• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.540-545
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• 2010

In this study, we have investigated new plasma resistant materials with less usage of rare-earth oxides than $Y_2O_3$ which is currently used in the semiconductor industry. We observed the stability ranges of $(Gd{\cdot}Y)_3Al_5O_{12}$ and $(La{\cdot}Y)Al_{11}O_{18}$ ternary systems, and measured their etch rates under typical fluorine plasma. $(Gd{\cdot}Y)_3Al_5O_{12}$ system showed an extensive solid solution up to 80 mol% gadolinium, but $(La{\cdot}Y)Al_{11}O_{18}$ showed a negligible substitution between rare-earth ions, which can be explained by the differences between the ionic radii. The etch rates depended on the total amount of rare-earth oxides but not on the substitution of the rare-earth ions. When the specimen was examined using XPS after the exposure to fluorine plasma, the strong surface fluorination was observed with a shift of the binding energy to higher energy.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.28-33
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• 2020

Plasma etching process employs high density plasma to create surface chemistry and physical reactions, by which to remove material. Plasma chamber includes silicon-based materials such as a focus ring and gas distribution plate. Focus ring needs to be replaced after a short period. For this reason, there is a need to find materials resistant to erosion by plasma. The developed chemical vapor deposition processing to produce silicon carbide parts with high purity has also supported its widespread use in the plasma etch process. Silicon carbide maintains mechanical strength at high temperature, it have been use to chamber parts for plasma. Recently, besides the structural aspects of silicon carbide, its electrical conductivity and possibly its enhanced life time under high density plasma with less generation of contamination particles are drawing attention for use in applications such as upper electrode or focus rings, which have been made of silicon for a long time. However, especially for high purity silicon carbide focus ring, which has usually been made by the chemical vapor deposition method, there has been no study about quality improvement. The goal of this study is to reduce surface roughness and depth of damage by diamond tool grit size and tool dressing of diamond tools for precise dimensional assurance of focus rings.

• Composites Research
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• v.20 no.4
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• pp.18-24
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• 2007

The mechanical and thermal properties of PAN-based/rayon-based carbon fabrics interply hybrid composite materials have been studied. Mechanical properties including tensile and interlaminar shear strengths were improved with increasing amount of continuous PAN-based carbon fabrics. The erosion rate and insulation index were determined through the torch test. Continuous rayon-based carbon fabrics composite indicated relatively low ablation resistant property. The thermal conductivity of hybrid composite of spun PAN-based/continuous rayon-based carbon fabrics is lower than that of the continuous PAN-based carbon fabrics composite.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.211-211
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• 1999

Titanium nitride (TiN) thin films have useful properties including high hardness, good electrical conductivity, high melting point, and chemical inertness. The applications have included wear-resistant hard coatings on machine tools and bearings, decorative coating making use of the golden color, thermal control coatings for widows, and erosion resistant coatings for spacecraft plasma probes. For all these applications as feature sizes shrink and aspect ratios grow, the issue of good step coverage becomes increasingly important. It is therefore essential to manufacture conformal coatings of TiN. The growth of TiN thin films by chemical vapor deposition (CVD) is of great interest for achieving conformal deposition. The most widely used precursor for TiN is TiCl4 and NH3. However, chlorine impurity in the as-grown films and relatively high deposition temperature (>$600^{\circ}C$) are considered major drawbacks from actual device fabrication. To overcome these problems, recently, MOCVD processes including plasma assisted have been suggested. In this study, therefore, we have doposited Ti(C, N) thin films on Si(100) and D2 steel substrates in the temperature range of 150-30$0^{\circ}C$ using tetrakis diethylamido titanium (TDEAT) and titanium isopropoxide (TIP) by pulsed DC plamsa enhanced metal-organic chemical vapor deposition (PEMOCVD) method. Polycrystalline Ti(C, N) thin films were successfully grown on either D2 steel or Si(100) surfaces at temperature as low as 15$0^{\circ}C$. Compositions of the as-grown films were determined with XPS and RBS. From XPS analysis, thin films of Ti(C, N) with low oxygen concentration were obtained. RBS data were also confirmed the changes of stoichiometry and microhardness of our films. Radical formation and ionization behaviors in plasma are analyzed by optical emission spectroscopy (OES) at various pulsed bias and gases conditions. H2 and He+H2 gases are used as carrier gases to compare plasma parameter and the effect of N2 and NH3 gases as reactive gas is also evaluated in reduction of C content of the films. In this study, we fond that He and H2 mixture gas is very effective in enhancing ionization of radicals, especially N resulting is high hardness. The higher hardness of film is obtained to be ca. 1700 HK 0.01 but it depends on gas species and bias voltage. The proper process is evident for H and N2 gas atmosphere and bias voltage of 600V. However, NH3 gas highly reduces formation of CN radical, thereby decreasing C content of Ti(C, N) thin films in a great deal. Compared to PVD TiN films, the Ti(C, N) film grown by PEMOCVD has very good conformability; the step coverage exceeds 85% with an aspect ratio of more than 3.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.37-52
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• 2017

Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

• Journal of Pharmaceutical Investigation
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• v.32 no.3
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• pp.165-172
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• 2002

Injectable gel composed of egg phosphatidylcholine (egg PC), hyaluronate (HA) and water was formulated for local drug delivery. The lamellar liquid crystalline structure of the egg PC/water system did not change by adding HA in the formulation. However, egg PC/HA/water gel was more resistant to erosion than the egg PC/water gel. The egg PC/HA/water and egg PC/water gels containing model drugs, tetracycline and sudan IV were prepared to perform in vitro and in vivo drug release experiments. In vitro release of tetracycline was sustained in the gel type formulations. The release rate of hydrophobic sudan IV was extremely slow. More than 99% of sudan IV remained inside the gel after 5 days. In vivo release of drugs from the air pouch model in Balb/c mice shows that lipophilic sudan IV remained for more than 10 days whereas tetracycline remained for 1 day in the pouch. The compatibility of the gels was also examined by histopathology. The gels did not cause any adverse inflammatory effect in the air pouch.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.514-527
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• 2004

We investigated the distribution and geomorphic development of alluvial fans at Cheongdo- and Hweyang-eup(town) in the Cheongdo Basin, Gyeongsangbuk-do(Province) of Korea. The alluvial fans of study area are formed confluently to the E-W direction at the northern slope of the Mt. Namsan(840 m). They are classified into Higher surface, Middle surface, and Lower surface according to a relative height to a river bed. And the older alluvial fan is, the deeper gravel in the stream deposits is weathered. The magnitude of each surface composing of confluent fans is related to that of the drainage basin. So called fan-basin system of magnitude on the study area is on the positive(+) relation in the study area. The large fans over 1km in radius are found on the basin of andesite rock which is resistant to the weathering and erosion. Moreover there is no tectonic movement in the basin. It means the most important element influenced on the fan formation is not tectonic movement, but the Quaternary climatic change, which is the periglacial climate alternating glacial and interglacial stages during the Quaternary. Therefore alluvial fans would distribute in Korea overall influenced by the Quaternary climatic change.

• Journal of the Korean GEO-environmental Society
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• v.15 no.10
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• pp.53-62
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• 2014

In Korea, the pipe type that has been well used as sewage pipe from the past is primarily a rigid pipe which is represented by concrete hume pipe, but the use of it is being decreased sharply because of the problems such as tube erosion and incomplete watertightness securing through the time. On the other hand, the use of flexible pipe has been increased because its construction ability is excellent on account of its light weight as well as it is resistant to corrosion. However, because there are lacks of market's confidence in flexible pipe and occurrence cases of partial damage incomplete caused by compaction control, cause analysis and management for them are needed. Therefore, this study tried to estimate the deformation characteristics of pipe caused by each condition through numerical analysis changing construction sequence, rigidity of pipe, strength of ground concrete under the pipe, relative compaction ratio of sand foundation under the pipe and relative compaction ratio of backfill material above the pipe. Evaluation result is that influence on each factor is confirmed and the quality control of sand around the pipe are turned up to be important.

• Journal of Acupuncture Research
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• v.32 no.3
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• pp.27-40
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• 2015

Objectives : This study was performed to evaluate the effects of water extract of Cervi Parvum Cornu(CPC), Aconiti Lateralis Radix Preparata(ALR), and Yongbu-tang(YBT) on suppression of the receptor activator of nuclear factor kappa-B ligand(RANKL)-induced osteoclast differentiation and bone resorption. Methods : The effects of CPC, ALR, YBT extracts on osteoclast differentiation were determined by culture of bone marrow macrophage(BMM). The mRNA expression levels of the nuclear factor of activated T-cells cytoplasmic 1(NFATc1), c-Fos and tartrate-resistant acid phosphatase(TRAP) in BMMs were analyzed by reverse transcriptase polymerase chain reaction(RT-PCR). Similarly, the protein expression levels of NFATc1, c-Fos, mitogen-activated protein kinase(MAPK)s and ${\beta}$-actin in cell lysates were measured by western blotting. In addition, effects of CPC, ALR and YBT extracts were determined by means of Lipopolysaccharide(LPS)-induced bone-loss with mice. Results : CPC, ALR and YBT extracts showed remarkable inhibition on RANKL-induced osteoclast differentiation without cytotoxicity. CPC and ALR extracts significantly reduced the protein expression level of NFATc1. YBT extract significantly reduced the mRNA expression levels of c-Fos, NFATc1 and the protein expression levels of c-Fos, NFATc1, AKT, p38, c-Jun N-terminal kinase(JNK). Further, YBT extract suppressed degradation of$ I-{\kappa}B$. And ALR extract significantly restored the bone erosion by LPS treatment in mice. Conclusions : YBT extract showed more remarkable inhibition on osteoclast differentiation than CPC and ALR extracts in vitro. ALR extract showed remarkable inhibition on bone resorption in vivo. Thus, YBT extract can be a useful treatment for bone-loss diseases such as osteoporosis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.369-373
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• 1985

The characteristics of a pathogen isolated from infected tilapia, which showed the external symptoms of fin erosion and body deceleration, were examined. The strain of isolated pathogen was identified as Flexibactor columnaris, The normal tilapia dipped into suspensions of the isolated pathogens has developed the infective symptoms. The strain of Flexibactor columnaris was sensitive to kanamycin, tetracycline, and amikacine, but resistant against sulfa drugs. This strain could not grow in the cytophaga media containing over $2\%$ NaCl or over $50\%$ sea water. In cytophaga broth containing more than $50\%$ or sea water instead of distilled water, the number of Flexibacter columnaris decreased from about $10^6/ml\;to\;10^4ml$ within one hour after inoculation. On the other hand, in cytorhaga broth containing more than $5\%$ of NaCl, the number rapidely reached less than 10/ml from about $10^5/ml$ within one hour after inoculation.