• Atmosphere
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• v.29 no.1
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• pp.105-112
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• 2019

Measurements of vertical air motion and microphysics are essential for improving our understanding of convective clouds. In this paper, the author reviews the current research on the retrieval of vertical air motions using the cloud radar. At radar wavelengths of 3 mm (W-band radar; 94-GHz radar; cloud radar), the raindrop backscattering cross-section (${\sigma}b$) varies between successive maxima and minima as a function of the raindrop diameter (D) that are well described by Mie theory. The first Mie minimum in the backscattering cross-section occurs at D~1.68 mm, which translates to a raindrop terminal fall velocity of ${\sim}5.85m\;s^{-1}$ based on the Gunn and Kinzer relationship. Since raindrop diameters often exceed this size, the signal is captured in the radar Doppler spectrum, and thus, the location of the first Mie minimum can be used as a reference for retrieving the vertical air motion. The Mie technique is applied to radar Doppler spectra from the surface-based and airborne, upward pointing W-band radars. The contributions of aircraft motion to the vertical air motion are also described and further the first-order aircraft motion corrected equation is presented. The review also shows that the separate spectral peaks due to the cloud droplets can provide independent validation of the Mie technique retrieved vertical air motion using the cloud droplets as a tracer of vertical air motion.

• Journal of Practical Engineering Education
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• v.9 no.1
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• pp.69-75
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• 2017

In this paper, we analyzed the factors influencing the size of Korea Polytechnic as a public vocational education and training institution through analysis of demand, region, industry, and demand with established existing campus and new campus in Korea Polytechnic. By analyzing data on admission, training, and employment for 3 years out of 37 campuses, we have sampled 5 campuses by type of Korea Polytechnic, fused with the results derived from the literature analysis and in-depth analysis results, so that the regional campus will play a leading role and the direction of development. The selection of five campuses by type is a precedent study to analyze 37 campuses in the future. As a result of the study, the demand analysis through objective indicators such as the number of high school graduates, the number of employed persons, the presence of nearby industrial complexes, and policy variables is very important and reflects the reality well. Therefore, it is necessary to analyze the demand through the objective indicators in decision making related to the new campus at the pre-analysis stage. In addition to the general data proposed in this paper, that is, common variables in all regions, it is important to consider the factors that can reflect local demand characteristics when considering specific locations.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.734-746
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• 2020

Purpose: Increase in the size and number of underpasses rises occurrence of disasters such as fire and flooding inundation in underpasses. In the occurrence of disasters, the underpasses are more vulnerable to expose of crucial disasters than the general roads due to they are built underground. Therefore, The purpose of this paper is to derive system improvement items to prevent and control disasters in underpasses. Method: A hierarchical model of disaster impact factors and alternatives was developed based on prior researches and expert advices on disaster analyses and impact factors in the underpasses. The developed model was employed for surveys of pairwise comparison, and rankings of improvement were determined by applying the AHP method. Result: With a consistency of the surveys, results of relative weights of evaluation criteria(traffic accidents, fire, flooding inundation) and alternatives(law, system/planning, maintenance/human factor/environment) shows that improvement of laws and system related to the fire disaster is a top priority to prevent and control disaster of the underpasses. Conclusion: From experts' point of view, strengthening laws and systems related to disater prevention facilities such as water spray facilities, external(ground) exit in relation to fire in underpasses showed that it is an alternative to prevent disasters and minimize damage to underpasses.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.481-495
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• 2020

After the resonator on the basis of the wave-filter theory was designed to control the waves with a specific frequency range surging into the harbor, the several case with the use of resonator have been reported in some part of sea, including the port of Long Beach, USA, and yacht harbor at Rome, Italy in order to control the long-period wave motion from the vessels. Recently, the utility and applicability of the resonator has been sufficiently verified in respect of the control of tsunami approximated as the solitary wave and/or the super long-period waves. However, the case with the application of tsunami in the real sea have not been reported yet. In this research, the respective case with the use of existing resonator at the port of Mukho and Imwon located in the eastern coast of South Korea were studied by using the numerical analysis through the COMCOT model adapting the reduction rate of 1983 Central East Sea tsunami and 1993 Hokkaido Southwest off tsunami. Consequently, the effectiveness of resonator against tsunami in the real sea was confirmed through the reduction rate of maximum 40~50% at the port of Mukho, and maximum 21% at the port of Imwom, respectively. In addition, it was concluded that it is necessary to study about the various case with application of different shape, arrangement, and size of resonator in order to design the optimal resonator considering the site condition.

• Journal of the Korean GEO-environmental Society
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• v.22 no.2
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• pp.35-39
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• 2021

Photogrammetry using drone can produce high-resolution ortho image and acquire high-accuracy 3D information, which is useful. Therefore, this study attempted to determine the possibility of using drone-photogrammetry in park construction by producing a topographic map using drone-photogrammetry and analyzing the problems and accuracy generated during production. For this purpose, we created ortho image and DSM (digital surface model) using drone images and created topographic status map by vectorizing them. Accuracy was compared based on topographic status map by GPS (global positioning system) and TS (total station). The resulting of analyzing mean of the residuals at check points showed that 0.044 m in plane and 0.066 m in elevation, satisfying the tolerance range of 1/1,000 numerical maps, and result of compared lake size showed a difference of about 4.4%. On the other hand, it was difficult to obtain accurate height values for terrain in which existed vegetation when producing the topographic map, and in the case of underground buried objects, it is not possible to confirm it in the image, so direct spatial information acquisition was necessary. Therefore, it is judged that the topographic status map using drone photogrammetry can be efficiently constructed if direct spatial data acquisition is achieved for some terrain.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.496-505
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• 2020

In the previous research, the effectiveness of resonator was confirmed through the numerical analysis on two cases with the use of existing resonator at the Mukho and Imwon ports located in the eastern coast of South Korea by discussing the reduction rates of 1983 Central East Sea tsunami, and 1993 Hokkaido Southwest off tsunami, respectively. In this study, the reduction rates of tsunami height with three different resonators, Type I, II-1, and II-2, at the Samcheok port were examined respectively through the numerical analysis using COMCOT model under the same condition as the previous study. It was discussed the spatial distribution of maximum height of tsunami, change of water level, and effectiveness of resonator with the presence of new types of resonator, and change of their sizes. As a result, the effectiveness of resonator was verified through the application of new types of resonator reducing about maximum 40% of tsunami height. In order to design the optimal resonator for the variety of site condition, it is necessary to research about the various cases applying different shape, arrangement, and size of resonator as further study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.593-601
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• 2021

The axial fan is an element of a blower used for ventilation in various industrial fields. Many studies on aerodynamic performance have been conducted to assess axial fans using fluid dynamics. The subject was a large axial fan size, 1800 mm in diameter with 100 horsepower. The blower's axial fan consisted of blades, hubs, hub caps, and bosses are important components. The blade design has a great influence on the aerodynamic performance. 3D point data is extracted using an aerodynamic performance prediction program, and a 3D modeling shape is generated. The blades and hubs, which are important components, can be easily modified if processed by cutting owing to the environment in which blades and hubs are manufactured through die casting or gravity casting. In this study, the structural safety of components and the analysis results of weak areas at the rated operating speed of the axial fan were verified using the maximum stress and safety factor. The tip clearance reflected in the design was the rotation of the blade. To check whether there is interference with other components, the displacement result was derived to verify the structural safety of the axial fan.

• Journal of Korean Medicine for Obesity Research
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• v.20 no.2
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• pp.178-192
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• 2020

Objectives: The present study aimed to compare the impacts of cognitive behavioral therapy (CBT) and behavioral treatment (BT) on weight loss and psychological outcomes among patients with three different subtypes of obesity: simple obesity, obesity with binge eating disorder, and obesity with depression. Methods: Embase, PubMed, the Cochrane Central Register of Controlled Trials, Research Information Sharing Service, and Korean Studies Information Service System were systematically searched for randomized controlled trials conducted on or before May 2020, that used CBT to treat obesity. Methodological quality was assessed using Cochrane's risk of bias tool 2 and publication bias was evaluated through the funnel plot using the trim and fill method, Egger's test, and Begg and Mazumdar rank correlation test. A meta-analysis was conducted using a random-effects model and the standardized mean difference with 95% confidence interval (CI) was used to determine effect size. Results: Twenty-one randomized controlled trials with a total of 22 intervention arms and 2,590 patients were included. Our study results revealed that the effects of CBT, compared with BT, on weight loss distinctly differed across all patient subgroups. In the simple obesity group, CBT was more effective than BT (Hedges' g=0.138, CI=0.012~0.264); however, in the obesity with binge eating disorder group, BT was more effective than CBT (Hedges' g=-0.228, CI=-0.418~-0.038); in the obesity with depression group, the effect of CBT was not statistically different from that of BT (Hedges' g=0.276, CI=-0.307~0.859). Further studies with larger sample sizes are required to confirm the outcomes observed in this study. Conclusions: Our results indicated that the effects of CBT on obesity treatment vary based on patient subtype. Therefore, our findings suggest that CBT or BT should be selectively recommended as a treatment strategy for different obesity subtypes.

• 한국사회정책
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• v.20 no.2
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• pp.261-304
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• 2013

This article is aiming intensively to analyze the polarizing tendency of labour market and social integration. The polarization of labour market is being regarded as one of the hottest issues not less important than those problems of economic growth, employment, income distribution and national security etc. in the national policy. In this article, we will first follow up the important phenomena of labour market polarization and the background as well as its consequence. Especially, it asks if the present labour policy in the new government which is now being concentrated on the improvement of employment rate(from the present 63% to the 70% in the future) could deserve to diminish the polarization of labour market in korea. At one side, this article makes the special attention on the diversifying tendency of labour market and the various phenomena of fragmentation and segmentation in the labour market according to the forms and types of employment and according to the employee's status as much as the company's size. At the other side, it emphasizes that to overcome the polarization of labour market should require the wide reform from the legal measure to the improvement of the wage system, and the qualification system and the social investment as well as the human resource development. Furthermore, this article stresses the importance of integrative approach between the active market policy and the social policy instead of choosing each policy option, seperatively.

• 한국사회정책
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• v.24 no.2
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• pp.87-126
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• 2017

This study aims to examine the level of precariousness among young adults in South Korea and analyze the factors affecting their subjective well-being by adopting the three forms of precariousness suggested by Rodgers(1989) such as lack of resource, uncertainty and disempowerment as its analytical framework. Structural Equation Model was used for analyzing the path model of self-rated health, income level and social support(three forms of resource) affecting subjective wellbeing through uncertainty and disempowerment. Study population include young adults aged between 19 to 34 with a sample size of 415 using data of the 8th wave of the Korean General Social Survey(KGSS), 2010. Study population is divided into lower-age group (aged between 19-26) and upper-age group (aged between 27-34) in order to examine the differences between age groups by using Multiple Group Analysis. Study results show that three forms of resources, uncertainty and disempowerment had direct effect on the subjective well-being of South Korean young adults and disempowerment had the most significant effect among the factors. In addition, self-rated health and income level had indirect effect on subjective well-being through both uncertainty and disempowerment while social support had indirect effect on subjective well-being only through disempowerment. Results from the Multiple Group Analysis indicate that among the two age groups, income level only has a significant effect on subjective well-being in the upper-age group. In addition, disempowerment had greater effect on subjective wellbeing among upper-age group than the lower-age group. Based on the study results, this paper suggested policy implications and discussion for further research.