• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.472-473
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• 2006

Maghemite and hematite nanospheres were synthesized by using the Sol-gel technique. The structural properties of these nanosphere powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and pore size distribution. Hematite phase shows crystalline structures. The mean particle size that resulted from BET and XRD analyses were 4.9 nm and 2 nm. It can be seen from transmission electron microscopy that the size of the particles are very small which is in good agreement with the FESEM and the X-ray diffraction. The BET and pore size method were employed for specific surface area determination.

• 펄프종이기술
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• 제41권5호
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• pp.50-58
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• 2009

Periodic variation of local paper structure was evaluated using two-dimensional fast Fourier transform (FFT) and spectral analysis. Since the periodic variation could originate from various sources and have different magnitudes and patterns depending on the origins, a complete analysis of local paper structure properties such as local grammage, local thickness, local apparent density and surface topography was proposed in this study. For a commercial copy paper, the individual periodic patterns for each local structural property were identified by using inverse FFT spectrums of the filtered spectrum. The spectral analysis of newsprint sample provided the period of variation quantitatively, which was useful in comparing the origins of the individual periodic patterns of the local structural properties.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.859-862
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• 2003

Well-aligned multiwall carbon nanotubes (MWCNTs) were prepared at low temperature of 400 $^{\circ}C$ by utilizing a radio frequency plasma-enhanced chemical vapor deposition (rf-PECVD) system. The MWCNTs were treated by an external rf plasma source and an ultra-violet laser in order to modify structural defect of carbon nanotube and to ablate possible contamination on carbon nanotube surface. Structural properties of carbon nanotubes were investigated by using a scanning electron microscopy (SEM), Raman spectroscopy, Fourier transformer Infrared spectroscopy (FTIR) and transmission electron microscope (TEM). In addition, the emission properties of the MWNTs were measured for the application of field emission display (FED) in near future. Various post treatments were found to improve the field emission property of carbon nanotubes.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.56.2-56.2
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• 2010

An improvement in the optical and structural properties of p-GaN was obtained by using antimony (Sb) as a surfactant during p-GaN growth. Two different growth temperatures of p-GaN such as $1030^{\circ}C$ and $900^{\circ}C$ were considered. Keeping the growth conditions for p-GaN constant, Sb was introduced during p-GaN growth while varying the [Sb]/([Ga]+[Mg]) flow ratio. [Sb]/([Ga]+[Mg]) flow ratio will be denoted as SGM ratio for convenience. SGM ratio of 0, 0.015 and 0.03% were considered for high temperature p-GaN growth. SGM ratio of 0, 0.005, 0.01 and 0.02% were considered for low temperature p-GaN growth. The analysis results suggest that using the optimum SGM ratio during p-GaN growth greatly improves the optical and structural properties of the p-GaN.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1383-1386
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• 1997

Dimond-like carbon(DLC) films have been deposited by using both rf plasma-enhanced chemical vapor deposition (PECVD) and filtered cathodic vacuum arc (FCVA) deposition systems. Effects of deposition conditions, such as dc self-bias, $CH_4$ gas pressure, substrate bias, and $N_2$ partial pressure, on the structural and electrical properties of DLC films are examined. The experimental results obtained have also been discussed by considering a theoretical model for film growth.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 연료전지심포지움 2003논문집
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• pp.83-88
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• 2003

PtRu alloy and $PtRu-WO_3$ nanocomposite thin-film electrodes for methanol electrooxidation were fabricated by means of a sputtering method. The structural and electrochemical properties of well-defined PtRu alloy thin-film electrodes were characterized using X-ray diffraction, Rutherford backscattering spectroscopy. X-ray photoelectron spectroscopy, and electrochemical measurements. The alloy thin-film electrodes were classified as follows: Pt-based and Ru-based alloy structure. Based on structural and electrochemical understanding of the PtRu alloy thin-film electrodes, the well-controlled physical and (electro)chemical properties of $PtRu-WO_3$, showed superior specific current to that of a nanosized PtRu alloy catalyst, The homogeneous dispersion of alloy catalyst and well-formed nanophase structure would lead to an excellent catalytic electrode reaction for high-performance fuel cells. In addition, the enhanced catalytic activity in nanocomposite electrode was found to be closely related to proton transfer in tungsten oxide using in-situ electrochemical transmittance measurement.

• Journal of Korean Vacuum Science & Technology
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• 제6권2호
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• pp.67-70
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• 2002

Multi-period low-emissivity (low-e) filters based on [TiO$_2$｜Ti｜Ag｜TiO$_2$] layer structure were designed and fabricated by a RF magnetron sputtering method. Optical, structural, chemical, and electrical properties were investigated with various analytical tools. Interface layers consisting of Ag, Ti, and O were observed next to Ag layers by Rutherford backscattering spectrometry (RBS) analysis. The results show that Ti layers of ~ 1.8 nm protect the Ag layers from oxidation better than those of ~ 1 nm and the optical spectra of the filter with thicker Ti layers are in agreement with the simulated one. The average transmittance of a low-e filter with thicker Ti layers is reduced and the sheet resistance is slightly increased due to the increased Ti thickness.

• Structural Engineering and Mechanics
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• 제89권3호
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• pp.323-334
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• 2024

Physical and chemical factors can cause traditional timber constructions to lose structural integrity. Knowing the dynamic properties of the building components is vital to avoid damage to the buildings from dynamic effects, a subset of physical effects. In this work, spruce and scotch pine wooden beams that had been strengthened in three distinct ways with carbon fiber strengthened polymer (CFRP) were investigated for changes in their dynamic properties. For this, CFRP was used to strengthening unstrengthened wooden beams in the form of bottom confinement, U-shaped confinement, and full confinement after the dynamic parameters of the beams were determined. By using experimental modal analysis with both free-free and fixed-fixed boundary conditions, the beams'initial natural frequencies were identified.

• 대한기계학회논문집A
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• 제36권9호
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• pp.1095-1101
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• 2012

수소를 대량으로 생산하기 위한 원자력수소생산시스템에서 공정열교환기(PHE)는 초고온가스로로 부터 생성된 초고온 열을 화학반응공정으로 전달하는 핵심기기이다. 한국원자력연구원에 구축되어 있는 소형 질소가스루프에서 Hastelloy-X로 제작된 소형 및 중형 PHE 시제품들에 대한 성능시험이 수행되고 있다. 그동안 PHE 시제품에 대한 거시적 고온구조해석은 용접 물성치의 부재로 인해 모재의 물성치만을 사용한 해석이 주로 수행되었으나 본 연구에서는 계장형 압입시험법으로부터 얻은 용접부 기계적 물성치를 이용하여 거시적 고온구조해석을 수행하고 그 결과를 비교, 분석하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.23.1-23.1
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• 2009

ZnO is of great interest for various technological applications ranging from optoelectronics to chemical sensors because of its superior emission, electronic, and chemical properties. In addition, vertically well-aligned ZnO nanorods on large areas with good optical and structural properties are of special interest for the fabrication of electronic and optical nanodevices. To date, several approaches have been proposed for the growth of one-dimensional (1D) ZnO nanostructunres. Several groups have been reported the MOCVD growth of ZnO nanorods with no metal catalysts at $400^{\circ}C$, and fabricated a well-aligned ZnO nanorod array on a PLD prepared ZnO film by using a catalyst-free method. It has been suggested that the synthesis of ZnO nanowires using a template-less/surfactant-free aqueous method. However, despite being a well-established and cost-effective method of thin film deposition, the use of magnetrons puttering to grow ZnO nanorods has not been reported yet. Additionally,magnetron sputtering has the dvantage of producing highly oriented ZnO film sat a relatively low process temperature. Currently, more effort has been concentrated on the synthesis of 1D ZnO nanostructures doped with various metal elements (Al, In, Ga, etc.) to obtain nanostructures with high quality,improved emission properties, and high conductance in functional oxide semiconductors. Among these dopants, Ga-doped ZnO has demonstrated substantial advantages over Al-doped ZnO, including greater resistant to oxidation. Since the covalent bond length of Ga-O ($1.92\;{\AA}$) is nearly equal to that of Zn-O ($1.97\;{\AA}$), high electron mobility and low electrical resistivity are also expected in the Ga-doped ZnO. In this article, we report the successful growth of Ga-doped ZnO nanorods on c-Sapphire substrate without metal catalysts by magnetrons puttering and our investigations of their structural, optical, and field emission properties.