• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4B
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• pp.647-658
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• 2010

Many localization schemes estimate the locations of radio nodes based on the physical locations of anchors and the connectivity from the anchors. Since they only consider the knowledge of the anchors without else other nodes, they are likely to have enormous error in location estimate unless the range information from the anchors is accurate or there are sufficiently many anchors. In this paper, we propose a novel localization algorithm with the location knowledge of anchors and even one-hop neighbors to localize unknown nodes in the uniform distance from all the one-hop neighbors without the range information. The node in the uniform distance to its all neighbors reduces the location error relative to the neighbors. It further alleviates the location error between its actual and estimated locations. We evaluate our algorithm through extensive simulations under a variety of node densities and anchor placement methods.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.4
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• pp.209-216
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• 1996

In this paper, we propose a learning method of multi-layer perceptrons (MLPs) with 8-bit data precision. The suggested method uses the cross-entropy cost function to remove the slope term of error signal in output layer. To decrease the possibility of overflows, we use 16-bit weighted sum results into the 8-bit data with appropriate range. In the forwared propagation, the range for bit-conversion is determined using the saturation property of sigmoid function. In the backwared propagation, the range for bit-conversion is derived using the probability density function of back-propagated signal. In a simulation study to classify hadwritten digits in the CEDAR database, our method shows similar generalization performance to the error back-propagation learning with 16-bit precision.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.69-71
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• 2008

We have developed a current range extension method to obtain the ratio error and phase displacement of a current transformer (CT) by using absolute evaluation method and two different CTs. The method was applied to CTs under test with the current ratios of the range of 5,000 A / 1 A - 20,000 A / 1 A. The ratio error and phase displacement of the CT under test obtained in this study are consistent with those measured at the national institute in Germany using the same CT under test within an expanded uncertainty (k = 2) in the overall current ratios.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.9
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• pp.785-798
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• 2004

This paper introduces the development of a range sensor based integrated navigation system for a multi-functional indoor service robot, called PSR (Public Service Robot System). The proposed navigation system includes hardware integration for sensors and actuators, the development of crucial navigation algorithms like mapping, localization, and path planning, and planning scheme such as error/fault handling. Major advantages of the proposed system are as follows: 1) A range sensor based generalized navigation system. 2) No need for the modification of environments. 3) Intelligent navigation-related components. 4) Framework supporting the selection of multiple behaviors and error/fault handling schemes. Experimental results are presented in order to show the feasibility of the proposed navigation system. The result of this research has been successfully applied to our three service robots in a variety of task domains including a delivery, a patrol, a guide, and a floor cleaning task.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.5-12
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• 2010

The purpose of this study is to present the EV range in HDRI acquisition process to create luminance map. The proposed method in this study is to capture the scene at EV ${\pm}0$ that is the longest exposure points and reference point in the scene. With this reference point, sets of 25 LDRI test case were taken manually at ${\pm}2$ EV using the aperture-priority manual mode. The 25 HDRIs were created using Adobe Photoshop. The HDRIs were then imported Radiance lighting simulation program to be analyzed into falsecolor. The analysis results of the 25 HDRIs test case are 50[%] of the all tested case have a margin of error of 10[%]. In case of f/5.6, the luminance map generated with HDRI were similar to the spot luminance meter. As a result, the EV range to reduce error of luminance map generated with HDRI is EV $+2{\sim}{\pm}0{\sim}-10$.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.41-47
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• 2019

A BIS(Bus Information System) collects, processes and analyzes information such as real-time location and operation status during bus operation. And It is a system that provides valid information to citizens, drivers, traffic centers and bus companies. Transport information system sent by an each bus is collected through GPS(Global Positioning System), DSRC(Dedicated Short Range Communications), Beacon and passed to transport information center. BIS data by collected is handled and analyzed. Next, it is transmitted to citizen, drivers and bus companies in real time. The result of 5 times simulation satisfied the test criteria(error range ${\pm}10m$) with an average error range of 3.306m, and the reliability is increased. In this paper, we propose a improved location transfer component that can provide users to quicker and more accurate location information than existing BIS using GPS of smart phone. It can be seen that reliability is improved by securing improved bus position data.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.3
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• pp.355-363
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• 2024

This study proposes a method for determining the optimal target size for an artillery range considering ballistics and environmental conditions. To this end, the size of the probable error of each type of ammunition and charge determined during shooting were considered, and the effect of the firing position and target terrain characteristics on the target size was analyzed. In conclusion, the size of the target increased as the range increased, and a larger target size was required for the DPICM than for the general high explosive. Accordingly, the optimal target size must be determined by considering various factors such as topographical characteristics, shooting position location, and shooting range safety standards.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3700-3708
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• 2023

The stochastic origin ensembles method with resolution recovery (SOE-RR) has been proposed to reconstruct proton-induced prompt gammas (PGs), and the reconstructed PG image was used for range verification. However, due to low detection efficiency, the number of valid events is low. Such a low-count condition can degrade the accuracy of the SOE-RR method for proton range verification. In this study, we proposed two strategies to improve the reconstruction of the SOE-RR algorithm for low-count PG imaging. We also studied the number of iterations and repetitions required to achieve reliable range verification. We simulated a proton beam (10⁸ protons) irradiated on a water phantom and used a two-layer Compton camera to detect 4.44-MeV PGs. Our simulated results show that combining the SOE-RR algorithm with restricted volume (SOE-RR-RV) can reduce the error of the estimation of the Bragg peak position from 5.0 mm to 2.5 mm. We also found that the SOE-RR-RV algorithm initialized using a back-projection image could improve the convergence rate while maintaining accurate range verification. Finally, we observed that the improved SOE-RR algorithm set for 60,000 iterations and 25 repetitions could provide reliable PG images. Based on the proposed reconstruction strategies, the SOE-RR algorithm has the potential to achieve a positioning error of 2.5 mm for low-count PG imaging.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1051-1054
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• 2003

For micro-weighing, null balance method is widely used in the precision industrial fields, such as biomedicine, semiconductor, chemistry and so on. In order to obtain high resolution and large measurement range simultaneously, the mechanism should be analyzed and optimized. However, large measurement error can be generated according to the mass loading position and this error is called as a corner loading error. The corner loading error is caused by the parallelism error of a Roberval mechanism used to minimize it. The corner loading error is one of the most dominant error sources that should be removed. It is possible to design that the mechanism has no corner loading error theoretically, but the mechanism of the micro weighing device is very difficult to be realized as original design due to assembling and manufacturing error. For the required specification of the device, the precise manufacturing technique under a few $\mu\textrm{m}$ is required for the realization of the design. In this paper, the effects of the parallelism error are analyzed by using Lagrange method and verified by experiment. Also, the compensation mechanism is proposed and the corner loading error is reduced by restoring tile parallelism.

• Journal of Convergence for Information Technology
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• v.10 no.5
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• pp.30-35
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• 2020

In this paper, we analyzed the tracking error for the monopulse radar by controlling the phase difference, amplitude ratio and engagement angle of the cross-eye jammer. Cross-eye jamming is an important jamming method for monopulse radars, which causes a displacement in the radar receiving antenna input and misleads the radar's tracking angle. As a result of analyzing the tracking distance error of the radar while changing the engagement angle between the monopulse radar and jammer, the maximum distance error occurs when the engagement angle is 0° and the phase difference is 180°. It was confirmed that the error decreased to 70% or less of the maximum distance error into 45°~135°. In order to increase the efficiency of jammers, it is necessary to study rotary jammers or multi-channel jammers. This study will be very useful for the design of cross-eye jammers for aircraft and ships.