• 열처리공학회지
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• 제12권1호
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• pp.9-20
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• 1999

The effect of post oxidation, water-quenched after holding in air for 5~420 seconds or cooling or furnace cooling, on corrosion resistance and phase formation characteristics of the surface layer of SM20C and SM45C carbon steels after gas nirtrocarbursing in the $NH_3-5%CO_2-N_2$ gas atmosphere at $580^{\circ}C$ for 3hours is studied. The compound layers of two steels consist of ${\varepsilon}-Fe_{2-3}N$, ${\gamma}^{\prime}-Fe_4N$ and $Fe_3O_4$, phases, however, the quantity of ${\gamma}^{\prime}-Fe_4N$ phase increases for the furnace cooled specimen compared to that of air cooling specimen. With increasing $NH_3$ content in the gas mixture and also increasing the keeping time in the air after gas nitrocarburising, the ${\varepsilon}-Fe_{2-3}N$ phase of compound layer increases, while the decreased current density recognizing the improvement of corrosion resistance are shown. the passive current density of SM45C steel is lower than that of SM20C steel at the same nitrocarburising conditions.

• Macromolecular Research
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• 제12권2호
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• pp.219-224
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• 2004

In this work, we prepared hydrogels for wound dressing from a mixture of poly(vinyl alcohol) (PVA) and alginate using the $\^$60/Co ${\gamma}$-ray irradiation technique. We examined the physical properties of these hydrogels, including gelation, water absorptivity, and gel strength, to evaluate the applicability of these hydrogels for wound dressings. The biocompatibility of these hydrogels was also evaluated in vitro, in cultures of mouse fibroblasts, and in vivo, by subcutaneous implantation studies in rats. The gel content and strength increased upon increasing the radiation dose and upon decreasing the concentration of alginate. The degree of swelling was inversely proportional to the gel content and strength. The degree of cytotoxicity of the ${\gamma}$-ray-treated hydrogels was ca. 60% compared to the (－) control (serum) after 1 day of incubation. When the incubations were prolonged up to 2 days, the toxicity of all the samples decreased remarkably and reached that of the control. Subcutaneous implantation studies in rats indicated that foreign body reactions occurring around the implanted hydrogels were moderate and became minimal upon increasing the implantation time.

• 대한미생물학회지
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• 제6권1호
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• pp.15-20
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• 1971

Brucella melitensis균의 치사량($10^6{\gamma}$)의 Gamma선을 조사해 줌으로써 만든 Vaccine과 가온 또는 화학처치법(ether, formalin, phenol)에 의하여 만든 Vaccine을 생쥐에 접종하여 그 면역성부과능력에 대하여 비교실험 해본 결과, Gamma선 조사에 의하여 만든 Vaccine이 보다 좋은 성적을 가져왔음을 알게 되었다. 생균 Vaccine Brucella-abortus strain 19과 Brucella melitensis의 R-form을 대량 주사 해 주었을때 생쥐에 치명적이었으며, 7종의 adjuvant에 대한 효력비교실험은 Freund's complete adjuvant와 aluminum-potassium sulfate와 pectin을 섞어 만든 adjuvant를 제외하고는 그리 의의있는 차이를 발견하지 못했다.

• Macromolecular Research
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• 제13권2호
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• pp.156-161
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• 2005

The thermal transitions of a nylon 6/layered silicate nanocomposite were studied by differential scanning calorimetry and in-situ synchrotron X-ray diffraction. The drawn film of the nylon 6/layered silicate nanocomposite typically showed three endotherms in the DSC thermogram; a very broad endotherm at $\sim120^{\circ}C(T_{1})$, a double-melting endotherm at $\sim215^{\circ}C(T_{2})$, and a high temperature endotherm at $\sim240^{\circ}C(T_{3})$. The drawn film of the nylon 6/ layered silicate nanocomposite was comprised of a mixture of the $\alpha and \gamma$ forms, with $the \alpha form$ being generated by drawing the pressed film having $the \gamma form$. The melting and crystallization of the crystals were observed at the above thermal transitions during the heating experiment performed at the Pohang X-ray synchrotron radiation source (4C2). The newly generated form was meta-stable and melted $at {\sim}T_{1}$. The double-melting $at {\sim}T_{2}$ was due to the exothermic crystallization of $the \alpha form$ during the main endothermic melting of $the \gamma form$. $The \alpha form$ crystallized $at {\sim}T_{2}$ and melted $at {\sim}T_{3}$.

• Macromolecular Research
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• 제11권3호
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• pp.146-151
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• 2003

The dependence of electrical conductivity on concentrations of diallyldimethylammonium chloride (DADMAC) monomer, linear poly(DADMAC) and their mixture monomer/poly(DADMAC) in dilute aqueous solution exhibits a linear relationship. It was possible to calculate conversion of DADMAC polymerization by measuring its electric conductivity. Although the electrical conductivity of the poly(DADMAC) solution decreased with increasing its molecular weight, in the process of UV or ionizing radiation polymerization the molecular weight of the polymers could be kept constant in the case of fixed temperature, UV-luminous intensity or dose rate. Based on the method mentioned above, the kinetics of UV induced polymerization of DADMAC in aqueous solution was studied; the overall activation energy of polymerization of DADMAC in the water phase was calculated to be 18.8 kJ mol$^{-1}$ . ${\gamma}$-Radiation-induced polymerization of DADMAC in aqueous solution as a function of absorbed dose was studied as well. The conversion of DADMAC increased quickly with dose before 30 kGy and then increased slowly. The experimental data of both UV- and ${\gamma}$-induced polymerization were verified to be reliable by inverted ultracentrifugation method.

• 한국식품영양학회지
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• 제23권2호
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• pp.135-140
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• 2010

Acorns have been used as a traditional remed as well as food source. However, few studies on their immunomodulating effects have been reported. In this study, the combined immunomodulative effect of a water extract of acorns was tested on seven to eight weeks old mice(balb/c). The mice were fed ad libitum on a chow diet, and a water extract of the plant mixture was orally administered every other day for four weeks at two different concentrations(50 and 500 mg/kg B.W.). The production of cytokine(IL-$1{\beta}$, IL-6, IL-2, IL-10, IFN-$\gamma$), secreted by macrophages stimulated with LPS or not, detected by ELISA assay using cytokine kit. After 48 h of incubation with mitogen(ConA or LPS) ex vivo study showed that cytokine (IL-$1{\beta}$, IL-6, IL-2, IL-10, IFN-$\gamma$) was detected in both of the 50 and 500 mg/kg B.W. supplementation groups with LPS stimulation. The results of this study may suggest that supplementation with acorn water extract increase immune function by regulating cytokine production capacity by activated macrophages.

• 약학회지
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• 제43권3호
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• pp.300-305
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• 1999

A sensitive and efficient assay method was applied to determine the level of glutamic acid (GA) and ${\gamma}-aminobutyric$ acid (GABA) in frontal cortex and hippocampus of rat administrated with ethanol and drugs. The compounds were derivatized with ο-phthalaldehyde (OPA) and 2-mercaptoethanof for precolunm analysis. The condition for the simultaneous determination of GA, GABA and $\beta-aminobutyric$ acid (BABA) by high performance liquid chromatography with electrochemical detection was reverse phase $C_{18}$ column as stationary phase, 0.1 M phosphate buffer containing 0.1 mM $Na_4EDTA$ : methanol = 55:45 (v+v) pH 3.8 as mobile phase and 0.7V electrode voltage. The stability of reaction product of GA, GABA and BABA with OPA could be increased by adding the same volume of polyethylene glycol 400 to reaction mixture. The GABA level in frotal cortex of rat was significantly decreased by the administration of picrotoxin and diazepam, but it was significantly increased by the administration of red ginseng total saponin, N-methyl-D-glucamine and (-)-deprenyl.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.310-317
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• 2022

The mass attenuation coefficient is the primary physical parameter to model narrow beam gamma-ray attenuation. A new machine learning based approach is proposed to model gamma-ray shielding behavior of composites alternative to theoretical calculations. Two fuzzy logic algorithms and a neural network algorithm were trained and tested with different mixture ratios of vanadium slag/epoxy resin/antimony in the 0.05 MeV-2 MeV energy range. Two of the algorithms showed excellent agreement with testing data after optimizing adjustable parameters, with root mean squared error (RMSE) values down to 0.0001. Those results are remarkable because mass attenuation coefficients are often presented with four significant figures. Different training data sizes were tried to determine the least number of data points required to train sufficient models. Data set size more than 1000 is seen to be required to model in above 0.05 MeV energy. Below this energy, more data points with finer energy resolution might be required. Neuro-fuzzy models were three times faster to train than neural network models, while neural network models depicted low RMSE. Fuzzy logic algorithms are overlooked in complex function approximation, yet grid partitioned fuzzy algorithms showed excellent calculation efficiency and good convergence in predicting mass attenuation coefficient.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.477-484
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• 2024

Experimental investigations on gamma - rays attenuation parameters and dielectric spectroscopic properties were done on a polymeric mixture with chemical composition (100-x) polyethylene + x basalt, where x = 0, 1, 3, 5, 10, and 20 wt%. Using the melting blending technique,six nanocomposite polymeric samples were prepared. The linear attenuation coefficient µ of each prepared set of samples was measured using a gamma-ray spectrometer including High Purity Germanium detector (HPGe) at energies 662.5, 1173.24, and 1332.51 keV. Based on the measured values of (µ) and sample density, the other effective shielding parameters were calculated. The values of µ showed an increase with increasing the dopant ratios from 0.0 up to 20.0 wt%. In addition, the µ values decreased with the photon's energy. The µ values were found 0.0847 up to 0.1175 cm^-1, 0.0571 up to 0.0855 cm^-1, and 0.0543 up to 0.075 cm^-1 at 662.5, 1173.24, and 1332.51 keV. for B0 up to B20, respectively. The ATR spectroscopy was done on the prepared samples, and a good evidence of adding the filler to the pure polyethylene (HDPE) was obtained. Besides, an enhancement in dielectric constant by insertion of basalt NPs also recorded and can be attributed to the large dielectric constant of basalt compared to pure HDPE.

• 한국환경농학회지
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• 제34권2호
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• pp.98-104
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• 2015

BACKGROUND: ${\gamma}$-Oryzanol, a mixture of ferulic acid esters of triterpene alcohols and sterols, are a nutritionally important group of rice secondary metabolites. The ${\gamma}$-Oryzanol content and composition were found to vary with enviromental factors such as growth temperature, varietal origin, and cultivation method. Therefore, the effect of green manure treatments will be also be an important factor in their content. METHODS AND RESULTS: The ${\gamma}$-Oryzanols extracted using dichloromethane/methanol were analyzed equipped liquid chromatography with a diode array detector. A total of ten components of ${\gamma}$-oryzanol including ${\Delta}7$-stigmastenyl ferulate were isolated of which, cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, campesteryl ferulate and sitosteryl ferulate were identified as the major components in Korean rice variety, Unkwang. The ${\gamma}$-oryzanol content in rice, in the presence of nitrogen fertilization using green manure was similar to conventional nitrogen fertilization, but was higher than the control(no fertilizations). The ${\gamma}$-oryzanol ontent in rice, in the presence of hairy vetch as green manure crop was the highest compared to other crops (opium-poppy, crimson clover, cornflower). As a result of PLS-DA using SIMCA 11.0 ver. as multivariate analysis program on the basis of total data, in all samples, the specific pattern and cluster of ${\gamma}$-oryzanol scores according to green manure crops and conditions were confirmed with possible distinguishing nitrogen effects. CONCLUSION: The nitrogen contained in the green manure crops is considered to play a major role in the formation of ${\gamma}$-oryzanol. Hairy vetch which contains higher nitrogen increased the concentration of ${\gamma}$-oryzanol in rice.