• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.569-572
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• 1999

In this paper we present a color image segmentation algorithm based on statistical models. A novel deterministic annealing Expectation Maximization(EM) formula is derived to estimate the parameters of the Gaussian Mixture Model(GMM) which represents the multi-colored objects statistically. The experimental results show that the proposed deterministic annealing EM is a global optimal solution for the ML parameter estimation and the image field is segmented efficiently by using the parameter estimates.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.529-531
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• 2001

We present an expectation-maximization algorithm for principal component analysis via orthogonalization. The algorithm finds actual principal components, whereas previously proposed EM algorithms can only find principal subspace. New algorithm is simple and more efficient thant probabilistic PCA specially in noiseless cases. Conventional PCA needs computation of inverse of the covariance matrices, which makes the algorithm prohibitively expensive when the dimensions of data space is large. This EM algorithm is very powerful for high dimensional data when only a few principal components are needed.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.103-106
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• 2002

본 논문에서는 입력음성신호로부터 음소간의 경계를 찾는 문제를 풀기위해 재귀적인 방식으로 EM 알고리즘을 적용한다. 즉, 예상되는 두 끝점 사이의 부분을 현재의 프레임 n 이라고 하면, 그 전 프레임 n-1 에서 구해진 끝점이 주는 정보와 그 끝점으로부터 이어지는 음성샘플로부터 현재 프레임의 끝점을 구한다. 또한 현재의 프레임 n 에서 끝점을 추정해 내면, 그 추정한 끝점과 그 점 이후에 이어지는 음성샘플값으로부터 다음 프레임 n+1 의 끝점을 구한다. 이러한 방식을 재귀적인 음소분리 방식이라고 한다. 그리고, 각 프레임에서 끝점을 구하기 위해서는 끝점의 좌표를 추정해야 할 파라메터로 하고, 그 주변의 음성샘플 값을 관찰 값으로 하여 EM(Expectation and Maximization) 알고리즘을 이용한다. 이 EM 알고리즘을 이용한 재귀적인 음소분리 방식을 실제 음성 DB 로부터 음소쌍을 추출하여 테스트 했을 때 약 5 회의 EM 반복 후에 경계간으로 수렴함을 볼 수 있었다.

• 대한핵의학회:학술대회논문집
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• 2000.05a
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• pp.84-84
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• 2000

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.719-724
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• 1996

본 연구는 유지, 보수되는 상시 작동 시스템에 대한 신뢰성 분석을 위해 동적 불완전 수리모형 및 분석 절차의 개발을 수행하였다. 또한 수리 상태에 대한 데이타가 완전히 잠재적(masked)이라 하더라도 기본 분포(base-line distribution)가 와이블 분포라는 가정하에 모수적 추정 절차를 개발하였다. 개발된 추정 절차는 기본적으로 EM(Expectation and Maximization : EM) 알고리즘의 틀(framework)을 유지하고 있다. 특히 최소 수리 특성으로 인해 분포가 변화함에 따라 발생하는 추정의 어려움을 해결하기 위해 데이타 변환(transformation)식을 제시하고 이러한 변환 데이타를 사용함으로써 추가적 데이타의 요구없이 잠재적 데이타를 사용하여 추정을 가능하게 하는 모수 추정 알고리즘을 제시하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.360-362
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• 1998

In the original mixtures of experts framework, the parameters of the network are determined by gradient descent, which is naturally slow. In [2], the Expectation-Maximization(EM) algorithm is used instead, to obtain the network parameters, resulting in substantially reduced training times. This paper presents the new EM algorithm for prediction. We show that an Efficient training algorithm may be derived for the HME network. To verify the utility of the algorithm we look at specific examples in time series prediction. The application of the new EM algorithm to time series prediction has been quiet successful.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.405-406
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• 2006

This paper proposes the new algorithm for the extraction of the corresponding points. Our algorithm is based on RANSAC(Random Sample Consensus) with EM(Expectation-Maximization). In the procedure of RANSAC, N-points are selected by the result of EM instead of the random selection. EM+SAC algorithm is applied to the correspondence for the mosaicing.

• Structural Engineering and Mechanics
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• v.63 no.6
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• pp.809-824
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• 2017

The accurate evaluation of wind characteristics and wind-induced structural responses during a typhoon is of significant importance for bridge design and safety assessment. This paper presents an expectation maximization (EM) algorithm-based angular-linear approach for probabilistic modeling of field-measured wind characteristics. The proposed method has been applied to model the wind speed and direction data during typhoons recorded by the structural health monitoring (SHM) system instrumented on the arch Jiubao Bridge located in Hangzhou, China. In the summer of 2015, three typhoons, i.e., Typhoon Chan-hom, Typhoon Soudelor and Typhoon Goni, made landfall in the east of China and then struck the Jiubao Bridge. By analyzing the wind monitoring data such as the wind speed and direction measured by three anemometers during typhoons, the wind characteristics during typhoons are derived, including the average wind speed and direction, turbulence intensity, gust factor, turbulence integral scale, and power spectral density (PSD). An EM algorithm-based angular-linear modeling approach is proposed for modeling the joint distribution of the wind speed and direction. For the marginal distribution of the wind speed, the finite mixture of two-parameter Weibull distribution is employed, and the finite mixture of von Mises distribution is used to represent the wind direction. The parameters of each distribution model are estimated by use of the EM algorithm, and the optimal model is determined by the values of $R^2$ statistic and the Akaike's information criterion (AIC). The results indicate that the stochastic properties of the wind field around the bridge site during typhoons are effectively characterized by the proposed EM algorithm-based angular-linear modeling approach. The formulated joint distribution of the wind speed and direction can serve as a solid foundation for the purpose of accurately evaluating the typhoon-induced fatigue damage of long-span bridges.

• Journal of Gastric Cancer
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• v.14 no.4
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• pp.259-265
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• 2014

Purpose: Survival analysis of gastric cancer patients requires knowledge about factors that affect survival time. This paper attempted to analyze the survival of patients with incomplete registered data by using imputation methods. Materials and Methods: Three missing data imputation methods, including regression, expectation maximization algorithm, and multiple imputation (MI) using Monte Carlo Markov Chain methods, were applied to the data of cancer patients referred to the cancer institute at Imam Khomeini Hospital in Tehran in 2003 to 2008. The data included demographic variables, survival times, and censored variable of 471 patients with gastric cancer. After using imputation methods to account for missing covariate data, the data were analyzed using a Cox regression model and the results were compared. Results: The mean patient survival time after diagnosis was $49.1{\pm}4.4$ months. In the complete case analysis, which used information from 100 of the 471 patients, very wide and uninformative confidence intervals were obtained for the chemotherapy and surgery hazard ratios (HRs). However, after imputation, the maximum confidence interval widths for the chemotherapy and surgery HRs were 8.470 and 0.806, respectively. The minimum width corresponded with MI. Furthermore, the minimum Bayesian and Akaike information criteria values correlated with MI (-821.236 and -827.866, respectively). Conclusions: Missing value imputation increased the estimate precision and accuracy. In addition, MI yielded better results when compared with the expectation maximization algorithm and regression simple imputation methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.721-727
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• 2016

In this paper, in order to resolve the problem of reduction for D2D (device to device) advertisement dissemination efficiency of conventional dissemination algorithms, we here propose several clustering algorithms (modified single linkage algorithm (MSL), K-means algorithm, and expectation maximization algorithm with Gaussian mixture model (EM)) based advertisement dissemination algorithms to improve advertisement dissemination efficiency in D2D communication networks. Target areas are clustered in several target groups by the proposed clustering algorithms. Then, D2D advertisements are consecutively distributed by using a routing algorithm based on the geographical distribution of the target areas and a relay selection algorithm based on the distance between D2D sender and D2D receiver. Via intensive MATLAB simulations, we analyze the performance excellency of the proposed algorithms with respect to maximum number of relay transmissions and D2D user density ratio in a target area and a non-target area.