• Journal of the Korean Society for Heat Treatment
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• v.13 no.1
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• pp.10-15
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• 2000

Evaluation of long term stability of the Brinell standard hardness tester was carried out to secure its application as a national standard in Brinell hardness. Accuracy and repeatability in load application were tested through evaluating errors in hardness measurement of certified reference blocks. All of those requirements in KS as well as ISO specifications were satisfied by this standard hardness tester. In addition to this, long term stability test of automatic indentation measurement system was carried out. The scattering range was almost the same with its error range. To figure out an optimum test condition for better repeatability and long term stability, the effect of load variation, load application speed and time have been studied using orthogonal array experimental plan. It was found that the best combination is $30{\mu}m/s$ of load application speed and 25 seconds of load application time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.644-653
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• 2018

Landslides occur frequently due to the effects of heavy rainfall and typhoons caused by climate change. Erosion control measures are needed to effectively prevent landslide damage. In order to improve their efficiency, it is necessary to quantitatively measure the sediment discharge from the mountain stream. In this study, a load cell sensor was installed in a mountain stream and the measured values were compared according to the applicability and load test type in the mountain stream. The result of the load test showed that the effect of the loading type (load test 1, 2) was low at average (loadings) of 0.4kgf and 0.6kgf at sites 1 and 2, respectively. The load factor was also derived by regression analysis to increase the accuracy of the measured values. According to the results of the load factor (normalized) to the load-cell measurement value, the output value increased by 14.8% and 24.6% in sites 1 and 2, respectively, and was calculated to be similar to the reference value. The load cell sensor enabled us to quantitatively estimate the amount of sediment discharge in the mountain stream through time series analysis with the water level and rainfall information. If the monitoring is carried out for a long time, it can be used to find the sediment discharge mechanism for the mountain stream. In addition, applying sensors such as load-cells to a mountain stream is expected to contribute to the development of related industries, such as the manufacturing of measurement sensors.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.2
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• pp.45-52
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• 2002

Load modeling is classified into two methods according to approaching method, so called the measurement and component-based method. The measurement method is to model the load characteristics measured directly at substations and feeders. But it is difficult to measure continuously load characteristics from naturally occurring. system variation. The component-based method consists of the fellowing process; component load modeling, composition rate estimation and aggregation of component loads, etc. In this paper, the characteristic experiment of component loads was performed to obtain data for the component load modeling as the component-based method. At first, representative component loads were selected by the proposed method considering the accuracy of load modeling and the performance possibility of component load experiment in the laboratory. Also an algorithm was Proposed to identify the reliability of data obtained from the component load characteristic experiments. In addition, the results were presented as the case studies.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.55-57
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• 2009

This paper deals with an improved core loss calculation under the load conditions, namely, no-load, AC-load and DC-load of multi-pole PM generator from curve fitting method using modified Steinmetz equation considered anomalous loss. For an accurate calculation, magnetic field analyses in stator core considering the time harmonics are performed. And using the nonlinear finite element analysis (FEA), we applied separated rotating and alternating magnetic field to core loss calculation. In order to verify the core loss results by proposed method, the experimental system for no-load core loss measurement has been implemented with DC motor, power analyzer and manufactured PM generator. And, the analysis results with rotational speed agree extremely well with those obtained by measurement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.1
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• pp.111-120
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• 2000

This study discusses the issues related to the accuracy of deflection measurement in the testing of FRC. Some deflection methods may include large extraneous deformations. such as local crushing at the loading points, elastic and inelastic deformations of the loading fixture, etc. A faulty load-deflection curve will be obtained if an unstable deflection measuring system is used, and incorrect toughness evaluation can be reached on the basis of this faulty curve. In this paper, the discussion will focus on the effects of the deflection measuring system on both the measurement of the load-deflection response of FRC and the evaluation of FRC toughness. It is observed that ASTM toughness indices which is based on measuring deflection at first cracking is influenced significantly by extraneous deformation in deflection measurement. But extraneous deformation in deflection measurement result in negligible errors in toughness evaluation using JSCE and JCI definition. However, in order to evaluate toughness accuracy, it is desirable to use net load-deflection curve eliminated extraneous deformation.

• Journal of the Semiconductor & Display Technology
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• v.3 no.2
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• pp.23-26
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• 2004

Thin film is one of the most general structures used in micro-electro-mechanical systems (MEMS). To measure the mechanical properties of SU-8 film, tensile testing was adopted which offers not only elastic modulus but also yield strength and plastic deformation by load-displacement curve. Tensile testing system was constructed with linear guided servo motor for actuation, load cell for force measurement and dual microscope for strain measurement.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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• pp.304-311
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• 2012

So far, the importance for an accurate load model has been constantly raised and its necessity would be further more emphasized. Currently used load model for analysis of power system in Korea was developed 10 years ago, which is aggregated by applying the statistically estimated load compositions to load models based on individual appliances. As modern appliances have diversified and rapidly changed, the existing load model is no longer compatible with current loads in the Korean power system. Therefore, a measurement based load model is more suitable for modern power system analysis because it can accurately include the load characteristics by directly measuring target load. This paper proposes a ZIP model employing a Kalman-filter as the estimation algorithm for the model parameters. The Kamlan-filter based parameter identification offers an advantage of fast parameter determination by removing iterative calculation. To verify the proposed load model, the four-second-interval real data from the Korea Energy Management System (K-EMS) is used.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.6
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• pp.373-380
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• 2020

We have developed the hybrid prototype load cell structures. These developed load cell structures may increase the reliability of the load sensing by deriving the load values through the double sensing method through the vertical maximum deflection and bending stress of the simple beams. For this purpose, the structure design was performed so that the load value, the deflection and stress value could be output to the same value through the optimal structure design. The structurally designed dimensions reaffirmed the accuracy of the design through the structural analysis program and the matching of the load value and the deflection value. Based on the designed structural dimension, the prototype form was constructed through laser cutting and production using hot rolled steel materials. The developed prototype load cell structure can be used as good educational material in various subjects such as material mechanics, steel structure design, measurement engineering, and mechatronics engineering. It is also believed that the measurement system ideas can inform the occurrence of errors in the event of a problem, and if a major accident caused by a sensing error is predicted, it will show good utilization to prevent accidents.

• Journal of Environmental Science International
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• v.23 no.2
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• pp.323-330
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• 2014

Transport of bed load and suspended particle in coastal waters is main factor causing change in shoreline, and effective measurement method and appropriate equipment is required. To measure bed load and suspended particle transport an equipment was designed and manufactured, and it was applied in the field. The equipment consists of four main elements, body supporter, bed load and suspended particle sampler, sampler support and lock. Eight samplers were installed along the circumference of each supporter, and each sample is a 45-degree intervals. The field experiment was done once along Gyeongpo beach in August 2013. This note described the design and function of the equipment and results of field experiments.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.1
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• pp.47-53
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• 2005

Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating voltage unbalance. Voltage unbalance factor is mainly affected by load system rather than stable power system. Unbalanced voltage will draw a highly unbalanced current. As a result, the three-phase currents may differ considerably, thus resulting in an increased temperature rise in the machine. 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. Load unbalance factor is measured by the power quality measurement apparatus and compared by the current unbalance factor. Two methods are indicated similar results. The voltage unbalance factor of the three-phase 4-wire system is approved by the field measurement. Each phase has an impedance each other by the unbalanced operation pattern and give rise to voltage unbalance.