• Corrosion Science and Technology
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• v.16 no.3
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• pp.141-150
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• 2017

Impregnating with quality silicone water repellent on the concrete surface is an effective method of protecting concrete. Quality silicone water repellent has been widely used in the engineering profession because of its desirable properties such as hydrophobicity, keeping concrete breathable and preserving the original appearance of the concrete. The companies in China that produce silicone water repellent are listed. Test methods in the specifications or standards about silicone water repellent in China are summed. The test methods relative to durability of concrete impregnated with silicone water repellent (such as resistant to chloride ion penetration, resistant to alkali, resistance to freezing and thawing and weatherability etc.) and the constructive quality (such as water absorption rate, impregnating depth and the dry velocity coefficient etc.) are compared and analyzed. The results indicate that there are differences among test methods relative to different specifications with the same index and therefore, confusion has ensued when selecting test methods. All test methods with the exception of the method of water absorption rate by using a Karsten flask are not non-destructive methods or conducted in a laboratory. Finally, further research on silicone water repellent during application is proposed.

• The Journal of the Korean dental association
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• v.21 no.12 s.175
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• pp.979-984
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• 1983

As an appraisal of Water Fluoridation Program in Chungju, fluoride content in the water of that city was examined, and 1317 K primary school children aged from 6 to 13 were surveyed on their oral hygiene status. The results were as follows: 1. Fluoride content ....................... 0.8 ppm 2. dmfrate ..................................... 81.17% DMF rate .......................................... 38.88% 3. dmf t rate/index ................................ 29.17%/2.55 dmf s rate/index ............................... 14.33%/6.27 4. DMF T rate/index ............................. 6.32%/0.92 DMF S rate/index ............................ 1.86%/1.35

• Solar Energy
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• v.4 no.2
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• pp.29-36
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• 1984

This paper reviews the current status of R&D work on selective absorber materials. For the efficient utilization of solar energy, various types of selective absorber materials are being used for solar hot water heaters. Many selective absorbers which have been proposed and designed up to data are classified according to the absorption mechanisms. Temperature-time cycle method is often recommended for the measurement of solar absorptance. In addition, conversion efficiency of the solar collector with selective surface is compared with one with black paint surface.

• The Journal of the Korean dental association
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• v.22 no.12 s.187
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• pp.1059-1066
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• 1984

As an appraisal of Water Fluoridation Program in Chungju, fluoride content in the water of that city was examined, and 1176 K primary school children aged from 6 to 13 were surveyed on their oral hygiene status. The results were as followings: 1. Fluoride content ............ 0.8 ppm 2. dmf rate ............ 59.27% DMF rate ............ 39.46% 3. dmf t rate/index ............ 27.75%/2.40 dmf s rate/index ............ 11.91%/5.14 4. DMF T rate/index ............ 6.12%/0.93 DMF S rate/index ............ 1.65%/1.26

• Journal of environmental and Sanitary engineering
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• v.7 no.1
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• pp.35-44
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• 1992

This paper included the preventive measures and the prospect of lake eutrophication in korea. All pollution control techniques must be applied after the characteristics of the lakes are surveyed sufficlenty, Most of Korean lakes are the large man-made ones and their characteristics are different from those of natural ones in foreign nation. Some of many techniques for natural lakes can be applied in our lakes also, others must be revised. Lake water quality can be ameliorated only by systematic researches and technologies because lake ecosystem is very complicated. It is impossible to improve water quality with fragmentary and shortterm projects.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.759-763
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• 2005

This review presents the status of our research in liquid crystal display (LCD) photo-aligning. We present the basic mechanisms of the photo-induced order in various photo-aligning materials and in azo-dye layers in particular and show that photo-aligning methods can provide a controllable pretilt angle and anchoring energy of the liquid crystal cell, as well as its high thermo and UV stability. The photo-aligning of various types of liquid crystal displays is also discussed.

• Nutrition Research and Practice
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• v.14 no.5
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• pp.490-500
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• 2020

BACKGROUND/OBJECTIVES: A cross-sectional study was undertaken to evaluate fluid intake and hydration status in association with cognitive function among 230 adolescents (10-14 years of age) in Petaling Perdana, Selangor, Malaysia. SUBJECTS/METHODS: Urine color was used to measure hydration status, while fluid intake was assessed using the 15-item beverage intake questionnaire. Cognitive function was assessed using the Wechsler Intelligence Scale for Children, Fourth Edition. RESULTS: More than half of the adolescents were mildly or moderately dehydrated (59.6%) and only one-third (33.0%) were well hydrated. Among the daily fluid types, intakes of soft drinks (r = -0.180; P = 0.006), sweetened tea (r = -0.184; P = 0.005) and total sugar-sweetened beverages (SSBs) (r = -0.199; P = 0.002) were negatively correlated with cognitive function. In terms of hydration status, cognitive function score was significantly higher (F-ratio = 4.102; P = 0.018) among hydrated adolescents (100.38 ± 12.01) than in dehydrated (92.00 ± 13.63) counterparts. Hierarchical multiple linear regression analysis, after adjusting for socio-demographic factors, showed that soft drinks (β = -0.009; P < 0.05) and sweetened tea (β = -0.019; P < 0.05) negatively predicted cognitive function (ΔR² = 0.044). When further control for sources of fluid, hydration status (β = -2.839; P < 0.05) was shown to negatively predict cognitive function (ΔR² = 0.021). The above variables contributed 20.1% of the variance in cognitive function. CONCLUSIONS: The results highlight the links between fluid intake (soft drinks, sweetened tea, total SSBs) and hydration status with cognitive function in adolescents. Interventions aimed at decreasing the consumption of SSBs and increasing hydration status through healthy fluid choices, such as water, could improve cognitive performance in adolescents.

• Journal of the Korean Society of School Health
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• v.8 no.2
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• pp.305-314
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• 1995

A comparative study on the effects of the water fluoridation program and fluoride mouth rinsing program in the elementary school children. This study was performed to compare the oral health status of permanent teeth for children of the caries prevention effects by using methods of fluoride 309 children for water fluoridated program, 240 for fluoride mouth rinsing program and 248 for control group. The DMFS rate, DMFT index, soft and hard deposite rate were analysed from the oral examination. And 300 questionares from the parents who lived in Cheong ju city were evaluated to see the situations of using the tap water. The results were as follows; 1. Caries experience rate in permanent dentition was the lowest in fluoride mouth rinsing group. 2. It was estimated that soft deposite rate was comparatively low in the fluoride mouth rinsing group but calculus deposite rate was no significant difference in each other groups. 3. The 72.0 percentage of parents who lived in non fluoridated water area were misunderstood that they lived in water fluoridated area. 4. The 66.8 percentage of residents used the piped water as drinking water. 5. It was recommended that fluoride mouth rinsing program was suggested in rural area, on the other hands, toothbrusing program in urban area with water fluoridation to prevent the dental caries for school children.

• Nuclear Engineering and Technology
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• v.46 no.3
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• pp.373-380
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• 2014

Safety-related parameters are very important for confirming the status of a nuclear power plant. In particular, the reactor vessel water level has a direct impact on the safety fortress by confirming reactor core cooling. In this study, the reactor vessel water level under the condition of a severe accident, where the water level could not be measured, was predicted using a fuzzy neural network (FNN). The prediction model was developed using training data, and validated using independent test data. The data was generated from simulations of the optimized power reactor 1000 (OPR1000) using MAAP4 code. The informative data for training the FNN model was selected using the subtractive clustering method. The prediction performance of the reactor vessel water level was quite satisfactory, but a few large errors were occasionally observed. To check the effect of instrument errors, the prediction model was verified using data containing artificially added errors. The developed FNN model was sufficiently accurate to be used to predict the reactor vessel water level in severe accident situations where the integrity of the reactor vessel water level sensor is compromised. Furthermore, if the developed FNN model can be optimized using a variety of data, it should be possible to predict the reactor vessel water level precisely.

• Atmosphere
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• v.18 no.4
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• pp.417-427
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• 2008

In this paper, we analyzed the physical and thermodynamic characteristics of fog by using the integrated water vapor (IWV) from Global Positioning System (GPS) networks and the regular observation data of meteorological stations in GPS sites. The cases of a radiation and an advection fog were selected as samples, the conversions of water substance from the water vapor to cloud water in fog were detected by the Bulk Water-Continuity Model, and the pattern analysis is adapted on GPS IWV, temperature, wind and relative humidity. Under the specific hypothesis (saturation and stable), GPS IWV could detect quantitatively the phase changing between the water vapor and cloud water content with condensation/evaporation during the formation and dissipation of fog. After it reaches to the saturation, the relative humidity can be a limited indicator for fog. However, GPS IWV can detect the status change of fog even after the saturation. It has indicated that GPS IWV could be a new observing technique for the processes of the fog formation and the dissipation.