• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.37-37
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• 2010

2008년 동아시아 대륙에서 발생기원이 다른 황사와 인위적 오염입자의 광역적 이동 사례를 NOAA위성 RGB 합성영상과 지상 TSP, PM10, PM2.5 질량농도 관측으로 구별하였다. 또한 Terra/Aqua 위성MODIS (MODerate Imaging Spectroradiometer) 센서의AOD (Aerosol Optical Depth)와 FW (Fine aerosol Weighting)를 통해 동아시아 지역에서 발생기원이 다른 대기 에어로졸의 분포와 입자 크기 특성을 분석하였다. 중국 북부와 몽골, 그리고 중국 황토고원에서 모래폭풍이 발생하여 광역적으로 이동하여 청원에 먼지입자(황사)로 영향을 주는 6 사례를 분석했다. 질량농도 TSP중 PM10 은 70%, PM2.5 는 16% 로 조대입자 (> $2.5{\mu}m$)의 비율이 큰 것은 사막과 반사막의 자연적 발생원에서 생성되었기 때문이다. 그러나, 모래 폭풍이 이동 과정에서 중국 동부의 산업 지역을 거쳐 유입 되는 사례에서는 TSP 중 PM2.5 가 23% 까지 증가하기도 했다. 중국 동부로부터 황해를 거쳐 한반도로 유입하고 있는 다른5사례는 TSP 중 PM10, PM2.5가 각각 82%, 65% 로 PM2.5 의 비율이 높았는데 인위적 오염입자의 영향 때문이다. 동아시아 지역에서 인위적 오염입자의 광역적 이동 사례에 대한 평균 AOD는 $0.42{\pm}0.17$로 황사에 의한 AOD ($0.36{\pm}0.13$)와 비교하여 대기 에어로졸에 대한 비율이 높게 나타났다. 특히, 중국 동부에서 황해, 한반도, 동해에 이르는 광역적 지역에 높은 AOD값이 분포했다. 인위적 오염입자의 사례는 FW가 평균 $0.63{\pm}0.16$로 모래폭풍의 이동 사례의 $0.52{\pm}0.13$ 보다 높은 값을 보이고 있어, 대기 에어로졸에 대한 인위적 미세 오염입자의 기여가 크게 나타나고 있었다.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.123-128
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• 2017

Nanostructured materials have received attention due to their unique electronic, optical, optoelectrical, and magnetic properties as a results of their large surface-to-volume ratio and quantum confinement effects. Thermal chemical vapor deposition process has attracted much attention due to the synthesis capability of various structured nanomaterials during the growth of nanostructures. In this study, silicon oxide nanowires were grown on Si\$SiO_2$(300 nm)\Pt(5~40 nm) substrates by two-zone thermal chemical vapor deposition with the source material $TiO_2$ powder via vapor-liquid-solid process. The morphology and crystallographic properties of the grown silicon oxide nanowires were characterized by field-emission scanning electron microscope and transmission electron microscope. As results of analysis, the morphology, diameter and length, of the grown silicon oxide nanowires are depend on the thickness of the catalyst films. The grown silicon oxide nanowires exhibit amorphous phase.

• Elastomers and Composites
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• v.45 no.3
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• pp.206-211
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• 2010

Zinc oxide(ZnO) nanoparticles were synthesized by reacting an aqueous-alcoholic zinc nitrate solution to sodium hydroxide under ultrasonic irradiation at room temperature. The fullerene($C_{60}$) and ZnO nanoparticles were heated individually in an electric furnace for two hours at $700^{\circ}C$. The morphology and optical properties of the $C_{60}$ and ZnO nanoparticles were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and ultraviolet/visible (UV-vis) spectroscopy. The photocatalytic activity of the heated and unheated the $C_{60}$ and ZnO nanoparticles for the decomposition of methylene blue(MB), methyl orange(MO) and rhodamine B(RhB) was examined using UV-vis spectroscopy.

• Korean Journal of Crystallography
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• v.1 no.2
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• pp.66-75
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• 1990

The Pd-Te system has been investigated by differential thermal analysis, X-ray diffration, electron probe microanalysis and reflected light microscopy. New phase relations in 0-50at% Te portion of the binary system are proposed. Eight binary phases exist in the system:Pd17Te4, Pd20Te7.PdsTe3, P477e3, P497e4, P637e2, PeTe and PaTe2. Of these, P677e3 is a newly reported phase. P4177e4 is cubic, space group Fd3c, with a=12.678(5)A. The X-ray powder data of PdsTe3, indexed on an orthorhombic cell, give a= 12.843(3), b=15.126(3), c: 11.304(2)A and those of PdTTe.1, indexed on a monoclinic cell, give a=7.444(1), b= 13.918(2) , c=8.873(2)A. p =92.46(2). Some physical and optical properties of synthetic phases in the system are also reported.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.6
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• pp.392-397
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• 2018

In this paper, the ZnS nanoparticles were synthesized according to the process conditions of hydrothermal synthesis. When the molar ratio of Zn to S was 1:1.2, it was confirmed that it had a cubic single phase and a high crystal phase. After the molar ratio is fixed, hydrothermal synthesis was conducted at $180^{\circ}C$ for 24, 36, 72 and 96 h in order to confirm the structural change with the change of hydrothermal synthesis times. As the hydrothermal synthesis times increased, the particle size increased. The hydrothermal synthesized particle size for 72 h was considered to be suitable for sintering. The ZnS ceramic had a density of 99.7% and an excellent transmittance of ~70% in the long-wavelength region.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1993-1998
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• 2011

Semiconductor industry needs to have fine patterns in order to fabricate the high density integrated circuit. For nano-scale patterns, hard-mask is used to multi-layer structure which is formed by CVD (chemical vaporized deposition) process. In this work, we prepared single-layer hard-mask by using organic-inorganic hybrid polymer for spin-on process. The inorganic part of hard-mask was much easier etching than photo resist layer. Beside, the organic part of hard-mask was much harder etching than substrate layer. We characterized the optical and morphological properties to the hard mask films using organic-inorganic hybrid polymer, and then etch rate of photo resist layer and hard-mask film were compared. The hybrid polymer prepared from organic and inorganic materials was found to be useful hard-mask film to form the nano-patterns.

• Resources Recycling
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• v.7 no.3
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• pp.27-35
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• 1998

EAF dust generated from electric arc steelmaking process is classified as "hazardous" materials by tbe environmental regulation because of the existence of water leachable heavy metals such as Fe, Zn, Pb, and Cd. However, Fe and Zn among t the elements in the dust can be recovered to high valuable materials by applying a proper process. Therefore, in order to study t the possibility of recovery of iron from EAF dust, the effect oE carbon content and basicity, of synthesized EAF dust on the reduction rate of iron oxide was studied. Experimental results are as follows: TIle softening and melting temperature of the slag w was illcreased with increasing carbon addition amount [or carbon reduction eqUIvalent. At the carbon addition amount of 100% for carbon reduction equivalent and basicity of 1.7, reduction rate of $Fe_2O$ in the slag was the highest. The reaction order fur reduction of $Fe_2O$ by carbon was nearly first order.

• Korean Journal of Materials Research
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• v.27 no.6
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• pp.325-330
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• 2017

Photoelectron-hole separation efficiency plays an important role in the enhancement of the photocatalytic activity of photocatalysts towards the degradation of organic molecules. In this study, $TiO_2/TiOF_2$ heterostructured composite powders with suitable band structures, which structures are able to separate photoelectron-hole pairs, have been synthesized using a simple and versatile ultrasonic spray pyrolysis process. In addition, their phase volume fractions have been controlled by varying the pyrolysis temperature from $400^{\circ}C$ to $800^{\circ}C$. The structural and optical properties of the synthesized powders have been characterized by X-ray diffraction, scanning electronic microscopy and UV-vis spectroscopy. The powder with a phase volume ratio close to 1, compared with single $TiOF_2$ and other composite powders with different phase volume fractions, was found to have superior photocatalytic activity for the degradation of rhodamine B. This result shows that the $TiO_2/TiOF_2$ heterostructure promotes the separation of the photoinduced electrons and holes and that this powder can be applicable to environmental cleaning applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.128-128
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• 2000

박막의 탄성 특성을 평가하는 방법으로 nano-indentation, Brillouin light scattering measurement, ultrasonic surface wave measurement, bulge test, vibration membrane method 등 여러 가지가 제시되어 왔다. 이러한 방법들은 필름의 두께가 일정 두께 이상이 되어야 정확한 측정이 가능한 방법으로 매우 얇은 박막에서도 탄성특성을 평가할 수 있는 freehang, bridge 방법이 제시되었으며, 이 방법은 간단한 식각 공정을 통해 매우 얇은 박막에도 적용시킬 수 있다는 장점을 가지고 있다. 본 연구에서는 아주 얇은 박막에서도 탄성특성을 평가할 수 있는 freehang 방법을 이용하여 순수한 Diamond-like carbon (DLC) 필름과 Sidl 첨가된 DLC 필름의 탄성 특성을 평가하고자 한다. 실험에서 사용한 필름은 rf-PACVD 장비를 이용하여 증착하였다. 이때 전극과 플라즈마 사이의 바이어스 음전압은 -400 Vb로 합성압력은 10mTorr로 고정하였다. 사용한 반응 가스는 벤젠(C6H6), 그리고 벤젠과 희석된 실렌(SiH4 : H2 = 10 : 90)이며, 희석된 실렌의 첨가량을 조절하여 필름 내에 일정량의 Si을 함유시켰다. 각각의 조건에서 증착시간을 조절하여 필름의 두께를 변화시켰으며, KOH(5.6mol) 용액을 이용하여 습식 식각을 함으로써 freehang을 제작하였다. 이때 식각액에 의한 DLC 필름의 손상은 관찰되지 않았다. 필름의 잔류 응력을 측정하기 위해 200$\pm$10 혹은 100$\pm$5$\mu\textrm{m}$ 두께의 얇은 (100) Si wafer를 5$\times$50 mm2의 strip 형태로 절단하여 사용하였다. 필름의 압축 잔류 응력에 의해 발생한 필름/기판 복합체의 곡률은 laser 반사법과 $\alpha$-step profiler를 이용하여 측정하였으며, 이 결과를 Brenner 등에 유도된 식을 이용하여 잔류 응력을 계산하였다. 또한 제작된 frddhang은 광학 현미경과 전자주사현미경에 의해 관찰되었다. 이렇게 제작된 freehang을 이용하여 필름이 기판에 부착되기 위해 필요한 변형률을 측정하고, 독립적으로 측정된 필름의 잔류 응력을 박막의 응력-변형률 관계식에 적용하여 biaxial elastic modulus, E/(1-v)를 구할 수 있었다. 측정 결과 필름의 잔류 응력과 biaxial elastic modulus는 필름의 두께가 감소함에 따라 감소하는 경향을 나타냈으며, 같은 두께의 필름인 경우, 식각 깊이에 따른 biaxial elastic modulus 의 변화를 통해 최적의 식각 깊이를 알 수 있었다.

• Journal of the Korean Vacuum Society
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• v.18 no.4
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• pp.259-265
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• 2009

We fabricated the field effect transistor using single crystalline ZnO nanowires synthesized by a conventional thermal evaporation method and investigated their basic properties under the various conditions such as ultraviolet irradiation, reducing gas and electrolyte. The typical carrier concentration and mobility of the single crystalline ZnO nanowire with a diameter of 100 nm and length of 5 um were $1.30{\times}10^{18}cm^{-3}$ and $15.6cm^2V^{-1}s^{-1}$, respectively. The current of ZnO nanowire under ultraviolet irradiation significantly increased about 400 times higher as compared to in the darkness. In addition, the ZnO nanowire showed typical sensing characteristics for $H_2$ and CO due to well-known surface reactions and typical current-voltage characteristics under the 0.1 M NaCl electrolyte.