• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.756-759
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• 2002

Nanoparticles of titanium dioxide$(TiO_2)$ were prepared by photochemical synthesis. Surface structure, morphology and particle size of $TiO_2$ thin films were investigated by UV-VIS spectrophotometer, scanning electron microscopy(SEM) and transmission electron microscopy(TEM). All process was prepared at room temperature. The absorption peak of the films was showed at 360nm and $TiO_2$ nanopaticle size was observed at about 20~30nm. Electron diffraction ring patterns of $TiO_2$ nanoparticles and crystallographic spacing were observed by TEM. As a result, crystallographic spacing was about 3.6A in HR-TEM micrographs.

• 대한치과기공학회지
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• 제25권1호
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• pp.21-28
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• 2003

The purpose of this study was to process bio-active glass ceramic composite, reinforced with sapphire fibers, by hot press. Also to study the interface of the matrix and the sapphire fiber, and the mechanical properties. Glass raw materials melted in Pt crucible at 1300$^{\circ}C$ during 3.5 hours. The melt was crushed in ball mill and then crushed material, ground and sieved to $<40{\beta}{\mu}m$. Sapphire fibers cut (30mm) and aligned. Powder and fibers hot pressed. The micrographs show good bonding between the matrix and the fiber and no porosity in the glass matrix. This means ideal fracture phenomena. Glass is fractured before the fiber. This is indication of good fracture strength. EDXS showing aluminum rich phase and crystalline phase. Bright field image of the matrix showing crystalline phase. Also diffraction pattern of TEM showing the crystalline phase and more than one phase. Strength of the samples was determined by 3 point bend testing. Strength of the 10vol% sample was approximately 69MPa, while strength of the control sample is 35MPa. Conclusions through this study as follow: 1. Micrographs show no porosity in the glass matrix and the interface. 2. The interface between the fiber and the glass matrix show no gaps. 3. Fracture of the glass indicates characteristic fiber-matrix separation. 4. Presence of crystalline phase at high processing temperature. 5. Sapphire is compatible with bioactive glass.

• Bulletin of the Korean Chemical Society
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• 제26권1호
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• pp.107-114
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• 2005

Molecular aggregates of surfactant molecules consisting of one or more bilayers arranged in a hollow, closed, usually spherical geometry are termed “esicles”or “iposomes” In recent years it has been found that in certain systems the vesicular structure forms spontaneously and is long lived, and it has been suggested that these structures may in fact constitute the equilibrium state in these cases (as is true of micelles) This paper deals with the mixed CMC, vesicles, phase behavior, phase transition, geometrical structure, their formation and characterization in the aqueous solutions of mixed cationic/anionic surfactants systems. TEM micrographs revealed that the vesicles were of spherical shape and that their size was of around 180 nm. The zeta potentials are positive at CGS1-rich regions and negative at SLES-rich regions. In the region where SLES/CGS1 (6/4), the zeta potentials are very small, implying that the vesicles at this surfactant ratio may be less stable. At other surfactant ratios, the vesicles are thought to be stable, supported by large absolute values of zeta potentials and little change in UV absorbance for several months.

• 한국분말재료학회지
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• 제5권3호
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• pp.192-198
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• 1998

Microstructure and mechanical properties were examined on rapidly solidified Al-8wt%Fe alloy. High temperature strength test was also undertaken, and it is shown that the refinement in microstructure resulting from extremely rapid cooling rates gives rise to improved high temperature strength, but the elongation to fracture of this material decreases with increasing temperature, particularly in the temperature range up to 30$0^{\circ}C$. Specimens heat-treated for 100 hrs were analyzed with TEM micrographs to understand the thermal stability of this material.

• 한국자기학회지
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• 제5권2호
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• pp.134-139
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• 1995

DC magnetron 스파터링 방법으로 $(Co_{93}Cr_{7})-P-Ni$ 계 수평 자기 기록용 박막을 제조하였다. $(Co_{93}Cr_{7})-P-Ni$ 의사 삼원계(pseudo-ternary) 박막의 Ni 및 P의 함량 변황 따른 자기적 특성의 변화를 조사하였다. 박막의 조성을 조절함으로써 최대 1500 Oe의 보자력을 얻을 수 있었다. P 첨가에 따른 보자력 향상의 원인으로는 면내 이방성(in-plane anisotropy) 향상, 입자 크기의 변화, P 성분의 입계편석에 따른 입자간의 decoupling 등을 들 수 있다. 또한 TEM으로 미세 구조를 관찰한 결과 P 가 첨가되면 입자의 크기가 작아지면서 입자간의 자기적 decoupling이 일어남을 알 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제35권2호
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• pp.9-15
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• 2007

A comparative study of the structure and organization of the primary and secondary walls in different types of tropical plant waste fibers was carried out using transmission electron microscopy (TEM). The thickness of each layer was also measured using Image Analyzer. TEM micrographs haveconfirmed that cell wall structure of all six types of tropical plant waste fibers (empty fruit bunch, oil palm frond, oil palm trunk, coir, banana stem and pineapple leaf) has the same ultrastructure with wood fibre. The fibers consisted of middle lamella, primary and thick secondary wall with different thickness for different types of fibers. The secondary wall was differentiated into a $S_1$ layer, a unique multi-lamellae $S_2$ layer, and $S_3$ layer.

• 한국세라믹학회지
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• 제45권10호
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• pp.573-578
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• 2008

In the preparation of hydroxyapatite(HAp)/gelatin(GEL) nanocomposite, GEL matrix was modified by the introduction of chondroitin sulfate(ChS) to obtain a strongly organized composite body. The formation reaction of the HAp/GEL-ChS nanocomposite was then investigated via XRD, DT/TGA, FT-IR, TEM and SEM. The organic-inorganic interaction between HAp nanocrystallites and GEL molecules was confirmed from DT/TGA and FT-IR. According to the DT/TGA results, the exothermal temperature zone between 300 and $550^{\circ}C$ showed an additional peak temperature that indicated the decomposition of the combined organics of the GEL and ChS. From the FT-IR analysis, calcium phosphate(Ca-P) was covalently bound with the GEL macromolecules modified by ChS. From TEM and ED, the matrix of the GEL-ChS molecules was mineralized by HAp nanocrystallites and the dense dried nanocomposite body was confirmed from SEM micrographs.

• Bulletin of the Korean Chemical Society
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• 제6권5호
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• pp.304-308
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• 1985

Morphological structure of tin oxide thin films was examined by transmission electron microscopy. TEM samples were prepared by chemical etching in hydrogen fluoride solution: firstly floating for 2-3 minutes in acid solution, then suspending on water found to be useful for the preparation of TEM samples. Electron micrographs showed the size of grains of the tin oxide crystal was dependent upon the temperature of the film preparation. Dopant concentration and heating time also influence the grain size. The resistivity of tin oxide material was explained by grain size and grain boundaries in a limited temperature and dopant concentration ranges.

• 한국표면공학회지
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• 제32권3호
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• pp.467-471
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• 1999

BN films were grown on silicon (l00) substrate by magnetically enhanced activated reactive evaporation (ME-ARE) with pulsed DC power instead of r.f. for substrate biasing. The deposited films were analyzed using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). FTIR results show that the intensity of absorption band of $sp^2$ bond of BN decreased and that of $sp^3$ bond of c-BN increased with increasing pulsed DC bias voltage applied to substrate. The initially grown layer at the interface was observed by TEM and considered to be of$ sp^2$-bonded BN. The cross-sectional and planar TEM micrographs show that the upper layer on the initial layer was the single phase c-BN. It is concluded that cubic boron nitride films could be synthesized by ME-ARE process with pulsed DC biasing.

• 한국표면공학회지
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• 제41권5호
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• pp.194-198
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• 2008

Several methods for improving dispersion of carbon nanotubes (CNTs) have been investigated. CNTs modified by acids and hydrogen peroxide ($H_2O_2$) showed improved dispersion. From SEM micrographs and photos of dispersion, CNTs modified with nitric acid and $H_2O_2$, showed no agglomeration in solution even standing for 4 months, which means successfully improved dispersion property. TEM micrographs of surface modified single CNT treated with 69% $HNO_3$ in boiling acid solution as the optimum method were obtained. For confirmation of CNTs' application to EDLC electrode materials, characteristics of EDLC have been analyzed by cyclic voltammetry curve, specific capacitance of unit cell, electrode discharge curves and AC impedance curve. From the results, it could be confirmed that electrochemical properties of CNTs were enhanced after surface modification with 69% $HNO_3$ acid treatment.