• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.460-466
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• 2018

For the efficient energy consumption in an urban railway station, it is necessary to know the patterns of electrical loads for each usage in detail. The electrical loads in an urban railway station have different characteristics from other normal electrical load, such as the peak load timing during a day. The lighting, HVAC, communication, and commercial loads make up large amount of electrical load for equipment in an urban railway station, and each of them has the unique specificity. These loads for each usage were estimated without measuring device by the polynomial regression method with big data such as total amount of electrical load and weather data. In the simulation with real data, the optimal polynomial regression model was third order polynomial regression model with 9 or 10 independent variables.

• Journal of Drive and Control
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• v.16 no.2
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• pp.1-7
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• 2019

Jaw crusher is a device that breaks rock collected from mines or quarries to produce aggregates of the size desired by user. A representative method for measuring load is to measure them by attaching force sensors directly to the part where the load is generated. However, the direct method has many limitations such as high-impact loads generation in equipment or space constraints, sensor capacities and costs. Therefore, Transfer Path Analysis (TPA) was used to indirectly measure impact loads by attaching acceleration sensors. In this study, both direct and TPA methods were used to measure the impact load of Jaw crusher. This study finally quantifies the impact of the load generated by the Jaw crusher using direct method and TPA method, and comparing the impact load measured calculated the derive the error rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.723-728
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• 2010

This study proposed a design of a portable device for measuring heart rate using photoplethysmograph signal to minimize load of a nurse increased from insufficiency of an internal hospital nurse, and algorithm to measure reliable heart rate in PPG signals despite the existence of patient's motion artifacts. The proposed method for measuring heart rate is the method to minimize the motion interference by using the adaptive filter based on harmonic characteristic of PPG signal. To evaluate the performances of the a portable device implemented by the proposed method, we used several motion artifacts including finger and wrist movements; we then compared out results with the performance of the moving average filter. In this results, the proposed method showed a better performance than that of the moving average filter. Therefore, when nurses use the a portable device for measuring heart rate proposed in this study, it will enable to improve nurse work and to measure the reliable heart rate.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.84-92
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• 2001

Commercial eddy current dynamometers control the torque of rotating body, power supply machine, with the field coil current being operated as a braking force. In this paper, we studied the relation between field coil current and 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 a torque meter which is installed at the case of dynamometer and the multiplied shaft rpm by the squares of field coil current (N$\times$I$^2$). 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 the eddy current dynamometer. This result shows a possibility that eddy current dynamometer can measure the torque of rotating body without a torque measuring device. such as load cell.

• Structural Engineering and Mechanics
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• v.63 no.6
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• pp.771-777
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• 2017

The applications of smartphones or other portable smart devices have dramatically changed people's lifestyle. Researchers have been investigating useage of smartphones for structural health monitoring, earthquake monitoring, vibration measurement and human posture recognition. Their results indicate a great potential of smartphones for measuring pedestrian-induced loads like walking, jumping and bouncing. Smartphone can catch the device's motion trail, which provides with a new method for pedestrain load measurement. Therefore, this study carried out a series of experiments to verify the application of the smartphone for measuring human-induced load. Shaking table tests were first conducted in order to compare the smartphones' measurements with the real input signals in both time and frequency domains. It is found that selected smartphones have a satisfied accuracy when measuring harmonic signals of low frequencies. Then, motion capture technology in conjunction with force plates were adopted in the second-stage experiment. The smartphone is used to record the acceleration of center-of-mass of a person. The human-induced loads are then reconstructed by a biomechanical model. Experimental results demonstrate that the loads measured by smartphone are good for bouncing and jumping, and reasonable for walking.

• Journal of the Korean Geotechnical Society
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• v.39 no.6
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• pp.21-30
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• 2023

One of the methods for calculating unit skin friction of soft-rock-socket parts for cast-in-place piles involves the roughness measurement of the parts. The measurements are conducted during the excavation stage. A roughness measuring device is installed in the excavation hole and the unit skin friction is calculated from the measured surface roughness of the rock socket. Herein, the results of roughness measurement of rock-socket parts in cast-in-place piles and that of load transfer tests are analyzed and compared. The unit skin friction from the roughness measurements can be converted into unit skin friction corresponding to the displacement of a pile generated in a load transfer test. A reduction factor is given as R_f = -0.14n + 1.48.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.156-159
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• 2005

The outer race of CV(constant velocity) joint is an important load-supporting automotive put that transmits torque between the transmission gear box and driving wheel. The outer race is difficult to forge because its shape is very complicated and the required dimensional tolerances are very small. To guarantee the dimensional accuracy of the forged CV Joint, the quick and precise measurement is required to increase the inspection speed of forged products. Therefore in this study, PP(Pre-Position) Device to decrease the inspection time of measuring system has been developed to cope with forging cycle time. The measured inspection time confirms that the PPD is very effective in decreasing inspection time.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.527-532
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• 2012

Recently, in power system, even though the needs of protective IED(Intelligent Electronic Device) is highly increased, there are some problems in the field when use the IED. When the IED is in the fluctuated overload condition, because of the existing algorithm calculate the trip time only with the measured current of just previous measuring stage, the calculated trip time is not a proper value for the overload protection at this kind of condition, and when the load current fluctuate between overload and normal condition, because of the instantaneous reset characteristic of existing algorithm the IED dose not trip. And the non linear loads using power electronic elements seem to be increased. These non linear loads require a counterplan about various harmonics incoming to electric power systems. So we will give solutions about these problems.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.5
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• pp.29-36
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• 2019

In modern society in which the fourth industrial revolution has come to the fore and rapid technology innovations are taking place, a phenomenon of making and selling small quantities of various products that consumers want instead of mass producing one item has emerged. As the market is moving toward the multi-item small-sized production system, there is a need for a system in which a machine independently judges and carries out machining and post-processing. In order for a machine to judge processing on its own, it is necessary to measure the force applied to a product. This study aimed to develop a large-scale dynamometer that enables three-axis measurement using octagonal ring load cells. As for the device's configuration, four octagonal ring load cells, which were previously researched, were used to enable three-axis measurement. It was reconfigured by modifying the attachment position of the octagonal ring load cells' strain gauge and the Wheatstone bridge of each axis, and a system was set up to allow the monitoring of data measured through the monitor. The configured device calculated a strain rate by an experiment, and this rate was compared with the theoretical strain rate to find a correction value. The correction value was entered into a formula, deriving a modified formula. The modified formula was entered into the device, which completed the large-scale dynamometer.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.207-212
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• 2017

The cables installed to deliver high electric power from a generator at a thermoelectric power station are XLPE (or CV) cables. Depending on the installation and usage conditions, the cables in operation start deteriorating from the time of initial operation. Some cables can cause accidents due to faulty construction or other environmental factors. In order to prevent cable accidents, regular auditing of power cables is required. We have invented a measuring device for systematic surveillance and prevention of accidents, and installed the device at Korean Western Power Co. Ltd. which measures load currents through the cables. In this paper, we present the load current measured using our device, analyze the load characteristics by measures current, compare the ampacity defined by IEC standard, and present a basic data to obtain the temperature of cable conductors.