• Journal of the Korean Statistical Society
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• 제18권2호
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• pp.107-117
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• 1989

A stronger result than that of Park and Marron (1994) is proved here on the asymptotic distribution of the plug-in bandwidth selector. The new result is that the plug-in bandwidth selector may have the rate of convergence ($n^{-4/13}$ with less smoothness conditions on the unknown density functions than as described in Park and Marron's paper. Together with this, a class of various plug-in bandwidth selectors are considered and their asymptotic distributions are given. Finally, some ideas of possible improvements on those plug-in bandwidth selectors are provided.

• Communications for Statistical Applications and Methods
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• 제31권3호
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• pp.337-347
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• 2024

Kernel density estimation is a prevalent technique employed for nonparametric density estimation, enabling direct estimation from the data itself. This estimation involves two crucial elements: selection of the kernel function and the determination of the appropriate bandwidth. The selection of the bandwidth plays an important role in kernel density estimation, which has been developed over the past decade. A range of methods is available for selecting the bandwidth, including the plug-in bandwidth. In this article, the proposed plug-in bandwidth is introduced, which leverages shifted Chebyshev series-based approximation to determine the optimal bandwidth. Through a simulation study, the performance of the suggested bandwidth is analyzed to reveal its favorable performance across a wide range of distributions and sample sizes compared to alternative bandwidths. The proposed bandwidth is also applied for kernel density estimation on real dataset. The outcomes obtained from the proposed bandwidth indicate a favorable selection. Hence, this article serves as motivation to explore additional plug-in bandwidths that rely on function approximations utilizing alternative series expansions.

• Journal of the Korean Statistical Society
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• 제20권1호
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• pp.29-43
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• 1991

Two data-based bandwidth selectors which are optimal in the sense that they achieve n$\^$-$\frac{1}{2}$/ rate of convergence in kernel density estimation are proposed. The proposed bandwidth selectors are constructed by modifying Park and Marron's plug-in method. The first modification is taking Taylor expansion of the mean integrated squared error to two more terms than in the case of plug-in method. The second is estimating more accurately the functionals of the unknown density appeared in the minimizer of the expansion by using higher order kernels. The proposed bandwidth selectors were proved to be optimal in terms of convergence rate. According to small-sample Monte Carlo studies, the proposed bandwidth selectors showed better performance than all the other bandwidth selectors considered in the simulation.

• Communications for Statistical Applications and Methods
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• 제4권2호
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• pp.453-463
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• 1997

Nonparametric kernel regression has recently gained widespread acceptance as an attractive method for the nonparametric estimation of the mean function from noisy regression data. Also, the practical implementation of kernel method is enhanced by the availability of reliable rule for automatic selection of the bandwidth. In this article, we propose a method for automatic selection of the bandwidth that minimizes the asymptotic mean square error. Then, the estimated bandwidth by the proposed method is compared with the theoretical optimal bandwidth and a bandwidth by plug-in method. Simulation study is performed and shows satisfactory behavior of the proposed method.

• International Journal of Advanced Culture Technology
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• 제10권1호
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• pp.236-241
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• 2022

We consider methods of estimating a binary regression function using a nonparametric kernel estimation when there is only one covariate. For this, the Nadaraya-Watson estimation method using single and double bandwidths are used. For choosing a proper smoothing amount, the cross-validation and plug-in methods are compared. In the real data analysis for case study, German credit data and heart disease data are used. We examine whether the nonparametric estimation for binary regression function is successful with the smoothing parameter using the above two approaches, and the performance is compared.

• Communications for Statistical Applications and Methods
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• 제10권2호
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• pp.607-617
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• 2003

This paper offers a practical comparison of efficiency between local likelihood approach and conventional kernel approach in density estimation. The local likelihood estimation procedure maximizes a kernel smoothed log-likelihood function with respect to a polynomial approximation of the log likelihood function. We use two types of data driven bandwidths for each method and compare the mean integrated squares for several densities. Numerical results reveal that local log-linear approach with simple plug-in bandwidth shows better performance comparing to the standard kernel approach in heavy tailed distribution. For normal mixture density cases, standard kernel estimator with the bandwidth in Sheather and Jones(1991) dominates the others in moderately large sample size.

• 디지털융복합연구
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• 제10권4호
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• pp.265-270
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• 2012

최근 기간망의 전송속도는 괄목할 만한 성장을 이루고 있으나 가입자 전송망의 전송속도는 이전 수준에 비교해서 진정이 없는 상태이다. 그래서 가입자 접속 구간은 다수의 LAN과 백본망 사이에 병목지점으로 지적되고 있다. 현재 가입자 구간은 VOD, 양방향게임, 양방향 영상회의와 같은 새로운 대용량 멀티미디어 서비스를 수용하기에 충분한 대역폭을 제공하지 못하고 있다. 그런 가운데 저가의 이더넷 장비와 광선로 인프라를 융합한 EPON(Ethernet Passive Optical Network)이 차세대 가입자 접속망에 가장 적합하다. 하지만 이러한 우수성을 가진 EPON도 안정적인 대용량 멀티미디어 서비스를 제공하기에는 부족함을 가지고 있다. EPON에서 ONU가 수신할 수 있는 대역폭은 1GBPS이지만 송신하기 위한 대역폭은 모든 ONU가 공유해야 하므로 부족하다. 따라서 양방향 초고속 가입자 접속망을 위해 FTTx를 지원하는 EPON의 부족한 상향 전송 대역폭을 충족시키는 상향 대역폭 할당 방법이 필요하다. 본 논문에서는 EPON의 상향 트래픽에 대한 QoS를 보장하기 위한 우선순위 큐를 고려한 가중치 기반의 차등대역폭 할당 방식을 제안한다.

• Communications for Statistical Applications and Methods
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• 제3권1호
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• pp.39-49
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• 1996

비모수적 커널 회귀함수 추정법에서 평활량(bandwidth of smoothing parameter)의 선택은 아주 중요한 문제이다. 교차타당성(cross-validation) 방법에 의한 평활량은 최적평활량으로의 상대적 수렴속도(relative convergence rate)가 $n^{-1/10}$로 상당히 느리다는 것을 알고 있다. 본 연구는 삽입방법(plug-in method)에 의해 선택된 평활량의 상대적 수렴속도가 교차타당성 방법보다 더 빠른 $n^{-2/7}$이 됨을 보였다. 그리고 모의실험을 통하여 소 표본에서도 삽입방법이 교차타당성 방법보다 우수함을 입증하였다.

• 한국정보통신학회논문지
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• 제7권2호
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• pp.228-238
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• 2003

댁내에 이미 가설된 배선이나 무선을 이용하여 저 비용으로 댁내의 정보가전들을 하나의 망으로 연결할 수 있는 HomePNA, HomePlug 또는 HomeRF가 장래 유망한 홈 네트워크 기술이 될 것으로 전망되고 있다. 그러나 HomePNA와 HomePlug는 우선 순위 기법을 이용하여 Class of Service(CoS)만을 제공하며, HomeRF는 실시간 트래픽중 음성만을 고려하여 설계되었기 때문에 홈 네트워크 상의 주요 트래픽인 오디오나 비디오의 QoS를 보장할 수가 없다. 본 논문에서는 홈 네트워크 상에서 QoS를 보장하기 위한 새로운 매체접속제어(Medium Access Control; MAC) 프로토콜을 제안하고, 제안 프로토콜의 프로토타입 구현과 실험을 통한 성능평가를 수행하였다. 소프트웨어 구현을 통한 실험결과 제안 프로토콜은 각 실시간 트래픽별로 대역폭을 할당함으로써 우수한 전송 지연, 지터 그리고 손실의 특성을 가짐을 알 수 있었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.211-215
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• 1997

Localized communication networks for office automation, security monitoring, environmental management of buildings, computer communications, and other applications enjoy every increasing demand. This paper proposes a direct sequence spread spectrum communication system for use in power line data transmission. Advantages of power distribution circuits include reasonably universal coverage and easy access vis a standard wall plug. Disadvantages include limited communication bandwidth, relatively high noise levels, and varying levels of impedance, noise, and attenuation. Spread spectrum signalling provides immunity to narrow-band signal impairments and multiplexing capability. Our prototype power line communication module supports completely physical and data link layers based on the international standard ISO 10368 for reliable high-speed power line communication system. Moreover it provides useful functions to compose a plant monitoring and control system. All the circuits of the communication module are included in one compact circuit. Thus a functional communication system for the power line plant monitoring and control is implemented.