• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.9
• /
• pp.2882-2903
• /
• 2022

Image super-resolution (SR) processing is of great value in the fields of digital image processing, intelligent security, film and television production and so on. This paper proposed a densely connected deep learning network based on cascade architecture, which can be used to solve the problem of super-resolution in the field of image quality enhancement. We proposed a more efficient residual scaling dense block (RSDB) and the multi-channel cascade architecture to realize more efficient feature reuse. Also we proposed a hybrid loss function based on L₁ error and L_∞ error to achieve better L_∞ error performance. The experimental results show that the overall performance of the network is effectively improved on cascade architecture and residual scaling. Compared with the residual dense net (RDN), the PSNR / SSIM of the new method is improved by 2.24% / 1.44% respectively, and the L_∞ performance is improved by 3.64%. It shows that the cascade connection and residual scaling method can effectively realize feature reuse, improving the residual convergence speed and learning efficiency of our network. The L_∞ performance is improved by 11.09% with only a minimal loses of 1.14% / 0.60% on PSNR / SSIM performance after adopting the new loss function. That is to say, the L_∞ performance can be improved greatly on the new loss function with a minor loss of PSNR / SSIM performance, which is of great value in L_∞ error sensitive tasks.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.50-62
• /
• 2011

In this paper, analytical techniques for performance characteristics analysis of wind power generator with outer permanent magnet rotor are proposed. Furthermore, the proposed analytical techniques are validated by performance experiments of the manufactured generator. In this part, characteristic equations of losses such as copper loss, core loss are derived. Using the derived loss characteristic equations, electrical parameters obtained in [15] and d-q axes method, constant load and constant speed characteristics of wind power generator are analyzed. And then, to analyze performance of wind power system according to wind speed, d-q analysis model considering wind turbine characteristics is proposed. Finally, the obtained performance characteristics results are validated in comparison with those by experiments.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.10
• /
• pp.1247-1254
• /
• 2004

In momentum exchange theory the loss models for the circulatory flow is critically important. But because of lack of loss model on the circulatory flow, analysis model on regenerative turbomachines is not available in the open literature. In the present study circulatory loss is evaluated by combining bend's losses. Through the comparison with the previous experimental data on linear pressure gradient, a combination factor is suggested in terms of the aspect ratio of a channel. Applying this factor to two kinds of regenerative blowers the predicted results are found to be in good agreement with the experimental data of the overall performance and the head distribution along the rotational direction. Especially, the comparison with the head distribution demonstrates the accuracy of hydraulic model and loss model suggested in the present study. And the comparison with the overall performance confirms the validness of physical models as well as loss models suggested in the present study.

• The Journal of the Acoustical Society of Korea
• /
• v.32 no.5
• /
• pp.415-422
• /
• 2013

This paper proposes a robust binary audio fingerprinting method by minimizing hinge-loss function. In the proposed method, the type of fingerprints is binary, which is conducive in reducing the size of fingerprint DB. In general, the binarization of features for fingerprinting deteriorates the performance of fingerprinting system, such as robustness and discriminability. Thus it is necessary to minimize such performance loss. Since the similarity between two audio clips is represented by a hinge-like function, we propose a method to derive a binary fingerprinting by minimizing a hinge-loss function. The derived hinge-loss function is minimized by using the minimal loss hashing. Experiments over thousands of songs demonstrate that the identification performance of binary fingerprinting can be improved by minimizing the proposed hinge loss function.

• Journal of the Korean Home Economics Association
• /
• v.46 no.10
• /
• pp.71-81
• /
• 2008

This study aimed to identify the effects of adolescents' perceived risk on fashion brand conformity behavior. To analyze conformable fashion brand behavior with consideration to their reference group, 6 dimensions of perceived risk were adopted as explanatory variables. Reference group means people that a person refers to when evaluating his values & behaviors. Data were collected from 672 male and female students aged between 14 and 18. Factor analysis on perceived risk resulted in 6 dimensional structures: socio-psychological, time loss, functional, fashionability loss, performance and opportunity loss risk. Fashionability loss risk positively affected adolescent fashion brand conformity behavior according to their favorite celebrities. Performance risk positively affected in consideration to their parents, while opportunity loss risk had a negative effect on the same reference group. However, socio-psychological and fashionability loss risk positively affected adolescent fashion brand conformity behavior in consideration to their friends, while performance loss risk had negative effect on the same reference group. Adolescent groups divided by the 6 dimensions of perceived risk showed meaningful differences in their fashion brand conformable behavior in consideration to their reference groups.

• Journal of Korea Multimedia Society
• /
• v.16 no.9
• /
• pp.1067-1076
• /
• 2013

Known as an important criterion that evaluates performance of future high-speed backbone networks, burst data loss ratio is well-studied in Optical Burst Switching networks. Current literatures mostly focus on reduce burst loss ratio without considering the system stability and link utilization after reducing. In this paper, we propose a novel framework which comes from feedback theoretic to dynamically control burst loss ratio in OBS. The proposed scheme tries to track the pre-set values of burst loss ratio and increases the stability and link utilization degree. The simulation results show that measured burst loss ratio always tracks setup reference with small errors, wavelength channel utilization is increased up to 2% and the system stability is also improved.

• Journal of Mechanical Science and Technology
• /
• v.18 no.11
• /
• pp.2021-2031
• /
• 2004

A new nondimensional method for predicting the windmilling performance of centrifugal -flow turbojet engines in flight has been developed. The method incorporates loss correlations to estimate the performance of major engine components. Given basic engine geometry, flight Mach number, and ambient conditions, this method predicts transient and steady-state windmilling performance. Thus, this method can be used during the preliminary design stage when detailed hardware geometry and component performance data are not yet available. A nondimensional time parameter is newly defined, and using this parameter, the transient performance of different types of turbojets (e.g. centrifugal vs. axial) is compared. In addition, the predictions' sensitivity to loss correlations, slip factors, and inlet ambient temperatures are analyzed.

• The KSFM Journal of Fluid Machinery
• /
• v.10 no.4
• /
• pp.21-28
• /
• 2007

The ratio of disk friction loss in a centrifugal pump is very large for the total pump loss in the range of very low specific speed. Therefore, impeller radius should be shortened to increase the pump efficiency because the disk friction loss is proportional to the fifth power of impeller radius. In order to compensate the decreased head by the shortened impeller radius, vane angle at impeller outlet should be increased. However, as the vane angle at impeller outlet becomes larger, performance instability occurs at low flow rate regions. In this study, J-Groove is adopted to suppress the performance instability and detailed examination is performed for the influence of the J-Groove on the pump performance. The results show that J-Groove gives good effect on the suppression of performance instability. Moreover, as J-Groove increases pump head considerably, the pump size can be smaller for head requirements.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.9 no.3
• /
• pp.10-17
• /
• 2005

A performance prediction model is developed for partially admitted axial-type turbines. Losses generated within the turbine are classified to the windage loss, expansion loss and mixing loss. The developed loss model is compared with an experimental result. The results predicted with the developed model agree well with the experimental results than those predicted with several other models because this model considers three different kinds of losses. Moreover, this model predicts well the performance even the partial admission is changed. So, this model could be applied to predict the performance of partially admitted axial turbine and it has a high accurate performance.

• Journal of information and communication convergence engineering
• /
• v.13 no.1
• /
• pp.7-14
• /
• 2015

In a multi-hop wireless network, connectivity is determined by the link that is established by the receiving signal strength computed by subtracting the path loss from the transmission power. Two path loss models are commonly used in research, namely two-ray ground and shadow fading, which determine the receiving signal strength and affect the link quality. Link quality is one of the key factors that affect network performance. In general, network performance improves with better link quality in a wireless network. In this study, we measure the network connectivity and performance in a shadow fading path loss model, and our observation shows that both are severely degraded in this path loss model. To improve network performance, we propose power control schemes utilizing link quality to identify the set of nodes required to adjust the transmission power in order to improve the network throughput in both homogeneous and heterogeneous multi-hop wireless networks. Numerical studies to evaluate the proposed schemes are presented and compared.