• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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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.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.1
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• pp.1-14
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• 2018

The Global Positioning System (GPS) provides more accurate positioning estimation performance by processing L1 and L2 signals simultaneously through dual frequency signal processing technology at the L-band rather than using only L1 signal. However, if anti-spoofing (AS) mode is run at the GPS, the precision (P) code in L2 signal is encrypted to Y code (or P(Y) code). Thus, dual frequency signal processing can be done only when the effect of P(Y) code is eliminated through the L2 signal processing technology. To do this, a codeless technique or semi-codeless technique that can acquire phase measurement information of L2 signal without information about W code should be employed. In this regard, this paper implements L2 signal processing technology where two typical codeless techniques and four typical semi-codeless techniques of previous studies are applied and compares their performances to discuss the optimal technique selection according to implementation environments and constraints.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.65-72
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• 2002

In this study, actuator, sensor, guide, power transmission element and control method are considered for ultra-precision positioning apparatus. Through previous process, single plane X-Y stage with ultra-precision positioning is manufactured. Global stage for the purpose of materialization with robust system, is combined by using AC servo motor and ball screw and rolling guide. And ultra-precision positioning system is developed by micro stage with elastic hinge type and piezo element. global servo and micro servo for the purpose of materialization positioning accuracy with nm(nanometer) are controlled simultaneously by using incremental encoder and laser interferometer as displacement measurement sensor. Through previous process, ultra-precision positioning system(100mm stroke and $\pm$ l0nm positioning accuracy) with single plane X-Y stage are materialized.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.151-156
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• 2020

A technology for calculating the position of a device is very important for users who receive positioning services, regardless of various indoor/outdoor or with/without any positioning infrastructure existence environments. One of the positioning resources widely used at present, LTE, is a typical infrastructure that can overcome the space limitation, however its positioning method based on the position of the LTE base station has low accuracy. A method of constructing a radio wave map of an LTE signal has been proposed as a method for overcoming the accuracy, but it takes a lot of time and cost to perform high-density collection in a wide area. In this paper, we describe a method of creating a high-density DB for the entire region by using vehicle-based partial collection data. To create a positioning database, we applied the idea of Generative Adversarial Network (GAN), which has recently been in the spotlight in the field of deep learning, and learned the collected data. Then, a virtually generated map which having the smallest error from the actual data is selected as the optimum DB. We verified the effectiveness of the positioning DB generation algorithm using the positioning data obtained from un-collected area.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.47-48
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• 2022

The positioning technology that measures the position of a person or object is a key technology to deal with the location of the real coordinate system or converge the real and virtual worlds, such as digital twins, augmented reality, virtual reality, and autonomous driving. In estimating the location of a person or object at an indoor construction site, there are restrictions that it is impossible to receive location information from the outside, the communication infrastructure is insufficient, and it is difficult to install additional devices. Therefore, this study tested the direct sparse odometry algorithm, one of the visual Simultaneous Localization and Mapping (vSLAM) that estimate the current location and surrounding map using only image information, at an indoor construction site and analyzed its applicability as an indoor positioning technology. As a result, it was found that it is possible to properly estimate the surrounding map and the current location even in the indoor construction site, which has relatively few feature points. The results of this study can be used as reference data for researchers related to indoor positioning technology for construction sites in the future.

• Journal of the Korean Association of Geographic Information Studies
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• v.6 no.4
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• pp.51-58
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• 2003

Satellite-based positioning system such as global positioning system(GPS) has played a major role in data capture technology for constructing GIS database. Recent advances in satellite-based positioning technology have made the task of precisely locating features fast, easy, and inexpensive, and determined their current latitude and longitude. However, there are still situations where satellite-based positioning service will not provide users with desired precision such as in urban environments, that is, the only severe handicap still hampering satellite-based positioning is the well-known problem of restricted satellite visibilities. As the majority of the creation and updating of road and street network are carried out in urban environments, the obstruction problem considerably impedes the wider application of satellite-based positioning. This paper presents the current GPS-based positioning environment for GIS data acquisition in urban areas. A field experiment with measurement vehicle has been performed under varying operational conditions and areas where shading of satellite signal is encountered due to buildings and overpasses with measurement vehicle in order to evaluate the availability of existing GPS-based positioning. We found that the current GPS-base positioning system we used in this study was insufficient for a precise GIS data acquisition. This research would make a contribution for the development of base data to supplementary technology, which can complement the existing GPS-based positioning.

• Journal of Industrial Technology
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• v.28 no.A
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• pp.97-104
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• 2008

Recently, interests on positioning system for location-based services have been significantly increased. Many indoor environment systems using fingerprint scheme have been designed to take more accuracy of positioning, but they are inefficient in adapting to change of environments. In this paper, we focus on a client-based positioning system over WLAN for decreasing installation cost and adapting to change of environments. In the proposed system, APs with stable RSSI are selected as base APs independently for each reference point. Experimental results show that proposed system expands service area approximately 20% much than traditional systems using K-NN algorithm and needs only 20% modification process to fingerprint data compare with traditional systems whenever environment conditions are changed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.3
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• pp.255-260
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• 2009

This paper presents an experimental result of virtual mode input shaping for positioning stage. Input shaping is liable to increase the rise time of the system, which often degrades the performance of system. The virtual mode input, shaping is an input shaper design method to improve this problem. Experiments are performed with a precise positioning stage with a flexible beam of which natural frequency is adjustable. The experimental results show that the virtual-mode shaper is useful to reduce the rise time as well as the residual vibration of precise positioning stages.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.586-591
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• 2015

In recent years, along with the rapid development of LED technology, indoor positioning systems based on visible light communication (VLC) have been researched. In this paper, we propose an accurate indoor positioning method using white-light LEDs and a dual image sensor. Indoor LED lights are located at the ceiling in a room and broadcast information on their positions using VLC technology. A mobile device with a dual image sensor receives LED position information by VLC and estimates its position and azimuth angle. Simulation and experimental results are given to show the performance of the proposed indoor positioning system.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.564-573
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• 2015

GPS is the representative positioning technology for providing the location information. This technique has the disadvantage that does not operate in the shadow areas, such as urban or dense forest and the interior. This paper proposes a hybrid indoor positioning algorithm, which estimates a more accurate location of the terminal using strength of the Wi-Fi signal from the indoor AP. To determine the location of the user, we establish the most appropriate path loss model for the measurement environment. by using the RSSI value measured in a variety of environment such as building structure, person, distance, etc. The path loss exponent obtained by the path loss model is changed according to the environment. REKF, PF estimate the position of the terminal by using measured value from the AP with path loss exponent. For more accurate position estimation, we select positioning system by the value of threshold measured by experiments rather than a single positioning system. Experimental results using the proposed hybrid algorithm show that the performance is improved by about 17% than the conventional single positioning method.