• Journal of dental hygiene science
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• v.11 no.6
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• pp.521-526
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• 2011

The purpose of this study was to evaluate the long term effect of school-based oral health program on decrease of dental caries among elementary school children. The subjects of this study were total 727 students of one elementary school in Deagu, Korea. They had received school-based oral health programs for more than one year since 2004. This school-based oral health program included regular oral examination, fluoride mouth-rinsing, pit-and-fissure sealing, APF gel application, tooth brushing instruction and take the xylitol tablet after lunch during school days. The subjects' oral health status were examined by two calibrated dentists every year from 2004 to 2009. The DMFS index of $1^{st}$ grade to $6^{th}$ grade experimental and control group was 0.07, 0.39, 0.55, 0.67, 0.81, 1.79 and 0.31, 0.86, 1.07, 1.04, 2.71, 3.08 respectively. It's significantly different in $5^{th}$ grade(p<0.001) and $6^{th}$ grade(p=0.018) when it compare with control group. This study partially showed effect of school-based oral health programs on decrements of dental caries. This program should be expanded widely among elementary school in Korea. Xylitol tablet also recommended to included in school-based oral health programs.

• Journal of dental hygiene science
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• v.11 no.6
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• pp.505-512
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• 2011

The purpose of this study was to examine the oral health behavior and awareness of teachers in community children's centers, the state of oral health care among children in the centers and the opinions of the teachers on child oral health education in a bid to gather information required for the development of oral health education programs geared toward community children's center teachers. The subjects in this study were 178 teachers who worked in 98 community children's centers in the city of Incheon. After a survey was conducted from April 28 to June 4, 2010, the collected data were analyzed. The findings of the study were as follows: The 57.3% of the teachers investigated provided toothbrushing guidance from time to time or couldn't do it at all. As for the reason why toothbrushing guidance was scarcely conducted, the largest group cited shortage of sinks(27.5%) as the reason, and the second biggest group replied they couldn't afford to pay attention to that due to heavy workload(20.6%). The third greatest group was pressed for time(16.7%). The teachers got a mean of 3.27 in oral health behavior, and 87.7% were concerned about children's oral health. The group of teachers who ever received oral health education was significantly better at oral health behavior and showed significant more interest in oral health(p<0.01). The 97.2% of the respondents considered oral health important. Concerning the reason, they replied it was crucial for systemic health (74.2%). The 89.4% of the teachers viewed child oral health education as necessary, and 86.5% had an intention to provide oral health education for children. They hoped to receive education on the oral health control act(4.52) and the prevention of dental caries(4.40). The above-mentioned findings confirmed that in order to step up the oral health promotion of child users of local children's centers, it's necessary to provide secondhand education for them through their teachers who have a great impact on them. Therefore the development of oral health education programs that cater to local children's center teachers is required.

• Korean Journal of Environment and Ecology
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• v.31 no.2
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• pp.202-219
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• 2017

The purpose of this study was to analyze the community structure of forest vegetation in Mt. Geumsusan belong to Woraksan National Park for providing basic information of ecological management. Data were collected by 41 plots from June to November in 2016 using Z-M phytosociology method, which was analyzed with vegetation types, mean importance value and coincidence method. As the results, the forest vegetation was classified into Quercus mongolica community group including Cornus controversa community, Castanea crenata community(Vegetation unit 3), Quercus variabilis community(Vegetation unit 4) and Q. mongolica community(Vegetation unit 5). C. controversa community was divided into two groups such as Ulmus davidiana var. japonica group(Vegetation unit 1) and Parthenocissus tricuspidata group(Vegetation unit 2). Mean importance percentage of vegetation unit 1 was showing Fraxinus rhynchophylla 14.9%, Morus bombycis 8.7% and Acer pictum subsp. mono 8.3%, that of unit 2 was Larix kaempferi 23.2%, C. controversa 20.1% and P. tricuspidata 6.5%, that of unit 3 was Q. mongolica 15.8%, C. crenata 13.4% and F. rhynchophylla 9.8%, that of unit 4 was Q. mongolica 26.6%, Q. variabilis 20.8% and Pinus densiflora 16.7%, that of unit 5 was Q. mongolica 48.3%, Styrax obassia 7.5%, F. rhynchophylla 5.3% in the order, respectively. Each vegetation unit was classified with dependance on environmental factors as 700m of altitude, $20^{\circ}$ of slope degree, middle slope of topography, 20% of bare rock, 30 taxa of present species, 80% of tree layer coverage rate and 20m of tree layer height. In conclusion, it was preferentially considered that development of peculiar and specific management methods with vegetation unit classified above should be needed for ecological and sustainable forest vegetation management.

• Journal of Bio-Environment Control
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• v.24 no.2
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• pp.100-105
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• 2015

The calculation method of infiltration loss in greenhouse has different ideas in each design standard, so there is a big difference in each method according to the size of greenhouses, it is necessary to establish a more accurate method that can be applied to the domestic. In order to provide basic data for the formulation of the calculation method of greenhouse heating load, we measured the infiltration rates using the tracer gas method in plastic greenhouses equipped with various thermal curtains. And then the calculation methods of infiltration loss in greenhouses were reviewed. Infiltration rates of the multi-span and single-span greenhouses were measured in the range of $0.042{\sim}0.245h^{-1}$ and $0.056{\sim}0.336h^{-1}$ respectively, single-span greenhouses appeared to be slightly larger. Infiltration rate of the greenhouse has been shown to significantly decrease depending on the number of thermal curtain layers without separation of single-span and multi-span. As the temperature differences between indoor and outdoor increase, the infiltration rates tended to increase. In the range of low wind speed during the experiments, changes of infiltration rate according to the outdoor wind speed could not find a consistent trend. Infiltration rates for the greenhouse heating design need to present the values at the appropriate temperature difference between indoor and outdoor. The change in the infiltration rate according to the wind speed does not need to be considered because the maximum heating load is calculated at a low wind speed range. However the correction factors to increase slightly the maximum heating load including the overall heat transfer coefficient should be applied at the strong wind regions. After reviewing the calculation method of infiltration loss, a method of using the infiltration heat transfer coefficient and the greenhouse covering area was found to have a problem, a method of using the infiltration rate and the greenhouse volume was determined to be reasonable.

• Journal of Bio-Environment Control
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• v.27 no.3
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• pp.199-205
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• 2018

The aim of this study was to confirm that effects of supplemental LED illumination on a strawberry yield and fruit quality when strawberry grown on a bottom bed to be deficient ambient light due to shading of a upper bed during cultivation by a two-bed bench system. A strawberry was cultivated as a drip irrigation system in the two-bed bench system filled with a strawberry exclusive media from October 2015 to January 2016. The upper and the bottom bed without LED illumination for growth of a strawberry were using as a control. For LED light treatments, from 10 am to 4 pm, we illuminated LEDs as $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ of light intensity by using blue, red, and mixing LED (blue plus red) on the strawberry plants of the bottom bed. In the yield of strawberry fruit, the strawberry grown on the bottom bed treated with the blue LED significantly increased compared with that of the bottom bed part control, and increased to by near 90% of the strawberry output of the upper bed part control. The soluble sugar content of strawberry fruit grown on the upper bed part control and on the bottom bed illuminated with blue or mixed LED was higher than that of red LED and the control of the bottom bed. The content of anthocyanin was the highest increased in the strawberry grown on the upper bed part control that received a lot of ambient light, however when comparing only the bottom bed, strawberry fruits grown on all LED treatments were higher than that of the control. Therefore, we considered that using of the blue LED light on the bottom bed of two-bed bench system during strawberry cultivation is advantageous for the increase of yield and improvement of fruit quality.

• Journal of Bio-Environment Control
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• v.27 no.3
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• pp.191-198
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• 2018

The objective of this study was to determine the effects of combination of air temperature and soil water contents on growth, physiological disorder rate, and yield of garlic. This experiments has been carried out in the typical plastic house (one side open and other side installed ventilation fans) which was maintained gradient air temperature (maximum different value of air temperature : $6^{\circ}C$). The excessive irrigation (EI) set at $0.34m^3/m^3$ soil moisture contents. The significant differences found in the growth parameters of garlics as affected by air temperature and soil moisture conditions. The plant height of garlic with combination of ambient $(A)+6^{\circ}C$ and optimal irrigation (OI; set at $0.22m^3/m^3$ soil moisture contents) treatments represented 47.4 cm/plant, which was the highest among all the tested treatments. The leaf length and width showed the greatest, which were 16.1 and 2.4 cm/plant, respectively, in $A+6^{\circ}C-OI$. The physiological disorder ratio was higher as 12.9% at $A+6^{\circ}C-OI$ and was not occurred at ambient temperature with EI compared with OI treatment. The bulb and clove weight were dramatically decreased at $A+6^{\circ}C$ temperature treatment. The yields were decreased by 51% in OI at $A+6^{\circ}C$ and $A+3^{\circ}C$ temperature treatment. Those results indicated that yields were decreased and ratio of physiological disorders was increased by high temperature treatments.

• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.332-340
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• 2018

Supplemental lighting with artificial light sources is a practical method that enables normal growth and enhances the yield and quality of fruit vegetable in greenhouses. The objective of this study was to investigate the effect of sulfur plasma lamp (SP) and high-pressure sodium lamp (HPS) as supplemental lighting sources on the growth and yield of paprika. For investigating the effectiveness of SP and HPS lamps on paprika, the effects of primary lighting on plant growth were compared in growth chambers and those of supplemental lighting were also compared in greenhouses. In the growth chamber, plant height, leaf area, stem diameter, number of leaves, fresh weight, and dry weight were measured weekly at SP and HPS from 2 weeks after transplanting. In the greenhouse, no supplemental lighting (only sunlight) was considered as the control. The supplemental lights were turned on when outside radiation became below $100W{\cdot}m^{-2}$ from 07:00 to 21:00. From 3 weeks after supplemental lighting, the growth was measured weekly, while the number and weight of paprika fruits measured every two weeks. In the growth chamber, the growth of paprika at SP was better than at HPS due to the higher photosynthetic rate. In the greenhouse, the yield was higher under sunlight with either HPS or SP than sunlight only (control). No significant differences were observed in plant height, number of node, leaf length, and fresh and dry weights between SP and HPS. However, at harvest, the number of fruits rather than the weight of fruits were higher at SP due to the enhancement of fruiting numbers and photosynthesis. SP showed a light spectrum similar to sunlight, but higher PAR and photon flux sum of red and far-red wavelengths than HPS, which increased the photosynthesis and yield of paprika.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.161-170
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• 2020

There is systematic spatial variations in environmental properties due to sensitive reaction to external conditions at plastic greenhouse occupied 99.2% of domestic agricultural facilities. In order to construct 3 dimensional distribution of temperature, relative humidity, CO₂ and illuminance, measurement matrix as 3 by 3 by 5 in direction of width, height and length, respectively, dividing indoor space of greenhouse was designed and tested at experimental site. Linear regression analysis was conducted to evaluate optimal estimation method in terms with horizontal and vertical variations. Even though sole measurement point for temperature and relative humidity could be feasible to assess indoor condition, multiple measurement matrix is inevitably required to improve spatial precision at certain time domain such as period of sunrise and sunset. In case with CO₂, multiple measurement matrix could not successfully improve the spatial predictability during a whole experimental period. In case with illuminance, prediction performance was getting smaller after a time period of sunrise due to systematic interference such as indoor structure. Thus, multiple sensing methodology was proposed in direction of length at higher height than growing bed, which could compensate estimation error in spatial domain. Appropriate measurement matrix could be constructed considering the transition of stability in indoor environmental properties due to external variations. As a result, optimal measurement matrix should be carefully designed considering flexibility of construction relevant with the type of property, indoor structure, the purpose of crop and the period of growth. For an instance, partial cooling and heating system to save a consumption of energy supplement could be successfully accomplished by the deployment of multiple measurement matrix.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.1059-1075
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• 2017

The objective of this study was to evaluate the freezing and thawing resistance of the existing drainage system for leakage treatment of underground concrete structures operating in cold regions. The freezing and thawing test was conducted on 4 types of drainage system specimens to evaluate the freezing and thawing resistance of the drainage system. The freezing and thawing resistance was evaluated on 4 types of Hotty-gel, as a waterproofing material, connection methods and on two methods to fix the drainage board with Hotty-gel on the surface of cement concrete specimen. One cycle of the freeze-thaw testing was 48 hours (24 hours of freezing and 24 hours of thawing), and the temperatures of freezing and thawing were at $-18^{\circ}C$ and $10^{\circ}C$, respectively. Among the 4 types of Hotty-gel connection methods, leakage occurred after 28 cycles (8 weeks) of freeze-thawing only in the Hotty-gel connection method with the 'V' groove applied to the corner of the drainage board. No leakage occurred in the 3 types of Hotty-gel connection methods. In two fixing methods, leakage occurred in the method of fixing the drainage board on the cement concrete specimen using the washer, screw and plastic wall plug. Leakage occurred at one point after 10 cycles (3 weeks) of freezing and thawing. After 28 cycles (8 weeks) of freezing and thawing, leakage point increased to 5 points. As time passed, the leak point was not increased, but the amount of leakage was increased at each leak point. The Hotty-gel connection method with cross-sectional diagonal shape was evaluated to be the highest in the production efficiency considering the production time and manufacturing method of the Hotty-gel connection shape. In the construction efficiency considering the construction time and construction method, the fixing method of air nailer, fixed nail and washer was superior to that of the washer, screw and plastic wall plug.

• Progress in Medical Physics
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• v.24 no.4
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• pp.243-252
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• 2013

The aim of this study was to clarify the impacts of acquisition parameters on artifacts in four-dimensional computed tomography (4D CT) images, such as the partial volume effect (PVE), partial projection effect (PPE), and mis-matching of initial motion phases between adjacent beds (MMimph) in cine mode scanning. A thoracic phantom and two cylindrical phantoms (2 cm diameter and heights of 0.5 cm for No.1 and 10 cm for No.2) were scanned using 4D CT. For the thoracic phantom, acquisition was started automatically in the first scan with 5 sec and 8 sec of gantry rotation, thereby allowing a different phase at the initial projection of each bed. In the second scan, the initial projection at each bed was manually synchronized with the inhalation phase to minimize the MMimph. The third scan was intentionally un-synchronized with the inhalation phase. In the cylindrical phantom scan, one bed (2 cm) and three beds (6 cm) were used for 2 and 6 sec motion periods. Measured target volume to true volume ratios (MsTrueV) were computed. The relationships among MMimph, MsTrueV, and velocity were investigated. In the thoracic phantom, shorter gantry rotation provided more precise volume and was highly correlated with velocity when MMimph was minimal. MMimph reduced the correlation. For moving cylinder No. 1, MsTrueV was correlated with velocity, but the larger MMimph for 2 sec of motion removed the correlation. The volume of No. 2 was similar to the static volume due to the small PVE, PPE, and MMimph. Smaller target velocity and faster gantry rotation resulted in a more accurate volume description. The MMimph was the main parameter weakening the correlation between MsTrueV and velocity. Without reducing the MMimph, controlling target velocity and gantry rotation will not guarantee accurate image presentation given current 4D CT technology.