• 한국항행학회논문지
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• 제15권1호
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• pp.83-90
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• 2011

위치인식 기술은 사물이나 사람의 위치를 측정하여 서로 정보를 교환하고 환경을 제어하는데 필요한 핵심기술이다. 현재도 위치인식 기술은 다양한 방법들로 연구되고 있으며, 물류, 의학, 로봇 분야 등에 적용될 수 있다. 그러나 위치인식 기술을 적용하려면 많은 비용이 필요하다. 이에 본 논문에서는 적은 비용으로 구현 가능한 Zigbee기반 AoA 위치인식 시스템을 제안한다. 본 시스템은 흔히 이용하는 스텝 모터, 지향성 안테나, Zigbee 모듈을 사용하여 비컨에 지향성 안테나를 회전시켜 RSSI값을 측정하였다. RSSI값이 가장 큰 값을 가질 때 스텝 모터의 회전각을 계산하여 수신기가 위치한 각도를 판단하고 AoA 방식을 적용하여 수신기의 위치를 측정하였다. 수신기의 위치를 옮겨가며 측정한 결과 35~36cm 정도의 오차가 있었다.

• 한국지능시스템학회논문지
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• 제21권4호
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• pp.442-448
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• 2011

이동 로봇의 위치인식 기술을 위하여 SLAM(Simultaneous Localization and Mapping)에 관한 많은 연구가 진행되고 있다. 본 논문에서는 시야각이 넓은 어안렌즈를 장착한 단일 카메라를 사용하여 천장의 특징점을 이용한 자기위치 인식에 관한 방안을 제시한다. 여기서는 어안렌즈 기반의 비전 시스템이 가지는 왜곡 영상의 보정, SIFT(Scale Invariant Feature Transform) 기반의 강인한 특징점을 추출하여 이전 영상과 이동한 영상과의 정합을 통해 최적화된 영역 함수를 도출하는 과정, 그리고 기하학적 적합모델 설계 등을 제시한다. 제안한 방법을 실험실 환경 및 복도 환경에 적용하여 그 유용성을 확인한다.

• Journal of information and communication convergence engineering
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• 제16권1호
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• pp.6-11
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• 2018

It is important to find the random estimation points in wireless sensor network. A link quality indicator (LQI) is part of a network management service that is suitable for a ZigBee network and can be used for localization. The current quality of the received signal is referred as LQI. It is a technique to demodulate the received signal by accumulating the magnitude of the error between ideal constellations and the received signal. This proposed model accepts any number of random estimation point in the network and calculated its nearest anchor centroid node pair. Coordinates of the LQI sphere are calculated from the pair and are added iteratively to the initially estimated point. With the help of the LQI and weighted centroid localization, the proposed system finds the position of target node more accurately than the existing system by solving the problems related to higher error in terms of the distance and the deployment of nodes.

• Smart Structures and Systems
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• 제30권4호
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• pp.371-383
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• 2022

A novel impact localization method is presented based on impact induced elastic waves in sensorized composite structure subjected to temperature fluctuations. In real practices, environmental and operational conditions influence the acquired signals and consequently make the feature (particularly Time of Arrival (TOA)) extraction process, complicated and troublesome. To overcome this complication, a robust TOA estimation method is proposed based on the times in which the absolute amplitude of the signal reaches to a specific amplitude value. The presented method requires prior knowledge about the normalized wave velocity in different directions of propagation. To this aim, a finite element model of the plate was built in ABAQUS/CAE. The impact location is then highlighted by calculating an error value at different points of the structure. The efficiency of the developed impact localization technique is experimentally evaluated by dropping steel balls with different energies on a carbon fiber composite plate with different temperatures. It is demonstrated that the developed technique is able to localize impacts with different energies even in the presence of noise and temperature fluctuations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.715-722
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• 2012

A structural health monitoring (SHM) technique for locating impact position in a composite plate is presented in this paper. The technique employs a single sensor and spatial focusing properties of time reversal (TR) and inverse filtering (IF). We first examine the focusing effect of back-propagated signal at the impact position and its surroundings through simulation. Impact experiments are then carried out and the localization images are found using the TR and IF signal processing, respectively. Both techniques provide accurate impact location results. Compared to existing techniques for locating impact or acoustic emission source, the proposed methods have the benefits of using a single sensor and not requiring knowledge of material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in the SHM of plate-like structures.

• 로봇학회논문지
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• 제9권2호
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• pp.117-123
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• 2014

Localization is one of the essential tasks necessary to achieve autonomous navigation of a mobile robot. One such localization technique, Monte Carlo Localization (MCL) is often applied to a digital surface model. However, there are differences between range data from laser rangefinders and the data predicted using a map. In this study, commonly observed from air and ground (COAG) features and candidate selection based on the shape of sensor data are incorporated to improve localization accuracy. COAG features are used to classify points consistent with both the range sensor data and the predicted data, and the sample candidates are classified according to their shape constructed from sensor data. Comparisons of local tracking and global localization accuracy show the improved accuracy of the proposed method over conventional methods.

• 전자통신동향분석
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• 제39권4호
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• pp.1-9
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• 2024

As Advanced Air Mobility (AAM) technologies evolve, ensuring accurate navigation and localization in complex urban airspaces has become crucial. Because the Global Navigation Satellite System (GNSS) is prone to vulnerabilities in urban flight environment, an alternative localization technique is required. This paper examines vision-based localization technologies to enhance GNSS-free navigation. In addition, we explore various geo-referencing studies that utilize pre-existing spatial databases to improve the accuracy of vision-based localization under GNSS-denied conditions. This paper discusses the various types of onboard vision camera sensors, vision-based localization, spatial information databases, feature extraction methods, and matching techniques that contribute to the development of a vision-based localization and geo-referencing system for AAM, ensuring safety and reliability in urban operations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.80.2-80
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• 2002

The problem of sound source localization is to determine the position of sound sources using the measurement of the acoustic signals received by microphones. To develop a good sound source localization system which is applicable to a mobile platform such as robots, a time delay estimator with low computational complexity and robustness to background noise or reverberations is necessary. In this paper, an explicit adaptive time delay estimation method for a sound source localization system is proposed. Proposed explicit adaptive time estimation algorithm employs direct adaptation of the delay parameter using a transform-based optimization technique, rather than...

• 제어로봇시스템학회논문지
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• 제19권8호
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• pp.667-675
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• 2013

This paper presents vision-based techniques for underwater landmark detection, map-based localization, and SLAM (Simultaneous Localization and Mapping) in structured underwater environments. A variety of underwater tasks require an underwater robot to be able to successfully perform autonomous navigation, but the available sensors for accurate localization are limited. A vision sensor among the available sensors is very useful for performing short range tasks, in spite of harsh underwater conditions including low visibility, noise, and large areas of featureless topography. To overcome these problems and to a utilize vision sensor for underwater localization, we propose a novel vision-based object detection technique to be applied to MCL (Monte Carlo Localization) and EKF (Extended Kalman Filter)-based SLAM algorithms. In the image processing step, a weighted correlation coefficient-based template matching and color-based image segmentation method are proposed to improve the conventional approach. In the localization step, in order to apply the landmark detection results to MCL and EKF-SLAM, dead-reckoning information and landmark detection results are used for prediction and update phases, respectively. The performance of the proposed technique is evaluated by experiments with an underwater robot platform in an indoor water tank and the results are discussed.

• 한국멀티미디어학회논문지
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• 제15권10호
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• pp.1228-1235
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• 2012

본 논문에서는 웨어러블 컴퓨터 시스템을 위한 WUSB over WBAN 프로토콜에서 요구되는 저전력 소모 위치인식기술로서, 거리 정보를 필요로 하지 않는 위치인식알고리즘을 제안한다. 본 논문에서 제안하는 위치 인식알고리즘은 웨어러블 컴퓨터의 주변 장치를 구성하는 WUSB over WBAN 프로토콜 기반 센서노드에서 독립적으로 실행되어, range-free 한 방법을 사용하여, 각 센서노드의 위치를 신속하게 추정함으로써 전력소모를 최소화한다.