• Journal of Pharmaceutical Investigation
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• v.32 no.1
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• pp.1-6
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• 2002

The mucoadhesive characteristics of [P(AA-co-PEGMM)] films by estimating the glass transition temperature $(T_g)$, analyzing surface energy and studying FT-IR was previously reported. In this study, the possibility of buccal mucoadhesive dosage form of [P(AA-co-PEGMM)] films by mucoadhesive force measurements and dissolution tests were also investigated. Mucoadhesiveness of [P(AA-co-PEGMM)] films was compared with cr-PAA and cr-PEGMM films crosslinked with 3% ethyleneglycol dimethacrylate (EGDMA). The buccal mucoadhesive force of [P(AA-co-PEGMM)] films increased with increasing content of PEGMM. [P{AA-co-PEGMM (18 mole%)}] films showed a significantly greater mucoadhesiveness than cr-PAA and cr-PEGMM films. The mucoadhesive force measured in normal saline (pH 5.0) was higher than that measured in phosphate buffer (pH 6.8) because of the pH dependence of hydrogels with carboxyl ions within the PAA. Moreover, the mucoadhesive force of [P{AA-co-PEGMM (18 mole%)}] films was at maximum after 2 hr attachment of buccal mocosa and it was maintained over $1\;N/cm^2$ for up to 10 hr. In dissolution studies, the release of butorphanol tartrate from [P(AA-co-PEGMM)] films increased with increasing PEGMM content, and films prepared with 18 mole% PEGMM gave almost zero order release kinetics.

• Journal of the Korean Magnetics Society
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• v.13 no.5
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• pp.198-203
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• 2003

To investigate whether the use of hard magnetic film is available to generate bias magnetic field for a magnetoimpedance sensor, the magnetic properties of SmCo hard magnetic films were investigated as a function of their compositions. The saturation magnetization decreased with Sm content increasing in SmCo films. And, the coercive force increased in the extent of Sm content of 28 at%, but decreased as Sm content increased moreover. The bias field effect of SmCo film to amorphous CoZrNb film was investigated with the magnetization corves, permeabilities, and magnetic domain structures of SmCo/CoZrNb multilayers. The bias field of about 60 Oe was observed in the film with 3 mm ${\times}$ 0.5 mm, which can be constructed as a MI sensor, and this result strongly indicates that the bias field generated from a hard magnetic film is adequate to enhance the sensitivity of a MI sensor with hard/soft magnetic multilayer structure.

• Journal of the Korean Electrochemical Society
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• v.6 no.4
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• pp.236-241
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• 2003

Magnetic CoW thin film alloys were electrodeposited from citrate baths to investigate the resulting microstructure and magnetic properties. Deposit tungsten (W) content in the films electrodeposited at $70^{\circ}C$ were independent of current density, while coercivity decreased from hard $(H_{c,//}\~150\;Oe\;and\;H_{c.{\bot}}\;\~240\;Oe)$ to soft magnetic properties $(H_{c,//}\~20\;Oe\;and\;H_{c.{\bot}}\;\~30\;Oe)$ with increasing current densities from $10\;to\;100mA{\cdot}cm^2$, with deposit W content $(\~40\%)$ relatively unaffected by the applied current density. X-ray diffraction analysis indicated that hcp $Co_3W$ phases [(200), (201) and (220) planes] in the CoW films electrodeposited at $70^{\circ}C\;and\;10mA{\cdot}cm^{-2}$ were dominant, whereas amorphous CoW phases with small amount of hcp $Co_3W$ [(002) planes] were dominant with deposition at $70^{\circ}C\;and\;100mA{\cdot}cm^{-2}$. At intermediate current densities $(25\;and\;50mA{\cdot}cm^{-2}),\;hop\;Co_3W$ phases [(200), (002), (201) and (220)] were observed. The average grain size was measured to be 30 nm from Sheller formula. It is suggested that the change of the deposit coercivities in the CoW thin films electrodeposited at $70^{\circ}C$ is attributed to the change of microstructures with varying the current density. Nanostructured $Co_3W/amorphous-CoW$ multilayers were fabricated by alternating current density between 10 and $100 mA{\cdot}cm^{-2}$, varying the individual layer thickness. The magnetic properties of $Co_3W/amorphous-CoW$ multilayers were strongly dependent on the thickness of the alternating hard and soft magnetic thin films. The nanostructured $Co_3W/amorphous-CoW$ multilayers exhibited a shift from low to high coercivities suggesting a strong coupling effect.

• Journal of Korean Elementary Science Education
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• v.27 no.3
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• pp.244-251
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• 2008

One of the problems with testing for the presence of $CO_2$ is that the results are not visible. In order to over-come this weak point, a new testing method was developed with BTB indicator equipment, that made the gas visible. After that, the experiment was performed and tested the effects of the new visible equipment. The visible equipment could be adapted to regular class use successfully. Also, it was effective in that it reduced waste of gas, minimized danger potential through use of $CO_2$ canisters and candle-sticks, and also increased knowledge about indicators. The new experimental method and equipment affected the students' interest. It is possible that the students' positive participation was due to their interest in the new apparatus and application of the visual senses. The new system was tested fer its effects on teaching content and helping to produce sustained memory of the content. There were no significant differences between the groups in terms of content learning on initial content memory. However, when students in both groups were tested 4 months later, the visual experiment group sustained memory performance, while the other group showed a significant decrease. Generally, boys score higher than girls in terms of interest and participation in experimental activities. In this case, however, there were no difference between groups. It may have been due to introduction of new equipment and different methods from the textbooks. So, this could increase participation in science using various experiments.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.8
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• pp.1236-1241
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• 2010

The present study investigated the alcohol fermentation characteristics of citrus fruit hydrolysates for the development of citrus fruit wine with enhanced functionality. The alcohol content of whole citrus (A) and removed peels citrus fruit (B) was 10.13% and 10.83%, respectively. The sugar content of (A) was $12.98^{\circ}Brix$, which was slightly higher than that of (B) ($11.38^{\circ}Brix$), but no significant difference in the alcohol fermentation characteristics was observed. Although the hesperidin content was not largely affected by removed peels the narirutin content of (A) was increased to $281.31\;{\mu}M$, which was significantly higher than that of (B) ($199.05\;{\mu}M$). Thus, the whole citrus was used for fermentation. Investigation of alcohol fermentation characteristics based on yeast type found that the maximum alcohol content was 12.75% when S. bayanus EC-1118 was used. The alcohol content reached 12.40% at an initial acidity of 0.2%, but when the initial acidity was higher than 0.2%, the alcohol content was slightly decreased. At an initial sugar content of $22^{\circ}Brix$, the alcohol content was 11.65%, and the maximum alcohol content of 12.85% was observed when at an initial sugar content of $24^{\circ}$Brix.

• Journal of the Korean Society of Combustion
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• v.19 no.1
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• pp.17-28
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• 2014

In this study, the laminar burning velocity of syngas fuel($H_2/CO$) and flame structure with various hydrogen contents were studied using both experimental measurements and detailed kinetic analysis. The laminar burning velocities were measured by the angle method of Bunsen flame configuration and the numerical calculations including chemical kinetic analysis were made using CHEMKIN Package with USC-Mech II. A wide range of syngas mixture compositions such as $H_2$ : CO = 10 : 90, 25 : 75, 50 : 50, 75:25 and equivalence ratios from lean condition of 0.5 to rich condition of 5.0 have been considered. The experimental results of burning velocity were in good agreement with previous other research data and numerical simulation. Also, it was shown that the experimental measurements of laminar burning velocity linearly increased with the increment of $H_2$ content although the burning velocity of hydrogen is faster than the carbon monoxide above 10 times. This phenomenon is attributed to the rapid production of hydrogen related radicals such as H radical at the early stage of combustion, which is confirmed the linear increase of radical concentrations on kinetic analysis. Particular concerns in this study are the characteristics of burning velocity and flame structure different from lean condition for rich condition. The decrease of OH radicals and double peaks are observed with $H_2$ content in rich condition once $H_2$ fraction exceeds over threshold.

• Membrane Journal
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• v.28 no.4
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• pp.233-242
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• 2018

To study gas membrane using GO (graphene oxide), the PEBAX [poly(ether-block-amide)]-GO polymer composite membrane was prepared by adding GO to PEBAX. Through this composite membrane, gas permeation characteristics for $H_2$, $N_2$, $CH_4$, and $CO_2$ were studied. As a result of the gas permeation test, the permeability of $N_2$, $CH_4$, and $CO_2$ to PEBAX-GO composite membranes gradually decreased as the GO content increased. On the other hand, the gas permeability of $H_2$ increased with the increase of GO content, and it was 21.43 barrer at the GO content of 30 wt%, which was about 5 times higher than that of PEBAX membrane. This is because the GO was easier to operate with a fast and selective gas transport channel for $H_2$ than other gases. The increased selectivity ($H_2/N_2$) and selectivity ($H_2/CH_4$) were influenced by the diffusion selectivity by the permeate gas size. The increased selectivity ($CO_2/N_2$) and selectivity ($CO_2/CH_4$) were more influenced by the solubility selectivity due to the affinity of $CO_2$ and GO for -COOH.

• Journal of the Korean Ceramic Society
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• v.52 no.2
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• pp.154-158
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• 2015

This paper investigates the reaction rates of $CO_2$ that stores carbonation through comparing the carbonation behavior between $Ca(OH)_2$ and fly ash with circulating fluidized bed combustion (CFBC) containing a large amount of free CaO. Because fly ash with CFBC contains abundant free CaO, it cannot be used as a raw material for concrete admixtures; hence, its usage is limited. Thus, it has been buried until now. In order to consider its reuse, we conduct carbonation reactions and investigate its rates. X-ray diffraction (XRD), thermogravimetric/differential thermal analysis (TG/DTA), and X-ray fluorescence (XRF) are conducted for the physical and chemical analyses of the raw materials. Furthermore, we use a PH meter and thermometer to verify the carbonization rates. We set the content of the fly ash of CFBC, $Ca(OH)_2$, $CO_2$ flow rate, and water to 100 ~ 400 g, 30 ~ 120 g, 700 cc/min, and 300 ~ 1200 g, respectively, based on the content of the free CaO determined through the TG/DTA analyses. As a result, the carbonization rate of the fly ash with CFBC is the same as that of $Ca(OH)_2$, and it tends to increase linearly. Based on these results, we investigate the carbonization behavior as a function of the free CaO content contained in the raw material.

• Journal of Magnetics
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• v.12 no.1
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• pp.45-48
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• 2007

[ $Co_{100-X}Zr_X$ ] (x=10-40) alloys were prepared by using a mechanical alloying technique. Phase constitution of the crystallised material depended on the annealing temperature. The $Co_{82}Zr_{18}$ alloy crystallised at lower temperature around $550^{\circ}C$ consisted of $Co_{23}Zr_6$, $Co_5Zr$ and fcc-Co phases, while the alloy crystallised at higher temperature around $800^{\circ}C$ consisted of $Co_{23}Zr_6$ and fcc-Co phases. Phase constitution of the crystallised material also depended on the chemical composition of the alloy. The material with lower Zr content less than 10 at% Zr consisted of $Co_{23}Zr_6$ and fcc-Co, and the material with higher Zr-content over 30 at% consisted of $Co_2Zr$ phase. The material containing 15-20 at% Zr consisted of $Co_{23}Zr_6$, $Co_5Zr$ and fcc-Co. Only the material containing $Co_5Zr$ phase exhibited substantial coercivity, and it was confirmed that coercivity in the mechanically alloyed Co-Zr alloy was originated from the $Co_5Zr$ phase.

• Korean Journal of Materials Research
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• v.2 no.6
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• pp.436-442
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• 1992

When $N_2$was used as shielding gas during the formation of Ti surface-alloyed layer by irradiation of $CO_2$laser beam on steel, TiN and F$e_2$Ti were formed regardness of carbon-content in steel. When Ti content was increased in low carbon-content steel, formation of martensitic structure was suppressed due to increase of critical cooling rate for martensitic transformation. In case of high-carbon steel, even though Ti content was about 1.5% in alloyed layer, hardness was increased by formation of martensitic structure instead of ferrite. In addition to that structure, hardness was incrreased further by precipitation of TiC in Ti alloyed-layer of high carbon-steel.