the energy range of 0.015-15 MeV up to penetration depths of 40 mfp. The results reveal that gamma-ray shielding effectiveness of the SBC-Bx glasses evolves with increasing BaO content in the glass sample. Such that SBC-B35 glass has superior shielding capacity against gamma-rays among the studied glasses. Gamma-ray shielding properties of SBC-B35 glass were compared with different conventional shielding materials, commercial glasses, and newly developed HMO glasse. Therefore, the investigated glasses have potential uses in gamma shielding applications.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.227-227
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• 2012

본 연구에서는 RF스퍼터링법에 의하여 glass substrate에 In-Zn-Sn-O (IZTO)를 Zn 성분에 변화를 주면서 $350{\AA}$ 만큼 증착시키고, 1시간 동안 $350^{\circ}C$로 열처리 하였다. In:Zn:Sn의 성분 비율은 20:48:32 (IZTO1), 13:60:27 (IZTO2)이다. 박막의 전자적, 광학적 특성은 XPS (X-ray Photoelectron Spectroscopy), REELS(Reflection Electron Energy Loss Spectroscopy), UV-Spectrometer를 이용하여 연구하였고, 박막의 전기적 특성은 van der Pauw 법을 이용하여 측정하였다. XPS측정결과, IZTO박막은 In-O, Sn-O and Zn-O의 결합을 가진다. REELS를 이용해 Ep=1,500 eV에서의 밴드갭을 얻어보면, $350^{\circ}C$로 열처리 한 박막은 열처리를 하지 않은 것에 비해 밴드갭이 IZTO1는 3.36 eV에서 3.54 eV로, IZTO2는 3.15 eV에서 3.31 eV로 증가하였다. 반면에 Zn 함량이 증가할수록 밴드갭이 감소하는 것을 확인할 수 있었다. 이 값은 UV-Spectrometer를 이용한 광학적 밴드갭과 일치하였다. 또한 van der Pauw method를 이용한 전기적 특성 분석 결과, 열처리를 하기 전에 비하여 carrier concentration이 IZTO1는 $-4.4822{\times}10^{18}cm^{-3}$에서 $-2.714{\times}10^{19}cm^{-3}$로, IZTO2는 $-3.6931{\times}10^{17}cm^{-3}$에서 $-1.7679{\times}10^{19}cm^{-3}$로 증가하였다. 반면에 Resistivity는 IZTO1의 경우 $1.7122{\times}10^{-1}{\Omega}{\cdot}cm$에서 $5.5496{\times}10^{-3}{\Omega}{\cdot}cm$로, IZTO2는 $1.3290 {\Omega}{\cdot}cm$에서 $1.3395{\times}10^{-2}{\Omega}{\cdot}cm$로 감소하였다. 그리고 UV-Spectrometer를 이용한 광학적 특성을 측정해본 결과, 가시광선영역인 380~780 nm에서의 투과율이 83%이상으로 투명전자소자로의 응용이 가능하다는 것을 보여주었다.

• 한국전기전자재료학회논문지
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• 제22권10호
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• pp.814-820
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• 2009

Antimony (Sb) doped ZnO thin films (0.1 at.%) were deposited on sapphire (0001) substrates at various temperatures (200 - 600$^{\circ}C$) by using pulsed laser deposition technique. All the thin films have been characterized by X-ray diffractometer, atomic force microscopy and spectrophotometer to investigate their structural, morphological and optical properties, respectively. Hall measurements were also carried out to identify the electrical properties of the thin films. These thin films were constituted in wurtzite structure with the preferential orientation of (002) diffraction plane and had as high as 80% optical transmission in the visible range. The bandgap energy also was determined by spectrophotometer which was around 3.28 eV. Hall measurements results revealed that the Sb dope ZnO thin film (0.1 at.%) grown at $500^{\circ}C$ exhibited p-type conduction with a carrier concentration of $8.633\times10^{16}\;cm^{-3}$, a mobility of $1.41\;cm^2/V{\cdot}s$ and a resistivity of $51.8\;\Omega{\cdot}cm$. We have successfully achieved p-type conduction in antimony doped ZnO thin films with low doping level even though the electrical properties are not favorable. This paper suggests the feasibility of p-type doping with large-size-mismatched dopant by using pulsed laser deposition.

• 조명전기설비학회논문지
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• 제14권1호
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• pp.1-6
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• 2000

Ethyl hydroxy ethyl cellulose의 고분자를 중심으로 하는 유기 결합제를 사용하고 형광체로서 ZnS:Cu와 유전체로$BaTiO_3$ 사용해 screen printing법에 의해 신광원으로서 많은 연구 개발이 집중되고 있는 유기분산형 백라이트 EL(Electroluminescent) 소자를 제조하였다. 제조된 백라이트용 유기 분산형 EL 소자의 특성은 $25[^{\circ}C]$, 100[V], 400[Hz]에서 $1.98[mA/\m^2]$의 전류밀도, O.075[W]의 power consumption, 정전용량 7.l[nF]를 나타내었다. 소자의 휘도는 50~150[V] 사이에서 $20~110[cd/\m^2]$의 밝기를 나타내였으며, 형광체의 색상변화는 ClE에 공인된 색 좌표에 의해 x=0.1711, y=0.3676의 bluish green의 색상을 나타내었다.