• Communications for Statistical Applications and Methods
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• 제9권1호
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• pp.241-248
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• 2002

The problem of wavelet density estimation based on Shannon's wavelets is studied when the sample observations are contaminated with random noise. In this paper we will discuss the asymptotic normality for deconvolving wavelet density estimator of the unknown density f(x) when courier transform of random noise has polynomial descent.

• The Korean Journal of Applied Statistics
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• 제20권2호
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• pp.323-332
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• 2007

We present a new type of portmanteau test in the frequency domain which is derived from the discrete cosine transform(DCT). For the stationary time series, DCT coefficients are asymptotically independent and their variances are expressed by linear combinations of autocovariances. The covariance matrix of DCT coefficients for white noises is diagonal matrix whose diagonal elements is the variance of time series. A simple way to test the independence of time series is that we divide DCT coefficients into two or three parts and then compare sample variances. We also do this by testing the slope in the linear regression model of which the response variables are absolute values or squares of coefficients. Simulation results show that the proposed tests has much higher powers than Ljung-Box test in most cases of our experiments.

• The Journal of the Acoustical Society of Korea
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• 제15권5호
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• pp.21-29
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• 1996

Industrial equipment, such as power plant, is required to operate reliably, continuously and economically under rather severe conditions of temperature, stress, and enbironment. To test structural integrity and fitness, ultrasonic nondestructive testing is used because of effectiveness and simplicity. In this paper, wavelet transform based least mean square(LMS) algorithm is applied to reduce the influence of the interference occurring between randomly positioned small scatters. The RUN test is performed to check the nonstationarity of the speckle noise signal. The performance of this new approach is compared with that of the time domain LMS algorithm by means of condition numbers, signal-to-noise ratio and 3-D image. As a result, the wavelet transform based LMS algorithm shows better performance than the time domain LMS algorithm in this experiment.

• The KIPS Transactions:PartB
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• 제14B권3호
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• pp.163-170
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• 2007

In autonomous navigation of a mobile vehicle or a mobile robot, localization calculated from recognizing its environment is most important factor. Generally, we can determine position and pose of a camera equipped mobile vehicle or mobile robot using INS and GPS but, in this case, we must use enough known ground landmark for accurate localization. hi contrast with homography method to calculate position and pose of a camera by only using the relation of two dimensional feature point between two frames, in this paper, we propose a method to calculate the position and the pose of a camera using relation between the location to predict through perspective transform of 3D feature points obtained by overlaying 3D model with previous frame using GPS and INS input and the location of corresponding feature point calculated using KLT tracking method in current frame. For the purpose of the performance evaluation, we use wireless-controlled vehicle mounted CCD camera, GPS and INS, and performed the test to calculate the location and the rotation angle of the camera with the video sequence stream obtained at 15Hz frame rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제25권10호
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• pp.1062-1068
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• 2014

In this paper, a novel approach estimating target's rotation velocity(RV) is proposed for inverse synthetic aperture radar(ISAR) cross-range scaling(CRS). Scale invariant feature transform(SIFT) is applied to two sequently generated ISAR images for extracting non-fluctuating scatterers. Considering the fact that the distance between target's rotation center(RC) and SIFT features is same, we can set a criterion for estimating RV. Then, the criterion is optimized through the proposed method based on particle swarm optimization(PSO) combined with exhaustive search method. Simulation results show that the proposed algorithm can precisely estimate RV of a scenario based maneuvering target without RC information. With the use of the estimated RV, ISAR image can be correctly re-scaled along the cross-range direction.

• The Journal of the Korea institute of electronic communication sciences
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• 제13권5호
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• pp.1051-1058
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• 2018

This paper propose image processing algorithm to prevent safety accidents near by subway platform screen door(PSD). First, edges of the subway PSD images are detected and the boundary line between PSD and subway platform is detected to decide people's approach to the PSD using Hough transform. To do this, we draw the boundary line between the PSD and platform, to detect the boundary line and to decide the people's approach to the detected line is completely connected or not. Generally, edge is the basic characteristic of image; thus, edge detection is very important in image processing applications and computer vision area. The conventional edge detection methods such as Roberts, Sobel, Prewitt, and Laplacian etc, which are using a fixed value of mask, and morphological gradient from the structuring element of view and Canny edge detector are widely used. In this paper, we propose the detection algorithm about the people's approach to the subway PSD to prevent the safety accidents by using Canny edge detector and Hough transform and the computer simulation shows the results.

• Kyungpook Mathematical Journal
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• 제52권4호
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• pp.413-431
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• 2012

Let $C^r[0,t]$ be the function space of the vector-valued continuous paths $x:[0,t]{\rightarrow}\mathbb{R}^r$ and define $X_t:C^r[0,t]{\rightarrow}\mathbb{R}^{(n+1)r}$ and $Y_t:C^r[0,t]{\rightarrow}\mathbb{R}^{nr}$ by $X_t(x)=(x(t_0),\;x(t_1),\;{\cdots},\;x(t_{n-1}),\;x(t_n))$ and $Y_t(x)=(x(t_0),\;x(t_1),\;{\cdots},\;x(t_{n-1}))$, respectively, where $0=t_0$ < $t_1$ < ${\cdots}$ < $t_n=t$. In the present paper, using two simple formulas for the conditional expectations over $C^r[0,t]$ with the conditioning functions $X_t$ and $Y_t$, we establish evaluation formulas for the analogue of the conditional analytic Fourier-Feynman transform for the function of the form $${\exp}\{{\int_o}^t{\theta}(s,\;x(s))\;d{\eta}(s)\}{\psi}(x(t)),\;x{\in}C^r[0,t]$$ where ${\eta}$ is a complex Borel measure on [0, t] and both ${\theta}(s,{\cdot})$ and ${\psi}$ are the Fourier-Stieltjes transforms of the complex Borel measures on $\mathbb{R}^r$.

• Journal of Power Electronics
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• 제14권3호
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• pp.564-571
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• 2014

Rotor initial position is an important factor affecting the control performance of electrically excited synchronous motors. This study presents a novel method for estimating rotor initial position based on sliding discrete Fourier transform (sDFT). By injecting an ac excitation into the rotor winding, an induced voltage is generated in stator windings. Through this voltage, the stator flux can be obtained using a pure integral voltage model. Considering the influence from a dc bias and an integral initial value, we adopt the sDFT to extract the fundamental flux component. A quadrant identification model is designed to realize the accurate estimation of the rotor initial position. The sDFT and high-pass filter, DFT, are compared in detail, and the contrast between dc excitation and ac injection is determined. Simulation and experimental results verify that this type of novel method can eliminate the influence of dc bias and other adverse factors, as well as provide a basis for the control of motor drives.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2023년도 학술발표회
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• pp.392-392
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• 2023

통합수자원관리 IWRM(Integrated Water Resources Management)를 위한 다각도의 연구가 진행되고 있다. 구축된 정보의 활용 증진, 정책적 측면 등이 어우러져 고려되어야 비로소 통합으로서의 가치가 확보될 것이다. 본 고에서는 그중 데이터 측면을 살펴본다. 데이터 관점에서도 정보의 수집, 유통, 품질 등 여러 관점의 주제가 존재한다. 예를 들어 유통을 위한 메타데이터는 ISO 19139의 채택에서 추가 보완할 부분이 무엇인지, 유통을 위한 포맷과 인터페이스는 XML과 OGC WFS를 채택시 충분한 호환성이 확보되는지 등 이 주요한 검토요소가 될 것이다. 본 고에서는 이러한 고민에 앞서, 초기 절차인 시스템 적재 과정의 ETL(Extract, Transform and Load)과 ELT(Extract, Load and Transform) 방법을 비교하고자 한다. 수자원 분야 데이터를 사용한 예시 사례를 통하여, 최근 데이터 산업 분야에서 ETL과 ELT 차이가 이슈화되고 있는 이유를 살펴보고, 온프레미스와 클라우드 상황에 대하여 두 가지 방법의 장단점을 비교함으로서 다양한 데이터를 직면하게 되는 IWRM에서의 데이터 적응에 대한 힌트를 얻고자 한다. 기본적으로는 ETL보다 ELT의 효율성이 높을 것으로 전망된다. 그러나 해당 변환 과정이 일회성인지 반복적인지 고려해야 한다. 또한 변환에 있어 지배적인 요소가 변환 프로세스의 복잡도인지, 레코드 건수인지도 유불리에 영향을 준다. 비용측면에서는 ETL보다 ELT의 저장 비용이 증가할 수 있고, 이는 온프레미스 DBMS에서 PaaS 유형의 DBMS로 전환되어감에 따라 더 큰 부담이 될 수 있다. 무엇보다 ETL, ELT에서는 요구되는 변환 기술의 종류가 다르다. 예를 들어 Desktop GIS 도구와 ANSI 표준 SQL 기술로 대표될 수 있으며 각 수행조직에서는 보유 인적자원의 기술 현황과 학습곡선 등을 고려해야 한다. 결론적으로 ETL, ELT의 비교에 있어서는 처리시간과 동시에, 비용과 인적 자원 그리고 전략적 측면도 함께 검토되어야 한다.

• Communications of the Korean Mathematical Society
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• 제32권2호
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• pp.321-332
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• 2017

In this paper, we generalize the extended Appell's and Lauricella's hypergeometric functions which have recently been introduced by Liu [9] and Khan [7]. Also, we aim at establishing some (presumbly) new integral representations and transforms for the extended generalized Appell's and Lauricella's hypergeometric functions.