• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.13-22
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• 2005

This paper aims to develop a system for converting web contents to mobile contents that can be used on mobile devices. Since web contents generally consist of pop-up ad windows, a bunch of unnecessary images and useless links, it is difficult to efficiently display them on common mobile devices that have lower bandwidth and memory, as well as much smaller screen, than the online environment. It is also troublesome for mobile device users to directly access contents. Thus, there has been a great demand for a new method for extracting useful and adequate contents from web documents, and optimizing them for use on mobile phones, In the paper, a system based on WAP 2,0 and XHTML Basic, which is a content creation language adopted for WAP 2,0, has been suggested. The system is designed to convert web contents by using the conversion rules of the existing filtering method after making the size of web documents smaller. The adopted conversion rules use the XHTML Basic's module units so that modification and deletion can be carried out with ease. In addition, it has been defined in a XSL document written in XSLT to maintain the extensibility of conversion and the validity of documents, In order to allow it to efficiently work together with WAP l.X's legacy services, the system has been built in a way that can have modules, which analyze information about CC/PP profiles and mobile device headers.

• Korean journal of communication and information
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• v.41
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• pp.303-336
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• 2008

The purpose of this study is to examine the uses and gratifications of the U. S. TV dramas favored by the Korean college students. The uses and gratifications of the U. S. TV dramas are also compared with the Korean TV dramas. In addition, this study analyzes how the motives and satisfactions of students on the U. S. dramas influence on watching patterns of the Korean TV dramas. The results of the factor analysis show that student's motives on watching the U. S. TV dramas are composed of four factors, such as 'Entertainment/Relaxation', 'Getting Information', 'Environment/Companionship', and 'Sexual curiosity'. In contrast, the motives of watching Korean TV dramas are composed of six factors, which are added 'Korean Drama Characteristics' and 'Habitual Time-Spending' to four factors of the U. S. dramas. After dividing the student groups with the heavy and the light watchers, this research shows that three out of five for the U. S. dramas are significantly different, whereas two out of six factors for the Korean counterparts. Finally, the uses and gratifications of the U. S. dramas favored by the Korean college students influence little on the watching patterns of the Korean TV dramas.

• The KIPS Transactions:PartD
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• v.10D no.3
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• pp.407-416
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• 2003

As the usage of database systems dramatically increases and the amount of data pouring into them is massive, the performance administration techniques for using database systems effectively are getting more important. Especially in data warehouses, the performance management is much more significant mainly because of large volume of data and complex queries. The objectives and characteristics of data warehouses are different from those of other operational systems so adequate techniques for performance monitoring and tuning are needed. In this paper we extend functionalities of the DBMax, a performance administration tool for Oracle database systems, to apply it to data warehouse systems. First we analyze requirements based on summary management and ETL functions they are supported for data warehouse performance improvement in Oracle 9i. Then, we design architecture for extending DBMax functionalities and implement it. In specifics, we support SQL tuning by providing details of schema objects for summary management and ETL processes and statistics information. Also we provide new function that advises useful materialized views on workload extracted from DBMax log files and analyze usage of existing materialized views.

• Journal of Korea Spatial Information System Society
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• v.10 no.2
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• pp.81-93
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• 2008

Current re-arrangement of river and waterway has been made uniformly ignoring characteristics of individual rivers thereby aggravating artificial river restructuring. Subsequently this severely affects the rivers' physical, chemical, and biological phenomenon. On the contrary, quantitative techniques to evaluate the aftermath of artificial river disturbance such as uprising of river bed, intrusion of foreign fisheries, and changes of ecological habitats are not available. To establish such quantitative techniques, analysis of river changes to evaluate the major causes of the river disturbance and its impacts is essential. Therefore, this study mainly focused on proposing a method which can be applied for the development of techniques to investigate river disturbance according to the major factors for the domestic rivers using airphotos and GIS techniques. For the analysis, the study area on the downstream of the river was selected and airphotos of the area were converted into GIS format to generate 'shape' files to secure waterways, river banks, and auxiliary data required for analyzing river disturbance. Trend analysis of the waterway sinuosity and changes of the flow path leaded to detailed verification of the river disturbance for specific location or time period, and this enabled to relatively accurate numbers representing sinuosity of the waterway and relevant changes. As the major results from the analysis, the relocation of waterways and the level of river sinuosity were quantified and used to verify the impacts on the stability of the waterways especially in the downstream of the dam. The results from this study enabled effective establishing proper measures against waterways' unstability, and emphasized subsequent researches for identifying better alternatives against river disturbances.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.11
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• pp.403-410
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• 2022

Non-Fungible Tokens (NFTs) created on the basis of blockchain have their own unique value, so they cannot be forged or exchanged with other tokens or coins. Using these characteristics, NFTs can be issued to digital assets such as images, videos, artworks, game characters, and items to claim ownership of digital assets among many users and objects in cyberspace, as well as proving the original. However, interest in NFTs exploded from the beginning of 2020, causing a lot of load on the blockchain network, and as a result, users are experiencing problems such as delays in computational processing or very large fees in the mining process. Additionally, all actions of users are stored in the blockchain, and digital assets are stored in a blockchain-based distributed file storage system, which may unnecessarily expose the personal information of users who do not want to identify themselves on the Internet. In this paper, we propose an NFT platform using cloud computing, access gate, conversion table, and cloud ID to improve usability and privacy problems that occur in existing system. For performance comparison between local and cloud systems, we measured the gas used for smart contract deployment and NFT-issued transaction. As a result, even though the cloud system used the same experimental environment and parameters, it saved about 3.75% of gas for smart contract deployment and about 4.6% for NFT-generated transaction, confirming that the cloud system can handle computations more efficiently than the local system.

• Journal of the Korea Society of Computer and Information
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• v.18 no.4
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• pp.65-77
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• 2013

Recently the ratio of the Internet traffic generated by video streaming applications including video-on-demand (VOD) is getting higher and higher, while P2P-based naive content distribution has been the main source of the Internet traffic in the past. As a result, the paradigm of cooperatively distributed systems (e.g., P2P) is changing to support streaming applications. Most P2P assisted approaches for video streaming today are based on Bit Torrent thanks to its simplicity of implementation and easy adaptability. They, however, have immanent vulnerability to free-riding inherited from Bit Torrent, which inevitably hurts their performance under limited system resources with free-riding. This paper studies the weakness to free-riding of existing Bit Torrent-based video streaming applications and investigates the adaptability of T-Chain (which was originally designed to prevent free-riding in cooperatively distributed systems) to video streaming applications. Our experiment results show that the video streaming approach based on T-Chain outperforms most existing Bit Torrent-based ones by 60% on average under limited system resources with free-riding.

• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.399-408
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• 2008

Mobile WiMAX provides wireless broadband services for data communication based on IP protocol. The limitation of physical bandwidth in the radio links may cause performance degradation in providing wireless broadband services in WIMAX. To enhance the efficiency of the radio link utilization, Payload Header Suppression (PHS) is defined as an optional header compression mechanism for mobile WiMAX. It has, however, a very limited compression capability since it has very restrictive compression fields. In this paper, hence, we assumed the application of Robust Header Compression (ROHC), a header compression scheme proposed for links characterized by high bit error ratios, long round-trip times (RTT), and scarce resource, to Mobile WiMAX, and studied its performance. Previous studies on ROHC performance merely focused on the impact of high bit error rate. However, bit error is virtually transparent to ROHC in the wireless systems like WiMAX, since the MAC provides the bit error checking function. In order to evaluate the performance of ROHC in the Mobile WiMAX environments, therefore, we evaluated the performance of ROHC with respect to the packet losses instead of bit error. We investigated the impact of the ROHC parameters that are recommended for the implementation in the ROHC and compared the performance of ROHC with PHS.

• The KIPS Transactions:PartD
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• v.13D no.4 s.107
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• pp.549-556
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• 2006

In this paper, we propose a system for generating skeleton programs for directly transforming an XML document to another document, whose structure is defined in the target DTD with GUI environment. With the generated code, the users can easily update or insert their own codes into the program so that they can convert the document as the way that they want and can be connected with other classes or library files. Since most of the currently available code generation systems or methods for transforming XML documents use XSLT or XQuery, it is very difficult or impossible for users to manipulate the source code for further updates or refinements. As the generated code in this paper reveals the code along the XPaths of the target DTD, the result code is quite readable. The code generating procedure is simple; once the user maps the related elements represented as trees in the GUI interface, the source document is transformed into the target document and its corresponding Java source program is generated, where DTD is given or extracted from XML documents automatically by parsing it. The mapping is classified 1:1, 1:N, and N:1, according to the structure and semantics of elements of the DTD. The functions for changing the structure of elements designated by the user are amalgamated into the metadata interface. A real world example of transforming articles written in XML file into a bibliographical XML document is shown with the transformed result and its code.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.389-395
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• 2015

Digital image provides many conveniences at the internet environment recently. A great number of applications, like Digital Library, Stock Image, Personal Image and Important Information, require the use of digital image. However it has fatal defect which is easy to be modified because digital image is only electronic file. Numerous digital image forgeries have become a serious problem due to the sophistication and accessibility of image editing software. Copy-Move forgery is the simplest type of forgery that involves copying portion of an image and paste it on different location within the image. There are many approaches to detect Copy-Move forgery, but all of them have their own limitations. In this paper, visual and invisible feature based forgery detection techniques are tested and analyzed. The analysis shows that pros and cons of these two techniques compensate each other. Therefore, a hybrid of visual based and invisible feature based forgery detection that combine the merits of both techniques is proposed. The experimental results show that the proposed algorithm has enhanced performance compared to individual techniques. Moreover, it provides more information about the forgery, like identifying copy and duplicate regions.

• The KIPS Transactions:PartA
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• v.13A no.7 s.104
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• pp.615-622
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• 2006

Caching in a Wireless Internet Proxy Server Cluster Environment has an effect that minimizes the time on the request and response of Internet traffic and Web user As a way to increase the hit ratio of cache, we can use a hash function to make the same request URLs to be assigned to the same cache server. The disadvantage of the hashing scheme is that client requests cannot be well-distributed to all cache servers so that the performance of the whole system can depend on only a few busy servers. In this paper, we propose an improved load balancing scheme using hashing and Round Robin scheme that distributes client requests evenly to cache servers. In the existing hashing scheme, if a hashing value for a request URL is calculated, the server number is statically fixed at compile time while in the proposed scheme it is dynamically fixed at run time using round robin method. We implemented the proposed scheme in a Wireless Internet Proxy Server Cluster Environment and performed experiments using 16 PCs. Experimental results show the even distribution of client requests and the 52% to 112% performance improvement compared to the existing hashing method.