• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1038-1041
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• 2003

In the paper, we investigated silicon surface microstructures formed by reactive ion etching in hollow cathode system. Wet anisotropic chemical etching technique use to form random pyramidal structure on <100> silicon wafers usually is not effective in texturing of low-cost multicrystalline silicon wafers because of random orientation nature, but High density hollow cathode plasma system illustrates high deposition rate, better film crystal structure, improved etching characteristics. The etched silicon surface is covered by columnar microstructures with diameters form 50 to 100nm and depth of about 500nm. We used $SF_{6}$ and $O_{2}$ gases in HCP dry etch process. This paper demonstrates very high plasma density of $2{\times}10^{12}$ $cm^{-3}$ at a discharge current of 20 mA. Silicon etch rate of 1.3 ${\mu}s/min$. was achieved with $SF_{6}/O_{2}$ plasma conditions of total gas pressure=50 mTorr, gas flow rate=40 sccm, and rf power=200 W. Our experimental results can be used in various display systems such as thin film growth and etching for TFT-LCDs, emitter tip formations for FEDs, and bright plasma discharge for PDP applications. In this paper we directed our study to the silicon etching properties such as high etching rate, large area uniformity, low power with the high density plasma.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.9
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• pp.717-722
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• 2012

In this work, we study on the effects of the oxygen pressure on the structural and crystalline of MgZnO thin films. MgZnO thin films were deposited on p-Si (111) substrates by using pulsed laser deposition. The X-ray diffraction analysis and energy-dispersive X-ray results revealed that as the oxygen pressure increased and Mg content in the MgZnO films decreased. Also Crystal structure was changed from cubic rock salt to hexagonal wurtzite. Alpha step and atomic force microscopy results showed that the thickness of the films are about 100 nm, and it has been found that the MgZnO (002) preferred orientation were deposited with increasing the oxygen pressure. Therefore, the effect of the preferred orientation, the crystallization grew in the form of the columnar; Grain size and RMS of the films were increased with increasing oxygen pressure.

• The Korean Journal of Malacology
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• v.4 no.1
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• pp.1-16
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• 1988

The authors observed histochemical and ultrastructural characters on the osphradium of Rapana venosa Valenciennes using light microscope, scanning and transmission electron microscpes. The results were as follows:1)The basic structure of osphradium was bipectinated shape, which consisted of a septum situating in the center of osphradium and numerous osphradial leaflets. On the other hand, Epidermis of ospradial leaflets formed the structure of pseudostratified ciliated columnar epithelium which was composed of an epithelial cell layer, a basal cel layer and a neuropile. 2) Ciliated dpithelial cells:A large number of these cells were observed on the lateral and ventral regions but a small number of them were observed on the dorsal region. These cells had cylindrical microvilli, slender mitochondria and serve fibers.3) Supporting cells: These cells had cylindrical microvilli, spongy layer, electron dense granules, mitochondria and nerve fibers4) Four types secretory epothelial cells: Four distinct types of secretory epithelial cells were recognized and were arbitrily designated as Type I, Type II, Type III and Type IV.cell type I: These cells contained electron denwe granules(diameter, 0.94-1.56${\mu}{\textrm}{m}$), well developed Golgi apparatus and rough endoplasmic reticula, cell type II: These cills contained two types of granules of the different electron density. One was high electron density granules which were 0.4-1.0${\mu}{\textrm}{m}$ in diameter, The other was low electron density granules which were 0.75-1.2${\mu}{\textrm}{m}$ in diameter.cell type III:These cells had fibrous secretory materials and exhibited strongly positive reaction with Toluidine blue.cell type IV:A large number of this type of cells were observed on the ventral region of ospgradial leaflets and positively reacted with periodic acid Schiff reagent. 5)Dark cells contained several electron dense cillaty rootlets and unmerous granules but cellular organelles were not observed.6) Four types basal cells: Four distinci types of basal cells were recognized and arbitrarily designated as Type I, Type II, Type III and Type IV.Cell type I(light cell): These cells exhibited low electuon density and contained short smooth endoplasmic reticula, several vacuoles and granules.

• Journal of The Geomorphological Association of Korea
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• v.24 no.3
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• pp.27-45
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• 2017

At the upper part of terrace deposits at Jeongdongjin area, there is a structure in which reddish brown and grayish white layers laying horizontally. Previous studies have reported the existence of these structures within the deposits and suggested the theoretical background related to the formation process. However, the analysis of physical properties and chemical composition such as particle size, classification, etc. of the materials constituting the reddish brown and grayish white layers is scarcely done. In this study, the physico - chemical properties of gray - white and reddish brown beds are investigated. The mean grain size of the particles was less than $4{\varphi}$ in both layers and the reddish brown layer was more coarse. The results shows that the sorting of the grayish white layer is better. The chemical composition of both layers shows that the average concentration of $SiO_2$, $Al_2O_3$ and $K_2O$ of the grayish white layer was higher than those of the reddish brown layer. The concentration of $Fe_2O_3$ of reddish brown lyaer was 3 times higher than those of the grayish white layer. The degree of chemical weathering (CIA) is 90 or so in both the reddish brown and grayish white layers, indicating a significant level of chemical weathering. In conclusion, reddish brown layers had been formed by the processes related to the migration of iron and the migration of water that induced aggregation after the formation of sediments (psudo-gleization). In this study area, a vertical layer of grayish white which cuts off horizontal reddish brown and grayish white color was found. The vertical layer or wedge similar to a ice-wedge or columnar structure that in a cold environment, and there is a difference in shape and size. The vertical layer appears to have occurred three or more cycles. The vertical layers begin to form at a certain height within the outcrop and descend downwards, which of course is difficult to see as directing certain times.

• Applied Microscopy
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• v.33 no.3
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• pp.223-231
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• 2003

Histology and ultrastructure of the gill in the granular ark, Tegillarca granosa are described using light and transmission electron microscopy. The gill of the clam have typical structure of the filibranch type. The gill filament have several band of lateral and apical cilia. The epithelial layer surrounding the hemolymph sinus is simple and consists of epithelial cells, ciliated cells and secretory cells. The epithelial cells are usually squamous and covered with microvilli. The ciliated cells are usually columnar and can be divided into two types (A and B). Type A cells are more abundance and have lower electron density than B cells. Ultrastructure of the cilia showed that '9+2' microtubular structure of the axial filament and '$2{\times}9$' proximal centriole structure in the cross section. Secretory cells are mainly observed in the apical region of the filament and can be divided into three types of A, B and C with morphological features of the secretory granules. Type A cells of oval shaped are more abundance than other secretory cells and contains numerous secretory granules of low electron dense. Type B cells contains secretory granules of membrane-bounded and high electron dense. Secretory granules of type C cells are elliptical and fine granules surrounding the homogeneous core materials.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.25-31
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• 2008

Cp-Ti and Ti-6Al-4V alloys commonly used dental implant materials, particularly for orthopaedic and osteosynthesis because of its suitable mechanical properties and excellent biocompatibility. This alloys have excellent corrosion behavior in the clinical environment. The first factor to decide the success of dental implantation is sufficient osseointegration and high corrosion resistance between on implant fixture and its surrounding bone tissue. In this study, in order to increase corrosion resistance and biocompatibility of Cp-Ti and Ti-6Al-4V alloy that surface of manufactured alloy was coated with TiN by RF-magnetron sputtering method. The electrochemical behavior of TiN coated Cp-Ti and Ti-6Al-4V alloy were investigated using potentiodynamic (EG&G Co, PARSTAT 2273. USA) and potentiostatic test (250mV) in 0.9% NaCl solution at 36.5 $\pm$ 1$^{\circ}C$. These results are as follows : 1. From the microstructure analysis, Cp-Ti showed the acicular structure of $\alpha$-phase and Ti-6Al-4V showed the micro-acicular structure of ${\alpha}+{\beta}$ phase. 2. From the potentiodynamic test, Ecorr value of Cp-Ti and Ti-6Al-4V alloys showed -702.48mV and -319.87mV, respectively. Ti-6Al-4V alloy value was higher than Cp-Ti alloy. 3. From the analysis of TiN and coated layer, TIN coated surface showed columnar structure with 800 nm thickness. 4. The corrosion resistance of TiN coated Cp-Ti and Ti-6Al-4V alloys were higher than those of the non-coated Ti alloys in 0.9% NaCl solution from potentiodynamic test, indicating better protective effect. 5. The passivation current density of TiN coated Cp-Ti and Ti-6Al-4V alloys were smaller than that of the noncoated implant fixture in 0.9% NaCl solution, indicating the good protective effect resulting from more compact and homogeneous layer formation.

• Korean Journal of Materials Research
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• v.22 no.2
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• pp.97-102
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• 2012

The microstructure and tensile properties of Al-Mn/Al-Si hybrid aluminum alloys prepared by electromagnetic duocasting were investigated. Only the Al-Mn alloy showed the typical cast microstructure of columnar and equiaxed crystals. The primary dendrites and eutectic structure were clearly observed in the Al-Si alloy. There existed a macro-interface of Al-Mn/Al-Si alloys in the hybrid aluminum alloys. The macro-interface was well bonded, and the growth of primary dendrites in Al-Si alloy occurred from the macro-interface. The Al-Mn/Al-Si hybrid aluminum alloys with a well-bonded macro-interface showed excellent tensile strength and 0.2% proof stress, both of which are comparable to those values for binary Al-Mn alloy, indicating that the strength is preferentially dominated by the deformation of the Al-Mn alloy side. However, the degree of elongation was between that of binary Al-Mn and Al-Si alloys. The Al-Mn/Al-Si hybrid aluminum alloys were fractured on the Al-Mn alloy side. This was considered to have resulted from the limited deformation in the Al-Mn alloy side, which led to relatively low elongation compared to the binary Al-Mn alloy.

• Journal of the Korean institute of surface engineering
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• v.38 no.1
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• pp.21-27
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• 2005

Tensile properties and hardness of nickel electroform from chloride-free nickel sulfamate electrolyte at 50℃ and PH 4.5 were investigated. Current density varied from 20 to 60 mA/㎠. The deposit thicknesses were 360, 480 and 980 ㎛. It was found in 480 ㎛ thick electroform that highest tensile and yield strengths and hardness of 83.7 ksi, 53.6 ksi and 216 DPH, respectively were obtained at a current density of 40 mA/㎠ and they were slightly decreased at 20 and 60 mA/㎠. However the ductility was lowest of 7.9% at 40 mA/㎠. Such a high strength and low ductility at 40 mA/㎠ seems to be related to the narrower columnar structure than those of other current densities. All the deposits exhibited pronounced necking behavior. Tensile strength, yield strength and ductility increased as the nickel electroform thickens. Initial strong (200) texture developed on stainless steel mandrel decreased and (111) and (220) textures increased as deposit thickness increased, whereas (200) texture was preferred as the current density increased.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.85-91
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• 2006

Electron Beam Physical Vapor Deposition (EB-PVD) was applied to fabricate a thin film YSZ electrolyte with large area on the porous NiO-YSZ anode substrate. Microstructural and thermal stability of the as-deposited electrolyte film was investigated via SEM and XRD analysis. In order to obtain an optimized YSZ film with high stability, both temperature and surface roughness of substrate were varied. A structurally homogeneous YSZ film with large area of $12\times12\;cm^2$ and high thermal stability up to $900^{\circ}C$ was fabricated at the substrate temperature of $T_s/T_m$ higher than 0.4. The smoother surface was proved to give the better film quality. Precise control of heating and cooling rate of the anode substrate was necessary to obtain a very dense YSZ electrolyte with high thermal stability, which affords to survive after post heat treatment for fabrication a cathode layer on it as well as after long time operation of solid oxide fuel cell at high temperature.

• Journal of Sensor Science and Technology
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• v.15 no.3
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• pp.216-221
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• 2006

ZnO thin films prepared by PLD method exhibit an excellent optical property, but may have some problems such as incomplete surface roughness and crystallinity. In this study, undoped ZnO buffer layers were deposited on (0001) sapphire substrates by ultra high vacuum pulse laser deposition (UHV-PLD) and molecular beam epitaxy (MBE) methods, respectively. After post annealing of ZnO buffer layer, undoped ZnO thin films were deposited under different oxygen pressure ($35{\sim}350$ mtorr) conditions. The Arsenic-doped (1, 3 wt%) ZnO thin layers were deposited on the buffer layer of undoped ZnO by UHV-PLD method. The optical property of the ZnO thin films was analyzed by photoluminescence (PL) measurement. The ${\theta}-2{\theta}$ XRD analysis exhibited a strong (002)-peak, which indicates c-axis preferred orientation. Field emission-scanning electron microscope (FE-SEM) revealed that microstructures of the ZnO thin films were varied by oxygen partial pressure, Arsenic doping concentration, and deposition method of the undoped ZnO buffer layer. The denser and smoother films were obtained when employing MBE-buffer layer under lower oxygen partial pressure. It was also found that higher Arsenic concentration gave the enhanced growing of columnar structure of the ZnO thin films.