• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.645-648
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• 2001

본 논문에서는 H.26L 동영상 압축 표준화 방식에서 블록화 및 링 현상을 동시에 제거하는 계산량이 감소된 일차원 loop filter를 제안한다. 새로운 일차원 정규화 완화 함수가 정의되고 두 개의 인접 방향에서 완화의 정도를 조절하는 정규화 매개변수는 부호화와 복호화 부에서 이용 가능한 코드화 블록 패턴과 양자화 스텝크기로 정의된다. 그러므로, 정규화 매개변수를 정의하고 압축된 동영상으로부터 복원된 영상을 얻기 위한 기타 정보는 필요하지 않다. 실험결과로부터 제안된 알고리즘의 성능은 확인할 수 있었다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.109-112
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• 2000

An algorithm for the reduction of blocking artifacts is pro-posed. Instead of filtering the pixels by a digital filter, the proposed algorithm considers the compressed image as continuous-time ,signal and replaces it by a pre-designed lowpass filter outputs. The algorithm shows better performance than the conventional methods in low activity region, and comparable or a little worse objective performance in high activity region. Hence, by applying the proposed algorithm to the low activity region and the conventional ones to the high activity region, the objective and subjective performances are improved in most cases.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.315-318
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• 2013

A novel foveation filter method is proposed in DCT domain. For countering the blocking and ringing artifacts, we devise the tools measuring the signal gradient, the block signal variations in the DCT domain. Each measurement is properly applied to each enhancement region and smoothing region. The proposed method optimally adapts the enhancement factors to the characteristics of the underlying signals and so maximizes the enhancement performances with significantly suppressing the artifacts. The subjective and objective evaluations verify that the proposed method sustains producing the improved video qualities for various sequences without tuning any parameters to individual sequences.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06a
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• pp.242-243
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• 2010

Reducing compression artifacts such as ringing and blocking is one of important issues to improve a visual quality of a JPEG compressed image. In this paper, we propose a new post processing technique based on bilateral filtering (BF), which is one of the techniques that are used to reduce compression artifacts. An important issue with the application of the BF is the selection of the filter parameters, which affects the result significantly. In this work, we suggest a new method to select the filter parameter automatically. In addition to artifact reduction using the BF, a contrast enhancement is performed to overcome the contrast loss problem due to compression. The experimental result shows that the proposed approach can alleviate the artifacts efficiently.

• Radiation Oncology Journal
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• v.6 no.1
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• pp.109-116
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• 1988

The Alcyon Co-60 gamma rays was studied for electron contamination. The surface dose, attributable almost entirely to contamination electrons, has a linear dependence on field width for square fields and an inverse square dependence on distance from the bottom of the fixed head assembly Build-up and surface dose measurements were taken with and without an acrylic blocking tray in place. Further measurements were made with a copper filter designed to reduce secondary electrons emitted by photon interactions with the acrylic tray. The results are discussed in relation to skin sparing effect for radiation therapy Patients. And to achieve the maximum skin sparing effect, the selection of the optimum SSD and TSD is needed.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.224-228
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• 2003

In this paper, for phase lock loop(PLL) synthesizer, we introduce a novel but simple and low cost frequency modulation(FM) circuit of a flat peak frequency deviation for modulation signal from high to very low frequency penetrating into the loop-bandwidth of PLL. The FM circuit was basically designed to compensate an amount of feedback of the loop filter in PLL. The circuit also includes the capability of the adjustment of peak frequency deviation and blocking the interference with the loop filter. The designed circuit was successfully implemented and showed the flat frequency deviation as expected in the design.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.255-259
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• 2003

The noise canceling on gray image morphing with median filter is presented. The processing is that interpolate the image with B-spline, specify the distinctive points, cancel the noise by median filtering and perform the morphing. The experiment results denoise the blocking degradation as 20%, correct and present a soft morphing image processing.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.598-602
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• 2002

This paper presents the 3-phase hybrid series active power filter with dynamic voltage restorer(DVR) which serve as an energy buffer and current harmonics blocking resistor connected to sensitive loads, such as, to compensate voltage dips and current harmonics in power distribution system. The DVR is to inject a dynamically controlled voltage generated by a forced commutated converter in series to the bus voltage by means of a booster transformer. The momentary amplitudes of the three injected phase voltages are controlled such as to eliminate any detrimental effects of a bus fault to the load voltage. The proposed system is able to simultaneously compensate current harmonics, voltage fluctuating and voltage unbalance in power distribution systems. The reference phase angle detected by synchronized with the positive sequence component of the unbalanced source by using symmetrical component transformation. The effectiveness of proposed system is verified by the computer simulation.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.3
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• pp.137-143
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• 2014

Demand Controller is a load control device that monitor the current power consumption and calculate the forecast power to not exceed the power set by consumer. Accurate demand forecasting is important because of controlling the load use the way that sound a warning and then blocking the load when if forecasted demand exceed the power set by consumer. When if consumer with fluctuating power consumption use the existing forecasting method, management of demand control has the disadvantage of not stable. In this paper, load forecasting of the unit of seconds using the Exponential Smoothing Methods, ARIMA model, Kalman Filter is proposed. Also simulation of load forecasting of the unit of the seconds methods and existing forecasting methods is performed and analyzed the accuracy. As a result of simulation, the accuracy of load forecasting methods in seconds is higher.

• Journal of the Korean Society of Radiology
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• v.8 no.6
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• pp.301-307
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• 2014

In this study, an image acquired by the DSA(Digital Subtraction Angiography) system that is configured to configure the algorithm for high pass filtering algorithm experiments to improve the quality of angiography methods proposed. high pass filter is a high-frequency components pass through the filter, blocking low-frequency components. Part of the boundary line and contour of the organ corresponds to the high-frequency component is a high-frequency component of a medical image. Therefore, the high pass filter is also used for detection of the boundary line, but is also used for the high frequency enhancement. It was able to be analyzed by the proposed algorithm, to improve the quality of the angiography. Found out that the expression of the target site stand out clearly. The quality of the DSA system proposed in the wrong diagnosis software can be used to reduce, it is possible to develop and will further improve the accuracy of the treatment.