• Applied Chemistry for Engineering
• /
• v.10 no.3
• /
• pp.438-444
• /
• 1999

The natural full-fat rice bran is reported to contain 8.4 to 14.7 wt % Lipids, but the amount and composition of bran depend on the type of rice, quality of paddy, pretreatments to paddy such as parboiling, type of milling system employed, and the degree of polishing. These lipids are usually mixtures of several class fatty acids containing palmitic acid, linolenic acid, linoleic acid, oleic acid, stearic acid, tocopherol, squalene, etc. In this study the oil rich essential fatty acid (EFA) including squalene was extracted from the domestic brown rice bran using supercritical fluid extraction (SFE) and cosolvent induced SFE process, respectively. And the extracts were analyzed with GC-MSD. The extracted amount of rice bran oil was dependent upon the operating pressure and temperature, and the fatty acid composition of oil was varied with the reduced density (${\rho}_{\gamma}$) of supercritical carbon dioxide. About 70~80% of rice bran oil was extracted in 4hrs. The cosolvent induced SFE process shortened the total extraction time, extracted greater amount of oil than SFE process. Especially squalene which was not found in solvent extract phase was identified in SFE and cosolvent induced SFE process.

• Journal of Life Science
• /
• v.24 no.4
• /
• pp.437-446
• /
• 2014

Problems appear when triptans are taken orally. For example, the bioavailability of triptan is reduced by the digestive system, and the drug level in the blood reduces rapidly over time; there is also a possibility of gastrointestinal disorder. To improve side effects, a transdermal patch has been prepared in hydrogel form. The polymer matrix that makes up the hydrogel uses PVA; PEG is used as an additive to induce inter/intra hydrogen bonding of the PVA and almotriptan drug is added. In addition, to accelerate micro-phase separation between PVA chains, liquid nitrogen is used. In FT-IR analysis, the absorption bands of PVA, PEG, and almotriptan were found. The degree of crystallinity, the water uptake ability and tensile strength were increased with increasing PEG content. In drug release tests, the amount of drug released increased depending on the PEG content. In this study, hydrogels with 10 wt% PEG showed better performance in drug release. Approximately 60% of the total drug amount was released in 2 hr, and the drug continued to release for 1 day. Thus, the prepared hydrogel patch is suitable as a transdermal formulation for the second dose administration of triptans to patients who require recurrent migraine treatment within 24 hr after the first administration.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.32 no.4
• /
• pp.203-210
• /
• 2020

Spatial variation of diffracting wave amplitudes along a semi-infinite breakwater is investigated using the analytical solution of Penney and Price (1952) for wave diffraction. On the front side of the breakwater, the fluctuation of wave amplitudes due to diffracting waves would cause a wave force greater than that of superposed incident and reflected waves. The diffracting wave phase varies in circular shape from the breakwater tip of (x, y) = (0, 0) whereas the incident and reflected wave phases vary in planar shape. So, the total wave amplitude of the incident (or reflected) waves and the diffracting waves would fluctuate at a position away from the energy discontinuity line. The position (x, y) = (0, y) on the front and lee sides of the breakwater is at a distance y(π/2 - β) of the point on the energy discontinuity line along the diffracting wave crest line. The degree of reduction of the diffraction wave energy is proportional to the distance from the point on the energy discontinuity line along the diffracting wave crest line. Therefore, the diffracting wave amplitudes on the front and lee sides of the breakwater would be inversely proportional to the square root of y(π/2 - β).

• Journal of the Korean Geophysical Society
• /
• v.10 no.1
• /
• pp.1-12
• /
• 2007

A method to quickly estimate broadband moment magnitudes (Mwp) to warn regional and teleseismic tsunamigenic earthquakes is tested for application of the method to the different seismic observation environment. In this study, the Mwp is calculated by integrating far-field P-wave or pP-wave of vertical component of displacement seismograms in time domain from earthquakes, having magnitude greater than 5.0 and occurred in and around the Korean peninsula from 2000 to 2006. We carefully set up the size of the time window for the computations to exclude S wave phases and other phases following after the P wave phase. The P wave velocities and the densities from the averaged Korean crustal model are used in the computations. Instrumental correction was performed to remove dependency on the seismograph. The Mwp after the instrumental correction is about 0.1 greater than the Mwp before the correction. The comparison of our results to the those of foreign agencies such as JMA and Havard CMT catalogues shows a higher degree of similarity. Thus our results provide an effective tool to estimate the earthquake size, as well as to issue the necessary information to a tsunami warning system when the effective earthquake occurs around the peninsula.

• Corrosion Science and Technology
• /
• v.9 no.4
• /
• pp.147-152
• /
• 2010

Conventional paints for conversion coating applications in steel production derived mainly from water-based polymer dispersions containing several additives actually show good general performance, but suffer from poor scratch and abrasion resistance during use. The reason for this is because the relatively soft organic binder matrix dominates the mechanical surface properties. In order to maintain the high quality and decorative function of coated steel sheets, the mechanical performance of the surface needs to be improved significantly. In fact the wear resistance should be enhanced without affecting the optical appearance of the coatings by using appropriate nanoparticulate additives. In this direction, nanocomposite coating compositions (Nanomer$^{(R)}$) have been derived from water-based polymer dispersions with an increasing amount of surface-modified nanoparticles in aqueous dispersion in order to monitor the effect of degree of filling with rigid nanoparticles. The surface of nanoparticles has been modified for optimum compatibility with the polymer matrix in order to achieve homogeneous nanoparticle dispersion over the matrix. This approach has been extended in such a way that a more expanded hybrid network has been condensed on the nanoparticle surface by a hydrolytic condensation reaction in addition to the quasi-monolayer type small molecular surface modification. It was expected that this additional modification will lead to more intensive cross-linking in coating systems resulting in further improved scratch-resistance compared to simple addition of nanoparticles with quasi-monolayer surface modification. The resulting compositions have been coated on zinc-galvanized steel and cured. The wear resistance and the corrosion protection of the modified coating systems have been tested in dependence on the compositional change, the type of surface modification as well as the mixing conditions with different shear forces. It has been found out that for loading levels up to 50 wt.-% nanoparticles, the mechanical wear resistance remains almost unaffected compared to the unmodified resin. In addition, the corrosion resistance remained unaffected even after $180^{\circ}$ bending test showing that the flexibility of coating was not decreased by nanoparticle addition. Electron microscopy showed that the inorganic nanoparticles do not penetrate into the organic resin droplets during the mixing process but rather formed agglomerates outside the polymer droplet phase resulting in quite moderate cross linking while curing, because of viscosity. The proposed mechanisms of composite formation and cross linking could explain the poor effect regarding improvement of mechanical wear resistance and help to set up new synthesis strategies for improved nanocomposite morphologies, which should provide increased wear resistance.

• Journal of the Korean Chemical Society
• /
• v.38 no.9
• /
• pp.640-652
• /
• 1994

This work is undertaken to determine alcohol homologues so-called fusel oil that may be present in the Korean folk sojues (distilled liquor) made from grains and to describe sample preparation and analytical method by GC-FID-MS. Solid phase extraction method for sample preparation by using porous styrene divinyl benzene polymer (Porapak Q) was compared with steam distillation and solvent extraction method. Retention behaviors of homologous series of alcohols were also studied. Log values of retention time, molecular weight, boiling point, and capacity factor of alcohols showed linear correlations to the carbon number of an alcohol, to the oven temperature, and to the dielectric constant. Components such as methyl alcohol, n-propyl alcohol, isobutyl alcohol, isopentyl alcohol, and phenethyl alcohol have been identified. The more amount of isopentyl alcohol than other alcohols are contained in the Korean folk sojues, while that of n-propyl alcohol are contained in Chinese kaoliangchiew. Degree of similarity or dissimilarity and classification of the individual samples were discussed using multivariate statistical analysis(principal components analysis) based on GC data.

• Korean Journal of Materials Research
• /
• v.22 no.11
• /
• pp.620-625
• /
• 2012

A general synthetic method to make $Fe_3O_{4-{\delta}}$ (activated magnetite) is the reduction of $Fe_3O_4$ by $H_2$ atmosphere. However, this process has an explosion risk. Therefore, we studied the process of synthesis of $Fe_3O_{4-{\delta}}$ depending on heat-treatment conditions using $FeC_2O_4{\cdot}2H_2O$ in Ar atmosphere. The thermal decomposition characteristics of $FeC_2O_4{\cdot}2H_2O$ and the ${\delta}$-value of $Fe_3O_{4-{\delta}}$ were analyzed with TG/DTA in Ar atmosphere. ${\beta}-FeC_2O_4{\cdot}2H_2O$ was synthesized by precipitation method using $FeSO_4{\cdot}7H_2O$ and $(NH_4)_2C_2O_4{\cdot}H_2O$. The concentration of the solution was 0.1 M and the equivalent ratio was 1.0. ${\beta}-FeC_2O_4{\cdot}2H_2O$ was decomposed to $H_2O$ and $FeC_2O$4 from $150^{\circ}C$ to $200^{\circ}C$. $FeC_2O4$ was decomposed to CO, $CO_2$, and $Fe_3O_4$ from $200^{\circ}C$ to $250^{\circ}C$. Single phase $Fe_3O_4$ was formed by the decomposition of ${\beta}-FeC_2O_4{\cdot}2H_2O$ in Ar atmosphere. However, $Fe_3C$, Fe and $Fe_4N$ were formed as minor phases when ${\beta}-FeC_2O_4{\cdot}2H_2O$ was decomposed in $N_2$ atmosphere. Then, $Fe_3O_4$ was reduced to $Fe_3O_{4-{\delta}}$ by decomposion of CO. The reduction of $Fe_3O_4$ to $Fe_3O_{4-{\delta}}$ progressed from $320^{\circ}C$ to $400^{\circ}C$; the reaction was exothermic. The degree of exothermal reaction was varied with heat treatment temperature, heating rate, Ar flow rate, and holding time. The ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was greatly influenced by the heat treatment temperature and the heating rate. However, Ar flow rate and holding time had a minor effect on ${\delta}$-value.

• Korean Journal of Food Science and Technology
• /
• v.29 no.3
• /
• pp.417-426
• /
• 1997

Rice bran protein hydrolysates were prepared and some of their physicochemical properties were investigated to utilize rice bran as starting material for functional food ingredient. Rice bran proteins (RBP) were prepared from defatted rice bran by alkaline extraction and isoelectric precipitation. The enzyme for hydrolysis of RBP was selected through measuring relative activity by pH-drop method and comparing the degree of hydrolysis (DH) of hydrolysates. The enzymatic hydrolysates prepared by $Esperase^{\circledR}$ treatment were partitioned into two fractions by ultrafiltration(UF) with a 10 kDa molecular weight cut-off membrane. Each fraction was applied to a cholic acid-conjugated ${\omega}-aminohexyl$ Sepharose 4B column and the bile acid-binding components were obtained by eluting with deoxycholate. Gel permeation chromatography on a Sephadex G-50 column revealed that molecular weight of the bile acid-binding fraction of UF permeate was distributed in ranges of $2\;kDa{\sim}10\;kDa$ and $0.2\;kDa{\sim}0.6\;kDa$. Three peaks (R-1, R-2 and R-3) were obtained by prep-HPLC of bile acid-binding fraction of UF retentate and analyzed for total and free amino acid composition. The results showed that proline content of the bile-acid binding polypeptides and peptides was four times as much as that of rice bran protein and that the peak corresponding to higher average hydrophobicity had a higher free amino acid content. Average hydrophobicity slightly increased with enzymatic hydrolysis.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.8 no.3
• /
• pp.63-76
• /
• 2004

This paper presents LRB-based hybrid base isolation systems employing additional active/semiactive control devices for mitigating earthquake-induced vibration of a cable-stayed 29 bridge. Hybrid base isolation systems could improve the control performance compared with the passive type-base isolation system such as LRB-installed bridge system due to multiple control devices are operating. In this paper, the additional response reduction by the two typical additional control devices, such as active type hydraulic actuators controlled by LQG algorithm and semiactive-type magnetorheological dampers controlled by clipped-optimal algorithm, have been evaluated bypreliminarily investigating the slightly modified version of the ASCE phase I benchmark cable-stayed bridge problem (i.e., the installation of LRBs to the nominal cable-stayed bridge model of the problem). It shows from the numerical simulation results that all the LRB based hybrid seismic isolation systems considered are quite effective to mitigate the structural responses. In addition, the numerical results demonstrate that the LRB based hybrid seismic isolation systems employing MR dampers have the robustness to some degree of the stiffness uncertainty of in the structure, whereas the hybrid system employing hydraulic actuators does not. Therefore, the feasibility of the hybrid base isolation systems employing semiactive additional control devices could be more appropriate in realfor full-scale civil infrastructure applications is clearly verified due to their efficacy and robustness.

• Journal of Life Science
• /
• v.16 no.4
• /
• pp.555-560
• /
• 2006

A bacterium producing novel lipolytic enzyme was isolated from house sewage and identified as Acinetobacter sp. BD5 based on physiological characterization and 16S rDNA sequencing. The lipolytic activity of Acinetobacter sp. BD5 was tested using an EL agar medium and CE agar medium supplemented with 1% tributyrin and olive oil, respectively. The formation of a clear zone around the colony was detected by agar medium supplemented with 1% tributyrin and olive oil, respectively and Acinetobacter sp. BD5 formed powder-like zone around the colony on LB agar medium containing Tween 20. The quantitative lipolytic activity was determined by using p-NP butyrate as substrate. Acinetobacter sp. BD5 secreted the lipolytic enzyme during exponential growth phase, reaching a maximum amount after 6 hours of incubation. The lipolytic enzyme was found to be optimally active at $60^{\circ}C$ and retained more than 70% at $70-80^{\circ}C$. It displayed a high degree of activity in a pH of 7.0 to 10.6, with an optimal pH of 9.0.