• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.180-185
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• 2000

Nano crystalline or non-crystalline particles have been widely used in various industrial area, such as ceramics, catalysis, electronics, metallurgy and optic device. In all applications, synthesizing the particles as small as possible and controlling the crystalline phase according to its purpose are necessary for the enhancement of processing performance. In some cases, non-agglomerated particles may be necessary for solving the packing problems. This motivates our attempt of controlling size, morphology, phase of nano titania and silica particles. If one can enhance sintering rate of small aggregates independently of collision rate, one may expect that original aggregates can be changed into volume equivalent spheres and thereby the decrease of collision frequency due to the change leads to much smaller rate of growth of the particles. This is the basic idea of our control strategy.

• Advances in materials Research
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• 제8권3호
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• pp.179-196
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• 2019

This paper researches static and dynamic bending behaviors of a crystalline nano-size shell having pores and grains in the framework of strain gradient elasticity. Thus, the nanoshell is made of a multi-phase porous material for which all material properties on dependent on the size of grains. Also, in order to take into account small size effects much accurately, the surface energies related to grains and pores have been considered. In order to take into account all aforementioned factors, a micro-mechanical procedure has been applied for describing material properties of the nanoshell. A numerical trend is implemented to solve the governing equations and derive static and dynamic deflections. It will be proved that the static and dynamic deflections of the crystalline nanoshell rely on pore size, grain size, pore percentage, load location and strain gradient coefficient.

• Applied Microscopy
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• 제39권4호
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• pp.341-348
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• 2009

본 연구에서는 평균 입자크기가 100 nm인 $BaTiO_3$ 나노 결정체의 결정 구조를 전자회절을 이용하여 분석하였다. 전자회절을 이용하여 구조분석을 수행하기 위해 PED 장치의 실험인자를 보정한 후, PED와 일반적인 SAED를 이용하여 전자회절도형을 획득하여 비교 분석을 수행하였다. $BaTiO_3$ 나노 결정체에 대해 PED를 이용한 구조분석을 수행한 결과, $BaTiO_3$ 나노입자는 상온에서 입방정계와 정방정계의 구조가 혼합되어 존재함을 알 수 있었다. 또한 이론적 계산을 통해 두 상이 혼재된 $BaTiO_3$ 나노입자는 입방정계의 구조가 약 8.5nm의 표면을 형성하고 있는 coreshell 구조를 이루고 있음을 예측할 수 있었다. 이러한 $BaTiO_3$ 나노입자에 대한 입방정계와 정방정계 구조의 각각의 격자상수는 a=3.999${\AA}$과 a=3.999${\AA}$, c=4.022${\AA}$이었다. 이와 같이 일반적인 SAED에 비해 뛰어난 공간분해능과 다중산란 효과를 억제할 수 있는 PED 기법은 복합 나노 구조체의 결정구조분석에 보다 유용한 분석 기술로 활용할 수 있을 것으로 기대된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
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• pp.3-6
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• 2002

Effect of Ag additive element on microstructure of $Fe_{87-x}Zr_7B_6Ag_x$, magnetic thin films on Si(001) substrates has been investigated using Transmission Electron Microscopy(TEM) and X-ray Diffraction(XRD). All samples with additive Ag element were made by DC-sputtering and subjected to annealing treatments of $300^{\circ}C{\siim}600^{\circ}C$ for 1 hr. TEM and XRD showed that perfectly amorphous state in Ag-free Fe-based films was observed in as-deposited condition. The as-deposited Fe-based films with the presence of Ag constituent have a mixture of Fe-based amorphous and nano-sized Ag crystalline phases. In this case, additive element, Ag was soluted into Fe-based matrix. With the increase in additive element, Ag, insoluble nano-crystalline Ag particles were dispersed in the Fe-based amorphous matrix. Crystallization of Fe-based amorphous phase in the matrix of $Fe_{82}Zr_7B_6Ag_5$ thin films occurred at an annealing temperature of $400^{\circ}C$. Upon annealing, the amorphous-Ag crystalline state of Fe-Zr-B-Ag films was transformed into the mixture of Ag crystalline phase + Fe-based amorphous phase + ${\alpha}$-Fe cluster followed by the crystallization process of ${\alpha}$-Fe nanocrystalline + Ag crystalline phases.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2005년도 동계학술연구발표회 및 2차 아시안포럼
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• pp.208-208
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• 2005

• 한국재료학회지
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• 제12권10호
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• pp.809-813
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• 2002

Commercial nano crystalline $TiO_2$ powders were used to characterize photocatalyst, using thermal spray coating technique. The microstructure of coating layers were examined by SEM, FE-SEM and TEM. Also the cross sectional areas of TiO$_2$ coating layers were observed by SEM. The phases were analyzed by X-ray diffraction methed. Surface roughness and hardness were measured. It was found that phase transformation from anatase to rutile occurred, and the melted splats are all rutile, and unmeted nano particles were anatase. These unmelted anatase phase may enhance te play a role of photocatalyst.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.203-203
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• 2010

Nano-crystalline Si thin films were deposited on polymer and glass by inductively coupled plasma (ICP) - assisted RF magnetron sputtering at low temperature in an argon and hydrogen atmosphere. Internal ICP coil was installed to increase hydrogen atoms dissociated by the induced magnetic field near the inlet of the working gases. The microstructure of deposited films was investigated with XRD, Raman spectroscopy and TEM. The crystalline volume fraction of the deposited films on polymer was about 70% at magnetron RF power of 600W and ICP RF power of 500W. Crystalline volume fraction was decreased slightly with increasing magnetron RF power due to thermal damage by ion bombardment. The diffraction peak consists of two peaks at $28.18^{\circ}$ and $47.10^{\circ}\;2{\theta}$ at magnetron RF power of 600W and ICP RF power of 500W, which correspond to the (111), (220) planes of crystalline Si, respectively. As magnetron power increase, (220) peak disappeared and a dominant diffraction plane was (111). In case of deposited films on glass, the diffraction peak consists of three peaks, which correspond to the (111), (220) and (311). As the substrate temperature increase, dominant diffraction plane was (220) and the thickness of incubation (amorphous) layer was decreased.

• Current Photovoltaic Research
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• 제11권4호
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• pp.114-117
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• 2023

Transparent Photovoltaic (PV) modules have recently been in the spotlight because they can be applied to buildings and vehicles. However, crystalline silicon (c-Si) solar modules, which account for about 90% of the PV module market, have the disadvantage of applying transparent PV modules due to their unique opacity. Recently, a see-through type PV module using a crystalline silicon solar strap has been developed. However, there is a problem due to a decrease in aesthetics due to the metal ribbon in the center of the see-through type PV module and difficulty bonding the metal ribbon due to the low voltage output of the strap. In this study, to solve this problem, we developed a fabrication process of series connected c-Si solar strap cells using the c-Si solar cells. We succeeded in fabricating a series connected strap with a width of 2-10 mm, and we plan to manufacture an aesthetic see-through type c-Si PV module.

• Advances in nano research
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• 제3권2호
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• pp.81-96
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• 2015

Octahedral shaped single crystalline undoped and Ga-doped indium oxide nano-and microcrystals were fabricated using vapor-solid growth process. Effects of Ga doping on the crystallinity, defect structure, and optical properties of the nano-/microstructures have been studied using scanning electron microscopy, microRaman spectroscopy, transmission electron microscopy and cathodoluminescence spectroscopy. It has been observed that incorporation of Ga does not affect the morphology of $In_2O_3$ structures due to its smaller ionic radius, and similar oxidation state as that of In. However, incorporation of Ga in high concentration (~3.31 atom %) causes lattice compression, reduces optical band gap and defect induced CL emissions of $In_2O_3$ nano-/microcrystals. The single crystalline Ga-doped, $In_2O_3$ nano-/microcrystals with low defect contents are promising for optoelectronic applications.

• 한국재료학회지
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• 제21권8호
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• pp.415-418
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• 2011

Tin (IV) dioxide ($SnO_2$) has attracted much attention due to its potential scientific significance and technological applications. $SnO_2$ nanoparticles were prepared under low temperature and pressure conditions via precipitation from a 0.1 M $SnCl_4{\cdot}5H_2O$ solution by slowly adding $NH_4OH$ while rapidly stirring the solution. $SnO_2$ nanoparticles were obtained from the reaction in the temperature range from 130 to $250^{\circ}C$ during 6 h. The microstructure and phase of the synthesized tin oxide particles were studied using XRD and TEM analyses. The average crystalline sizes of the synthesized $SnO_2$ particles were from 5 to 20 nm and they had a narrow distribution. The average crystalline size of the synthesized particles increased as the reaction temperature increased. The crystalline size of the synthesized tin oxide particles decreased with increases in the pH value. The X-ray analysis showed that the synthesized particles were crystalline, and the SAED patterns also indicate that the synthesized $SnO_2$ nanoparticles were crystalline. Furthermore, the morphology of the synthesized $SnO_2$ nanoparticles was as a function of the reaction temperature. The effects of the synthesis parameters, such as the pH condition and reaction temperature, are also discussed.