• Steel and Composite Structures
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• v.18 no.2
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• pp.497-517
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• 2015

This study evaluates behavior of the Y-type perfobond rib shear connector proposed by Kim et al. (2013). In addition, an empirical shear resistance formula is developed based on push-out tests. Various types of the proposed Y-type perfobond rib shear connectors are examined to evaluate the effects of design variables such as concrete strength, number of transverse rebars, and thickness of rib. It is verified that higher concrete strength increases shear resistance but decreases ductility. Placing transverse rebars significantly increases both the shear resistance and ductility. As the thickness of the ribs increases, the shear resistance increases but the ductility decreases. The experimental results indicate that a Y-type perfobond rib shear connector has higher shear resistance and ductility than the conventional stud shear connector. The effects of the end bearing resistance, resistance by transverse rebars, concrete dowel resistance by holes, and concrete dowel resistance by Y-shape ribs on the shear resistance are estimated empirically based on the push-out test results and the additional push-out test results by Kim et al. (2013). An empirical shear resistance formula is suggested to estimate the shear resistance of a Y-type perfobond shear connector for design purposes. The newly developed shear resistance formula is in reasonable agreement with the experimental results because the average ratio of measured shear resistance to estimated shear resistance is 1.024.

• Journal of the Korean Solar Energy Society
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• v.36 no.1
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• pp.11-18
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• 2016

The local wind systems in the Pohang region were categorized into wind sectors. Still, thorough knowledge of wind resource assessment, wind environment analysis, and atmospheric environmental impact assessment was required since the region has outstanding wind resources, it is located on the path of typhoon, and it has large-scale atmospheric pollution sources. To overcome the resolution limitation of meteorological dataset and problems of categorization criteria of the preceding studies, the high-resolution wind resource map of the Korea Institute of Energy Research was used as time-series meteorological data; the 2-step method of determining the clustering coefficient through hierarchical clustering analysis and subsequently categorizing the wind sectors through non-hierarchical K-means clustering analysis was adopted. The similarity of normalized time-series wind vector was proposed as the Euclidean distance. The meteor-statistical characteristics of the mean vector wind distribution and meteorological variables of each wind sector were compared. The comparison confirmed significant differences among wind sectors according to the terrain elevation, mean wind speed, Weibull shape parameter, etc.

• Journal of Aerospace System Engineering
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• v.11 no.4
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• pp.36-43
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• 2017

Blade design optimization of QTP-UAV prop-rotor was conducted using ModelCenter(R). Performance efficiency of the blade in hover and forward flight were adopted as the multi-objective function. Required power and pitch link force applied to constraint in each flight mode and limited lower than the value of the baseline blade. Design variables of root chord length of the blade, taper ratio, twist slope, twist angle at 0.5R of the blade, anhedral angle, parabolic coefficient of a tip shape and location of airfoil were used to generate the blade planform. CAMRAD-II, the comprehensive analysis program of rotorcraft, was used for performance analysis of prop-rotor blade in design process. Performance of the optimized blade improved 1.6% of figure of merit in hover and 13.6% of propulsive efficiency in forward flight. Pitch link force also reduced approximately 30% less than that of the baseline blade.

• Korea journal of population studies
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• v.8 no.2
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• pp.93-99
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• 1985

There have been numerous studies in Korea and other countries of which the major hypotheses are identifying and dearibing the conditions under which the value of children has been formed. The present study proposes to view the formation of the value of children as a correlate of family's consumption-saving and work4eisure behavior pattern. The objectives of the proposed study are to identify the socio-economic and demographic factors determining the family's consumption-saving and work-leisure behavior pattern and to analyse the relationship between the value of children and this behavior pattern. The conceptual framwork of the analysis is that an individual family's socio-economic and demographic factors influence and shape the consumption-saving and work-leisure behaviors and these behaviors in turn influence and reflect the correlates and proximate determinants of the family'sfertility. In this paper, regression model is used to analyse the hypothesized relationship among the various variables. The regression methods used are first and second stage multiple regressions. In addition, MONOVA has been used to show the interactions. Data used are collected from the government publicactions. The major findings from this study are as follows: As the living Standard improves, n individual family's consumption of necessities and its working hours decline, while savings and leisure activities increase. The phenomena result in the fertility reduction as can be seen in the more developed conntries. Child-bearing and rearing activities are found to be the important component to determine the condumption-saving and work-leisure activies. The married women's labor participation, and the investment in education and health are also found to be the factors reducing fertility rate.

• Journal of the Korean GEO-environmental Society
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• v.20 no.8
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• pp.13-20
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• 2019

In order to ground reinforcement, the chemical grouting, the anchor, the soil nailing system, the micropile, etc. can be mentioned by the methods widely used in domestic. The above ground reinforcement methods are developed by various methods depending on the type of reinforcement, installation method, presence of prestress, grouting method, etc. However, in common, the strength of reinforcement, the friction force of grout and reinforcement and the friction force of grout and ground are the main design variables. Therefore, the optimized ground reinforcement is a material with a high tensile strength of the reinforcement itself, the friction force between the reinforcement and the grout is high, and the application of an optimal grouting method is necessary to improve the friction force between the grout and the ground. In this study, a total of 20 model tests were conducted to analyze the reinforcement effects according to the shape of the reinforcement and the grouting method. As a result of the test, As a result of the experiment, it is judged that the reinforcing effect is superior to the perforated + wing type reinforcement and post grouting method.

• Journal of Cadastre & Land InformatiX
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• v.49 no.1
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• pp.5-15
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• 2019

This study is to review methodological limitations of previous studies, propose Tobit Model as an analysis model. We model used annual rent-free as dependent variable and considering to contract characteristics and building characteristics as independent variable. We model was consisted to the three model as follow: Basic model, Time control model, Quadratic model. As a result of the analysis, existing variables revealed through previous studies such as contract period, contract area, total floor area, and building age were all statistically significant. These results were robust when considering time effects. Also, floor area and annual rent-free was quadratic relationship by inverse U shape. This result provide to methodological contribution for related research. Also, provide to more accurate information for participants in seoul office market.

• Journal of the Korea Convergence Society
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• v.10 no.9
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• pp.333-342
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• 2019

This study was attempted to identify the differences in convergence variables that affect wage workers and self-employes' quality of life. The 2013-2017 National Health Nutrition Survey data were used. This study found the factors that affected the quality of life of wage workers were age, economic status, number of family members, marital status, feeling of depression, subjective health status (F = 5.06, p <.001.). Factors that affected the quality of life of self-employed were age, frequency of lunch, frequency of drinking, strength exercise day, BMI, Subjective body shape perception, stress and subjective health status (F = 8.60, p <.001). The results of this study show that in order to develop nursing interventions to improve the quality of life for workers, their characteristics and physical and psychological factors should be taken into account.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1195-1204
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• 2021

In this paper, we present an optimal design method for wave power generators using the response surface analysis. Especially, in our method, we reduce the mechanical loss by selecting the linear generator whose linear movement can be converted to the electrical energy directly with the vertical movement of waves. Therefore, we calculate the exciting force acting on the drive device in a slow-wave condition and determine the winding process with a ratio of the slots and poles for the improvement of energy conversion efficiency. In addition, we employ the regression analysis for deriving the shape factors of the stator and the translator, which have a significant effect on the performance of a generator. We choose the best design variables through the response surface analysis, and then we study the optimization method for designing the efficient experiment using the analysis results. Finally, we show the validity of the proposed method through the simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.10
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• pp.1462-1468
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• 2022

Among the data used for the diagnosis of calf disease, feces play an important role in disease diagnosis. In the image of calf feces, the health status can be known by the shape, color, and texture. For the fecal image that can identify the health status, data of 207 normal calves and 158 calves with diarrhea were pre-processed according to fecal status and used. In this paper, images of fecal variables are detected among the collected calf data and images are trained by applying GLCM-CNN, which combines the properties of CNN and GLCM, on a dataset containing disease symptoms using convolutional network technology. There was a significant difference between CNN's 89.9% accuracy and GLCM-CNN, which showed 91.7% accuracy, and GLCM-CNN showed a high accuracy of 1.8%.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.3
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• pp.31-35
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• 2022

Recently, with the 4th industrial revolution, the demand for high-density semiconductors for large-capacity data processing is increasing. Researchers are interested in researching the reliability of surface mount technology (SMT). In this study, the effect of PCB pad design on assembly and adhesion reliability of passive component was analyzed using design of experiment (DOE). The DOE method was established using the pad length, width, and distance between pads of the PCB as variables. The assembly defect rate of the passive element after the reflow process was derived according to the misplacement direction of the chip resistor. The shear force between the passive element and the PCB was measured using shear tests. In addition, the shape of the solder according to the pad design was analyzed through cross-sectional analysis.