• Journal of Powder Materials
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• v.17 no.1
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• pp.44-51
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• 2010

The rheological behavior of a cordierite honeycomb extrusion paste was investigated by measuring torque values in a Brabender plastograph. The extrusion pastes were formulated using binder (methy cellulose, MC), solvent (water), plasticizer (ploy ethylene glycol, PEG) and lubricants (oleic acid, OA). The mixing sequence and optimum organic binder, at least for homogeneous mixed state, can be determined from the rheological point of view. 3%MC-30%$H_2O$-1.5%PEG-1.0%OA with respect to the cordierite powder was chosen as a binder composition for the extrusion process of cordierite powder.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.134-136
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• 2001

In this paper, using equivalent circuit of BLDC motor in the 30W class, process of modeling the BLDC motor and calculating the parameter is shown. Through run-down-test and measuring back EMF, torque, speed and ampere, parameter that transfer function requires was gotten. In this result, for step response of BLDC motor, comparing the actual result obtained by circuit experiment with the simulation result obtained by substituting this parameter into the transfer function, it was established that process calculating parameters in this study is proper.

• Journal of Magnetics
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• v.20 no.1
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• pp.8-10
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• 2015

The magnetic anisotropy field plays an important role in spin-orbit-torque-induced magnetization dynamics with electric current injection. Here, we propose a magnetometric technique to measure the magnetic anisotropy field in nanostructured ferromagnetic thin films. This technique utilizes a magneto-optical Kerr effect microscope equipped with two-axis electromagnets. By measuring the out-of-plane hysteresis loops and then analyzing their saturated magnetization with respect to the in-plane magnetic field, the magnetic anisotropy field is uniquely quantified within the context of the Stoner-Wohlfarth theory. The present technique can be applied to small nanostructures, enabling in-situ determination of the magnetic anisotropy field of nanodevices.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.107-114
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• 2003

The effect of uncertainties caused by measured parameters, which are propagated to the uncertainty of total-to-total efficiency, are analyzed from a turbine performance test. The degree of reaction is 0.373 at the mean radius on a tested 3-D axial type turbine, and the performance test is conducted at the low pressure and cold temperature status. The uncertainty of turbine inlet and exit total pressure shows the strong propagation effect to the uncertainty of total-to-total efficiency. This means that a high precision pressure measuring system is required to reduce the uncertainty propagated by the pressure. In the uncertainty portion of each measured parameters to the uncertainty of total- to-total efficiency, the uncertainty by torque is the highest and the uncertainty by RPM is the lowest. In case of the total pressure, the effect of the uncertainty by torque is increased with the increasing RPM. The uncertainty of total pressure at the turbine exit is more important than that at the turbine exit.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.123-126
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• 2003

The uncertainties generated by measurement parameters are propagated to the uncertainty of total-to-total efficiency on an experiment. The effect of uncertainties’ propagation are analyzed through a turbine performance test. A tested 3-D axial type turbine has a 0.373 degree of reaction at the mean radius and the performance test is conducted at the low pressure and cold temperature status. The uncertainty of turbine inlet and exit total pressure shows the strong propagation effect to the uncertainty of total-to-total efficiency. This means that a high precision pressure measuring system is required to reduce the uncertainty propagated by the pressure. In the uncertainty portion of each measurement parameters to the uncertainty of total-to-total efficiency, the uncertainty by torque is the highest and the uncertainty by RPM is the lowest. In case of the total pressure, the effect of the uncertainty by torque is increased with the increasing RPM. The uncertainty of total pressure at the turbine exit shows more influence to the results than that at the turbine.

• Industrial Engineering and Management Systems
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• v.10 no.3
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• pp.209-220
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• 2011

Self-tapping screws have some operational peculiarities. In spite of their economical advantage that requires no prior tapping operation, a weakness of self-tapping screw-tightening operations is that screws can easily be tightened at a non-right angle, thus resulting in an improper tightening strength. Increases in outsourced workers have reduced labor costs, but the accompanying high worker fluidity means that new workers are more frequently introduced into factories. It is necessary to train new workers for self-tapping screw-tightening operations, which occupies a considerable portion of ordinary assembly works. The purpose of this study is to develop and implement a skill transfer system for the operation. This study (1) proposes a set of characteristic values for evaluating the quality of the operation and develops a device that can measure these values; (2) proposes criteria for evaluating the resultant quality of the tightening; and (3) develops a skill training system for better work performance. Firstly, sets of characteristic values for evaluating the quality of the operation, namely, torque, vertical pressure forces and horizontal vibration forces, are proposed. A device that can measure these values is developed. Secondly, criteria for evaluating the resultant quality of the tightening are identified, involving tightening torque, maximum vertical pressure and timing, vibration area during the processing and tightening period, and work angle. By using such parameters, workers with the proper aptitude can be identified. Thirdly, a skill training system for the operation is developed. It consists of screwdriver operation training and screw-tightening training with feedback information about the results of the operation. Finally, the validity of the training system is experimentally verified using new operators and actual workers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2682-2688
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• 2012

In this paper, we design and implement a electric current controller for ignition coil to measure the amount of current and to supply the additional current under vehicle driving conditions in spark ignition engines. The proposed controller can provide the stable current and prevent the overcurrent by measuring the amperage of primary ignition in real time. Also it enhances the performance of vehicle engine by controling the amount of ignition energy that make power increase and fuel burn more completely. The power and torque of the normal vehicle is evaluated as performance index for the experimental validation of the control module. The experimental results using dynamometer equipment show that after control module-mounted elevates the average of 10% more in both power and torque compared with before module-mounted.

• Geotechnical Engineering
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• v.9 no.4
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• pp.65-82
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• 1993

A series of torsion shear tests were performed to study the drained stress -strain behavior of medium dense Santa Monica Beach sand under various stress paths. The torque was applied to both clockwise and counterclockwise directions at the end of hollow cylinder specimen. Two clip gages had been previously used to measure the changes in wall thickness and diameter of the specimen. In this study, however, the lateral strain was determined by measuring volume changes in specimen. Specimens were prepared by the air pluviation method and gaseous carbon deozide( CO2) was used to measure precisely volumetric strain in specimen. The drained stress -strain behavior of cohesionless Boils during rotation of principal stress directions was analysed based on the results of torsion shear tests. The coupling of mal stress were applied. It was also found from the test results that the atrial strain at failure decreased with increasing value.

• Tribology and Lubricants
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• v.39 no.5
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• pp.203-211
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• 2023

This study experimentally investigates the effects of angular acceleration on the friction and wear performances of a gas foil thrust bearing (GFTB) using a typical GFTB with six pads. The outer radius of the bearing is 31.5 mm, the total bearing area is 2,041 mm² , and the bump foil and incline (ramp) height are both 500 ㎛. The newly developed GFTB test rig for measuring the friction torque and coefficient measures the axial load, drag torque, lift-off speed, and touch-down speed. The experiment is conducted for angular accelerations of 78.5, 314.2, and 328.3 rad/s² at axial loads of 5, 10, and 15 N, respectively. The test shows that the start-up friction coefficient increases with increasing axial load at the same angular acceleration, and the friction coefficient decreases with increasing angular acceleration under the same axial load. As the angular acceleration increases, the lift-off speed at the motor start-up increases, and the touch-down speed at the motor stop decreases. The wear distance of the GFTB for a single on/off cycle increases with increasing axial load at the same angular acceleration and decreases nonlinearly with increasing angular acceleration under the same axial load. The test results suggest that adjusting the rotational angular acceleration helps reduce bearing friction and wear.

• The Journal of Korean Physical Therapy
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• v.17 no.3
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• pp.429-440
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• 2005

The purpose of this study was to compare the effects of knee joint position sense following local and general load protocols in 25 healthy male subjects. Proprioception of the knee joint was evaluated by measuring absolute angular errors at matching angles before, after and between 2 different types of load protocols. Proprioception tests(on the dominant knee) were performed in which proprioception of the passivepassive reproduced and active-active reproduced knee position was measured. Local load was provided with maximum isokinetic knee extension-flexion on the isokinetic dynamometer(Cybex), and general load was 10 minutes running on a treadmill. Peak torque(knee extension and flexion) and heart rate(beats per minute) was evaluated as an indicator of local and general fatigue during load protocols. The results were as follows: 1. For pasive-pasive reproduced knee position test, significant difference in absolute angular errors after general load protocol was detected compared with that before general load protocol(P<.05), significant difference in absolute angular errors after local load protocol was detected compared with that before local load protocol(P<.05). However, no significant difference in absolute angular errors of general load protocol was detected compared with that of local load protocol (P>.05), no significant difference in absolute angular errors of local load protocol was detected compared with that of general load protocol(P>.05). 2. For active-active reproduced knee position test, significant difference in absolute angular errors after general load protocol was detected compared with that before general load protocol(P<.05), significant difference in absolute angular errors after local load protocol was detected compared with that before local load protocol (P<.05). Also, significant difference in absolute angular errors of general load protocol was detected compared with that of local load protocol(P<.05), significant difference in absolute angular errors of local load protocol was detected compared with that of general load protocol(P<.05). 3. A significant decrease of peak torque of knee extensors and flexors was seen after local load, although heart rate was significantly increased(P<.05). No significant change of peak torque of knee extensors and flexors was seen after general load(P>.05), although heart rate was also significantly increased(P<.05). The previous study revealed that knee proprioception is significantly altered when the muscle mechanoreceptors are dysfunctional due to muscle fatigue, although the joint mechanoreceptors have no significantly effect on knee proprioception when the presence of knee muscle fatigue. However, the results of this study are different from those of the previous study in that muscle weakness of the knee could not be seen after general load. This study shows that general load may diminish motor control by the central nervous system. Proprioceptional decline without muscle weakness of knee after general load suggests a change in the proprioceptional pathway without influence from muscle mechanoreceptors.