• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.506-514
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• 2014

Recently the interest about the vortex intakes are rapidly increased because of its performance to drain a plenty of collected storm water at a time. The tangential intake a kind of vortex intakes is very applicable because this type is very simple and little against other types, but it has a big weakness that the vortex flow is not been rarely created below the design discharge. In this study, the characteristics of a tangential intake and two kinds of a newly suggested compound section type intake are analyzed by the 3D numerical modeling based on theories about the control shift and free drainage condition. The analysis focused on the flow condition, flow surface formation, depth-discharge relation, area ratio of air core. Based on this study, the mild-sloped compound section type intake is the optimal, but steep-sloped compound section type is also the optional for the small design discharge.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.189-196
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• 2017

This study investigates customer satisfaction with full service carriers (FSC) and low cost carriers (LCC) using social media sentiment evaluation. From 2008 to 2016, a total of 77,591 tweets about two FSC and six LCC were aggregated and classified as per airline choice factors. Sentiment evaluation was employed to assess customer satisfaction by three appraisers. The results showed that customer satisfaction with LCC was significantly higher (p<0.001) compared to FSC. Furthermore, overall customer satisfaction with both FSC and LCC has been facing a consistent downward trend since the last seven years. The results also highlighted low customer satisfaction with respect to booking and flight operation factors, and a steep decline in customer satisfaction across booking, onboard services, and marketing factors for FSC. The results of this study have practical implications for the airline industry, which can use this quantitative data to improve customer satisfaction with FSC and LCC.

• Journal of the Korean earth science society
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• v.34 no.7
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• pp.605-614
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• 2013

Most steep slope failures tend to take place in geographically unstable areas. Mt. Baekdusan is known as a potentially active volcano in a typical mountainous terrain. This study prepared a digital elevation model of Mt. Baekdusan area and created a hazard map based on topographical factors and structural lineament analysis. Factors used in vulnerability analysis included geographical data involving aspect and slope distribution, as well as contributory area of upslope, tangential gradient curvature, profile gradient curvature, and the distribution of wetness index among the elements that comprise topography. In addition, the stability analysis was conducted based on the lineament intensity map. Concerning the disaster vulnerability of Mt. Baekdusan region, the south and south west area of Mt. Baekdusan has a highest risk of disaster (grade 4-5) while the risk level decreases in the north eastern region.

• The Journal of Korean Institute for Practical Engineering Education
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• v.4 no.2
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• pp.75-83
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• 2012

Due to the proliferation of smart devices, worldwide market growth of e-book content steep, but the domestic market shows relatively low growth rate and small size. In this study, a distribution modeling of the e-book business as a way to solve the problem of the domestic market of disabled was carried out to analyze the Amazon.com and Apple's e-book content distribution structure of the active leader in the U.S. market. And we tried to suggest a solution by investigation and analysis of the college students's receptive attitude on the e-book content as the main target to enable the markets based on the interest for publication. In adoption attitude survey, mainly low-readability and lack of content problem were reasons not to accommodate. There is a need to improve the quantity and quality of content through with technological advances and market participation together. For more participation, we expect to take advantage of the results of this study to establish or improve the systematic distribution structure.

• Tunnel and Underground Space
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• v.23 no.1
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• pp.31-41
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• 2013

Graphical method has been widely applied to the prediction of subsidence area, and is known to have advantages in analysis of trough subsidence which is common in horizontally seamed mine area. However, it is reported that most of the ore bodies in Korea are geologically inclined from sub-horizontal to steep, and therefore, the sinkhole subsidence is frequent in abandoned mine area. For these reasons, it is not to be desired that graphical method is applied for predicting the subsidence occurrence. This paper describes the results of subsidence zone prediction considering the dip direction and the opposite direction of inclined ore bodies from the case studies on the 163 subsidence occurrence regions. The results show also the assumed angle which can define the range of subsidence in the surface area. In conclusion, the limit of this angle is suggested after taking into account the comparison with graphical method and the application to the case histories.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.3
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• pp.313-321
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• 2012

Korea has been continuously affected by landslides, as 70% of the land is covered by mountains and most of annual rainfall concentrates between June and September. Recently, abrupt climate change affects the increase of landslide occurrence. Gangwon region is especially suffered by landslide damages, because the most of the part is mountainous, steep, and having shallow soil. In this study, a landslide risk assessment model was developed by applying logistic regression to the various data of Duksan-ri, Inje-eup, Inje-gun, Gangwon-do, which has suffered massive landslide triggered by heavy rain in July 2006. The information collected from field investigation and aerial photos right after the landslide of study area were stored in GIS DB for analysis. Slope gradient entered in two ways-as categorical variable and as linear variable. Error matrix for each case was made, and developed model showed the classification accuracy of 81.4% and 81.9%, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2411-2417
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• 2012

Globally, the emergence of smart phones vitalized the ecosystem of mobile data service industry. Consequentially, mobile data traffic has been explosively growing and the speed of growth will be more steep. New spectrum will be required in order to properly accommodate the explosively growing mobile data traffic. However, it will be difficult to acquire a sufficient guard band between different frequency bands because the range of frequency which is suitable for wireless communications is limited. Thus, the performance degradation caused by inter-band interference will be one of challenging problems in the next generation mobile communication systems. In this paper, we analyze the performance degradation caused by inter-band interference by computer simulations in various environments. Our results show that the impact of the inter-band interference is more critical when own signal is poor or its own interference from neighboring cells is low.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.2
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• pp.139-154
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• 2011

The golden rule of CRM should be core customers. They show such passionate partnership with the company that they actively put forth their opinion to improve products and service through voluntary pro-company activities and participate in the development of new products through open innovation. Therefore, the top priority of a company should be given to defining its core customers and accurately understanding and managing them, which would contribute to the growth of the company. It has become more important nowadays how to manage a long-term customer relationship, for it can assure the company of increased income in spite of steep competition with rival companies. Therefore strong customer relationship is an important means of proving the company with competitive edge and maximizing company income.

• Journal of The Geomorphological Association of Korea
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• v.17 no.1
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• pp.1-14
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• 2010

This paper deals with the classification and distribution of geomorphic surfaces and analysis on effects of geomorphic processes on the landforms in the inaccessable DMZ (Demilitarized Zone) to Wonsan Bay of East Sea coast of Chugaryeong Rift Valley, Central Korea. DEM (Digital Elevation Model) and Landsat images are used for the above anlaysis. The geomorphic surfaces are classified by TPI (Topographical Position Index) for the analysis of the convexity and concavity calculated using topographical elements such as elevation, steepness, and relief. In the Chugayreong Valley, 10 geomorphic surfaces are classified as steep valley, shallow valley, upland drainage, U-shaped valley, plain, open slope, upper slope, local ridge, midslope ridge, and high ridge. Zonal Statistics presents average characteristics of geomorphological processes of surfaces by the relationships between bedrock and relief, surface and relief, and between surface and NDVI. So, these analysis can help to understand geomorphological process such as dissection of lava plateau and watershed divide evolution.

• Journal of Korean Society of Forest Science
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• v.113 no.2
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• pp.153-163
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• 2024

Since the onset of the COVID-19 pandemic, there has been a significant shift in the lifestyle patterns of the populace across various domains. Concerns surrounding COVID-19 have emerged as pivotal catalysts of change in recreational habits with people giving a particular preference for environments with low population density and increased openness. This trend has resulted in an uptick in excursions to natural reserves, coastlines, and parks. However, during the peak of infectious outbreaks, widespread adherence to social distancing measures has precipitated a steep decline in tourist footfall across natural recreation forests, exacerbating financial deficits to a considerable extent. Thus, this research sought to compare and analyze the operational efficacy and productivity of national, public, and private natural recreation forests pre- and post-COVID-19 pandemic by utilizing non-parametric methodologies, such as data envelopment analysis and the Malmquist productivity index analysis. The objective was to identify the factors contributing to the decreases in efficiency and productivity and ultimately offer nuanced recommendations tailored to respective administrative bodies. This study's distinctive focus on the analysis of management efficiency and productivity in natural recreation forests nationwide offers significant academic and practical relevance.