• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.30-35
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• 1990

Learning control of a robot manipulator is proposed using the backpropagation neural network. The learning controller is composed of both a linear feedback controller and a neural network-based feedforward controller. The stability analysis of the learning controller is presented. Three energy functions are selected in teaching the neural network controller : 1/2.SIGMA.vertical bar torque error vertical bar $^{2}$, 1/2.SIGMA..alpha. vertical bar position error vertical bar $^{2}$ + .betha. vertical bar velocity error vertical bar $^{2}$ + .gamma. vertical bar acceleration error vertical bar $^{2}$ and learning methods are presented. Simulation results show that the learning controller which is learned to minimize the third energy function performs better than the others in tracking problems. Some properties of the learning controller are discussed with simulation results.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.179-181
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• 2005

There is asymmetric in horizontal and vertical side of PDP cell. Every vertical line has BM(Black Mask) to improve luminance contrast. When error diffusion is processed in PDP system, these problems make an error bigger. In 4 inch PDP system, every red, green, blue color of test pattern is presented and each luminance is measured. That is called horizontal(H), diagonal right(R), diagonal left(L) and vertical(V). In red channel, high luminance descending order is V-H-R-L. In green channel, V-H-L-R. In blue channel, V-M-R=L. After average luminance of each direction is calculated. new weighted error diffusion(Weighted ED) is proposed. In digital image signal processing, the error in weighted ED is differ from ED's. The image of weighted ED is more less error compare to conventional ED and close to original image. As the gray level linearity and big size panel is adopted, weighted ED could produce good image.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2007.04a
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• pp.7-10
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• 2007

The 1st order vertical network of Korea was adjusted in 1987 at first time. This is the second adjustment of the 1st order vertical network of Korea by National Geographic Information Institute. All the levelling data were acquired by digital level with invar staff. The number of 1st order level lines are 36, and 34 level lines comprise 11 circles of level network. Backward and forward error of a few level lines are larger than the regulations of NGII, Korea. Also, 3 circles of vertical network has circuit closure error that is exceed the regulation. As the result of 1st order vertical network adjustment, the reference standard error of the vertical network was $1.8mm/{\surd}km$.

• Journal of Advanced Navigation Technology
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• v.26 no.4
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• pp.235-243
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• 2022

In this paper, in the case of an inertial navigation system, the posture estimation error in the initial alignment due to vertical deflection is analyzed. Posture estimation error due to DOV was theoretically analyzed based on the speed and posture error of INS. Simulations were performed to verify the theoretical grinding, and the results were in good agreement. For example, in the case of η=20", an alignment error of ϕ_N=0.00287°, ϕ_U=0.00196° occurred, and in the case of 𝜉=20", an error of ϕ_E= -0.00286° occurred. Through this, it was confirmed that the vertical posture error caused by the DOV occurred as a coupling characteristic of the INS posture error. It has been shown that an additional posture error may occur due to the DOV, which was not considered in the existing INS alignment, which means that correction for the DOV must be considered when applying high-precision INS.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.7-16
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• 1998

The Scanora/sup (R)/ X-ray unit uses the principles of narrow beam radiography and spiral tomography. Starting with a panoramic overview as a scout image. multiple tomographic projections could be selected. This study evaluated the accuracy of spiral tomography in comparison to routine panoramic radiography for dental implant treatment planning. An experimental study was performed on a cadaver mandible to assess the accuracy of panoramic radiography and spiral tomography film images for measurement of metallic spheres. After radiographic images of the metallic spheres on the surgical stent were measured and corrected for a fixed magnification of radiographic images. following results were obtained. 1. In the optimal position of the mandible. the minimal horizontal and vertical distortion was evident in the panoramic radiography images. The mean horizontal and vertical magnification error in anterior sites was 5.25％ and 0.75％. respectively. The mean horizontal and vertical magnification error in posterior sites was 0.50％ and 1.50％. respectively. 2. In the displaced forward or in an eccentric position of the mandible. the magnification error of the panoramic radiography images increased significantly over the optimal position. Overall, the mean horizontal magnification error of the anterior site in the different positions changed dramatically within a range of -17.25％ to 39.00％, compared to the posterior range of -5.25％ to 8.50％. However, the mean vertical magnification error stayed with the range of 0.5％ to 3.75％ for all the mandibular positions. 3. The magnification effects in the tomographic scans were nearly identical for the anterior and posterior with a range of 2.00％ to 5.75％ in the horizontal and 4.50％ to 5.50％ in the vertical dimension, respectively. 4. A statistically significant difference between the anterior and posterior measurements was found in the horizontal measurements of the panoramic radiography images of the displaced forward and backward position of the mandible(P<0.05). Also a significant difference between the optimal panoramic and tomographic projections was found only in the vertical measurement(P<0.05).

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.119-138
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• 1998

Recently measurements of atmospheric trace gases from satellite are vigorous. So the development of its data processing algorithm is important. In this study, retrievalof vertical ozone profile from the atmospheric transmittance measured by satellite solar occultation method and its sensitivity to temperature and pressure are investigated. The measured transmittance from satellite is assumed to be given by the limb path transmittance simulated using annual averaged Umkehr data for Seoul. The limb path transmittance between wavelengths $9.89{\mu}m$ and $10.2{\mu}m$ is simulated with respect to tangent heights using the ozone data of HALOE SIDS(Hallogen Occultation Experiment Simulated Instrument Data Set) as an initial profile. Other input data such as pressure and temperature are also from HALOE SIDS. Vertical ozone profile is correctly retrieved from the measured transmittance by onion-peeling method from 50km to 11km tangent heights with the vertical resolution of 3km. The bias error of $\pm0.001$ in measured transmittance, the forced error of $\pm3K$ in each layer temperature, and the forced $\pm3%$ error in each layer pressure are assumed for sensitivity tests. These errors are based on the ADEOS/ILAS error limitation. The error in ozone amount ranges from -6.5% to +6.9% due to transmittance error, from -9.5% to +10.5% due to temperature error, and from -5.1% to +5.4% due to pressure error, respectively. The present study suggests that accurate vertical ozone profile can be retrieved from satellite solar occultation method. Accuracy of vertical temperature profile is especially important in the retrieval of vertical ozone profile.

• Imaging Science in Dentistry
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• v.35 no.3
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• pp.115-119
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• 2005

Purpose : To evaluate the magnification error percentage in repeatedly taken panoramic radiographs of same patient and machine. Materials and Methods : 92 panoramic radiographs from 46 patients were traced and 30 horizontal and vertical measurements were made with digital sliding caliper. The results were compared with paired t-test. Results : There was no statistically significant difference between the two measurements. The overall difference as percentage error was $6.19\pm5.60\%$. The largest error as $14.61\pm12.44\%$ was found at condylar height 1, and smallest as $1.86\pm1.61\%$ at mandibular height. Overall vertical error excluding condylar height 1 was $3.76\pm3.97\%$, and the horizontal error $6.88\pm5.92\%$. Conclusion . Repeatedly taken panoramic radiographs of the same patient and machine was reliable since there was no significant percentage error difference but the percentage error ranged from $1.86\pm1.61\%\;to\;14.61\pm12.44\%$ indicating the error depends on the measuring site.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.11
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• pp.937-943
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• 2016

Vertical velocity is critical in many areas, such as the control of unmanned aerial vehicles, fall detection, and virtual reality. Conventionally, the integration of GPS (Global Positioning System) with an IMU (Inertial Measurement Unit) was popular for the estimation of vertical components. However, GPS cannot work well indoors and, more importantly, has low accuracy in the vertical direction. In order to overcome these issues, IMU-barometer integration has been suggested instead of IMU-GPS integration. This paper proposes a new complementary filter for the estimation of vertical velocity based on IMU-barometer integration. The proposed complementary filter is designed to minimize drift error in the estimated velocity by adding PID control in addition to a zero velocity update technique.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.8
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• pp.727-732
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• 2008

In this paper, the state-space representation of generalized complimentary filter is proposed. Complementary filter has the suitable structure to merge information from sensors whose frequency regions are complementary. First, the basic concept and structure of complementary filter is introduced. And then the structure of the generalized filter and its state-space representation are proposed. The state-space representation of complementary filter is able to design the complementary filter by applying modern filtering techniques like Kalman filter and $H_{\infty}$ filter. To show the usability of the proposed state-space representation, the design of Inertial Navigation System(INS) vertical channel damping loop using Global Positioning System(GPS) is described. The proposed GPS/INS damping loop lends the structure of Baro/INS(Barometer/INS) vertical channel damping loop that is an application of complementary filter. GPS altitude error has the non-stationary statistics although GPS offers navigation information which is insensitive to time and place. Therefore, $H_{\infty}$ filtering technique is selected for adding robustness to the loop. First, the state-space representation of GPS/INS damping loop is acquired. And next the weighted $H_{\infty}$ norm proposed in order to suitably consider characteristics of sensor errors is used for getting filter gains. Simulation results show that the proposed filter provides better performance than the conventional vertical channel loop design schemes even when error statistics are unknown.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.3
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• pp.15-22
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• 1999

In this study, a machining error estimation system far vertical lathes with structural deformation and geometric errors, is realized based on the virtual manufacturing technologies. The positional and directional errors of cutting tool are determined by considering the geometric errors and dimensions of machine components and by introducing the equilibrium condition between the cutting force and structural deformation. Especially, the machining errors of vertical lathes are estimated by using the prescribed cutting test(JIS B 6331). The system can be implemented to evaluate the machining accuracies of vertical lathes at the design process and to design the high precision vertical lathes.