• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.63-70
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• 2004

The structural, electrical properties of $(Ba, Sr)TiO_3[BSTO]/RuO_2$ thin films were examined by the addition of amorphous BSTO layer between crystlline BSTO film and $RuO_2$ substrate. We prepared BSTO films with double-layered structure, that is, amorphous layers deposited at $60^{\circ}C$ and crystalline films. Crystalline films were prepared at 550 on amorphous BSTO layer. The thickness of the amorphous layers was varied from 0 to 170 nm. During the deposition of crystalline films, the crystallization of the amorphous layers occurred and the structure was changed to circular while crystalline BSTO films showed columnar structure. Due to insufficient annealing effect, amorphous BSTO phase was observed when the thickness of the amorphous layers exceeded 30 nm. Amorphous BSTO layer could also prevent the formation of oxygen deficient region in $RuO_2$ surface. Leakage current of total BSTO films decreased with increasing amorphous layer thickness due to structural modifications. Dielectric constant showed maxi-mum value of 343 when amorphous layer thickness was 30 nm at which the improvement by grain growth and the degradation by amorphous phase were balanced.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.248.2-248.2
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• 2014

In this study, the optical properties and structural characteristics of gallium nitride (GaN) thin films prepared by radio frequency (RF) magnetron sputtering were investigated. Auger electron and X-ray photoelectron spectra showed that the deposited films consisted mainly of gallium and nitrogen. The presence of oxygen was also observed. The optical bandgap of the GaN films was measured to be approximately 3.31 eV. The value of the refractive index of the GaN films was found to be 2.36 at a wavelength of 633 nm. X-ray diffraction data revealed that the crystalline phase of the deposited GaN films changed from wurtzite to zinc-blende phase upon decreasing the sputtering gas pressure. Along with the phase change, a strong dependence of the microstructure of the GaN films on the sputtering gas pressure was also observed. The microstructure of the GaN films changed from a voided columnar structure having a rough surface to an extremely condensed structure with a very smooth surface morphology as the sputtering gas pressure was reduced. The relationship between the phase and microstructure changes in the GaN films will be discussed.

• Journal of the Korean Society for Heat Treatment
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• v.12 no.3
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• pp.199-205
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• 1999

The quaternary Ti-Al-V-N films have been grown on glass substrates by reactive dc and rf magnetron sputter deposition from a Ti-6Al-4V target in mixed Ar-$N_2$ discharges. The Ti-Al-V-N films were investigated by means of X-ray diffraction(XRD), electron probe microanalysis(EPMA) and scratch tester. Both XRD and EPMA results indicated that the Ti-Al-V-N films were of single B1 NaCl phase having columnar structure with the (111) preferred orientation. Scratch tester results showed that the adhesion strength of Ti-Al-V-N films which treated with substrate heating and vacuum annealing was superior to that of as-deposited film. The good adhesion strength was also achieved in the double-layer structure of Ti-Al-V-N/Ti-Al-V/Glass.

• Tribology and Lubricants
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• v.4 no.2
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• pp.36-43
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• 1988

Titanium carbide(TiC) and titanium nitride(TiN) flims were deposited on $Si_3N_4$-TiC composite cutting tools by chemical vapor deposition(CVD) using $TiCl_4-CH_4-H_2$ and $TiCl_4-H_2-N_2$ gas mixtures, respectively. The nonmetal to metal ratio of deposit increases with increasing $m_{C/Ti}$(mole ratio of CH$_4$ to TiCl$_4$ in the input) for TiC coatings and $m_{N/Ti}$(mole ratio of N$_2$ to TiCl$_4$ in the input) for TiN coatings. The nearly stoiahiometric films could be obtained under the deposition condition of $m_{C/Ti}$ between 1.15 and 1.61 for TiC, and that of $m_{N/Ti}$ between 25 and 28 for TiN. Also maximum microhardness of the coatings can be obtained in these ranges. The interfacial region of TiC coatings on $Si_3N_4$-TiC ceramics is wider than that of TiN coatings according to Auger depth profile analysis, which indicates good interfacial bonding for TiC. Experimental results show that TiC coatings have an randomly equiaxed structure and Columnar structure with(220) preferred orientation can be obtained for TiN coatings. And, multilayer coatings have a dense and equiaxed structure.

• Journal of The Geomorphological Association of Korea
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• v.24 no.3
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• pp.47-59
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• 2017

This study aims to analyze geomorphologically Jaein Falls in Hantangang Lava Plateau for the landform structure, landform classification, falls dissection and recession. The height and recession length of the Falls are approximately 18m and 340m. after dissection valley arrive at area of the Jijangbong Volcanic Rock Complex of Mesozoic era, the fall will disappear. The structure of the dissection valley shows totally well vertical columnar joint near falls and plunge pool, colluvial talus deposits toward lower reach by the freezing-thawing and wet-dry activities, and alluvial cone and delta in estuary to Hantangang River. The Falls' age date and recession rate in the valley maybe relate to the age of the lava plateau. The estimated recession rate of the fall should be 8.75m/ka to 2.3m/ka, depending on the age 500ka to 40ka in lava plateau.

• Korean Journal of Materials Research
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• v.26 no.4
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• pp.207-211
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• 2016

Ti films were deposited on glass substrates under various preparation conditions in a chamber of two-facing-target type dc sputtering; after deposition, the electric resistivity values were measured using a conventional four-probe method. Crystallographic orientations and microstructures, including the texture and columnar structure, were also investigated for the Ti films. The morphological features, including the columnar structures and surface roughness, are well explained on the basis of Thornton's zone model. The electric resistivity and the thermal coefficient of the resistivity vary with the sputtering gas pressure. The minimum value of resistivity was around 0.4 Pa for both the $0.5{\mu}m$ and $3.0{\mu}m$ thick films; the apparent tendencies are almost the same for the two films, with a small difference in resistivity because of the different film thicknesses. The films deposited at high gas pressures show higher resistivities. The maximum of TCR is also around 0.4 Pa, which is the same as that obtained from the relationship between the resistivity and the gas pressure. The lattice spacing also decreases with increasing sputtering gas pressure for both the $0.5{\mu}m$ and $3.0{\mu}m$ thick films. Because they are strongly related to the sputtering gas pressures for Ti films that have a crystallographic anisotropy that is different from cubic symmetry, these changes are well explained on the basis of the film microstructures. It is shown that resistivity measurement can serve as a promising monitor for microstructures in sputtered Ti films.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.707-714
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• 1999

To save electrical energy as much as 40 % for fluorescent lighting, the reflectors coated with silver reflective thin films recently became popular with higher reflectivities and long life. The thin films fabricated by using sputtering techniques are produced mainly in U.S.A. On the other hand, some silver films deposited by using evaporation methods show low adhesion in general, although the reflectivity is no problem. We have studied various PVD methods to obtain thin films with high reflectivity and adhesion on a substrate of polyester, for a couple of years. Silver films manufactured byusing evaporation showed the reflectivity of 96.4 % and the adhesion of $12 kg/\textrm{cm}^2$. while samples manufactured by using sputtering depicted the adhesion as much as $20 Kg/\textrm{cm}^2$ that is almost double, although their reflectivity was not much different. X-ray diffraction spectra for the sputtered films demonstrated a preferential growth on (111) plane and the cross-sections of the specimens revealed a dense columnar structure to result in the enhanced adhesion.

• Applied Microscopy
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• v.41 no.4
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• pp.257-263
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• 2011

The microanatomy and ultrastructure of the digestive diverticulum of Mytilus galloprovincialis were described using light and electron microscopy. The digestive diverticulum of tawny color was surrounded the stomach and connected to stomach by a primary duct. Digestive diverticulum is composed of numerous digestive tubules. The epithelial layer of a simple digestive tubule, which is simple, is composed of basophilic cells and digestive cells. Basophilic cells are columnar in shape, and has a well-developed endoplasmic reticula, tubular mitochondria, Golgi complex and membrane-bounded granules of high electron density in the cytoplasm. Whereas digestive cells are columnar in shape, with development of microvilli and cilia on the free surface. Pinocytic vasicles, active lysosomes and numerous mitochondria were observed in the apical cytoplasm of digestive cells. The results of this study suggest that basophilic cell and digestive cell of the digestive tubule are specialized in the extracellular and intracellular digestion, respectively.

• Applied Microscopy
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• v.26 no.1
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• pp.17-31
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• 1996

The venomous apparatus of the black widow spider, Latrodectus mactans, is composed of chelicera and paired venom glands in the cephalothorax. Each glands is surrounded by a thin adventitia and striated muscular bundles resting on a basal membrane. Along the musculature neuromuscular synaptic contacts are formed by a motor axon and the muscle fibers. The secretory epithelium, which made up of simple and long columnar cells with extensive finger-like processes, creates a simple acinar gland. The secretory surfac is increased by a sort of fringes extended from the basal membrane into the gland lumen, and the luminal surface of the epithelium is marked by the presence of closely spaced microvilli. The venoms of the black widow spider are produced from two types of secretory granules within the epithelial cells. During the secretory phase, these granules are transformed into droplets and suffering a condensation. Finally the secretory products are released by the apocrine secretion. After the gland is emptied, the basal epithelial cells present a high proliferative process and regenerate the columnar epithlial cells.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.12-21
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• 2022

Directed energy deposition (DED) was adopted as a metal additive manufacturing method to develop a mold for the hot stamping process. The test piece was machined from Heatvar laminate material, and results were obtained through microstructure and defect observations, as well as hardness, tensile strength, and joint strength tests. 1) Spherical pores and irregular-shaped cavities were observed as lamination defects, and columnar dendrites formed in the structure, which tended to become coarse upon heat treatment. 2) The hardness of the heat-treated material (480HV) was slightly lower than that of the non-heat-treated material (500HV). 3) In the tensile test, the maximum tensile stress and strain of the heat-treated material were 1392 MPa and 15%, respectively, which were slightly higher than the values of 1381 MPa and 13%, respectively, for the non-heat-treated material. 4) In the case of the early final fracture in the tensile test, in most cases, pores or irregularly shaped cavities were observed at the fracture surface or near the surface. 5) In the joint strength test, most of the specimens finally fractured in the laminated metal area, and the fracture surface was intragranular. In addition, dimples formed over the entire area on the fracture surface of the fractured specimen after sufficient elongation.