• 한국세라믹학회지
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• 제47권6호
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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.

• 반도체디스플레이기술학회지
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• 제19권4호
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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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• 제20권4호
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• pp.18-24
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• 2007

본 연구에서는 전구체의 종류에 따라 PAN계/rayon계, 직물의 형태에 따라 연속사 및 방적사 탄소 직물을 사용하여 하이브리드 복합재료를 제조하여 역학적 특성과 열적 특성을 살펴보았다. 인장, 층간 전단강도 실험을 통해 연속사 PAN계 탄소 직물을 많이 사용한 하이브리드 복합재료에서 우수한 역학적 특성을 보이는 것으로 확인되었다. 토치 테스트에서는 rayon계 탄소 직물 복합재료의 삭마 저항성이 가장 떨어짐을 확인할 수 있었다. 또한, 방적사 PAN계 탄소 직물과 rayon계 탄소 직물을 하이브리드화한 복합재료가 면내 방향과 수직 방향 모두에서 저 열전도도 구현에 유리한 특성을 보여주었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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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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• 제4권1호
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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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• 제32권3호
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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.

• 대한지리학회지
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• 제39권4호
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• pp.514-527
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• 2004

경북 청도분지의 청도읍과 화양읍을 중심으로 선상지 분포와 지형발달을 조사하였다. 청도분지 남동쪽에 남산(840m)을 최고봉으로 하는 산지 전면에 동-서 방향으로 연속되어 나타나는 합류선상지는 하상비고가 다른 고위면, 중위면, 저위면의 세 지형면으로 구분된다. 선상지를 이루는 역층은 하천에 의해 운반, 퇴적되었으며, 오래된 것일수록 자갈의 풍화 정도가 심하였다. 합류선상지를 구성하는 각 선상지 지형면의 크기와 지형면을 형성하는 하천 유역분지 크기와의 관계, 즉. 규모에 있어서 선상지-유역분지 체계는 정의 상관관계에 있다. 청도분지에는 단층선이 통과하지 않을 뿐 아니라 선상지를 형성한 하천 유역분지의 기반암이 풍화와 침식에 대한 저항력이 강한 안산암이지만. 반경 1 km 이상인 선상지가 분포한다. 이러한 현상으로 볼 때, 우리나라에서 선상지 형성에 가장 크게 영향을 미치는 요소는 빙기와 간빙기가 반복된 제4기 기후변화이다. 따라서 제4기 동안 거의 같은 정도로 기후변화의 영향을 받은 한반도에서 선상지는 단층선의 유무와 관계없이 보편적으로 형성될 수 있는 지형이다.

• 한국지반환경공학회 논문집
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• 제15권10호
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• pp.53-62
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• 2014

국내의 경우 하수관으로 많이 사용되어 온 관종은 콘크리트 흄관으로 대표되는 강성관이 주를 이루고 있으나, 시간 경과에 따른 관 부식 및 수밀성 부족 등의 이유로 사용이 급격히 감소하고 있다. 반면에 연성관은 부식에 강할 뿐만 아니라 자재의 무게가 경량이어서 시공성이 우수한 장점이 있어 사용이 증가하고 있는 실정이다. 그러나 연성관에 대한 시장의 신뢰성 부족과 미흡한 다짐관리로 인한 국부적인 파손사례가 발생하고 있어 이에 대한 원인분석 및 관리방안이 필요한 실정이다. 이에 본 연구에서는 시공순서, 관의 강성, 관 하부 콘크리트 기초의 강도, 관 하부 모래기초의 다짐도, 관 주변 모래의 다짐도 및 관 상단 되메움재의 다짐도 등을 변화시켜 가며 각각의 조건에 따른 관의 변형특성을 수치해석을 통하여 평가하였다. 평가결과 각 인자에 대한 영향을 확인할 수 있었으며 특히 연성관의 경우 관 주변 모래의 품질관리가 중요한 것으로 나타났다.

• Journal of Acupuncture Research
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• 제32권3호
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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.

• 한국수산과학회지
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• 제18권4호
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• pp.369-373
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• 1985

지느러미 부식과 체색변화를 나타내는 틸라피아 병어로부터 분리한 병원균의 성상은 다음과 같다. 1. 병어로부터 분리한 병원균은 Flexibacter clumnaris로 동정되었다. 2. 분리한 병원균액으로 인위감염시켰을 때 전형적인 columnaris병 증상을 나타냈다. 3. 병원균은 kanamycin, tetracycline, amikacin 등에서 높은 감수성을 나타냈으나, sulfa제에서는 거의 감수성을 나타내지 않았다. 4. $2\%$ 이상 식염이나 $50\%$이상 해수를 함유한 cytophaga배지에서 병원균은 자라지 못했다. 5. 증류수 대신 $50\%$ 이상 해수를 함유한 Cytophaga배지에 병원균을 접종시킨 후 1시간만에 약 11에서 $10^6/ml$에서 $10^4ml$로 균수가 감소했는 데 반하여, $5\%$ 이상 식염을 함유한 cytophaga 배지에서는 접종 후 1시간만에 균수가 약 $10^5/ml$에서 10/ml 이하로 급격히 감소했다.