• Journal of Information Technology and Architecture
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• v.11 no.1
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• pp.63-73
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• 2014

As the advance of WWW, unstructured data including texts are taking users' interests more and more. These unstructured data created by WWW users represent users' subjective opinions thus we can get very useful information such as users' personal tastes or perspectives from them if we analyze appropriately. In this paper, we provide various analysis efficiently for unstructured text documents by taking advantage of OLAP (On-Line Analytical Processing) multidimensional cube technology. OLAP cubes have been widely used for the multidimensional analysis for structured data such as simple alphabetic and numberic data but they didn't have used for unstructured data consisting of long texts. In order to provide multidimensional analysis for unstructured text data, however, Text Cube model has been proposed precently. It incorporates term frequency and inverted index as measurements to search and analyze text databases which play key roles in information retrieval. The primary goal of this paper is to apply this text cube model to a real data set from in an Internet site sharing hotel information and to provide multidimensional analysis for users' reviews on hotels written in texts. To achieve this goal, we first build text cubes for the hotel review data. By using the text cubes, we design and implement the system which provides multidimensional keyword search features to search and to analyze review texts on various dimensions. This system will be able to help users to get valuable guest-subjective summary information easily. Furthermore, this paper evaluats the proposed systems through various experiments and it reveals the effectiveness of the system.

• Journal of Navigation and Port Research
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• v.38 no.4
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• pp.429-435
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• 2014

In general, Introducing of the Designated Manager System (DMS) of public facilities has been promoted as part of administrative reforms for planning improvement of service for customers by a private and budget cuts of operations management. DMS has begun to be introduced to the public marina facilities in earnest in 2006, it is evaluated positive about efficiency in terms of business(budget cuts). However, there is no discussion about efficiency (likes service satisfaction of client-side) from the marina whose major job is service. The primary purpose of this study is to clarify the benefits and challenges as a result of the Designated Manager System (DMS) launch implemented by local governments, following the relevant amendments to the Local Government Law. The second purpose is to clarify, from the viewpoint of users, what changes have taken place after the DMS launch, focusing on public marinas operated under the DMS. As for the primary purpose, the study is intended to clarify the economic benefits of the DMS and the significance of the DMS launch at a prefectural government level. This will help us assess whether it would be worthwhile to encourage private companies or non-profit organizations (NPO) to participate in the management and operation of public facilities under the DMS scheme. Most of the studies to date have examined the benefits of the DMS launch, focusing on the economic benefits for local governments. This study is intended to clarify the benefits and disadvantages to users of the DMS launch from the viewpoint of users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.1044-1053
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• 2016

In this paper, we consider the secondary users (SUs) who are capable of harvesting energy from ambient radio frequency (RF) signals and are allowed to sequentially sense up to 2 different channels to find out idle channels not occupied by the primary users (PUs). The EH SUs are permitted to transmit data packets only if both idle channels and sufficient energy are available. Compared with traditional SUs, the EH SUs consume energy with data transmission and also harvest energy without additional energy supply. Consequently, the battery state is expected to be fluctuated due to energy consumption and harvesting, and therefore we develop a Markov battery model to provide energy variations at the 2-channel sensing EH SUs. With the proposed battery model, we derive the steady-state probability that the EH SUs completely run out of energy, and the achievable throughput of EH SUs is derived accordingly. To evaluate the proposed Markov battery model, the Monte-Carlo simulation was performed to validate the accuracy of energy outage probability and achievable throughput at the 2-channel sensing EH SUs.

• Journal of The Korean Association of Information Education
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• v.15 no.1
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• pp.155-162
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• 2011

It is proven that students learn more effectively when they apply Empirical knowledge which they have experienced or been facing. Therefore, the customized training supporting systems for information communication ethics education for primary school is developed. It provide resources on the internet such as teaching methodology, teaching materials, real life examples and applications related to information communication ethics education to the teachers. Each resource is categorized according to the topic and it improved information communication ethics education by providing customized resources on the topic. It is also helpful for users to select necessary resources by informing the suitability between the subject and the resources and to lift the burden on searching the data.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.2
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• pp.104-109
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• 2016

In this paper, a localization method for multiple robots based on Bayesian inference is proposed when multiple robots adopting multi-RAT (Radio Access Technology) communications exist in cognitive radio networks. Multiple robots are separately defined by primary and secondary users as in conventional mobile communications system. In addition, the heterogeneous spectrum environment is considered in this paper. To improve the performance of localization for multiple robots, a realistic multiple primary user distribution is explained by using the probabilistic graphical model, and then we introduce the Gibbs sampler strategy based on Bayesian inference. In addition, the secondary user selection minimizing the value of GDOP (Geometric Dilution of Precision) is also proposed in order to overcome the limitations of localization accuracy with Gibbs sampling. Via the simulation results, we can show that the proposed localization method based on GDOP enhances the accuracy of localization for multiple robots. Furthermore, it can also be verified from the simulation results that localization performance is significantly improved with increasing number of observation samples when the GDOP is considered.

• Journal of The Korean Association of Information Education
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• v.1 no.1
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• pp.49-59
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• 1997

In this thesis, To provide the base of effective data access methods, performance of some indexing techniques used gent-Tally are compared. They are classified as primary key and multikey. For primary key method, made a comparative analysis on Static index. Dynamic index and Hashing. For multikey indexing method K-d tree, K-d-B tree, Inverted file and Grid file of which characteristics are compared. In many applications, multikey indexings are more requested, but are not supplied enough. So, to satisfy users' request - more fast, more exact and to be applied according to the trend of being huge database systems, it is requested more study about multikey data access methods.

• Journal of the Korea Furniture Society
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• v.18 no.1
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• pp.31-38
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• 2007

The most important issue of today in design genre is the comprehensive design that overcomes the limitations of the rational and logical designs of functionalism that has had influences in entire 20th century and encompasses even the emotional aspect of humans. The emotional design factors in furniture designs will be analyzed in order to analyze their effects and values on the consumers of present times. The emotional uses of the patterns with the motive of nature expressing papers, flowers, wood textures, natural phenomena etc as they are and the colors with the vivid feeling of primary colors represent more dynamic and cheerful life style and the designs are characterized by the warm primary colors that give the feeling that the nature has been transferred to the designs as it is. Diverse materials such as leather, fur, fabric and the materials with soft and flexible feeling such as silicone material have been used more widely and they are used as the materials expressing freedom not being formalized. The designs that can produce diverse spaces desired by users by gathering unit modules can be said to be the outcome of the emotional designs combined with the needs of modern peoples that aspire their own designs.

• Journal of Information Technology Services
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• v.17 no.2
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• pp.111-128
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• 2018

About 3.9 million apps and 24 primary categories can be approved on Apple iTunes Store. Making accurate categorization can potentially receive many benefits for developers, app stores, and users, such as improving discoverability and receiving long-term revenue. However, current categorization problems may cause usage inefficiency and confusion, especially for cross-attribution, etc. This study focused on evaluating the reliability of app categorization on Apple iTunes Store by using several rounds of inter-rater reliability statistics, locating categorization problems based on Machine Learning, and making more accurate suggestions about representative functionality stems for each primary category. A mixed methods research was performed and total 4905 popular apps were observed. The original categorization was proved to be substantial reliable but need further improvement. The representative functionality stems for each category were identified. This paper may provide some fusion research experience and methodological suggestions in categorization research field and improve app store's categorization in discoverability.

• Journal of Broadcast Engineering
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• v.14 no.1
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• pp.89-92
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• 2009

In this paper, we discuss the BBA based power scaling scheme in cognitive radio technique for WPAN system. We focus on Cognitive Radio environment which is currently ongoing standard procedure and is able to focus on future communication and show the transmitted power scaling of CR user. We suggest the available communication method of CR user, while it is simultaneously satisfying both minimum interference of PU(Primary User) and possible communication of CR user. The method is using the BBA, and we show several merits in face of received SINR. and we prove that CR vary its transmit power while maintaining a guarantee of service to primary users.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1279-1300
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• 2017

In the interweave cognitive networks, the interference from the primary user degrades the performance of the cognitive user transmissions. In this paper, we propose an adaptive cooperation scheme in the interweave cognitive networks to improve the performance of the cognitive user transmissions. In the proposed scheme for the bidirectional communication of two end-source cognitive users, the bidirectional communication is completed through the non-relay direct transmission, the one-way relaying cooperation transmission, and the two-way relaying cooperation transmission depending on the limited feedback from the end-sources. For the performance analysis of the proposed scheme, we derive the outage probability and the finite-SNR diversity multiplexing tradeoff (f-DMT) in a closed form, considering the imperfect spectrum sensing, the interference from the primary user, and the power allocation between the relay and the end-sources. The results show that compared with the direct transmissions (DT), the pure one-way relaying transmissions (POWRT), and the pure two-way relaying transmissions (PTWRT), the proposed scheme has better outage performance. In terms of the f-DMT, the proposed scheme outperforms the full cooperation transmissions of the POWRT and PTWRT.