• Fire Science and Engineering
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• v.33 no.6
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• pp.114-119
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• 2019

We found metallic migration phenomena at the fire scene in Printed circuit board (PCB) of LED light equipment which are commonly used. Accordingly we did this study. In order to generate rapidly metallic migration, we experiment the water drop test under low voltage (3.0 V) and a small amount of water condition. As a results of our experiment, we saw the growth of metallic migration of Copper and checked directly short of the PCB between isolated two poles by Cu migration. Finally we saw the shape of dendrite pattern by Cu migration using Scanning electron microscope (SEM) and analyzed that components via Energy dispersive Spectrometer (EDS).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.3
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• pp.294-300
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• 2015

Objectives: The aim of this study is to identify physicochemical properties such as chemical composition, size, shape and crystal structure of powder byproducts generated from a metallization process and its 1st scrubber in the semiconductor industry. Methods: Powder samples were collected from inner chambers during maintenance of the W-plug process equipment (using tungsten hexafluoride as a precursor material) and its 1st scrubber. The chemical composition, size and shape of the powder particles were determined by field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) equipped with an energy dispersive spectroscope (EDS). The crystal structure of the powders was analyzed by X-ray diffraction (XRD). Results: From the SEM-EDS and TEM-EDS analyses, O and W were mainly detected, which indicates the powder byproducts are tungsten trioxide ($WO_3$), whereas Al, F and Ti were detected as low peaks. The powder particles were spherical and nearly spherical, and the particle size collected from the process equipment and its 1st scrubber showed 10-20 nm (agglomerates: 55-90 nm) and 16-20 nm (agglomerates: 80-120 nm) as primary particles, respectively. The XRD patterns of the yellow powder byproducts exhibit five peaks at $23.8^{\circ}$ $33.9^{\circ}$ $41.74^{\circ}$ $48.86^{\circ}$ and $54.78^{\circ}$ which correspond to the (200), (220), (222), (400), and (420) planes of cubic $WO_3$. Conclusions: We elucidated the physicochemical characteristics of the powder byproducts collected from W-plug process equipment and its 1st scrubber. This study should provide useful information for the development of alternative strategies to improve the working environment and workers' health.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.39.1-39.1
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• 2009

NiTi alloy is widely used innumerous biomedical applications (orthodontics, cardiovascular, orthopaedics, etc.) for its distinctive thermomechanical and mechanical properties such as shape memory effect, super elasticity, low elastic modulus and high damping capacity. However, NiTi alloy is still a controversial biomaterial because of its high Ni content which can trigger the risk of allergy and adverse reactions when Ni ion releases into the human body. In order to improve the corrosion resistance of the TiNi alloy and suppress the release of Ni ions, many surface modification techniques have been employed in previous literature such as thermal oxidation, laser surface treatment, sol-gel method, anodic oxidation and electrochemical methods. In this paper, the NiTi was electrochemically etched in various electrolytes to modify surface. The microstructure, element distribution, phase composition and roughness of the surface were investigatedby scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry(EDS), X-ray diffractometry (XRD) and atomic force microscopy (AFM). Systematic controlling of nano and submicron surface features was achieved by altered density of hydro fluidic acid in etchant solution. Nanoscale surface topography, such as, pore density, pore width, pore height, surface roughness and surface tension were extensively analyzed as systematical variables.Importantly, bone forming cell, osteoblast adhesion was increased in high density of hydro fluidic treated surface structures, i.e., in greater nanoscale surface roughness and in high surface areas through increasing pore densities.All results delineate the importance of surface topography parameter (pores) inNiTi to increase the biocompatibility of NiTi in identical chemistry which is crucial factor for determining biomaterials.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.743-748
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• 2010

Boron nitride (BN) and carbon nitride (CN) films, which have relatively low work functions and commonly exhibit negative electron affinity behaviors, were coated on carbon nanotubes (CNTs) by magnetron sputtering. The CNTs were directly grown on metal-tip (tungsten, approximately 500nm in diameter at the summit part) substrates by inductively coupled plasma-chemical vapor deposition (ICP-CVD). The variations in the morphology and microstructure of CNTs due to coating of the BN and CN films were analyzed by field-emission scanning electron microscopy (FE-SEM). The energy dispersive x-ray (EDX) spectroscopy and Raman spectroscopy were used to identify the existence of the coated layers (CN and BN) on CNTs. The electron-emission properties of the BN-coated and CN-coated CNT-emitters were characterized using a high-vacuum field emission measurement system, in terms of their maximum emission currents ($I_{max}$) at 1kV and turn-on voltage ($V_{on}$) for approaching $1{\mu}A$. The results showed that the $I_{max}$ current was significantly increased and the $V_{on}$ voltage were remarkably reduced by the coating of CN or BN films. The measured values of $I_{max}-V_{on}$ were as follows; $176{\mu}A$-500V for the 5nm CN-coated emitter and $289{\mu}A$-540V for the 2nm BN-coated emitter, respectively, while the $I_{max}-V_{on}$ of the as-grown (i.e., uncoated) emitter was $134{\mu}A$-620V. In addition, the CNT emitters coated with thin CN or BN films also showed much better long-term (up to 25h) stability behaviors in electron emission, as compared with the conventional CNT emitter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.484-484
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• 2009

반도체 소자가 차세대 초미세 공정 기술 도입의 가속화를 통해 고속화 및 고집적화 되어 감에 따라 나노 (nano) 크기의 회로 선폭 미세화를 극복하고자 최적의 CMP (chemical mechanical polishing) 공정이 요구되어지고 있다. 최근, 금속배선공정에서 높은 전도율과 재료의 값이 싸다는 이유로 Cu를 사용하였으나, 디바이스의 구조적 특성을 유지하기 위해 높은 압력으로 인한 새로운 다공성 막(low-k)의 파괴와, 디싱과 에로젼 현상으로 인한 문제점이 발생하게 되었다. 이러한 문제점을 해결 하고자 본 논문에서는 Cu의 ECMP 적용을 위해 LSV (Linear sweep voltammetry)법을 통하여 알칼리 성문인 $NaNO_3$ 전해액과 산성성분인 $HNO_3$ 전해액의 전압 활성화에 의한 active, passive, transient, trans-passive 영역을 I-V 특성 곡선을 통해 알아보았고, 알칼리와 산성 성분의 전해액이 Cu 표면에 미치는 영향을 SEM (Scanning electron microscopy), EDS (Energy Dispersive Spectroscopy), XRD(X-ray Diffraction)를 통하여 전기화학적 특성을 비교 분석하였다.

• Electrical & Electronic Materials
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• v.16 no.9
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• pp.64.2-65
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• 2003

A 4 nm layer of ZrOx (targeted x-2) was deposited on an interfacial layer(IL) of native oxide (SiO, t∼1.2 nm) surface on 200 mm Si wafers by a manufacturable atomic layer chemical vapor deposition technique at 30$0^{\circ}C$. Some as-deposited layers were subjected to a post-deposition, rapid thermal annealing at $700^{\circ}C$ for 5 min in flowing oxygen at atmospheric pressure. The experimental x-ray diffraction, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and high-resolution parallel electron energy loss spectroscopy results showed that a multiphase and heterogeneous structure evolved, which we call the Zr-O/IL/Si stack. The as-deposited Zr-O layer was amorphous $ZrO_2$-rich Zr silicate containing about 15% by volume of embedded $ZrO_2$ nanocrystals, which transformed to a glass nanoceramic (with over 90% by volume of predominantly tetragonal-$ZrO_2$(t-$ZrO_2$) and monoclinic-$ZrO_2$(m-$ZrO_2$) nanocrystals) upon annealing. The formation of disordered amorphous regions within some of the nanocrystals, as well as crystalline regions with defects, probably gave rise to lattice strains and deformations. The interfacial layer (IL) was partitioned into an upper Si $o_2$-rich Zr silicate and the lower $SiO_{x}$. The latter was sub-toichiometric and the average oxidation state increased from Si0.86$^{＋}$ in $SiO_{0.43}$ (as-deposited) to Si1.32$^{＋}$ in $SiO_{0.66}$ (annealed). This high oxygen deficiency in $SiO_{x}$ indicative of the low mobility of oxidizing specie in the Zr-O layer. The stacks were characterized for their dielectric properties in the Pt/{Zr-O/IL}/Si metal oxide-semiconductor capacitor(MOSCAP) configuration. The measured equivalent oxide thickness (EOT) was not consistent with the calculated EOT using a bilayer model of $ZrO_2$ and $SiO_2$, and the capacitance in accumulation (and therefore, EOT and kZr-O) was frequency dispersive, trends well documented in literature. This behavior is qualitatively explained in terms of the multi-layer nanostructure and nanochemistry that evolves.ves.ves.

• Composites Research
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• v.17 no.1
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• pp.10-17
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• 2004

In this work, the blend system prepared from epoky(DGEBA)/polymethylmethacrylate(PMMA) was investigated in thermal and mechanical interfacial property measurements. The thermal properties were carried out by DSC, DMA, and TGA measurements. Also, the surface free energy and fracture toughness were determined by contact angle and critical stress intensity factor($K_{IC}$), respectively. And the fracture surface was observed by SEM after $K_{IC}$ tests. As experimental results, the curing temperature and glass transition temperature were slightly increased in addition of PMMA. Surface free energy of the blends showed an improved value at low contents of PMMA which could be attributed to the both increasings of London dispersive and polar components. From measurement of $K_{IC}$ of the blends, the highest value was found at 5 phr. This was due to the increasing of compatibility or physical interaction in macromolecular chains between DGEBA and PMMA of the blends.

• Analytical Science and Technology
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• v.9 no.1
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• pp.20-25
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• 1996

Trace levels of uranium and thorium in geologic samples are determined rapidly by a direct wavelength-dispersive X-ray fluorescence method. Relative intensity of scattered tube radiation was used as an internal standard to compensate for variations in instrumental operating characteristics. U and Th can be determined within a precision of ${\pm}10%$ and accuracy of ${\pm}15%$ or less with measuring times of 50 seconds for Th and 400 seconds for U, respectively. The results of XRF analysis were in good agreement with those of other methods such as nutron activation analysis and inductively coupled plasma atomic emission spectrometry.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.94-94
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• 2013

The Cr-Zr-N films have much improved mechanical properties and very smooth surface roughness. However, in spite of their outstanding properties, the Cr-Zr-N coatings revealed their mechanical properties deteriorated severely with increasing Zr content at $500^{\circ}C$ ecause of very rapid oxidation. Recently oxynitride films have been widely studied due to their excellent unique mechanical properties and oxidation resistance. In this work, CrZr-O-N films with various O contents were synthesized by unbalanced magnetron sputtering with Cr-Zr segment targets (Cr:Zr volume ratios is 1：1) and all films were prepared in a nitrogen rich mixture of N2 and O2. Characteristics such as crystalline structure, hardness and chemical composition as a function of the O content were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), microhardness testing system and energy dispersive spectroscopy (EDS). Results showed that the thin films had dense and compact microstructure as O content in the films increases. The microstructure of the thin films consisted of mainly crystalline Cr (Zr)N phase and Cr2O3 phase. The maximum hardness and elastic modulus of the films was measured to be approximately 33.2 GPa and 280.6 GPa from the films with low content of O elements. Detailed experimental results will be presented.

• Journal of Conservation Science
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• v.16 s.16
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• pp.104-109
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• 2004

The characteristics and composition of the ancient glasses excavated at Songdong-ri, Sangju, Kyongsangbuk-do were analyzed using Scanning Electron Microscope attached with Energy Dispersive Spectrometer. As the results, the glass beads of Songdong-ri showed that there were changed the composition, the color and types according to the periods. There were appeared potash and soda glass group at A.D.4 century and potash and mixed alkali glass group at A.D. 17 century. The potash glasses of A.D. 4c. were colored blue and contained low $Al_2O_3$ and CaO composition as below $5\%$. The soda glasses of This period were colored blue and red, and contained $Al_2O_3$ composition as upper $5\%$. But the potash glasses of A.D.17c. showed the transparent yellow color and considerably higher CaO, $11.7\%$. 'Coil glasses' typed unique were colored yellow-brown, Cu-blue and colorless, were classified the mixed alkali glass as upper $5\%\;of\;Na_2O\;and\;K_2O$. The composition of coil glasses were presented first at this study.