• 해양환경안전학회지
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• 제6권1호
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• pp.47-55
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• 2000

A three-dimensional digital image processing technique is proposed to quantitatively predict the dispersion phenomena of oil droplet onto the surface of the water. This technique is able to get the dispersion rate of an oil droplet three-dimensionally just below the surface of the water over time. The obtained dispersion rate obtained through this technique is informative to the investigation into the relationship among the gravity, surface tensions between oil, water, and air. This technique is based upon the three-dimensional PIV(Particle Imaging Velocimetry) technique and its system mainly consists of a three CCD(Charge Coupled Device) cameras, an image grabber, and a host computer in which an image processing algorithm is adopted for the acquisition of dispersion rate oil an oil droplet.

• Journal of information and communication convergence engineering
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• 제9권5호
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• pp.591-596
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• 2011

Image denoising is a key issue in all image processing researches. Generally, the quality of an image could be corrupted by a lot of noise due to the undesired conditions of image acquisition phase or during the transmission. Many approaches to image restoration are aimed at removing either Gaussian or impulse noise. Nevertheless, it is possible to find them operating on the same image, which is called mixed noise and it produces a hard damage. In this paper, we proposed noise type classification method and a mixed nonlinear filter for mixed noise suppression. The proposed filtering scheme applies a modified adaptive switching median filter to impulse noise suppression and an efficient nonlinear filer was carried out to remove Gaussian noise. The simulation results based on Matlab show that the proposed method can remove mixed Gaussian and impulse noise efficiently and it can preserve the integrity of edge and keep the detailed information.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1389-1399
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• 2013

A discrete controller is designed for low power dc-dc switched mode power supplies. The approach is based on time domain and the control loop continuously and concurrently tunes the compensator parameters to meet the converter specifications. A digital state feedback control combined with the load estimator provides a complete compensation, which further improves the dynamic performance of the closed loop system. Simulation of digitally controlled Buck converter is performed with MATLAB/Simulink. Experimental results are given to demonstrate the effectiveness of the controller using LabVIEW with a data acquisition card (model DAQ Pad - 6009).

• Journal of information and communication convergence engineering
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• 제6권1호
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• pp.80-85
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• 2008

Images are often corrupted by noises during signal acquisition and transmission. Among those noises, additive white Gaussian noise (AWGN) and impulse noise are most representative. For different types of noise have different characters, how to remove them separately from degraded image is one of the most fundamental problems. Thus, a modified image restoration algorithm is proposed in this paper, which can not only remove impulse noise of random values, but also remove the AWGN selectively. The noise detection step is by calculating the intensity difference and the spatial distance between pixels in a mask. To divide two different noises, the method is based on three weighted parameters. And the weighted parameters in the filtering mask depend on spatial distances, positions of impulse noise and standard deviation of AWGN. We also use the peak signal-to-noise ratio (PSNR) to evaluate restoration performance, and simulation results demonstrate that the proposed method performs better than conventional median-type filters, in preserving edge details.

• Journal of electromagnetic engineering and science
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• 제9권4호
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• pp.182-187
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• 2009

When we assign frequency resources to a new radio service, the existing services need not to be interfered with by the new service. Therefore, when we make a frequency assignment, a guard band is necessary to separate adjacent frequency bands so that both can transmit simultaneously without interfering with each other. In this paper, we propose an efficient frequency guard band decision rule for avoiding interference between radio services. The guard band is established based on the probability of interference in the previously arranged scenario. The interference probability is calculated using the spectrum engineering advanced Monte Carlo(MC) analysis tool(SEAMCAT). After applying the proposed algorithm to set up the frequency guard band, we can decide on the guard band appropriately because the result satisfies the predefined criterion.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.340-343
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• 2003

This study presents a practical procedure for the Bayesian inversion of geophysical data by Markov chain Monte Carlo (MCMC) sampling and geostatistics. We have applied geostatistical techniques for the acquisition of prior model information, and then the MCMC method was adopted to infer the characteristics of the marginal distributions of model parameters. For the Bayesian inversion of dipole-dipole array resistivity data, we have used the indicator kriging and simulation techniques to generate cumulative density functions from Schlumberger array resistivity data and well logging data, and obtained prior information by cokriging and simulations from covariogram models. The indicator approach makes it possible to incorporate non-parametric information into the probabilistic density function. We have also adopted the MCMC approach, based on Gibbs sampling, to examine the characteristics of a posteriori probability density function and the marginal distribution of each parameter. This approach provides an effective way to treat Bayesian inversion of geophysical data and reduce the non-uniqueness by incorporating various prior information.

• 한국멀티미디어학회논문지
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• 제6권5호
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• pp.921-927
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• 2003

자연생태환경에서의 하천변화에 대한 연구는 관찰자가 상주해야하는 문제점과 사람의 주관적인 분석으로 인해 부정확한 결과물을 초래한다. 본 논문은 자연하천생태의 현장조사를 통한 자료획득과 동수역학 모형의 모의를 바탕으로 정확한 분석을 통한 자원관리 및 평가를 할 수 있는 모델을 제안한다. 하천의 생태에서의 유체의 변화는 신경회로망을 이용하여 충돌을 감지하였다. 실험결과, 충돌감지에 따르는 시간비용을 줄였으며, 그 정확도 또한 우수하였다.

• 제어로봇시스템학회논문지
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• 제12권10호
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• pp.1050-1055
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• 2006

Since the muiltipath signal arrives at the GPS receiver later than the line-of-sight signal, the multipath signal makes the shape of the correlation function asymmetric. This paper proposes a multipath mitigation method through asymmetry estimation of the correlation function, in which multiple correlators are utilized. The asymmetry is estimated from correlation values of correlators which have different chip spacings. Based on the estimated asymmetry, the correlation function is modified in order to get a better code tracking performance. Even through the proposed method uses multiple correlators including the narrow correlator, the acquisition performance is not degraded since the number of search cell of the narrow correlator part can be reduced in the algorithm of the proposed method. The simulation results show that the proposed method gives better performance than the generic correlator in multipath environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2082-2085
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• 2002

This paper describes the development of a gas turbine engine simulator in detail. The simulator presented in this paper has a mathematical engine model based on a target gas turbine engine performance data and is developed for generating a gas turbine engine sensor signals between the hardwares and softwares of a gas turbine engine control system using Data Acquisition systems(DAS) and 1553B communication, a aeronautic standard communication specification. In addition, this paper proves the excellent performance of this simulator by showing the results of a gas turbine engine field test and simulation.

• 전자공학회논문지B
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• 제28B권11호
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• pp.925-933
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• 1991

Conventional stereo matching techniques are based on the assumption that the features representing an object in left and right images have fixed attribute values. But, in fact, such features may take different values due to the practical stereo image formation and the image acquisition error, and thus the conventional techniques tend to result in the in the incorrect matching of features. In this paper, we propose a stereo matching mathod with a possibilistic view which copes with the possible variability of feature values. As a result, this method decreases the number of incorrect matching features when the values of corresponding features are somewhat large. The effectiveness of the proposed method is shown via computer simulation.