• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.225-228
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• 2002

The adhesion effect between the oxide layer and the metal layer has been studied by RTP anneal. Two types of oxides, BPSG and P-TEOS, were used as a bottom layer under multi-layered metal film. We observe the interface between oxide and metal layer using SEM (scanning electron microscopy), TEM (transmission electron microscopy), AES (auger electron spectroscopy). Adhesion failure was occurred by interfacial reaction between the BPSG oxide and the multi-layered metal film at 650"C RTP anneal. The phosphorus rich layer was observed at interface between BPSG oxide and metal layer by AES and TEM measurements. On the other hand adhesion was a)ways good in the sample used P-TEOS oxide as a bottom layer. We have known that adhesion between BPSG and multi-layered metal film was improved when the sample was annealed below $650^{\circ}C$.TEX>.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.379-382
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• 2019

Synthesis of gold nanoparticles (NPs) made an aqueous environment via the reduction of HAuCl₄ by ascorbic acid (AC) with the surfactant of polyvinylpyrrolidone (PVP). Highly monodisperse gold particles with size ranges from 4 to 20 nm were prepared in high-yield by pH control. The synthesized gold nanoparticles were analyzed for structural and optical properties using transmission electron microscopy (TEM) and UV-vis spectroscopy. In this study, we could reveal that the prepared nanoparticles exhibited efficient surface-enhanced Raman scattering (SERS) properties, and their SERS activities depends on size.

• Polymer(Korea)
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• v.27 no.1
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• pp.17-25
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• 2003

Using atom transfer radical polymerization (ATRP), polystyrene macroinitiators and polystyrene-b-poly(t-butyl acrylate) (PS-b-P(tBA) block copolymers were synthesized by CuBr/PMDETA catalyst system in solution. After hydrolysis, polystyrene-b-poly(acrylic acid), amphiphilic block copolymers, were formed. Subsequent neutralization of polyacid block led to the block ionomers. The molecular weight of the synthesized PS-b-P(tBA) block copolymers was easily-controlled to 5000-10000 and their distributions were less than 1.2. The chemical structures of the synthesized block copolymers were characterized by $^1$H-NMR and FT-IR. In the DSC thermograms, $T_g$ appeared in the vicinity of 100 $^{\circ}C$ because of higher styrene content. In addition, the phase separation of the block ionomers was observed by TEM.

• Korean Journal of Materials Research
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• v.18 no.1
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• pp.51-56
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• 2008

The crystal structures and morphologies of precipitates in $L1_0$-ordered TiAl intermetallics containing nitrogen were investigated by transmission electron microscopy (TEM). Under aging at an approximate temperature of 1073 K after quenching from 1423 K, TiAl hardens appreciably due to the nitride precipitation. TEM observations revealed that needle-like precipitates, which lie only in one direction parallel to the [001] axis of the $L1_0$-TiAl matrix, appear in the matrix preferentially at the dislocations. Selected area electron diffraction (SAED) pattern analyses showed that the needle-shaped precipitate is perovskite-type $Ti_3AlN$ (P-phase). The orientation relationship between the P-phase and the $L1_0$-TiAl matrix was found to be $(001)_P//(001)_{TiAl}\;and\;[010]_P//[010]_{TiAl}$. By aging at higher temperatures or for longer periods at 1073 K, plate-like precipitates of $Ti_2AlN$ (H-phase) with a hexagonal structure formed on the {111} planes of the $L1_0$-TiAl matrix. The orientation relationship between the $Ti_2AlN$ and the $L1_0$-TiAl matrix is $(0001)_H//(111)_{TiAl}\;and\;_H//_{TiAl}$.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.442-444
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• 2018

Recently, we isolated a multidrug-resistant Escherichia coli strain KBN10P04869 from a patient with acute myeloid leukemia. We report the complete genome of this strain which consists of 5,104,264 bp with 4,457 protein-coding genes, 88 tRNAs, and 22 rRNAs, and the co-occurrence of multidrug- resistant genes including $^{bla}CMY-2$, $^{bla}TEM-1$, $^{bla}CTX-M-15$, $^{bla}NDM-5$, and $^{bla}OXA-18$.

• 한국전자현미경학회:학술대회논문집
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• 1993.06a
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• pp.27-27
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• 1993

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.77-82
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• 2011

The surface of $Li[Ni_{0.35}Co_{0.3}Mn_{0.35}]O_2$ cathode was modified by $[Li,La]TiO_3$ coating using pH controlled coating solution. At low pH values (acidic solution), cathode powders, which is oxides, have a positive surface charge, whereas, they have a negative surface charge at high pH values. As a result, their charge could affect the formation of the coating layer on the surface of cathode powder. To determine the optimal pH value, the surface coating of the pristine powder was carried out at various pH values of the coating solution. The surface morphology of coated samples was characterization by SEM and TEM analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the pH of coating solution.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.6
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• pp.639-643
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• 2008

STATEMENT OF PROBLEM: The degree of conversion may influence the ultimate mechanical and physical properties of provisional crown and fixed partial denture materials. The high levels of the unreacted residual monomer may cause deleterious effect on the properties. PURPOSE: The purpose of this study was to measure the degree of conversion of bis-acrylic based provisional crown and fixed partial denture materials by using an infrared spectroscopic method. MATERIAL AND METHODS: Chemically activated three bis-acrylic based provisional crown and fixed partial denture materials, LuxaTemp [DMG, Hamburg, Germany], fast set TemPhase [Kerr, Orange, CA, USA] and Protemp 3 Garant [3M-ESPE, St Paul, MN, USA], were investigated by Fourier transform infrared spectrometry (FTIR). The FTIR spectra of the materials tested were immediately obtained after mixing. The specimens were stored under dry conditions and at $23^{\circ}C$ for 24 hours, and then the spectra of the materials were also obtained. The degree of conversion (%) was calculated from the spectrum of the absorbance between the aliphatic double bond at 1637 $cm^{-1}$ and the aromatic double bond at 1608 $cm^{-1}$ using the baseline method. The data were statistically analyzed using one-way ANOVA and the multiple comparison Scheffe test at the significance level of 0.05. RESULTS: The mean value and standard deviation of the degree of conversion were 52.5 % ${\pm}$ 1.1 %, 50.3 % ${\pm}$ 0.8 %, and 42.3 % ${\pm}$ 4.9 % for LuxaTemp, Protemp 3 Garant and fast set TemPhase, respectively. There was no significant difference between LuxaTemp and Protemp 3 Garant, whereas there was a statistically difference between Protemp 3 Garant and fast set TemPhase, and LuxaTemp and fast set TemPhase (P < .05). CONCLUSION: The degree of conversion of fast set TemPhase was significantly lower than those of the others. The degree of conversion may be correlated with the rate of polymerization.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.22-23
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• 2002

Titanium은 높은 강도, 낮은 밀도, 부식에 대한 저항 등, 타 금속에 비해 월등히 뛰어난 성질을 가지고 있기 때문에 산업 전반에 거쳐 그 응용이 크게 증가하고 있으며, 특히 고온에서의 응용이 중요성을 띠게 됨에 따라 고온으로의 상전이 관계에 따른 구조적 규명이 필요하다. 순수한 titanium은 상온에서 조밀충진 육방정계의 α-상구조(a=2.953Å, c=4.683 Å, P6₃/mmc)를 이루고 있으나, 대략 880℃ 이상에서는 β-상의 체심입방정계 (a=3.320Å, Im3m)로 상전이가 되는 것으로 알려져 있다. 이에 대한 대부분의 연구가 kinetics와 thermodynamics에 관련되어 있으며, TEM을 이용한 직접가열실험은 거의 전무한 상태이다. 본 실험에서는 TEM 직접가열을 통하여 titanium의 고온에서의 상전이와 가열시 발생할 수 있는 산화층 형성을 연구하였다. TEM 시편은 순도 99.94％의 titanium foil(Alfa Aesar, ＃00360, 0.025mm thick)를 이용하였고, 분석 장비로는 에너지여과 기능이 있는 TEM(EM912 Omega, Carl Zeiss)과 Gatan사의 double-tilt heating holder를 사용하였다. Titanium의 상전이를 관찰하기 위해 900℃ 까지 분당 10℃ 의 속도로 가열을 하였다. 통계적 분석 오차를 줄이기 위해 서로 다른 4군데의 관찰영역을 선택하여, 상온 - 600℃ - 900℃ - 상온의 단계별로 회절패턴을 관찰 및 기록하였고, 발생 가능한 산화에 대해서는 동일한 장비를 사용하여 EDS 분석을 하였다. 상온에서의 서로 다른 영역의 회절패턴들은 결함의 존재에 상관없이, 온도가 증가함에 따라 그 결함수가 증가하게 된다. 특히 600℃ 에서는 쌍정과 관련된 회절점들이 본래의 회절점 주위에 형성되어있지만, 각 면들의 격자상수의 변화는 나타나지 않았다. 그러나 900℃ 에서는 쌍정에 의한 회절점의 수가 증가하며, 회절점 사이에 발달한 뚜렷한 막대모양의 강도분포와 격자상수의 변화를 관찰할 수 있었다. 다시 상온으로 냉각시킨 후 관찰한 각각의 회절패턴에서는 격자 상수의 감소와 함께 900℃에 보여진 막대 모양의 강도분포와 쌍정에 의한 회절점들이 여전히 남아있었다. EDS분석 결과 가열 실험을 통해 시편이 열적 산화가 되어 있음을 확인 할 수 있었다. 순수한 titanium의 α-상에서 β-상으로의 상전이를 파악할 수 있는 격자상수의 변화자체는 매우 작은 값이기 때문에 상온과 900℃ 에서 기록된 전자회절패턴 상에서의 면간거리와 면간각도의 측정만으로는 상전이 여부를 명확히 구별할 수 없었다. 그러나, 결함에 의한 상변화가 900℃ 에서 심하게 관찰되어지는 것은 상전이와 관계가 있는 것으로 볼 수 있다. 고온에서 상온으로의 가역적 반응을 관찰할 수 없었던 이유는 열적산화로 생긴 산화층의 산소원자들이 고온의 상전이 과정 중에 Ti 원자와 반응이 일어나 TiO/sub X/ 구조로 전이되었기 때문으로 추정하고 있다.

• Journal of Ocean Engineering and Technology
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• v.20 no.2 s.69
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• pp.59-65
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• 2006

Steel, as a reinforcing mechanism in concrete, provides the tensile strength that is lacking in concrete, alone, and the high alkaline environment (pH 12.5) in concrete offers satisfactory protection against most corrosion of the steel. However, the corrosion of reinforcing steel in concrete can occur by chloride attack or carbonation, and it can cause a loss of integrity a section and concrete failure through cracking and spalling. In this study, a transient electro magnetic method (TEM) of a nondestructive technique is adapted to study the measuring method of steel corrosion in mortar. The sensor was made of an enameled wire, with a diameter of 0.25mm and anacril. He sensor configuration used was a coincident loop type. The secondary electro motive force (2nd EMF) was measured with SIROTEMIII, which equipped the accelerator. The accelerator allowsthe transmitter to turn off approximately $10\sim15$ times faster than normal. The high-resolution time series, used for very shallow or a high resistivity investigation was selected. After steels were corroded by the salt spray, during 4, 8, 15 and 25 days, they were embedded in mortar. The content results acquired in this study are as follows. The variation of the secondary electro motive force (2nd EMF) was shown by the change of steel surface with different corrosion time steel. It was confirmed that measurement of steel corrosion in mortar by a transient electro-magnetic method (TEM) can be possible.