• 한국정보기술학회 영문논문지
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• 제9권1호
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• pp.89-102
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• 2019

Collagen can be used in building artificial skin replacements for treatment of burns and towards the reconstruction of bone as well as researching cell behavior and cellular interaction. The strength of collagen in connective tissue rests on the characteristics of collagen fibers. 3D confocal imaging of collagen fibers enables the characterization of their spatial distribution as related to their function. However, the image stacks acquired with confocal laser-scanning microscope does not clearly show the collagen architecture in 3D. Therefore, we developed a new method to reconstruct, visualize and characterize collagen fibers from fluorescence confocal images. First, we exploit the tensor voting framework to extract sparse reliable information about collagen structure in a 3D image and therefore denoise and filter the acquired image stack. We then propose to segment the collagen fibers by defining an energy term based on the Hessian matrix. This energy term is minimized by a min cut-max flow algorithm that allows adaptive regularization. We demonstrate the efficacy of our methods by visualizing reconstructed collagen from specific 3D image stack.

• 한국생산제조학회지
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• 제18권3호
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• pp.248-254
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• 2009

The worn crater wear geometry of coated tools after machining has been configured by using Confocal Laser Scanning Microscopy(CLSM) and the Wavelet-based filtering technique. The CLSM can be well suited to construct the three-dimensional crater wear on the rake surfaces of coated tips. However, The raw heightness data of HEI(height encoded image) acquired by CLSM must be filtered due to the electronic and imaging noise occurring in constructing the crater image. So the Wavelet-based filtering algorithm is necessary to denoise the shape features in a micro scales so as to realize accurate crater wear topography analysis. The crater wear patterns filtered enable us to predict the crater wear shape in order to study the tool wear evolution. The study shows that the technique by combining the CLSM and Wavelet-based filtering is an excellent one to obtain the geometries of worn tool rake surfaces over a wide range of surface resolution in a micro scale.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.398-401
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• 1997

The EMG signal of spinal cord injured patient is very feeble because that the information from central nervous system is not sufficiently transmitted to molter neuron or muscle fiber. Therefore the observer can not observe contraction and relaxation movement of muscle from the raw EMG signal. In this paper, we propose the muscle contraction and relaxation pattern analysis method of spinal cord injured patient whose EMG signal is composed of the sum of motor unit action potential train with additive white Gaussian noise and impulsive noise. From the EMG model, we denoise impulsive noise using median filter which is a kind of nonlinear filter and the output of median filter is transformed to wavelet transform domain for denoising additive white Gaussian noise using threshold level removal technique. As a result, we can obtain the clear contraction and relaxation pattern.

• 한국콘텐츠학회논문지
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• 제14권3호
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• pp.11-21
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• 2014

다중 스케일 영상 분할은 영상 스타일링과 의료진단과 같은 여러 응용에서 매우 중요하다. 이 논문은 다중 스케일 구조를 확보하며 안정적이고 효율적인 MSER에 기반을 둔 새로운 알고리즘을 제안한다. 이 알고리즘은 영상에서 MSER를 수집한 후, 이것들을 특정한 순서대로 영상에 다시 그려 넣음으로써 영상을 분할한다. 영상 경계를 평활화하고 잡음을 제거하기 위한 계층적 모폴로지 연산을 제안한다. 알고리즘의 다중 스케일 특성을 보이기 위해, 여러 종류의 상세 단계 제어의 효과를 영상 스타일링에 적용한다. 제안한 기법은 이러한 효과를 시간이 많이 걸리는 다중 가우시언 평활화없이 수행한다. 분할 품질과 계산 시간 측면에서 민쉬프트-기반 Edison 시스템과 비교 결과를 제시한다.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1771-1776
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• 2020

Adverse effects in the measured gamma spectrum caused by radioactive statistical fluctuations, gamma ray scattering, and electronic noise can be reduced by energy spectrum denoising. Wavelet threshold denoising can be used to perform multi-scale and multi-resolution analysis on noisy signals with small root mean square errors and high signal-to-noise ratios. However, in traditional wavelet threshold denoising methods, there are signal oscillations in hard threshold denoising and constant deviations in soft threshold denoising. An improved wavelet threshold calculation method and threshold processing function are proposed in this paper. The improved threshold calculation method takes into account the influence of the number of wavelet decomposition layers and reduces the deviation caused by the inaccuracy of the threshold. The improved threshold processing function can be continuously guided, which solves the discontinuity of the traditional hard threshold function, avoids the constant deviation caused by the traditional soft threshold method. The examples show that the proposed method can accurately denoise and preserves the characteristic signals well in the gamma energy spectrum.

• 센서학회지
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• 제23권1호
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• pp.7-14
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• 2014

Noncontact electrocardiogram (ECG) measurement using capacitive-coupled technique is a very reliable long-term noninvasive health-care remote monitoring system. It can be used continuously without interrupting the daily activities of the user and is one of the most promising developments in health-care technology. However, ECG signal is a very small electric signal. A robust system is needed to separate the clean ECG signal from noise in the measurement environment. Noise may come from many sources around the system, for example, bad contact between the sensor and body, common-mode electrical noise, movement artifacts, and triboelectric effect. Thus, in this paper, the extended Kalman filter (EKF) is applied to denoise a real-time ECG signal in capacitive-coupled sensors. The ECG signal becomes highly stable and noise-free by combining the common analog signal processing and the digital EKF in the processing step. Furthermore, to achieve ubiquitous monitoring, android-based application is developed to process the heart rate in a realtime ECG measurement.

• 융합신호처리학회논문지
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• 제13권1호
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• pp.26-31
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• 2012

웨이블릿 분해된 최고주파 대역을 4개의 균일대역으로 서브밴드 분할한 후 이 레벨들의 전력값 중에서 최소값과 단조 변환(monotonic transform)을 이용해서 레벨 적응적 경계값을 구하였다. 이 경계값으로 ST(soft threshold) 연산자에 적용하여 고주파 및 중간 대역의 가우시안 잡음을 제거하였다. 그 결과를 VisuShrink 방법 그리고 monotonic 변환 및 가중값을 이용해서 잡음 제거한 결과와 PSNR로 비교하고 이 기법의 실용성을 밝혔다.

• 융합신호처리학회논문지
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• 제15권4호
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• pp.141-147
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• 2014

웨이블릿 축소기법은 웨이블릿 변환 계수의 분산 값에 의해 결정되는 경계값을 이용해서 원신호와 잡음신호 간의 MSE(Mean Square Error)가 최소가 되도록 웨이블릿 변환된 계수를 축소하는 방법이다. 이 논문에서는 단조변환 및 웨이블릿 서브밴드의 전력을 이용해서 고주파 및 저주파 웨이블릿 밴드에 적용되는 새로운 경계값들을 제시하고, 이 값들과 ST(soft-threshold) 연산자에 의해 영상신호에 부가된 가우시안 잡음을 제거하였다. 그리고 그 결과를 VisuShrink방법 및 [15]에서의 제시한 기법의 결과와 PSNR로 비교, 평가하고 이 기법의 실용성을 밝혔다.

• Journal of Information Processing Systems
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• 제16권1호
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• pp.49-60
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• 2020

To solve the edge ringing or block effect caused by the partial differential diffusion in image enhancement domain, a new image enhancement algorithm based on bidirectional diffusion, which smooths the flat region or isolated noise region and sharpens the edge region in different types of defect images on aviation composites, is presented. Taking the image pixel's neighborhood intensity and spatial characteristics as the attribute descriptor, the presented bidirectional diffusion model adaptively chooses different diffusion criteria in different defect image regions, which are elaborated are as follows. The forward diffusion is adopted to denoise along the pixel's gradient direction and edge direction in the pixel's smoothing area while the backward diffusion is used to sharpen along the pixel's gradient direction and the forward diffusion is used to smooth along the pixel's edge direction in the pixel's edge region. The comparison experiments were implemented in the delamination, inclusion, channel, shrinkage, blowhole and crack defect images, and the comparison results indicate that our algorithm not only preserves the image feature better but also improves the image contrast more obviously.

• 한국항공우주학회지
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• 제37권8호
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• pp.767-773
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• 2009

본 논문에서는 웨이블릿 잡음제거 기법 중 하나인 임계화 기법을 이용하여 관성센서 신호의 잡음을 제거하면서도 운동에 의한 신호변화는 상대적으로 왜곡이 적은 필터링기법을 제안하였다. 이는 기존 연구들이 웨이블릿의 장점을 충분히 활용하지 못하고 저역통과 필터와 같은 형태로 사용되기 때문에 급격히 변화하는 항체에 대하여는 부적합한 점을 개선하기 위한 것이다. 제안된 방법의 성능 확인을 위하여 INS-GPS 결합항법 시스템에 적용하였다.