• Geomechanics and Engineering
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• v.14 no.6
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• pp.589-600
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• 2018

For foundations in permafrost regions, the displacement characteristics are uncertain because of the randomness of temperature characteristics and mechanical parameters, which make the structural system have an unexpected deviation and unpredictability. It will affect the safety of design and construction. In this paper, we consider the randomness of temperature characteristics and mechanical parameters. A stochastic analysis model for the uncertain displacement characteristic of foundations is presented, and the stochastic coupling program is compiled by Matrix Laboratory (MATLAB) software. The stochastic displacement fields of an embankment in a permafrost region are obtained and analyzed by Neumann stochastic finite element method (NSFEM). The results provide a new way to predict the deformation characteristics of foundations in permafrost regions, and it shows that the stochastic temperature has a different influence on the stochastic lateral displacement and vertical displacement. Construction disturbance and climate warming lead to three different stages for the mean settlement of characteristic points. For the stochastic settlement characteristic, the standard deviation increases with time, which imply that the results of conventional deterministic analysis may be far from the true value. These results can improve our understanding of the stochastic deformation fields of embankments and provide a theoretical basis for engineering reliability analysis and design in permafrost regions.

• Tribology and Lubricants
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• v.35 no.2
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• pp.114-122
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• 2019

High-speed rotating machinery requires low cost and reliable bearing elements with low friction, stable rotordynamic characteristics, and a simple design. This study experimentally evaluates the effects of bearing-support elements on the vibrational characteristics of a small-sized, high-speed permanent magnetic motor. A series of coast down tests from 100 krpm characterize the vibrational behaviors, rotor displacement, and housing acceleration of motors supported by ball bearings, ball bearings with a metal mesh damper, and gas foil bearings, respectively. Two eddy-current sensors installed in the horizontal and vertical directions measure the displacement of the rotor at its front nut, and a 3-axis accelerometer attached to the motor housing measures the housing acceleration. The test results reveal that synchronous (1X) vibration components most significantly affect the rotor displacement and housing acceleration, independent of the bearing-support elements. The motor supported by the deep-groove ball bearings results in the largest rotor vibrations increasing with speed; this is due to the absence of a damping mechanism. Additionally, the metal mesh damper effectively reduces the rotor displacement, housing acceleration, and sound-pressure level in the high-speed region (i.e., above 40 krpm), thus implying its substantial damping performance when installed on the outer race of the ball bearing. Lastly, the gas foil bearing supported motor yields the smallest rotor displacement, housing acceleration, and lowest sound-pressure level because of its hydrodynamic airborne operation, which does not require rolling elements that may cause mechanical friction and vibrations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.235-238
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• 1998

In this study, the cymbal actuators with brass and bronze endcap at various endcap thickness were fabricated, and then the displacement vs applied voltage relation and position from the center of endcap relation were investigated The displacement values of all cymbal actuator were measured using laser vibrometer. The displacement of the cymbal actuator was increased linearly with increasing applied voltage. The cymbal actuator with 0.15mm thick brass endcap show approximately 1.3$\mu\textrm{m}$ displacement more than cymbal actuator with uniformly thick bronze endcap. The displacement about 3mm in diameter at the center of the endcap was uniform and rapidly decreased away from 3mm in diameter at the center of the endcap.

• Journal of Sensor Science and Technology
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• v.16 no.4
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• pp.263-269
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• 2007

Although variable resistance displacement transducer is widely applied for its technical simplicity, electrical point contact limits measurement resolution (precision). The present study introduced roller shaped structure for electrical line contact. Proto-type transducer was developed and measurement characteristics were compared with a commercialized product. When the displacement was varied with steps of 5 mm, 1 mm, and down to 0.1 mm, the correlation coefficient between resistance and displacement decreased lower than 0.9 in the commercialized product while the proto-type transducer maintained values higher than 0.99. Therefore, the measurement resolution was enhanced by approximately 10 times. Since manufacturing also seemed easier, the present results would enable more accurate and less expensive manufacturing of variable resistance displacement transducer.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.35-41
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• 2000

Residual stress is defined as a minimum stress with a large displacement of specimens and the residual stress after peak shear stress appears with displacement volume but there is no provision to select the residual stress. In the previous study, residual stress was recorded when the change of shear load is small in the condition of the strain more than 15%. But, in this study, hyperbolic function((No Abstract.see full/text), b=experimental constant) of soil test is adapted to joint of rock and the propriety is investigated. In a landslide and landsliding of artificial slope, wedge failure of tunnel with a large displacement, tests are simulated from peak stress to residual stress for safety analysis. But now. direct shear stress and triaxial compressive tests are usually performed to find out characteristics of shear stress about joint. Although these tests get a small displacement, that data of peak stress and residual stress are used for safety analysis. In this study, we tried to determine failure criteria for joints of rock using ring shear test machine. The residual stress following shear behavior was determined by the result of ring shear test and direct shear test. In conclusion, after comparing the results of the two test, we found that cohesion(c) and internal friction angle(ø) of ring shear test are 30% and 22% respectively of those of the direct shear test.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.184-185
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• 2014

The purpose of this study is to experimentally evaluate the variation characteristics of stiffness and impact resistance under the construction height of gypsum board wall at the actual construction site. The method suggested in previous study was applied on the test method of horizontal load resistance and impact resistance. As a result of horizontal load resistance test, when the wall height is 2,400 mm, the maximum displacement is 13.6 mm and residual deformation is 0.5 mm, and when the wall height is 3,000 mm, the maximum displacement is 31.3 mm and the residual displacement is 6.8 mm. As a result of impact resistance test, the residual deformation of each specimen at 20 cm of fall height were 1.02 mm and 0.08 mm, respectively, the residual deformation at 40 cm of fall height were 1.58 mm and 0.35 mm, respectively, and the residual deformation at 60 cm of fall height were 2.23 mm and 2.48 mm, respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.1
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• pp.25-32
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• 2007

Automobile manufacturing companies should provide the products and service that can satisfy consumers who usually want various kinds of automobiles. This paper studied the relations among several demographic characteristics(gender, age, occupation, income) of consumers and automobile's attributes(engine performance, engine displacement, price, maintenance expenses, color, etc.) and preferred automobile(kind, size, company, price). For the relation research we established a model and related hypotheses and used a questionnaire survey, where 350 subjects were questioned. After the analysis, many statistically significant results are obtained : consumer's gender has relations with the preference for engine performance, engine displacement, price, color, and design; age has relations with the preference for engine displacement, maintenance expenses, free checking during A/S period, etc., occupation has relations with the preference for engine performance, engine displacement, price, maintenance expenses, fuel efficiency, etc. : income has relations with the preference for engine performance, engine displacement, price, maintenance expenses, mileage, reputation of car manufacturing companies, etc.; price and fuel efficiency has relations with the preference for car manufacturing companies. These results suggest the consumer-oriented sales of automobiles and are expected to be helpful for the effective strategy development of automobile marketing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.10
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• pp.1517-1522
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• 2015

Since electric railroad vehicle pass through repeatedly on the railroad bridge, the dynamic load that causes the change of tension of contact wire affect it constantly. In this paper, we measured the dynamic displacement of the railroad bridges to analyze the effect of tension in the catenary. A result of dynamic measurement of the longitudinal displacement, it's maximum value was 39.9mm which was lower than the primary management criteria 378mm. Also on the based of a maximum temperature, it shows a feature that the longitudinal displacement value increased as temperature rise from April to October. In terms of behavior characteristics of a tensioning device, it was confirmed to be the value of 50mm stroke movement when the temperature changes ±5℃.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.798-803
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• 2006

The suspension elements like primary coil spring, yaw damper, body to body damper are core parts of high speed railway bogie and the faults relating to these elements are reported recently. Thus, this study is started to analyze the displacements characteristics of suspension elements of high speed railway rolling-stock for the purpose of preventing the faults and developing the maintenance technology for suspension elements like spring and dampers. For this purpose, we made a plan to measure the displacements of the primary coil spring, yaw damper and body to body damper in actual running condition. We developed the measurement device to measure the longitudinal displacement and angular displacement of suspension elements and installed this device to test suspension elements. Test to measure displacements of suspension elements is conducted in service line of high speed railway. The displacement data which is acquired from the test with actual vehicles was analyzed for its maximum displacement depending on the track sections. As a result of analysis, we obtained the displacement trends occurring with the sections and valuable results like maximum values and the displacement distribution.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.8
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• pp.880-888
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• 2007

This article describes the load capability of bending piezoelectric actuators with a thin sandwiched PZT plate in association with the stored elastic energy induced by an increased dome height after a curing process. The stored elastic energy within the actuators is obtained via a flexural mechanical bending test. The load capability is evaluated indirectly in terms of an actuating displacement with a load of mass at simply supported and fixed-free boundary conditions. Additionally, a free displacement under no load of mass is measured for a comparison with an actuating displacement. The results reveal that an actuator with a top layer having a high elastic modulus and a low coefficient of thermal expansion exhibits a better performance than the rest of actuators in terms of free displacement as well as actuating displacement due to the formation of the large stored elastic energy within the actuator system. When actuators are excited at AC voltage, the actuating displacement is rather higher than the free displacement for the same actuating conditions. In addition, the effect of PZT ceramic softening results in a slight reduction in the resonance frequency of each actuator as the applied electric field increases. It is thus suggested that the static and dynamic actuating characteristics of bending piezoelectric composite actuators with a thin sandwiched PZT plate should be simultaneously considered in controlling the performance.