• Restorative Dentistry and Endodontics
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• v.46 no.4
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• pp.47.1-47.9
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• 2021

Objectives: This study aimed to use a laboratory model to evaluate the efficacy of an experimental bleaching agent. Materials and Methods: The model used human extracted molars that were treated and measured for bleaching efficacy. Teeth (n = 50) were distributed into 5 groups: Negative control (NC): immersion in water for 8 hours; Nanofibers (NFs): Experimental titanium dioxide nanofibers with stirring and light activation for 8 hours; Whitestrips (WS): Crest 3D White Glamorous White Whitestrips, 2 applications daily for 30 minutes, 14 days; 1% hydrogen peroxide (HP) standard: 1% hydrogen peroxide for 8 hours; and 30% HP standard: 30% hydrogen peroxide for 8 hours. Instrumental measurements were performed using a spectrophotometer. Results were recorded at baseline, 1-day post-bleaching, and 1-week post-bleaching. Kruskal-Wallis procedure was used to determine differences in color change. Pearson correlation was used to evaluate the relationship between visual and instrumental measurements. Tests of hypotheses were 2-sided with alpha = 0.05. Results: There was no significant difference in color parameters (L1, a1, b1, and shade guide units [SGU]) at baseline (p > 0.05). There was a significant difference among the groups for overall color change (ΔE^*ab) and change in shade guide units (ΔSGU) at 1-day and 1-week post-bleaching (p < 0.05). The higher the HP concentration, the higher the color change as expressed in ΔSGU and ΔE^*ab. The negative control exceeded the perceptibility threshold of ΔE^* = 1.2 regardless of time point. NFs showed a decrease in chroma, but were not statistically different compared to the negative control. Conclusions: The laboratory model was successful in screening an experimental bleaching agent.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1545-1552
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• 2005

Sanguisorba officinalis L. has been used as a traditional remedy for arthritis, neuralgia, diarrhea, vomiting, gastric ulcer and gastro-intestinal disorders. This study was performed to investigate the protective effects of ethylacetate fraction of Sanguisorba officinalis L. ethanol extract (SOE) on the gastric mucosal damage and gastric ulcer induced by HCI-ethanol, indomethacin, Shay-ligation method, restraint and water-immersion stress, and cysteamine in rats. The experiment animals were divided into four groups: a negative control group (CON), positive control group (cimetidine 100 mg/kg-CMT or omeprazol 100 mg/kg administrated group-OMT), SOE 200 mg/kg administrated group (SOL) and SOE 400 mg/kg administrated group (SOH), respectively. Rats were given an oral or intraduodenal administration of SOE, and all SOE treatment groups compared with the CON significantly inhibited HCI-ethanol-induced acute gastritis and indomethacin-induced gastric ulcers in dose-dependent manner, of which effects were lower in a positive control drug (CMT). The inhibition rates ($\%$) on the acute gastritis induced by HCI-ethanol and the gastric ulcers induced by indomethacin in rats, 17.66$\%$ and 48.28$\%$ in SOL, 21.71$\%$, and 51.08$\%$ in SOH, and 47.26$\%$ and 58.26$\%$ in CMT compared with CON, respectively, In pylorus ligated rats, the groups of SOE showed decreases in the volume of gastric secretion and acid output. However, no significant differences were observed in the pepsin activity between treated groups . In addition, SOH also depressed gastric ulcers induced by restraint and water-immersion stress and duodenal ulcers induced by cysteamine. These results suggest that Sanguisorba officinalis L. has remarkable antigastric ulcer effects and could be developed as a new antigastric ulcer agents.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.107-117
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• 1975

Alaska pollack caught in the Northern Pacific Ocean and frozen aboard vessel are skipped to the plant and processed into frozen fillets. In the present paper quality changes during thwaing, refreezing and storage at $-20^{\circ}C$ are discussed. Natural, running-water, vacuum and steam thawing were employed as thawing methods. And contact plate, air blast, immersion in dry ice-alcohol solution freezing and storage at $-5^{\circ}C$ were applied to refreeze the thawed fillets. As quality factors content of drip released, salt-extractable protein, VBN, DNA in the drip and pH were determined. In addition, bacteriological tests were also carried out along with the whole process. In thawing of round material, the vacuum thawing was more effective than any other method, resulting in drip, salt-extractable protein $(N\%)$, VBN and DNA as $4.4\%,\;1.82\%,\;16.21mg\%$ and $13.70\;{\mu}g/ml$, respectively. Storage at $-5^{\circ}C$ as refreezing method yielded lower in drip and DNA content but similar to or slightly higher in both salt-extractable protein and VBN, which might postulate that the quality of the frozen fillet depends not largely on the secondary freezing but on the conditions of thawing and primary freezing. It seemed that most of the bacterial flora in thawed fillet came from skin and viscera of fish, worker's hands, utensils and other processing facilities, since sanitary indicative bacteria were not detected in the frozen flesh of round Alaska pollack. Bacterial quality of fillet varied with thawing methods, vacuum thawing appeared more sanitative compared with other methods as natural, running-water, and steam thawing. Bacterial colonies isolated from the thawed fillet were composed of $73.8\%$ Gram negative rod shape, $4.9\%$ Gram positive rod shape, $18.0\%$ cocci, and $3.3\%$ yeast. Decreasing rate of coliform group of the fillet during the storage at $-20^{\circ}C$ for 30 days was more than $70\%$ and that of plate count was less than of coliform group.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.1-7
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• 2011

Methods of producing hydrogen include steam reforming, electrochemical decomposition of water, and the SI process. Among these methods, the Sulfur iodine process is one of the most promising processes for hydrogen production. The thermochemical sulfur-iodine (SI) process uses heat from a high-temperature-gas nuclear reactor to produce $H_2$ gas; this process is known for its production of clean energy as it does not emit $CO_2$ from water. But the SI-process takes place in an extremely corrosive environment for the materials. To endure SI environments, the materials for the SI environment will have to have strong corrosion resistance. This work studies the corrosion resistances of the Fe-Si, Ni-Ti and Ni Alloys, which are tested in SI-process environments. Among the SI-process environments, the conditions of boiling sulfuric acid and decomposed sulfuric acid are selected in this study. Before testing in boiling sulfuric acid environments, the specimens of Fe-4.5Si, Fe-6Si, Ni-4.5Si, Ni-Ti-Si-Nb and Ni-Ti-Si-Nb-B are previously given heat treatment at $1000^{\circ}C$ for 48 hrs. The reason for this heat treatment is that those specimens have a passive film on the surface. The specimens are immersed for 3~14 days in 98wt% boiling sulfuric acid. Corrosion rates are measured by using the weight change after immersion. The corrosion rates of the Fe-6Si and Ni-Ti-Si-Nb-B are found to decrease as the time passes. The corrosion rates of Fe-6si and Ni-Ti-Si-Nb-B are measured at 0.056 mm/yr and 0.16 mm/yr, respectively. Hastelloy-X, Alloy 617, Alloy 800H and Haynes 230 are tested in the decomposed sulfuric acid for one day. Alloy 800H was found to show the best corrosion resistance among the materials. The corrosion rate of Alloy 800H is measured at -0.35 mm/yr. In these results, the corrosion resistance of materials depends on the stability of the oxide film formed on the surface. After testing in boiling sulfuric acid and in decomposed sulfuric acid environments, the surfaces and compositions of specimens are analyzed by SEM and EDX.

• Journal of Aquaculture
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• v.9 no.4
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• pp.419-427
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• 1996

In order to obtain the basic information for seedling production of surf clam, Spisula sachalinensis, spawning induction and egg development were investigated. $NH_4OH$ addition and serotonin injection could induce the spawning in surf clam. Water temperature rising, sperm suspension immersion, UV-ray irradiated seawater and $H_2O_2$ addition less affected on induction of spawning than $NH_4OH$ and serotonin did. On the other hand, males were more sensitive to the treatments than females. The response time to initial spawning in the case of $NH_4OH$ addition was $3\~4$ hours. However in the case of serotonin injection, it was within 5 minutes. The number of eggs released by $NH_4OH$ addition were significantly more than those released by serotonin injection. The serotonin injection induced higher rates of germinal vesicle breakdown than the $NH_4OH$ addition. Fertilizing and hatching rates of the eggs also were the similar results. Eggs of surf clam were demersal isolated eggs and averaging $65.2{\pm}±1.8\;{\mu}m$ in diameter after spawning. Optimum range of water temperature for the development of egg was $15\~20^{\circ}C$, The required time for development of D-shaped larvae was 42 hours at $15^{\circ}C$ and 27 hours at $20^{\circ}C$, respectively.

• Journal of Korean society of Dental Hygiene
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• v.17 no.6
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• pp.969-981
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• 2017

Objectives: The present study aimed to evaluate the preventive effects of exposure to liquid fermented milk containing various concentrations of added calcium on dental erosion, and to investigate the optimal concentration of calcium effective in reducing dental erosion. Methods: The present study consisted of a total of 6 experimental groups: a mineral water group, a fermented milk with no added calcium (0%) group, and four fermented milk with various concentrations of added calcium (0.1%, 0.5%, 1%, and 2%) groups. Twelve specimens were immersed for 1, 3, 5 and 10 minutes in each experimental drink and the change in surface microhardness was measured. Additionally, the surface was observed using a scanning electron microscope. Results: The difference in surface microhardness before and after 10 minutes of immersion in the experimental drink was the highest in the Ca 0% group, followed by the Ca 0.1%, 0.5%, 1%, 2% group and the mineral water group, in that order. The groups with a calcium concentration of more than 0.5% showed statistically significant differences in surface microhardness compared to the Ca 0% group. In addition, when the surface morphology of enamel was observed under a scanning electron microscope, the results showed that the highest level of surface damage was observed in the Ca 0% group, followed by the Ca 0.1%, 0.5%, 1%, 2% group, in that order. Conclusions:The present study confirms that a higher calcium concentration in fermented milk is associated with a higher possibility of preventing dental erosion. The addition of 0.5% calcium, which is a relatively low concentration, did not completely prevent dental erosion, but significantly inhibited dental erosion compared to fermented milk without any added calcium. Therefore, it is suggested that consumers should be educated and provided with guidance to consider the calcium content when choosing fermented milk.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.173-180
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• 1987

Symptom development and disease severity of Phytophthora blight in the sesame plants varied depending upon age of the plants tested, inoculation method, watering method, and inoculum density in both susceptible Suweon 9 and Suweon 26 and moderately resistant B-67 and IS 103 sesame lines to Phytophthora nicotianae var. parasitica when inoculated. However, successful differentiation of the sesame lines for varietal resistance was possible using 20-day old seedling, inoculation by soil infestation, saturated soil water condition by half immersion of pots in water tank, and 200 sporangia per one ml of inoculum. Spraying or soil inoculation to 70-day old plants also was effective in differentiating the varietal resistance. By the screening method Suwon 26 showed 100％ diseased plants and symptom severity index 9.0, while B-67 showed 20% diseased plants and symptom severity index 1.7. The rating scale given was from 0 through 9. For example, the scale 0 signified no symptom development, 5 signified discoloration of basal part of stem, and 9 signified discoloration of stem more than 10 cm high above the soil surface with blighted leaves. Differentiation in symptom severity also was made by percentage of the lesion area. Results evaluated using both parameters were well corresponded in varietal reaction of sesame to Phytophthora blight.

• Journal of Food Hygiene and Safety
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• v.6 no.1
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• pp.27-40
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• 1991

;ABSTRACT-The effects of gastric ulcer induced by restraint and water-immersion stress on gastric carcinogenesis in Wistar male rats treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were examined. Rats of group 1 were 2iven stress for 8 hours before they were received MNNG (100 mg/l) in drinking water for 20 weeks. Rats of group 2 were received MNNG first for 2 weeks and then were given stress once a week from 3rd to 12th weeks, with simultaneous MNNG adminitration and followed by MNNG only until 20th weeks. Rats of group 3 were received MNNG only as a positive control and rats of group 4 were not treated with carcinogen. All groups were sacrificed in 20 weeks. Sections of the pyloric mucosa were stained by avidin-biotin peroxidase complex (ABC) immuno-histochemical method. PAPG (pepsinogen isozyme 1 altered pyloric gland), body weight change, gross lesions and histopathological changes were examined. The results obtained from these studies were summarized as follows: 1. The mean body weight gains of the rats fed with carcinogens (group 1, 2, 3) were significantly lower than that of group 4 (control group, without carcinogen. p<0.05). However, the differences of the mean body weight of rats treated with carcinogen were not significant. 2. Stress treatment (group 1 and 2) increased the appearance of the numbers of PAPG (Pepsinogen 1 Altered Pyloric Gland) induced by carcinogen significantly compared with that of group 3 (carcinogen only, p<0.01). 3. The incidence rate of mucosal hyperplasia in pylorus was significantly increased in group 2 compared with group 3 (p<0.05).0.05).

• Journal of the Korean Wood Science and Technology
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• v.27 no.3
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• pp.39-50
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• 1999

This research was carried out to investigate the development of fire-retardancy treatment technology and performance evaluation of fire-retardant treated plywoods. Radiata pine, keruing, dillenia, calophyllum and terminalia veneers were treated by normal(conventional) pressure soak(NPS) and vacuum-pressure-soak(VPS) using 20% water solution of diammonium phosphate. Then, 4.8mm thick, 3ply plywoods were fabricated with combination of fire-retardant treated, untreated or water-immersion types and several composition types of radiata pine and keruing veneers, i,e. the uniform and the mixed types in species composition, and the homogenious and the alternate layer types in veneer treatment. In composed species, the retention and the treatment effects of fire-retardant chemicals III radiata pine was still greater than those of keruing. The effect of VPS treatment was larger than that of NPS treatment, however, adhesive bonding strength and bending strength of plywoods treated by these two methods were not necessarily lowered, compared to those of untreated plywood. And also, fire endurance performance of the urea melamine resin-bonded plywood was greater than that of the phenol resin-bonded plywood. In result, the appropriate combination in veneer species and layer as well as alternate fire-retardant treatments would be more efficiently available in service.