• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.9-12
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• 2008

PSC-I girder is widely used in designing bridge. Currently partial advanced country have constructed bridge with high strength concrete, while in-country rather less concrete strength(40MPa) has been used to build bridge girder. So, this paper presents characteristics and behavior of member casted by high strength concrete to apply practically. For this aim, 4 girders were fabricated to investigate performance and structural behavior. Prior to test, structural analysis was performed with common program. Steel gages and concrete gage were filled up to measure longitudinal and vertical strain of reinforcement and concrete. Linear Variable Differential Transducer and concrete surface gage were also set to measure deflection and strain of concrete. Load-deflection relation and crack mode were analyzed at transfer and test and compared with the structural analysis

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.477-484
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• 1997

This paper describes the build-up force measuring system of 9.9 MN capacity which consists of nine force transducers of each having 1.1 MN capacity. We have specially designed a force transducer for a build-up force measuring system to reduce the uncertainty of a build-up system and to accomodate the new test procedure for a build-up system. It reveals that the relative uncertainty of the force measuring system is less than 1.5*10$^{-4}$ in the ran9e of 1-4.5 MN irrespective of loading direction. The force measuring system may be used to calibrate a 10 MN force standard machine to be used as a large force standard in Korea.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.16-21
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• 1999

Recently, the rheology on the fluidity of materials has been progressed remarkably. Viscosity measurement for precision-accuracy has needed very important to measure the rheological properties of materials in the field of chemistry-fiber, paint, printing-ink, plastics, rubber, foodstuff-industry, etc. And many methods of measurement have been developed lately. So in this experimental study, small capacity torque transducer with type of strain gage, different method against other existing viscometers, measured viscosity about a liquid that has flowing characteristics of newtonian liquid. Using the assumed computational equation of viscosity, it has same value of viscosity in each different radius of rotating cylinder. In the result, this equipment will be used in the viscosity measurement of a liquid taking flowing characteristics of newtonian liquid.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1476-1478
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• 1996

This paper describes the recent development of a thin-film pressure transducer with Cu-Ni films as strain gages. The construction details and the output characteristics are presented. In order to improve the sensitivity and the temperature compensation, two circumferential gages are placed in the central region of the diaphragm, and two radial gages are placed near the edge. The output sensitivity obtained is 2.1mV/V and the maximum non-linearity and hysteresis is less than 2%FS.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.3
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• pp.173-180
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• 2001

In the past few years, the nondestructive inspection technology has greatly developed due to the increased necessity to gain a complete understanding of the bridge behavior. Especially, the deformations of bridges contain a lot of informations about its health state. By measuring these deformations it is possible to analyze the loading and aging behavior of the structure. However, the current, methods (such as LVDT, dial gage, optical displacement transducer, etc) are often of changeable application on site and have the limitations of installation. In this paper, the classical beam theory was reviewed and the deflections of structure are estimated using measured strain which is easy to acquire. The applicability of this algorithm is verified by laboratory(simple reinforced concrete beam) and field test. By this test, we proposed correction factor to estimate deflection of reinforced concrete beam after cracking, and analyze about the generation of correction factor. Also fiber optic sensors as well as resistive strain gages were installed in the concrete beams to establish the applicability of fiber optic sensors in the field of civil engineering.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.1
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• pp.63-68
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• 2004

Recently ER fluids are put to practical use in fluid power industry field. As only with electrical signal change to the valve in which ER fluid flowing, ER fluid flow is controlled, so devepment of simple ER valves have been tried. In this case a technical problem is to check the pressure drop caused from flow rate change in valves because the pressure drop is very small. In this study ER valves are designed and manufactured, and small pressure drop induced from flow rate change is checked by pressure transducer which is made with appling strain gage. The ER valves and pressure drop check method are considered to be applied to the fluid power industry.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.31-40
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• 2009

As the measurement of strain-gage type cone penetrometer is influenced by the temperature change during penetration, the temperature is a factor producing an error of the cone tip resistance. In this study, the 0.5 mm diameter temperature transducer and 7 mm diameter micro cone penetrometer are manufactured by using FBG sensors to evaluate the effect of temperature on the cone tip resistance. Design concepts include the cone configuration, sensor installation and the temperature compensation process. The test shows that the tip resistance measured by strain gauge is affected by the temperature change. The error of the tip resistance increases with an increase in temperature change, while the temperature effect on the tip resistance of FBG cone is effectively compensated by using FBG temperature transducer. Temperature compensated tip resistance of the strain gauge cone shows the good matched profile with FBG cone which performs real-time temperature compensation during penetration. This study demonstrates that the temperature compensation by using FBG sensor is an effective method to produce the more reliable cone tip resistance.

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.341-354
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• 2003

The purpose of this study was to develop the uniaxial force plate system which is measured by the vertical force. The VGRF(vertical ground reaction force) 1.0 was composed of 2 bath digital scales, 2 indicaters, and analyzing software. This system was newly renovated to VGRF 2,0 which are 2 industrial digital scales, 2 adjustable indicators, and enforced analyzing software. Changes of the new system were as follows. First, the height of the plate was 75% lower than before. Second, sensing ability of the load cell was changed from 90 - 0.05kg to 300 - 0.1kg. Third, the speed of data processing was changed from 17 per second to 60 per second. Fourth, analyzing software was enforced to develop and calculate the data. For the test of the system, two different types(bare foot, high-heeled shoes) gait was adopted. highly skilled female walker(23yrs, height 165cm, body mass 46.8kg) participated for the experimental study. During the dynamic performance(gait analysis), the data of each load cell were very similar to the previous studies. Specifically, bare foot walking had less vertical force than high-heeled shoes. Consequently, VGRF 2.0 can sense the general dynamic movements as well as static load conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.4
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• pp.215-225
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• 2001

Stress waves monitored on the surface of structures under various loading conditions can provide useful information on the structural health status. In this paper, stress waves are measured by several sensors when a steel beam is impacted by a ball drop. The sensors used include the piezo-electric film Sensor, the electrical strain gage, and the ultrasonic transducer, and special attention is given to the pieza film sensor. The wavelet transform is used for the time-frequency analysis of dispersive waves propagating in the beam. The velocities of the wave produced in the team due to the lateral impact is found to be frequency-dependent and identified as the flexural wave velocity based on the comparisons with the Timoshenko beam theory. A linear impact site identification method is developed using the flexural wave, and the impact sites of the beam can be accurately estimated by the piezo film sensors. It is found that the piezo film sensor is appropriate for sensing stress waves due to impact and for locating impact sites in the beam.

• Journal of Biosystems Engineering
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• v.26 no.5
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• pp.461-468
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• 2001

Impact between fruits and other materials is a major cause of product damage in harvesting and handling systems. The oriental pears are more susceptible to bruising than other fruits such as European pears and apples, and are required more careful handling. The interest in the handling of the pears for the processing systems has raised the question of the allowable drop height to which pears can be dropped without causing objectionable damage. Drop tests on pears were conducted using an impact device developed by authors to estimate the allowable drop height without bruising. The impact device was constructed to hold in a selected orientation and to release a fruit by vacuum for dropping on to a force transducer. The drop height was adjustable for zero to 60 cm to achieve the desired distance between the bottom of the fruits and the top of the impact force transducer. The transducer was secured to 150 kg$\sub$f/ concrete block. The transducer signal was sampled every 0.17 ms with a strain gage measurement board in the micro computer where it was digitaly stored for later analysis. The selected sample fruit was Niitaka cultivar of pears which is one of the most promising fruit for export in Korea. The pears were harvested during the 1998 harvest season from an orchard in Daejeon. The sample fruit was selected from two groups which were stored for 3 months and 5 months respectively by the method of current commercial practice. The pears were allowed to stabilize at environmental condition(18$^{\circ}C$, 65% rh) of the experimental room. One hundred fifty six pears were tested from the heights of 5, 7.5. 10 and 12.5 cm while measurement were made of impact peak force, contact time, time to peak force, dwell time, pear diameter and mass. The bioyield strength and modulus of elasticity were measured using UTM immediately after each drop test. The allowable drop height was estimated on the base of bioyield strength of the pears in two ways. One was assumed the peak force during impact test increasing linearly with time, and the other was based on the actual drop test results. The computer program was developed for measuring the impact characteristics of the pears and analyzing the data obtained in the study. The peak force increased while contact times decreased with increasing drop height and contact times of the sample from the hard tissue group. The allowable drop height increased with increasing bioyield strength and contact times, and also varied with Poisson\`s ratio, mass and equilibrium radius of the pears. The allowable drop height calculated by a theoretical method was in the range from 1 to 4 cm, meanwhile, the estimated drop height considering the result of the impact test was in the range from 1 to 6 cm. Since the physical properties of fruits affected significantly the allowable drop height, the physical properties of the fruits should be considered when estimating the allowable drop height.