• Journal of the Korean Vacuum Society
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• v.11 no.4
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• pp.201-206
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• 2002

Pd/Si/Pd/Ti/Au ohmic contact to n-type InGaAs was investigated with rapid thermal annealing conditions. Minimum specific contact resistivity of $3.9\times10^{-7}\Omega\textrm{cm}^2$ was achieved at $400^{\circ}C$/20sec. This was related to the formation of Pd-Si compounds by rapid thermal annealing and the in-diffusion of Si atoms to InGaAs surface. However, the specific contact resistivity increased slightly to low-$10^{-6}\Omega \textrm{cm}^2$ at $400^{\circ}C$ for longer than 30 seconds, and to high-$10^{-7}$ at 425~$450^{\circ}C$ for 10 seconds. This resulted from the formation of Pd-Ga compounds. Superior ohmic contact and non-spiking planar interface between ohmic materials and InGaAs were maintained after annealing at high temperature. Therefore, this thermally stable ohmic contact system is a promising candidate for compound semiconductor devices.

• Journal of Korea Water Resources Association
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• v.44 no.3
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• pp.189-198
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• 2011

The aim of this study is to compare k-$\varepsilon$ and k-$\omega$ closures under the condition of oscillatory layer flow at high Reynolds number. A one dimensional vertical model incorporated with flow momentum equations and turbulence models (k-$\varepsilon$ and k-$\omega$) is applied to the laboratory measurements in the turbulent oscillatory boundary layer. The numerical simulation reveals that both turbulence models calculate similar velocity profiles and turbulent kinetic energy (TKE). In addition, both deliver high accuracy under the condition of negligible spanwise pressure gradient. Therefore, it is recommended in this study to use k-$\varepsilon$ closure, of which numerical coefficients have been calibrated from many studies, for the cases of straight channel, estuary, and coastal environment where the spanwise pressure gradient is not significant.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.824-831
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• 1992

Absorption spectra were observed for several Ho(III)-ligand systems in aqueous solution under the changes of ligand concentration and temperature. The intensity change of hypersensitive band $(^5I_8\;\to\;^5G_6)$ was quite remarkable with temperature and concentration, and was interpreted as the change of coordination environments. The transition intensities observed in these spectra were analyzed in terms of the Judd-Ofelt intensity parameters, $\Omega_\lambda$ ($\lambda$ = 2, 4, 6), for 4f $\to$ 4f electric dipole transitions. The $\Omega_2$ parameter was the most sensitive to the temperature and concentration. Using the changes of $\Omega_2$, $Cl^-$ and ${NO_3}^-$ ions were found to form inner sphere complexes in aqueous solution.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.3
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• pp.251-258
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• 2004

The XMT standard is MPEG-4 Scene Description of textual format. It can be utilized to edit the audio/video media for broadcasting and develop the user oriented media contents. This paper proposes XMT authoring system that supports exchange among contents in various presentation environment. The XMT authoring system creates two levels of textual syntax and semantics: XMT-$\alpha$ format and XMT-$\Omega$ format. Because XMT-$\alpha$ and XMT-$\Omega$ have different expression method about an object, the authoring tool offers interface for them. the authoring tool offers interface for them. Also, it defines interior data structure that can support two file formats, and offers the function that transforms XMT-$\alpha$ into BIFS and transforms XMT-$\Omega$ into SMIL or XMT-$\alpha$. It offers interoperability among multimedia data in various environment that is XMT's characteristic.

• Journal of the Korean Vacuum Society
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• v.12 no.3
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• pp.174-181
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• 2003

Ta diffusion barriers have been deposited on Si (100) substrate by applying a negative substrate bias voltage. The effect of the substrate bias voltage on the properties of the Ta films was investigated. In the case of the Ta films deposited without the substrate bias voltage, a columnar structure and small grains were observed distinctly, and the electrical resistivity of the deposited Ta films was very high (250 $\mu\Omega$cm). By applying the substrate bias voltage, no clear columnar structure and grain boundary were observed. The resistivity of the Ta films decreased remarkably and at a bias voltage of -125 V, reaching a minimum value of 40 $\mu\Omega$cm, which is close to that of Ta bulk (13 $\mu\Omega$cm). The thermal stability of Cu(100 mm)/Ta(50 mm)/Si structures was evaluated after annealing in H2 atmosphere for 60 min at various temperatures. The Ta films deposited by applying the substrate bias voltage were found to be stable up to $600^{\circ}C$, while the Ta films deposited without the substrate bias voltage degraded at $400^{\circ}C$.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.183-193
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• 1999

Semiconducting (Sr0.85Ca0.15)TiO3 ceramics were prepared by conventional powder synthesis techniques, and then alkaline metallic cations were diffused into the ceramic bodies. The threshold voltage of the ceramics increases with increasing diffusion time and the amount of diffused materials. The ceramics had boundary potential heights of 0.01 ~ 2.89 eV, while their boundary resistance ranged from 2.2 $M{\Omega}$ to 120.4 $M{\Omega}$. Such electrical characteristics of the boundaries were correlated with the boundary structure of the ceramics obtained by transmission electron microscopy.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.987-990
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• 1999

본 연구에서는 $BaTiO_3$를 기본 조성으로 하여 PTC 써미스터를 제조하였으며 여기에 첨가제로서 Ca, Mn, Nb의 양을 순차적으로 변화시켜 미세구조 및 전기적 특성을 연구하였다. 또한 복소 임피던스 측정을 통해서 PTC 효과에 미치는 주 저항 성분에 대해서 고찰하였다. Ca 첨가 실험에서는 5[mol%] 첨가된 시편에서 $2.3{\times}10^7[\Omega{\cdot}cm]$의 높은 peak 비저항이 나왔으며 Mn과 Nb에서는 각각 0.1[mol%], 0.2[mol%]에서 $1.5{\times}10^8[\Omega{\cdot}cm]$와 $3.71{\times}10^9[\Omega{\cdot}cm]$의 수치가 측정되었다. 또한 Nb 첨가 실험에서는 첨가량이 증가할수록 결정립의 크기가 조밀해지는 현상을 보였다. PTC 효과에 미치는 주 저항 요소에 대해서 관찰한 복소 임피던스 측정에서는 결정립계 저항 성분이 주가 됨을 확인 하였다.

• Journal of the Korean institute of surface engineering
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• v.42 no.3
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• pp.122-127
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• 2009

Ga/Al doped ZnO (GAZO) thin films were prepared on non-alkali glass substrate by co-sputtering system using two DC cathodes equipped with AZO ($Al_2O_3$:2.0 wt%) target and GZO ($Ga_2O_3$:6.65 wt%) target. This study examined the influence of Al/Ga concentration and substrate temperature on the electrical, structural and optical properties of GAZO films. The lowest resistivity $1.95{\times}10^{-3}{\Omega}cm$ was obtained at room temperature. With increasing substrate temperature, resistivity of GAZO film decreased to a minimum value of $7.47{\times}10^{-4}{\Omega}cm$ at below $300^{\circ}C$. Furthermore, when 0.05% $H_2$ gas was introduced, resistivity of GAZO film decreased to $6.69{\times}10^{-4}{\Omega}cm$. All the films had a preferred orientation along the (002) direction, indicating that the deposited films have hexagonal wurtzite structure formed by the textured growth along the c-axis. The average transmittance of the films was more than 85% in the visible light range.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.169-175
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• 2009

In this experiment molybdeum oxide($MoO_3$) films were prepared by a magnetic null discharge(MND) sputtering system and fundamental properties by XRD, XPS and SEM analysis were investigated. The initial and mean insulation resistance of the same with $MoO_3$ film were about 1.4[$M{\Omega}$] and 800[$k{\Omega}$] under the condition of applied voltage of 400[V]. The preferred orientation in the films changed from(100) to (210) with substrate temperature. Two XPS peaks of the $MoO_3$ photoelectron were detected at the binding energies of 228.9[eV] and 232.4[eV], while the binding energy of the O1s peak was 532.6[eV]. The substrate temperature and reactivity gives large effects to the structure and growth of the film and system is also very useful for performing the uniform reactive deposition. It can be found from the result of a $MoO_3$ film deposition that the system is very useful for performing the uniform reactive sputtering.

• Korean Journal of Poultry Science
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• v.22 no.1
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• pp.31-42
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• 1995

This study was to investigate the effects of dietary linoleic acid(18:2\omega6, LA) and aipha-linolenic acid(18:3\omega3. \alpha-LNA) levels on brain development and fatty acid compositions of various lipid classes in the chicken embryo brain tissues. Thirty two ISA Brown layers, 52 weeks-old, were divided into four groups. Birds of each group were given corn-soybean meal based diets added with 1) safflower oil 8%, 2) safflower oil 6% + perilla oil 2%, 3) safflower oil 2% + perilla oil 6%, or 4) perilla oil 8%. Mter 15 days fed the diets. the layers were artificially inseminated to obtain fertile eggs. During the incubation. embryonic brains were sampled at 15th and 21st days. Fatty acid contents were quantitated by using heptadecanoic acid (17:0) as an internal standard. No significant differences in brain weight and in contents of various lipids such as phospholipid. triglyceride, cholesterol. cholesterol ester and free fatty acid in the tissues were found among the dietary groups (P<0.05). The ratios of AA/LA in the brain lipid classes were lowered as the dietary levels of perilla oil were increased. Higher LA was found in phosphatidylcholine(PC) than arachidonic acid (20:4\omega6. AA), meanwhile the level of LA was less than AA in phosphatidylethanolamine(PE). Docosahexaenoic acid(22:6\omega3, DHA) was the* major fatty acid in the tissue and its content in PE was 2.5~3 times higher than in PC. DHA level in the phospholipid reached at a peak (1.7~1.8 mg/brain) in dietary groups added with 6% or 8% perilla oil. suggesting that no more increase in that fatty acid level in the brain tissue could be obtained by consuming more \alpha-LNA, the major precursor of DHA.