• The Journal of Society for e-Business Studies
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• v.15 no.4
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• pp.21-31
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• 2010

Recently e-business such as online financial trade and online shopping using mobile computes are widely spread. Most of mobile computers use NAND flash memory-based storage devices for storing data. Flash memory storage devices use a software called flash translation layer to translate logical address from a file system to physical address of flash memory by using mapping tables. The legacy FTLs have a problem that they must maintain very large mapping tables in the RAM. In order to address this issues, in this paper, we proposed a new caching scheme of mapping tables. We showed through the trace-driven simulations that the proposed caching scheme reduces the space overhead dramatically but does not increase the time overhead. In the case of online transaction workload in e-business environment, in particular, the proposed scheme manifests better performance in reducing the space overhead.

• Journal of the Korean Home Economics Association
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• v.43 no.11 s.213
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• pp.141-152
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• 2005

The purpose of this study was to investigate the actual state of Korean 'geese mothers' in New Zealand. The analysis was peformed for 66 Korean mothers, who had moved temporarily to New Zealand for their children's education. The data have been analyzed by frequencies, percentiles and content analysis. The summarized results of this study are as follows. Most of the mothers were living in New Zealand temporarily for one to three years with one or two children. They hoped that their children will gain better and wide-spread opportunities because of studying abroad. The mothers expected their children to become well prepared as internationalized persons, able to achieve a satisfying occupation with high standard abilities. New Zealand's education system and their migration were highly satisfactory in the mothers' opinions. Most of the them contacted with their husbands who remained in Korea, through e-mails and phone calls, at least once in a week. Most of their friends were Koreans. They listed differences of language, mental values, and personalities as the reasons for having a larger number of Korean friends. The communication with the friends in New Zealand were being done by phones and e-mails mainly. Although there are difficulties for them to communicate others in English, they preferred to enjoy leisure time outside other rather than stay in house. And they gave themselves positive rates on adapting to the new environment, New Zealand.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.2
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• pp.183-193
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• 2013

The characteristics of dental treatment makes the dental staff frequently contact with patient directly. Also the daily use of high-handpieces, sharp instruments, and needles often causes bleeding on oral cavity. Therefore, the risk of cross transmission grows up. The pathogen from dental practice could spread on not only the practice itself but also the dental laboratory with contaminated impressions and prosthesis. Dental clinic staffs (dentists, dental hygienists and dental technicians) should recognize all the patients have a possibility of cross contamination, and try to prevent the transmission of infection by proper infection control. In this study, we review the articles about disinfection methods and chemical infection agents used for dental impressions, and try to figure out the suitable and effective infection control system of dental impressions.

• Journal of the Korean Geographical Society
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• v.51 no.3
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• pp.345-365
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• 2016

This paper is a research that investigated the distribution and status of coastal sand dunes spread along the shoreline of Ongjin-gun, Jung-gu in Incheon and evaluated their conservation status. In Incheon, the length of coastline along the West Sea shoreline is 1,053km. thus leading to an assumption that coastal sand dunes are dispersed their as many as other regional local government. However, there are no enough basic data on the distribution, characteristics, and the management status of other areas besides the 5 places on the list by the Ministry of Environment. Considering this fact, this paper additionally drew 21 coastal sand dunes in the shoreline of Incheon, including the 5 places on the list by the Ministry of Environment, through the standard of coastal sandhill selection. The additionally selected aimed to propose how to develop basic materials on the conservation status of coastal sandhills in Incheon through characteristic analysis by sandhill and qualitative evaluation.

• Journal of Navigation and Port Research
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• v.34 no.3
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• pp.181-187
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• 2010

The performance of underwater wireless communication system is influenced on channel characteristic. Especially, a delay spread cause by reverberation and multi-path happen the ISI (Inter Symbol Interference) and reduces the communication performance. In this paper, we study the application of high speed data transmission in underwater to use the OFDM (Orthogonal Frequency Division Multiplexing) technique for robust the reverberation and multi-path. we confirm the performance of communication in underwater to use the model for actually underwater channel simulation model. As a result, we acquired the BER of modulation techniques. The BER of single carrier is $2{\times}10^{-1}$ and BER of multi carrier is $8{\times}10^{-2}$ in 1000m.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.512-522
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• 2005

In this paper, an optimal determination method of the subband-frame size and mode-switching level is proposed for adaptive OFDM-TDD systems in frequency-selective time-varying channels. The optimization problem considering frequency selectivity. user's mobility, and the signaling overhead caused by the mode change information is formulated in the maximum spectral efficiency sense satisfying the target BER. Assuming that subband-frame size is given, the mode-switching level is first optimized so that the spectral efficiency can be maximized satisfying the target BER. The subband-frame size among candidates is then determined, which maximizes the spectral efficiency. Simulation results show that the proposed scheme outperforms conventional schemes, in terms of the spectral efficiency and the BER.

• Convergence Security Journal
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• v.10 no.1
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• pp.9-17
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• 2010

Internet network routing system is used to prevent spread and distribution of malicious data traffic. The penetration of malicious code and the function of security blocking are performed on the same course of traffic pathway. The security architecture is the concept to distinguish the architecture from the group handling with the traffic on the structure of network which is performed with the function of penetration and security. The security architecture could be different from the criterion of its realm and function, which requires the development and the application of security mechanism for every architecture. For the establishment of security architecture it is needed to show what criterion of net work should be set up. This study is based on analysis of diagnostic weakness structure in the network security architecture and research the criterion for topology factor, security architecture structure map selection, and blocking location and disinfection net. It is shown to increase the effective rate blocking the virus with the proposed method in this paper rather than the traditional network architecture.

• Convergence Security Journal
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• v.8 no.4
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• pp.173-181
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• 2008

Recently, Worm epidemic models have been developed in response to the cyber threats posed by worms in order to analyze their propagation and predict their spread. Some of the most important ones involve mathematical model techniques such as Epidemic(SI), KM (Kermack-MeKendrick), Two-Factor and AAWP(Analytical Active Worm Propagation). However, most models have several inherent limitations. For instance, they target worms that employ random scanning in the network such as CodeRed worm and it was able to be applied to the specified threats. Therefore, we propose the probabilistic of worm propagation based on the Markov Chain, which can be applied to cyber threats such as Mass SQL Injection worm. Using the proposed method in this paper, we can predict the occurrence probability and occurrence frequency for each threats in the entire system.

• Journal of Digital Contents Society
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• v.18 no.8
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• pp.1585-1591
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• 2017

In this study, we propose the application of exhibition contents using virtual environment technology in exhibition space. Research on the virtual environment is continuing. Particularly, research on virtual reality technology is one of the most active research fields. As researches and developments of augmented reality technologies have been carried out with the spread of smart phones, researches on virtual reality technologies have also made a lot of progress with emphasis on games and interactivity. Especially, development of hardware, software, and content is accelerating this year, including the development of various types of physical reality devices, especially HMD (Head Mounted Device) equipment and new product announcements. We want to study and apply the environment in which the system based on this virtual reality technology can approach and experience more user friendly in the exhibition space.

• Journal of the Ergonomics Society of Korea
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• v.33 no.1
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• pp.15-25
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• 2014

Objective: This study aims to analyze the factors that affect the ability to maintain dynamic sitting balance (DSB), biomechanical characteristics, and physical characteristics in spinal cord injuries (SCI) patients. Background: Virtual ski training systems, ski equipment, and training protocols for disabled skiers are being studied to spread awareness. However, few studies have been reported on the sitting balance ability associated with chair mono skiing. Method: A dynamic sitting balance border system was built to investigate the ability to maintain dynamic sitting balance in SCI patients. Trunk muscle activity was evaluated by electromyogram while conducting dynamic sitting balance tests. The trunk muscle strength was tested with a portable handheld dynamometer. Physical activity scores were measured with the physical activity recall assessment. Results: There were high levels of correlation between the ability to maintain DSB and trunk flexor strength, extensor strength, rotator strength, and physical activity score. However, height, weight, and injury level in SCI patients were not correlated with the ability to maintain DSB. Additionally, strong negative correlations were found between muscle activities of the external oblique and lumbar erector spinae muscles and the ability to perform the backward tilt test. Trunk extensor muscle activity during the ball lifting test was significantly higher than in other tests. Conclusion: The results indicate that improving trunk muscle strength and physical activity can increase the ability to maintain DSB. Application: The findings of a close relationship between trunk strength, physical activity, and the ability to maintain DSB need to be reflected in the chair mono ski training program.