• Korean Journal of Materials Research
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• v.11 no.1
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• pp.48-54
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• 2001

The effects of additives in the HCI etching solution on etching behaviors of aluminum foil as dielectric film for electrolytic capacitors were investigated. The etch pits formed in 1M hydrochloric acid containing ethylene glycol as an additive contain more fine and homogeneous etch tunnels compared to those in 1 M hydrochloric acid only, which led to the increase in the effective internal surface area of aluminum foil. After anodizing of aluminum foil etched in etching solutions, the LCR meter results have shown that the capacitance of dielectric film etched in hydrochloric acid with ethylene glycol was increased remarkably compared to that etched in hydrochloric acid only.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.589-596
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• 2002

Tn the data transmission service of the mobile host, it is needed to reduce the bandwidth and to make a reliable error recovery. there are two appropriate methods in that. One is FEC which retransmits the parity of error recovery, in case of happening of the loss after forming the parity of error recovery by grouping original data. The other is local recovery based on server which can block the implosion of transmission. The use of FEC and local recovery based on server at the same time enables the reliable multicast. This paper suggests algorithm that recovers the loss by FEC and local recovery based on server through the solution of the problems about triangle routing, tunnel convergence by dividing mobile host into two parts-the sender and the receiver. This model about the loss of algorithm tested the efficiency of performance by the homogeneous independent loss, the heterogeneous independent loss, the shared source link loss model. The suggested algorithm confirms effectiveness in the environment where there are much data and many receivers in mobile host.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.2
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• pp.53-58
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• 1998

Ekman layer equation with rough-bottom boundary condition has been solved to determine the effect of roughness on the magnitude of Ekman veering. The bottom boundary condition and the flow field were expanded in a power of roughness (h) which is always smaller than the Ekman layer thickness (${\delta}_E$). By changing the magnitude of roughness parameter (h/${\delta}_E$), the magnitude of the veering, which rotates counterclockwise from the interior geostrophic flow, has been computed. At a fixed depth within the Ekman layer, the magnitude of veering increases as the roughness parameter increases. However, the cross-isobar flux turns out to decrease with increasing roughness. To verify the analytic solution, laboratory experiments were carried out. Rough-bottom cylinderical container filled with homogeneous fluid was sit on a rotating table. The flow pattern during the period of steady spin-up shows that the degree of veering coincides well with the analytic results for various roughness parameters.

• Fire Science and Engineering
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• v.26 no.3
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• pp.79-84
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• 2012

In this study thermal characteristics of heat-responsive element considering conduction, convection and rate of change of element using Response Time Index (RTI) applied to sensitivity test of sprinkler head at home and aborad are theoretically investigated. Analytic solution of temperature distributions with radial direction and time is obtained form energy transport equations, non-homogeneous 2th order partial differential equation, applying to constant wall temperature and symmetric condition in order to analyze thermal characteristics of heat-responsive element for circular cylindrical geometry. Base on the results, the analytic method of this study is fundamental data to practical use for sensitivity test of sprinkler head and design of heat-responsive element.

• Progress in Superconductivity
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• v.7 no.2
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• pp.135-139
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• 2006

We fabricated YBCO coated conductors (CCs) by TFA-MOD process and evaluated microstructure, texture formation, and critical temperature ($T_c$) and current ($I_c$). YBCO precursor solution was synthesized using metal-trifluoroacetates and dip coated on $LaAlO_3$(LAO) substrate. The phase formation and microstructure was characterized by X-ray diffraction and scanning electron microscopy (SEM) and the degree of texture was evaluated by pole-figure analysis. The CC was heat-treated in various calcining temperatures ($370^{\circ}C-460^{\circ}C$) and firing temperatures ($750^{\circ}C-800^{\circ}C$). As fired at $775^{\circ}C$ for 4h, the CC had the highest $T_c$ of 89.5 K and $I_c$ of 40 A/cm-width ($J_c=2.0\;MA/cm^2$). Microstructural observation indicated that the YBCO film was dense and homogeneous and had a strong cube texture without formation of second phase and its in-plane full-width at half-maxima; $5.2^{\circ}$ under optimum condition.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.3
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• pp.618-622
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• 2005

Articular cartilage is an important target for studying the arthritic diseases. To verify the therapeutic effects of bee venom herb-acupuncture in vivo, 3${\mu}$l of diluted solution of bee venom for herb-acupuncture were injected into articular cavity once a day during 3 months after making full-thickness defects in rat articular cartilage. Histological examination and immunohistochemistry indicated that the chondrocyte-like tissue was formed during the repair process of cartilage injury, and the expression of a cartilage-specific protein, collagen type II, were significantly activated. It means that the expression of the gene encoding type I collagen was down-regulated, whereas those of collagen type II were up-regulated. Histological examination by hematoxylin-eosin staining indicated that the cells regained their original round morphology. In addition, a homogeneous distribution of articular cartilage extracellular matrices was detected around the cells. These results suggested that bee venom herb-acupuncture was very effective on the recovery of articular chondrocyte phenotype.

• Analytical Science and Technology
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• v.6 no.2
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• pp.197-205
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• 1993

Blends of elemental Ni and 20 weight % Cr powder were milled for different period in a laboratory attritor. Powder size distribution, microstructure and X-ray diffraction characteristics were investigated as a function of processing period. Saturated magnetization, Ms and coercive force, Hc we also measured and compared with plasma melted ingot to confirm the mechanically alloyed states. Mechanical alloying occurred as a consequence of the partition of powders and the increase of interfacial area driving diffusing of Cr into Ni. However, magnetic properties of chemically homogeneous solid solution like melted ingot has not been observed even though steady state of submicron grain size has been achieved after milling over 15 hrs. Further mechanical alloying period gave refinement of grain size, which resulted in the increase of alloyed layer. It is concluded that homogenization should be controlled by the increase of interfacial area between constitutive powders caused by plastic particle deformation and by the diffusion of Cr within the alloyed phase into Ni-rich phase through lattice defects.

• Broadcasting and Media Magazine
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• v.6 no.1
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• pp.78-87
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• 2001

Seven kinds of most representative photorefractive crystals expected to contribute to the realization of the volume holographic storage were reviewed The growth conditions and problems for highly homogeneous optical qualities of the following crystals depending on the growth methods were discussed;(1) $LiNbO_3$ and $Bi_2SiO_{20}$ by Czochralski method (2) $Bi_{12}TiO_{20}$, $KNbO_3$ and $BaTiO_3$ by top seeded solution growth and (3) $(Sr_{1-x}Ba_{x})Nb_{2}O_{6}$ and $(K_{1-y}Na_y)_{2A-2}(Sr_{1-x}Ba_x)_{2-A}Nb_2O_6$ by Stepanov method, And then the figure of merits for the estimation of phororefractive materials on performances, such as $Q_1$, $Q_2$ and sensitivity, were discussed.

• KSBB Journal
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• v.22 no.4
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• pp.244-248
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• 2007

The treatment of a model wastewater containing high concentration, 10 $g/{\ell}$, of phenol in an integrated wet oxidation-aerobic biological treatment was investigated. Partial wet oxidation under mild operating conditions was capable of converting the original phenol to biodegradable organic acids such as maleic acid, formic acid and acetic acid, the solution of which was subjected to the subsequent aerobic biological treatment. The wet oxidation was carried out at 150$^{\circ}C$ and 200$^{\circ}C$ and the initial pH of 1 to 12. The high temperature of 200$^{\circ}C$ and the acidic initial condition in the wet oxidation led to effluents of which biodegradability was higher in the subsequent biological oxidation process, as assessed by chemical oxygen demand (COD) removal. Homogeneous catalyst of $CuSO_4$ was also used for increasing the oxidation rate in the wet oxidation at 150$^{\circ}C$ and initial pH of 3.0. However, the pretreatment with the catalytic wet oxidation resulted in effluents which were less biodegradable in the aerobic biological process compared to those out of the non-catalytic wet oxidation at the same operating conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.979-986
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• 2003

Sintering behavior and electrical properties of CeO$_2$ system were investigated as a function of the amount of Gd:$_2$O$_3$, and Sm$_2$O$_3$, addition. Doped CeO$_2$ consisted of a homogeneous solid solution of the cubic fluorite structure within the amount of addition from 0 mol% to 15 mol%. Grain growth rate of Gd$_2$O$_3$-doped CeO$_2$ was much smaller than that of pure CeO$_2$, while densification rate was considerably larger. Thus doped CeO$_2$ showed a higher density than pure CeO$_2$. The electrical conductivity of Ce$_1$-$_{x}$Sm$_{x}$O$_1$-$_{x}$/2 was increased up to x = 0.2. However, with further increasing dopant concentrations, the magnitude of the conductivity was found to decrease remarkably. The ionic conductivity value obtained at $700^{\circ}C$ for 10 mol% Sm$_2$O$_3$-doped CeO$_2$ electrolyte was 4.6${\times}$10$^{-2}$ S$.$$cm^{-1}$ /.EX> /.