• KIISE Transactions on Computing Practices
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• v.23 no.8
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• pp.510-515
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• 2017

It is important to speed up the loading time of web applications. Parsing is a loading process that contributes to an increased loading time. To address this issue, the optimization called Concurrent Parsing has been proposed which handles the parsing process in parallel by using additional threads. However, Concurrent Parsing has a limitation that it does not consider the priority order of parsing. In this paper, we propose heuristics that exploit priorities of parsing to improve the Concurrent Parsing. For parsing priority, we empirically investigate the sequence of function calls, classify functions into 3 categories, and extract function call probabilities. If a function has high call probability, we give a high priority and if a function has low probability, we give a low priority. We evaluate this priority heuristics on real web applications and get the 2.6% decrease of loading time on average.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.5
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• pp.513-518
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• 2010

The advancement of information technology along with the proliferation of communication and multimedia has increased the demand of digital contents. Video data of digital contents such as VOD, NOD, Digital Library, IPTV, and UCC are getting more permeated in various application fields. Video data have sequential characteristic besides providing the spatial and temporal information in its 3D format, making searching or browsing ineffective due to long turnaround time. In this paper, we suggest ATVC(Authoring Tool for Video Contents) for solving this issue. ATVC is a video editing tool that detects key frames using visual rhythm and insert metadata such as keywords into key frames via XML tagging. Visual rhythm is applied to map 3D spatial and temporal information to 2D information. Its processing speed is fast because it can get pixel information without IDCT, and it can classify edit-effects such as cut, wipe, and dissolve. Since XML data save key frame information via XML tag and keyword information, it can furnish efficient browsing.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.586-588
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• 2007

The Moore's law states that the number of transistors on a chip doubles about every 18 months. And it was reported that the network speed has been doubled about every 9 months. This indicates that computing power and network is no longer the obstacles for the high performance applications requiring terabits networks. We believe that the application motivates the network and vice versa. This presentation will introduce the GLORIAD which is the first ring network connecting six countries around the world and provides scientists with advanced networking tools that improve a communications and data exchange. The GLORIAD trans-Pacific link started its service on August 1, 2005. Since then, there has been remarkable demonstrations were performed through major conferences like Supercomputing Conference. This paper will introduce the global collaborative works on demonstrations of VMT, high energy physics, SDSS and HD video transmission during SC'06 in Tampa, FL.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.2
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• pp.110-118
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• 2007

Due to the development of high speed Internet, a number of Internet users connect online to access web sites. However, there are several procedures required, before you actually find what you were looking for. These procedures are necessary to access Internet services you need, but it is somewhat inconvenient to users. The virtual portal system suggested in this paper is designed to solve such inconvenience. The virtual portal system described in this paper perceives personal computers as web service providing sites, so that it enables users to define customized services by themselves. Also, it makes an exclusive browser as a multiple browser window and provides features to navigate web sites. Therefore, this paper suggests methods for building a pesonalized virtual portal system, where users are able to access web services more conveniently.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.5
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• pp.322-330
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• 2009

In order to utilize NAND flash memory as storage media which does not allow update-in-place and limits the number of block erase count, various garbage collection policies supporting wear-leveling have been investigated. Conventional garbage collection policies require cleaning-index calculation for the entire blocks to choose a block to be garbage-collected to support wear-leveling whenever a garbage collection is required, which results in performance degradation of system. This paper proposes a garbage collection policy which supports wear-leveling using a threshold value, which is in fact a variance of erase counts and by the maximum erase count of all blocks, without calculating the cleaning-index. During garbage collection, the erase cost is minimized by using the Greedy Policy if the variance is less than the threshold value. It achieves wear-leveling by excluding the block with the largest erase count from erase target blocks if the variance is larger than threshold value. The proposed scheme shows that a standard deviation approaches to zero as the erase count of blocks approaches to its upper limit and the measured speed of garbage collection is two times faster than the conventional schemes.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.1
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• pp.62-66
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• 2009

Recently developed compilers perform some optimizations in order to speed up the execution time of source program. These optimizations require the transformation of the sequence of program statements. This transformation does not give any problems in a single-threaded program. However, the transformation gives some significant errors in a multi-threaded program. State-of-the-art model checkers such as Java-Pathfinder do not consider the transformation resulted in the optimization step in a compiler since they just consider a single memory model. In this paper, we describe a new technique which is based on SMT solver. The Java Memory Model Simulator based on SMT Solver can compute all possible output of given multi-thread program within one second which, in contrast, Traditional Java Memory Model Simulator takes one minute.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.4
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• pp.507-511
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• 2010

In this paper, we propose to enhance the performance of software transcoder by using GPGPU for scaling filters. Video transcoding is a technique that translates a video file to another video file that has a different coding algorithm and/or a different frame size. Its demand increases as more multimedia devices with different specification coexist in our daily life. Since transcoding is computationally intensive, a software transcoder that runs on a CPU takes long processing time. In this paper, we achieve significant speed-up by parallelizing the scaling filter using a GPGPU that can provide significantly large computation power. Through extensive experiments with various video scripts of different size and with various scaling filter options, it is verified that the enhanced transcoder could achieve 36% performance improvement in the default option, and up to 101% in a certain option.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.4
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• pp.482-486
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• 2010

Recently, gesture recognition methods based on dynamic time warping (DTW) have been actively investigated as more mobile devices have equipped the accelerometer. DTW has no additional training step since it uses given samples as the matching templates. However, it is difficult to apply the DTW on mobile environments because of its computational complexity of matching step where the input pattern has to be compared with every templates. In order to address the problem, this paper proposes a gesture recognition method based on DTW that uses localized subset of templates. Here, the k-means clustering algorithm is used to divide each class into subclasses in which the most centered sample in each subclass is employed as the localized template. It increases the recognition speed by reducing the number of matches while it minimizes the errors by preserving the diversities of the training patterns. Experimental results showed that the proposed method was about five times faster than the DTW with all training samples, and more stable than the randomly selected templates.

• KIISE Transactions on Computing Practices
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• v.23 no.11
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• pp.617-624
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• 2017

Speech recognition is now one of the most widely used technologies in HCI. Many applications where speech recognition may be used (such as home automation, automatic speech translation, and car navigation) are now under active development. In addition, the demand for speech recognition systems in mobile environments is rapidly increasing. This paper is intended to present a method for instant recognition of the Korean vowel 'ㅡ', as a part of a Korean speech recognition system. The proposed method uses bulk indicators (which are calculated in the time domain) instead of the frequency domain and consequently, the computational cost for the recognition can be reduced. The bulk indicators representing predominant sequence patterns of the vowel 'ㅡ' are learned by neural networks and final recognition decisions are made by those trained neural networks. The results of the experiment show that the proposed method can achieve 88.7% recognition accuracy, and recognition speed of 0.74 msec per syllable.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.884-892
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• 2014

In this paper, a meta model using neural network substituting for the simulator aerodynamic database is proposed to improve simulation fidelity near the critical flight area and real-time performance. It is shown that the accuracy of the meta model is relatively higher than the existing table lookup methods for arbitrary nonlinear database and the calculation speed is also improved for a specific F-16 maneuver simulation. The increase in the number of hidden nodes in the meta model for better accuracy of database representations causes a delay in function generation due to increased time required for computing exponential functions. In order to make up this drawback, we additionally study the fast exponential function method.