• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.223-227
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• 2006

본 논문에서는 이동 환경에서 지상파DTV의 Delay Profile의 도출을 위하여 이동 상태에서 필드테스트로 측정된 수신데이터에 포함되어 있는 PN 511(Psuedo Noise)코드를 이용하여 다양한 이동환경에서의 ACF(Auto Correlation Function)값을 도출하였다. 또한, 지역별 대표적인 LOS지역, NLOS지역, 중간지역으로 구분되는 대표적인 세 곳을 선정하여 다양한 이동속도에서의 도출된 ACF값을 통해 최대지연, 평균지연, RMS 지연을 도출하여 이동환경에서의 지상파 DTV의 Delay Profile을 제시하였다.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.107-114
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• 2015

Binary Offset Carrier (BOC) signal planned for future Global Navigation Satellite System (GNSS) provided better positioning accuracy and smaller multipath error than GPS C/A signal. However, due to the multiple side peaks in the auto-correlation function (ACF) of the BOC modulated signals, a receiver may false lock onto one of the side peaks in the tracking mode. This false lock would then result in a fatal tracking error. In this paper, we propose an unambiguous tracking method for composite BOC (CBOC) signals to mitigate this problem. It aims to reduce the side peaks of the ACF of CBOC modulated signals. It is based on the combination of traditional CBOC correlation function (CF) and reference CF of unmodulated pseudo- random noise code (PRN code). First, we present that cross-correlation function (CCF) with unmodulated PRN code is close to the secondary peaks of the traditional CBOC. Then, we obtain an unambiguous correlation function by subtracting traditional CBOC ACF from these CFs. Finally, the tracking performance for the CBOC signals is examined, and it is shown that the proposed method has better performance than the traditional unambiguous tracking method in additive white Gaussian noise (AWGN) channel.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.647-655
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• 2008

This paper presents real-time algorithm for an ultrasonic Local Positioning System(LPS). An ultrasonic LPS consists of 4 transmitters and n receivers. Each transmitter transmits an sequential ultrasonic signal to avoid interference of ultrasonic signal. This method is a noneffective application for a fast object. Because receiver detects four sequential transmissive ultrasonic signal and calculates a position. This paper proposes the method which 4 transmitters transmit simultaneous ultrasonic signal and each transmitter distinguished by frequencies and codes. And Auto-Correlation Function(ACF) method separates codes from an ultrasonic echo signal which is interference of each transmitter's code. If the receiver uses only ACF method, it is difficult to implement real time application for increased computation. This paper implements LPS using dual frequencies and ACF method. Using dual frequencies reduces codes length. The reduced codes length save computation in ACF. To prove this algorithm by experiment, high performance DSP(digital signal processor) used. The result shows the performance of the designed system is good enough positioning.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.987-990
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• 2007

The accuracy of sound strength (G) measurement method in ISO 3382 has been questioned. One of the main reason is the difficulty in measuring a reference sound level in an anechoic chamber with the same set-up which was applied for the actual hall measurements. In the present paper, an in-situ measurement method for G was proposed by investigating the present G measurement method shown in ISO 3382. In addition, the sound radiation characteristics of typical omnidirectional loudspeakers were investigated and Phi (O) of auto correlation function (ACF) parameters was also calculated from an actual music excerpt to characterize the sound energy distribution in concert halls.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.80-88
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• 2003

Radar signal simulation is increasingly gaining in importance according as modem radar systems are more complex. Although computer performance has been advanced, it is difficult to implement the real-time simulation because the detailed model for the radar is necessary to get the desired accuracy. In order to achieve real time operation, we propose radar signal generation technique using ambiguity function, Instead of wellknown correlation method. The ambiguity function is the mathematical modeling of the signal processing procedure which is a simulation section to require the most computations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.510-510
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• 2010

우리나라에서 고속철도는 이미 중요한 대중교통수단 중 하나가 되었으며 향후에도 운행구간을 확대할 예정인 만큼 승객수도 더욱 증가할 것으로 보인다. 또한 승객수가 증가하는 만큼 정숙한 실내환경의 조성 또한 요구되고 있다. 하지만 현재 철도차량 소음에 관한 연구는 대부분 철도 외부에서 방사되는 소음에 한정되어 있으며 철도차량의 내부 소음 특성에 대한 연구는 미비한 상황이다. 현재 국내 환경소음에 대한 규정은 음압레벨만을 기준으로 하고 있지만 실제로 사람이 소음에 대하여 느끼는 청감특성을 나타내기에는 음압레벨만으로는 부족하다. 사람의 청감특성을 효과적으로 반영하기 위하여 음질(Sound Quality)평가의 방법에 대해 현재 활발하게 연구되고 있다. 본 연구에서는 국내에서 운행중인 고속철도 실내 소음의 특성에 대하여 연구하였다. 음압레벨과 loudness의 관계에 대하여 분석하였고 Zwicker parameter과 ACF, IACF 분석을 통하여 객관적인 음질평가를 실시하였다. 또한 청감실험을 통하여 주관적인 음질평가를 수행하여 청감특성에 대하여 분석하고 객관적 평가의 결과를 검증하였다.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.249-255
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• 2016

Since the elderly voices include a lot of noise caused by physiological changes in respiration, phonation, and resonance, the performance of the convergence health-care equipments such as speech recognition, synthesis, analysis program done by elderly voice is deteriorated. Therefore it is necessary to develop researches to operate health-care instruments with elderly voices. In this study, a voice activity detection using a symmetric higher-order differential energy function (SHODEO) was developed and was compared with auto-correlation function(ACF) and the average magnitude difference function(AMDF). It was confirmed to have a better performance than other methods in the voice interval detection. The voice activity detection will be applied to a voice interface for the elderly to improve the accessibility of the smart devices.

• The Journal of the Acoustical Society of Korea
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• v.7 no.4
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• pp.5-12
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• 1988

In order to know the preferred delay time of single reflection in relation in relation to the source signal, and to investigate whether or not there is any display in preference judgment of sound field between subjects of different nationalities, tests of subjective preference for musical sound fields with single reflection were preformed. The result showed that the preferred delay times agreed with the effective duration of auto-correlation function of the source signals, when the amplitude of reflection relative to the direct sound is 0dB. No fundamental disparity in series of judgement of sound field was found even for different series of Judgment with different music motifs. The result of preference test using different passages in single music showed that the fluctuation of the effective duration autocorrelation function over all the passages of the music was small. Thus, the preferred delay time can be determined by the coherence of autocorrelation function of the source signals and the amplitued of reflection.

• Journal of Power Electronics
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• v.5 no.3
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• pp.198-205
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• 2005

The mechanical system of a drive can often be modeled as a two- or three-mass-system. The load is coupled to the driving motor by a shaft able to perform torsion oscillations. For the automatic tuning of the control, it is necessary to know the mathematical description of the system and the corresponding parameters. As the manpower and setup-time necessary during the commissioning of electrical drives are major cost factors, the development of self-operating identification strategies is a task worth pursuing. This paper presents an identification method which can be utilized for the assisted commissioning of electrical drives. The shaft assembly can be approximated as a two-mass non-rigid mechanical system with four parameters that have to be identified. The mathematical background for an identification procedure is developed and some important implementation issues are addressed. In order to avoid the excitation of the system with its natural resonance frequency, the frequency response can be obtained by exciting the system with a Pseudo Random Binary Signal (PRBS) and using the cross correlation function (CCF) and the auto correlation function (ACF). The reference torque is used as stimulation and the response is the mechanical speed. To determine the parameters, especially in advanced control schemes, a numerical algorithm with excellent convergence characteristics has also been used that can be implemented together with the proposed measurement procedure in order to assist the drive commissioning or to achieve an automatic setting of the control parameters. Simulations and experiments validate the efficiency and reliability of the identification procedure.

• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.433-442
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• 2005

An increase In traffic has a large Influence on the performance of a total network. Therefore, traffic management has become an important issue of network management. In this paper, we propose a new routing algorithm that attempts to analyze network conditions using time series prediction models and to propose predictive optimal routing decisions. Traffic congestion is assumed when the predicting result is bigger than the permitted bandwidth. By collecting traffic in real network, the predictable model is obtained when it minimizes statistical errors. In order to predict network traffic based on time series models, we assume that models satisfy a stationary assumption. The stationary assumption can be evaluated by using ACF(Auto Correlation Function) and PACF(Partial Auto Correlation Function). We can obtain the result of these two functions when it satisfies the stationary assumption. We modify routing oaths by predicting traffic in order to avoid traffic congestion through experiments. As a result, Predicting traffic and balancing load by modifying paths allows us to avoid path congestion and increase network performance.