• Communications for Statistical Applications and Methods
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• 제31권1호
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• pp.87-104
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• 2024

Most functional magnetic resonance imaging (fMRI) studies in resting state have assumed that the functional connectivity (FC) between time series from distinct brain regions is constant. However, increased interest has recently been in quantifying possible dynamic changes in FC during fMRI experiments. FC study may provide insight into the fundamental workings of brain networks to brain activity. In this work, we focus on the specific problem of estimating the dynamic behavior of pairwise correlations between time courses extracted from two different brain regions. We compare the sliding-window techniques such as moving average (MA) and exponentially weighted moving average (EWMA), dynamic causality with vector autoregressive (VAR) model, dynamic conditional correlation (DCC) based on volatility, and the proposed alternative methods to use differencing and recursive residuals. We investigate the properties of those techniques in a series of simulation studies. We also provide an application with major depressive disorder (MDD) patient fMRI data to demonstrate studying dynamic correlations.

• 한국컴퓨터정보학회논문지
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• 제23권4호
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• pp.147-153
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• 2018

In this paper, we propose an efficient WBC 14-Diff classification which performs using the WBC-ResNet-152, a type of CNN model. The main point of view is to use Super-pixel for the segmentation of the image of WBC, and to use ResNet for the classification of WBC. A total of 136,164 blood image samples (224x224) were grouped for image segmentation, training, training verification, and final test performance analysis. Image segmentation using super-pixels have different number of images for each classes, so weighted average was applied and therefore image segmentation error was low at 7.23%. Using the training data-set for training 50 times, and using soft-max classifier, TPR average of 80.3% for the training set of 8,827 images was achieved. Based on this, using verification data-set of 21,437 images, 14-Diff classification TPR average of normal WBCs were at 93.4% and TPR average of abnormal WBCs were at 83.3%. The result and methodology of this research demonstrates the usefulness of artificial intelligence technology in the blood cell image classification field. WBC-ResNet-152 based morphology approach is shown to be meaningful and worthwhile method. And based on stored medical data, in-depth diagnosis and early detection of curable diseases is expected to improve the quality of treatment.

• 한국정보통신학회논문지
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• 제23권5호
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• pp.533-539
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• 2019

본 연구는 본 연구는 Microsoft Malware Classification Challenge 데이터 셋을 사용해 임의의 길이 입력 데이터에 대응할 수 있는 멀웨어 분류 모델을 제안한다. 우리는 기존 연구의 멜웨어 데이터를 이미지화 시키는 것을 기반으로 한다. 제안 모델은 멀웨어 데이터가 큰 경우는 많은 이미지를 생성하고, 작은 데이터는 적은 이미지를 생성한다. 생성된 이미지를 시계열 데이터로 Dynamic RNN으로 학습시킨다. RNN의 출력 값은 Attention 기법을 응용해 가장 가중치가 높은 출력만 사용하고, RNN 출력값을 다시 Residual CNN으로 학습시켜 최종적으로 멀웨어를 분류한다. 제안모델을 실험한 결과 검증 데이터 셋에서 Micro-average F1 score 92%를 기록하였다. 실험 결과 특별한 특징 추출 및 차원 축소 없이 임의 길이의 데이터를 학습 및 분류할 수 있는 모델의 성능을 검증할 수 있었다.

• 한국시뮬레이션학회논문지
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• 제16권4호
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• pp.43-55
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• 2007

생산 공정 제어방법들 중에서 이동평균 제어와 지수가중치 이동평균 제어는 가장 널리 사용되는 제어이다. 두 제어는 모두 정확한 제어식을 알고 있다는 전제 하에 최적화된 제어들이다. 이 논문에서는 제어식의 잘못된 예측으로부터 발생하는 문제점에 대해 다루었다. 추정한 모수의 정확도와 가중치 $\lambda$의 범위에 의해 결정되는 각각의 제어방식의 제어한계에 대해서 확인하고 제어 간의 성능을 평가하였다. 또한 잘못 추정된 모델이 존재하는 공정에서 Shift가 발생하였을 때 최적의 제어와 그것을 실제 공정에서 어떻게 적용할지에 대해서 연구하였다. 시뮬레이션을 통해 제안하는 방법의 효용성을 검증하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.759-766
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• 2003

The amount of container freight continuously has been increased. and the low efficiency of container crane causes jamming frequently in transportation and cargo handling at port. The conventional control techniques based on a mathematical model are not well suited for dealing with ill-defined and uncertain systems. Recently. Fuzzy control has been successfully applied to a wide variety of practical problems as robots. automatic train operation system. etc. In this paper. a fuzzy controller for container crane is proposed to accomplish a design of improved control system for minimizing the swing motion at destination. In this scheme a mathematical model for the system is obtained in state space form. Finally. to exhibit the tracking performance and robustness of the proposed controller. computer simulations were carried out with various references, parameter variations and disturbances.

• Structural Engineering and Mechanics
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• 제60권5호
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• pp.875-890
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• 2016

A new structural damage index for seismic fragility analysis of reinforced concrete columns is developed based on a local tensile damage variable of the Lee and Fenves plastic-damage model. The proposed damage index is formulated from the nonlinear regression of experimental column test data. In contrast to the response-based damage index, the proposed damage index is well-defined in the form of a single monotonically-increasing function of the volume weighted average of local damage distribution, and provides the necessary computability and objectivity. It is shown that the present damage index can be appropriately zoned to be used in seismic fragility analysis. An application example in the computational seismic fragility evaluation of reinforced concrete columns validates the effectiveness of the proposed damage index.

• Journal of the Korean Data and Information Science Society
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• 제26권2호
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• pp.525-533
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• 2015

Modern production process is a very complex structure combined observations which are correlated with several factors. When the error signal occurs in the process, it is very difficult to know the root causes of an out-of-control signal because of insufficient information. However, if we know the time of the change, the system can be controlled more easily. To know it, we derive a maximum likelihood estimator (MLE) of the change point in a process when observations are from a multivariate IMA(1,1) process by monitoring residual vectors of the model. In this paper, numerical results show that the MLE of change point is effective in detecting changes in a process.

• 산업경영시스템학회지
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• 제7권10호
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• pp.1-16
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• 1984

The purpose of this paper is to develop rational layout model for small and medium scale industry in Korea. The methodology of this paper is to light the importance of small and medium scale company. Moreover, to overcome the problem of layout in non-massing jobbing production shop this paper is proposed four techniques. So proposed layout model is obtained analytically in single, multiple facility location problem The result of this paper is as follows : First, alternatives to overcome abnormal layout in small and medium company are 1) GT (Group Technology) 2) SLP (Systematic Layout Planning) 3) OR (Operations Research) 4) Computer Second, in single facility location problem, Gradient method and square weighted average method are studied. Lastly in multiple facility location problem, heuristic method is obtained.

• ETRI Journal
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• 제37권4호
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• pp.780-786
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• 2015

This paper describes an audio source separation that is based on nonnegative matrix factorization (NMF) and expectation maximization (EM). For stable and highperformance separation, an effective auxiliary source separation that extracts source residuals and reprojects them onto proper sources is proposed by taking into account an ambiguous region among sources and a source's refinement. Specifically, an additional NMF (model) is designed for the ambiguous region - whose elements are not easily represented by any existing or predefined NMFs of the sources. The residual signal can be extracted by inserting the aforementioned model into the NMF-EM-based audio separation. Then, it is refined by the weighted parameters of the separation and reprojected onto the separated sources. Experimental results demonstrate that the proposed scheme (outlined above) is more stable and outperforms existing algorithms by, on average, 4.4 dB in terms of the source distortion ratio.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.1406-1409
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• 1993

This paper describes a model of the subjective reliability analysis, which uses a fuzzy set, natural language expressions and parameterized operations of fuzzy sets, and reflects analysts' subjectivity. The model has the problem of many different analysis results being obtained since the results depend on their subjectivity. As one of the solutions two kinds of mutual agreements based on the analysis results are considered. One is the intersection and the union of the fuzzy sets obtained by the analysis. The other is the weighted average of the fuzzy sets. This paper gives these interpretations from the viewpoint of system reliability analysis. This paper also shows examples of these considerations.