• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.66-72
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• 2000

Commercial eddy current dynamometers control the torque of ratating body (poer supply machine) with the field coil current being operated as a braking force. In this paper, we studied about the relation between the field coil current and the torque load of eddy current dynamometer. By the torque measuring analysis of eddy current dynamometer, it is linear relation between the brake force measured from the torque meter (e.g. load cell, strain gage or spring balance etc.) which is installed at the case of dynamometer and the multiply of shaft rpm by the square of field coil current (N$\times$Ia2). To prove the relation, it was experimented and showed that the torque operated by the rotating body can be measured with the shaft rpm and the field coil current of eddy current dynamometer. This result shows a possibility that eddy current dynamometer can measures the torque of rotating body without special torque measuring devices.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.149-156
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• 2002

Field measurements were carried out in this study to investigate the behavior of cut and cover tunnel such as the distribution and the magnitude of the earth pressure during back fill process of the ground material. Three kinds of measuring instruments, such as the earth pressure load cell, the concrete strain gauge and the reinforcing bar meter of embedded type in concrete structure were installed and measured. Earth pressure load cells, installed after construction of the tunnel lining, measure the outside forces acting on the tunnel lining with radial directions. Three load cells were installed at the crown, the right and the left shoulder of the tunnel, respectively. Three sets of reinforcing bar meter were installed in the double reinforcements of the tunnel lining and their locations were the same with the position of the earth pressure load cells. Concrete strain gauge was installed only one site of the upper compressive part at the tunnel crown. Based on the measuring results in the field, the deformation and the earth pressure acting on the tunnel lining were investigated with the back fill process of the ground material. Considerations on the validity of the measuring results were paid. For the analysis of measurements, after dividing back fill process into three steps, various factors which affect on the behavior of tunnel lining were investigated at each step.

• 한국도로학회논문집
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• 제17권1호
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• pp.51-58
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• 2015

PURPOSES : The objective of this study is to compare the densities of asphalt pavements measured both in the field and in the laboratory, and also to evaluate the applicability of field density measuring equipment, such as the pavement quality indicator (PQI), by using statistical analysis. METHODS : For the statistical analysis of the density measured from asphalt pavement, student t-tests and a coefficient of correlation are investigated. In order to compare the measured densities, two test sections are prepared, with a base layer and an intermediate layer constructed. Each test section consists of 9 smaller sections. During construction, the field densities are measured for both layers (base and intermediate) in each section. Core samples are extracted from similar regions in each section, and moved to the laboratory for density measurements. All the measured densities from both the field and laboratory observations are analyzed using the selected statistical analysis methods. RESULTS AND CONCLUSION : Based on an analysis of measured densities, analysis using a correlation coefficient is found to be more accurate than analysis using a student t-test. The correlation coefficient (R) between the field density and the core density is found to be very low with a confidence interval less than 0.5. This may be the result of inappropriate calibration of the measuring equipment. Additionally, the correlation coefficient for the base layer is higher than for the intermediate layer. Finally, we observe that prior to using the density measuring equipment in the field, a calibration process should be performed to ensure the reliability of measured field densities.

• 한국정밀공학회지
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• 제12권4호
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• pp.119-126
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• 1995

This paper presents a non-contact measuring system using one point measuring method to measure surface profiles of dies and clay models for practical use in the field of production engineering. The system has a laser beam probe similar to a measuring probe in a contact measuring system and CCD linear sensor used to detect 300mm measurement range, displacement of measured surfaces, from an origin. There is no mechanical interference between this measuring system and a measured surface in this system. In this measuring system, it was needed 500-600ms including data processing time to measure one point. The experiments showed that the standard deviation was 800 .mu.m and the reproducibility was also 100-210 .mu. m.

• 한국자기학회지
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• 제12권4호
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• pp.149-153
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• 2002

지구자기장 이하의 저자기장 측정에 있어서 소형이고 소비전력이 작으면서 장기적 안정성이 요구되는 분야에 flux-gate 마그네토미터를 많이 사용하고 있다. 또한 많은 저자기장 측정분야가 지구자기장의 크기측정보다는 지자장의 변화를 측정하는 경우가 많기 때문에, 본 연구에서 측정범위가 $\pm$1,000 nT, 5pT/√Hz (at 1 Hz)인 flux-gate센서를 사용 $\pm$50000 nT인 지구자기장을 순차적 근사법으로 보상한 후 지구자기장의 변화를 고감도로 측정할 수 있는 3-축의 flux-gate 마그네토미터를 개발하였다.

• 대한전기학회논문지
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• 제40권6호
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• pp.630-637
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• 1991

For the measurement of time-varying electric fields and related quantities, a field sensor should be sensitive to the field to be measured, and also designed having an accurate transfer function. In this paper, a theoretical model which adequately describes the operation principle and design of the sensor is presented. A calibration and/or correction technique of the sensor is also studied which enables a precise determination of the response of the sensor to an electric field. As a result, the developed electric field sensor and measuring system are known to be accurate within a bandwidth from a few Hz to 200 MHz. It is found that the sensor can be used directly in the measurement of very fast transient voltages and time-varying electric fields occurring during disconnector operations in a gas-insulated substation. It may be useful also for the study on the electromagnetic environmental parameters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.218-221
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• 2008

Due to a variable noises in the field underground lines, clear technology of noises is very important in the diagnosis technology of partial discharge. Therefore we progressed filter test to improve the measuring test of partial discharge in a field. We applied to field test after making W-LC filter for partial discharge measurement, and then designed experimental environment such as under- ground distribution lines of field. Measuring sensor for test was UHF sensor. And we analysed those using the Lemke Probe and oscilloscope (TDS-3054, Tektro- nix). Finally, we obtained excellent data of noise decrement in the joint box of 22.9[kV] distribution lines from above experiment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.826-829
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• 2008

In a field measurement, measurement errors are produced by measuring environments and systematic errors in the measurement procedure. Measurement errors can be expressed as a measurement uncertainty. In this study, the measurement uncertainty and various measuring factors are investigated in heavy-weight impact sounds. According to KS 2810-2, the model functions, which is the estimation of the maximum SPL measurement in each octave band frequency, are determined. From this estimation model, 3.53dB is shown in 63Hz. This level is caused by the sound field of the receiving room, which does not meet the diffusing field.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기설비전문위원
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• pp.72-74
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• 2007

Due to a variable noises in the field underground lines, clear technology of noises is very important in the diagnosis technology of partial discharge. Therefore we progressed filter test to improve the measuring test of partial discharge in a field. We applied to field test after making W-LC filter for partial discharge measurement, and then designed experimental environment such as underground distribution lines of field. Measuring sensor for test was UHF sensor. And we analysed those using the Lemke Probe and oscilloscope (TDS-3054, Tektronix). Finally, we obtained excellent data of noise decrement in the joint box of 22.9[kV] distribution lines from above experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2277-2279
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• 2005

Due to a variable noises in the field underground lines, clear technology of noises is very important in the diagnosis technology of partial discharge. Therefore we progressed filter test to improve the measuring test of partial discharge in a field. We applied to field test after making W-LC filter for partial discharge measurement, and then designed experimental environment such as under-ground distribution lines of field. Measuring sensor for test was UHF sensor. And we analysed those using the Lemke Probe and oscilloscope (TDS-3054, Tektronix). Finally, we obtained excellent data of noise decrement in the joint box of 22.9[kV] distribution lines from above experiment.