• 한국멀티미디어학회논문지
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• 제22권9호
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• pp.1011-1019
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• 2019

In this paper, we propose a system that can more precisely identify and monitor the position of the tool used in the assembling workplace such as automobile production. The proposed positioning monitoring system is a combination of UWB communication module and MEMS IMU sensor. Since UWB does not need modulation and demodulation function and has low power density, UWB is widely used in indoor positioning field. However, it may cause positioning error due to errors in RF transmission and reception process, which may cause positioning accuracy. Therefore, in this paper, we propose an algorithm that uses IMU as an auxiliary means to compensate for errors that may occur in positioning using only UWB. The tag and anchor of UWB module measure the transmission / reception time by transmitting signals to each other and then estimate the distance between tag and anchor. The MEMS IMU sensor serves to provide positioning calibration information. The tag, which is a mobile node and attached to a moving tool, measures the three-dimensional position of the tool and transfers the coordinate data to the anchor. Thus, it is possible to confirm whether or not the specific tool is properly used according to the prescribed regulations.

• 전기전자학회논문지
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• 제13권1호
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• pp.71-76
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• 2009

As one of the most important requirements for wireless sensor networks, prolonging network lifetime can be realized by minimizing energy consumption in cluster heads as well as sensor nodes. While most of the previous researches have focused on the energy of sensor nodes, we devote our attention to cluster heads because they are most dominant source of power consumption in the cluster-based sensor networks. Therefore, we seek to minimize energy consumption by minimizing the maximum(MINMAX) energy dissipation at each cluster heads. This work requires energy-efficient clustering of the sensor nodes while satisfying given energy constraints. In this paper, we present a constraint satisfaction modeling of cluster-based routing in a heterogeneous sensor networks because mixed integer programming cannot provide solutions to this MINMAX problem. Computational experiments show that substantial energy savings can be obtained with the MINMAX algorithm in comparison with a minimum total energy(MTE) strategy.

• 한국통신학회논문지
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• 제37B권10호
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• pp.889-900
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• 2012

무선 센서 네트워크에서 수신 신호 세기를 이용한 위치추정 방식은 다수의 저전력 노드로 구성된 센서네트워크에 적합한 방법 중의 하나로 고려되고 있다. 수신 신호 세기를 이용한 위치추정 방식의 오차를 줄이기 위해서는 적절한 경로 감쇄 지수 (path-loss exponent, PLE)의 추정이 요구된다. 기존의 위치 추정 방식은 자신의 위치를 알고 있는 각각의 앵커가 인접한 앵커들을 참조하여 PLE를 측정하고, 자신의 위치를 알고자 하는 센서 노드는 수신 신호 세기를 기반으로 가장 인접한 앵커를 판별한 후, 해당 앵커가 측정한 PLE를 자신의 위치 추정에 이용하는 방식을 취하고 있다. 이때의 PLE는 인접한 앵커의 위치에서 측정된 것이기 때문에 실제 측정한 위치에서만 높은 신뢰성을 가지며, 그 외의 위치에서는 다른 값을 갖는 경우가 일반적이다. 따라서 인접한 앵커들을 참조하여 추정한 PLE를 센서 노드의 위치 추정에 직접적으로 이용하는 것은 위치 추정 시 오차를 발생 시키는 주요 원인이 된다. 본 논문에서는 센서 노드 스스로가 각각의 인접한 앵커들에 대한 PLE를 추정하고, 이를 이용하여 센서 노드의 위치를 추정하는 기법을 다루며, 특히, 추정된 센서 노드의 위치에서 각 앵커들까지의 거리를 기반으로 PLE를 반복적으로 재추정하도록 하여 위치 추정 오차를 줄이도록 하는, 반복 PLE 추정을 통한 위치 추정 기법을 제안한다. 성능평가에서는 제안된 기법이 기존의 방법보다 위치 추정 오차를 줄일 수 있음을 보였다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 추계학술발표회 논문집
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• pp.269-274
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• 2004

Recent adoption of the generalized sensor model to IKONOS and Quickbird satellite imagery have promoted various research activities concerning alternative sensor models which can replace conventional physical sensor models. For example, there are the Rational Function Model(RFM), the Direct Linear Transform(DLT) and the polynomial transform. In this paper, the DLT model which uses just a few number of GCPs was suggested. To evaluate the accuracy of the proposed DLT model, the RFM using 35 GCPs and the bias compensation method(Fraser et al., 2003) were compared with it. Quantitative evaluation of 3B positioning results were performed with independent check points and the digital elevation models(DEMs). In result, a 1.9- to 2.2-m positioning accuracy was achieved for modeling and DEM accuracy is similar to the accuracy of the other model methods.

• Journal of Information Processing Systems
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• 제19권3호
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• pp.377-384
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• 2023

The existence of abnormal breakpoint data leads to poor channel balance in wireless sensor networks (WSN). To enhance the communication quality of WSNs, a method for positioning abnormal breakpoint data in WSNs on the basis of signal reconstruction is studied. The WSN signal is collected using compressed sensing theory; the common part of the associated data set is mined by exchanging common information among the cluster head nodes, and the independent parts are updated within each cluster head node. To solve the non-convergence problem in the distributed computing, the approximate term is introduced into the optimization objective function to make the sub-optimization problem strictly convex. And the decompressed sensing signal reconstruction problem is addressed by the alternating direction multiplier method to realize the distributed signal reconstruction of WSNs. Based on the reconstructed WSN signal, the abnormal breakpoint data is located according to the characteristic information of the cross-power spectrum. The proposed method can accurately acquire and reconstruct the signal, reduce the bit error rate during signal transmission, and enhance the communication quality of the experimental object.

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.175-182
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• 2020

This paper introduces a study to estimate the user altitude in need of rescue in an emergency. The altitude is estimated by using the barometric pressure sensor embedded in the smartphone. Compared to GPS, which is degraded in urban or indoor environments, it has the advantage of not having spatial restrictions. With the endless development of smartphone hardware, it is possible to estimate the absolute altitude using the measured value if only the bias of the embedded barometric pressure sensor is applied. The altitude information of the person in need of rescue in an emergency is a great help in reducing rescue time. Since time is tight, we propose online calibration that provides the barometric pressure sensor bias used for altitude estimation through database. Furthermore, experiments were conducted to understand the characteristics of the barometric pressure sensor, which is greatly affected by wind. At the end, the altitude estimation performance was confirmed through an actual field tests in various floors in the building.

• 한국정밀공학회지
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• 제17권12호
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• pp.9-15
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• 2000

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.461-466
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• 1994

This paper is concerned with the positioning control of a flexible arm system using H$_{\infty}$ control theory with optimum sensor location. Firstly, by virtue of the orthogonality of the flexible modes of the flexible arm a reduced order model of the tributed parameter system(DPS) representing the arm has formulated. The dynamical coupling between the flexible arm and DC motor has been considered to formulate an motor composite model. In order to achieve precise positioning with vibration attenuation, sensors have been optimally located. Finally, a robust H$_{\infty}$ controller was designed and the performance of the positioning system has been analyzed.d.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.525-528
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• 2003

In this paper, we present a novel idea to integrate low cost Inertial Measurement Unit(IMU) and Differential Global Positioning System (DGPS) for Telematics applications. As well known, low cost IMU produces large positioning and attitude errors in very short time due to the poor quality of inertial sensor assembly. To conquer the limitation, we present a bimodal approach for integrating IMU and DGPS, taking advantage of positioning and orientation data calculated from CCD images based on photogrammetry and stereo-vision techniques. The positioning and orientation data from the photogrammetric approach are fed back into the Kalman filter to reduce and compensate IMU errors and improve the performance. Experimental results are presented to show the robustness of the proposed method that can provide accurate position and attitude information for extended period for non-aided GPS information.

• 한국통신학회논문지
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• 제40권10호
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• pp.2062-2064
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• 2015

본 논문에서는 LED 패널의 신호를 받아 모바일 단말기에 장착된 이미지 센서를 통하여 임의의 위치에 있는 모바일 단말기의 위치를 추정하는 실내 측위 알고리즘을 제안하였다. 측위 성능평가를 위하여 실내에 존재하는 잡음 환경을 고려하였고, 제안한 알고리즘은 잡음환경에 무관하게 높은 측위 성능을 보임을 입증하였다.