• Korean Journal of Materials Research
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• v.8 no.4
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• pp.288-292
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• 1998

The p*-n ultra shallow junction diode with Co/Ti bilayer silicide was formed by ion implantation of $BF_{2}$ energy : 30KeV, dose : $5\times10^{15}cm^{-2}$] onto the n-well Si(100) region and RTA-silicidation of the evaporated Co($120\AA$)/Ti($40\AA$) double layer. The fabricated diode exhibited ideality factor of 1.06, specific contact resistance of $1.2\times10^{-6}\Omega\cdot\textrm{cm}^2$ and leakage current of $8.6\muA/\textrm{cm}^2$(-3V) under the reverse bias of 3V. The sheet resistance of silicided emitter region, the boron concentration at silicide/Si interface and the junction depth including silicide layer of ($500\AA$ were about $8\Omega\Box$, $6\times10^{19}cm^{-3}$, and $0.14\mu{m}$, respectively. In the fabrication of diode, the application of Co/Ti bilayer silicide brought improvement of ideality factor on the current-voltage characteristics as well as reduction of emitter sheet resistance and specific contact resistance, while it led to a little increase of leakage current.

• Korean Journal of Materials Research
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• v.9 no.6
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• pp.577-582
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• 1999

In order to make the electroconductive $Si_3N_4$-TiN composities, the Si-Ti(N) compacts were nitrided at $1450^{\circ}C$ for 20hours, and then they were post-sintered by a gas-pressure-sintering technique at 1TEX>$1950^{\circ}C$ for 3.5 hours. As starting powders, commercial si powder of about $10\mu\textrm{m}$, two types of Ti powders of 100 and 325 mesh, and fine-sized TiN of $2.5\mu\textrm{m}$ powders were used. In the $Si_3N_4$-TiN sintered bodies used Ti powders, the relative density and fracture strength and electrical conductivity are low due to the existence of large amounts of coarse pores. However, in the $Si_3N_4$-TiN composite used TiN powder, the fracture toughness, fracture strength and electrical resistivity were $5.0MPa{\cdot}m^{1/2}$, 624MPa and $1400{\omega}cm$, respectively. The dispersion of TiN particles in the composite inhibited the growth of $Si_3N_4$ in the shape of rod and made strong strain field contrasts at the $Si_3N_4$-TiNinterfaces. It was recognized that microstructural control is required to improve the electrical conductivity and mechanical properties of $Si_3N_4$-TiN composites by dispersing TiN particles homogeneously.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.684-690
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• 2000

In order to study effects of interfacial layers between $Pb(Zr,Til)Q_3(PZT)$ films and electrodes for Metal-Ferroelectric-MetaI(MFM) structure capacitors, we have fabricated the capacitors with the Pt/PZT/interfacial-layer/Pt/$TiO_2/SiO_2$/Si structure. $PbTiO_3(PT)$ interfacial layers were formed by sol-gel deposition and PbO, ZrO, and $TiO_2$ thin layers were deposited by reactive sputtering. $TiO_2$ interface layers result in the finest grains of PZT(crystalline Temp. $600^{\circ}C$) films compare to $PbO_2\;and\;ZrO_2$ layers. However, as the thickness of $TiO_2$ layer increases. PZT thin films become rough and electrical characteristics were deteriorated due to remained anatase phase. On the other hand. PT interface layers result in improved morphology of PZT films and do not significantly change ferroelectric properties. It is a also observed that seed layers at the middle and top of PZT films do not give significant effects on grain size but the PT seed layer at the interface between the bottom electrode and the PZT films results in the small grain size.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.196-202
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• 1997

Perovskite lanthanum doped lead titanate ($(Pb,La)TiO_{3}$ or PLT) thin films were successfully fabricated on Pt/TijSiO.iSi substrates at the temperatures as low as $440~500^{\circ}C$ by eleclron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR PECVII). Since the volatilities of the MC sources arid oxide molecules (especially Ph oxide) increased with increasing deposition temperature, the film deposition rate and the (I'b + La)/'Ti ratio decreased Stoichiometric perovskite PL'T films with good dielectric and leakeage current properties were obtained at the temperatures of $460~480^{\circ}C$. The lanthanum content of the film was nearly directly propotional to $La(DPM)_{3}$ flow rate. As the La/Ti ratio increased from 3.0 to 9.5%, the dielectric constant increased from 360 to 650 and the leakeage current density at 100kV/cm electric field decreased from $4{\times}10^{-5}$ to $4{\times}10_{-8}A/cm^2$.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.175-179
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• 1997

bliniaturization oi microwave circuit components is an important issue with the development in the mobile communication. Capacitors, inductors anti hybrid devices of these are building blocks of electric circuits, and the fabrication of these devices using thin film technology will influence on the miniaturization of electronic devices In this paper, we report the successful fabrication of the inductors, capacitors and LC hybrid devices using a ferroelectric and a ferromagnetic oxide thin iilm. Au, stable at high temperatures in oxidizing ambient, is patterned by lift-off process, and oxide thin films are deposited by ion beam sputtering and chemical vapor deposition. These devices are characterized by a network analyzer in 0.5-15GtIz range We got the inductance of 5nH, capacitance oi 10, 000 pF and resonant frequencies of $10^{6}-10^{9}Hz$.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.43-49
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• 2008

Purpose: The current study was conducted to evaluate the compatibility of UV-A blocking contact lens on eye protection with regular contact lens. Methods: The protective activity of regular contact lens (UV-A blocking: 20%) and UV-A blocking contact lens (UV-A blocking: 85%) on the denaturation of RNase A, catalase, and superoxide dismutase (SOD) induced UV-A irradiation were compared by acrylamide gel electrophoresis. The enzyme solutions were irradiated with UV-A for 1, 3, 6, 24 and 96 hours at the wavelength of 365 nm. Covering area with contact lenses were varied as 50%, 70% and 100% according to the calculation of blocking areas of anterior eye that could be covered with RGP lens, soft contact lens, and eye glasses, respectively. Results: Denaturations of RNase, catalase and SOD were exaggerated when they were exposed to UV-A for a longer period. The denaturation was effectively prevented by UV-A blocking contact lens compared to regular contact lens. The capability of UV-A blocking contact lens was considerably reduced when the covering area with contact lens decreased and exposure time to UV-A extended. Conclusion: Therefore, it would be suggested that wearing contact lens for a long time under sunlight is carefully considered since the activity of UV-A blocking contact lens against UV-A irradiation may not be enough to protect enzymes presented in eyes when exposure time to UV-A increased.

• Tunnel and Underground Space
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• v.20 no.2
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• pp.82-91
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• 2010

Grouting technology is one of the ground improvement methods used in water controlling and reinforcement of rock mass in underground structure construction. It is necessarily required to find out the characteristics of grout flow through discontinuities in a rock mass for an adequate grout design and performance assessment. Laminar flow is not always applicable in simulating a grout flow in a rock mass, since the rock joints usually have apertures at a micro-scale and the flow through these joints is affected by the joint roughness and the velocity profile of the flow changes partially near the roughness. Thus, the influence of joint roughness and aperture on the grout flow in rough rock joint was numerically investigated in this study. The commercial computational fluid dynamics code, FLUENT, was applied for this purpose. The computed results by embedded Herschel-Bulkley model and VOF (volume of fluid) model, which are applicable to simulate grout flow in a narrow rock joint that is filled with air and water, were well compared with that of analytical results and previously published laboratory test for the verification. The injection pressure required to keep constant injection rate of grout was calculated in a variety of Joint Roughness Coefficient (JRC) and aperture conditions, and the effect of joint roughness and aperture on grout flow were quantified.

• Parasites, Hosts and Diseases
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• v.36 no.3
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• pp.207-212
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• 1998

In the present study, genomic DNAs were purified from Korean isolates (KT8, KT6, KT-Kim and KT-Lee) and foreign strains (CDC85, IR78 and NYH 286) of 1Trichomonas voslnalis, and hybridized with a probe based on the repetitive sequence cloned from T. uqfinolis to observe the genetic differences. By Southern hybridization, all isolates of T. uoSinoLis except the NYH386 strain had 11 bands. Therefore all isolates examined were distinguishable into 3 groups according to their banding patterns; i) KT8, KT6 and KT-Kim isolates had 11 identical bands such as 1 kb, 1.2 kb, 1.6 kb, 1.9 kb, 2.3 kb. 27 kb, 3.2 kb, 2.4 kb, 3.8 kb, 4.9 kb and 6.0 kb, ii) The metronidazole-resistant IR78 strain had the some bands as KT-Lee isolate at bands of 1 kb, 1.2 kb, 1.6 kb. 1.8 kb, 2.1 kb, 2.5 kb, 2.7 kb, 2.9 kb, 3.4 kb, 5.0 kb and 6.0 kb, Bands of CDC85, metronidazole-resistant strain, were similar to those of IR78 and KT-Lee, except that 3.2 kb replaced 2.9 kb. iii) NYH286 particularly had 12 bands and bun patterns were similar to IR78 with a few exceptions as follows; i) 6.2 kb in place of 6.0 kb, ii) 2.0 kb and 2.2 kb instead of 2.1 kb. Through the results obtained, genetic variance of T. uoginnlis isolates was demonstrated by Southern hybridization.

• Parasites, Hosts and Diseases
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• v.33 no.3
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• pp.187-194
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• 1995

The present study aims to observe changing patterns of serum antibody to hleumuvstis calinii in normal rats of different ages and in immunosuppressed rats. The serum IgG antibody was observed by immunoblotting with crude antigen of f carinii which were purified from the lungs of infected rats. The crude antigens separated in SDS-PAGE resolved more than 20 protein bands from 20 to 200 kDa. Of them,40-45, 50-55, 116 and 200 kDa bands were major antigens of R cori.nii. Most of the normal rats of up to 4 weeks had the antibodies reacting the 4 bands, but none of 8-week-old rats revealed the specific antibody. After the rats grew for 40 weeks, all were found to have the antibody in their serum. Same pattern of serum antibody level by age was found in ELISA. When immunosuppressed rats became heavily infected, the antibody in their serum decreased distinctively. The present results suggest that antibodies in normal newborn rats are transferred from their mother and lowered up to 8 weeks. Thereafter, the levels of the antibodies begin to increase by natural exposure to R cnrinii. It was also confirmed that the intensity of P cnrinii infection is inversely related with levels of serum antibodies.

• The Korean Journal of Petroleum Geology
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• v.3 no.1 s.4
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• pp.16-27
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• 1995

The Early Miocene Temblor Formation forms an important sandstone reservoir at Kettleman North Dome oil field, California. Sandstones are mostly arkosic in composition except deepest sandstones containing much volcanic rock fragments. Arranged in paragenetic sequence prior to feldspar alteration, the Temblor sandstones contain cements of early calcite, dolomite, quartz, albite, mixed-layer ohloriteismectite (C/S) and smectite, and anhydrite. Diagenetic changes associated with feldspar are albitization of plagioclase, late calcite and laumontite cementation and grain replacement, plagioclase dissolution, and kaolinite cementation. Plagioclase albitization and late calcite and laumontite cementation in Temblor sandstones occurred at the time of maximum burial with temperatures up to $130^{\circ}C$. Volcanic plagioclases were selectively albitized. Most diagenetic changes are interpreted to have occurred before the maior uplift which occurred within the last one million years ago. Since then to the time of hydrocarbon emplacement plagioclase dissolution and kaolinite cementation occurred. This reaction occurred in relatively closed system due to the occurrence of kaolinite next to the site of plagioclase dissolution. Unaltered part of volcanic plagioclase and plutonic plagioclase which escaped albitization during maximum burial were preferentially dissolved to make plagioclase porosity. Secondary porosity resulting from dissolution of plagioclase and carbonate and anhydrite cements was mainly produced by formation waters containing organic acids released during atagenesis of organic matter.