• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.357-366
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• 2008

This study addresses the analysis of the behavioral characteristics of bridge expansion joints under wheel loading through wheel load test and the proposal of relevant wheel load specifications for expansion joints. To that goal, specimens of rail and finger expansion joints that are widely used in Korea were fabricated and subjected to static wheel load test using a real tire wheel. The wheel load distribution factor in the rail and finger expansion joints in contact with the wheel load was evaluated. The evaluation revealed that the portion of load sustained by the central rail of rail expansion joint was decreasing with larger wheel load, and that the portion of load sustained by the finger expansion joint was practically insensitive to the increase of the contact area and remained nearly constant. Since the wheel load characteristics showed large difference compared to former design specifications, it appears necessary to prepare rational specifications relative to the distribution of the wheel load contact pressure for the design of expansion joints.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.928-942
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• 2020

The pressure responsiveness property of a skirt-cushion system, which is closely related to the overall performance of Air Cushion Vehicles (ACVs), has always been the difficulty and challenging problem involving cushion aerodynamics and flexible skirt dynamics. Based on a widely used bag and finger skirt-cushion system, the pressure responsiveness properties are investigated numerically. The physical process and mechanism are analyzed and a numerical method for evaluating the pressure responsiveness property is proposed. A cushion-skirt information communication platform is also presented for interchanging the force and the skirt configuration between cushion aerodynamics and flexible skirt dynamics. The pressure responsiveness of a typical skirt-cushion system is calculated and the results demonstrate that the pressure responsiveness property helps alleviate the influence of the cushion height changing on the overall performance of ACVs. Finally, the influences of skirt geometrical and cushion aerodynamic parameters on the pressure responsiveness properties are discussed systematically, giving insight into the design of skirt-cushion systems.

• Progress in Superconductivity and Cryogenics
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• v.18 no.3
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• pp.30-34
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• 2016

An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.369-377
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• 2003

Since Zr-2.5Nb pressure tubes have a high risk for the formation of blisters during their operation in pressurized heavy water reactors, there has been a strong incentive to develop a method for the non-destructive detection of blisters grown on the tube surfaces. However, because there is little mismatch in acoustic impedance between the hydride blisters and zirconium matrix, it is not easy to distinguish the boundary between the blister and zirconium matrix with conventional ultrasonic methods. This study has focused on the development of a special ultrasonic method, so called ultrasonic velocity ratio method for a reliable detection of blisters formed on Zr-2.5Nb pressure tubes. Hydride blisters were grown on the outer surface of the Zr-2.5Nb pressure tube using a cold finger attached to a steady state thermal diffusion equipment. To maximize a difference in the ultrasonic velocity in hydride blisters and the zirconium matrix, the ultrasonic velocity ratio of longitudinal wave to shear wave, $V_L/V_S$, has been determined based on the flight time of the longitudinal echo and reflected shear echo from the outer surface of the tubes. The feasibility of the ultrasonic velocity ratio method is confirmed by comparing the contour plots reproduced by this method with those of the blisters grown on the Zr-2.5Nb pressure tubes.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.3
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• pp.233-243
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• 2017

This paper proposes a structure of direct-printed flexible tactile-sensor. These flexible tactile sensors are based on pressure-sensing materials that allow pressure to be measured according to resistance change that in turn results from changes in material size because of compressive force. The sensing material consists of a mixture of multi walled carbon nanotubes (MWCNTs) and TangoPlus, which gives it flexibility and elasticity. The tactile sensors used in this study were designed in the form of array structures composed of many lines so that single pressure points can be measured. To evaluate the performance of the flexible tactile sensor, we used specially designed signal-processing electronics and tactile sensors to experimentally verify the sensors' linearity. To test object grasp, tactile sensors were attached to the surface of the fingers of grippers with three degrees of freedom to measure the pressure changes that occur during object grasp. The results of these experiments indicate that the flexible tactile sensor-based robotic gripper can grasp objects and hold them in a stable manner.

• Journal of the Korea Society of Computer and Information
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• v.20 no.10
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• pp.15-21
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• 2015

In this paper, we propose a stable automatic signature verification algorithm applicable to various smart devices. The proposed algorithm uses real and forgery data all together, which can improve the verification rate dramatically. As a tool for signature acquisition in a smart device, two applications, one using touch with a finger and the other using a pressure-sensing-stylus pen, are developed. The verification core is based on SVM and some modifications are made to include the characteristics of signatures. As shown in experimental results, the minimum error rate was 1.84% in the SVM based method, which can easily defeat 4.38% error rate with the previous parametric approach. Even more, 2.43% error rate was achieved with the features excluding pressure-related features, better than the previous approach including pressure-related features and only about 0.6% more error than the best result, which means that the proposed algorithm can be applied to a smart device with or without pressure-sensing-stylus pens and used for security purposes.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2004.11a
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• pp.57-57
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• 2004

• The Korean Journal of Emergency Medical Services
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• v.23 no.3
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• pp.67-81
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• 2019

Purpose: The purpose of this study was to compare the difference in compression quality and fatigue levels in a rescuer for three different hand techniques used in cardiopulmonary resuscitation (CPR). Methods: The participants were paramedic students at the basic life support provider level. The hands-only CPR was performed for 10 minutes for each of the three hand techniques without disruption, and the quality of chest compressions and fatigue levels were analyzed. Results: There was no difference between the sexes in the chest compression quality and the physiologic parameters before and after compression. Among the quality indexes of chest compression with each of the techniques performed for 10 minutes, the mean depth (p<.01) and mean accuracy (p=.000) of the compression were found to be higher in the five finger fulcrum technique, while the mean compression rate and relaxation accuracy showed no significant differences. Regarding fatigue levels, the five finger fulcrum technique caused lesser subjective fatigue as compared to other techniques (p<.05), although the heart rate and blood pressure revealed no difference. Conclusion: The five finger fulcrum technique was found to be better than the other techniques in terms of chest compression quality and subjective levels of fatigue, indicating that it should be used in CPR education.

• Physical Therapy Rehabilitation Science
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• v.4 no.2
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• pp.61-65
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• 2015

Objective: The aim of this study was to objectively evaluate sensory disturbance in cervical spondylosis using grip force and investigate the relationship between the grip force and upper extremity function. Design: Cross-sectional study. Methods: Eleven cervical spondylosis patients with paresthesia conducted grip and lift tasks using a precision grip with the tips of the thumb and index finger on either side. The sum of the grip force used during the first four seconds was calculated and defined as the total grip force. The cutaneous pressure threshold of the fingers, the pinch power, the grip power and three subtests of the Simple Test for Evaluating Hand Function (STEF) were also assessed. Correlations between the total grip force and cutaneous pressure threshold, pinch power, grip power, and STEF subtest times were evaluated. Results: We found that the total grip force correlated with the cutaneous pressure threshold (p<0.05). Moreover, the total grip force of the dominant thumb correlated with the results of the three STEF subtests (p<0.05). There were no significant correlations between the total grip force and pinch/grip powers. Conclusions: We found that the total grip force correlated with cutaneous pressure threshold and upper extremity function. The results suggest that the total grip force could serve as an objective index for evaluating paresthesia in cervical spondylosis patients, and that the impaired ability of the upper extremity function is related to grip force coordination.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.1
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• pp.81-86
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• 2015

This paper presents a disposable passive suction pump that uses the restoring force of an elastomeric chamber for liquid transportation in a microfluidic system. The proposed suction pump can be operated by finger pressure without any peripheral equipment. To adjust the generated suction pressure, five different displacements of the suction chamber ceiling, two different chamber shapes, and five different elastic moduli of the elastomer were considered. For a cylindrical chamber with a 5 mm height and 5 mm radius, the generated suction pressure and flow rate increased almost linearly up to about 31 kPa and $160.8{\mu}L/min$, respectively, depending on the chamber deformation. A maximum suction pressure of $42.9{\pm}0.7kPa$ was obtained for a hemispherical chamber with a 2.1 mm height and 5 mm radius.