• Journal of Internet Computing and Services
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• v.6 no.2
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• pp.69-84
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• 2005

As the Internet users are increasing rapidly, a cluster web server system is attracted by many researchers and Internet service providers. The cluster web server has been developed to efficiently support a larger number of users as well as to provide high scalable and available system. In order to provide the high performance in the cluster web server, efficient load distribution is important, and recently many content-aware request distribution techniques have been proposed. In this paper, we propose a new content-aware load balancing technique that can evenly distribute the workload to each node in the cluster web server. The proposed technique is based on the hash histogram transformation, in which each URL entry of the web log file is hashed, and the access frequency and file size are accumulated as a histogram. Each user request is assigned into a node by mapping of (hashed value-server node) in the histogram transformation. In the proposed technique, the histogram is updated periodically and then the even distribution of user requests can be maintained continuously. In addition to the load balancing, our technique can exploit the cache effect to improve the performance. The simulation results show that the performance of our technique is quite better than that of the traditional round-robin method and we can improve the performance more than $10\%$ compared with the existing workload-aware load balancing(WARD) method.

• Journal of Internet Computing and Services
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• v.15 no.4
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• pp.125-133
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• 2014

The column-oriented database storage is a very advanced model for large-volume data analysis systems because of its superior I/O performance. Traditional data storages exploit row-oriented storage where the attributes of a record are placed contiguously in hard disk for fast write operations. However, for search-mostly datawarehouse systems, column-oriented storage has become a more proper model because of its superior read performance. Recently, solid state drive using MLC flash memory is largely recognized as the preferred storage media for high-speed data analysis systems. The features of non-volatility, low power consumption, and fast access time for read operations are sufficient grounds to support flash memory as major storage components of modern database servers. However, we need to improve traditional transaction management scheme due to the relatively slow characteristics of column compression and flash operation as compared to RAM memory. In this research, we propose a new scheme called Column-aware Multi-Version Locking (CaMVL) scheme for efficient transaction processing. CaMVL improves transaction performance by using compression lock and multi version reads for efficiently handling slow flash write/erase operation in lock management process. We also propose a simulation model to show the performance of CaMVL. Based on the results of the performance evaluation, we conclude that CaMVL scheme outperforms the traditional scheme.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.47-53
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• 2018

This paper proposes a method to express an MP3 audio file by a series of color QR codes which can be printed on the paper. Moreover, the method can compress the data considerably. Firstly, an MP3 file is divided into many small files which have maximum capacity of binary file of a QR code. Secondly, the multiple files are converted to multiple black-and-white QR codes. Lastly, every three QR codes are combined into color QR codes. When combining, each of three black-and-white QR codes are regarded as red, green, blue components respectively. In this method, the areas of a color QR code where two QR codes are overlapped are expressed by the colors Cyan, Magenta and Yellow. And the areas where three components are overlapped are expressed by white color. Contrarily, the areas that no components are overlapped are expressed by white color. Experimentation result shows that an MP3 file with 8.5MB the original MP3 files are compressed with the compression rate around 15.7. This method has the advantage that can be used in the environments that the internet access is impossible.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.1_2
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• pp.137-146
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• 2006

Traditional live video streaming systems support the limited field of view (FOV) of image to the remote users. A server system based on the pan/tilt camera provides a user with wide view by changing the view direction of the camera mechanically. But, when many clients try to access to the server, this system can not offer their own view to every user simultaneously, and moreover it has the delay by camera motion. In order to offer wide views to several users, we propose new streaming system using the panorama image that has wide view. Our system is a kind of implementation of software pan/tilt camera. The server acquires panorama video and sends a part of the video to clients. Then, each client can control their own view. We need the effective way to reduce the average transmission data size and server burden to the compression because generally the full size of panorama video is too big to be served by the real-time streaming. To solve this problem, we propose an strip-based video compression and adaptive transmission of the compressed multiple strip videos. Experimental results show that our system can be adapted quickly to the change of view and the number of clients. Furthermore, proposed method effectively reduce the transmission data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.366-373
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• 2020

This study explored the factors associated with dependence among smartphone-dependent adults in their 20s. The data was derived from the 2017 survey on smartphone over-dependence conducted by the Ministry of Science and ICT and the National Information Society Agency. The participants were 879 adults in their 20s. The data was analyzed by frequencies, percentages, means, standard deviations, independent t-tests, Pearson's correlation coefficients, and multiple regression analysis. The results revealed instant messengers as the most used application by participants. Participants in the high risk category of dependence also used SNS (Social Networking Services), music, and games more than those in the potential risk category. The more serious the dependence, the greater the frequency of smartphone use (β=.16, p=.000), and use of games (β=.10, p=.028), webtoons (β=.14, p=.004), SNS (β=.09, p=.047), and financial transactions (β=.17, p=.000). They did not recognize their smartphone dependence when it was relatively low. However, when this became serious, they then realized that they depended on the smartphone more than others. That means that it is not easy for adults to recognize their smartphone dependence on their own. However, recognition of the problem is the first step for adults to solve their problems. A program that evaluates their problematic smartphone use should be installed and used on all smartphones.

• Journal of Convergence for Information Technology
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• v.10 no.4
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• pp.184-193
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• 2020

The purposes of this paper are to find the effects of beauty shop online motivations on the convenience of reservation system, to investigate the convenience of reservation system on satisfaction, and to determine the effects of satisfaction on word-of-mouth behaviors. Based on the results, there are three factors in the motivations: diversion, service-prioritized, and impulse-driven tendencies. Also, there are five factors in the reservation convenience perception: efficiency of decision-making, easy monetary transaction, overall convenience, accessibility, and effortless nature of rewarding system. In terms of the convenience of online booking, the access convenience was found that as the motivation diversion and the service-prioritized motivation higher and as the impulse reservation motivation lower. Furthermore, this paper concludes that offered by online beauty service reservation systems, and higher satisfaction rate leads to higher review behaviours.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.3
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• pp.105-112
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• 2017

PCI Express is a bus technology that connects the processor and the peripheral I/O devices that widely used as an industry standard because it has the characteristics of high-speed, low power. In addition, PCI Express is system interconnect technology such as Ethernet and Infiniband used in high-performance computing and computer cluster. PGAS(partitioned global address space) programming model is often used to implement the one-sided RDMA(remote direct memory access) from multi-host systems, such as computer clusters. In this paper, we design and implement a OpenSHMEM API based on PCI Express maintaining the existing features of OpenSHMEM to implement RDMA based on PCI Express. We perform experiment with implemented OpenSHMEM API through a matrix multiplication example from system which PCs connected with NTB(non-transparent bridge) technology of PCI Express. The PCI Express interconnection network is currently very expensive and is not yet widely available to the general public. Nevertheless, we actually implemented and evaluated a PCI Express based interconnection network on the RDK evaluation board. In addition, we have implemented the OpenSHMEM software stack, which is of great interest recently.

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.459-468
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• 2013

With advancements in augmented reality technology, attempts to apply it in various fields have increased. With advancements in information technology and a growth in the number of Korean learners in Korea and abroad, there is a growing demand for state-of-the-art Korean learning contents. Because the Korean learning contents developed using augmented reality have been found insufficient, this paper investigates ways to develop better contents. This paper proposes ways to develop learning contents that can increase learners' interest in learning and lead to academic achievement, because the methods of education in Korea are limited to textbook learning and learning through the media. Because of the structure of fairytales and the educational lessons that can be learned from them, Korean learning contents are developed using fairytales. Additionally, Korean contents are designed to implement augmented reality technology, and learners need only have computers, webcams, and markers to make use of it. In consideration of Korean learners who do not have access to augmented reality technology, this paper clarifies that there should be a harmony between existing and new Korean learning contents. On the basis of this study, further studies on Korean education exploring the role of augmented reality should be conducted so that Korean learning contents that use diverse types of augmented reality technology can be will developed.

• Journal of KIISE:Databases
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• v.33 no.4
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• pp.396-408
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• 2006

Moving object databases manage a large amount of past location data which are accumulated as the time goes. To retrieve fast the past location of moving objects, we need index structures which consider features of moving objects. The KDB-tree has a good performance in processing range queries. Although we use the KDB-tree as an index structure for moving object databases, there has an over-split problem in the spatial domain since the feature of moving object databases is to increase the time domain. Because the over-split problem reduces spatial regions in the MBR of nodes inverse proportion to the number of splits, there has a problem that the cost for processing spatial-temporal range queries is increased. In this paper, we propose the dynamic split strategy of the KDB-tree to process efficiently the spatial-temporal range queries. The dynamic split strategy uses the space priority splitting method for choosing the split domain, the recent time splitting policy for splitting a point page to maximize the space utilization, and the last division policy for splitting a region page. We compare the performance of proposed dynamic split strategy with the 3DR-tree, the MV3R-tree, and the KDB-tree. In our performance study for range queries, the number of node access in the MKDB-tree is average 30% less than compared index structures.

• Journal of Convergence for Information Technology
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• v.10 no.2
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• pp.70-81
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• 2020

Living in the modern world, we can easily access large marts and outlets, and live convenient mobile shopping and same-day and early morning shipping. It is called 'shopping addiction' when the purpose of such shopping is not to be attributed to the original purpose of the goods, but to be purchased by an irresistible impulse. According to past studies, 5.8% of American adults and 15.5% of Korean college students were found to be purchase poisoning[3]. The study identified the relationship between interpersonal anxiety, public-consciousness and self-control among the various factors leading to purchase addiction and confirmed their impact on consumers internal psychology. The study found that although Interpersonal anxiety did not directly affect purchasing addiction, it was influenced by self-control and public-consciousness that increased the tendency to purchase addiction. The results of the group comparison between men and women showed that the self-control of men and the public-consciousness of women has increased their purchasing addiction. Such differences in psychology between men and women suggested related implications, such as the need to apply purchase addiction prevention management and treatment methods differently.