• Journal of Positioning, Navigation, and Timing
• /
• v.8 no.4
• /
• pp.183-192
• /
• 2019

In fingerprint-based wireless positioning, it is necessary to establish a DB of the unmeasured area. To this end, a method of estimating the position of a base station based on a signal propagation model, and a method of estimating the information of the received signal in the unmeasured area based on the estimated position of the base station have been investigating. The purpose of this paper is to estimate the position of the base station using the measured information and to analyze the performance of the positioning. Vehicles equipped with a GPS receiver and signal measuring equipment travel the service area and acquire location-based Reference Signal Received Power (RSRP) measurements. We propose a method of estimating the position of the base station using the measured information. And the performance of the proposed method is analyzed on a simulation basis. The simulation results confirm that the accuracy of the positioning is affected by the measured area and the Dilution of Precision (DOP), the accuracy of the position information obtained by the GPS receiver, and the errors of the signal included in the RSRP. Based on the results of this paper, we can expect that the position of the base station can be estimated and the DB of the unmeasured area can be constructed based on the estimated position of the base stations and the signal propagation model.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.04a
• /
• pp.445-448
• /
• 2004

Linear motor is very rapidly substituted for rotary motor and ball screw for precision positioning applications because of its characteristics such as high speed, no backlash and simplicities. A precision positioning system which is composed of linear motion(LM) guide and linear motor is widely used since it has easy controllable property but this system has low accuracy problem caused by friction of the LM guide. In this study, a scanning type XY stage is manufactured and some experiments is performed to improve the accuracy of the stage.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.10a
• /
• pp.36-40
• /
• 2003

In order to discuss the availability of aerostatic guideways driven by the coreless linear motor to ultra precision machine tools, a prototype of guideway is designed and tested in this research. A coreless linear DC motor with the continuous force of 156N and a laser scale with the resolution of $0.01\mu\textrm{m}$ are used as the feeding system. The experiments are performed on the static stiffness, motion accuracy, positioning accuracy, microstep response and variation of velocity. The guideway also has $0.21\mu\textrm{m}$ of positioning error and $0.09\mu\textrm{m}$ of repeatability, and it shows the stable response against the $0.01\mu\textrm{m}$ resolution step command. The velocity variation of feeding system is less than 0.6%. From these results, it is confirmed that the aerostatic guideway driven by the coreless linear motion is very useful for the ultra precision machine tools.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.3
• /
• pp.746-750
• /
• 2016

Dilution of Precision (DOP), as a measure of positioning accuracy, is an essential factor. Therefore, the DOP relationship between systems is very important. In this paper, the DOP relationship between TDOA and TOA in systems lacking clock bias is derived analytically and verified experimentally. Also, using those of earlier studies, the DOP relationship in each of defined systems is derived analytically.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.4
• /
• pp.26-31
• /
• 2008

본 논문은 정밀 위치결정 시스템의 잔류진동을 효과적으로 제거할 수 있는 입력성형기법을 소개하고, 실시간 입력성형기법을 적용하는 방법을 설명하였다. 또한 두 가지 응용 분야에 대한 실험결과를 바탕으로 입력성형기법의 성능을 고찰하였다. 일반적으로 입력성형기법은 정밀 위치결정 시스템에 대해 동작 완료시간을 단축시키는 효과가 있을 뿐만 아니라 위치결정 정밀도를 향상시키는 효과가 있다. 그리고 되먹임제어 방법에 비해 적용방법도 간단하며 저렴하게 구성할 수 있다는 장점이 있으므로 많은 정밀 위치결정 시스템에 유용할 것으로 생각된다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.10
• /
• pp.20-28
• /
• 2011

This paper proposes a reliable high-precision positioning system that converges a satellite navigation system and a vision system in order to resolve position errors and outdoor shaded areas, two disadvantages of a satellite navigation system. In kinematic point positioning, the number of available satellite navigation systems changes in accordance with a moving object's position. For location determination of the object, it should receive location data from at least four satellite navigation systems. However, in urban areas, exact location determination is difficult due to factors like high buildings, obstacles, and reflected waves. In order to deal with the above problem, a vision system was employed. First, determine an exact position value of a specific building in urban areas whose environment is poor for a satellite navigation. Then, identify such building by a vision system and its position error is corrected using such building. A moving object can identify such specific building using a vision system while moving, make location data values, and revise location calculations, thereby resulting in reliable high precision location determination.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.48 no.3
• /
• pp.235-241
• /
• 2012

The efficiency tests of automatic positioning transmitter (APT) using satellite on life jacket were carried out to minimize casualties of fishermen and to make system optimization for effective SAR (Search and Rescue) operation. As the result of the tests, average position was equaled on the comparison between SPOT using low earth orbit satellite and DGPS (Differential Global Positining System), but standard deviation of DGPS for latitude and longitude were 66.4% and 46.3% smaller than those of SPOT. The position precision of SPOT was almost two times lower than LGT using geostationary satellite to compare 95% circular error probability. However, the success rate of receiver for SPOT was revealed as 86.5~94.1% on the experiments in the South Sea and the West Sea and it was 4.5 times higher than LGT. Therefore, SPOT is expected to contribute greatly to the rapid rescue of victim.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.3
• /
• pp.285-292
• /
• 2020

This paper introduces a new computational efficient Dilution of Precision (DOP)-based landmark exclusion method while ensuring the safety of the LiDAR-based navigation system that uses an innovation-based Nearest-Neighbor (NN) Data Association (DA) process. The NN DA process finds a correct landmark association hypothesis among all potential landmark permutations using Kalman filter innovation vectors. This makes the computational load increases exponentially as the number of landmarks increases. In this paper, we thus exclude landmarks by introducing DOP that quantifies the geometric distribution of landmarks as a way to minimize the loss of integrity performance that can occur by reducing landmarks. The number of landmarks to be excluded is set as the maximum number that can satisfy the integrity risk requirement. For the verification of the method, we developed a simulator that can analyze integrity risk according to the landmark number and its geometric distribution. Based on the simulation, we analyzed the relationship between DOP and integrity risk of the DA process by excluding each landmark. The results showed a tendency to minimize the loss of integrity performance when excluding landmarks with poor DOP. The developed method opens the possibility of assuring the safety risk of the Lidar-based navigation system in real-time applications by reducing a substantial amount of computational load.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.6 no.4
• /
• pp.51-58
• /
• 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 the Korean Society for Precision Engineering
• /
• v.14 no.1
• /
• pp.29-51
• /
• 1997

The purpose of the survey is to identify possible new areas of research relating to nanotechnology and in particular areas in which the established facilities of the Centre for Metrology can be employed to good effect. This survey indicates that nanotechnology, a sub set of the more embracing Nano Science, is a rapidly developing discipline with good potential for Electronic and Mechanical Engineering. Nanotechnology includes three areas: Nanometrology, Nanometer positioning and Control, and Nanomanufacturing. In each of the areas, the current research situation and developing trends have been summarised. Possibilities for future work indicated.