• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.10
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• pp.821-826
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• 2012

Two-dimensional magnetic recording (TDMR) is treated as the next generation magnetic recording method, but because of its high channel bit error rate, it is difficult to use in practices. In this paper, we introduce a new writing method that can decrease the nonlinear media error effectively, and it can also achieve 10 Tb/$in^2$ of user bit density on a magnetic recording medium with 20 Teragrains/$in^2$.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.54-55
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• 2015

In this paper, we propose a method pursuing robustness in ad hoc network system when the CSI of interferers is unavailable. The non-parametric linear minimum mean square error filter is exploited to achieve large fraction of the MMSE filter transmission capacity employing the perfect covariance matrix information. From the numerical results, we show that the proposed scheme brings substantial transmission capacity gain over conventional MMSE filter using sample covariance matrix.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.302-315
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• 2018

Highly non-linear electro-optical transfer function of the Perceptual Quantizer was approximated by a truncated Taylor series, resulting in a closed form solution for luma adjustment. This previous solution is fast and quite suitable for the hardware implementation of luma adjustment, but the approximation error becomes relatively large in the range of 600~3,900 cd/m2 linear light. In order to reduce such approximation error, we propose a new linear model, for which a correction is performed on the position and the slope of line based on the scope of approximation. In order to verify the approximation capability of the proposed linear model, a comparative study on the luma adjustment schemes was conducted using various high dynamic range test video sequences. Via the comparative study, we identified a significant performance enhancement over the previous fast luma adjustment scheme, where a 4.65dB of adjusted luma t-PSNR gain was obtained for a test sequence having a large portion of saturated color pixels.

• 전자공학회논문지 IE
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• v.44 no.1
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• pp.15-19
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• 2007

A study to have read does an improvement of an error restoration technology based on the edge direction interpolation that a stop image cared for inside frame correction more than with an image restoration way of a transfer error or with an aim. A way proposed to is based on edge direction detection method of a block utilizing the edge direction which will adjust a part damaged a sweater to a remaining part here. The rest of error pixel used non linear Midian filter for process later data information by the final stage and did interpolation. The examination result shows a good recuperation tendency and low accounts time of a way proposed to realization possibility of a real time image processing.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.1
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• pp.1-14
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• 2023

Underwater images carry information that is useful in the fields of aquaculture, underwater military security, navigation, transportation, and so on. In this research, we transmitted an underwater image through various underwater mediums in the presence of underwater turbulence and beam attenuation effects using a high-speed visible optical carrier signal. The optical beam undergoes scintillation because of the turbulence and attenuation effects; therefore, distorted images were observed at the receiver end. To understand the behavior of the communication media, we obtained the bit error rate (BER) performance of the system with respect to the average signal-to-noise ratio (SNR). Also, the structural similarity index (SSI) and peak SNR (PSNR) metrics of the received image were evaluated. Based on the received images, we employed suitable nonlinear filters to recover the distorted images and enhance them further. The BER, SSI, and PSNR metrics of the specific nonlinear filters were also evaluated and compared with the unfiltered metrics. These metrics were evaluated using the on-off keying and binary phase-shift keying modulation techniques for the 50-m and 100-m links for beam attenuation resulting from pure seawater, clear ocean water, and coastal ocean water mediums.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.977-985
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• 2011

Recent works on multiuser transmission techniques have shown that the linear growth of capacity in single user MIMO system can be translated to the multiuser MIMO scenario as well. In this paper, we propose a method pursuing performance gain of vector perturbation in multiuser downlink systems. Instead of employing maximum number of mobile users for communication, we use small part of them as virtual users for improving reliability of users participating communication. By controlling parameters of virtual users including information and perturbation vector, we obtain considerable improvement in the effective SNR, resulting in large gain in bit error rate performance. Simulation results on the realistic multiuser downlink systems show that the proposed method brings substantial performance gain over the standard vector perturbation with marginal overhead in computations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1853-1858
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• 2021

O-rings fill the gaps between mechanical parts. Until now, the sorting of defective products has been performed visually and manually, so classification errors often occur. Therefore, a camera-based defect classification system without human intervention is required. However, a binarization process is required to separate the required region from the background in the camera input image. In this paper, an adaptive binarization technique that considers the surrounding pixel values is applied to solve the problem that single-threshold binarization is difficult to apply due to factors such as changes in ambient lighting or reflections. In addition, the convex hull technique is also applied to compensate for the missing pixel part. And the learning model to be applied to the separated region applies the residual error-based deep learning neural network model, which is advantageous when the defective characteristic is non-linear. It is suggested that the proposed system through experiments can be applied to the automation of O-ring defect detection.

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1221-1234
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• 2013

The purpose of this study is to suggest the methodology for the computation of uplift pressure and discharge of the seepage flow under gravity dam. A 3-dimensional FDM model is developed for this purpose and this model can simulate the saturated Darcian flow in heterogeneous media. For the verification of the numeric model, test simulation has been executed and the mass balance has been checked. The error does not exceed 3%. Using the developed model, The uplift pressure and seepage flow discharge under gravity dam has been calculated. The uplift pressure shows the similar pattern, comparing with the result of flow-net method. As the length of grout curtain increases, the uplift pressure decreases linearly, but the seepage flow discharge shows the non-linear decreasing pattern. The coefficients of the formulas in the dam-design criteria have been analysed, and ${\alpha}=1/3$ corresponds to the value when the length of curtain grout is 70% of the aquifer height. The uplift pressure near the pressure relief drain has the big curvature vertically and horizontally. The developed model in this study can be used for the evaluation of the effects of seepage flow under gravity dam.