• Title/Summary/Keyword: 이온절단

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Proton implantation mechanism involved in the fabrication of SOI wafer by ion-cut process (Ion-cut에 의한 SOI웨이퍼 제조에서의 양성자조사기구)

  • 우형주;최한우;김준곤;지영용
    • Journal of the Korean Vacuum Society
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    • v.13 no.1
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    • pp.1-8
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    • 2004
  • The SOI wafer fabrication technique has been developed by using ion-cut process, based on proton implantation and wafer bonding techniques. It has been shown by TRIM simulation that 65 keV proton implantation is required for the standard SOI wafer (200 nm SOI, 400 nm BOX) fabrication. In order to investigate the optimum proton dose and primary annealing condition for wafer splitting, the surface morphologic change has been observed such as blistering and flaking. As a result, effective dose is found to be in the 6∼$9\times10^{16}$ $H^{+}/\textrm{cm}^2$ range, and the annealing at $550^{\circ}C$ for 30 minutes is expected to be optimum for wafer splitting. The depth distribution of implanted hydrogen has been experimentally confirmed by ERD and SIMS measurements. The microstructure evolution in the damaged layer was also studied by X-TEM analysis.

Analysis of rutile single crystals grown by skull melting method (Skull melting법에 의해 성장된 rutile 단결정 분석)

  • Seok, Jeong-Won;Choi, Jong-Koen
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.16 no.5
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    • pp.181-188
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    • 2006
  • Rutile single crystals grown by skull melting method were cut parallel and perpendicular to growth axis, and both sides of the cut wafers (${\phi}5.5mmx1.0mm$) were then polished to be mirror surfaces. The black wafers were changed into pale yellow color by annealing in air at 1200 and $1300^{\circ}C$ for $3{\sim}15\;and\;10{\sim}50$ hours, respectively. After annealing, structural and optical properties were examined by specific gravity (S.G), SEM-electron backscattered pattern (SEM-EBSP), X-ray diffraction (XRD), FT-IR transmittance spectra, laser Raman spectroscopy (LRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). These results are analyzed increase of weight in air, decrease of weight in water and specific gravity, shown secondary phase of needle shape, diffusion of oxygen ion and increase of $Ti^{3+}$. From the above results, we suggest that the skull melting method grown rutile single crystals contain defect centers such as $O_v,\;Ti^{3+},\;O_v-Ti^{3+}$ interstitials and $F^+-H^+$.

REMINERALIZATION DEPTH OF CPP-ACP ON DEMINERALIZATION HUMAN ENAMEL IN VITRO (탈회된 법랑질에서 CPP-ACP의 재광화 깊이)

  • Choi, Han-Ju;Choi, Yeong-Chul;Kim, Kwang-Chul;Choi, Sung-Chul
    • Journal of the korean academy of Pediatric Dentistry
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    • v.35 no.2
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    • pp.278-286
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    • 2008
  • Many studies regarding Casein phosphopeptides-amorphous calcium phosphate(CPP-ACP) have demonstrated the remineralization ability on the demineralized enamel surface. A question is still remained that how deep can the calcium (Ca) and phosphorus (P) ions supplied by the CPP-ACP paste penetrate into the enamel subsurface. The aims of this study were to measure the penetrating depth of Ca and P ions in the demineralized human enamel in vitro, and were to determine the amount and depth of Ca and P ions according to the duration. The amount and depth of Ca and P ions were measured by microscopic observation with Field Emission Scanning Electron Microscopy (FE-SEM; LEO SUPRA 55, Carl Zeiss, Germany) and Energy Dispersive X-ray Spectrometer (EDS; GENESIS 2000, EDAX, USA: Linescan of Calcium and Phosphorus). Freshly extracted four human 1st premolars were obtained from the Dept. of Pediatric Dent., Kyung Hee Univ. Buccal surfaces of the 1st premolars were covered with nail varnish to form a window on the middle third of buccal surface. All of the teeth with enamel windows were immersed in a solution of 0.1 M lactic acid, Carbopol C907 (carboxypolymethylene BF Goodrich, Cleveland, OH, USA) at pH 4.8, and then incubated for 7 days. Each tooth crown was sawn in half through the midline of buccal window along the long axis of premolar. The four blocks of premolars were immersed in a 10-times diluted solution of CPP-ACP paste (Tooth Mousse, GC Corp., Tokyo, Japan) for 1, 2, 3 and 5 weeks while the rests were immersed in a placebo solution (distilled water) for the same duration. Each specimen was embedded in epoxy resin, and was sectioned perpendicular to the window, using a water-cooled diamond blade saw. The spectrum density indices of Ca and P were measured in the sound, de- and remineralized enamels by FE-SEM and EDS. The Student's t test was performed to compare the Spectrum Density Indices (SDI) of sound, re-and demineralized enamels, and to compare the differences among the durations. Followings are the conclusion : 1. The penetration depth of the remineralizing ions (Ca & P) of CPP-ACP paste is related to the depth of demineralized enamel (approximately $1050{\sim}1350{\mu}m$). It is revealed that the penetration depth of both ions reaches full thickness of decalcification and even slightly into the sound enamel. 2. The Ca & P levels of remineralized enamels in 1, 2 weeks were significantly higher than those of the sound enamels (p<0.05). 3. No statistically significant difference of Ca & P levels was found in relation with the increasing duration of remineralization (p>0.05).

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Studies on the Synthesis of Polymer Metal Complex and Its Application to Organic Reactions (고분자 금속촉매의 합성과 유기합성 반응에의 활용에 관한 연구)

  • Kyu Ja Hwang;Young Ju Kim;Yong Keun Lee
    • Journal of the Korean Chemical Society
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    • v.30 no.5
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    • pp.449-455
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    • 1986
  • Various polymer metal complexes have been synthesized from anhydrous $AlCl_3,\;FeCl_3,\;SbCl_5,\;SnCl_4\;and\;ZnCl_2$ with cation exchange resin in carbon disulfide solvent. The forms of the surfaces and sectioned beads of these polymer metal complexes have been observed using scanning electron probe microanalyzer. To examine the catalytic activity of polymer metal complexes, the esterification of various dibasic acids with alcohols have been carried out. Polymer metal complexes were found to be the effective catalyst for esterification of dibasic carboxylic acids.

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Growth of Nd:YAG single crystal by czochralski method and characteristics of laser generation (Czochralski 방법에 의한 Nd : YAG 단결정의 육성 및 레이저 출력특성)

  • 이상호;김한태;배소익;정수진
    • Korean Journal of Optics and Photonics
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    • v.9 no.3
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    • pp.175-180
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    • 1998
  • Nd:YAG single crystal widely used as solid state laser was grown by Czochralski method. <111> single crystal with 0.9at% of $Nd^{3+}$ was grown from the Czochralski furnace with a automatic diameter control system. The vertical temperature gradient in the liquid was the major factor that influence the crystal quality, and the crystal diameter was controlled by the home made computer program. The crystal boule with $\phi$50mm$\times$ι100mm effective size was cut, polished, and antireflection coated. The optical evaluation such as absorption spectrum, fluorescence spectrum coincide with typical features of Nd:YAG single crystal. The laser rod was assembled into the CW laser generator with a Kr lamp. The maximum CW laser output was 70 W and the threshold power and efficiency was 1.3kW and 1.64% respectively.

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Beam stability improvement of liquid metal ion source (액체 금속 이온원의 빔 안정도 향상)

  • Hyun J. W.;Yim Youn Chan;Kim Seuong Soo;Oh Hyun Joo;Park Cheol Woo;Lee Jong Hang;Choi Eun Ha;Seo Yunho;Kang Seung Oun
    • Journal of the Korean Vacuum Society
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    • v.13 no.4
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    • pp.182-188
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    • 2004
  • Previous studies on the liquid Gallium ion sources used an electro-chemically etched tungsten wire with a coil-type heater. Such a structure requires excessive power consumption in the course of heating the liquid metal. In this work, a new structure is proposed that replaces the coil-type heater. It uses a Gallium reservoir made of six pre-etched 250$\mu\textrm{m}$ tungsten wires that surround the needle electrode. Gallium trading at the reservoir is observed to be much more stable, resulting in an improved beam stability.

Nucleophilic Substitution at a Carbonyl Carbon Atom (X). Nucleophilic Substitution Reactions of N,N-Disubstituted Carbamoyl Chlorides (카르보닐탄소원자의 친핵성 치환반응 (제10보). N,N-이치환 염화카르바모일의 친핵성 치환반응)

  • Shi Choon Kim;Ho Bong Song;Ikchoon Lee
    • Journal of the Korean Chemical Society
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    • v.23 no.6
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    • pp.368-373
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    • 1979
  • Kinetic studies have been carried out on solvolyses and halide exchanges $(Cl^-,\;Br^-,\;I^-)$ of N,N-dimethyl-, N,N-diethylcarbamoyl chlorides, and solvolyses of N,N-diphenylcarbamoyl chloride. Kinetic results together with simple MO analysis indicated that: (a) N,N-dialkylcarbamoyl chlorides reacted via the $S_N2$ mechanism, while N,N-diphenylcarbamoylchloride reacted via the $S_N1$ mechanism; (b) in chloride exchanges, the bond-breaking appeared to be important, whereas in bromide and iodide exchanges, the bond-formation was shown to be important.

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Thermo-reversible Crosslinking Elastomer through Supramolecular Networks (초분자 네트워크를 이용한 열가역성 가교 탄성체)

  • Bae, Jong-Woo;Oh, Sang-Taek;Kim, Gu-Ni;Baik, Hyen-Jong;Kim, Won-Ho;Choi, Sung-Seen
    • Elastomers and Composites
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    • v.45 no.3
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    • pp.165-169
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    • 2010
  • Recently supramolecular network thermo-reversible crosslinking elastomer having flexibility, various functionality, and advantages of thermoplastic elastomer (TPE) such as recycle and easy processbility is introduced. Although thermo-reversible bonds such as hydrogen bond and ionic cluster is recognized as a common technology since 1990, control technology of bonding and dissociation of crosslink in supramolecular network is a recent technology. In this review, characteristics of thermo-reversible crosslinking elastomer having rheological properties of TPE and reinforcing behaviors of thermoset elastomer are summarized.

Microfluidic System for the Measurement of Cupric Ion Concentration using Bilayer Lipid Membrane on Silver Surface (은 표면의 이중층 지질막에 의한 구리 이온 농도 측정용 마이크로플루이딕 시스템)

  • Jeong, Beum Seung;Kim, Do Hyun
    • Korean Chemical Engineering Research
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    • v.48 no.1
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    • pp.33-38
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    • 2010
  • A microfluidic system has been developed using biomaterial for the measurement of cupric ion concentration. The cell-membrane-mimicking bilayer lipid membrane(BLM)-coated silver electrode was used for the sensing of cupric ion concentration. The silver-supported BLM could increase its stability. A silver-supported bilayer lipid membrane(s-BLM) was easily obtained using its self-assembling characteristics by immersing silver wire into lipid(phosphatidylcholine; PC) solution and then dipping into aqueous KCl solution. These s-BLMs were used to determine the relationship between $Cu^{2+}$ concentration and current crossing s-BLM. Their relationship showed high linearity and reproducibility. The calibration curve was constructed to express the relationship between $Cu^{2+}$ concentration and current in the $Cu^{2+}$ concentration range of 10 and $130{\mu}M$. This calibration curve was used to measure $Cu^{2+}$ concentration in an unknown sample. Microfluidic system with s-BLM was made of PDMS(polydimethyl siloxane) using typical soft photolithography and molding technique. This integrated system has various functions such as activation of the silver surface without cutting silver wire, coating of BLM on silver surface, injection of KCl buffer solution, injection of $Cu^{2+}$ sample and measurement of $Cu^{2+}$ concentration in the sample.

Transport Coefficients and Effect of Corrosion Resistance for SFRC (강섬유 보강 콘크리트의 수송계수 및 부식저항효과)

  • Kim, Byoung-Il
    • Journal of the Korea Concrete Institute
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    • v.22 no.6
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    • pp.867-873
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    • 2010
  • This study investigated the corrosion properties of reinforced concrete with the addition of steel fibers. The transport properties of steel fiber-reinforced concrete such as permeable void, absorption by capillary action, water permeability and chloride diffusion were first measured to evaluate the relationship with the corrosion of steel rebar. Test results showed a slight increase on the compressive strength with the addition of steel fibers as well as considerable improvement of penetration resistance to mass transport of harmful materials into concrete. The addition of steel fibers in reinforced concrete accelerated the initiation of steel corrosion contrary to the expected results based on the measured transport properties. The NaCl ponding surface showed the spalling failure due to the corrosion expansion of steel fibers and the cut-surface around the steel rebar showed the localized steel fiber's corrosion. The wet-dry cycling with high chloride ions as well as high temperature seems to induce the increase of salt crystallization on the pores continually and the increased pressure with the steel fiber's corrosion on the pores caused the spalling failure on the exposed surface. The microcracking on the surface therefore accelerated the movement of water, chloride ions and oxygen into the embedded steel rebar. The mechanism affecting corrosion of embedded steel reinforcement with steel fibers in this study are not yet fully understood and require further study comprising of accurate experimental design to isolate the effect of steel fiber's potential mechanism on the corrosion process.