• Journal of KIISE:Computing Practices and Letters
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• v.14 no.8
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• pp.758-762
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• 2008

Embedded systems usually utilize Flash Memories with very nice characteristics of non-volatility, low access time, low power and so on. For the multimedia database systems, R-tree is an indexing tree with nice characteristics for multimedia access. MR-tree, which is an upgraded version of R-tree, has shown better performance in searching, inserting and deleting operations than R-tree. Flash memory has sectors and blocks as a unit of read, write and delete operations. Especially, the delete is done on a unit of 512 byte blocks with very large operation time and it is also known that read and write operations on a unit of block matches caching nature of MT-tree. Our research optimizes MR-tree operations in a unit of Flash memory blocks. Such an adjusting leads in better indexing performance in database accesses. With MR-tree on a 512B block units we achieved fast search time of database indexing with low height of MR-tree as well as faster update time of database indexing with the best fit of flash memory blocks. Thus MR-tree with optimized operations shows good characteristics to be a database index schemes on any systems with flash memory.

• Journal of Labour Economics
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• v.27 no.1
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• pp.77-105
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• 2004

Given the limitations of UI benefit and self-insurance through precautionary savings, this paper suggests a new scheme of income support for the unemployed, which offers unemployed workers not only UI benefit but also borrowings from their future pension incomes. Allowing individuals to have effective self-insurance through pension- borrowing, this scheme provides them with consumption-smoothing and reduction in risk burden while maintaining search incentives of the unemployed. Simulation study based upon household panel data in Korea suggests that a heavy reliance should be set upon self-insurance through pension-borrowings rather than upon UI benefit, even for the low-income individuals who are subsidized under UI system. This result provides us with insightful implications for a social safety net in (fast-growing) developing countries, where people cannot afford a good amount of UI benefit or of precautionary savings against unemployment although they expect their incomes to be much higher in the future. Indeed, it is consumption-smoothing effect of self-insurance through pension- borrowings, as well as its incentive-maintaining effect, that makes it a promising alternative of social safety net in developing countries.

• The Journal of the Acoustical Society of Korea
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• v.18 no.2
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• pp.3-10
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• 1999

This paper describes the development and evaluation of a Korean address input system employing automatic speech recognition technique as user interface for input Korean address. Address consists of cities, provinces and counties. The system works on a window 95 environment of personal computer with built-in soundcard. In the speech recognition part, the Continuous density Hidden Markov Model(CHMM) for making phoneme like units(PLUs) and One Pass Dynamic Programming(OPDP) algorithm is used for recognition. For address recognition, Finite State Automata(FSA) suitable for Korean address structure is constructed. To achieve an acceptable performance against the variation of speakers, microphones, and environmental noises, Maximum a posteriori(MAP) estimation is implemented in adaptation. And to improve the recognition speed, fast search method using variable pruning threshold is newly proposed. In the evaluation tests conducted for the 100 connected words uttered by 3 males the system showed above average 96.0% of recognition accuracy for connected words after adaption and recognition speed within 2 seconds, showing the effectiveness of the system.

• Journal of Digital Contents Society
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• v.13 no.4
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• pp.559-565
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• 2012

The remarkable development of IT is contributed to popularization of smart phones, which in turn creates a new domain called app store. Smartphone apps have grown fast because they can be easily purchased through an app store. As the volume of apps traded in app stores is so huge that it is extremely hard for users to find the exact app they want. In general, an app store recommends an app to users based on the search words they entered. In terms of recommendation of app, this kind of content-based method is not effective. To increase accuracy in recommending app, this paper proposes a characteristic similarity-based app recommendation method. This method creates attributes on the app based on the related information such as genre, functionality and number of downloads and then compares them with the propensity to use the app. According to diverse simulations, the method proposed in this paper improved the performance of app recommendation by 33% in average, compared to the conventional method.

• The Journal of Korean Association of Computer Education
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• v.8 no.3
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• pp.77-89
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• 2005

Design of a new information technology curriculum is very difficult work. It has relatively short history of operation. It advances very fast. Furthermore, people have very different understandings between information application and information knowledge. Therefore making decision for information technology contents is very difficult work. So we try to get effectiveness of the curriculum design through the comparison with other countries' cases. In this paper we tried to search and analyze about the historical trends, current states, and characteristics of Chinese information technology curriculum. China has strong focus on information technology education while she makes great success in economic development. We also suggested some good points of Chinese information technology curriculum which can be adapted to the design of a new Korean computer curriculum. The China's information technology curriculum is summarized by four categories. They are (1) educations on the basic knowledges and functions of the stable level of information technology, (2) educations on the information technology applications for the problem solving, (3) educations for the individualized learning through the research and project implementations in depth, and (4) systematic arrangements and integrated operations of the information technology curriculum.

• The KIPS Transactions:PartA
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• v.10A no.5
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• pp.453-462
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• 2003

IP address lookup of router searches and decide proper output link using destination address of IP packet that arrie into router. The IP address lookup is essential part in te development of high-speed router needed to high-speed backbone network as one of bottleneck of router performance. This paper introduces DTC data structure that can support gigabit IP address lookup by dynamic trie compression technique that just uses small memory in conventional Pentium CPU. When make a forwarding table by trie compression, the DTC can dynamically select a size of data structure with considering correlation between table's size and searching speed. Also, when compress the prefix trie, DTC makes IP address lookup on the forwarding table of a search on the high speed SRAM cache by minimizing the size of data structure reflecting the structure of the trie. In the experiment result, the DTC data structure recorded performance of maximum $12.5{\times}10^5$ LPS (lookup per second) in conventional Pentium CPU through a dynamic building of most suitable compression over variety of routing tables.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.158-166
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• 2004

Address lookup is one of the most essential functions of the Internet routers and a very important feature in evaluating router performance. Due to the facts that the Internet traffic keeps growing and the number of routing table entries is continuously growing, efficient address-lookup mechanism is indispensable. In recent years, various fast address-lookup schemes have been proposed, but most of those schemes are not practical in terms of the memory size required for routing table and the complexity required in table update In this paper, we have proposed a parallel IP address lookup architecture based on multiple hashing. The proposed scheme has advantages in required memory size, the number of memory accesses, and table update. We have evaluated the performance of the proposed scheme through simulation using data from MAE-WEST router. The simulation result shows that the proposed scheme requires a single memory access for the address lookup of each route when 203kbytes of memory and a few-hundred-entry TCAM are used.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.5
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• pp.137-144
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• 1989

A new algorithm is presented which efficiently reports minimum width/space violation in a geometric mask pattern. The proposed algorithm solves a sequence of range search problems by employing a plane sweep method. The algorithm runs in O(n log n) time, where n is the number of edges in a mask pattern. Since a lower bound in time conplexity for reporting all minimum width/space violations is ${\Omega}$ (n log n), this algorithm is theoretically optimal within a constant multiplicaive factor. It requires O($n^{0.5}$) space which is very efficient in practice. Moreover, this algorithm, we believe, is easy to implement and practically fast (116.7 seconds for a rectilinear region with 250000 vertices ar VAX 8650.)

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.81-87
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• 1999

In general, feature detection and tracking algorithms is classified by EBGM using Garbor-jet, NNC-R and STK algorithm using pixel eigenvalue. In those algorithms, EBGM and NCC-R detect features with feature model, but STK algorithm has a characteristics of an automatic feature selection. In this paper, to solve the initial problem of NR tracking in STK algorithm, we detected features using STK algorithm in modelled feature region and tracked features with NR method. In tracking, to improve the tracking accuracy for features by NR method, we proposed BMA-NR method. We evaluated that BMA-NR method was superior to NBMA-NR in that feature tracking accuracy, since BMA-NR method was able to solve the local minimum problem due to search window size of NR.

• Journal of Internet Computing and Services
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• v.15 no.6
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• pp.117-124
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• 2014

Cluttered background is a major obstacle in developing salient object detection and tracking system for mobile device captured natural scene video frames. In this paper we propose a context aware feature vector selection model to provide an efficient noise filtering by machine learning based classifiers. Since the context awareness for feature selection is achieved by searching nearest neighborhoods, known as NP hard problem, we apply a fast approximation method with complexity analysis in details. Separability enhancement in feature vector space by adding the context aware feature subsets is studied rigorously using principal component analysis (PCA). Overall performance enhancement is quantified by the statistical measures in terms of the various machine learning models including MLP, SVM, Naïve Bayesian, CART. Summary of computational costs and performance enhancement is also presented.