• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.997-1002
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• 2003

Roller-compacted concrete(RCC) dam is a new type that combines advantages of earthfill dam and concrete dam in construction, This method save cost due to their rapid method of construction. RCC is, used in RCC dams, no-slump concrete so it is different that measure method of consistency and mixture properties compare with conventional mass concrete, There are existing two major design method, which one used in USA the other used in Japan. The results obtained in this study would be useful in establishing mixture proportions for dam concrete for RCC dams by apply method of compound their merit.

• Journal of Computing Science and Engineering
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• v.10 no.2
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• pp.68-73
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• 2016

An efficient texture compression method is proposed based on a block matching process between the current block and the previously encoded blocks. Texture mapping is widely used to improve the quality of rendering results in real-time applications. For fast texture mapping, it is important to find an optimal trade-off between compression efficiency and computational complexity. Low-complexity methods (e.g., ETC1 and DXT1) have often been adopted in real-time rendering applications because conventional compression methods (e.g., JPEG) achieve a high compression ratio at the cost of high complexity. We propose a block matching-based compression method that can achieve a higher compression ratio than ETC1 and DXT1 while maintaining computational complexity lower than that of JPEG. Through a comparison between the proposed method and existing compression methods, we confirm our expectations on the performance of the proposed method.

• International Journal of Contents
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• v.15 no.4
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• pp.27-35
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• 2019

In this paper, we propose an advanced Minimum Mean Square Error (MMSE) channel estimation method for IEEE 802.11p/Wireless Access in Vehicular Environments (WAVE) systems. To improve the performance of MMSE method, we apply the Weighted Sum using Update Matrix (WSUM) scheme to the step of calculating the instantaneously estimated channel and then, a time domain selectively averaging method is applied after the WSUM scheme. Based on that, the accuracy of instantaneously estimated channel increases and then, the accuracy of auto covariance matrix also increases. Consequently, we can achieve the performance gain over the conventional MMSE method. Through simulations based on the IEEE 802.11p standard, it is confirmed that the proposed scheme can outperform the existing channel estimation schemes.

• ETRI Journal
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• v.42 no.6
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• pp.815-826
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• 2020

We propose a two-dimensional (2D) scattering-center-extraction (SCE) method using sparse recovery based on the compressive-sensing theory, even with data missing from the received radar cross-section (RCS) dataset. First, using the proposed method, we generate a 2D grid via adaptive discretization that has a considerably smaller size than a fully sampled fine grid. Subsequently, the coarse estimation of 2D scattering centers is performed using both the method of iteratively reweighted least square and a general peak-finding algorithm. Finally, the fine estimation of 2D scattering centers is performed using the orthogonal matching pursuit (OMP) procedure from an adaptively sampled Fourier dictionary. The measured RCS data, as well as simulation data using the point-scatterer model, are used to evaluate the 2D SCE accuracy of the proposed method. The results indicate that the proposed method can achieve higher SCE accuracy for an incomplete RCS dataset with missing data than that achieved by the conventional OMP, basis pursuit, smoothed L0, and existing discrete spectral estimation techniques.

• Journal of Korea Multimedia Society
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• v.7 no.12
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• pp.1671-1679
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• 2004

This study has proposed visual-feature extraction methods for each band in wavelet domain with both spatial frequency features and multi resolution features. In addition, it has brought forward similarity measurement method using fuzzy theory and new color feature expression method taking advantage of the frequency of the same color after color quantization for reducing quantization error, a disadvantage of the existing color histogram intersection method. Experiments are performed on a database containing 1,000 color images. The proposed method gives better performance than the conventional method in both objective and subjective performance evaluation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.107-112
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• 2017

The purpose of this study was to develop an extractor to improve the effective ingredient of propolis. In order to improve the performance of conventional alcohol extraction at room temperature, a striking-type extractor used with a sprayed mist (alcohols, 95% alcohol) was developed for use at $40^{\circ}C$. Extraction of the effective ingredient of propolis was tested, and the resulting material was analyzed using a device. The extraction test of the mist spraying method indicated that the level of flavonoid was 1.56%, which is 1.5 times the 1.04% shown in existing data from a conventional stirred extractor. In addition, the extraction time can be reduced by half and the cost reduced by about 12.7% per year. It is confirmed that the extractor developed with a sprayed mist (alcohols, 95% alcohol) appears effective at the low temperature.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.3
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• pp.66-74
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• 2004

In this paper the authors presents a new method, named FR-SERVQUAL, of evaluating perceived service quality in Public Sectors, using triangle fuzzy numbers and semantic differential scale. By conventional quantification methods, it is not easy to express the notion of a linguistic variables and customers' subjective judgements. In contrast to the conventional PZB methods which express the customers' perception of quality as a function of gap between the expected and perceived service, this paper suggests to use the ratio of the two. Through an application example, this paper shows that the current FR-SERVQUAL approach provides a more realistic way of measuring service quality compared to existing methods.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.1
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• pp.29-37
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• 2012

A simple and effective dead time compensation scheme for a PWM inverter-fed permanent magnet synchronous motor (PMSM) drive using the model reference adaptive control (MRAC) and coordinate transformation is presented. The basic concept is to first transform a time-varying disturbance caused by the dead time and inverter nonlinearity into unknown constant or slowly-varying one by the coordinate transformation, and then use the MRAC design technique to estimate this parameter in the stationary reference frame. Since the MRAC scheme is a suitable way of estimating such a parameter, the control performance can be significantly improved as compared with the conventional observer-based method tracking time-varying parameters. In the proposed scheme, the disturbance voltage caused by the dead time is effectively estimated and compensated by on-line basis without any additional circuits nor existing disadvantages as in the conventional methods. The asymptotic stability is proved and the effectiveness of the proposed scheme is verified.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.404-406
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• 2013

An image edge has been utilized as preprocessing procedure in various field such as object detection, object recognition. there are Sobel, Prewitt, Roberts, Laplacian as conventional edge detection methods. existing methods are implement is simple, but edge detection characteristics is insufficient in impulse noise area. Therefore, to compensate the defect of conventional methods, in this paper, an edge detection algorithm using modified mask is proposed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.271-276
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• 2014

LED lighting has received worldwide attention as advantages, such as environment-friendly than the conventional light, the excellent energy efficiency, and a semi-permanent lifetime. The use of the SMPS increased with the rapid growth in the LED industry. Increased use of SMPS means an increase in the harmonic generation load. Therefore, LED lighting compared with conventional fluorescent lamps were tested in this paper for characterized by a light source, electrical and harmonic characteristics. Experiments results for LED lighting showed different characteristics from the existing fluorescent lamp. Especially harmonic characteristic results showed different characteristics in accordance with the power device manufacturing method for LED lighting.