• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.3
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• pp.105-113
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• 2007

This study was conducted to analyze the effects of environmental factors such as soil moisture, light intensity, temperature and humidity on changes in cambial electrical resistance. To improve data quality, cambial electrical resistance was continuously measured at fixed points by using a data logger isolated from alternating current. The relationship between environmental factors and changes in cambial electrical resistance was also analyzed. The results are as follows: 1. Cambial electrical resistance is highly correlated to the temperature of the measured area(r=-0.934). Therefore, temperature compensation is needed to analyze the effects of other environmental factors on cambial electrical resistance changes. 2. If temperature is compensated for, the change of cambial electrical resistance is highly correlated to water vapor pressure(r=-0.836). 3. If temperature and humidity are compensated for, the change of cambial electrical resistance is highly correlated to intensity of light(r=-0.738). 4. Diurnal deviation of soil water potential is not more significantly related than the change of cambial electrical resistance. However, in the long-term, soil water potential and cambial electrical resistance are highly correlated(r=-0.831). This indicates that soil moisture significantly influences the long-term change of cambial electrical resistance.

• Journal of Environmental Health Sciences
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• v.22 no.1
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• pp.12-20
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• 1996

This study was carried out to investigate the change of average .specific resistance according to suspension concentration for study phenomena occurring during filtration period. As the results of this study, the following conclusions were obtained. The average specific resistance in 1% $CaCO_3$ suspension was showed power function(R=0.99), whereas in TOYO 5C and TOYO 5A paper were made little difference under high pressure. It represented from results that filtration theory in concord with cake filtration was no affected the average specific resistance of filter medium in cake filtration. In case of 0.1% $CaCO_3$ suspension filtration, the TOYO 5C was showed power function, whereas in TOYO 5A paper differently. In the present study, the $P_1$ value was calculated from the average specific resistance by filtration method. Therefore, $P_1$ value were $1.68\times 10^4Pa$, $4.05\times 10^3Pa$, and $3.15\times 10^3Pa$ in $5.3\times 10^4Pa$, $1.3\times 10^4Pa$, and $8.2\times 10^3Pa$, respectively. We concluded that propriety of new filtration theory was also proved.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.373-378
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• 2006

We present the design, fabrication, and characterization of a multi-chip microelectrofluidic bench, achieving both electrical and fluidic interconnections with a simple, low-loss and low-temperature electrofluidic interconnection method. We design 4-chip microelectrofluidic bench, having three electrical pads and two fluidic I/O ports. Each device chip, having three electrical interconnections and a pair of two fluidic I/O interconnections, can be assembled to the microelectofluidic bench with electrical and fluidic interconnections. In the fluidic and electrical characterization, we measure the average pressure drop of $13.6{\sim}125.4$ Pa/mm with the nonlinearity of 3.1 % for the flow-rates of $10{\sim}100{\mu}l/min$ in the fluidic line. The pressure drop per fluidic interconnection is measured as 0.19kPa. Experimentally, there are no significant differences in pressure drops between straight channels and elbow channels. The measured average electrical resistance is $0.26{\Omega}/mm$ in the electrical line. The electrical resistance per each electrical interconnection is measured as $0.64{\Omega}$. Mechanically, the maximum pressure, where the microelectrofluidic bench endures, reaches up to $115{\pm}11kPa$.

• Journal of Chest Surgery
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• v.23 no.1
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• pp.32-40
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• 1990

Surgical correction of congenital cardiac defects in infants and children with an elevated pulmonary arterial pressure or pulmonary vascular resistance carries a significant early postoperative mortality. And accurate assessments of cardiac output is critically important in these patients. From April 1988 through September 1989, serial measurements of cardiac index, ratio of pulmonary-systemic systolic pressure, ratio of pulmonary-systemic resistance, central venous pressure, left atrial pressure, and urine output during the first 48 hours after the cardiac operation were made in 30 congenital cardiac defects associated with pulmonary hypertension. Cardiac index showed significant increase only after 24 hour postoperatively and this low cardiac performance in the early postoperative period should be considered when postoperative management is being planned in the risky patients. There were no variables which showed any significant correlation with cardiac index. In 12 cases[40%], pulmonary hypertensive crisis developed during the 48 hours postoperatively, and they were treated with full sedation, hyperventilation with 100 % 0y and pulmonary vasodilator infusion. In all patient with preoperative pulmonary hypertension, surgical placement of a pulmonary artery catheter is desirable to allow prompt diagnosis of pulmonary hypertensive crisis and to monitor subsequent therapy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.737-740
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• 2001

This paper describes the fabrication and characteristics of CrN thin-film type pessure sensors, which the sensing elements were deposited on SUS. 630 diaphragm by DC reactive magnetron sputtering in an argon-nitride atmosphere(Ar-(10%)N$_2$). The optimized condition of CrN thin-film sensing elements was thickness range of 3500${\AA}$ and annealing condition(300$^{\circ}C$, 3 hr) in Ar-10 %N$_2$deposition atmosphere. Under optimum conditions, the CrN thin-films for strain gauges is obtained a high resistivity, $\rho$=1147.65 ${\mu}$$\Omega$cm, a low temperature coefficient of resistance, TCR=-186 ppm/$^{\circ}C$ and a high temporal stability with a good longitudinal, 11.17. The output sensitivity of fabricated CrN thin-film type pressure sensors is 2.36 mV/V, 4∼20 mA and the maximum non-linearity is 0.4 %FS and hysteresis is less than 0.2 %FS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.731-734
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• 2002

This paper describes on the fabrication and characteristics of a ceramic thin-film pressure sensor based on Ta-N strain gauges for harsh environment applications. The Ta-N thin-film strain gauges are sputter deposited onto a micromachined Si diaphragms with buried cavity for overpressure protectors. The proposed device takes advantages of the good mechanical properties of single crystalline Si as diaphragms fabricated by SDB and electrochemical etch-stop technology, and in order to extend the operating temperature range, it incorporates relatively the high resistance, stability and gauge factor of Ta-N thin-films. The fabricated pressure sensor presents a low temperature coefficient of resistance, high sensitivity, low non-linearity and excellent temperature stability. The sensitivity is $1.097{\sim}1.21mV/V{\cdot}kgf/cm^2$ in the temperature range of $25{\sim}200^{\circ}C$ and the maximum non-linearity is 0.43 %FS.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.71-81
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• 2008

A macroscopic finite element model is applied to investigate the effect of fire induced spalling on the response of reinforced concrete (RC) beams. Spalling is accounted for in the model through pore pressure calculations in concrete. The principles of mechanics and thermodynamics are applied to compute the temperature induced pore pressure in the concrete structures as a function of fire exposure time. The computed pore pressure is checked against the temperature dependent tensile strength of concrete to determine the extent of spalling. Using the model, case studies are conducted to investigate the influence of concrete permeability, fire scenario and axial restraint on the fire induced spalling and also on the response of RC beams. Results from the analysis indicate that the fire induced spalling, fire scenario, and axial restraint have significant influence on the fire response of RC beams. It is also shown that concrete permeability has substantial effect on the fire induced spalling and thus on the fire response of concrete beams. The fire resistance of high strength concrete beams can be lower that that of normal strength concrete beams due to fire induced spalling resulting from low permeability in high strength concrete.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.81-88
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• 1998

During an earthquake, there are three main components of excitation : horizontal excitation of the ground, vertical excitation of the pile due to superstructure feedback produced by vertical excitation of the ground, and the seawater excitation induced by the vertical ground shaking, that is, "the seaquake." These excitations could have effects on the soil plugs in open-ended pipe piles installed at offshore sites. In this study, seaquake excitation induced by the vertical ground shaking was simulated by pulsing the water pressure at the seabed. During a seaquake, due to induced excess porewater pressure and pressure gradients in the soil, the capacity of open-ended pipe piles installed in a simulated sea depth of greater than 220 m was reduced serevely and the soil plugging resistance was degraded by more than 80%. The soil plug was failed because of the upward seepage forces that developed in the soil plug due to excess pore water pressure produced in the bottom of the soil plug during the seaquake. The compressive capacity of an open-ended pile in a simulated sea depth of less than 220m was reduced only by about 10%, and the soil plug resistance was degraded by less than 5%.s than 5%.

• Journal of the Korean Institute of Gas
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• v.14 no.4
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• pp.45-50
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• 2010

The marine pipelines laid in deep waters were evaluated to verify the resistance on the plastic collapse to heavy ambient external pressure due to hydrostatic pressure. In this study, the plastic collapse behavior of the marine pipe subjected to hydrostatic pressure was evaluated with the ovality and ratio of diameter to thickness in FE analyses. A parametric study was shown that the internal pressure increased the plastic collapse depth by increasing of the resistance to the plastic collapse. It was also shown that the collapse depth of the pipeline having a local ovality was deeper than that of the pipeline having a global ovality. Finally, the plastic collapse depth decreased when either the ratio of diameter to thickness or the ovality increased.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.104-109
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• 2021

Tactile sensors and integrated circuits that detect external stimuli have been developed for use in various industries. Most tactile sensors have been developed using the MEMS(micro electro-mechanical systems) process in which metal electrodes and strain sensors are applied to a silicon substrate. However, tactile sensors made of highly brittle silicon lack flexibility and are prone to damage by external forces. Flexible tactile sensors based on polydimethylsiloxane and using a multi-walled carbon nano-tube mixture as a pressure-sensitive material are currently being developed as an alternative to overcome these limitations. In this study, a manufacturing process of pressure-sensitive materials with low initial electrical resistance is developed and applied to the fabrication of flexible tactile sensors. In addition, flexible tactile sensors are developed with pressure-sensitive materials dispensed on a substrate with flexible mechanical properties. Finally, a study is conducted on the change in electrical resistance of pressure-sensitive materials according to the modulus of elasticity of the substrate.