• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.437-445
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• 2008

The presence of a "prismless" layer on the enamel surface particularly on deciduous teeth has been reported by a number of workers. This structure, which appears to lack the normal prism delineations, could interfere with tag formation and hence, reduce bonding to such surfaces. The purpose of this study was to investigate the relationship of etching times on the effect of acid etching on primary enamel with respect to the quality of etching patterns. Labial surfaces of 32 extracted or exfoliated caries-free primary anterior teeth were used. 35% phosphoric acid gel was used only cervical regions of labial surfaces for each etching time group, 15, 30, 45 and 60 seconds. The surfaces were then washed with water for 20 seconds and dried with air spray for 20 seconds. 1. The Type 3 is 75% when the 15 seconds acid etching time was used. 2. The Type 1 is 38% and Type 2 is 75% when the 30 and 45 seconds acid etching time was used. 3. The Type 1 is 25% and Type 2 is 75% when the 60 seconds acid etching time was used. 4. An etching time of 60 seconds produced a constant and regular etching pattern. 5. There is a significant difference between the groups with respect to the patterns of etch achieved(p<0.05). 6. We confirmed that the acid induced patterns(type 1, 2) became more pronounced when the application time increased(p<0.05). $45{\sim}60$ seconds was the optimal time for etching on the primary enamel.

• Journal of Korean Society of Forest Science
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• v.105 no.2
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• pp.177-185
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• 2016

Fertilization is required to keep the balance of tissue nutrients and to produce high quality seedlings at the permanent nursery. This study was conducted to verify the optimum fertilization method for Fraxinus rhynchophylla, F. mandshurica, Pinus koraiensis, and Abies holophylla seedlings with vector diagnosis method. Seven treatments include nitrogen (N, $13.8g{\cdot}m^{-2}$), phosphorus (P, $6.1g{\cdot}m^{-2}$), potassium ($7.5g{\cdot}m^{-2}$) fertilization and 1x (N $6.9g{\cdot}m^{-2}$, P $3.05g{\cdot}m^{-2}$, K $3.65g{\cdot}m^{-2}$), 2x (twice of 1x), 4x (four times of 1x) fertilization and no fertilization. Soil pH decreased as fertilization increased. Nitrogen and NPK fertilization decreased exchangeable $Ca^{2+}$ and $Mg^{2+}$ concentrations. Height and root collar diameter of F. rhynchophylla and F. mandshurica significantly increased with N and NPK fertilization, but those of P. koraiensis and A. holophylla did not. The biomass of F. rhynchophylla and F. mandshurica was about twice higher at NPK fertilization compared to the control. The responses of vector diagnosis were different by tree species and fertilization treatment: F. rhynchophylla was in the status of N "dilution", which means the N concentration decreases with N content. Phosphorus and K were "sufficiency" state with 4x fertilization. F. mandshurica showed "retranslocation" as N content decreased without change of dry weight at N, P, K fertilization, but "dilution" state at NPK fertilization. This result suggested that optimal fertilization was required for F. rhynchophylla and F. mandshurica in seedling production stage, but was not essential for P. koraiensis and A. holophylla.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.10
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• pp.1600-1607
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• 2013

The aim of this study was to investigate effect of nutrition education methodology on consumption of processed food and personality of middle school students aged 14 to 16 years who live in Busan. We categorized questionnaire based on students' consumption of processed food and personality characteristics. Based on the above, we determined serum mineral level to validate the correlation between personal characteristics and quantifiable serum mineral level. Following adoption of a proper nutrient education methodology, we found that consumption of processed foods such as meat and meat products, frozen food, noodles, bread and snacks, and drink was significantly reduced. In addition, there were distinct changes in personality characteristics such as stability, governmentality, sociality, and responsibility that became markedly increased, whereas impulsiveness decreased. We found that these distinct nutrition- education-based changes were statistically significant, when compared before and after providing proper nutrition education. We interpret these results as group with low stability showed a high consumption of meat and meat products, noodles, bread and snacks, and drink, whereas group with high stability showed a high consumption of milk and dairy products. Similarly, we also found that group with low impulsiveness showed a high consumption of canned foods, whereas group with high impulsiveness showed a high consumption of meat and meat products, frozen food, noodles, bread and snacks. Our results indicated that serum Na after nutrition education decreased, whereas other minerals including Ca, Fe, Zn, Mg and K increased, when compared with before nutrition education procedure. This study suggests that nutrition education methodology and establishment of proper dietary educational programs keeping in view balanced dietary habits for middle school students would not only appear to make them get along with healthy dietary habits, but also change their personality characteristics.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.10
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• pp.1701-1706
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• 2013

Domestic and overseas information with regard to harmful substances are analyzed. From the results, environmental-derived hazard chemicals, which show relatively low recognition, and hazard chemicals that occur unavoidably in food manufacturing process are selected as target harmful substances. Thus, educational leaflet contents were developed based on these substances. To find the effects of education with the above contents, this study surveyed 120 female college students living in Seoul. The purpose of the survey is to analyze the change in recognition, attitude and behavior on hazard chemicals in foods. The survey found that the recognition on harmful substance in foods increased; from 31.5~78.0% before education to 98.8% after education. It also indicates that vague anxiety in which the harmful substances may damage their health decreased by approx. 25.0%; from 77.8% before education to 52.8% after education. For the question of what they would do when government promotes to reduce harmful substances in foods, 12.3% of respondents said that they would actively follow the suggestions and 73.5% of them said that they would do their best before an education. However, 56.1% of them said that they would actively follow the suggestions after the education. It indicates that the ability to recognize harmful substances changed after the education. With regard to consumer behavior, when they knew about the harmful substances in foods, 49.6% of them said that they would select foods after investigating relevant information before the education, while 77.4% of them said that after the education; which is an increase of 27.8%. Further, 45.4% of them said that they would not purchase relevant foods before the education, while 20.9% of them said that after the education; which is a decrease of 24.5%. Therefore, it is considered that vague anxiety of consumers can be eliminated by providing persuasive information on harmful substances. To expand on the communication channel with consumers for food safety, contents development and educational promotion should be enhanced for providing food safety related information.

• Journal of Genetic Medicine
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• v.6 no.2
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• pp.155-160
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• 2009

Purpose: Preeclampsia is a multisystem human pregnancy-specific disorder. The pathophysiology of preeclampsia is linked with over-stimulation of inflammatory cytokines by placental ischemia via reduced uterine perfusion pressure during pregnancy. Although an increase in tumor necrosis factor (TNF)-alpha has been reported in preeclamptic women, there is little evidence of a relationship between TNF-alpha gene variations and preeclampsia. In this study, we identified a single-nucleotide polymorphism (SNP), C-850T, in the TNF-alpha gene promoter region in Korean preeclamptic women and investigated the association between this SNP and the development of preeclampsia. Materials and Methods: This polymorphism was analyzed in peripheral blood samples from 198 preeclamptic pregnancies and 194 normotensive pregnancies using a SNapShot kit and an ABI Prism 3100 Genetic analyzer. Results: Genotypes and allele frequencies for C-850T did not differ between preeclamptic and normotensive pregnancies. The distributions of genotypes (CC, CT and TT) were 74.3%, 22.2% and 3.5%, respectively, in preeclamptic pregnancies, and 71.6%, 25.8% and 2.6%, respectively, in normotensive pregnancies. The frequencies of the C and T alleles were 0.85 and 0.15 in preeclamptic pregnancies and 0.84 and 0.16 in normotensive pregnancies, respectively. There was no increased risk of preeclampsia in subjects with the CT (OR, 0.83; P=0.44) or TT genotypes (OR, 1.32; P=0.64). Conclusion: We found no differences in the genotypes or allele frequencies of the TNF-alpha gene polymorphism between preeclamptic and normotensive pregnancies. This study suggests that the TNF-alpha gene polymorphism may be not associated with the development of preeclampsia in pregnant Korean women.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.501-510
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• 2015

In this study, we investigated the onset and release of endo-dormancy under natural conditions by observing bud break characteristics in 'Fuji' apple trees using water cuttings. Through examinations of bud break rate and days to bud break, we found that the endo-dormancy of 'Fuji' apple tree continues for 70 d from 165 to 255 d after full bloom (DAFB), from late October to early January of the following year. In addition, within 20 d of first bud break, based on a final bud break rate of 60% or more, we able to identify the timing of the changeover from para-dormancy to endo-dormancy, and endo-dormancy to eco-dormancy. Analysis of the chilling requirement during the endo-dormancy period revealed that chilling accumulation up to 255 DAFB to release endo-dormancy amounted to 666 and 517 h based on the CH and Utah models, respectively. Observation of internal changes in the bud during endo-dormancy showed that flower bud differentiation begins from mid-July, and t ime of inflorescence o f the disk f lower is a vailable to f ind. The f lower buds subsequently developed slowly but steadily during endo-dormancy and in the following year in February, the developmental stage of each organ had progressed. Moreover, the flower buds of 'Fuji' apples were mostly healthy during the dormancy period, but some exhibited necrosis of flower primordium, due partial cell damage from the formation of ice crystals rather than a direct effect of the low temperature. Flower buds were formed in both the axillary buds of bourse shoots and terminal buds of spurs, but lower bud differentiation was observed for the terminal buds of spurs at rate of about 65% of total buds, which was directly related to the bud size and shoot diameter.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.246-250
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• 2003

In order to preserve the soundness of agro-ecosystem and products safety in agriculture, this study was evaluated environmental impact in relation to the INM (Integrated Nutrient Management) and IPM (Integrated Pest Management) at paddy fields at Ok-Chun and Yang-Pyung region. By introduction of INM with the application of BB(bulk-blanded) fertilizer based on soil analysis and IPM, the application rate of fertilizer was reduced to about $28.6{\sim}39.4%$ and the yield of brown rice was increased to about $3{\sim}10%$ compared to conventional practices. The concentrations of COD, $NH_4-N$, and $NO_3-N$ in irrigation water flowed to the environmental-friendly agriculture practices were 15.0, 0.67, and 1.39 mg/L, respectively. The concentrations of COD, $NH_4-N$, and $NO_3-N$ from paddy fields in drainage water were 12.4, 0.29, and 2.42 mg/L, respectively. The total number of the freshwater invertebrates was higher in field treated with fertilization by prescription with soil testing. Also, the population density of aquatic insects was higher than the other fields at both demonstration villages. In conclusion, it was possible to reduce the amount of fertilizer and agricultural chemicals application, and increase the yield of rice by application of the environmental-friendly agriculture practices.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.103-109
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• 2016

Polyethylene pipes has useful benefits which are anti-corrosive and flexible material, so it is used to gas pipes but also class 3 water pipes of nuclear power plant, process pipes of petrochemical plant and chemical plant. So the usage of polyethylene pipes is widely increased. But it has been limited for the usage of polyethylene, because it can not be directly detected to fusion joints by using non destructive evaluation. Polyethylene pipes are connected by two methods, one is butt fusion and the other is electrofusion. Butt fusion is widely used to connecting the pipes. It is proposed to method for determining the reliability of joints in this study that is detection of the melt flow zone at fusion joints. In this study, middle density polyethylene is used, outside diameter of the test specimen is 225mm and thickness is 20.5mm. Speed of ultrasonic of this test specimen is 2,200m/s. Test specimens were fabricated by varying the heating time which means from 0% to 130% applying time through heating plate to polyethylene for detecting melt flow zone. Also 4 additional test specimens were made, one was made that not scrapping attached surface of pipes but applying 100% of the proper heating time and the others were made to include of soil, gravel and vinly tape paper at fusion joints, that were also applied 100% of proper heating time. Ultrasonic testing to measure the melt flow zone of 20 test specimens was conducted by using 3.5MHz and 5.0MHz ultrasonic probes and melt flow zone measuring was conducted to three times at different point to one specimen. To differentiate the melt flow zone signal, post image processing was equally conducted to all test results and image levels, contrast, sharpen, threshold were adopted to all teat results and the test results were displayed gray scale. From the results, for the shorter heating times the reflection area of multiple echo have been increased, so the data was obtained from the position where it can be eliminated as much as possible. At 80% of proper heating time(168 sec.), the signal of melt flow zone was obtained clearly, so measuring could be conducted. From 7% of proper heating time(15 sec.) to shorter heating times. we could not obtain the signal because test specimen was not fused. From the result, we can verify that measuring of melt flow zone by using phased array ultrasonic imaging method is possible. And we can verify to complete and incomplete butt fusion by measuring the melt flow zone.

• Korean Journal of Health Education and Promotion
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• v.13 no.1
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• pp.72-89
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• 1996

The oral health status and practices related to oral health among 44-54-year-, 55-64-year- and 65-year-old needy residents were assessed. The subjects were the residents at the Unbong Permanent Rental Apartment, Bansong-dong, Haeundae-gu. Pusan, Korea. An oral epidemiological survey was undertaken to determine the status of dental caries and periodontal health. Periodontal health were analyzed by the tool of CPITN (Community Periodontal Index of Treatment Needs). A questionnaire was used to interview for the practices of toothbrushing. The numbers of subjects were 192 for the interview on toothbrushing, 228 for the survey of dental status and 208 for the survey of periodontal status. The major results were as follows: 1. Toothbrushing frequencies per day were 1.9 among 44-54-year-, 1.7 among 55-64-year- and 1.7 among 65+-year-subjects. Percentages of after-meal-toothbrushings among total brushing frequencies per day were 73.7% among 44-54-year-, 70.6% among 55-64-year- and 76.5% among 65+-year-subjects. 2. DMFT indices were 15.5 among 44-54-year-, 16.4 among 55-64-year- and 26.6 among 65-year-subjects. Decayed teeth component of DMF teeth were 23.9% among 44-54-year-, 11.6% among 55-64-year- and 62.8% among 65+-year-subjects. Missed teeth component of DMF teeth were 55.59% among 44-54-year-, 62.8% among 55-64-year- and 77.4% among 65+-year-subjects. Filled teeth component of DMF teeth were 20.0% among 44-54-year-, 25.0% among 55-64-year- and 10.9% among 65+-year-subjects. 3. Sound permanent teeth were 16.4 among 44-54-year-, 15.6 among 55-64-year- and 5.4 among 65+-year-subjects. Present permanent teeth were 23.7 among 44-54-year-, 21.6 among 55-64-year- and 10.9 among 65-year-subjects. 4. Subjects who needed professional oral prophylaxis were 75.0% among 44-54-year-, 83.3% among 55-64-year-and 76.9% among 65-year-subjects. Subjects who needed complex periodontal treatments were 16.7% among 44-54-year-, 13.3% among 55-64-year- and 15.4% among 65+-year-subjects. 5. Sextants which needed professional oral prophylaxis were 59.3% among 44-54-year-, 71.5% among 55-64-year- and 71.5% among 65+-year-subjects. Sextants which needed complex periodontal treatments were 5.6% among 44-54-year-, 4.1% among 55-64-year- and 5.7% among 65+-year-subjects. 6. Systematic comprehensive oral health care services should be developed for old needy residents in urban area.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.511-519
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• 2008

Statement of problem: An incompatibility between the initiator systems of self-curing composite resins and light-curing adhesives was supposed recently. Purpose: The purpose of the study was to evaluate the influence of activators for self/dual bonding on dentin shear bonding strengths. Material and methods: Fifty human molars were divided into 5 groups. A flat dentin surface was created for each tooth. A self-curing composite resin (Luxacore) was bonded with the following adhesives (n = 10); One-Step, Prime&Bond NT, AdheSE, Prime&Bond NT and AdheSE were also used in combination with activators. Shear bond strengths were measured after 24 hours of water storage. The specimens were loaded in shear in the Instron until failure at a 1 mm/min crosshead speed. Data were compared using one-way ANOVA and Tukey HSD test (${\alpha}$= 0.05). Results: The dentin adhesive systems in order of decreasing median bond strength were One-Step > Prime&Bond NT with activator, AdheSE with activator > Prime&Bond NT, AdheSE. Among adhesives, One-Step had the highest bond strength. Prime&Bond NT with activator had higher bond strengths than Prime&Bond NT that was used alone, and so was AdheSE. Conclusion: Shear bond strengths were increased in Prime&Bond NT and AdheSE when these were used with activators comparing used without activators. But using activators was not effective clinically comparing One-Step.