• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.261-271
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• 2003

A condition evaluation procedure for the pavement foundations using multi-load level Falling Weight Deflectometer(FWD) deflections is presented in this paper. A dynamic finite element program incorporating a stress-dependent material model, was used to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical responses, such as stresses and strains in base and subgrade layers, have been established. FWD deflection data, Dynamic Cone Penetrometer(UP) data, and repeated load resilient modulus testing results used in developing this procedure were collected from the Long Term Pavement Performance (LTPP) and North Carolina Department of Transportation (NCDOT) database. Research effort focused on investigation of the effect of the FWD load level on the condition evaluation procedures. The results indicate that the proposed procedure can estimate the pavement foundation conditions. It is also found that structurally adjusted Base Damage Index (BDI) and Base Curvature Index (BCI) are good indicators for the prediction of stiffness characteristics of aggregate base and subgrade respectively. A FWD test with a load of 66.7 kN or less does not improve the accuracy of this procedure. Results from the study for the nonlinear behavior of a pavement foundations indicate that the deflection ratio obtained from multi-load level deflections can predict the type and quality of the pavement foundation materials.

• Korean Journal of Health Education and Promotion
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• v.14 no.1
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• pp.147-160
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• 1997

Nowadays according to the complexity of our daily life due to the development of industry and transportation various kinds of injuries happen. Since 1993 the death rate among 5-14 age children by injuries amount to about 57%. Furthermore, the injury of children can give a direct damage to their own family and it can also bring a serious loss to the country as well as the community where they live in accord with degree of an injury. From this reason, the importance of safety education has been increasing. In this study, it is aimed to clarify the effect of injury preventive behaviors on injury incidence of the 6th grade students in the elementary school. This study is accomplished by the survey sampled from 9 elementary schools in seoul, each of which belong to different district. The survey took for 15 days from the date of september 10th 1996 to september 25th 1996 and the results were as follows; 1. For demographic characteristic, sexual distribution was 48.7% of male students and 47.1% of female students. The required time from home to school was 10-19 minutes(51.8%), and the most way of their going to school is to walk(89.7%). Mothers who graduated from high school were 46.6% and 49.4% of fathers were above university graduated level. The most vocation of mothers was housewife as 56.7%. 2. The results of analysis on the injury rates, 75.8% of children experienced more than one injury and the most was play injury. With regards to sites where injuries happened, the room, the kitchen, and the living room in the house ranked first(38.3%) and then injuries at school such as on the playground, in the classroom, and on the stairs was 34.1%. 3. Considering the rate of injury incidence in accordance with demographic characteristics, male students experienced more injuries than female students(p〈0.05). For the way from home to school, children who went to school by bicycle experienced the most injuries and then on foot, by bus in order of which differences were statistically significant(p〈0.05). 4. From the comparison of parents' safety education practice and the injury incidence, the less often parents practice safety education, the more often children experience injuries(p〈0.05). 5. The results of analysis on the effect of injury preventive behaviors on accidents children who didn't act injury preventive behaviors experienced much more injuries than those who did injury preventive behaviors of which differences were statistically significant(p〈0.01). 6. From the results of analysis of factors effecting on the elementary school children's injuries, children without injury preventive behaviors had more effect on accidents than those who had injury preventive behaviors as odds ratio 2.06(p〈0.01), and the odds ratio of male students compared with female students was 1.47(p〈0.05).

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.14-21
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• 2011

A unit modular system is a construction method which installs on site by manufacturing 50%~90% of the whole process in the factory. This method can minimize the process in the site and maximize the operation, which will reduce the duration and improve the overall quality. The recent paradigm of construction is to be sustainable building. Modular system can be regarded as a sustainable building construction method because it can reduce the amount of construction waste by recycling partial or whole part of overdue building be torn down. A unit modular system is the answer to cope with the increasing market of small size housings. A unit modular system is the most appropriate option at this point. This research proposes the standard operation and construction process of modular system, which enable to optimal system. A case study of reconstructing small-size housing was introduced to support this proposal. Finished unit modular is the reasonable way. However, 80% of complication rate of the modular is the most rational when a defect occurrence during delivery is considered.

• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.489-496
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• 2016

Recently, a concern about hollow core precast concrete (PC) slab has been increased as a method to improve the construction ability by reducing the self weight of structures during the construction. Hollow core slab which is known as a typical PC slab in domestic construction of PC building has a problem to put shear reinforcements in the web of element during the production of element in the factory. With regard to this point, recently, tripple ribs slab (TRS) which can be said as a new type of half PC slab system was developed. In TRS, it is possible to place shear reinforcements in PC element during the production of the element in the factory. This paper presents the shear test result of TRS which was done by one point loading test under simple support condition. Test parameters are the presence of cast-in-place (CIP) concrete and the contribution of lattice bars. From the test, it was found that the TRS has sufficient shear capacity to resist the design load and its strength can be predicted by the code equations for general beam. It is recommended to ignore the strength of lattice bar in the calculation of shear strength during the construction since its contribution is too low to be considered when CIP is not casted.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.233-240
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• 2018

The aim of this study was to investigate the cardiometabolic risk factors (CRF) of community dwelling women based on a combination of body mass index (BMI) and waist circumference (WC). This cross-sectional study was based on 1,447 subjects between 30 and 60 years of age. Subjects were categorized into 4 groups by BMI and WC [group 1, BMI<$25kg/m^2$ and WC<85 cm; group 2, BMI<$25kg/m^2$ and WC>85 cm; group 3, BMI>$25kg/m^2$ and WC<85 cm; and group 4 (BMI>$25kg/m^2$ and WC>85 cm. Logistic regression analyses showed that subjects in group 2 had 1.75 times increased risk of clustering of 2 or more CRFs compared with subjects in group 1 (p<0.001). In conclusion, early detection of people with normal weight but high waist circumference may prevent them from getting worse by implementation of lifestyle intervention, consisting of regular exercise and healthy eating. In addition, further studies on appropriate exercise contents for them should be examined.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.113-119
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• 2018

The purpose of this study is to verify the effect of participating in teaching material development program using 3D printer on the recognition of universal design for learning of early childhood special education pre-service teachers. This study was conducted on 30 early childhood special education pre-service teachers who participated in teaching material development program using 3D printer. The results of this study showed that the early childhood special education pre-service teachers use of the 3D printer-based teaching material development program resulted in statistically significant differences in the 4 low rank factors of the universal design for learning. This research shows that direct experience in developing teaching material using 3D printers is very effective to improve universal design for learning awareness. In addition, the experience of developing teaching material for pre-service early childhood teachers is important for improving the instructional design ability, and they need the practice of the development of the teaching material using the latest technology for teaching students with various needs.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.37-43
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• 2013

Recently, experimental and analytical researches have been performed in order to find interface failure between FRP plate and concrete in near surface-mounted (NSM) retrofit using FRP plate. As a result, it was found that the bond strength between concrete and NSM FRP plate had a close relationship with shape of FRP, concrete compressive strength and bond length. However, research need is increasing about another factors such as suitable space of FRP plate and group effect. In this study, therefore, a bond test was performed with aforementioned factors and compared with a previous equation to verify its suitability for predicting bond strength of NSM FRP plate. From the test, it was found that the bond strength increased according to the increase of space of NSM FRP plates even if its bond length was same. The splitting failure of concrete governed when space of FRPs was too narrow and it changed to FRP's tensile failure with increase of the space. From the evaluation of test specimens using previous equation, it was found that the bond strength could be predicted properly with consideration of group effect.

• The Korean Journal of Ecology
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• v.22 no.3
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• pp.139-144
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• 1999

In order to clarify ecological survival strategy of Rumex crispus community dominating under contaminated area of lower region of Kumho riverside including Chimsangyo (CS), Paldalgyo (PD), Talseochon (TS) and Kumhogyo (KH), we analyzed the content of heavy metals and inorganic matter and vegetative growth. R. crispus showed rapid formation of community by high growth rate, high T/R ratio and showed maximum T/R ratio at the contaminated area Talseochon. Nitrogen and phosphorus contents in R. crispus showed high value in shoot than that of root. T/R ratio of nitrogen and phosphorus showed 3.1∼3.6 and 1.5∼4.5 for the early growth stage, and 6.7∼17.3 and 3.9∼8.3 for the late one, respectively. The absorbed heavy metals by riot were translocated to shoot, the heavy metal content in shoot higher than those in root of Cu, Zn, Fe, and Pb for 3.6, 1.7, 1.5 and 4.8 times, respectively. Distribution ratio of the heavy metals in each organ showed 61∼85% and 15∼39% for shoot and root, respectively. R. crispus accumulated heavy metals in the order of Fe>Zn>Cu>Pb in shoot, and showed maximum values of Cu, Zn, Fe and Pb for 89.7, 376.6, 2946.1 and 13.2 ㎍/g dw, respectively at Talseochon in April. A physiological and morphological characteristics of R. crispus showed thickened leaf, increased water content above 80% and rapid growth of shoot. R. crispus showed ecological adaptation to the contaminated area by transportation of heavy metals and inorganic matter to shoot, and by accumulation of Ca ion in root.

• Journal of the Korean earth science society
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• v.41 no.5
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• pp.447-458
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• 2020

This study presents the K-means clustering analysis-based classification of the meteorological patterns affecting the occurrence of high PM₁₀ concentration in the southeastern region of the Korean peninsula for the last five years (2014-2018). Regional differences in Busan, Ulsan, and Gyeongnam related to high PM₁₀ episodes, were clarified through the statistical comparison study using synoptic scale meteorological elements using NCEP (National Centers for Environmental Prediction/FNL (Final Operational Global Analysis) re-analysis meteorological data. Meteorological patterns were classified into a total of five categories (C1-C5). The incidence of each cluster was 24.8% (C1), 21.3% (C2), 20.4% (C3), 17.3% (C4), and 16.2% (C5), respectively. The high PM₁₀ concentration in the southeastern region resulted from long and short range transports (C1, C3, C5) from outside of the region, and the emissions (C2, C4) inside the region. In the high PM₁₀ episodes in Busan, Ulsan, and Gyeongnam regions, meteorological characteristics such as different geopotential height and wind speed at 500 hPa in each cluster and the change in the location of high pressure over Korean Peninsula is strongly associated with the dispersion of PM₁₀ around inventories in the region and the tendency of long-range transportation of PM₁₀ emitted from outside of region.

• Journal of Environmental Science International
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• v.29 no.10
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• pp.989-996
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• 2020

This study was conducted to determine the effect of low temperature and low radiation conditions on the yield and quality of hot pepper at an early growth stage in Korea. In plastic greenhouses, low temperature, low temperature with covered shading treatments were set 17 to 42 days after transplanting. The pepper growing degree days decreased by 5.5% due to the low temperature during the treatment period. Radiation decreased by 74.7% due to the covered shading. After commencing treatments, pepper plant growth decreased with low temperature and low radiation. Analysis of the yield showed that the first harvest was delayed by low radiation. The cumulative yields of 119 days after transplanting were 1,956, 2,171, and 2,018 g/㎡ for control, low temperature, and low temperature with low radiation respectively. Capsaicin and dihydrocapsaicin concentrations in pepper fruit decreased with low temperature and low radiation. To investigate the photosynthetic characteristics according to the treatment, the carbon dioxide reaction curve was analyzed using the biochemical model of photosynthesis. Results showed that the maximum photosynthetic rate, V_cmax (maximum carboxylation rate), J (electric transportation rate), and TPU (triose phosphate utilization) decreased at low temperatures; the maximum photosynthetic rate, J, and g_m (dark respiration rate) were reduced by shading. These results indicate that low temperature and low radiation can retard early growth, yield, and quality, but these can also be recovered 119 days after planting. Based on the results, the yield and quality of pepper can recover from abiotic stresses with proper cultivation.