• Journal of Korea Water Resources Association
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• v.43 no.8
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• pp.695-707
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• 2010

The frequency and size of typhoon and local severe rainfall are increasing due to the climate change and the damage also increasing from typhoon and severe rainfall. The flood forecasting and warning system to reduce the damage from typhoon and severe rainfall needs forecasted rainfall using radar data and short-term rainfall forecasting model. For this reason, this study examined the applicability of short-term rainfall forecast using translation model with weather radar data to point out that the utilization of flood forecasting in Korea. This study estimated the radar rainfall using Least-square fitting method and estimated rainfall was used as initial field of translation model. The translation model have verified accuracy of forecasted radar rainfall through the comparison of forecasted radar rainfall and observed rainfall quantitatively and qualitatively. Almost case studies showed that accuracy is over 0.6 within 4 hours leading time and mean of correlation coefficient is over 0.5 within 1 hours leading time in Kwanak and Jindo radar site. And, as the increasing the leading time, the forecast accuracy of precipitation decreased. The results of the calculated Mean Area Precipitation (MAP) showed forecast rainfall tend to be underestimated than observed rainfall but the correlation coefficient more than 0.5. Therefore it showed that translation model could be accurately predicted the rainfall relatively. The present results indicate that possibility of translation model application of Korea just within 2 hours leading forecasted rainfall.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.68-74
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• 2001

A lane detection based on a road model or feature all needs correct acquirement of information on the lane in an image. It is inefficient to implement a lane detection algorithm through the full range of an image when it is applied to a real road in real time because of the calculating time. This paper defines two (other proper terms including"modes") for detecting lanes on a road. First is searching mode that is searching the lane without any prior information of a road. Second is recognition mode, which is able to reduce the size and change the position of a searching range by predicting the position of a lane through the acquired information in a previous frame. It allows to extract accurately and efficiently the edge candidate points of a lane without any unnecessary searching. By means of inverse perspective transform which removes the perspective effect on the edge candidate points, we transform the edge candidate information in the Image Coordinate System(ICS) into the plan-view image in the World Coordinate System(WCS). We define a linear approximation filter and remove faulty edge candidate points by using it. This paper aims at approximating more correctly the lane of an actual road by applying the least-mean square method with the fault-removed edge information for curve fitting.e fitting.

• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.388-393
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• 1999

In this study, the $CaSO_4:Eu$ TLDs are fabricated and their trap parameters are determined. The optimum concentration of Eu for fabrication of the $CaSO_4:Eu$ TLD is 0.5 mol% and optimum temperature is $600^{\circ}C$ for 2 hours sintering in air. The glow curve of $CaSO_4:Eu$ consists of two glow peaks and these peaks are isolated by thermal bleaching method. Trap parameters of two glow peaks are measured using the initial rise, the peak shape, the heating rate and the least square curve fitting methods. The activation energies of the glow peak I and II are 1.00 eV and 1.09 eV, and the frequency factors are $7.04{\times}10^{11}\;s^{-1}$ and $5.12{\times}10^{11}\;s^{-1}$ and the kinetic orders are 1.11 and 1.33, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1448-1454
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• 2018

In an optical observing system, three pairs of observations at equal time intervals are required for the orbit determination method to obtain orbital information of an unknown space objects. In this paper, we propose a method of estimating a streak for acquiring three pairs of observations using one streak image information. Satellite trajectory simulation data were generated for nine cases using the STK program in order to verify the characteristics of the orbit of space object and estimation performance. Simulation was performed by applying three approaches that can estimate the next streak position after a few seconds from one streak image information, and the estimation performance was evaluated. Linear vector method and Kalman Filter method based on the linear assumption tend to increase the estimation error in the region where the nonlinearity is large. However estimation method using the polynomial curve fitting based on the least square method showed smaller and uniform error result than the previous methods.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.61.3-61.3
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• 2019

The epochs of observation for the 28 determinative stars in the Shi Shi Xing Jing and Cheonsang Yeolcha Bunyajido are estimated by using two fitting methods. The coordinate values in these tables were thought to be measured with meridian instruments, and so they have the axis-misalignment errors and random errors. We adopt a Fourier method, and also we devise a least square fitting method. We do bootstrap resamplings to estimate the variance of the epochs. As results, we find that both data sets were made during the 1^st century BCE or the latter period of the Former Han dynasty. The sample mean of the epoch for the SSXJ data is earlier by about 15-20 years than that for the Cheonsang Yeolcha Bunyajido. However, their variances are so large that we cannot decide whether the Shi Shi Xing Jing data was formed around 77 BCE and the Cheonsang Yeolcha Bunyajido was measured in 52 BCE. We need either more data points or data points measured with better precision. We will discuss on the other 120 coordinates of stars listed in the Shi Shi Xing Jing.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.845-852
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• 2012

The diaphragm-type stylus probe was developed for ultra-precision on-machine measurement (OMM) application. This probe is equipped with two diaphragms which are parallel and one capacitive sensor is used for detecting the vertical motion of end tip in the stylus when it is contacted to the optical freeform surface. For better performance of proposed probes, several design parameters such as axial stiffness and the lateral deformations were investigated with finite element analysis techniques. To verify the feasibility, the profiles of the master sphere ball were measured on the ultra-precision milling machine. The measurement results show that the proposed probe can calculate the radius of the circle within the accuracy of 0.1 ${\mu}m$ for the ultraprecision optical surface.

• The Journal of Korea Robotics Society
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• v.6 no.4
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• pp.334-343
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• 2011

This paper presents a new approach for mobile robot heading detection using MEMS Gyro north finding method in the indoor environment. Based on this, the robot heading angle measurement scheme is proposed; improved north finding theory and algorithm are also explained. Several approaches are applied to confirm system's precision and effectiveness. In order to find out the heading angle, a single axis MEMS gyroscope to sense the angle between the robot heading direction and the north is used. To reach enough estimation accuracy and reduce detection time, the least square method (LSM) for the signal fitting and parameter estimation is applied. Through a turn-table, we setup a carouseling system to decrease the substantial bias effect on gyroscope's heading angle. For the evaluation of the proposed method, this system is implemented to the Pioneer robot platform. The performance and heading error are analyzed after the test. From the simulation and experimental results, system's accuracy, usefulness and adaptability are shown.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.3
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• pp.149-152
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• 1988

Postweaning performances of steer from 11 to 18 months of age under intensive feedlot condition were examined in Brahman and Santa Gertudis cattle breeds which have been established in Paraguay. Fitting of growth data in each breed to an empirical growth model with non-linear least square analysis resulted in the following age(t; months) - weight(w; kg) function made out each breed: w=638.26($1-2.341e^{-0.010965t}$) for Brahman and w=716.38($1-2.365e^{-0.10741t}$) for Santa Gertrudis. The estimated mature size of Brahman steers(638 kg) was 11% lower than that of Santa Gertrudis steers(716 kg). However, slightly larger k value (rate of maturing) of Brahman steer in the mechanistic model suggested relatively earlier maturing tendency in the breed. No significant differences in dressing percentage (Brahman, 59.3%; Santa Gertrudis, 58.8%) of chilled carcass weight to live-weight were observed between breed.

• Wind and Structures
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• v.9 no.6
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• pp.441-455
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• 2006

A more applicable optimization model for extracting flutter derivatives of bridge decks is presented, which is suitable for time-varying weights for fitting errors and different lengths of vertical bending and torsional free vibration data. A stochastic search technique for searching the optimal solution of optimization problem is developed, which is more convenient in understanding and programming than the alternate iteration technique, and testified to be a valid and efficient method using two numerical examples. On the basis of the section model test of Sutong Bridge deck, the flutter derivatives are extracted by the stochastic search technique, and compared with the identification results using the modified least-square method. The Empirical Mode Decomposition method is employed to eliminate noise, trends and zero excursion of the collected free vibration data of vertical bending and torsional motion, by which the identification precision of flutter derivatives is improved.

• Journal of Welding and Joining
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• v.11 no.3
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• pp.22-33
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• 1993

Arc sensor is indispensable to arc welding robot systems for compensating the joint misalignment such as mismatch of the workpiece, ill-conditioned positioner and thermal deformation during welding. Furthermore, the amount of these mismatches cannot be preivously expected, and changes from time to time. There are many kinds of seam trackers for correcting the welding path of the robot, where non-contact type sensors arc prevalently used in arc welding robot systems. In this study, an arc sensor was developed for GMA and FCA welding robot system. Since the arc sensor uses the arc characteristics during welding, the operating principle of the arc sensor must be adjusted according to the welding condition. Especially in GMA welding with the $CO_{2}$ shielding gas, the welding arc is not stable because of the short circuit and non-axial globular transfer mode of the molten droplet. In this study, the 2nd order least square curve fitting algorithm was adopted and the applicability of this algorithm was investigated for robot welding systems. For easy usage of the arc sensor, the operating parameters for arc sensor were limited to eight which can be easily determined by the operator.