• Journal of IKEEE
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• v.20 no.1
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• pp.1-8
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• 2016

In this paper, we propose an effective time-of-arrival (TOA)-based localization method with adaptive bias computation in indoor environments. The goal of the localization is to estimate an accurate target's location in wireless localization system. However, in indoor environments, non-line-of-sight (NLOS) errors block the signal propagation between target device and base station. The NLOS errors have significant effects on ranging between two devices for wireless localization. In TOA-based localization, finding the target's location inside the overlapped area in the TOA-circles is difficult. We present an effective localization method using compensated distance with adaptive bias computation. The proposed method is possible for the target's location to estimate an accurate location in the overlapped area using the measured distances with subtracted adaptive bias. Through localization experiments in indoor environments, estimation error is reduced comparing to the conventional localization methods.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.56-61
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• 2006

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, wheelset manufacturing for test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 110km/h for estimating the running safety of Incheon Int'l Airport EMU. As the test results, could confirm the curving performance and running safety of Incheon Int'l Airport EMU from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.8, and lateral force allowance limit and wheel load reduction ratio were enough safe.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.4
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• pp.161-167
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• 2001

Camera calibration is very important problem in 3D measurement using vision system. In this paper is proposed the simple method for camera calibration. It is designed that uses the principle of vanishing points and the concept of corresponding points extracted from the parallel line pairs. Conventional methods are necessary for 4 reference points in one frame. But we proposed has need for only 2 reference points to estimate vanishing points. It has to calculate camera parameters, focal length, camera attitude and position. Our experiment shows the validity and the usability from the result that absolute error of attitude and position is in $10^{-2}$.

• ETRI Journal
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• v.43 no.6
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• pp.978-990
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• 2021

This article presents techniques for improved estimation of symbol timing offset (STO) and carrier frequency offset (CFO) for dual-polarization (DP) orthogonal frequency division multiplex (DP-OFDM) systems. Recently, quaternion multiple-input multiple-output OFDM has been proposed for high spectral efficiency communication systems, which can flexibly explore different types of diversities such as space, time, frequency, and polarization. This article focuses on synchronization techniques for DP-OFDM systems using a cyclic prefix, where the application of quaternion algebra leads to new improved estimators. Simulations performed for DP system methods show faster reduction of STO estimator variance with a double-slope line in the logvariance line versus signal-to-noise ratio (SNR) plot compared with singlepolarization (SP) counterparts, and simulations for CFO estimates show a 3-dB gain of DP over SP estimates for same SNR values defined, respectively, for quaternion-valued or complex-valued signals. Cramer-Rao bounds for STO and CFO are derived for the synchronization methods, correlating with the observed gains of DP over SP OFDM systems.

• Korean Journal of Breeding Science
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• v.43 no.1
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• pp.23-31
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• 2011

To investigate dose-effect of a chemical mutagen, sodium azide on a rice elite line, Suweon472, seed aliquots were treated with five different concentrations of sodium azide. The degree of mutation levels of each aizde concentration were estimated by using DNA fingerprinting techniques such as RAPD and AFLP. Some selected mutant lines ($M_4$) were also subjected for DNA fingerprinting to estimate their mutation levels by comparing the banding patterns of the wild type, Suweon 472. RAPD and AFLP fingerprinting patterns indicated that dose-effect of different azide concentrations was not clear. With allele description of detected AFLPs among favorable mutant lines, it was possible to discriminate each mutant line from others which have similar phenotypes and reactions against pathogens. AFLP fingerprinting patterns of waxy mutant lines, otherwise, were highly homogeneous as well as their phenotypic and agronomic characters.

• International Journal of Aerospace System Engineering
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• v.7 no.2
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• pp.1-5
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• 2020

When a rigid wedge is indented in to a semi-infinite block, the material is bulged up around the wedge that is generally called lip. The previous works in this filed considered the outer profile of the lip to be linear. But, present authors observed both experimentally and with the aid of finite element analysis that the profile of the lip is not always linear, and it depends on the angle of the wedge and friction parameters. So, in this work, attempts have been made to calculate hardness of indentation for different wedge angles and friction parameters. As hardness is intrinsic property of material, consideration of either linear or parabolic lip will not be affected much. A comparative study of hardness for linear and parabolic free surface profiles of the piled up material around the cone is analyzed in this work.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.166-168
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• 2015

Line of Balance (LOB) method is suitable to schedule construction projects composed of repetitive activities. Since existing LOB based repetitive project scheduling methods are deterministic, they do not lend themselves to handle uncertainties involved in repetitive construction process. Indeed, existing LOB scheduling dose not handle variability of project performance indicators. In order to bridge the gap between reality and estimation, this study provides a stochastic LOB based scheduling method that allows schedulers for effectively dealing with the uncertainties of a construction project performance. The proposed method retrieves an appropriate probability distribution function (PDF) concerning project completion times, and determines favorable start times of activities. A case study is demonstrated to verify and validate the capability of the proposed method in a repetitive construction project planning.

• Journal of the Korean Geographical Society
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• v.43 no.4
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• pp.638-654
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• 2008

A questionnaire survey is conducted to identify the middle school students' abilities to recognize the proportional symbolic maps. After analyzing the data from the respondents, three facts could be concluded. First, the trends of under-estimation are represented as the power function and the degree of under-estimation is increased as the sequence of line, square, circle, sphere symbols. Second, the estimations of symbol size are effected by the number of symbols in the legend(3, 5, 7), the presentation methods of legends(linear, nested), and the system to scale the symbol size(mathematical, perceptual). Lastly, the size of symbols on the map tends to be over-estimated comparing to the symbols in the legend, and the differences between the first year and third year students to recognize the proportional symbol maps are not identified.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.138-143
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• 2005

During faults, the voltage and current signals available to the relay are affected by the decaying dc component and harmonics. In order to make appropriate and accurate decisions, most of the relaying algorithms require the fundamental frequency phasor information that is immune to decaying dc effect and harmonics. The conventional Fourier ph as or estimation algorithm is affected by the presence of decaying-exponential transients in the fault signal. This paper presents a modified Fourier algorithm, which effectively eliminates the decaying dc component and the harmonics present in the fault signal. The decaying dc parameters are estimated by means of an out-of-band filtering technique. The decaying dc offset and harmonics are removed by means of a simple computational procedure that involves the design of two sets of Orthogonal digital OFT filters tuned at different frequencies and by creating three off-line look-up tables. The technique was tested for different decay rates of the decaying dc component. It was also compared with the conventional mimic plus the full cycle OFT algorithm. The results indicate that the proposed technique has a faster convergence to the desired value compared to the conventional mimic plus OFT algorithms over a wide range of decay rates. In all cases, the convergence to the desired value was achieved within one cycle of the power system frequency.

• Journal of Biomedical Engineering Research
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• v.27 no.3
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• pp.89-93
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• 2006

A simple algorithm that can be used to estimate a healthy person's blood pressure using pulse transit time is proposed in this paper. Fifty healthy students participated in the experiment that was conducted in line with the study. The subjects were asked to exercise on several exercise levels using a bicycle ergometer. Their blood pressures during the succeeding rest period were measured. A simple method was proposed to illustrate the relationship between blood pressure and pulse transit time. The systolic blood pressures as well as the heights and weights of the subjects were regarded as the proper parameters, and a second-order regression curve was produced to estimate the subjects' blood pressures. The mean error of estimation was less than 10 mmHg, which was the mean error of manual measurement. Although our estimation model is so simple, it can be used to estimate continuous blood pressure measurement for bicycle ergometer exercise. The electrocardiograms, photoplethysmograms, and blood pressures, however, could not be measured simultaneously As such, their estimation may be slightly different from the results taken from simultaneous measurements.