• Polymer(Korea)
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• v.32 no.3
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• pp.199-205
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• 2008

In this study, we fabricated poly (lactide-co-glycolide) (PLGA) scaffold modified with small intestinal submucosa (SIS) as a drug delivery matrix of bioactive molecules. SIS derived from the submucosa layer of porcine intestine has been widely used as biomaterial because of low immune response. PLGA scaffold was prepared by the method of solvent casting/salt leaching. Novel composite scaffolds of SIS/PLGA were manufactured by simple immersion method of PLGA scaffold in SIS solution under vacuum. SEM observation shows that PLGA and SIS/PLGA scaffolds have interconnective and open pores. Especially, SIS/PLGA scaffold showed that micro-sponge of SIS with interconnected pore structures were formed in the pores of PLGA scaffold. In order to assay release profile of proteins, we manufactured FITC conjugated BSA loaded PLGA and SIS/PLGA scaffold. And the release amount was identified by fluorescence intensity using the fluorescence spectrophotometer. The initial burst of BSA containing SIS/PLGA scaffolds was lower than that of PLGA scaffolds resulting in constant release. And release of BSA in SIS/PLGA scaffold was fast and incremental because of the increased content of BSA. In conclusion, we confirmed that penetrated SIS solution prevented the initial burst of BSA and PLGA modified with SIS scaffold is useful as protein carriers with controlled release pattern.

• Korean Journal of Plant Resources
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• v.21 no.5
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• pp.408-412
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• 2008

This research was designed to investigate the antioxidant activities and tyrosinase inhibitory effects of guava (Psidium guajava L.) leaf. Total phenol content was obtained from guava leaf extract of 19.0 (g/100g, D.W.). The crude extract exhibited significantly antioxidant activities (IC50value $102.5{\mu}g/ml$, free radical scavenging; $49.4{\mu}g/ml$, SOD like activity). The crude extract of guava leaf was fractionated into four partition layers; hexane (G-H), ethyl acetate (G-E), butanol (G-B) and water (G-W) layer. The extracts of G-E, G-B, G-W showed high radical scavenging activities of over 50% at $100{\mu}g/ml$. SOD like activities of G-E, G-B, G-W were revealed, as 81.8%, 84.7%, 65.3% at $100{\mu}g/ml$, while those of G-H did not showed the effectively. The crude extract of guava leaf showed high tyrosinase inhibitory effect as 60.8% at 1mg/ml, the measurement of G-E, G-B, G-W were 65.2%, 62.8%, 51.6% and that of G-H was not effective. These results indicate that useful bioactive substances exist in the guava leaf extracts, especially G-E, G-B. And the guava leaf has the potential of being developed into health related products.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1557-1562
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• 1999

As a series of studies on the preservation methods for boiled-dried anchovies, determination of sorption properties and shelf-life prediction were made for the samples. Dried anchovies, which were gamma-irradiated at pre-established dose (5 kGy) after packaging in both a polyethylene film (PE, 0.1 mm) and a laminated film $(nylon\;15\;{\mu}m/polyethylene\;100\;{\mu}m,\;NY/PE)$, were subjected to a quality evaluation during 4 months at different storage conditions, such as $15^{\circ}C/68%\;RH,\;25{\circ}C/75%\;RH,\;and\;35^{\circ}C/84%$ RH. The sample showed 5.47% of BET monomolecular layer moisture content and the corresponding water activity, 0.15. The velocity constants of browning reaction and organoleptic changes in the sample were in proportion to storage temperature, and $Q_{10}$, values were ranged from 2.17 to 2.40 in a given packaging and irradiation conditions. In the shelf-life prediction of the stored sample at $25^{\circ}C$, non-irradiated groups packaged in PE and NY/PE were 84 days and 125 days. While 5 kGy-irradiated groups in the same packaging were 126 days and 138 days, respectively. This finding proved the efficacy of laminated-film packaging and irradiation treatment in preserving the quality of dried anchovies.

• Korean Journal of Food Science and Technology
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• v.11 no.4
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• pp.298-303
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• 1979

The composition of the neutral lipids in the free and bound lipids from four varieties of experimentally cultivated potatoes were identified and quantified by thin layer- and gas-liquid chromatographies. The results were summarized as follows ; 1. The neutral lipids contained in the free and bound lipids were fractionated and identified as esterified sterol, triglyceride, diglyceride, free fatty acid, and free sterol, of which triglyceride and esterified sterol were most abundant. Meanwhile, the triglyceride and esterified sterol contents in the free lipid to the total lipid quantity were 10 and 2.7 % respectively, approximately 3 times higher than the 3.0 and 0.8 % contained in the bound lipid. 2. The fatty acid composition of the neutral lipids in the free and bound lipids was the same as that of the total free and bound lipids. The only difference was that content of saturated fatty acid was lower rate in the neutral lipid of the free lipid than in the total free lipid, whereas the unsaturated fatty acid was more abundant in the neutral lipid of the free lipid. Fatty acid composition of individual neutral lipid was of almost the same pattern as that of the total neutral lipid.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.1-5
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• 2018

In this work, we study the ion conductivity by analyzing the impedance to the high current density range that the PEMFC (Proton Exchange Membrane Fuel Cell) is actually operated. The effect of GDL (Gas Diffusion Layer)presence on impedance was investigated indirectly by measuring hydrogen permeability. When the RH (Relative Humidity)was higher than 60% in the low current range (< $80mA/cm^2$), the moisture content of the polymer membrane was sufficient and the ion conductivity of the membrane was not influenced by the current change. However, when RH was low, ion conductivity increased due to water production as current density increased. The ion conductivity of the membrane obtained by HFR (High Frequency Resistance) in the high current region ($100{\sim}800mA/cm^2$)was compared with the measured value and simulated value. At RH 100%, both experimental and simulated values showed constant ion conductivity without being influenced by current change. At 30~70% of RH, the ionic conductivity increased with increasing current density and tended to be constant.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1638-1643
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• 2018

Multi-layer ceramic capacitors as decoupling capacitor were fabricated by dielectric composition with a high dielectric constant. The fabricated decoupling capacitors were embedded in the PCB of the 10G RF transceiver module and evaluated for the characteristics of electrical noise by the level of AC input voltage. In order to further improve the electrical properties of the $BaTiO_3$ based composite, glass frit, MgO, $Y_2O_3$, $Mn_3O$, $V_2O_5$, $BaCO_3$, $SiO_2$, and $Al_2O_3$ were used as additives. The electrical properties of the composites were determined by various amounts of additives and optimum sintering temperature. As a result of the optimized composite, it was possible to obtain a density of $5.77g/cm^3$, a dielectric constant of 1994, and an insulation resistance of $2.91{\times}10^{12}{\Omega}$ at an additive content of 5wt% and a sintering temperature of $1250^{\circ}C$. After forming a $2.5{\mu}m$ green sheet using the doctor blade method, a total of 77 layers were laminated and sintered at $1180^{\circ}C$. A decoupling capacitor with a size of $0.6mm(W){\times}0.3mm(L){\times}0.3mm(T)$ (width, length and thickness, respectively) and a capacitance of 100 nF was embedded using a PCB process for the 10G RF Transceiver modules. In the range of AC input voltage 400mmV @ 500kHz to 2200mV @ 900kHz, the embedded 10G RF Transceiver modules evaluated that it has better electrical performance than the non-embedded modules.

• The Journal of Engineering Geology
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• v.11 no.2
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• pp.175-190
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• 2001

This study investigates the existing theoretical backgrounds in order to examine the behavior of lateral flow according to the plasticity of soils when unsymmetrical surcharge is worked on polluted soft soils by comparing and analyzing the results measured through model tests. Model tests are canied out as follows soil tank, bearing frame and bearing plate are made. By increasing unsymmetrical surcharge to the ground soils with the consistent water content and with gradually increased polluted materials at intervals, the amounts of settlement, lateral displacement and upheaval were respectively observed. In conclusion, the value of critical surcharge was expressed as q$_{cr}$=2.78$_{cu}$ which was similar to those Tschebotarioff(q$_{cr}$=3.0$_{cu}$) and Meyerhof(q$_{cr}$=(B/2H+$\pi$/2)$_{cu}$) had been proposed. The value of ultimate capacity was expressed as q$_{ult}$=4.84$_{cu}$ which was similar to that of Prandtl. The lateral flow pressure is adeQuately calculated by the eQuation(P$_{max}$=K$_o$ r H) and the maximum value of lateral flow pressure is found near O.3H of layer thickness(H) and is higher to ground surface than the ones in composition pattern, Poulos distribution pattern and softclay soils (CL, CH) which is not polluted. The stability control method used in this research followed the management diagram of Tominaga.Hashimoto, Shibata.Sekiguchi, Matsuo.Kawamura who use the amounts of plasticity displacement by lateral flow. As a result, the ultimate capacity values in the diagram {S$_v$-(Y$_m$/S$_v$)} of Matsuo.Kawamura and in the diagram {(q/Y$_m$)-q} of Shibata. Sekiguchi were smaller than in the ones of load-settlement curve (q-S$_v$).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.6
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• pp.523-531
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• 2008

In hole type CPTu equipment which combines the concepts of inhole test method and piezocone test method was newly developed in order to evaluate the dynamic properties of marine soils. It is possible to perform inhole type CPTu without any additional source device because the source and receiver are contained inside the cone rod, which is different from the conventional seismic cone system. In this study, laboratory tests using kaolinite as soft soil and numerical simulations using finite element method were carried out to investigate the effects of several parameters including test methods and soil conditions on the test results from inhole type CPTu and to find out the optimum test method. It was found that it is necessary to maintain the length of swing arm as well as the distance between source and receiver consistently to obtain the rigorous test results. The laboratory test and numerical results also reveal that contrary to the input wave frequency, the water content of soil layer and the disturbance due to the installation of swing arm apparently affect the shear wave velocity.

• Journal of Animal Science and Technology
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• v.57 no.5
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• pp.17.1-17.6
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• 2015

The present study investigated the nutritional and economic suitability of cashew reject meal (full fat and defatted) as replacement for groundnut cake (GNC) in the diets of laying chickens. A total of eighty four brown shavers at 25 weeks of age were randomly allotted into seven dietary treatments each containing 6 replicates of 2 birds each. The seven diets prepared included diet 1, a control with GNC at $220gkg^{-1}$ as main protein source in the diet. Diets 2, 3 and 4 consist of gradual replacement of GNC with defatted cashew reject meal (DCRM) at 50%, 75% and 100% on weight for weight basis respectively while diets 5, 6 and 7 consist of gradual inclusion of full fat cashew reject meal (FCRM) to replace 25%, 35% and 50% of GNC protein respectively. Each group was allotted a diet in a completely randomized design in a study that lasted eight weeks during which records of the chemical constituent of the test ingredients, performance characteristics, egg quality traits and economic indicators were measured. Results showed that the crude protein were 22.10 and 35.4% for FCRM and DCRM respectively. Gross energy of DCRM was 5035 kcal/kg compared to GNC, 4752 kcal/kg. Result of aflatoxin $B_1$ revealed moderate level between 10 and $17{\mu}g/Kg$ in DCRM and GNC samples respectively. Birds on control gained 10 g, while those on DCRM and FCRM gained about 35 g and 120 g respectively. Feed intake declined (P < 0.05) with increased level of FCRM. Hen day production was highest in birds fed DCRM, followed by control and lowest value (P < 0.05) was recorded for FCRM. No significant change (P > 0.05) was observed for egg weight and shell thickness. Fat deposition and cholesterol content increased (P > 0.05) with increasing level of FCRM. The cost of feed per kilogram decreased gradually with increased inclusion level of CRM. The prediction equation showed the relative worth of DCRM compared to GNC was 92.3% whereas the actual market price of GNC triples that of DCRM. It was recommended that GNC could be completely replaced by DCRM in layer's diets in regions where this by product is abundant. However, FCRM should be cautiously used in diets of laying chickens.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.82-89
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• 1984

These studies were carried out to investigate the effects of rice straw on microflora in relation to nitrogen metabolism in submerged soil. Rice plants were cultured in submerged soil to which rice straw was applied. In the submerged soil applied with rice straw the value of Eh lowered. pH was higher in the upper layer than in the lower. The content of iron(II) in submerged soil increased, while that of ammonium nitrogen decreased when rice straw was applied and nitrate-nitrogen was hardly detected during the rice cultivation period Under application of rice straw the number of denitrifying bacteria observed to increase at the early growing stage of rice plant and to decrease thereafter, and that of nitrate reducing bacteria increased at the late growing stage. The number of ammonium oxidizing bacteria and that of nitrite oxidizing bacteria decreased continually but the latter were rather sharply decreased.