• Preventive Nutrition and Food Science
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• v.9 no.4
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• pp.346-351
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• 2004

This study was carried out to examine the antioxidant effects of a mixture of mulberry leaves and silkworm powder in plasma and liver of streptozotocin-induced diabetic rats. Sprague-Dawley male rats weighing 100$\pm$10 g were used and their diets were supplemented with $0.4\%$ (4 g/kg) of the mixtures. Experimental groups were diabetic rats without supplements (DM group) or with a combination of the supplements: $100\%$ mulberry leaves (M group), $25\%$ silkworm powder mixed with mulberry leaves (25SM group), $50\%$ silkworm powder mixed with mulberry leaves (50SM group), $75\%$ silkworm powder mixed with mulberry leaves (75SM group) or $100\%$ silkworm powder (100S group). The rats were fed experimental diets and water ad libitum. All animals were injected with streptozotocin at the $3^{rd}$ week for inducing diabetes and were sacrificed on $9^{th}$ day thereafter. Hepatic xanthine oxidase (XOD) activity significantly decreased in the mixture supplemented groups compared to the DM group. Hepatic superoxide dismutase (SOD) activity was not significantly different among any of the experimental groups, but glutathione peroxidase (GSH-px) activity increased in the mixture supplemented groups compared to the DM group. In particular, it was the highest in the 50SM group. The hepatic TBARS values were lower in all the mixture supplemented groups than in the DM group, and it was as lowest when ratio of mulberry leaves to silkworm powder was highest. Hepatic lipofuscin contents were similar with the TBARS value. In conclusion, the mixtures containing silkworm powder reduced oxidative damage by strengtbening the antioxidative system and suppressing oxidative stress in the STZ-induced diabetic rat. The 1:1 blend of silkworm powder and mulberry leaves was the most effective combination for antioxidant activity.

• Preventive Nutrition and Food Science
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• v.18 no.3
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• pp.188-195
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• 2013

Antioxidants are an important group of medicinal preventive compounds as well as being food additives inhibiting detrimental changes of easily oxidizable nutrients. The present investigation has been carried out to evaluate the antioxidant properties of different solvent extracts of Agriophyllum pungens seeds by various in vitro systems. The antioxidative activities of these samples were determined using four methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'- azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, ferric-reducing antioxidant potential (FRAP), and hydroxyl (OH) radical scavenging activities. Additionally, total flavonoids and phenolic contents (TPC) were also determined. Yield of extracts varied widely among solvents and was the highest for water extract (5.642% based on dry weight basis), while ethyl acetate extract exhibited the highest total phenolic content (0.149 mg/mL), total flavonoid content (0.111 mg/mL), and antioxidant activities (P<0.05). The ABTS radical scavenging activity of A. pungens seeds occurred in the following order: ascorbic acid (92.9157%)>BHA (90.1503%)> ${\alpha}$-tocopherol (87.7527%)>APEA (83.9887%) >APWR (75.5633%); the antioxidant activity of the extracts might be attributed to the presence of these phenolics. This suggests that A. pungens seed extract is a potential source of natural antioxidants, which could be added to dietary supplements to help prevent oxidative stress.

• Preventive Nutrition and Food Science
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• v.18 no.4
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• pp.227-233
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• 2013

This study investigated the protective effect of the butanol (BuOH) fraction from fermented Laminaria japonica extract (BFLJ) on AAPH-induced oxidative stress in porcine kidney epithelial cells (LLC-PK1 cells). L. japonica was fermented by Aspergillus oryzae at $35{\pm}1^{\circ}C$ for 72 h. Freeze-dried fermented L. japonica was extracted with distilled water, and the extracted solution was mixed with ethanol and then centrifuged. The supernatant was subjected to sequential fractionation with various solvents. The BuOH fraction was used in this study because it possessed the strongest antioxidant activity among the various solvent fractions. The BuOH fraction of fermented L. japonica had a protective effect against the AAPH-induced LLC-PK1 cells damage and increased cell viability while reducing lipid peroxidation formation and increased activities of antioxidant enzymes such as superoxide dismutase and glutathione peroxidase. The inhibitory effect of BFLJ on lipid peroxidation formation had a higher value of $0.11{\pm}0.01nmol$ MDA at $100{\mu}g/mL$ concentration in comparison with intact BuOH fraction showing $0.22{\pm}0.08nmol$ MDA at the same concentration. Furthermore, BFLJ treatment increased glutathione concentration. GSH concentration in the cell treated with BFLJ of $100{\mu}g/mL$ was $1.80pmol/L{\times}10^5cells$. These results indicate that BFLJ protects the LLC-PK1 cells against AAPH-induced cell damage by inhibiting lipid peroxidation formation and increasing antioxidant enzyme activities and glutathione concentration.

• Journal of the Korea Institute of Building Construction
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• v.4 no.1
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• pp.127-132
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• 2004

CFT(Concrete Filled Steel Tube) is a structure of circular or squared of steel column filled with concrete. The steel tube holds the concrete inside and that makes this structure to perform superior features on stiffness, proof stress, transformation, fire resistance and construction itself. In this study, by over the 800kgf/$\textrm{cm}^2$ of high strength concrete for CFT column, research has been done on the basic property of matter such as fluidity, resistance on segregation, compressive strength, setting icons of the concrete filled in the steel tube under conditions of standard weather. Physical properties of concrete for CFT that Concrete with silica fume, fly ash of air entraining and high-range water reducing agent, that used to CFT column research purpose to find the most ideal composition, which is achieved by the investigation in the concrete's property of matter like ability of Slump, Slump Flow, Air content, Bleeding, and Settlement. For this study, experiments which are bused on obtained the result through physical test are practiced, with all of the experiment, specimens only for control are produced in each method of curing and analyzed to relations with core strength in mock-up test. In mock-up test, the research is studied compactability of concrete filled in tube and degree of hydration hysteresis, as a basic reference for applying to field of CFT column which is used over 800kgf/$\textrm{cm}^2$ high strength concrete.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.04a
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• pp.34-34
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• 1997

The effect of alloying mode and porosity on the axial tension-tension fatigue behavior of a P/M steel of nominal composition Fe-4w/o Ni-1.5w/o Cu-O.5w/o Mo-O.5w/o C has been evaluated. Alloying modes utilized were elemental powder mixing, partial alloying(distaloy) and prealloying by water atomization; in each case the carbon was introduced as graphite prior to sintering. Powder compacts were sintered($1120{\circ}C$/30 min.) in 7Sv/o $H_2$/25v/o $N_2$ to densities in the range 6.77-7.2 g/$cm^3$. The dependence of fatigue limit response on alloying mode and porosity was interpreted in terms of the constituent phases and the pore and fracture morphologies associated with the three alloying modes. For the same nominal composition, the three alloying modes resulted in different sintered microstructures. In the elemental mix alloy and the distaloy, the major constituent was coarse and fine pearlite, with regions of Ni-rich ferrite, Ni-rich martensite and Ni-rich areas. In contrast, the prealloy consisted primarily of martensite by with some Ni-rich areas. From an examination of the fracture surfaces following fatigue testing it was concluded that essentially all of the fracture surfaces exhibited dimpled rupture, characteristic of tensile overload. Thus, the extent of growth of any fatigue cracks prior to overload was small. The stress amplitude for the three alloying modes at 2x$l0^6$ was used for the comparison of fatigue strengths. For load cycles <3x$l0^5$, the prealloy exhibited optimum fatigue response followed by the distaloy and elemental mix alloy, respectively. At load cycles >2x$l0^6$, similar fatigue limits were exhibited by the three alloys. It was concluded that fatigue cracks propagate primarily through pores, rather than through the constituent phases of the microstructure. A decrease in pore SIze improved the S-N behavior of the sintered steel.

• The Korean Journal of Pharmacology
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• v.20 no.2
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• pp.1-6
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• 1984

It has been generally recognized that the secretion of aldosterone is mainly regulated by angiotensin II in animals and humans, however, potassium and ACTH are also proposed as other humoral factors involved in the aldosterone secretory process. Recently, stress, anesthesia, adrenergic stimulation, low sodium intake or water deprivation stimulate plasma renin activity, while high sodium intake and deoxycorticosteroid have been reported to cause suppression of renin activity in animals. It seems that overall response of aldosterone secretory mechanisms reflects complex interactions both intrarenal and extrarenal components. Furosemide has been widely used to investigate the control of renin secretion by the kidney, and the relationship between diuretics and the disposition of endogenous aldosterone were reported (Oh, 1984). The sequential with 10 min interval samples of plasma were collected following administration of furosemide(1 mg/kg), aspirin(10 mg/kg), respectively. And also similar experiment was performed in the propranolol (10 mg/kg) pretreated rabbits. The results were as follows : 1) The concentration of plasma aldosterone was average of $426.I{\sim}485.5pg/ml$ in normal rabbits. Plasma concentrations of aldosterone rised significantly after injection of furosemide during 50 min, and the rise of plasma aldosterone was blocked by the propranolol pretreatment 2) Significant fall in the plasma level of aldosterone after injection of aspirin was noted. This result indicates that the increased secretion of aldosterone induced by furosemide administration is mediated through ${\beta}-receptors$, and the possible role of prostaglandin is substantiated.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.6
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• pp.233-237
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• 2007

Tropical natives (TROP) are capable of tolerating tropical heat because of their long-term adaptation to tropical environments. When exposed to heat stress, these natives tend to respond with lower sweat output, which is generally thought to be the result of heat acclimatization. The main objective of this study was to clarify central mechanisms inherent to suppressed thermal sweating in tropical natives (Malaysians) by comparing their sweating responses to those of temperate native (TEMP) (Koreans). This experiment was conducted in a thermoneutral climatic chamber ($24{\pm}0.5^{\circ}C,\;40{\pm}3%$ relative humidity). Heat loads were applied to each subject by the immersion of their lower legs in a hot water bath ($43^{\circ}C$ for 30 min). Sweat onset-time and sweat volume were compared between TROP and TEMP. The sweat onset-times on four selected points on the body ranged from 10.25 to 13.47 min in TEMP subjects, and from 16.24 to 17.83 min in TROP subjects (p<0.001). The local sweat volumes at the same sites ranged from 4.30 to $9.74 mg/cm^2$ in TEMP subjects, and from between 1.80 to $4.40mg/cm^2$ in TROP subjects (p<0.001). These results demonstrated a significant difference between TROP and TEMP subjects with regard to the manner in which they regulate their body temperatures when exposed to heat loads, and verified that long-term thermal adaptation blunts sweating sensitivities.

• Journal of the Korea Institute of Building Construction
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• v.10 no.2
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• pp.105-113
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• 2010

Method or work type improvement is needed in relation to reducing cost and increasing efficiency by ensuring construction quality and reducing labor in the form work process. This would have a great influence on the entire construction process, and make the process of adopting materials and methods more rational and economic. Hence, this study aimed to develop a Synthetic Resins Euroform that could improve durability, water-proofing, sophistication, and organizational unity through the use of injection modeling. Accordingly, this paper first investigated various performance requirements and necessary techniques, and then verified feasibility by evaluating the physical safety and technical validity when it is applied to construction field. In addition, this study evaluated the constructability, safety performance, environmental performance, and systemic excellence in terms of maintaining convenience of Synthetic Resins Euroform. Moreover, to verify feasibility in the construction field, this study analyzed and evaluated the maximum stress by measuring the load and deformation of the space of the horizontal furring, which is attached to Euroform as an armature.

• Polymer(Korea)
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• v.32 no.6
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• pp.573-579
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• 2008

PBA/PS core-shell polymer nanoparticles were synthesized by two stage emulsion polymerization and hybridized with silica nanoparticle by simple mixing in emulsion state and following precipitation into water/methanol mixture dissolving $Na_2CO_3$. The stress-strain curve revealed that the elastic modulus was increased with increasing molecular weight of polymer and silica weight fraction but decreased with increasing size of core-shell nanoparticle. Especially, there was a rapid increase of elastic modulus with silica blending. As a result, 6 times higher elastic modulus was observed in PBA/PS core-shell baroplastic sample processed at 25$^\circ$C under 13.8 MPa for 5 min by blending with 13.0 wt% of silica nanoparticle.

• Journal of Welding and Joining
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• v.10 no.3
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• pp.63-72
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• 1992

The joining methods of ceramics to metals which can be expected to obtain high temperature strength are mainly classified into the solid-state diffusion bonding method and the active brazing method. Between these two, the solid-state diffusion bonding method is given attentions as substituting method for active brazing method due to being capable of obtaining higher bonding strength at high temperature and accurate bonding. In this paper, the solid-state diffusion bonding of $Al_{2}$O$_{3}$ ceramics to Ni-Cr-Mo alloy steel (SNCM21) using insert metal was carried out. The insert metal employed in this study was experimentally home-made, Ag-Cu-Ti alloy. Influence of several bonding parameters of $Al_{2}$O$_{3}$SNCM21 joint was quantitatively evaluated by bonding strength test, and microstructural analyses at the interlayer were performed by SEM/EDX. From above experiments, the optimum bonding condition of the solid-state diffusion bonding of $Al_{2}$O$_{3}$/SNCM21 using Ag-Cu-Ti insert metal was determined. Futhermore, high temperature strength and thermal-shock properties of $Al_{2}$O$_{3}$/SNCM21 joint were also examined. The results obtained are as follows. 1. The maximum bonding strength was obtained at the temperature of 95% melting point of insert metal. 2. The high temperature strength of $Al_{2}$O$_{3}$/SNCM21 joint appeared to bemaximum value at test temperature 500.deg.C and the bonding strength with increasingtemperature showed parabolic curve. 3. The strength of thermal-shocked specimens was far deteriorated than those of as-bonded specimens. Especially, water-quenched specimen after heated up to 600.deg. C was directly fractured in quenching.