• Title/Summary/Keyword: surface alteration

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NEW METHODS OF THE GROWING COMPLICATED SHAPED SAPPHIRE PRODUCTS: VARIABLE SHAPING TECHNIQUE AND LOCAL DYNAMIC SHAPING TECHNIQUE

  • Borodin, V.A.;Sidorov, V.V.;Steriopolo, T.A.
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 1999.06a
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    • pp.209-225
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    • 1999
  • Detailed description of the crystal growth methods permitting one to obtain complicated shape crystals from the melt is given. The variable shaping technique provides the growth of crystals with a discrete altering cross-section configuration during crystallization. The dynamic local shaping technique enables one to grow items with a continuous alteration of the side surface profile by a preset program.

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The Study on the Phase Transition of Langmuir Film by Brewster-Angle Microscope (BAM(Brewster-Angle Microscope)으로 관측한 Langmuir막의 상전이에 관한 연구)

  • Cho, Wan-Je;Song, Kyung-Ho;Park, Tae-Gone;Park, Keun-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05b
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    • pp.323-326
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    • 2000
  • In this study, we used Brewster-Angle Microscope(BAM) to study on the molecular orientation of monolayer on the water surface. The behaviors of molecules on three different subphase have been observed. Reproducible $\pi$-A isotherm have been obtained only on information about phase transition by molecular area. BAM facilitates the observation of morphology by optical anisotropy and thickness in monolayer and multilayers as BAM is shown to be sensitive to anisotropy of film. Every transition was found by BAM technique, either as a dramatic change in degree of contrast or as a sudden alteration of molecular action and $\pi$-A isotherm.

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Geophysical Exploration on Unconformity-type Uranium Deposit in Athabaska Basin, Canada (캐나다 아타바스카 분지 부정합형 우라늄광상 물리탐사 사례)

  • You, Young-June;Kim, Jae-Chul
    • 한국지구물리탐사학회:학술대회논문집
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    • 2009.05a
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    • pp.73-87
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    • 2009
  • Geophysical survey for unconformity-type uranium deposit applied to this study area in Athabaska Basin, Canada were carried out airborne TEM and magnetic, resistivity-induced polarization (DC-IP), puser seismic reflection and well-logging method. The results of airborne survey interpreted the lithological boundary, geological structures, and conductors. Also, these results decided to main targets for ground DC-IP survey. The Low resistivity and the high chargeability slices of 3D modeling interpreted from DC-IP survey response for conductors related to hydrothermal alteration zones and fault-controlled graphitic zones occurring at the unconformity-type uranium deposit, and they confirmed by diamond drilling. Seismic results interpreted to lake bottom surface, alluvium layer and intra-sandstone faults. We suggest the resonable field data acquisition of DC-IP method on the land or the lake in Athabaska Basin.

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New methods of the growing complicated shaped sapphire products: variable shaping technique and local dynamic shaping technique

  • Borodin, V.A.;Sidorov, V.V.;Steriopolo, T.A.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.4
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    • pp.417-423
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    • 1999
  • Detailed description of the crystal growth methods permitting one to obtain complicated shape crystals from the melt is given. The variable shaping technique provides the growth of crystals with a discrete altering cross-section configuration during crystallization. The dynamic local shaping technique enables one to grow items with a continuous alteration of the side surface profile by a preset program.

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Runoff Characteristics Analysis for Interior Drainage Systems in Urban Basin -Application of SWMM- (도시유역의 내수배제시스템 설계를 위한 유출특성분석 -SWMM의 적용-)

  • Choi, Yun-Young;Lee, Yeong-Hwa
    • Journal of Environmental Science International
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    • v.9 no.3
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    • pp.193-199
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    • 2000
  • This study is carried out the analysis of the runoff characteristics for the design of the interior drainage systems by SWMM in urbanization basin. The basin analyzed in this study is Bumuh-chun basin which is located in Susung-gu of Taegu city. Huff method is used for rainfall distribution analysis. The optimal rainfall duration in Bumuh-chun basin is analyzed as about 90 minutes decided from comparison of arrival time and critical duration. Flood flow variation pattern is proposed through the comparison of the results of peak flow and peak time analyzed by SWMM about pre-urbanization and post-urbanization of Bumuh-chun basin. It is known that the variation of arrival time caused by the rapid increase of pavement rate in the upper area shows about 20∼25 minutes faster than pre- urbanization. Therefore, the management of surface water for design of water supply and drainage, and channel alteration has to considered the variation of geological factors according to urbanization.

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A Behavior of Rolling Contact Fatigue on Retained Austenite in High-Carbon Chromium Bearing Steel (고탄소 크롬 베어링 강에서의 잔류 오스테나이트 변화에 따른 회전접촉 피로거동)

  • Jin, Jai Koan;Kim, Dong Keon
    • Journal of the Korean Society for Heat Treatment
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    • v.7 no.3
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    • pp.190-198
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    • 1994
  • In order to study the effect of retained austenite on rolling contact fatigue in high-carbon chromium bearing steel, retained austenite was controlled by only tempering temperature, individually 200, 220 and $240^{\circ}C$. Among various microstructural alteration during rolling contact fatigue test, plate-like carbide most related to the flaking at sub-surface of contact pressure. The plate-like carbides formed during rolling contact fatigue test decrease with increasing tempering temperature, and fatigue life is much more improved. The retained austenite was decreased with the tempering temperature, and that decreased plate-like carbide formation. Therefore fatigue life is much more improved with decreasing retained austenite.

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Isolation and Identification of Cyanobacteria of the Cultural Heritages in the Gwanschoksa, Nonsan City in Korea (논산 관촉사 석조문화재에 분포하는 남세균의 분리 및 동정에 관한 연구)

  • Oh, In-Hye
    • The Journal of Natural Sciences
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    • v.19 no.1
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    • pp.27-35
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    • 2008
  • The importance of microbial activity in the alteration and deterioration of stone and concrete walls has been frequently neglected. Organisms present on stone monuments can include photolithoautotrophs, such as algae, cyanobacteria, mosses, and higher plants. Because of their ability to survive repeated drying and rehydration cycles and high UV levels, the cyanobacteria are particularly important on exposed surfaces. The cyanobactria distributed on the surface of the stone cultural heritages in Gwanschoksa, Nonsan city were investigated. Chlorococcus sp. Aanabaena sp. Gloeocapsa sp Lyngbya sp. Stigomena sp. Synechocystis sp were identified. Haplaosiphon fontinalis and Stigonema turfaceum, which were not recoded is Korea, were also identified. Cells often have thick pigmented sheath in dry, sun-exposed environment and shorter filament, which can be different than that in aquatic systems. Special attention should be paid to production of an adequate DNA database in order to accelerate the rate at which information on the species present in biofilms become available.

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Tree of life: endothelial cell in norm and disease, the good guy is a partner in crime!

  • Basheer Abdullah Marzoog
    • Anatomy and Cell Biology
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    • v.56 no.2
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    • pp.166-178
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    • 2023
  • Undeniably, endothelial cells (EC) contribute to the maintenance of the homeostasis of the organism through modulating cellular physiology, including signaling pathways, through the release of highly active molecules as well as the response to a myriad of extrinsic and intrinsic signaling factors. Review the data from the current literature on the EC role in norm and disease. Endothelium maintains a precise balance between the released molecules, where EC dysfunction arises when the endothelium actions shift toward vasoconstriction, the proinflammatory, prothrombic properties after the alteration of nitric oxide (NO) production and oxidative stress. The functions of the EC are regulated by the negative/positive feedback from the organism, through EC surface receptors, and the crosstalk between NO, adrenergic receptors, and oxidative stress. More than a hundred substances can interact with EC. The EC dysfunction is a hallmark in the emergence and progression of vascular-related pathologies. The paper concisely reviews recent advances in EC (patho) physiology. Grasping EC physiology is crucial to gauge their potential clinical utility and optimize the current therapies as well as to establish novel nanotherapeutic molecular targets include; endothelial receptors, cell adhesion molecules, integrins, signaling pathways, enzymes; peptidases.

The Effect of Etching Time on the Biaxial Flexural Strength of IPS Empress® 2 Ceramic (불산 처리 시간이 IPS Empress® 2 세라믹의 2축 굴곡강도에 미치는 영향에 대한 연구)

  • Kim, Youn-Hwi;Shin, Soo-Yeon;Cho, In-Ho;Lee, Joon-Seok
    • Journal of Dental Rehabilitation and Applied Science
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    • v.23 no.4
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    • pp.269-281
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    • 2007
  • Fluoric acid etching is an essential procedure in cementation of reinforced ceramics to tooth surface. But there have been few studies about the changes of surface structure and flexural strength of IPS $Empress^{(R)}$ 2 ceramic according to the etching time. The objectives of this study were to examine the surface structure changes and the difference in biaxial flexural strength of IPS $Empress^{(R)}$ 2 ceramic according to various etching times. Sixty one disk-shaped specimens of IPS $Empress^{(R)}$ 2 ceramic($14mm{\times}1.2mm$) were fabricated for the biaxial flexural strength test and SEM analysis according to the manufacturer's recommendations. Sixty specimens were divided into 6 groups(n=10) according to the time of HF acid etching(0, 20, 180 and 300s)and silane/resin cement application. Each disk was loaded using a piston-on-3 ball biaxial configuration in a universal testing machine. The failure loads(N) were recorded, and the biaxial flexural strength for each disk was calculated. A one-way analysis of variance and independent t-test on transformed fracture strength data were used to determine significant differences between groups. The groups of no cementation showed a trend toward progressive weakening with increasing the etching time. However, this was not statistically significant at p=0.05 level. The groups of resin cementation exhibited no apparent trend in their mean strength values. SEM photomicrographs showed very different results of etching. Within the conditions of this study, alteration of surface topography by acid etching does not have a deleterious effect on the biaxial flexural strength of IPS $Empress^{(R)}$ 2 ceramic.