• Journal of Astronomy and Space Sciences
• /
• v.24 no.4
• /
• pp.261-268
• /
• 2007

We have studied the temporal variation in the North-South asymmetry of the sunspot area during the period from 1874 to 2007. Though the 9-year periodicity is commonly reported, shorter periodicities is still under study. We employ the cepstrum analysis method to analyze the noisy power spectrum of the North-South asymmetry. We demonstrate that the cleaned power spectrum shows reduction of the spurious back-ground noise level. Some of short period peaks in the power spectrum disappear after deconvolution. It should be, however, pointed out that power spectrum might look less noisy because of a filtering process during deconvolution. We conclude by pointing out that a more sophisticate filtering algorithm is required to produce a precise and reliable periodicity estimate.

• Journal of Korea Multimedia Society
• /
• v.20 no.6
• /
• pp.865-872
• /
• 2017

Recent advance in electronics and scintillators makes it possible to utilize the time-of-flight (TOF) information in improving image reconstruction of positron emission tomography(PET). In this paper, we propose a TOF-based fast image reconstruction method for PET. The proposed method uses the deconvolution of TOF data for each angle view and the rotational averaging of deconvolved images. Simulation results show an improved performance of the proposed method, as compared with filtered backprojection (FBP) method, TOF-FBP, and TOF version of expectation-maximization(EM) methods. Simulation results also show a great potentiality of the proposed method in limited angle tomography applications.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2000.11a
• /
• pp.29-33
• /
• 2000

The classical image reconstruction for stripmap SAR is based on the Fresnel approximation which utilizes deramping or chirp deconvolution in the synthetic aperture(slow-time) domain. Another approach in formulating stripmap SAR processing and imaging is based on the SAR wavefront reconsturction theory, and analysis of the SAR signal in the slow-time via the spherical wave Fourier decomposition of the radar radiation pattern. In this paper, we compare the Fresnel approximation and the wavefrong reconstruction methods using simulated stripmap SAR dada.

• Journal of the Korean Wood Science and Technology
• /
• v.26 no.2
• /
• pp.51-58
• /
• 1998

Structural changes of cellulosic fibres during the papermaking process were studied by analysis of FTIR spectra collected by the transmission method. The spectra were obtained from a carefully prepared handsheet, using a special infra-red (IR) cell suitable for evacuating the sample. The deconvolution technique was also applied for sharpening the FTIR spectra in the frequency range of the OH and CH stretching bands, which gave detailed information on the structural changes of cellulose. The intensity of some bands was decreased by predrying the sample as a result of the removal of adsorbed moisture. An increase in intensity of some bands in the frequency range of 3700 to $3200cm^{-1}$ was shown at a higher beating level. This increase in intensity was caused by changes in the crystal domain of cellulose resulting from the exposure of the crystalline area on the fibre surface.

• IEIE Transactions on Smart Processing and Computing
• /
• v.5 no.5
• /
• pp.319-322
• /
• 2016

We propose a parametric blind deconvolution method for bi-level images with unknown intensity levels that estimates unknown parameters for point spread functions and images by minimizing a penalized nonlinear least squares objective function based on normalized correlation coefficients and two regularization functions. Unlike conventional methods, the proposed method does not require knowledge about true intensity values. Moreover, the objective function of the proposed method can be effectively minimized, since it has the special structure of nonlinear least squares. We demonstrate the effectiveness of the proposed method through simulations and experiments.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2005.04a
• /
• pp.139-142
• /
• 2005

Kim and Lee(2005) suggested Minimum Entropy Deconvolution(MED) to estimate the temporal sequence of the relative recharge. However this study by Kim and Lee(2005) was just related to the verification of the conceptual approach with MED. In this study, we try to characterize the applicability of MED in the case of spatially heterogeneous recharge (distance from recharge area). Simulated results were recorded with some specific sampling points. Estimated results from this study show higher than 0.8 in cross-correlation with the original recharge sequence.

• Proceedings of the KOSOMBE Conference
• /
• v.1997 no.05
• /
• pp.366-369
• /
• 1997

In this study, we measured upper right, lower right, upper left region to find the optimal region which represent liver function. We found that the upper right region is optimal because of high accuracy and low standard deviation. For normal subjects all the calculated HEFs were greater than 100% and all those of abnormal ones were less than 80%. Thus HEF can be assumed to discriminate abnormal livers from normal ones. It was found that the patients with surgical operation would survive if both the pre-and the post-operative HEFs are greater than 50%. Therefore HEF method can be a good estimator for surgeon to determine the surgical operation and to evaluate remaining hepatic function after surgery as well as it is reliable and simple.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.6
• /
• pp.19-27
• /
• 1985

In most engineering problems the output of linear system could be expressed by a con-volution of finite input and impulse response. In this paper, the deconvolution algorithm based on the reconstruction of residue polynomials to get a convolution factor, impvlse response or system input, were considered. Two techniques, using a matrix and Euclid's algorithm were discussed. In the illustrated examples, the result showed high accuracy about 10-10 RMS error.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.277-280
• /
• 2000

수중환경에서 표적의 탐지 성능을 향상시키기 위하여 능동 소나에서는 높은 시간-대역폭곱의 파형들을 사용하며 대표적인 것으로 LFM 펄스를 들 수 있다 LFM 펄스를 사용하여 표적까지의 거리와 표적의 속도를 추정하는 방법으로는 모호함수를 사용하는 방법과 deconvolution 방법 및 FR-기반 기법 등이 있다. 이러한 기법중 모호함수 사용 방법과 deconvolution 방법은 능동 소나의 운용 주파수 대역에서 많은 연산량이 요구되므로 실제 시스템에 적용하기에는 제약을 받는다. 그리고 다른 기법에 비해 적은 연산량을 가지는 FFT-기반 상관관계 기법은 실제 시스템에 적용이 가능하지만 다중경로에 의한 성능 저하를 가지고 있다. 본 논문에서는 적은 연산량을 가지는 FFT-기반 기법을 보완하여 다중경로에 적용 가능한 새로운 탐지기를 제안한다.

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.3E
• /
• pp.12-18
• /
• 2000

Psychoacoustic model based methods have recently been introduced in order to enhance speech signals corrupted by ambient noise. In particular, the perceptual filter is analytically derived where the frequency content of the input noisy signal is made the same as that of the estimated clean signal in auditory domain. However, the analytical derivation should rely on the deconvolution associated with the spreading function in the psychoacoustic model, which results in an ill-conditioned problem. In order to cope with the problem associated with the deconvolution, we propose a novel psychoacoustic model based speech enhancement filter whose principle is the same as the perceptual filter, however the filter is derived by a constrained optimization which provides solutions to the ill-conditioned problem. It is demonstrated with artificially generated signals that the proposed filter operates according to the principle. It is shown that superior performance results from the proposed filter over the perceptual filter provided that a clean speech signal is separable from noise.