• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2552-2554
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• 2005

제어기 설계에서 이득여유와 위상여유는 견실성 및 안정도 판별의 중요한 척도로 사용되며, 그 중 위상여유는 시스템의 성능지수와 관련된다. 이와 같은 이유로 이득여유와 위상여유의 안정도를 고려한 제어기의 설계방법이 연구되어지고 있다. 근래 Weng Khuen Ho와 Chang Chieh Hang이 제안한 설계방법은 복잡한 계산을 필요로 하는 arctan 함수를 1차 선형함수로 근사화 하여 복잡도를 감소시키면서도 원하는 이득여유와 위상여유를 만족시키는 제어기의 파라미터를 찾았다. 하지만 이 방법은 실제의 arctan 함수를 사용하는 것이 아니라 근사화된 수식을 사용함으로써 오차가 수반되어 원하는 설계조건을 만족 하지 못한다. 따라서 본 논문은 이러한 오차를 최소화하기 위해서 최적화 알고리즘을 이용한 이득여유와 위상여유를 보상하는 PID 제어기를 설계하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.610-614
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• 2006

In this paper the advanced method of geodesic active contours was developed for the task of building detection from aerial and satellite images. Automatic extraction of man-made structures including buildings, building blocks or roads from remote sensing data is useful for land use mapping, scene understanding, robotic navigation, image retrieval, surveillance, emergency management procedures, cadastral etc. A level set method based on a region-driven segmentation model was implemented with which building boundaries were detected, through this curve propagation technique. The essence of this approach is to optimize the position and the geometric form of the curve by measuring information along that curve, and within the regions that compose the image partition. To this end, one can consider uniform intensities inside objects and the background. Thus, given an initial position of the curve, one can determine global, region-driven functions and provide a statistical description of the inside and outside object area. The calculus of variations and a gradient descent method was used to optimize the variational functional by an iterative steady state process. Experimental results demonstrate the potential of the proposed processing scheme.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2254-2259
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• 2005

In this paper, we propose a wavelet based fuzzy neural network(WFNN) based direct adaptive control scheme for the solution of the tracking problem of mobile robots. To design a controller, we present a WFNN structure that merges advantages of neural network, fuzzy model and wavelet transform. The basic idea of our WFNN structure is to realize the process of fuzzy reasoning of wavelet fuzzy system by the structure of a neural network and to make the parameters of fuzzy reasoning be expressed by the connection weights of a neural network. In our control system, the control signals are directly obtained to minimize the difference between the reference track and the pose of mobile robot using the gradient descent(GD) method. In addition, an approach that uses adaptive learning rates for the training of WFNN controller is driven via a Lyapunov stability analysis to guarantee the fast convergence, that is, learning rates are adaptively determined to rapidly minimize the state errors of a mobile robot. Finally, to evaluate the performance of the proposed direct adaptive control system using the WFNN controller, we compare the control performance of the WFNN controller with those of the FNN, the WNN and the WFM controllers.

• 제어로봇시스템학회논문지
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• 제16권12호
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• pp.1220-1225
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• 2010

This paper proposes a novel active noise control (ANC) approach that uses an IIR filter and neural network techniques to effectively reduce interior noise. We construct a multiple-channel IIR filter module which is a linearly augmented framework with a generic IIR model to generate a primary control signal. A three-layer perceptron neural network is employed for establishing a secondary-path model to represent air channels among noise fields. Since the IIR module and neural network are connected in series, the output of an IIR filter is transferred forward to the neural model to generate a final ANC signal. A gradient descent optimization based learning algorithm is analytically derived for the optimal selection of the ANC parameter vectors. Moreover, re-estimation of partial parameter vectors in the ANC system is proposed for online learning. Lastly, we present the results of a numerical study to test our ANC methodology with realistic interior noise measurement obtained from Korean railway trains.

• 한국음향학회지
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• 제14권1호
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• pp.22-30
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• 1995

본 논문은 입력 신호가 복수 정현파(multiple sinusoids) 신호로 구성되고 측정 잡음이 가우시안일 때 최소평균사승(least mean fourth : LMF) 알고리듬의 수렴 특성을 새로운 해석 기법을 적용하여 이론적으로 분석하였다. LMF알고리듬은 오차 신호의 4승을 비용 함수(cost function)로 하여 gradient-descent 방법으로 구한 적응 알고리듬인데 기존 Walach 와 Widrow의 수렴 특성 분석에서는 이루어지지 않았던 계수 추정 오차에 대한 2차 모멘트의 과도기 상태 수렴 특성을 본 논문에서 새로이 제시하였다. 결론적으로 가우시안 측정 잡음의 분산과 수렴 상수의 크기에 따라 서로 다른 수렴 특성을 나타냄을 알 수 있었다. 이러한 결과는 기존 Walach 와 Widrow의 분석 기법으로서는 알 수가 없었다.

• 한국컴퓨터정보학회논문지
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• 제23권7호
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• pp.81-90
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• 2018

In this paper, reducing lense Vignetting effect and adaptive learning rate method are proposed to complement Scribner's neural network for nuc algorithm which is the effective algorithm in statistic SBNUC algorithm. Proposed reducing vignetting effect method is updated weight and bias each differently using different cost function. Proposed adaptive learning rate for updating weight and bias is using sobel edge detection method, which has good result for boundary condition of image. The ordinary statistic SBNUC algorithm has problem to compensate lense vignetting effect, because statistic algorithm is updated weight and bias by using gradient descent method, so it should not be effective for global weight problem same like, lense vignetting effect. We employ the proposed methods to Scribner's neural network method(NNM) and Torres's reducing ghosting correction for neural network nuc algorithm(improved NNM), and apply it to real-infrared detector image stream. The result of proposed algorithm shows that it has 10dB higher PSNR and 1.5 times faster convergence speed then the improved NNM Algorithm.

• 말소리와 음성과학
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• 제7권4호
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• pp.77-83
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• 2015

Voice complication without the laryngeal nerve injury can occur after thyroidectomy. The purpose of this study is to investigate voice changes according to extent of thyroidectomy with acoustic analysis. Thirty-five female patients with papillary thyroid carcinoma took voice evaluation at before and 1 month, and 3 months after thyroidectomy. Acoustic analysis parameters were speaking fundamental frequency(SFF), min $F_0$, max $F_0$, dynamic range $F_0$, jitter, shimmer, noise-to-harmonic ratio(NHR), and Cepstral prominence peak(CPP). Repeated-measured analysis of variance was applied. Time-related voice changes showed significant differences in all parameters except NHR. At 1 month after surgery, voice quality was worse and pitch was decreasing, but voice quality and pitch were improving at 3-month follow-up. Voice changes according to the extent of surgery were in SFF, max $F_0$, and dynamic range $F_0$. Time by surgery-related voice change existed only in min $F_0$. The result showed that the severity of voice complication depended on the extend of thyroidectomy which had a negative impact on $F_0$-related parameters. The deterioration of voice quality at 1 month after thyroidectomy may be affected by the loss of thyroid hormone in the blood. The descent of $F_0$-related parameters may be impacted by laryngeal fixation of surgical site adhesion.

• 한국지능시스템학회논문지
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• 제11권5호
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• pp.413-418
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• 2001

본 논문에서는 기존에 사용한 물리적 카메라 모델 대신 퍼지 모델을 사용한 새로운 카메라 보정 방식을 제안한다. 카메라 보정은 카메라의 영상 좌표계와 실제 환경이 가지는 좌표계와의 관계를 규정하는 것으로, 퍼지 모델을 이용하는 방법은 기존의 방법에서 이용했던 물리적 변수들을 설정할 수는 없지만 카메라 보정의 목적인 카메라 좌표계와 실제 환경 좌표계와의 관계를 별다른 제약없이 규정할 수 있으므로 매우 간단하고 효율적인 카메라 보정 방법이다. 실제 실험을 통해 얻은 실공간상의 하나의 보정면 좌표에 대해 퍼지 모델링 방법을 이용하여 3차원 실 공간 좌표 및 2차원 영상좌표 예측을 통해 제안한 방법의 유효성을 보인다.

• 한국한의학연구원논문집
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• 제10권1호
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• pp.63-80
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• 2004

The Sasang constitution food is classified by Sadang theory(四黨論), Aroma-Scent-Fluid-Taste(馨臭液味), Inhale-Exhale-Incomings-Outgoings(呼吸出納), Ascent-Descent-Open-Close(升降開闔), Healthy Energy(保命之主), which is different from the Oriental medicine herb classification of traditional oriental medicine. So, we obtained the result of the characteristic of radish, one of much used food materials by examining ancient documents as follows. First, today 'Rae(來)' is used as to come' but in ancient days, was used as 'wheat'. Radish(萊服) is the word made by meaning which removes and overcomes the poison of wheat Second, Ancient people realized the power of its Inhale Disperse Qi (呼散之氣) when the root of radish raises quickly from the soil, and recognized that radish has such a good dissolving function when seeing Bean-curd becomes soft if radish is added to Bean-curd dish. That’s why they classified that radish is lung medicine, and used it as Taeumin type medicine. So if someone is suffocated by the smoke and has indigestion, chronic asthmatic coughing, now we use radish by applying the Inhale Disperse Qi of radish.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2209-2211
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• 2004

Unlike the wavelet neural network, since a mother wavelet layer of the self-recurrent wavelet neural network (SRWNN) is composed of self-feedback neurons, it has the ability to store past information of the wavelet. Therefore we propose the prediction method for the nonlinear chaotic time series model using a SRWNN. The SRWNN model is learned for the modeling of a function such that the inputs arc known values of the time series and the output is the value in the future. The parameters of the network are tuned to minimize the difference between the nonlinear mapping of the chaotic time series and the output of SRWNN using the gradient-descent method for the adaptive backpropagation algorithm. Through the computer simulations, we demonstrate the feasibility and the effectiveness of our method for the prediction of the logistic map and the Mackey-Glass delay-differential equation as a nonlinear chaotic time series.