• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.55-56
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• 2005

The properties of phosphorus doped ZnO thin films deposited on (001) sapphire substrates by pulsed laser deposition (PLD) were investigated depending on various deposition conditions. The phosphorus (P) doped ZnO target was composed of ZnO + x wt% Al (x=1, 3, 5). The structural, electrical and optical properties of the ZnO thin films were measured by X-ray diffraction (XRD), Hall measurements and photoluminescence (PL). As the deposition temperature optimized, the electrical properties of the phosphorus doped ZnO (ZnO:P) layer showed a electron concentration of $7.76\times10^{16}/cm^3$, a mobility of 10.225 $cm^2/Vs$, a resistivity of 7.932 $\Omega$cm. It was observed the electrical property of the film was changed by dopant activation effect as target variations and deposition conditions.

• Corrosion Science and Technology
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• v.8 no.1
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• pp.40-43
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• 2009

We investigated the corrosion resistance of Zn and Cu coated steel pipes as a substitute for Cu pipe in an air-conditioner system. In addition, the galvanic corrosion tendency between two dissimilar metal parts was studied. The corrosion resistance of the Cu electroplated steel was similar to that of Cu, while the corrosion rate of the Zn electro- galvanized and the galvalume (Zn-55 % Al) coated steels was much higher and not suitable for Cu substitute in artificial sea water and acidic rain environments. Furthermore, the galvanic difference between Cu electroplated steel and Cu was so small that the Cu coated steel pipe can be used as a substitute for Cu pipe in an air-conditioner system.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.117-117
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• 1999

최근 광소자와 더불어 발전과 더불어 고효율의 새로운 광소자에 대한 수요가 증가되고 있다. ZnO는 이러한 특성을 가진 재료중에 한가지로서 최근 들어 그 가능성에 대한 연구가 활발히 이루어지고 있다. 특히 상온에서 exciton binding energy가 다른 재료보다 큰 60meV로 고효율의 blue, UV 발광이 가능한 재료로 알려져 있다. 본 연구에서도 광소자로서 ZnO를 활용하기 위해서 RF magnetron sputtering법을 이용하기 위하여 광특성의 향상에 목적을 두고 연구하였다. ZnO 박막은 RF magnetron sputtering법을 이용하여 sapphire (0001) 기판위에 성장시켰다. RF power는 60W에서 120W까지 변화시켰고 박막의 성장온도는 55$0^{\circ}C$와 $600^{\circ}C$로 변화시켰으며, 박막의 성장시간은 60분, ZnO target과 기판과의 거리는 4.5cm로 하여 성장시켰다. 성장된 ZnO 박막은 XRD $\theta$-rocking scan 측정을 통해서 박막의 C-축 배향성과 RBS channeling를 이용하여 ZnO 박막의 epitaxial 성장 정도를 측정하였다. 박막의 상온 발광 특성은 He-Cd laser를 사용한 photoluminescence spectra로 측정하였다. 또한 표면의 morphology는 atomic force microscope(AFM)를 이용하여 관찰하였으며 transmission electron microscopy(TEM)을 사용하여 ZnO박막의 단면적을 관찰함으로서 grain의 성장과 광특성 및 결정성과의 영향에 대해서 연구하였다. ZnO 박막의 성장온도 55$0^{\circ}C$에서 RF power를 60W에서 120W까지 변화시킬 경우 XRD $\theta$-rocking peak의 반치폭이 0.157$^{\circ}$에서 0.436$^{\circ}$까지 변화하였고 80W에서 최소값을 가졌으며 in-plain에 대한 XRD 측정 결과 ZnO 박막의 성장은 sapphire 기판에 대해서 30$^{\circ}$회전되어 성장된 것으로 알 수 있었으며 이는 ZnO [100]∥ Al2O3[110]의 관계를 갖는다는 것을 나타낸다. 광특성의 측정 결과인 PL peak의 반치폭은 133.67meV에서 89.5meV까지 변화함을 알 수 있었고 80W에서 최대값을 가졌으며 이는 RF power의 변화에 따른 결정성의 변화와는 반대되는 현상임을 알 수 있었다. 그러나 성장온도 $600^{\circ}C$일때에는 XRD $\theta$-rocking peak의 반치폭이 0.129$^{\circ}$로 결정성이 우수한 박막임을 확인할 수 있었고 PL peak의 반치폭 또한 Ar과 O2의 비율에 따라 76.32meV에서 98.77meV로 광특성도 우수한 것으로 나타났다. RBS channeling 결과 55$0^{\circ}C$에서는 $\chi$min값이 50~60%였으나 $600^{\circ}C$일 때에는 $\chi$min값이 4~5%로 박막이 epitaxial 성장을 하였다는 것을 알 수 있었다. 결정성과 광특성과의 연관성을 알아보기 위해 TEM을 이용한 박막의 cross section image를 관찰한 결과 광특성이 우수한 시편일수록 grain의 크기가 큰 것으로 나타났고 결정성이 우수한 시편의 경우에서는 XRD분석 결과에서처럼 C-축배향성이 우수한 것을 확인할 수 있었다. 이상의 결과로부터 RF magnetron sputtering 법으로 광특성이 우수한 양질의 ZnO박막 성장이 가능하였다는 것을 알 수 있었으며 광소자로써의 가능성을 확인 할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1782-1786
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• 2008

To investigate the characteristics of elemental components of atmospheric particles in Cheonan, atmospheric particles were sampled using a high volume air sampler equipped with a 5-stage cascade impactor during 2006. 16 elemental concentrations in fine and coarse particles were determined using ICP-AES and ICP-MS. The total mass concentrations of fine and coarse particles were 33.23 and $20.66{\mu}g/m3$, respectively, and the total elemental concentrations were 1.27, $1.71{\mu}g/m3$, occupying 3.8 and 8.3% of the total mass. Fe, Al, Ti were the most abundant elements in both fine and coarse particles, and the total Pb concentration was 84.55ng/m3, below the National standard. Enrichment factor for Sc, Cr, Cu, Zn, As, Se, Sn, Pb in fine particles were above 1,000. This indicates that the elements in fine particles are mainly from the anthropogenic sources including automobiles.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.3
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• pp.242-247
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• 1997

This study was conducted to investigate the combined effects of oyster shell, fly ash and gypsum on rice yield and quality. The four treatments of soil amelioration were oyster shell 4, fly ash 80, fly ash 56 + gypsum 24 and oyster shell 0.8 + fly ash 40 + gypsum 24 ton/ha. Rice yield were in the order of oyster shell, fly ash and control plats. The pH, EC values and OM, Ca, $SO_4$, moisture contents of the top-soil after rice harvesting in soil amelioration treatments were increased, while Mg, Na, Fe, Zn and Al were decreased than those of control. Rice quality was the best in the fly ash plat due to lower T-N and higher Mg/K ratio.

• Journal of the Korean Chemical Society
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• v.55 no.1
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• pp.19-27
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• 2011

New series of Mn(II), Ni(II), Co(II), Cu(II) and Zn(II) of the 2-(benzothiazol-2-yl)-N'-(2,5-dihydroxybenzylidene) acetohydrazide have been synthesized and characterized by elemental analysis, IR, UV-vis, $^1H$-NMR, mass and ESR spectra, magnetic susceptibility and molar conductivity measurements. The spectral data and magnetic measurements of the complexes indicate that, the geometries are either square planar or octahedral. The biological activity of the ligand and its complexes against fungi (Aspergillus nigar and Fusarium oxysporium) were investigated. The metal complexes exhibited higher activity than both the parent ligand and the corresponding metal ion.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.55-56
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• 2007

디스플레이용 전극 소재로 사용되는 투명 전도막은 높은 가시광 투과율 (89%이상)과 우수한 전기전도성(비저항 10$^{-4}{\Omega}cm$ 이하)을 동시에 가지므로 LCD, PDP, OLED 소자의 핵심소재로 인식되고 있다. 투명 전도막은 광학적 밴드갭이 3.5eV 이상인 wide-gap 반도체로서, 산화인듐($In_2O_3$)에 주석(Sn), 아연(Zn) 등을 치환고용 시킨 ITO, IZO, 산화아연(ZnO)에 Al 혹은 Ga을 치환고용 시킨 AZO, GZO 등 다양한 재료에 대한 연구가 활발하게 진행되고 있다. 본 연구에서는 플라즈마 정밀 제어 기술을 이용하여 80$^{\circ}C$이하의 저온 코팅 공정 조건에서 우수한 비저항( $2{\times}10^{-4}$ ${\Omega} cm $)을 나타낼 수 있는 TCO 코팅 공정 기술을 개발하였으며 이러한 연구결과는 차세대 디스플레이 소자로 예측되고 있는 Flexible 디스플레이 소자의 전극 재료로 활용될 수 있을 것으로 기대된다.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.889-894
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• 2001

2wt% $Al_2O_3-doped$ ZnO (AZO) thin films were deposited on sapphire (0001) single crystal substrate by parellel type rf magnetron sputtering at 55$0^{\circ}C$. The as-grown AZO thin films was polycrystalline and showed only broad deep defect-level photoluminescence (PL). In order to examine the change of PL property, AZO thin films were annealed in $N_2$ (N-AZO) and $H_2$ (H-AZO) at the temperature of $600^{\circ}C$~$1000^{\circ}C$ through rapid thermal annealing. After annealed at $800^{\circ}C$, N-AZO shows near band edge emission (NBE) with very small deep-level emission, and then N-AZO annealed at $900^{\circ}C$ shows only sharp NBE with 219 meV FWHM. In Comparison with N-AZO, H-AZO exhibits very interesting PL features. After $600^{\circ}C$ annealing, deep defect-level emission was quire quenched and NBE around 382 nm (3.2 eV) was observed, which can be explained by the $H_2$passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emission was firstly observed in AZO thin films. Moreover, peculiar PL peak around 694 nm (1.78 eV) is also firstly observed in all the H-AZO thin films and this is believed good evidence of hydrogenation of AZO. Based on defect-level scheme calculated by using the full potential linear muffin-tin orbital (FP-LMTO), the emission 3.2 eV, 3.05 eV, 3.84 eV and 1.78 eV of H-AZO are substantially deginated as exciton emission, transition from conduction band maximum to $V_{ Zn},$ from $Zn_i$, to valence band maximum $(V_{BM})$ and from $V_{o} to V_BM}$, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.3
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• pp.490-495
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• 1994

Acid phosphatase (EC3.1.3.2) from carrots was partially purified by ammonium sulfate fractionation (30%-80%), Sephacryl S-200 gel filtration, cm-Sepharose CL-6B and DEAE -Sephacel ion exchange chromatography. The optimum ph and temperature of acid phosphatase from carrots were pH 5.5 and 55$^{\circ}C$, respectively. The enzyme was most stable at ph 6.0 and relatively unstable below pH 4.0 . The activation energy of the enayme was determined to be 10.6kcal/mole. The enzyme utilized p-nitrophenyl phosphate as a substrate among tested possible substrates, whereas it hydrolyzed 5' -IMP and 5'-GMP poorly. The Michaelis -Menten constant(Km) of the enzyme with p-nitrophenyl phosphate as a substrate was identified as 0.55mM. Amongtested metal ions and inhibitors, Al+++ Zn++, Cu++ , fluoride, metavanadate and molybdate ions inhibited the enzyme activity drastically.

• Journal of the Korean Society for Heat Treatment
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• v.2 no.4
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• pp.47-55
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• 1989

The effects of thermal cycle, aging heat treatment and Boron addition on the phase transformation characteristics and mechanical properties of the shape memory alloys of Cu-Zn-Al system, which was designed to operate about $80^{\circ}C$ by this research group, were studied. From the view point of the effects of thermal cycle on the phase transformation temperature change, it was found that up to 100 cycles Ms and Af points increased by $3-7^{\circ}C$ and Mf decreased a little bit and after that all of them were remain constant, and As point was not affected. All of the phase transformation temperatures were decreased $5-7^{\circ}C$ by aging heat treatment, at $140^{\circ}C$ for 24h however the effects of thermal cycle on aged alloys were same as on unaged alloys. As the thermal cycle increased the shape memory ability decreased a little up to 20 cycles, but above that it kept almost same ability. By Boron addition, grain size was refined from $1500{\mu}m$ to about $330{\mu}m$ and the hardness, fatigue property were improved but shape memory ability was lowered.