• Speech Sciences
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• v.11 no.4
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• pp.121-127
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• 2004

This study attempted to provide a spectrum analysis for quantitative evaluation of singing voice quality of singing students rather than the presence or absence of the singer's formant. The regression analysis was used to analyse the relationship between ringing quality, SPR, and SPP of singing voice of college student subjects majoring in music. This study measured singing. power ratio (SPR) in 41 singing students. Digital audio recordings were made in sung vowels for acoustic analyses. Each sample was judged by 1 experienced singing teacher and 4 voice pathologists on one semantic bipolar 7-point scales (ringing-dull). The results showed that the SPR and SPP had significant correlations with ringing quality. The SPR had a significant relationship with ringing quality on singing voice in singing students. The SPR can be an important quantitative measurement for evaluating singing voice quality.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.6
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• pp.78-87
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• 2008

Digital image find own level core media in multimedia as image restoration technology fields, which remove degradation factor for image enhancement, have been growing. Linear space-invariant image restoration algorithm often introduce ringing artifacts near sharp intensity transition areas. This paper presents a new adaptive post-filtering algorithm for reducing ringing artifact. The proposed method extracts an edge map of the image using wavelet transform Based on the edge information, ringing artifacts are detected, and removed by an adaptive bilateral filter. Experimental results show that the proposed algorithm can efficiently remove ringing artifacts with edge preservation.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.39-50
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• 2002

Several pre-processing techniques for earthquake data from earthquake monitoring institutes in Korea including Korea Electric Power Research Institute are thoroughly reviewed. Among these techniques for removing an instrumental response, removing the non-causal ringing distortion by FIR filter, checking calibration status of seismic stations, and minimizing the window effect are introduced and applied to real data. It is also recommended that analysts evaluate S/N ratio in the frequency domain and consider the possibility of using the saturated earthquake data.

• Journal of Korea Multimedia Society
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• v.7 no.10
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• pp.1378-1388
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• 2004

This paper proposes method to improve the image quality degradation that show when reconstructing compressed images at low bit rate by using wavelet transform. The image quality distortion is blocking artifacts and noise in DCT's compression but blocking artifacts of wavelet transform does not appear and ringing artifacts was appeared near the edge. This proposed technique is classified to part which is ringing artifacts of the edge vicinity appears which is not, apply adaptive filter to each region improved image. A edge region which is harsh to the eye is applied by Canny mask and finding strong edge region, search the neighborhood classify the flat region and the texture region, and apply to each region suitable filter, As experiment result, PSNR value of method that is proposed in that low bit rate compression image that ringing artifact appears became low about 0.05db, but 0.023db degree rose strong edge region and nat region's image. Also, showed picture quality improved more than ringing artifacts in nat region when see from subjective viewpoint of human.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05a
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• pp.587-590
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• 2003

본 논문에서는 웨이블릿 변환(wavelet transform)을 이용하여 저 비트율로 압축한 영상을 복원하였을 때 나타나는 화질열화를 개선하는 방법을 제안하였다. 웨이블릿 변환을 이용하여 정지영상을 압축하는 방법에서는 에지부근에 링잉현상(ringing artifacts)이 나타나게 되었다. 이는 강한 에지성분이 있는 곳이므로 캐니 마스크(Canny mask)를 적용하여 강한 에지부근을 찾아낸 후 그 주변을 탐색하여 평탄한 영역(flat region)과 텍스쳐 영역(texture region)을 구분하여 각각에 맞는 필터를 적용하게 된다. 실험결과, 링잉현상이 나타나는 저비트율 압축 영상에서 제안된 방법의 PSNR 값은 0.05db정도 낮아졌지만 인간 시각의 주관적 관점에서 볼 때 평탄한 영역에서의 링잉현상이 보다 개선된 화질을 보였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.587-592
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• 2018

Because the brightness of an AMOLED is determined by the flowing current, each pixel of AMOLED operates via A current driving method. Therefore, it is necessary to supply power to adjust the amount of current according to THE user's requirement for AMOLED driving. In this study, an IP driver block was designed and a simulation was conducted for an AMOLED display, which supplies power as selected by users. The IP driver design focused on regulating the output power due to the OLED characteristics for the diode electric current according to the voltage to be activated by pulse-skipping mode (PSM) under low loads, and 1.5 MHz pulse-width modulation (PWM) for medium/high loads. The IP driver was designed to eliminate the ringing effects appearing from the dis-continue mode (DCM) of the step-up converter. The ringing effects destroy the power switch within the IC, or increase the EMI to the surrounding elements. The IP driver design minimized this through a ringing killer circuit. Mobile applications were considered to enable true shut-down capability by designing the standby current to fall below $1{\mu}A$ to disable it. The driver proposed in this paper can be applied effectively to the same system as the AMOLED display dual power management circuit.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1650-1657
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• 2007

In this paper, we propose an Overlapped Block and an Hanning Window to prevent a Block Discontinuity when we use an algorithm to eliminate ringing artifact which is based on a block structure. The algorithm to eliminate ringing artifact operates with a block structure and 24-RGB data and is based on a modified K-means algorithm. The proposed overlapped block method is piled up one on another per an half of the size of unit-block when an input image is split into several unit-blocks. Therefore, we define a data unit as the unit-block of the block size, $16{\times}16$ pixels. We reconstruct the processed data units into the original form of input image by using an isotropic form of Hanning Window. Finally, in order to evaluate the performance of the abovementioned algorithms, we compare three image, an input image with ringing artifact, an image result obtained by conventional method (non-overlapped), and an image result obtained the proposed method.

• Korea Science and Art Forum
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• v.25
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• pp.379-388
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• 2016

There are some studies to get rid of slice patterns in coronal and sagittal images by FFT(Fast Fourier Transform) and Notch filter. However, the use of a notch filter is the ringing effect according to the rapid frequency change occurs in common. Therefore, this study will be to evaluate the shape and effect of the notch filter. In addition, it is proposed a new notch filter design. Results of the study are as follows. First, Emission-Notch filter was relatively naturally correcting the cutting pattern. Second, Emission-Notch filter to use as Ringing effect is reduced relatively. The next through these findings and further research progress more completely removed the Ringing effect, and expects to reproduce the data close to the actual human body information.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.761-767
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• 2001

In this paper, filtering techniques to reduce the adverse effects of motor leads on high-frequency PWM inverter fed AC motor drives will be examined. The filter was designed to keep the motor terminal from the cable surge impedance to reduce overvoltage reflections, ringing, and the dv/dt, di/dt. Therefore, filtering techniques are investigated to reduce the motor terminal overvoltage, ringing, and EMI noise in inverter fed ac motor drive systems. The output filter is used to limit the rate of the inverter output voltage and reduce EMI(common mode noise) to the motor. The performance of the output filter is evaluated through simulations (PSIM) and experiment on PWM inverter-fed ac motor drive(3phase, 3hp(2.2kw), input voltage 220/380V, induction motor). An experimental PWM drive system reduction of conducted EMI was implemented on an available TMS320C31 microprocessor control board. Finally, experimental results showed that the inverter output filter reduces more CM noise than the LPF(low pass filter) and reduce overvoltage and ringing at the motor terminal.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.14-20
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• 2012

This paper presents a design and topology selection of bi-direcional buck converter based on PV PCS for managing the electric power. Futhermore, Current Ringing on DCM bi-directional buck converter for soft switching is analyzed in detail. PSIM Simulation and Experiments at the various operating points show the propriety of this paper. Building on the result of simulation and experiment, a comparative analysis is performed with the approximate estimate. By use of a study, the selecion of switch and diode which improve efficiency of the overall system is appiled to DCM bi-directional buck converter based on PV PCS.