• Ocean Systems Engineering
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• v.10 no.2
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• pp.201-226
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• 2020

A systematic numerical comparative study of the performance of semicircular and rectangular submerged breakwaters interacting with solitary waves is the basis of this paper. To accomplish this task, Nwogu's extended Boussinesq model equations are employed to simulate the interaction of the wave with breakwaters. The finite difference technique has been used to discretize the spatial terms while a fourth-order predictor-corrector method is employed for time discretization in our numerical model. The proposed computational scheme uses a staggered-grid system where the first-order spatial derivatives have been discretized with fourth-order accuracy. For validation purposes, five test cases are considered and numerical results have been successfully compared with the existing analytical and experimental results. The performances of the rectangular and semicircular breakwaters have been examined in terms of the wave reflection, transmission, and dissipation coefficients (RTD coefficients) denoted by K_R, K_T, K_D. The latter coefficient K_D emerges due to the non-energy conserving K_R and K_T. Our computational results and graphical illustrations show that the rectangular breakwater has higher reflection coefficients than semicircular breakwater for a fixed crest height, but as the wave height increases, the two reflection coefficients approach each other. un the other hand, the rectangular breakwater has larger dissipation coefficients compared to that of the semicircular breakwater and the difference between them increases as the height of the crest increases. However, the transmission coefficient for the semicircular breakwater is greater than that of the rectangular breakwater and the difference in their transmission coefficients increases with the crest height. Quantitatively, for rectangular breakwaters the reflection coefficients K_R are 5-15% higher while the diffusion coefficients K_D are 3-23% higher than that for the semicircular breakwaters, respectively. The transmission coefficients K_T for rectangular breakwater shows the better performance up to 2.47% than that for the semicircular breakwaters. Based on our computational results, one may conclude that the rectangular breakwater has a better overall performance than the semicircular breakwater. Although the model equations are non-dissipative, the non-energy conserving transmission and reflection coefficients due to wave-breakwater interactions lead to dissipation type contribution.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.7
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• pp.177-186
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• 2012

Social Network Service is a web-based service that allows the people to construct relationship among users with same interest and supports various activities such as managing personal relations and sharing information or contents. The objective of this study is analysing the influence of the innovativeness on the use intention in SNS based on the UTAUT model. This study establishes a theoretical model that includes four independent variables(performance expectancy, effort expendancy, social influence, innovativeness) and two moderating variables(gender and innovativeness). The empirical results obtained in a sample of 403 university students are followings; 1) The use intention is positively influenced by the performance expectancy, effort expendancy, social influence and innovativeness. The effort expectancy is the strongest predictor of the use intention 2) The gender has a moderating effect whileas the innovativeness has no moderating effect. For men, the stronger the effect of performance expectancy on the use intention and for women, the stronger the effect of social influence on the use intention.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9C
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• pp.891-897
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• 2003

Partial response maxim likelihood (PRML) is a powerful and indispensable detection scheme for perpendicular magnetic recording channels. The performance of PRML can be improved by incorporating a noise prediction scheme into branch metric computations of Viterbi algorithm (VA). However, the systems constructed by VA have shortcomings in the form of high complexity and cost. In this connection, a new simple detection scheme is proposed by exploiting the minimum run-length parameter d=1 of RLL code. The proposed detection scheme have a slicer instead of Viterbi detector and a noise predictor as a feedback filter. Therefore, to improve BER performance, the proposed detection scheme is extended to dual detection scheme for improving the BER performance. Simulation results show that the proposed scheme has a comparable performance to noise-predictive maximum likelihood (NPML) detector with less complexity when the partial response (PR) target is (1,2,1).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.7
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• pp.47-52
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• 2009

H.264 video coding standard is widely used due to the high compression rate and quality. The motion compensation is the most time-consuming and complex unit in the H.264 decoder. The performance of the motion compensation is determined by the calculation of pixel interpolation and management of the reference pixels. The reference pixels read from external memory using efficient memory management for data reuse is necessary along with the high performance interpolators. We propose the architecture of a motion compensation unit for H.264 decoders. It is composed of 2-dimensional circular register files, a motion vector predictor and high performance interpolators with low complexity. The 2-dimensional circular register files reuse reference pixel data as much as possible, and feed reference pixel data to interpolators without any latency and complex logic circuits. We design a motion compensation unit and a intra-prediction unit and integrate them into a prediction unit and verify the operation and the performance.

• Journal of Korea Game Society
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• v.12 no.2
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• pp.15-29
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• 2012

In order to predict satisfaction and performance of sensible healthcare game using motion recognition sensor, this study analyzed the effects of flow, presence and social cognitive factor and then, it attempted to verify structural relationships thereof. Self-efficacy, being a social cognitive factor, was found to affect the level of functional satisfaction of health game but it showed no direct effect to intention of using game. Flow experience was also observed to be a meaningful predictor for the level of functional and entertainment satisfaction in the direction hypothesized. It is also shown that presence exerts a direct effect on functional satisfaction. Finally, it is discovered that functional satisfaction has meaningful influence on entertainment satisfaction as well as future intention to use. The results verifies that even in sensible healthcare game, user experience and social cognitive factor have significant effects on satisfaction and performance of a serious game.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6242-6249
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• 2014

The aim of this study was to determine the physical performance and fear of falls in the community dwelling elderly and to investigate how the factors were connected to one another. The data was collected between January 3rd and March 30th, 2014 from 460 elderly people, aged 65 or older, who agreed to participate in this study. The data was sampled among the elders' assistants as a way of responding to the questionnaire after being read. The study scales were composed of the demographic characteristics, physical function and fear of falls. A total of 139 (30.2%) subjects had experienced a fall. The results showed a positive correlation with the chair rise, standing on the leg, pick up a penny from floor, timed up and go test, and fear of falls. Multiple linear regression analysis showed that a predictor of the fear of falls were chair rise and timed up and go test. A combination of physical performance accounted for 16.9% of the fear of fall. Based on the findings of this study, it is useful to more effectively develop fall prevention and intervention programs in a future study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1100-1108
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• 2013

This study analyzes the relationship between teachers' efficacy and difficulties on job performance depended on self-esteem. To achieve this goal, 282 child care teachers who inhabit J city responded to the questionnaire. The collected data were analyzed by Pearson correlation and multiple regression techniques using the SPSS statistics program. First, the self-esteem was closely associated with child care teachers' efficacy and difficulties on job performance. Second, the self-esteem was the strongest predictor for general teaching efficacy of child care teacher and Infant's protection and guidance also notable variables. This significant result shows the importance of self-esteem. Therefore, it is desirable to encourage child care teachers to experience and raise self-esteem.

• Journal of Broadcast Engineering
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• v.24 no.3
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• pp.401-410
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• 2019

In this paper, we propose a reference picture generation method for Inter-layer prediction based deep learning to improve the SHVC coding performance. A description will be given of a structure for performing filtering using a VDSR network on a DCT-IF based upsampled picture to generate a new reference picture and a training method for generating a reference picture between SHVC Inter-layer. The proposed method is implemented based on SHM 12.0. In order to evaluate the performance, we compare the method of generating Inter-layer predictor by applying dictionary learning. As a result, the coding performance of the enhancement layer showed a bitrate reduction of up to 13.14% compared to the method using dictionary learning, a bitrate reduction of up to 15.39% compared to SHM, and a bitrate reduction of 6.46% on average.

• Safety and Health at Work
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• v.10 no.1
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• pp.54-60
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• 2019

Background: Increasing the establishment of integrated management systems (IMSs) is done with the purpose of leaving traditional management methods and replacing them with modern management methods. Thus, the present study sought to analyze the events and investigate the impact of IMS on health and safety performance indices in an Iranian combined cycle power plants. Methods: This case study was conducted in 2012 in all units of the Yazd Combined Cycle Power Plant on accident victims before and after the implementation of IMS. For data analysis and prediction of indices after the implementation of IMS, descriptive statistics and Kolmogorov-Smirnov test, Chi-square, linear regression, and Cubic tests were conducted using SPSS software. Results: The number of people employed in the power plant in an 8-year period (2004-2011) was 1,189, and 287 cases of work-related accidents were recorded. The highest accident frequency rate and accident severity rate were in 2004 (32.65) and 2008 (209), respectively. Safe T-score reached to below -3 during 2010-2011. In addition, given the regression results, the relation between all predictor variables with outcomes was significant (p < 0.05), except for the variable $X^1$ belonging to the accident severity rate index. Conclusion: The implementation of safety programs especially that of IMS and its annual audits has had a significant impact on reducing accident indices and improving safety within the study period. Accordingly, health and safety management systems are appropriate tools for reducing accident rate, and the use of regression models and accident indices is also a suitable way for monitoring safety performance.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.24-35
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• 2012

In this paper, we propose a dynamic lane control scheme with a traffic predictor module and a rate controller for reconciling with commercial optical PHY modules in energy efficient optical Ethernet systems. The commercial high speed optical Ethernet system capable of 40/100Gbps employs 4 or 10 multiple optical transceivers over WDM or multiple optical links. Each of the transceivers is always turned on even if the link is idle. To save energy, we propose the dynamic lane control scheme. It allows that several links may be entirely turned off in a low traffic load and frames are handled on the remaining active links. To preserve the byte order even if the number of active links may be changed, we propose a rate controller to be sat on the reconciliation sublayer. The main role of the controller is to insert null byte streams into the xGMII of inactive lanes. For the PHY module, the null input streams corresponding to inactive lanes will be disregarded on inactive PMDs. It is very handy to implement the rate controller module with MAC in FPGA without any modification of commercial PHYs. It is very crucial to determine the number of active links based on the fluctuated traffic load, we provide a simple traffic predictor based on both the current transmission buffer size and the past one with different weighting factors for adapting to the traffic load fluctuation. Using the OMNET++ simulation framework, we provide several performance results in terms of the energy consumption.