• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.302-313
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• 2018

As the demand for indoor location recognition system has been rapidly increased in accordance with the increasing use of smart devices and the increasing use of augmented reality, indoor positioning systems(IPS) using BLE (Bluetooth Lower Energy) beacons and UWB (Ultra Wide Band) have been developed. In this paper, a positioning plate is generated by using trilateration technique based on BLE Beacon and using RSSI (Received Signal Strength Indicator). The resultant value is used to calculate the PDR-based coordinates using the positioning element of the Inertial Measurement Unit sensor, We propose a precise indoor positioning algorithm that combines RSSI and PDR technique. Based on the plate algorithm proposed in this paper, the experiment have done at large scale indoor sports arena and airport, and the results were successfully verified by 65% accuracy improvement with average 2.2m error.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10A
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• pp.727-735
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• 2009

To alleviate positioning error using wireless ultra-wideband (UWB) is primary concern, and it has been studied how to reduce the positioning error effectively. Thanks to many repeated transmissions of UWB signals, we can have a variety of selections to point out the most precise positioning result. Towards this, scanning method has been preferred to be used due to its simplicity. This exhaustive method firstly fixes the candidate position, and calculates the sum of distances from observed positions. However, it has tremendous number of computations, and the complexity is more serious if the size of two-dimensional range is the larger. To mitigate the large number of computations, this paper proposes the technique employing genetic algorithm and block windowing. To exploit its superiority, simulations will be conducted to show the reduction of complexity, and the efficiency on positioning capability.

• Journal of Astronomy and Space Sciences
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• v.18 no.2
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• pp.129-136
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• 2001

The accuracy of GPS applications is heavily dependent on the satellite ephemeris and earth orientation parameter. Specially applications like as the real time monitoring of troposphere and ionosphere require real time or predicted ephemeris arid earth orientation parameter with very high quality. IGS is producing IGS ultra rapid product called IGU for real time applications which includes the information of ephemeris and earth orientation. IGU is being made available twice everyday at 3:00 and 15:00 UTC arid covers 48 hours. The first 24 hours of it are based on actual GPS observations and the second 24 hours extrapolated. We will construct the processing strategy for yielding ultra rapid product and demonstrate the propriety through producing it using 48 hours data of 32 stations.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.149-157
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• 2009

The orbit ephemeris of Global Positioning System(GPS) is one element to determine the surveying accuracy and there are broadcasting ephemeris and precise ephemeris, IGS rapid orbit and IGS ultra rapid orbit in the orbit ephemeris of GPS. In this study, test area was selected in Uljin, Kyungsanbukdo and GPS surveying was accomplished at 37 points in the test area. Then baseline solution was done on 74 baseline using broadcasting ephemeris and precise ephemeris and analysis by TGO and the results were compared. Comparison results were showed that there were nearly no difference between the two results but in case of relative precision of the baseline, it was slightly better the baseline results of precise ephemeris which showed 0.706ppm than the baseline results of broadcasting ephemeris which showed 0.708ppm.

• Hip & pelvis
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• v.36 no.1
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• pp.26-36
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• 2024

Total hip arthroplasty (THA) is a frequently performed procedure; the objective is restoration of native hip biomechanics and achieving functional range of motion (ROM) through precise positioning of the prosthetic components. Advanced three-dimensional (3D) imaging and computed tomography (CT)-based navigation are valuable tools in both the preoperative planning and intraoperative execution. The aim of this study is to provide a thorough overview on the applications of CT scans in both the preoperative and intraoperative settings of primary THA. Preoperative planning using CT-based 3D imaging enables greater accuracy in prediction of implant sizes, leading to enhancement of surgical workflow with optimization of implant inventory. Surgeons can perform a more thorough assessment of posterior and anterior acetabular wall coverage, acetabular osteophytes, anatomical landmarks, and thus achieve more functional implant positioning. Intraoperative CT-based navigation can facilitate precise execution of the preoperative plan, to attain optimal positioning of the prosthetic components to avoid impingement. Medial reaming can be minimized preserving native bone stock, which can enable restoration of femoral, acetabular, and combined offsets. In addition, it is associated with greater accuracy in leg length adjustment, a critical factor in patients' postoperative satisfaction. Despite the higher costs and radiation exposure, which currently limits its widespread adoption, it offers many benefits, and the increasing interest in robotic surgery has facilitated its integration into routine practice. Conducting additional research on ultra-low-dose CT scans and examining the potential for translation of 3D imaging into improved clinical outcomes will be necessary to warrant its expanded application.

• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.199-206
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• 2015

For real-time precise positioning, IGS provides ephemeris predictions (IGS ultra-rapid, IGU) and real-time ephemeris estimates (real-time service, RTS). Due to the RTS data latency, which ranges from 5 s to 30 s, a short-term prediction process is necessary before applying the RTS corrections. In this paper, the real-time performance of the RTS correction and IGU prediction are compared. The RTS correction availability for the GPS satellites observed in Korea is computed as 99.3%. The RTS correction is applied to broadcast ephemeris to verify the accuracy of the RTS correction. The 3D orbit RMS error of the RTS correction is 0.043 m. Prediction of the RTS correction is modeled as a polynomial, and then the predicted value is compared with the IGU prediction value. The RTS orbit prediction accuracy is nearly equivalent to the IGU prediction, but RTS clock prediction performance is 0.13 m better than the IGU prediction.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.953-961
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• 2011

IGS (International GNSS Service) predicted orbits contained in IGS ultra-rapid orbits is suitable for real-time or near-real-time precise positioning. In this paper, we analyzed orbit anomalies of the IGS predicted orbits and detected the anomalies NANU (Current Notice Advisories to NAVSTAR Users) messages and IGS BRDC (Broadcast Ephemerides). As a results, the orbit anomalies of the predicted orbits were observed 93 times in 2010. In case of using the NANUs, we could get detection performance of 88% about the IGS predicted orbits's anomalies. And we could achieve 95% detection performance when the NANUs and BRDCs were used together.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.1
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• pp.53-58
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• 2017

A fine stage is developed for the 3-DOF error compensation of a linear axis in order to improve the positioning accuracy. This stage is designed as a planar parallel mechanism, and the joints are based on a flexure hinge to achieve ultra-precise positioning. Also, the effect of Abbe's offsets between the measuring and driving coordinate systems is minimized to ensure an exact error compensation. The mode shapes of the designed stage are analyzed to verify the desired 3-DOF motions, and the workspace and displacement of a piezoelectric actuator (PZT) for compensation are analyzed using forward and inverse kinematics. The 3-DOF error of a linear axis is measured and compensated by using the developed fine stage. A marked improvement is observed compared to the results obtained without error compensation. The peak-to-valley (PV) values of the positional and rotational errors are reduced by 92.6% and 91.3%, respectively.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.61-72
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• 2010

This paper addresses the problem of moving object localization using Ultra-Wide-Band(UWB) range measurement and the method of location accuracy improvement of the indoor moving object. Unlike outdoor environment, it is difficult to track moving object position due to various noises in indoor. UWB is a radio technology that has attention for localization applications recently. UWB's ranging technique offer the cm accuracy. Its capabilities for data transmission, range accurate estimation and material penetration are suitable technology for indoor positioning application. This paper propose a positioning algorithm of an moving object using UWB ranging technique and particle filter. Existing positioning algorithms eliminate estimation errors and bias after location estimation of mobile object. But in this paper, the proposed algorithm is that eliminate predictable UWB range distance error first and then estimate the moving object's position. This paper shows that the proposed positioning algorithm is more accurate than existing location algorithms through experiments. In this study, the position of moving object is estimated after the triangulation and eliminating the bias and the ranging error from estimation range between three fixed known anchors and a mobile object using UWB. Finally, a particle filter is used to improve on accuracy of mobile object positioning. The results of experiment show that the proposed localization scheme is more precise under the indoor.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.4
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• pp.747-754
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• 2013

This study introduces a recently designed desktop-sized NC turning system and its components. This machine is designed for the ultra-precise turning of parts with a diameter of 0.5-20 mm with minimum space usage for the machine. This study aims to achieve submicron-level accuracy of movements and good rigidity of the machine for precision machining using the desktop-sized machine. The components such as the main machine structure, air bearing servo spindle, and XZ stage with needle roller guides are designed, and the designed machine is built with a PC-based CNC controller. Its static and dynamic stiffness performances and positioning resolutions are tested. Through machining tests with single-crystal diamond tools, a form error less than $0.8{\mu}m$ and surface roughness (Ra) of $0.03{\mu}m$ for workpieces are obtained.