• Journal of Biomedical Engineering Research
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• v.19 no.6
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• pp.551-562
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• 1998

Amultiresolution filtering algorithm based on the physical SPECT lesion detachability provides and optimal solution for SPECT reconstruction problem. Related to the previous study, we estimated the SPECT lesion detection capability by m minimum detectable lesion sizes (MDLSs), and generated m reconstruction filters which are designed to maximize the smoothing effect at a fixed MDLS-dependent resolution level $\frac{MDLS}{4\sqrt{2In2}}$. The proposed multiresolution filtering algorithm used a coarse-to-fine approach for the m-level resolution filter images obtained from these m filters for a given projection image. First, the local homogeneity is determined for every pixel of the filter images, by comparing the local variance value computed in a window centered at the pixel and the mode determined from the distribution of the local variances. Based on the local homogeneity, the pixels declared as homogeneous are chosen from the filter image of the lowest resolution, and for the other pixels the same process is repeated for the higher resolution filter images. For the non-homogeneous pixels after this pixels after this repetition process ends, the pixel values of the highest resolution filter image are substituted. From the results of the simulated experiments, the proposed multiresolution filtering algorithm showed a strong smoothing effect in the homogeneous regions and a significant resolution improvement near the edge regions of the projection images, and so produced good adaptability effects in the reconstructed images.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.61-68
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• 2015

In recent times, the median filtering (MF) detector as a forensic tool for the recovery of forgery images' processing history has concerned broad interest. For the classification of MF image, MF detector should be designed with smaller feature set and higher detection ratio. This paper presents a novel method for the detection of MF in altered images. It is transformed from BMP to several kinds of MF image by the median window size. The difference distribution values are computed according to the window sizes and then the values construct the feature set same as the MF window size. For the MF detector, the feature set transformed to the model specification which is computed using latent growth modeling (LGM). Through experiments, the test image is classified by the discriminant into two classes: the true positive (TP) and the false negative (FN). It confirms that the proposed algorithm is to be outstanding performance when the minimum distance average is 0.119 in the confusion of TP and FN for the effectivity of classification.

• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.217-226
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• 2003

Recently Lim has proposed a linear, recursive, unbiased minimum variance filter for a maneuvering target based on the maneuver dynamics modeled as a jump process of Poisson-type. In the proposed filter it was assumed that the state transition parameters of the jump used for target maneuver modeling are a priori known to the filter. However, in most cases they are not known in practice. In this paper, we consider the influence of system (target) modeling error on the performance of the proposed tracking filter arising from the maneuver tracking. For qualitative analysis Monte-Carlo simulations are carried out against employing the maneuver model with different state transition parameters from the actual values.

• Annual Conference on Human and Language Technology
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• 2014.10a
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• pp.95-99
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• 2014

본 논문에서는 최근 급속히 증가하여 사회적 이슈가 되고 있는 SMS 스팸 필터링을 위한 듀얼 SMS 스팸필터링 기법을 제안한다. 지속적으로 증가하고 새롭게 변형되는 SMS 문자 필터링을 위해서는 패턴 및 스팸 단어 사전을 통한 필터링은 많은 수작업을 요구하여 부적합하다. 그리하여 기계 학습을 이용한 자동화 시스템 구축이 요구되고 있으며, 효과적인 기계 학습을 위해서는 자질 선택과 자질의 가중치 책정 방법이 중요하다. 하지만 SMS 문자 특성상 문장들이 짧기 때문에 출현하는 자질의 수가 적어 분류의 어려움을 겪게 된다. 이 같은 문제를 개선하기 위하여 본 논문에서는 슬라이딩 윈도우 기반 N-gram 확장을 통해 자질을 확장하고, 확장된 자질로 그래프를 구축하여 얕은 구조적 특징을 표현한다. 학습 데이터에 출현한 N-gram 자질을 정점(Vertex)으로, 자질의 출현 빈도를 그래프의 간선(Edge)의 가중치로 설정하여 햄(HAM)과 스팸(SPAM) 그래프를 각각 구성한다. 이렇게 구성된 그래프를 바탕으로 노드의 중요도와 간선의 가중치를 활용하여 최종적인 자질의 가중치를 결정한다. 입력 문자가 도착하면 스팸과 햄의 그래프를 각각 이용하여 입력 문자의 2개의 자질 벡터(Vector)를 생성한다. 생성된 자질 벡터를 지지 벡터 기계(Support Vector Machine)를 이용하여 각 SVM 확률 값(Probability Score)을 얻어 스팸 여부를 결정한다. 3가지의 실험환경에서 바이그램 자질과 이진 가중치를 사용한 기본 시스템보다 F1-Score의 약 최대 2.7%, 최소 0.5%까지 향상되었으며, 결과적으로 평균 약 1.35%의 성능 향상을 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2567-2569
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• 2001

본 논문에서는 내이(Inner ear)의 한 부분을 차지하는 Inner Hair Cell을 구현함에 있어 필수적인 요소인 낮은 극점을 갖는 저역통과필터(LPF)를 최소의 면적으로 구현하기 위한 설계방법을 언급한다. 이를 위해 본 논문에서는 CMOS Compatible Lateral BJT (CLBT)를 사용하여 능동소자의 등가 저항을 증가시켜 커패시터의 값을 획기적으로 줄일 수 있는 기법의 LPF와 gm-C필터를 이용한 LPF를 전류모드로 설계하였다. 저전력 특성과 큰 임피던스 특성을 얻기 위해 모든 트랜지스터는 약반전 영역에서 동작하고 극점은 1kHz근처에 존재한다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.948-949
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• 2015

일반적으로 IPMSM의 전압방정식은 d축과 q축이 90도의 위상차를 가지고 있기 때문에 d-q축 간의 상호 인덕턴스를 고려하지 않는다. 하지만 실제로는 d축의 인덕턴스는 q축 전류에 영향을 받으며, 반대로 q축의 인덕턴스도 d축 전류에 영향을 받는다. 따라서 비선형 모델링을 통해 실제 전동기의 형태에 더 가깝게 묘사 하였다. 또한 일반적인 수학식으로 계산하여 Ldq, Lqd를 구해 LPF 필터를 사용하였고 이산적인 최소자승법을 이용한 Gain값을 통해 과도상태에서 더 적합한 LPF와 최소자승법을 비교하는 논문이다.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.1-7
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• 2007

Filter colorimeters have a set of spectral bands for which spectral responsivity is the same as the color matching function defined by CIE (Commission Internationale de I'Eclairage). We have designed a set of color matching function filters denoted by $\bar{x}-filter,\;\bar{y}-filter,\;and\;\bar{z}-filter$. Because the $\bar{x}-function$ has two transmission bands, two $\bar{x}-filters$ are designed to cover the $\bar{x}-function$. To design the filters, we developed a nonlinear least square fit program which determines the thickness of the color glasses by minimizing its spectral mismatch value ($f{_1}'$) to below 3 %. The design has been validated by fabrication of the $\bar{y}-bar$ filter, of which $f{_1}'$ was measured to be 2.8 %. Considering a LCD flat panel display as a device under test, we have calculated the systematic error of the colorimetric measurement using the designed filters.

• Science of Emotion and Sensibility
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• v.25 no.1
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• pp.67-78
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• 2022

Interest in bio-signal monitoring of wearable devices is increasing significantly as the next generation needs to develop new devices to dominate the global market of the information and communication technology industry. Accordingly, this research developed a resistive textile strain sensor through a wetting process in a single-wall carbon nanotube dispersion solution using an E-Band with low hysteresis. To measure the resistance signal in the E-Band to which electrical conductivity is applied, a universal material tester, an Arduino, and LCR meters that are microcontroller units were used to measure the resistance change according to the tensile change. To effectively handle various noises generated due to the characteristics of the fabric textile strain sensor, the filter performance of the sensor was evaluated using the moving average filter, Savitsky-Golay filter, and intermediate filters of signal processing. As a result, the reliability of the filtering result of the moving average filter was at least 89.82% with a maximum of 97.87%, and moving average filtering was suitable as the noise filtering method of the textile strain sensor.

• Journal of Advanced Navigation Technology
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• v.1 no.1
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• pp.11-22
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• 1997

Determination of position, velocity and time from the satellite signals is the central problem of the GPS receiver. Generally, GPS receiver uses least square method for navigation filter algorithm. The Kalman filter has known as an optimal linear estimator, which uses the knowledge of the system dynamics and the statistical characteristics of the system noises and measurement error. In this paper, we design an 8 state Kalman filter for GPS navigation and employ some techniques that can reduce computational burden, increase numerical stability, and improve filtering performance. To show its effectiveness, the designed filter is implemented in a GPS receiver and tested in real-time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1113-1120
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• 2017

As the size of the data is getting larger and larger due to improvement of the telecommunication techniques, it would be main issues to develop and process the database. The bloom filter used to lookup a particular element under the given set is very useful structure because of the space efficiency. In this paper, we analyse the main factor of the false positive and propose the new parallel type bloom filter in order to minimize the false positive which is caused by other hash functions. The proposed method uses the memory as large as the conventional bloom filter use, but it can improve the processing speed using parallel processing. In addition, if we use the perfect hash function, the insertion and deletion function in the proposed bloom filter would be possible.