• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.763-766
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• 2000

본 논문에서는 해저 고정형 선배열센서를 이용하여 다중경로 신호를 이용한 근거리표적의 위치 추정 알고리즘을 제안하였다. 다중경로를 통하여 근거리 표적의 신호가 센서에 도달하는 경우 각 신호의 원추각이 다르므로 신호들의 원추각과 시간차를 추정해서 3차원 표적의 위치를 추정할 수 있다. 원거리표적으로 가정하고 추정한 원추각과 신호들의 시간차에 대한 관계식을 유도하였으며 이들을 연립하여 표적의 위치를 추정하였다. 그러나 표적이 위치한 기하학적인 위치에 따라 신호들의 원추각이 거의 같아지는 지점이 존재한다. 이 경우 부가적인 1차원 탐색으로 표적의 위치를 추정하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1125-1132
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• 2005

Ultra-wideband (UWB) ranging poses a set of time delay estimation problems for designers. The possibility of a large error can be a challenging problem for accurate ranging and positioning. An approximate analysis of large error performance of UWB ranging in multipath and multiuser environments is posed. Both analytical and experimental approaches are taken to evaluate the large error variance in a correlation-based serial search scenario.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.109-120
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• 2004

Since the late of 1990, there have been number of studies on the required number of probe vehicles and/or optimal aggregation interval sizes for travel time estimation and forecasting. However, in general one to five minutes are used as aggregation intervals for the travel time estimation intervals for the travel time estimation and/or forecasting of loop detector system without a reasonable validation. The objective of this study is to deveop models for identifying optimal aggregation interval sizes of loop detector data for travel time estimation and prediction. This study developed Cross Valiated Mean Square Error (CVMSE) model for the link and route travel time forecasting, The developed models were applied to the loop detector data of Kyeongbu expressway. It was found that the optimal aggregation sizes for the travel time estimation and forecasting are three to five minutes and ten to twenty minutes, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.65-70
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• 2005

Incorrect ambiguity integer of GPS make a large error on attitude determination. In this paper one method is suggested for estimating the multipath of GPS carrier measurement while attitude determination. The multi-antenna system consists of 4 antennas have the same clock error help to make attitude determination effectively. If the distance between antennas is a half wavelength, it is not necessary to search the ambiguity integer and the multipath of GPS carrier measurement can be estimated. The results of the simulation are shown and analyzed.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.145-153
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• 2008

Existing shortest-path algorithms mainly consider a single attribute. But traveler actually chooses a route considering not single attribute but various attributes which are synthesized travel time, route length, personal preference, etc. Therefore, to search the optimal path, these attributes are considered synthetically. In this study route searching algorithm which selects the maximum utility route using discrete choice model has developed in order to consider various attributes. Six elements which affect route choice are chosen for the route choice model and parameters of the models are estimated using survey data. A multinomial logit models are developed to design the function of route choice model. As a result, the model which has route length, delay time, the number of turning as parameter is selected based on the significance test. We use existing shortest path algorithm, which can reflect urban transportation network such as u-turn or p-turn, and apply it to the real network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1468-1476
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• 1997

In mobile communication systems, the Reduced State Sequence Estimation(RSSE) receiver must be able to track changes in the channel. This is carried out by the adaptive channel estimator. However, when the tentative decisions are used in the channel estimator, incorrect decisions can cause error propagation. This paper presents a new channel estimator using the path history in the Viterbi decoder for preventing error propagation. The selection of the path history in the Viterbi decoder for preventing error propagation. The selection of the path history for the channel estimator depends on the path metric as in the decoding of the Viterbi decoder in RSSE. And a discussion on the channel estimator with different adaptation algorithms such as Least Mean Square(LMS) algorithm and Recursive Least Square(RLS) algorithm is provided. Results from computer simulations show that the RSSE receivers using the proposed channel estimator have better performance than the other conventional RSSE receiver, and that the channel estimator with RLS algorithm is adequate for multipath fading channel.

• The Journal of the Acoustical Society of Korea
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• v.34 no.5
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• pp.377-384
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• 2015

An active noise control (ANC) algorithm for noise canceling headphone is proposed. In this study, the feedback ANC operated with the filtered-x least mean square algorithm (FxLMS) algorithm is used to attenuate the undesired noise. Also an adaptive residual music canceller (RMC) is proposed for enhancing the accuracy of the reference signal of the feedback ANC. Simulation results show that a high quality of music sound can be consistently achieved in a time-varying secondary path situation.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.121-122
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• 2008

본 논문에서는 2차 경로의 추정을 통하여 안정성이 강화된 능동소음 제어 시스템을 제안한다. LMS 알고리즘은 구조가 단순하고 계산량이 적은 장전이 있지만, 광대역 소음원에 적용할 경우 수렴 성능이 좋지 않은 단점이 있으며, 2차 경로 및 소음원 입력의 파워가 시변 할 경우 적응 알고리즘의 안정성이 약화되는 문제점이 발생한다. 본 논문에서는 지속적으로 누적 오차를 추적하여 일정 값 이상으로 증가하면 자동적으로 2차 경로 전달함수를 새로 추정하는 자동오프라인 추정 기법을 제안하였다. 공조용 덕트에 광대역 소음을 적용하여 제안된 능동소음제어 시스템을 실험을 수행한 결과 우수한 특성을 얻었다.

• The Journal of the Acoustical Society of Korea
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• v.21 no.8
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• pp.686-694
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• 2002

This paper proposes an algorithm for estimating positions of array elements placed on a sea floor using acoustic signal in multipath ocean environment. The positions of array elements are estimated by using the travel times of m-sequence signal influenced by the multi-paths environment. The horizontal distance between source and receiver calculated based on the ray model. The proposed paper the algorithm is verified by both simulation data and field experiment in the Bast Sea.

• Journal of Korean Society of Transportation
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• v.31 no.3
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• pp.45-54
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• 2013

Korea Expressway Corporation has been utilizing vehicles equipped with dedicated short range communication (DSRC) based on-board equipment (OBE) for collecting path travel times. A path based method (PBM) estimates the path travel time using probe vehicles traveling whole links on the path, so it is not always possible to obtain sufficient samples for calculating path travel time in the DSRC system. Having this problem in utilizing DSRC for travel time information, this study attempted to estimate path travel time with the help of a link based method (LBM) and examined whether the LBM can be used for obtaining reliable path travel times. Some comparisons were made and identified that the MAPE difference between the LBM and the PBM estimates are less than 3%, signaling that LBM can be used as a proxy for PBM in case of sparse sample conditions. Some limitations and a future research agenda have also been proposed.