• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.246-251
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• 2012

This paper proposes a new position compensation method for misaligned Hall-effect sensors of BLDCM(Brushless DC Motor). If the Hall-effect sensors are installed at wrong position, the exact rotor position cannot be obtained. Therefore, when the BLDCM is controlled with this wrong position, the torque ripple can be increased and the average torque also decreases. The back-EMF of BLDCM can be obtained by using the voltage equation and by multiplying the back-EMF constant and rotor speed. At a constant speed, the estimated back-EMF by using the multiplication of the back-EMF constant and rotor speed is constant, but the estimated back-EMF from the voltage equation decreases at the commutation point because the line-to-line back-EMF of two conducting phases is start to decrease at this point. Therefore, by using the difference between these two estimated back-EMFs, the commutation point of the phase current can be determined and position compensation can be carried out. The proposed position correction method doesn't require additional hardware circuit and can be easily implemented. The validity of the proposed position compensation method is verified through several experiments.

• Journal of Aerospace System Engineering
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• v.5 no.2
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• pp.1-7
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• 2011

On this study, applicable aircraft pitot-static system airworthiness requirements and flight test techniques for PEC(Position Error Correction) to KAS Part 23 airworthiness standards are introduced. Also, pros and cons, applicable test conditions, test procedures and required test parameters of each flight test techniques are reviewed on this study.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.13-15
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• 2006

This paper describes the problem generated in PLS luminous flux measurement with integrating sphere. In RS case, we don't use the center position of the sphere but side position for flux test The difference of the lamp position makes the luminous flux difference of same light source. We confirmed the phenomenon with three other kinds of lamps and ensured the repeatability and reliability of this work at two laboratories. finally, the correction factor which should be applied for the PLS test at Side position was calculated.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.433-439
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• 2016

Several low-cost global navigation satellite system (GNSS) receivers do not support general range-domain correction, and DGNSS-CP (differential GNSS) method had been suggested to solve this problem. It improves its position accuracy by projecting range-domain corrections to the position-domain and then differentiating the stand-alone position by the projected correction. To project the range-domain correction, line-of-sight vectors from the receiver to each satellite should be calculated. The line-of-sight vectors can be obtained from GNSS broadcast ephemeris data or satellite direction information, and this paper shows positioning performance for the two methods. Stand-alone positioning result provided from Septentrio PolaRx4 Pro receiver was used to show the difference. The satellite direction information can reduce the computing load for the DGNSS-CP by 1/15, even though its root mean square(RMS) of position error is bigger than that of ephemeris data by 0.1m.

• Journal of Auto-vehicle Safety Association
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• v.14 no.2
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• pp.39-44
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• 2022

This paper presents LiDAR static obstacle map based vehicle position correction algorithm for urban autonomous driving. Real Time Kinematic (RTK) GPS is commonly used in highway automated vehicle systems. For urban automated vehicle systems, RTK GPS have some trouble in shaded area. Therefore, this paper represents a method to estimate the position of the host vehicle using AVM camera, front camera, LiDAR and low-cost GPS based on Extended Kalman Filter (EKF). Static obstacle map (STOM) is constructed only with static object based on Bayesian rule. To run the algorithm, HD map and Static obstacle reference map (STORM) must be prepared in advance. STORM is constructed by accumulating and voxelizing the static obstacle map (STOM). The algorithm consists of three main process. The first process is to acquire sensor data from low-cost GPS, AVM camera, front camera, and LiDAR. Second, low-cost GPS data is used to define initial point. Third, AVM camera, front camera, LiDAR point cloud matching to HD map and STORM is conducted using Normal Distribution Transformation (NDT) method. Third, position of the host vehicle position is corrected based on the Extended Kalman Filter (EKF).The proposed algorithm is implemented in the Linux Robot Operating System (ROS) environment and showed better performance than only lane-detection algorithm. It is expected to be more robust and accurate than raw lidar point cloud matching algorithm in autonomous driving.

• Journal of Korean Foot and Ankle Society
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• v.14 no.1
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• pp.21-24
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• 2010

Purpose: The incomplete reduction of the sesamoid has lately been issued as cause for recurrence. In this study, we analysed factors that may influence reduction of sesamoid. Materials and Methods: The study consists of 50 cases operated by single surgeon. Eighteen cases were done by proximal chevron osteotomy, and 32 cases were done by scarf osteotomy. Hallux valgus (HV) angle and intermetatarsal (IM) angle were measured before and three months after the surgery. Sesamoid position (SP) was classified according to Hardy and Clapham grade system. Results: After the proximal chevron osteotomy, the correction of the mean HV angle was $19.5^{\circ}$, and IM angle was $6.2^{\circ}$. SP was changed from 5.6 to 3.4 grade. After the Scarf osteotomy, the correction of the mean HV angle was 25 degree, and IM angle was $9^{\circ}$. SP was changed from 5.5 to 2.8 grade. There was difference of sesamoid's correction between two different method of surgery (p=0.127). However, better correction of sesamoid was witnessed with bigger correction angle regardless of method of surgery (p=0.002, 0.001). Conclusion: We believe surgical method do not effect sesamoid's correction but more correction angle can result in better correction of sesamoid position.

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.99-105
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• 2011

This research presents the correction method to correct the location error of cloud caused by parallax error, and how the method can reduce the position error. The procedure has two steps: first step is to retrieve the corrected satellite zenith angle from the original satellite zenith angle. Second step is to adjust the location of the cloud with azimuth angle and the corrected satellite zenith angle retrieved from the first step. The position error due to parallax error can be as large as 60km in case of 70 degree of satellite zenith angle and 15 km of cloud height. The validation results by MODIS(Moderate-Resolution Imaging Spectrometer) show that the correction method in this study properly adjusts the original cloud position error and can increase the utilization of geostationary satellite data.

• Journal of the Korea Fashion and Costume Design Association
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• v.17 no.3
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• pp.61-71
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• 2015

In this study, visual evaluation was performed with changes in peplums design to provide data which can enhance wearing image effects at the production of peplums one-piece. According to changes in volume and position of peplums, a total of 9 stimulants were chosen. Then, they were evaluated using a seven-point rating scale against 50 fashion students. The data has been analyzed by Factor Analysis, ANOVA, $Scheff{\acute{e}}$'s Test and the MCA method. The results of the study are as follows : 1. According to factor analysis, the components of visual evaluation depending on the changes in volume and position variations of peplums were divided into four factors: elegance, individuality, upper body correction and upper body emphasis. 2. According to visual evaluation depending on changes in the position variations of peplum, 'high waist' and 'natural waist' revealed a significant difference in elegance, individuality and upper body correction. 'Low waist' was observed in all four positions. 3. According to visual evaluation depending on the changes in volume of peplums, a significant difference at $45^{\circ}$ was observed in except for elegance. Significant differences at $90^{\circ}$ and $180^{\circ}$ were observed in all four positions. 4. In terms of interactions over in volume and position variations of peplums, interaction effects were found in two factors.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.3
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• pp.34-41
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• 1996

This work deals with finding a suitable position correction algorithm of industrial robot based on measuring particular points, which calculates two dimensional correction quantities and the must allow visually acceptable door-chassis assembly task. Three optimizing algorithms corresponding to three differ- ent error based performance indices are compared and selected to the best one, in terms of the predefined total uniformity, line uniformity and computational time. The selected algorithm(Total Error Minimization) is implemented for a simple door-chassis model to show its effectiveness.

• Journal of Veterinary Clinics
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• v.39 no.1
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• pp.28-31
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• 2022

A 5-week old Thoroughbred foal was presented with severe left carpal valgus. Radiographs of the dorsopalmar projections confirmed the deviation was 14 degrees. Surgery using a single-position screw traversing the physis of the distal radius was performed. The limb was almost straight (2 degrees) 3 weeks after surgery. Visual/radiograph follow-up 7 months after screw removal revealed no over-correction after removal of the screw. Transphyseal bridging using a single-position screw without lateral periosteal transection of distal radius was successful for the correction of foals with this condition.