• Journal of KIISE
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• v.42 no.4
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• pp.504-511
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• 2015

Recently, the amount of data is rapidly increasing with the popularity of the SNS and the development of mobile technology. So, it has been actively studied for the effective data analysis schemes of the large amounts of data. One of the typical schemes is a Voronoi diagram based on kNN join algorithm (VkNN-join) using MapReduce. For two datasets R and S, VkNN-join can reduce the time of the join query processing involving big data because it selects the corresponding subset Sj for each Ri and processes the query with them. However, VkNN-join requires a high computational cost for constructing the Voronoi diagram. Moreover, the computational overhead of the VkNN-join is high because the number of the candidate cells increases as the value of the k increases. In order to solve these problems, we propose a MapReduce-based kNN-join query processing algorithm for analyzing the large amounts of data. Using the seed-based dynamic partitioning, our algorithm can reduce the overhead for constructing the index structure. Also, it can reduce the computational overhead to find the candidate partitions by selecting corresponding partitions with the average distance between two seeds. We show that our algorithm has better performance than the existing scheme in terms of the query processing time.

• Journal of Distribution Science
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• v.13 no.10
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• pp.135-142
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• 2015

Purpose - Following the speedy development of the smart phone industry, tourism companies started to increase their brand recognition and sales volume by adopting mobile applications. However, applications for tourism industries are still insignificant. This study tries to analyze empirical evidence from Korean and Chinese consumers who have used mobile tour applications. By using an expansion of the technology acceptance model (TAM), this study will find what factors have effects on user intention for mobile tour applications. The findings will be helpful for the development of mobile tour applications and the tourism industries. Research design, data, and methodology - This study uses the TAM, which was presented by Davis in 1989. This study uses consumer acceptance level, consumer choice attitude, and use intention as the basic variables to fit to the TAM, and adopts choice content quality, brand value, and usage motivation as additional variables to analyze. This study has developed several hypotheses and collected data from 620 users who used mobile applications for tourism during April 1 to April 30, 2015. A total of 612 valid questionnaires were collected and used in the data analysis. The data was analyzed with structural equation modeling using SPSS Win/pc and Amos 22.0. Results - The findings can be summarized as follows: First, the content quality affects the consumer acceptance degree and choice attitude. Second, the brand value has a directly positive effect on the consumer acceptance degree and choice attitude. It is clear that the content quality and brand value play important roles in raising consumer acceptance and choice attitude. Third, usage motivation has no effect on the consumer acceptance degree and choice attitude. Fourth, the acceptance degree does not have any effect on the consumer choice attitude. Fifth, the acceptance degree affects the use intention. Last, the consumer choice attitude affects the use intentions. This indicates that consumer acceptance and choice attitude must both be achieved to induce use intention among consumers. Finally, the effects of the mobile tour application content quality and brand value on consumer acceptance degree and choice attitude were confirmed. Additionally, the effects of the consumer acceptance degree and choice attitude on use intentions were analyzed. Conclusion - It is not meaningful for tourism marketing to launch tour applications in the mobile market without understanding tourism consumer characteristics. When developing mobile tour applications, companies should focus on the characters of consumer choice attitudes as high quality, high brand value, usefulness, and ease of mobile tour applications. This study has limitations in that it did not consider negative factors such as perceived risks or analyze whether there are differences between Korean and Chinese consumers. In the future, we will consider equipping the same mobile tour applications commonly used by both Korean and Chinese consumers, and then examine negative factors as well as the differences in mobile tour applications between Korean and Chinese consumers.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.1
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• pp.3-14
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• 2015

As buildings in the downtown area, such as the complex building connected to the skyscraper and the underground facility, have become large and complex, the range of target domain of the space information service is rapidly expanding to the interior space; it is considered that this change will create various demands of service such as the indoor geospatial information base safety, the management of facility, and the interior navigation in the future, along with spread of mobile devices and development of IT technology. As for the indoor geospatial information, however, there is no certification standard of the established indoor geospatial information data quality, so preparing the certification standard is urgent. Thus, this study reviewed foreign and domestic research cases and prepared measures for quality verification of the indoor geospatial information to conduct a verification test of the Yeongdeungpo Station indoor geospatial information, established in 2014. As a result, through the verification test of the method and standard of the indoor geospatial information quality certification suggested by this research, it was identified that the uniform and higher quality data could be classified, and the types of error high frequently occurring could be investigated. These results are expected to be utilized as the basic data for establishing quality certification system for the indoor geospatial information in the future.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.2
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• pp.3-8
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• 2011

Recently, the demand for enterprise for service map providing and portal site services of a 3D virtual city model for public users has been expanding. Also, accuracy of the data, transfer rate and the update for the update for the lapse of time emerge are considered as more impertant factors, by providing 3D information with the web or mobile devices. With the latest technology, we have seen various 3D data through the web. With the VRML progressing actively, because it can provide a virtual display of the world and all aspects of interaction with web. It offers installation of simple plug-in without extra cost on the web. LiDAR system can obtain spatial data easily and accurately, as supprted by numerous researches and applications. However, in general, LiDAR data is obtained in the form of an irregular point cloud. So, in case of using data without converting, high processor is needed for presenting 2D forms from point data composed of 3D data and the data increase. This study expresses urban LiDAR data in 3D, 2D raster data that was applied by compressing algorithm that was used for solving the problems of large storage space and processing. For expressing 3D, algorithm that converts compressed LiDAR data into code Suited to VRML was made. Finally, urban area was expressed in 3D with expressing ground and feature separately.

• The Journal of the Korea Contents Association
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• v.11 no.5
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• pp.148-156
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• 2011

Recently, an introduction of the cloud computing causes rapid changes in every aspect of the internet environments including hardware, operating systems, applications, and their services. As the cloud computing environment based on SaaS are being developed to a form in which web platform technology and web cloud services are converged. The digital library system also has been being developed to a service model optimized to SaaS based cloud computing environment, which are different from ASP technology. From the web interface point of view, user customization of the SaaS based cloud computing environment is the most important fact. Therefore, this research work suggests a customized web interface considering usability and accessibility so that enterprises and individual users can be able to do an effortless internet browsing under the cloud computing environment. For this purpose, usability tests were carried out as the user customized web interface design were developed and applied to the LinkSaaS website. This paper work lastly presents an UI environment on which customized interface design for individual users can be formulated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.768-779
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• 2017

Recently, the great number of mobile devices causes excessive data/control traffic problems in the centralized LTE/EPC network and such dramatically increased traffic is emerging as a critical issue. In the Centralized Mobility Management (CMM) based LTE/EPC network, the Packet Data Network Gateway (P-GW) plays the centralized mobility anchor role and it accommodates most of data traffic. To solve this problem, the IETF has proposed the Distributed Mobility Management (DMM) scheme, but it has only focused on the data traffic load balancing and could not solve the control traffic overload problem. In this paper, therefore, we propose a new SDN based hybrid CMM/DMM Mobility Management (C-DMM) architecture based on Packet Network Edge Gateway (P-EGW), and introduce a selection scheme between CMM and DMM according to a device's mobility and the number of PDN connections. In order to prove the efficiency of the proposed architecture and scheme, we compare the data traffic processing load and the control traffic processing load over each scheme by emulating them in the ONOS controller and the Mininet environment.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.5
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• pp.177-188
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• 2018

The scale of graph data has been increased rapidly because of the growth of mobile Internet applications and the proliferation of social network services. This brings upon the imminent necessity of efficient distributed and parallel graph processing approach since the size of these large-scale graphs are easily over a capacity of a single machine. Currently, there are two popular parallel graph processing approaches, vertex-centric graph processing and block centric processing. While a vertex-centric graph processing approach can easily be applied to the parallel processing system, a block-centric graph processing approach is proposed to compensate the drawbacks of the vertex-centric approach. In these systems, the initial quality of graph partition affects to the overall performance significantly. However, it is a very difficult problem to divide the graph into optimal states at the initial phase. Thus, several dynamic load balancing techniques have been studied that suggest the progressive partitioning during the graph processing time. In this paper, we present a load balancing algorithms for the block-centric graph processing approach where most of dynamic load balancing techniques are focused on vertex-centric systems. Our proposed algorithm focus on an improvement of the graph partition quality by dynamically reassigning blocks in runtime, and suggests block split strategy for escaping local optimum solution.

• Spatial Information Research
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• v.21 no.4
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• pp.71-81
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• 2013

Due to explosively increasing utilization in spatial information and a rapid development in geospatial technology related to national territorial and housing, there are increasing demands for converging spatial information on not only urban planning and real estate data but also newly generated data from smart phone, GPS to achieve comparative advantage of national territory. In this paper, we prospect the utilization of Converged Spatial Information(CSI) to future national territorial planning for the purpose of enhancing territorial competitiveness. For this purpose, considering the Korea Land and Housing corporation(LH) takes charge most of government's land and housing development projects, CSI usage of this company's 6 future business domains until 2029 were used as a case study. Also, 7 CSIs derived from literature review were surveyed to find the degree of CSI utilization in the national territorial future. In the analysis result, it was found that 3D data and mobile data among others have higher degree of utilization, and urban and regional development is the most highly utilizable domain for CSIs. After all, to revitalize the use of CSI in national territorial future, it is required to do a balanced construction of territorial use spatial information about marine use, coastal use, underground space besides land use.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.1
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• pp.29-37
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• 2008

With the rapid development of display technology as well as the diversity of display, image quality assessment plays an important role in display color reproduction. The image quality has described by objective evaluation based on the physical measured data, such as contrast ratio, color reproduction range, color temperature, and gamma characteristics, etc., however, the final judgement is achieved by perceptual quality assessment of observers. Therefore, it is necessary to investigate the relationship between physical performance of display and perceptual image quality. Thus, in order to evaluate objectively the color reproduction characteristics of two mobile displays, TFT-LCD and AMOLED, we measured the darkroom contrast ratio of full screen, luminance and color temperature of full-screen white, full-screen gray and color linearity, tone reproduction of color scales for each RGB primary, and color reproduction range. Then the pair-wise comparison is implemented for image experts and naive observers not only to judge their preference on principal evaluation attributes but also to subjectively describe perceived image quality. Through two evaluation processes, we derived the objective bases that can prove the results of subjective image quality assessment by interconnecting physical factors that have influence on observers' preference judgements. Finally, this paper provided important information for improving the image quality and increasing preference from an observer's point of view.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.180-189
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• 2014

Display quality assessment has been a long standing issue due to the diversity of display devices and the rapid growth of display technology. The conventional display quality assessment methods are mostly those methods which evaluate qualities of a display by measuring physical quantities, but the results from the methods are not equal to the perceived results which are acquired with subjective experiments. Thus, we need to solve the above contrariety as well as establish the quantitative correlation between physical and perceived results. This paper proposes the systematic method of evaluating relative perceived qualities among various display devices and quantifies these relative perceived qualities. The proposed method is based on Analytic Network Process(ANP), which is one of the most popular decision making methods in the business administration field. We also adopted three evaluation criteria, which consist of color, shape and depth, in order to reflect the human visual system and chose eight sub-criteria related to display characteristics via question investigation. We carried out a subjective experiment and the proposed method which evaluated perceived qualities of two display devices(TFT-LCD, OLED) in order to prove the similarity between their results. As a result, it is proved that the order relationship between perceived qualities was the same as the order of results got through the subjective experiment.