• Journal of Technologic Dentistry
• /
• v.21 no.1
• /
• pp.27-41
• /
• 1999

The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-30Pd-10Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at 350-$550^{\circ}C$ Age-hardening characteristic of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, energy dispersed spectra and electron probe microanalysis. Principal results are as follows ; Maximum hardening occured in two co-phases of ${\alpha}_2$ + PdCu In stage II, decomposition of the $\alpha$ solid solution to a PdCu ordered phase($L1_o$ type) and an Ag-rich ${\alpha}_2$ phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu redered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was ${\alpha}{\to}{\alpha}_1+PdCu{\to}{\alpha}_2+PdCu$ at Pd/Cu = 3 Pd element of Ag-Pd-Cu alloy is more effective dental alloy on anti-corrosion and is suitable to isothermal ageing at $450^{\circ}C$.

• Korean Journal of Organic Agriculture
• /
• v.25 no.1
• /
• pp.71-84
• /
• 2017

Hot pepper growth in no-tillage cultivation on recycled ridge was increased by 22% compared with tillage cultivation. At 3 years after no-tillage cultivation, hot pepper growth was increased by 12% compared with tillage cultivation. Dry weight of unripe hot pepper at 2 years of no-tillage cultivation was 348.4 kg/10a increasing 16% compared with tillage cultivation while dry weight of unripe hot pepper was decreased at 3 years of no-tillage cultivation. Bacteria flora at 2 years of no-tillage cultivation was significantly increased compared with tillage cultivation. Bacteria flora was not significantly different at 3 years of no-tillage cultivation. Actinomyces flora at 2 years of no-tillage cultivation was significantly increased compared with tillage cultivation. Actinomyces flora was decreased at 3 years of no-tillage cultivation. Fungi flora at 2 and 3 years of no-tillage cultivation was increased by 1.3 and 1.7 times respectively, compared with tillage cultivation. Generation amount of carbon dioxide at no-tillage cultivation soil was remarkably decreased by 41% compared with tillage cultivation. Population of animalcule in early stage of hot pepper soil was 2 species and 6 individuals on Collembola and Acari at tillage cultivation. Population of animalcule in hot pepper soil was 5 species and 11 individuals including Chilopode at one year of no-tillage cultivation. Population of animalcule in hot pepper soil was 3 species and 5 individuals including Coleoptera and Chilopode at 2 years of no-tillage cultivation. Population of animalcule was 4 species and 40 individuals including Hypogastrurigae and 8 species and 97 individuals including Earwig (Labidura japornica) at 46 days after transplanting on tillage cultivation. Population of animalcule was 9~10 species and 101~107 individuals on no-tillage cultivation. Nature status for environmental change as index organism was 19 points and 33 points, at tillage and no-tillage cultivation, respectively. These results indicate that no-tillage agriculture of korean-style on recycled ridge plays a very important roles on pepper growth, biodiversity of animalcule, and greenhouse gases at plastic film greenhouse soil in no-tillage systems.

• Journal of radiological science and technology
• /
• v.11 no.1
• /
• pp.71-77
• /
• 1988

To improve the storage method for kimchi, optimal ripening kimchi was irradiated with doses of 1, 3, 5kGy Co-60gamma radiation, followed by the microbiological, physicochemical and senosory evaluations during storage at $5^{\circ}C$. 1. Total aerobic count increased in the beginning of storage and then decreased slowly as the number of total lactobacilli (anaerobe) increased. The above, total aerobic and lactobacilli were reduced by 1 to 3 log cycles with irradiation and at the 90th day after storage the number of total lactobacilli remained $1.30{\times}10^{8}$ per ml in 3 kGy irradiated group. Irradiation treatment at 3 kGy sterilized coliforms and molds contaminating the sample as the level of $2.0{\times}10^{4}$ per ml and $5.4{\times}10^{2}$ per ml respectively and no apparent growth was observed in both control and 1 kGy irradiated groups after 20 days of storage. The population of yeast, $3.5{\times}10^{3}$ per ml initially, increased steadily during kimchi storage and at 90 days of storage the number was shown to be $5.6{\times}10^{4}$ per ml and $6.5{\times}10^{2}$ per ml in control and 3 kGy irradiated groups, respectively. 2. In the physicochemical changes during kimchi storage, pH, acidity and volatile acid of non-irradiated control at the 45th day after storage were 4.0, 0.7% and 0.066%, while those of 3 kGy irradiated group were 4.2, 0.59 and 0.06% at the 90th day of storage, respectively. The reducing sugar content of all stored samples changed inversely total acidity content, indicating irradiation delayed the changes of them. The amount of ascorbic acid decreased gradually with the storage time and irradiation dose increase. Textural parameters of 3 kGy irradiated group were superior to those of other groups at the latter stage of storage. 3. Sensory evaluations showed that 3 kGy irradiation was the optimum dose level to extend the shelf-life of kimchi more than two months as compared to control.

• Korean Journal of Microbiology
• /
• v.50 no.4
• /
• pp.296-301
• /
• 2014

Rotavirus is a major cause of acute gastroenteritis in young children in developed and developing countries. The use of probiotics for the treatment of gastrointestinal diseases is both safe and easily accessible. In this study, we evaluated the anti-rotaviral activities of probiotic mixtures in a Sprague-Dawley rat. 24 litters with their dams were randomly assigned to four groups; placebo, phosphate buffered saline (PBS), and two probiotic mixture (PRO-1 and PRO-2) groups. All rats were inoculated with rotavirus at dose of 8 log plaque forming units per rat at 5 days old. Animals in the PRO-1 and PRO-2 groups were orally administered probiotic mixtures 1 or 2, respectively, at a dose of 8 log colony forming units daily during 4 days. For control purposes, placebo and PBS groups were orally administered the same amount of placebo (containing maltose and polydextrose) or PBS once daily for 4 days, respectively. Antiviral analysis was performed by real-time quantitative PCR (RT-qPCR) and observing intestinal villi. As a result, weights of small intestines were greater in the PRO-1, PRO-2 groups than in control groups. Villi were short and villous epithelial necrosis was exhibited in control groups, but these morphological changes were not observed in PRO-1, PRO-2 treated rats. RT-qPCR analysis showed that VP7 gene level of rotavirus in fecal samples and small intestinal epithelial cells were lower in the PRO-1 and PRO-2 groups. These findings suggest that probiotic mixtures may be useful probiotics for the treatment of or as alternative therapies for rotaviral gastroenteritis.

• Journal of Food Hygiene and Safety
• /
• v.3 no.4
• /
• pp.225-232
• /
• 1988

To improve the storage method for Kimchi, optimal ripening Kimchi was irradiated with doses of 1,3,5 kGy Co-GO gamma radiation, followed by the microbiological, physicochemical and sensory evaluations during storage at $5^{\circ}C$. 1. Total aerobic count increased in the beginning of storage and then decreased slowly as the number of total lactobacilli (anaerobe) increased. The above total aerobic and lactobacilli were reduced by 1 to 3 log cycles with irradiation and at the 90th day after storage the number of total lactobacilli remained $1.30{\times}10^{8}\;per\;ml$ in3 kGy irradiated group. Irradiation treatment at 3 kGy sterilized coli forms and molds contaminating the sample as the level of $2.0{\times}10^{4}\;per\;ml\;and\;5.4{\times}10^{2}\;per\;ml$, respectively and no apparent growth was observed in both control and 1 kGy irradiated groups after 20 days of storage. The population.of yeast, $3.5{\times}10^{3}\;per\;ml$ initially, in, creased steadily during Kimchi storage and at 90 days of storage the number was shown to be $5.6{\times}10^{4}\;per\;ml\;and\;6.5{\times}10^{2}\;per\;ml$ in control and 3 kGy irradiated groups, respectively. 2. In the physicochemical changes during Kimchi storage, pH, acidity and volatile acid of non-irradiated control at the 45th day after storage were 4.0,0.7% and 0.066%, while those of 3 kGy irradiated group were 4.2, 0.59 and 0.06% at the 90th day of storage, respectively. The reducing sugar content of all stored samples changed inversely total acidity content, indicating irradiation delayed the changes of them. The amount of aseorbic acid decreased gradually with the storage time and irradiation dose increase. Textural parameters of 3 kGy irradiated group were superior to those of other groups at the latter stage of storage. 3. Sensory evaluations showed that 3 kGy irradiation was the optimum dose level to extend tite shelf-life of Kimchi more than two months as compared to control.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.13 no.3
• /
• pp.319-325
• /
• 1984

This experiment aims to observe the nutritive value of blood sausages by manufacturing three kinds of them in order to utilize various by-products of swine when it is processed. In attempt to do so, five different diets were made: one control diet and four diets in which three kinds of blood sausages(blood sausage-1 was made with sausage meat 10%, fat 40%, blood 20%, skin 20% and liver 2%. blood sausage-2 was made with ham meat 30%, fat 20%, blood 20%, liver 2% and skin 20%. blood sausage-3 was made with smoked ham patch 30%, fat 20%, blood 20%, liver 2% and skin 20%) and mixed sausage(sausage meat 20%, fat 10% and fish meat 35%) were mixed with control diet at the rates of 10% respectively. These diets were fed to growing male and female albino rats for 6 weeks. The results obtained through this study are summarized as follows. In body weight gain of male rats, blood sausage-1 and 2 groups were significantly higher than mixed sausage group during the experimental period, and in that of female rats, control group and blood sausage-1 group were similar, but the other groups were lower than control group. Food intake was different in each group every week, but the amount of that was similar to each one throughout all experimental period. Food efficiency ratio and protein efficiency ratio in male were similar in each group, but slightly different in female during the feeding period. Liver weights of male in mixed sausage group and blood sausage-3 group were lower than those in control group and blood sausage-2 group, but liver weight of female in blood sausage-2 group was lower than that in control group. And all groups were similar in liver weight per 100 g of body weight. Mixed sausage group and blood sausage-1 group were lower than control group in kidney weight of male, and blood sausage-1 group was lower than control group in kidney weight of female. Kidney weight per 100 g of body weight of male showed that blood sausage-1 group was lower than the other groups. Spleen weight was similar in all groups. Hematocrit and hemoglobin contents in blood, total protein, albumin, albumin/globulin ratio, total lipid and total cholesterol contents in serum were showed almost similar in all groups.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.4
• /
• pp.610-613
• /
• 2012

Oyster shell has a high content of $CaCO_3$ to be used as a acidic soil amendment. To enhance productivity of barley and soil microbe in an upland soil, oyster shell and calcium-magnesium carbonate were selected as a soil amendments in this study. A field experiment was treated no treatment (hereafter, control), oyster shell lime $3.09Mg\;ha^{-1}$ and $2.38Mg\;ha^{-1}$, and calcium-magnesium carbonate $2.38Mg\;ha^{-1}$ as amount of lime requirement in silt loam soil. The yield of barley from the oyster shell lime treatment was the highest. The protein content of barley was the highest of 11.1% in the calcium-magnesium carbonate, followed by 10.7% for the control, 10.6% for the oyster shell lime $3.09Mg\;ha^{-1}$, and 10.4% for the oyster shell lime $2.38Mg\;ha^{-1}$. Soil pH value was higher than that of control in harvesting stage. In addition, the population of soil bacteria was highest in oyster shell lime $2.38Mg\;ha^{-1}$, actinomycetes was highest in calcium-magnesium $2.38Mg\;ha^{-1}$. We concluded that the oyster shell lime can be effective to restore soil nutrient and microbe balance in an upland soil.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.35 no.3
• /
• pp.418-426
• /
• 2008

The objectives of this study were to examine the properties of fluoride-releasing resin composite restorative materials. Four commercially available compomer materials (Compoglass F: CF, $Dyract^{(R)}$ AP: DA, $Dyract^{(R)}$ flow: DF, F2000: FT) and one fluoride-releasing composite resin ($Tetric^{(R)}$ Ceram: TC) were selected as experimental materials. Rectangular-shaped tensile test specimens were fabricated in a teflon mold giving 5mm in gauge length and 2mm in thickness. Disk-shaped specimens were fabricated in the split teflon mold with diameter of 15mm and thickness of 1mm. After curing for an hour, specimens were immersed in deionized water at $37^{\circ}C{\pm}1^{\circ}C$ for 30 days. All specimens were thermocycled for 10,000 cycles with 15 seconds of dwelling time in each $5^{\circ}C$ and $55^{\circ}C$ water baths. Toothbrush abrasion test was conducted under a load of 1.5 N and the abraded surfaces were examined with surface roughness tester (SV-3000, Mitutoyo Co, Japan) and SEM (JSM-5800, JEOL, Japan). Fluoride recharging was done by toothbrushing for 3 min. using a fluoride toothpaste (Perio Alpine Herb, LG Household & Health Care, Korea). The results obtained were summarized as follows; 1. The highest tensile strength value of 32.3 MPa was observed in TC group and the lowest value of 16.8 MPa was observed in CF group. The tensile strength of TC group was significantly higher than those of CF and DF groups (P<0.05). 2. The lowest Ra value of 0.287 was observed in TC group and the highest value of 1.516 was observed in FT group. The Ra value of FT group was significantly higher than other groups (P<0.05). 3. The abraded surfaces revealed the increase of surface roughness due to the protrusion and missing of filler particles. 4. The release of fluoride of compomers after tooth brushing by Perio Alpine Herb was initially large and then followed by small and continuously. But it remains small and constant in fluoride-releasing composite resin of TC. 5. The highest value of fluoride release after toothbrushing by Perio Alpine Herb was $2.064{\mu}g/cm^2$ in CF group and the lowest value was $0.1119{\mu}g/cm^2$ in TC group. The amount of fluoride release of CF group was significantly higher than other groups (P<0.05).

• Korean Journal of Plant Resources
• /
• v.25 no.2
• /
• pp.232-239
• /
• 2012

A laboratory experiment was conducted to determine the content of phenolics and flavonoids, antioxidant activity and cytotoxicity from methanol extracts of different plant parts of $T.$ $officinale$ F. H. Wigg. Total phenolics [mg chlorogenic acid equivalents (FAE) $kg^{-1}$ DW] was highest in flower extracts (72.0 mg $kg^{-1}$), followed by leaf, root, and stalk extracts of $T.$ $officinale$ ($p$ < 0.05). The result of total flavonoid level [mg naringin equivalents $kg^{-1}$ DW] had same tendency to differential total phenolics contents among plant parts, but showed lower ranges of amount. The antioxidant activity of the methanol extracts from all the plant parts dose-dependently increased. DPPH (1,1-diphenyl-2-picryl hydrazyl radical) free radical scavenging activity was highest in flower extracts ($IC_{50}$ value = 624.3 mg $kg^{-1}$ ), and followed by leaf, root, and stalk extracts of $T.$ $officinale$ ($p$ < 0.05). By means of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, cell viability of Calu-6 for human pulmonary carcinoma and SNU-601 for human gastric carcinoma showed the lowest $IC_{50}$ value in the flower extracts ($IC_{50}$ value = 85.7 and 311.4 mg $kg^{-1}$, respectively), indicating the highest cytotoxicity. The results suggested that total phenolics content and total flavonoids level in different plant parts of $T.$ $officinale$ were highly correlated with antioxidative ($r^2$=0.7280 to 0.9971) or with cytotoxic activities ($r^2$=0.5795 to 0.9515).

• Korean Journal of Poultry Science
• /
• v.40 no.3
• /
• pp.253-262
• /
• 2013

This experiment was conducted to investigate the effects of floor type and heating system on performance, housing environment and health status of ducks reared in three types of duck house (OD : Open floor house-Direct heating system, OF : Open floor house-Floor heating system and LD : Loft type house-Direct heating system). In OF treatment, PVC pipes were installed for heating under concrete floor and covered with litter. In LD treatment, plastic mesh was installed 50 cm above the floor so that duck's droppings can pass through it. Each treatment had four replicates of 25 birds (Cherry Valley duck breed) per pen. There were no significant differences in weight gain and feed intake of ducks for 6 weeks among all treatments. However, feed conversion ratio in LD was significantly higher (p<0.05) than that in OF. No differences were found in carcass charac- teristics, with the exception of abdominal fat weight where OF were higher than the others. Concentrations of $CO_2$ and $NH_3$ gas in OD were higher than those of OF and LD at 3, 4 and 5 weeks. Moisture content in litter of OF was lower than that of OD. In contrast, the amount of dust in the air was higher in OF than in OD. The amount of fuel used for 6 weeks in LD was lower about 21% than that in OD. Some of unusual symptoms were observed in open floor house and loft type house, such as lying, spraddle legged, twisted ankle and legs, wounded sole, or etc. No components of leukocyte and erythrocyte of blood were significantly different among all treatments. The results of this experiment showed that OF and LD systems had no positive effects on performance of meat type commercial duck. However, there were some positive effects of certain house type for the improvement of environmental condition in duck house for hygienic production. In the future, more research on the effect of various facilities and systems for duck house is needed.