• 한국정밀공학회지
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• 제25권10호
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• pp.122-129
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• 2008

This paper deals with precise positioning of a high-speed positioning stage without inducing residual vibration by using an input shaping technique. Input shaping is well known to be a very effective tool for suppressing the residual vibration of flexible structures. However, the ordinary input shaping for positioning stages is designated mostly for velocity regulation, not for the residual vibration at the target position. The main difficulties in implementing input shaping along with precise positioning are the time delay caused by the servo system characteristics and the s-curve feature often employed in some motor controllers. This paper analyzes the dynamic responses of a single-mode-dominate stage system subjected to input shaping. A theoretical model is developed io investigate the nature of system. In order to overcome the difficulty, this paper proposes an improved input shaper based on modified command profile generation. The proposed method is proved effective through experiments and simulations.

• 반도체디스플레이기술학회지
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• 제22권2호
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• pp.50-55
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• 2023

Due to the unavailability of global positioning system (GPS) indoors, various indoor pedestrian positioning methods have been designed to estimate the position of the user using received signal strength (RSS) measurements from radio beacons, such as wireless fidelity (WiFi) access points and Bluetooth low energy (BLE) beacons. In indoor environments, radio-frequency (RF) signals are unpredictable and change over space and time because of multipath associated with reflection and refraction, shadow fading caused by obstacles, and interference among different devices using the same frequencies. Therefore, the outliers in the positional information obtained from the indoor positioning method based on RSS measurements occur often. For this reason, the performance of the positioning method can be degraded by the characteristics of the RF signal. To resolve this issue, a map-matching (MM) algorithm based on maximum probability (MP) estimation is applied to the indoor positioning method in this study. The MM algorithm locates the aberrant position of the user estimated by the positioning method within the limits of the adjacent pedestrian passages. Empirical experiments show that the positioning method can achieve higher positioning accuracy by leveraging the MM algorithm.

• 반도체디스플레이기술학회지
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• 제23권1호
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• pp.71-78
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• 2024

In indoor environments, since global positioning system (GPS) signals can be blocked by obstacles, such as building structure. the performance of GPS-based positioning methods can be degraded because of the loss of GPS signals. To solve this problem, various localization schemes using inertial measurement unit (IMU) sensors, such as gyroscope, accelerometer, and magnetometer, have been proposed to enhance the positioning accuracy in indoor environments. IMU-based positioning methods can estimate the location of the user by calculating the velocity and heading angle of the user without the help of GPS. However, low-cost MEMS IMUs may lead to drift error and large bias. In addition, positioning errors in IMU-based positioning approaches can be caused by the irrelevant motion of the pedestrian. In this study, we propose an enhanced indoor positioning method that provides more reliable localization results by using the camera, light detection and right (LiDAR), and ARKit framework on the iPhone. Through reliable positioning results and augmented reality (AR) experiences, our indoor positioning system can provide indoor space guidance services.

• Journal of Positioning, Navigation, and Timing
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• 제3권1호
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• pp.31-36
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• 2014

Precise Point Positioning (PPP) is a stand-alone precise positioning approach. As the quality of satellite orbit and clock products from analysis centers has been improved, PPP can provide more precise positioning accuracy and reliability. A combined use of Global Positioning System (GPS) and Global Orbiting Navigation Satellite System (GLONASS) in PPP is now available. In this paper, we explained about an approach for combined GPS and GLONASS PPP measurement processing, and validated the performance through the comparison with GPS-only PPP results. We also used the measurement obtained from the GRAS reference station for the performance validation. As a result, we found that the combined GPS/GLONASS PPP can yield a more precise positioning than the GPS-only PPP.

• 한국군사과학기술학회지
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• 제4권2호
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• pp.52-59
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• 2001

In this paper, we have proposed a capability of applying Global Positioning System(GPS) to cannon laying. High precision GPS positioning can be used for measuring precise positions and angles. Therefore, we have tested on applying GPS positioning technique to measurement of positions and angles, which related to cannon laying. First of all, we have determined a GPS reference position using various positioning methods. Then we have carried out several tests that are process of taking corner angles between neighboring two vectors. Each vector can be calculated by post/real time positioning of two GPS antennas placed on the both ends of the howitzer. The Comer Angles from Post processing(CAP) are compared with the other Corner Angles from Real time positioning(CAR). As the results, we have an agreement between CAP and CAR within 0.25 mil average, 0.29 mil standard deviation. Finally, we have discussed about the capabilities and problems in artillery arrangement using GPS.

• 한국정보통신학회논문지
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• 제27권1호
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• pp.139-142
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• 2023

In this paper, we propose a GNSS-UWB hybrid positioning system for indoor and outdoor seamless positioning. Fusion of GNSS and inertial sensors has been widely used as a method for estimating positions in places where GNSS reception sensitivity is low, and UWB technology, which started as a short-range wireless communication technology, is widely used indoors where GNSS is completely blocked. This paper proposes a method of mutual correction and fusion of the location information collected through GNSS and the location information collected from the UWB indoor positioning system when indoor and outdoor work occurs continuously and repeatedly, such as in an industrial site.

• 전자통신동향분석
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• 제38권3호
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• pp.11-19
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• 2023

Drones, which were early operated by remote control, have evolved to enable autonomous flight by combining various sensors and software tools. In particular, autonomous flight of drones was possible since the application of GNSS-RTK (global navigation satellite system with real-time kinematic positioning), a precision satellite navigation technology. For instance, unmanned drone delivery based on GNSS-RTK data was demonstrated for pizza delivery in Korea for the first time in 2021. However, the vulnerabilities of GNSS-RTK should be overcome for delivery drones to be commercialized. In particular, jamming in the navigation system and low positioning accuracy in urban areas should be addressed. Solving these two problems can lead to stable flight, takeoff, and landing of drones in urban areas, and the corresponding solutions are expected to establish a hybrid positioning technology. We discuss current trends in hybrid positioning technology that can either replace or complement GNSS-RTK for stable drone autonomous flight.

• 한국통신학회논문지
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• 제38C권1호
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• pp.131-140
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• 2013

기존의 전파에 의존한 실내 위치측위 시스템의 한계점 발생으로 실내환경에서 정확도 향상을 위한 새로운 방법의 도입이 필요한 시점이다. 최근 생태계 모방 기술이 미래의 핵심기술이 되었고, 이에 따라 귀소본능을 가진 동물들이 지구자기장을 탐색하여 생체자석으로 위치친지에 사용하는 점을 적용한 정확한 위치 측위 방법을 연구하였다. 실내 위치측위를 위한 새로운 자원인 지구자기장의 적용 가능성을 확인하기 위해 건물구조, 구성재료를 구분하고 실제 자기장센서를 탑재할 수 있는 구조물과 데이터수집 모듈을 설계한 뒤, Fingerprint 기법의 위치측위 시스템을 구성하여 위치측위 자원으로서의 지구자기장의 적용 가능성을 연구하였다. 위치측위 시스템 성능 평가에서 기존의 무선랜이 설치된 건물에서는 지구자기장 세기 기반의 위치측위 시스템이 무선랜 기반 위치측위 시스템과 유사하거나 약 20% 성능이 높이 나타났다. 이와같이 실내 위치측위를 위한 인프라 설치가 되어 있지 않는 환경에서는 지구자기장이라는 고유의 지구자원으로 실내 위치측위가 가능하다.

• 반도체디스플레이기술학회지
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• 제22권2호
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• pp.112-119
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• 2023

In urban environments, signals of Global Positioning System (GPS) can be blocked and reflected by tall buildings, large vehicles, and complex components of road network. Therefore, the performance of the positioning system using the GPS module in urban areas can be degraded due to the loss of GPS signals necessary for the position estimation. To deal with this issue, various localization schemes using inertial measurement unit (IMU) sensors, such as gyroscope and accelerometer, and Bayesian filters, such as Kalman filter (KF) and particle filter (PF), have been designed to enhance the performance of the GPS-based positioning system. Among Bayesian filters, the PF has been widely used for the target tracking and vehicle navigation, since it can provide superior performance in estimating the state of a dynamic system under nonlinear/non-Gaussian circumstance. This paper presents a positioning system that uses the double-stacked particle filter (DSPF) as well as the accelerometer, gyroscope, and GPS receiver on the smartphone to provide higher pedestrian positioning accuracy in urban environments. The DSPF employs a nonparametric technique (Parzen-window) to create the multimodal target distribution that approximates the posterior distribution. Experimental results show that the DSPF-based positioning system can provide the significant improvement of the pedestrian position estimation in urban environments.

• 정보통신설비학회논문지
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• 제9권3호
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• pp.92-101
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• 2010

Energy efficiency and safe mobility are the two key constituents of the future automobile. The technologies that enable these features are now heavily dependent upon information and communication technology rather than traditional auto-mechanical technology. This paper presents an exploratory project 'Smart&Green Vehicle Project' at Western Michigan University which is to improve the geographical location accuracy of vehicles and to study various applications of making such location data available. Global Positioning System (GPS), Inertial Navigation System (INS), Vehicular Ad-hoc Network (VANET) technology, and data fusion among these technologies are investigated. Testing and evaluation is done on systems which will gather vehicular positioning data during GPS signal loss. Vehicles in urban settings do not acquire accurate positioning data from GPS alone; therefore there is a need for exploration into technology that can assist GPS in urban settings. The goal of this project is to improve the accuracy of positioning data during a loss of GPS signal. Controlled experiments are performed to gather data which aided in assessing the feasibility of these technologies for use in vehicular platforms.