• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.303-308
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• 2016

To investigate the effect of calcium chloride ($CaCl_2$) using for deicing salts in winter on gas exchange and stomatal responses of 3-year-old Prunus serrulata, we treated twice (1 L) $CaCl_2$ solution (0.5%, 1.0% and 3.0%) in the root zone before leaf unfolding. Stomatal conductance ($g_s$), photosynthetic rate ($P_n$), transpiration rate ($T_r$) and water use efficiency (WUE) in the leaves of P. serrulata were decreased with increasing of $CaCl_2$ concentration. Even though stomatal conductance and photosynthetic rate were reduced by $CaCl_2$, intercellular $CO_2$ concentration ($C_i$) in $CaCl_2$ treatments has similar or higher values compared with control. These results suggest that non-stomatal limitation as well as stomatal limitation induced the reduction of photosynthetic rate together. On the other hands, treatment of $CaCl_2$ before leaf unfolding also affected leaf morphology traits. We proposed that reductions of stomatal length and leaf size and high pore density with increasing salinity is adaptative mechanism to reduce the water loss in plant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1138-1146
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• 2012

The purpose of this study is to identify the relevance of drinking habits among college students on the creation of drinking problems and behavioral problems and depression related to drinking problems. For this, random sampling was performed on students enrolled in a college located in Chungcheongnam-do from December 12, 2011 to December 23, 2011. For the study instruments, we gathered data using questionnaires in with a survey reorganized based on literary reviews and previous studies. A total of 262 questionnaires have been collected. The results of the investigation are as follows. As a result of performing the frequency analysis to find the drinking habits of college students, 38.2% of them were found as having drinking habits. Also as a result of analyzing whether there is difference of depression levels according to the drinking habits of college students, the instance of having drinking habits had relatively high depression level compared to the instance of not having drinking habits after analyzing by the existence of drinking habit. This study found the relevance of drinking habits among college students which leads to drinking problems and depression to present the objectives for the improvement of drinking habits. Through this study, a policy oriented support of the government related to the specific drinking problem preventing strategies and programs are anticipated.

• Water for future
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• v.29 no.5
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• pp.185-202
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• 1996

The newly-developed method for estimating the instream flow, proposed by the authors (1996), was applied to the main channel reach of the Kum River basin in Korea. Performance of the suggested method was tested through the evaluations of the required flow, instream flow, and river-management flow which were estimated at five main reaches with each representative station. The mean drought flow was used as the object flow to evaluate the minimum instream flow for the mid- and large-size rivers. Water quality prediction by using the QUAL2E model was made for both cases that the planned wastewater treatment facilities may and may not be constructed. The required flow for the fish habitat was evaluated for 9 representative fish species. The instream flows required for the riverine aesthetics at Kong-ju and Puyo scenary points, for river navigation at natural channel conditions, and for current and potential recreation activities were evaluated, respectively. The instream flows required for other items are not quantified. On the whole, it is shown that the instream flow to maintain the natural riverine functions such as fish habitat, and riverine aesthetics govern the upstream reaches of the Kum River, and the artificial riverine functions such as conservation of water quality, navigation and recreations govern the middle and downstream reaches. Especially, it is found that the instream flow requirement depends largely upon the construction of wastewater treatment facilities at the Kum River basin.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.651-657
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• 2007

Odontomas are the common type of odontogenic tumors and generally are asymptomatic and frequently lead to impaction or delayed eruption of permanent teeth. They are composed of enamel, dentin, cementum and pulp tissue and are divided into compound and complex according to the morphology of the hard tissues. Compound odontomas consist of varying numbers of small toothlike structure and have a predilection for the maxillary anterior regions. Complex odontomas consist of an unorganized mass of odontogenic tissues and comprise approximately 25 percent of all odontomas and have a predilection for the mandibular posterior regions. The etiology of odontomas is uncertain but hypothesized to involve local trauma, infection and genetic factors. Treatment of odontoma is conservative surgical removal and are little probability of recurrence. These two cases were about the patients with delayed eruption of mandibular first molar and mandibular lateral incisor. We surgically removed odontoma, exposed impacted tooth and guided impacted tooth into normal position by orthodontic traction. At the completion of traction, the mandibular first molar and mandibular lateral incisor was positioned fairly within the arch and complications such as root resorption were not observed.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.1
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• pp.1-14
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• 2017

A land cover map provides basic information to help understand the current state of a region, but its utilization in the ecological research field has deteriorated due to limited temporal and spatial resolutions. The purpose of this study was to investigate the possibility of using a land cover map with data based on high resolution images acquired by UAV. Using the UAV, 10.5 cm orthoimages were obtained from the $2.5km^2$ study area, and land cover maps were obtained from object-based and pixel-based classification for comparison and analysis. From accuracy verification, classification accuracy was shown to be high, with a Kappa of 0.77 for the pixel-based classification and a Kappa of 0.82 for the object-based classification. The overall area ratios were similar, and good classification results were found in grasslands and wetlands. The optimal image segmentation weights for object-based classification were Scale=150, Shape=0.5, Compactness=0.5, and Color=1. Scale was the most influential factor in the weight selection process. Compared with the pixel-based classification, the object-based classification provides results that are easy to read because there is a clear boundary between objects. Compared with the land cover map from the Ministry of Environment (subdivision), it was effective for natural areas (forests, grasslands, wetlands, etc.) but not developed areas (roads, buildings, etc.). The application of an object-based classification method for land cover using UAV images can contribute to the field of ecological research with its advantages of rapidly updated data, good accuracy, and economical efficiency.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.3
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• pp.1-8
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• 2017

The present study aimed to investigate the effect of calcium chloride($CaCl_2$) on the growth and physiological responses of Pinus strobus and the variables that are sensitive to $CaCl_2$. Thus, changes in the visible damage, growth of root collar diameter, plant water content, chlorophyll content and composition, maximum PS II photochemical efficiency, and electron transport rate of P. strobus was analyzed in relation to treatment witih $CaCl_2$. A $CaCl_2$ solution(0.5, 1.0 and 3.0%) was applied in the root zone before leaf unfolding. Leaf browning, defoliation, and drying were observed with $CaCl_2$ application and this pattern was aggravated as the $CaCl_2$ concentration increased and the treatment period became longer. The decrease of growth in root collar diameter and height and leaf water content were observed at $CaCl_2$ 1.0% and 3.0%. The total chlorophyll content indicated that photopigment, PS II photochemical efficiency and electron transport rate significantly decreased at $CaCl_2$ 3.0%. In conclusion, $CaCl_2$ affected leaf water content and led to a decrease of capability in light harvesting and photochemical responses. Also, as a result of the correlation between calcium chloride concentration and growth and physiological response parameters, it was found that the leaf moisture content and the ratio of chlorophyll a and b reflect the damage level of calcium chloride sensitively because their coefficient of determinations were relatively high.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.412-419
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• 2009

The purpose of this study was to provide the reference data evaluating the treatment effect of orthopedic appliances. The skeletal and dental growth increments were measured in 24 normal mixed dentition children (boys: 14, girls: 10) by three serial lateral cephalograms: initial mean age: 9${\pm}$1.3 years, mean observation period: 13${\pm}$1.3 months. Cephalometric changes were analysed. The results were as follows: 1. In boys, the maxilla showed forward and downward growth pattern and the mandible showed forward growth pattern (p<0.05). In girls, the maxilla and mandible showed forward and downward growth pattern(p<0.05). 2. Horizontal growth of both maxilla and mandible in girls was superior to those in boys (A point; girls: 2.39mm, boys: 1.26mm, with p<0.05), whereas vertical growth of both maxilla and mandible in boys was similar to those in girls. 3. The change in tooth axis showed labioversion of upper incisor (p<0.01) and comparatively stable lower incisor position.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.3
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• pp.195-205
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• 2020

This study addresses analysis on reactions which are induced in restraint system for airframe full-scale static structural test. This system restraints 6 degrees of freedom of a test article. It is valuable to study evaluating test error through analysis on the reactions which include all errors in a test. It is required to calculate fistly right reactions for the evaluation. This study focuses on calculation of the right reactions. The reaction is represented by sum of nominal reaction(Rn) and testing error reactions(Rce, Rerr) and is analyzed by two steps (inital vs relative reaction) in this study. It would evaluate intrinsic error at 0%DLL and error induced from applying test load, separately. Based on analysis using test data of a full-scale static test(canard type aircraft), resultant force of Rces and Rce_rs are distributed within 82.8N while resultant force of Rerr_rs shows to increase upto max. 808N as load level increment. Such well distribution of the Rce within the small range is caused from TMF values characteristics which are well distributed within -30N~40N. Additionally, it is shown through qualitative analysis on three components(X0, Y0, Z0) of the relative reaction(Rerr_r) that the reactions must be calculated with considering deformation of test article to calculate correctly reactions. This study shows also that equations characterizing deformation of components of test article are required to calculate the correct reactions, the equations must include information which will be used to calculate movement of all loading points.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.186-194
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• 2018

The aim of this study was to examine the effects of an after-school basketball training program of 12 weeks on physical abilities (grip strength, endurance, and flexibility) and learning-related factors (cognition strength, cognition speed, concentration, and mental workload) in middle school students. Middle school students (Males, N=20) were recruited for use in this study and were randomly divided into either a basketball training group (n = 10, BT) or a non-exercise control group (n = 10, CON). Two-way repeated measures ANOVA with post-hoc testing was used for data analysis. Results found endurance and flexibility in the BT group were significantly increased, but not in the CON group. In addition, cognition strength, speed, and concentration in the BT group increased and mental workload in the BT group slightly decreased. In contrast, the CON group showed a significant increase in mental workload. Our findings show that participation in after-school physical education activities (e.g., basketball training program) positively improves physical abilities and increases brain functions for learning.

• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.30-44
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• 2005

To investigate the flora and vegetation structure of vascular plants in the littoral zone of Paldang Reservoir, from April, 2003 to April 2004, nine sampling sites were selected. Along the Paldang Reservoir, 128 taxa, consisted of 51 families and 96 genera, were identified, among them, hydrophytes were confirmed as 38 taxa, which was comprised 29.7% to total taxa, whereas hygrophytes were 44 taxa and terrestrial plants were 46 taxa. Emergent hydrophytes consists of 21 taxa, including Phragmites australis and Typha angustifolia, and next, submerged hydrophytes were 8 taxa. However, the kinds and vegetation area of submerged hydorphytes were reduced compared to previous studies. In the littoral zone of Paldang Reservoir, the aquatic vegetation was widely developed near Dumulmori, Yangsuri, and Kwangdong Bridge, downstream of Kyungancheon. The average number of hydrophyte per sampling sites were 2.7 taxa, whereas hygrophytes were 2.5, and land plants were 1.8. In addition, the hydrophytes in the littoral zone of Paldang Reservoir showed the typical vertical zonation pattern like a natural swamp. These results mean that the littoral zone of Paldang Reservoir has the typical characteristics of aquatic plant ecosystem.