• Food Science and Preservation
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• v.20 no.4
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• pp.546-553
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• 2013

In this study, we examined the antioxidant activity of the Sumaeyaksuk (Artemisia argyi) tea extracts from different pre-treatment and extraction methods. Sumaeyaksuk was sun-dried for 3.5 days (control, RC) and aged at a temperature of $60^{\circ}C$ for 3.5 days (HA), 7 days (HB), and 14 days (HC), respectively. Each sample was extracted in $60^{\circ}C$ and $95^{\circ}C$ hot water for 2 minutes. The soluble solids content of HA from the $60^{\circ}C$and $95^{\circ}C$ hot water extraction were $0.52{\pm}0.18%$ and $0.92{\pm}0.18%$, respectively. The soluble solids content was increased by the higher extraction temperature. The reducing sugar content of RC was $9.55{\pm}0.18mg/g$ in the $95^{\circ}C$ extraction, which was significantly higher than in the $60^{\circ}C$ extracted sample. However, the reducing sugar content did not show a remarkable difference based on aging periods. The total phenolic compound content of the $95^{\circ}C$ extracted samples was $3.36{\pm}0.13{\sim}9.88{\pm}0.23mg/g$, which was significantly higher than that of the $60^{\circ}C$ extracted sample. The ABTS radical scavenging activity of the $60^{\circ}C$ extracted RA and HA samples were 35.63% and 95.10%, respectively. Moreover, the radical scavenging activity increased to 63.35% and 96.78%, respectively, in the $95^{\circ}C$ extracted samples. As a result of the high temperature, the extracted sample showed an increase in the FRAP. In the RC sample, the FRAP was two times higher in the $95^{\circ}C$ extracted sample ($181.28{\pm}2.90{\mu}M$) than in the $60^{\circ}C$ extracted sample ($83.88{\pm}0.43{\mu}M$).

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.177-184
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• 2020

Purpose: The purpose of this study was to compare and evaluate the tensile bond strength of chairside reline resin to denture base resin fabricated by different methods (subtractive manufacturing, additive manufacturing, and conventional heat-curing). Materials and methods: Denture base specimens were fabricated as cuboid specimens with a width of 25 mm × length 25 mm × height 3 mm by subtractive manufacturing (VITA VIONIC BASE), additive manufacturing (NextDent Base) and conventional heat-curing (Lucitone 199). After storing the specimens in distilled water at 37℃ for 30 days and drying them, they were relined with polyethyl methacrylate (PEMA) chairside reline resin (REBASE II Normal). The subtractive and additive manufacturing groups were set as the experimental group, and the heat-curing group was set as the control group. Ten specimens were prepared for each group. After storing all bound specimens in distilled water at 37℃ for 24 hours, the tensile bond strength between denture bases and chairside reline resin was measured by a universal testing machine at a crosshead speed of 10 mm/min. The fracture pattern of each specimen was analyzed and classified into adhesive failure, cohesive failure, and mixed failure. Tensile bond strength, according to the fabrication method, was analyzed by 1-way ANOVA and Bonferroni's method (α=.05). Results: Mean tensile bond strength of the heat-curing group (2.45 ± 0.39 MPa) and subtractive manufacturing group (2.33 ± 0.39 MPa) had no significant difference (P>.999). The additive manufacturing group showed significantly lower tensile bond strength (1.23 ± 0.36 MPa) compared to the other groups (P<.001). Most specimens of heat-curing and subtractive manufacturing groups had mixed failure, but mixed failure and adhesive failure showed the same frequency in additive manufacturing group. Conclusion: The mean tensile bond strength of the subtractive manufacturing group was not significantly different from the heat-curing group. The additive manufacturing group showed significantly lower mean tensile bond strength than the other two groups.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.73-81
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• 2010

The objective of this study was to evaluate the color stability of new silorane-based composite resin compared with methacrylate-based composite resins after immersion in 3 staining solutions. One silorane-based composite(Filtek P90) and 3 methacrylate -based composites(Filtek Z250, Filtek Z350, Tetric Ceram) were evaluated. Twenty disk-shaped specimens($10{\times}2mm$) of each of 4 composite resins were prepared. The specimens were then divided into 4 groups of 5 specimens each and immersed in 3 staining solutions( coffee, red wine, curry solution) or distilled water(control) for 28-day test period. Color of the specimens was measured with a spectrophotometer(Color Eye 7000A) using CIE $L^*a^*b^*$ color space relative to CIE standard illuminant D65 at baseline, 1day, 3days, 7days, 14days, 21days and 28days after staining. The color differences( ${\Delta}{E^*}_{ab}$) were calculated. The results were obtained as follows ; 1. The mean color changes(${\Delta}{E^*}_{ab}$) of the composites were greatest in curry solution, then red wine, coffee and distilled water, in decreasing order. 2. The mean color changes(${\Delta}{E^*}_{ab}$) of the composites were greatest in Z350, Z250, Tetric Ceram and P90, in decreasing order.

• Journal of Life Science
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• v.21 no.12
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• pp.1732-1739
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• 2011

This study was carried out to investigate the effect of lotus root and leaf powder on the quality characteristics of pork patty stored at $3^{\circ}C$ for 9 days. The pork patties were of four types: nothing added(control, T0), 0.5% lotus root powder added (T1), 0.25% lotus root and 0.25% lotus leaf powder added (T2), and 0.5% lotus leaf powder added (T3). The $a^*$ value tended to decrease with longer storage period (p<0.05). The $L^*$ and $a^*$ value of T3 had the lowest value among the samples, the $b^*$ value T2 and T3 were higher than those of T0 and T1 (p<0.05). Water holding capacity decreased with longer storage period (p<0.05), the water holding capacity, cooking loss, increase rate of thickness and decrease rate of diameter were not significantly different among the samples. Hardness and chewiness increased and springiness decreased with longer storage period (p<0.05). The pH creased with longer storage period (p<0.05), but the VBN content not changed during storage. The TBARS values increased with longer storage period (p<0.05), and those of T0, T1, T2 and T3 were 4.57, 1.85, 0.43 and 0.41 mg MA/kg, respectively, after 9 days of the storage. The result suggest that the addition of lotus root and leaf powder at the same time, or addition of lotus leaf powder can be applied to pork patty to its functionality.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.409-414
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• 2009

The aim of this study was to investigate the ameliorating effects of deer antler extract on the learning and memory impairments induced by the administration of scopolamine (2 mg/kg, i.p.) in rats. Tacrine was used as a positive control agent for evaluating the cognition enhancing activity of deer antler extract in scopolamine-induced amnesia models. The results showed that the deer antler extract-treated group (200 mg/kg, p.o.) and the tacrine-treated group (10 mg/kg, p.o.) significantly ameliorated scopolamine-induced amnesia based on the Morris water maze test. Although there was no statistical significance of brain ACh contents among the experimental groups, the brain ACh contents of the deer antler extract-treated group was slightly higher than that of the scopolamine-treated group. The inhibitory effect of deer antler extract on the acetylcholinesterase activity in the brain was significantly lower than that of scopolamine-treated group. The tacrine- and the deer antler-treated groups reduced the MAO-B activity compared to the scopolamine-treated group, but not significantly. These results suggest that the deer antler extract could be an effective agent for the prevention of the cognitive impairment induced by cholinergic dysfunction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1378-1387
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• 2012

To investigate the pharmacological activity of chaga mushroom (Inonotus obliquus) on extraction conditions, chaga was extracted using water (reflux at $50^{\circ}C$, decoction over $90^{\circ}C$, pressure at $121^{\circ}C$) or ethanol (reflux at 50, 70, or $90^{\circ}C$). When water extract was further fractionated into crude polysaccharide (IO-CP), yields of IO-CP (4.8~16.8%) were higher than those of ethanolic extracts (IO-E, 1.9~2.7%) at increased temperature. For antioxidant activity, crude polysaccharide (IO-CP-121) obtained by pressurized extraction showed the highest polyphenolic and flavonoid contents (35.10 mg TAE/g and 18.48 mg QE/g, respectively) as well as DPPH and ABTS free radical scavenging activities (26.08 and 27.99 mg AEAC/100 mg, respectively). Meanwhile, IO-CP-D (decoction) and IO-CP-50 (reflux) had more potent mitogenic effects (2.10- and 1.95-fold of saline control at 100 ${\mu}g/mL$) as well as intestinal immune system modulating activities (6.30- and 5.74-fold) compared to IO-CP-121, whereas ethanolic extracts showed no activity. Although no IO-CP showed cytotoxicity against RAW 264.7 cells at 0.1 mg/mL, IO-CP-121 significantly inhibited TNF-${\alpha}$ and NO production as pro-inflammatory factors in LPS-stimulated RAW 264.7 cells (29.2 and 63.5%, respectively). Ethanolic extracts also showed no cytotoxicity at 0.1 mg/mL, whereas inhibition of TNF-${\alpha}$ and NO production was significantly low compared to that of IO-CP-121. In addition, active IO-CP-D was further fractionated into an unadsorbed (IO-CP-I) and seven adsorbed fractions (IO-CP-II~VIII) by DEAE-Sepharose CL-6B column chromatography in order to isolate immunostimulating polysaccharide. IO-CP-II showed the most potent mitogenic effect and macrophage stimulating activity (4.51- and 1.64-fold, respectively). IO-CP-II mainly contained neutral sugars (61.86%) in addition to a small amount of uronic acid (2.96%), and component sugar analysis showed that IO-CP-II consisted mainly of Glc, Gal, and Man (molar ratio of 1.00:0.55:0.31). Therefore, extraction conditions affect the physiological activity of chaga, and immunostimulating polysaccharide fractionated from chaga by decoction is composed mainly of neutral sugars.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.35-48
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• 2014

In order to estimate the effect of additional nutrients on phytoplankton growth and horizontal phytoplankton community distribution during the autumn season in 2010 and 2011, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas in Gwangyang Bay, Korea. Also, nutrient additional experiments were conducted to assess additional nutrient effects on phytoplankton assemblage using the surface water. In both years, the total nutrients were high at the enclosed inner bay and the mouth of Seomjin River, whereas it was low at the St.15~20 where in influenced by the surface warm water current from offshore of the bay. On the other hand, nano- and pico-sized Chl. a were gradually increased towards the outer bay and their trends were significant in 2011 than in 2010. The cryptophyta species occupied more than 85% of total phytoplankton assembleges in 2010, whereas their abundance in 2011 remainds to be 1/10 levels of 2010. Following the cryptophata species, the diatom Chaetoceros spp. and Skeletonema-like spp. were found to be dominant species. Further the biosaasy experimental results shows that the phytoplankton biomass in the +N and +NP treatments was higher compared to control and +P treatments and its trend was significant at St.8 and St.20 where nutrient concentration were low. Based on the bioassay and field survey, providing the high nutrients may have stimulated to phytoplankton growth such as S. costatum-like spp.. In particular, opportunistic micro-algae such as Cryptomonas spp. were able to achieve the high biomass under the relatively mid nutrient condition from bottom after break down of seasonal stratification in the Gwangyang Bay.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.183-193
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• 2018

Currently, the Korea Atomic Energy Research Institute (KAERI) is planning to build the Ki-Jang Research Reactor (KJRR) in Ki-Jang, Busan. It is important to safely dispose of low-level radioactive waste from the operation of the reactor. The most efficient way to treat radioactive waste is cement solidification. For a radioactive waste disposal facility, cement solidification is performed based on specific waste acceptance criteria such as compressive strength, free-standing water, immersion and leaching tests. Above all, the leaching test is important to final disposal. The leakage of radioactive waste such as $^{137}Cs$ causes not only regional problems but also serious global ones. The cement solidification method is simple, and cheaper than other solidification methods, but has a lower leaching resistance. Thus, this study was focused on the development of cement solidification for an enhancement of cesium leaching resistance. We used Zeolite and Loess to improve the cesium leaching resistance of KJRR cement solidification containing simulated KJRR liquid waste. Based on an SEM-EDS spectrum analysis, we confirmed that Zeolite and Loess successfully isolated KJRR cement solidification. A leaching test was carried out according to the ANS 16.1 test method. The ANS 16.1 test is performed to analyze cesium ion concentration in leachate of KJRR cement for 90 days. Thus, a leaching test was carried out using simulated KJRR liquid waste containing $3000mg{\cdot}L^{-1}$ of cesium for 90 days. KJRR cement solidification with Zeolite and Loess led to cesium leaching resistance values that were 27.90% and 21.08% higher than the control values. In addition, in several tests such as free-standing water, compressive strength, immersion, and leaching tests, all KJRR cement solidification met the waste acceptance or satisfied the waste acceptance criteria for final disposal.

• Journal of the Korean Vacuum Society
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• v.18 no.4
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• pp.318-330
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• 2009

A high heat flux test facility using a graphite heating panel was constructed and is presently in operation at Korea Atomic Energy Research Institute, which is called KoHLT-1. Its major purpose is to carry out a thermal cycle test to verify the integrity of a HIP (hot isostatic pressing) bonded Be mockups which were fabricated for developing HIP joining technology to bond different metals, i.e., Be-to-CuCrZr and CuCrZr-to-SS316L, for the ITER (International Thermonuclear Experimental Reactor) first wall. The KoHLT-1 consists of a graphite heating panel, a box-type test chamber with water-cooling jackets, an electrical DC power supply, a water-cooling system, an evacuation system, an He gas system, and some diagnostics, which are equipped in an authorized laboratory with a special ventilation system for the Be treatment. The graphite heater is placed between two mockups, and the gap distance between the heater and the mockup is adjusted to $2{\sim}3\;mm$. We designed and fabricated several graphite heating panels to have various heating areas depending on the tested mockups, and to have the electrical resistances of $0.2{\sim}0.5$ ohms during high temperature operation. The heater is connected to an electrical DC power supply of 100 V/400 A. The heat flux is easily controlled by the pre-programmed control system which consists of a personal computer and a multi function module. The heat fluxes on the two mockups are deduced from the flow rate and the coolant inlet/out temperatures by a calorimetric method. We have carried out the thermal cycle tests of various Be mockups, and the reliability of the KoHLT-1 for long time operation at a high heat flux was verified, and its broad applicability is promising.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.680-687
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• 1999

To understand the role of shelf sediment in phosphorus biogeochemical cycle, we carried out sequential sediment extraction (SEDEX) of P and porewater analysis on 14 core samples collected in the South Sea of Korea, SEDEX classified P-pools into 5 phases and results are grouped into two categories: reactive P (loosely sorbed-P and Fe bound-P) and refractory P (detrital inorganic-p, authigenic mineral-P and organic-P). Total P concentrations are decreased with sediment depth in all samples as a result of dissolution to porewater. Reactive P comprises about $20\~50\%$ of total P, and iron bound-P is the major form consisting $70\~80\%$ of reactive P-pool. Iron bound-P decreases sharply with depth. Depth profiles of dissolved P concentration in porewater show mirror image of iron bound-P, revealing the role of FeOOH as a regulator of reactive P supply to overlying water column. Authigenic mineral-P consists less than $5\%$ of total P, thus removal of reactive P by converting into refractory P seems inefficient in shelf sediment. This implies that continental shelf sediment sequesters P temporarily rather than permanently. Results show local variation. Nakdong estuary receiving large amount of terrigenous input shows the highest concentration of total P and reactive P. Here iron oxyhydroxides at the surface sediment control the water column flux of P from sediment. Although total P content at the surface is comparable (500$\~$600 ${\mu}g{\cdot}g^{-1}$) between the South Sea and East China Sea, the former contains more iron bound-P and less derital inorganic-P than the latter. Reasons for the difference seem due in part to particle texture, and to biological productivity which depends roughly on the distance from land.