• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.05a
• /
• pp.867-868
• /
• 2012

• Proceedings of the KIEE Conference
• /
• 2005.11b
• /
• pp.139-141
• /
• 2005

For the reliable evaluation of the distribution and power transformer no-load loss measurement, measurement uncertainty of the transformer measuring system, consisted of current transformer, potential transformer and power metering equipment is required. In this paper, we describe the uncertainty of transformer measuring system based on ANSI/IEEE C57.12.90.

• Journal of Electrical Engineering and Technology
• /
• v.4 no.2
• /
• pp.149-158
• /
• 2009

It is important to derive reliable parameter values in the measurement-based load model development of electric power systems. However parameter estimation tasks, in practice, often face the parameter identifiability issue; whether or not the model parameters can be estimated with a given input-output data set in reliable manner. This paper introduces concepts and practical definitions of the local identifiability of model parameters. A posteriori local identifiability is defined in the sense of nonlinear least squares. As numerical examples, local identifiability of third-order induction motor (IM) model and a Z-induction motor (Z-IM) model is studied. It is shown that parameter ill-conditioning can significantly affect on reliable parameter estimation task. Numerical studies show that local identifiability can be quite sensitive to input data and a given local solution. Finally, several countermeasures are proposed to overcome ill-conditioning problem in measurement-based load modeling.

• International Journal of Railway
• /
• v.8 no.1
• /
• pp.1-4
• /
• 2015

An accurate measurement of the train-track interaction forces is important for track performance evaluation. In the field calibration test as a wheel load measurement process, the calibration system creates a different boundary condition in comparison with that in the train wheel passage. This study aims to evaluate a reliability of the field calibration test in the process of wheel load measurement. Finite element models were developed to compare the deformed shapes, bending moment and shear force profiles on the rail section. The analysis results revealed that the deformed shapes and their associated bending moment profiles on the rail are significantly different in two numerical simulations of the calibration test and the train wheel load passage. However, the shear stress profile on the rail section of the strain gauge installation in the field was almost identical, which may imply that the current calibration test is sufficiently reliable.

• Current Optics and Photonics
• /
• v.2 no.6
• /
• pp.519-524
• /
• 2018

We propose a transverse load sensor with reconfigurable measurement accuracy based on a microwave photonic filter in the $K_u$ band, incorporating a polarization-maintaining fiber Bragg grating. A prototype sensor with a reconfigurable measurement accuracy tuning range from 6.09 to 9.56 GHz/(N/mm), and corresponding minimal detectable load range from 0.0167 to 0.0263 N/mm, is experimentally demonstrated. The results illustrate that up to 40% manufacturing error in the grating length can be dynamically calibrated to the same corresponding measurement accuracy for the proposed transverse load sensor, by controlling the semiconductor optical amplifier's injection current in the range of 154 to 419 mA.

• Journal of the Korean Society of Safety
• /
• v.25 no.3
• /
• pp.83-90
• /
• 2010

In this study, it is conducted that the performance verification of the ambient load carrying capacity algorithm using long-term measurement systems of bridges. For this purpose, a steel-box type model bridge is fabricated and the public load carrying capacity of a steel-box model bridge is estimated by conducting the numerical analysis and load test. In addition, we compare the public load carrying capacity with the estimated result of a steel-box model bridge using the ambient load carrying capacity algorithm. By the assessment result, it is shown that the estimated ambient load carrying capacity is the difference of approximately 6.0 percentages as compared with the public load carrying capacity.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.228-233
• /
• 2004

A derailment coefficient of railway vehicle is as one of important element that estimate running safety. Derailment coefficient is ratio of lateral load/vertical load happens in contact point between wheel and rail. Lateral load increases, dangerous of derailment can rise. There are ground and vehicle to measurement method of these derailment coefficient. Method of ground is simple, but when vehicles passes data of a point, there is shortcoming that acquire locally. Curved surface style wheel shape that use so far among vehicle method in this research wishes to be not but describe about static load test of wheel-set for derailment coefficient measurement that have plane plate shape that manufacture separate way and correction result etc. to test.

• Proceedings of the KIEE Conference
• /
• 2005.04a
• /
• pp.28-30
• /
• 2005

This paper presents a scheme on the characteristics of voltage and current unbalance factor under the load variation at the three phase 4-wire system. The voltage unbalance factor of the three-phase 4-wire system is approved by the field measurement. This system is composed of three one-phase transformer with each other capacity. Current unbalance factor is measured by the power quality measurement apparatus and compared by the load unbalance factor. Each phase has an impedance each other by the unbalanced load operation pattern and give rise to voltage unbalance.

• Transactions of Materials Processing
• /
• v.30 no.4
• /
• pp.172-178
• /
• 2021

The cold forging process induces material deformation in an enclosed space, generating a very high forging load. Therefore, it is mainly designed as a multi-stage process, and fatigue failure occurs in forging die due to cyclic load. Studies have been conducted previously to quantitatively predict the fatigue limit of cold forging dies, however, there was a limit to field application due to the large error range and the need for expert intervention. To solve this problem, we conducted a study on the introduction of a real-time forging load measurement technology and an automated system for quantitative prediction of die life cycle. As a result, it was possible to reduce the error range of the quantitative prediction of die life cycle to within ±7%, and it became possible to use the die life cycle calculation algorithm into an automated system.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.10a
• /
• pp.303-306
• /
• 2008

This study proposes an essential process of type certificate, which is load comparison for proving the calculated design load. The load measurement was carried out according to IEC 61400-13 standard and the load calculation was performed with same condition using FLEX 5 code. For more accurate load simulation, the controller parameter of original model at the design stage was modified to site optimized value and some node points are added to coincidence with measurement. The load comparison was performed with various wind parameter, turbulence intensity and wind shear. As a result, simulated loads ware good agreed with the measured load. Therefore, the calculated design loads according to IEC 61400-1 standard were proved to valid.