• 대한전자공학회논문지
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• 제25권6호
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• pp.694-699
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• 1988

Optical phase conjugate mechanism and edge enhancement by degenerate four wave mixing (DFWM) in photorefractive material are described, and image reconstruction is perfromed sucessfully in BaTiO3 single crystal. Also, the edge enhancement is carried out in the crystal by the same DFWM geometry. But the intensities of three incident beams are inverted. Good quality of edge enhancement is observed in real-time (processing time 10 sec) with low incident light intensity (5.38mW/cm\ulcorner.

• IEIE Transactions on Smart Processing and Computing
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• 제3권2호
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• pp.52-58
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• 2014

Exact histogram specification (EHS) transforms the histogram of an input image into the specified histogram. In the conventional EHS techniques, the pixels are first sorted according to their graylevels, and the pixels that have the same graylevel are further differentiated according to the local average of the pixel values and the edge strength. The strictly ordered pixels are then mapped to the desired histogram. However, since the conventional sorting method is inherently dependent on the initial graylevel-based sorting, the contrast enhancement capability of the conventional EHS algorithms is restricted. We propose a modified EHS algorithm considering the just noticeable difference. In the proposed algorithm, the edge pixels are pre-processed such that the output edge pixels obtained by the modified EHS can result in the local contrast enhancement. Moreover, we introduce a new sorting method for the pixels that have the same graylevel. Experimental results show that the proposed algorithm provides better image enhancement performance compared to the conventional EHS algorithms.

• 대한가정학회지
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• 제35권3호
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• pp.1-13
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• 1997

Recently, much of attention has been given to the role of values in pro-environmental behaviors. The reasons are that most of environmental pollution comes from the home-living and polluting behavior is motivated by the undesirable value pursuing self-interests. This study is designed to investigate the effect of values on environmental behaviors. The results of this study are as following: Homemakers' value structure had 'self-transcendence·conservation' value, 'self-enhancement·conservation' value and 'openness-to-change' value as value factors. And the homemakers thought of self-transcendence·conservation value as "most important" and self-enhancement·conservation value as "not important". Consequently, homemakers had a tendency to do more pro-environmental behaviors when they perceived self-transcendence·conservation value as "more important value", while they did less when they regarded self-enhancement·conservation value as "more important". Therefor self-transcendence·whereas self-enhancement·conservation value is a negative predictor. Especially, self-transcendence·conservation value had more influence on pro-environmental behaviors than self-enhancement·conservation value.

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.681-691
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• 2006

Nucleate boiling heat transfer for refrigerants, R113, and R113+wt4% ethanol mixture, an azeotropic mixture under electric field was investigated experimentally in a single-tube shell/ tube heat exchanger. A special electrode configuration which provides a more uniform electric field that produces more higher voltage limit against the dielectric breakdown was used in this study. Experimental study has revealed that the electrical charge relaxation time is an important parameter for the boiling heat transfer enhancement under electric field. Up to 1210% enhancement of boiling heat transfer was obtained for R113+wt4% ethanol mixture which has the electrical charge relaxation time of 0.0053 sec whereas only 280% enhancement obtained for R113 which has relaxation time of 0.97 sec. With artificially machined boiling surface, more enhancement in the heat transfer coefficient in the azeotropic mixture was obtained.

• 한국멀티미디어학회논문지
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• 제20권9호
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• pp.1481-1490
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• 2017

This paper presents an image quality enhancement algorithm for dark image acquired under poor lighting condition. Various retinex algorithms which are human perception-based image processing methods were proposed to solve this problem. Although MSR(Multi-Scale Retinex) among these algorithm works well under most lighting condition, it shows color degradation because their separate nonlinear processing of RGB color channels. To compensate for the loss of the color, MSRCR(Multi-Scale Retinex with Color Restoration) was proposed. However, it requires high computational load and has additional parameters that need to be adjusted according to input image. In order to overcome this problem, a new retinex algorithm based on MSR is proposed in this paper. The proposed method consists of V channel MSR, saturation correction, and separate contrast enhancement process. Experimental results show that the subjective and objective image quality of the proposed method better than those of the conventional methods.

• 말소리와 음성과학
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• 제4권4호
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• pp.87-92
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• 2012

Speech enhancement aims to improve speech quality by removing background noise from noisy speech. Independent vector analysis is a type of frequency-domain independent component analysis method that is known to be free from the frequency bin permutation problem in the process of blind source separation from multi-channel inputs. This paper proposed a new method of microphone array based speech enhancement that combines independent vector analysis and beamforming techniques. Independent vector analysis is used to separate speech and noise components from multi-channel noisy speech, and delay-sum beamforming is used to determine the enhanced speech among the separated signals. To verify the effectiveness of the proposed method, experiments for computer simulated multi-channel noisy speech with various signal-to-noise ratios were carried out, and both PESQ and output signal-to-noise ratio were obtained as objective speech quality measures. Experimental results have shown that the proposed method is superior to the conventional microphone array based noise removal approach like GSC beamforming in the speech enhancement.

• Biomolecules & Therapeutics
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• 제19권1호
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• pp.109-117
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• 2011

In this work, we have investigated the effect of polyoxyethylene alkyl ester nonionic surfactants on percutaneous permeation enhancement of a model drug, ketoprofen. We also investigated the mechanism involved in the enhancement using impedance and solubility measurement. Three groups of nonionic surfactants with different ethylene oxide content were studied. The permeation results showed that all surfactants enhanced the percutaneous absorption, irrespective of the molecular weight. The permeation results from PEG-45 monostearate (PEGMS45) were rather unexpected. Impedance and solubility results indicate that the mechanism involved in the enhancement of permeation by PEG-10 monooleate (PEGMO10) and PEGMS45 is rather different. The results from PEGMS45 suggest that it could be a potential candidate as a skin penetration enhancer with high molecular weight, which may poses less skin irritation and systemic side effect than the smaller surfactant molecules. Overall, this work provided some useful information on percutaneous transport enhancement and the mechanistic insights involved in skin permeation for these nonionic surfactants.

• 방송공학회논문지
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• 제8권1호
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• pp.11-18
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• 2003

본 논문에서는 잡음 에너지에 의한 지각적 간섭현상 해석을 통한 지각적 컨벌루션 잡음 제어에 의한 음질 개선 방법을 연구하였다. 지각적 컨벌루션 잡음은 잡음에 의한 신호의 지각적인 특성 변화 및 잡음 추정오차에 의한 잔여 잡음의 영향을 반영하는 것이다. 실험 결과 임계대역 여기 에너지를 통한 지각적 부가 잡음 제어 필터와 순음도 변화도를 통한 지각적 컨벌루션 잡음 제어 필터가 대등한 음질 개선 성능을 나타내었으며, 다양한 잡음 환경에서도 우수한 음질 개선을 나타냄을 확인 할 수 있었다.

• The Journal of the Acoustical Society of Korea
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• 제22권4E호
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• pp.161-166
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• 2003

We present an adaptive wavelet packet based speech enhancement method with robust voice activity detection (VAD) in non-stationary noise environment. The proposed method can be divided into two main procedures. The first procedure is a VAD with adaptive wavelet packet transform. And the other is a speech enhancement procedure based on the proposed VAD method. The proposed VAD method shows remarkable performance even in low SNRs and non-stationary noise environment. And subjective evaluation shows that the performance of the proposed speech enhancement method with wavelet bases is better than that with Fourier basis.

• KIEE International Transactions on Power Engineering
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• 제5A권2호
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• pp.152-158
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• 2005

This paper describes a reactive optimal power flow incorporating margin enhancement constraints. Margin sensitivity at a steady-state voltage instability point is calculated using invariant space parametric sensitivity, and it can provide valuable information for selection of effective control parameters. However, the weakest buses in neighboring regions have high margin sensitivities within a certain range. Hence, the control determination using only the sensitivity information might cause violation of operational limits of the base operating point, at which the control is applied to enhance voltage stability margin in the direction of parameter increase. This paper applies an interior point method (IPM) to solve the optimal power flow formulation with the margin enhancement constraints, and shunt capacitances are mainly considered as control variables. In addition, nonlinearity of margin enhancement with respect to control of shunt capacitance is considered for speed-up control determination in the numerical example using the IEEE 118-bus test system.