• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.233-236
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• 2004

This paper proposes new method for the enhancement of nonexistent high frequency spectral contents from low sample rate audio signal. For example, Due to the protocol constraint, the audio bandwidth of MP3 is restricted to 16Khz. Although band-restricted MP3 audio provide savings of storage space and network bandwidth, it suffers a major problem of a loss in high frequency fidelity such as localization, ambient information, and bright nature of audio. This paper provides a new mathematical analysis for the adaptive estimation of the high frequency contents based on the nature of the input low sample rate audio. Proposed method can be worked globally to any kind of audio such as speech and music that are restricted by sampling rate and bandwidth.

• 한국군사과학기술학회지
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• 제14권4호
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• pp.590-597
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• 2011

The IDRS provides detection, classification and bearing/range estimation by performing wavefront curvature analysis on an intercepted active transmission from target. Especially, a estimate of the target bearing/range that significantly affects the optimal operation of own submarine is required. Target bearing/range can be estimated by wavefront curvature ranging which use the difference of time arrival at sensors. But estimation ambiguity occur in bearing/range estimation due to a number of peaks caused by high center frequency and limited bandwidth of the intercepted active transmission and distortion caused by noise. As a result the bearing/range estimation performance is degraded. To estimate target bearing/range correctly, bearing/range estimation method that eliminate estimation ambiguity is required. In this paper, therefore, for wavefront curvature ranging, NLS cost function with curve fitting method is proposed, which provide robust bearing/range estimation performance by eliminating estimation ambiguity. Through simulation the performance of the proposed bearing/range estimation methods are verified.

• Journal of Communications and Networks
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• 제15권6호
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• pp.635-644
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• 2013

Adaptive hypertext transfer protocol (HTTP) streaming has become a new trend to support adaptivity in video delivery. An HTTP streaming client needs to estimate exactly resource availability and resource demand. In this paper, we focus on the most important resource which is bandwidth. A new and general formulation for throughput estimation is presented taking into account previous values of instant throughput and round trip time. Besides, we introduce for the first time the use of bitrate estimation in HTTP streaming. The experiments show that our approach can effectively cope with drastic changes in connection throughput and video bitrate.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2000년도 추계학술발표회 논문집
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• pp.65-73
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• 2000

Kernel estimator is very popular in nonparametric density estimation. In this paper we propose an estimator which reduces the bias to the fourth power of the bandwidth, while the variance of the estimator increases only by at most moderate constant factor. The estimator is fully nonparametric in the sense of convex combination of three kernel estimators, and has good numerical properties.

• 한국수학사학회지
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• 제17권2호
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• pp.15-20
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• 2004

본 논문에서는 밀도 추정에 관한 통계량으로서 불편성과 일치성에 관하여 제시하고 밀도함수에 관한 평활 방법으로서 히스토그램과 커널 밀도 추정 및 극소적응평활(local adaptive smoothing)에 관하여 보이고자 한다. 그리고 과거에서 현재까지 비모수 밀도 추정에 관한 연구에 관하여 조사하고 논하고자 한다.

• ETRI Journal
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• 제28권6호
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• pp.822-825
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• 2006

Based on superimposed training methods, a novel time-varying multipath channel estimation scheme is proposed for orthogonal frequency division multiplexing systems. We first develop a linear least square channel estimator, and meanwhile find the optimal superimposed sequences with respect to the channel estimates' mean square error. Next, a low-rank approximated channel estimator is obtained by using the singular value decomposition. As demonstrated in simulations, the proposed scheme achieves not only better performance but also higher bandwidth efficiency than the conventional pilot-aided approach.

• 산업기술연구
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• 제20권B호
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• pp.175-182
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• 2000

In this paper, a novel speed control strategy using an acceleration feedforward compensation by the estimation of the system inertia is proposed. With the proposed method, the enhanced speed control performance can be achieved and the speed response against the disturbance torque can be improved for the vector-controller induction motor drive systems in which the bandwidth of the speed controller cannot be made large enough. The experimental results confirm the validity of the proposed strategy.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 추계학술대회
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• pp.175-176
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• 2018

This paper presents a method to estimate the parameter of permanent magnet synchronous motor using a least squares method. The approximate solution of the linear simultaneous equations is obtained by the pseudoinverse least squares method of the input current and output voltage data of the current controller. It is possible to obtain the current response of the same bandwidth to the general control target by using the Pole-zero Cancellation technique. This paper verifies the performance of the proposed method by comparing the results of estimation of parameters of different motors by simulation.

• 한국통신학회논문지
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• 제31권6C호
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• pp.623-628
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• 2006

본 논문에서는 직교 주파수 분할 다중 (orthogonal frequency division multiplexing: OFDM) 방식의 무선 전송 시스템에서 시간 오차가 (timing error) 존재할 때 주파수 옵셋을 (frequency offset) 추정하는 기법에 대해 다루었다. 시간 오차가 존재하면, 주파수 옵셋 추정식의 상관값이 (correlation value) 감소하게 되어 추정 성능의 감소를 가져온다. 이를 해결하기 위하여, 동기 위상 범위와 문턱값 기반의 주파수 옵셋 추정 기법을 제안하였다. 더불어 이를 기반으로 한 시간 오차 추정기법을 제안하였다. 제안한 기법의 성능을 평가하기 위해서 모의실험을 수행하였고, 제안한 기법이 기존 기법보다 연산 복잡도가 낮으며 시간 오차에 강인함을 확인하였다. 제안한 시간 오차 추정기법은 주파수 옵셋 재 추정에 사용될 수 있으며, 신뢰성 있는 추정값을 제공함을 보였다.

• 조명전기설비학회논문지
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• 제24권7호
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• pp.26-40
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• 2010

We propose a new routing protocol, MCQosR, that is based on bandwidth estimation, admission control, and a routing metric, MCCR - suitable for wireless ad-hoc networks with multiple radios and channels. To use the full capacity of a wireless link, we assume a node with multiple radios for full duplex operation, and a radio using multiple channels to exclude route-intra interference. This makes it possible to use the capacity of a wireless link. Then, to provide bandwidth and delay guarantee, we have a radio with a fixed channel for layer-3 data reception at each node, used to estimate the available bandwidth and expected delay of a wireless link. Based on the estimate of available bandwidth and delay, we apply the call admission control to a new call requiring bandwidth and delay guarantee. New calls with traffic that will overflow link or network capacity are rejected so the accepted calls can use the required bandwidth and delay. Finally, we propose a routing metric, MCCR, which considers the channel contentions and collisions of a wireless link operating in CSMA/CA. MCCR is useful for finding a route with less traffic and distributing traffic over the network to prevent network congestion as much as possible. The simulation of the MCQosR protocol and the MCCR metric shows traffic is distributed and guaranteed service is provided for accepted calls.