• Water for future
• /
• v.25 no.4
• /
• pp.87-95
• /
• 1992

The validity of the estimate of runoff depth and peak runoff by the basin runoff curve numbers(CN-II for AMC-II condition and CN-III for AMC-III condition) obtained from hydrologic soil-cover complexs is investigated by making use of the observed curve numbers(median curve number and optimum curve number) computed from rainfall-runoff records. For gaged basins the median curve numbers are recommended for the estimation of runoff depth and peak runoff. For ungaged basins, found is that for the estimate of runoff depth CN-III is adequate and for the peak runoff CN-II is adequate. Also investigated is the variation of curve numbers during rainfall, which is turned out to improve the estimates of both depth and peak of runoff.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.24 no.3
• /
• pp.365-371
• /
• 2016

The electromechanical brake (EMB) is one of future brake systems due to its many advantages. For implementation of the EMB, the correct feed back about clamping force is necessary. Keeping commercialization of the EMB in mind, it is strongly demanded that an expensive load cell measuring the clamping force is replaced with an estimation algorithm. In addition, an estimation of the kissing point where the brake pads start to come into contact with a disk wheel is proposed in this paper. With these estimation algorithms, the clamping force can be expressed as a polynomial characteristic curve versus the motor angle. Also, a method for calibration of measured values by the load cell is proposed and used for an actual characteristic curve. Lastly, the performance of the proposed algorithms is evaluated in comparison with the actual curve on a developed EMB test bench.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.15 no.2
• /
• pp.123-135
• /
• 2011

In this paper, we present arc-length estimations for quadratic rational B$\acute{e}$zier curves using the length of polygon and distance between both end points. Our arc-length estimations coincide with the arc-length of the quadratic rational B$\acute{e}$zier curve exactly when the weight ${\omega}$ is 0, 1 and ${\infty}$. We show that for all ${\omega}$ > 0 our estimations are strictly increasing with respect to ${\omega}$. Moreover, we find the parameter ${\mu}^*$ which makes our estimation coincide with the arc-length of the quadratic rational B$\acute{e}$zier curve when it is a circular arc too. We also show that ${\mu}^*$ has a special limit, which is used for optimal estimation. We present some numerical examples, and the numerical results illustrates that the estimation with the limit value of ${\mu}^*$ is an optimal estimation.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.4
• /
• pp.590-597
• /
• 2011

The IDRS provides detection, classification and bearing/range estimation by performing wavefront curvature analysis on an intercepted active transmission from target. Especially, a estimate of the target bearing/range that significantly affects the optimal operation of own submarine is required. Target bearing/range can be estimated by wavefront curvature ranging which use the difference of time arrival at sensors. But estimation ambiguity occur in bearing/range estimation due to a number of peaks caused by high center frequency and limited bandwidth of the intercepted active transmission and distortion caused by noise. As a result the bearing/range estimation performance is degraded. To estimate target bearing/range correctly, bearing/range estimation method that eliminate estimation ambiguity is required. In this paper, therefore, for wavefront curvature ranging, NLS cost function with curve fitting method is proposed, which provide robust bearing/range estimation performance by eliminating estimation ambiguity. Through simulation the performance of the proposed bearing/range estimation methods are verified.

• Smart Structures and Systems
• /
• v.4 no.3
• /
• pp.279-290
• /
• 2008

The modeling and parameter estimation of a damped one-degree-of-freedom mass-spring system is examined. This paper presents a method for estimating the system parameters (damping coefficients and natural frequency) from measured free-vibration motion of a system that is modeled to include both subcritical viscous damping and kinetic Coulomb friction. The method applies a commercially available least-squares curve-fitting software function to fit the known solution of the equations of motion to the measured response. The method was tested through numerical simulation, and it was applied to experimental data collected from a laboratory mass-spring apparatus. The mass of this apparatus translates on linear bearings, which are the primary source of light inherent damping. Results indicate that the curve-fitting method is effective and accurate for both perfect and noisy measurements from a lightly damped mass-spring system.

• Journal of Korea Water Resources Association
• /
• v.40 no.10
• /
• pp.823-832
• /
• 2007

In this study, the separation of short and long durations for estimation the parameters of IDF curve is suggested by using Multi-Objective Genetic Algorithm (MOGA). Objective functions are to minimize root mean squared error (RMSE) and relative RMSE between observed and computed values. The criteria for separation are two; the first one is to estimate more precisely the parameters of IDF curve and the second is to make a single IDF curve without non-continuous duration point. For this purpose 22 rainfall recording gauges operated by Korea Meteorological Administration are selected and three IDF curves that are used generally in South Korea are tested. The result shows that the IDF curve developed by Heo et al. (1999) would be the best of three tested IDF curves, and the suggested parameter estimation method using MOGA can compute more reliable parameters compared with empirical regression analysis.

• Journal of Animal Science and Technology
• /
• v.49 no.2
• /
• pp.195-202
• /
• 2007

The growth traits in swine are economically important, which are measured by gain in weight during test period or by age of days to certain weight. However, the difference in growth rate due to individual performance and also other factors occurs. The more reasonable estimation of the measurements of these traits provides the less error in genetic evaluation of pigs. The data from 1,576 heads being weighed periodically of Gyungnam-heugdon(Berkshire) were analyzed to estimate the growth curve which is used to decide average daily gain and days to 90kg. It may not be possible to directly compare accuracy between the conventional methods and the alternative methods. However, the alternative methods by growth curve would be superior to the conventional methods not only in theoretical background, but also in acceptability for diverse factors such as breed, sex and age. The theoretical superiority of the alternative methods comes from estimation at same age in daily gain and calculation of additional days from measuring date to days to 90kg by growth curve of individual. Also this can be easily adopted in a computer system according to breed and sex.

• Journal of the Korean Magnetic Resonance Society
• /
• v.9 no.2
• /
• pp.93-102
• /
• 2005

Purpose: To develop an advanced non-linear curve fitting (NLCF) algorithm for dynamic susceptibility contrast study of brain. Materials and Methods: The first pass effects give rise to spuriously high estimates of $K^{trans}$ in voxels with large vascular components. An explicit threshold value has been used to reject voxels. Results: By using this non-linear curve fitting algorithm, the blood perfusion and the volume estimation were accurately evaluated in T2*-weighted dynamic contrast enhanced (DCE)-MR images. From the recalculated each parameters, perfusion weighted image were outlined by using modified non-linear curve fitting algorithm. This results were improved estimation of T2*-weighted dynamic series. Conclusion: The present study demonstrated an improvement of an estimation of kinetic parameters from dynamic contrast-enhanced (DCE) T2*-weighted magnetic resonance imaging data, using contrast agents. The advanced kinetic models include the relation of volume transfer constant $K^{trans}\;(min^{-1})$ and the volume of extravascular extracellular space (EES) per unit volume of tissue $\nu_e$.

• Journal of Wetlands Research
• /
• v.14 no.4
• /
• pp.637-644
• /
• 2012

The discharge estimation that means the most important element in a wetlands ecosystem and rivers is a prime concern. All the interim, this discharge estimation depends on stage-discharge curve, but the limitation of stage-discharge curve that uses only connection between the stage and discharge is widely well known. Thus, this paper proposed a method of discharge estimation in a section through "representative parameter estimation method" by using Manning and Chezy equations that have been extensively used in an open channel. Each result is presented by both RMSE and Discrepancy Ratio. The scale difference for the results between laboratory and natural open channel data existed, but the each result showed that the estimated discharge agree with the measured discharge. If the verification and improvement are conducted in various rivers through continuous study, the easy and rapid discharge estimation will be possible. So, the proposed method will be utilized in the water resources fields.

• Bulletin of the Korean Mathematical Society
• /
• v.36 no.1
• /
• pp.15-23
• /
• 1999

We obtain an efficient upper bound of the area of convex curves of constant relative breadth in the Minkowski plane. The estimation is given in terms of the Minkowski are length of pedal curve of original curve.