• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.562-567
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• 2003

This paper presents the method of Rate of Loading(ROL) improvement for the Motor Operated Gate Valve operating in high differential pressure condition. The character of ROL and Stem Factor is analyzed. Static test and dynamic test were performed and acquired the diagnosis signal for the valve closing stroke. The result of this study is the modification of stem factor is very important factor for the ROL improvement. In order to obtain the same value of dynamic test thread friction coefficient stem and stem nut should be combined appropriately.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.6
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• pp.135-142
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• 2016

We proposed the new method to estimate the blood pressure with the differential value of the digital arterial pulse waveform and BP relation equation. To get the digital arterial pulse waveform, we use the arterial pulse waveform measurement system that has digital air-pressure sensor device and smart phone. The acquired digital arterial pulse waveforms are classified as hypertension group, normal group, and hypotension group, and we can derive the average differential value between the highest point and lowest point of a single waveform of individuals along with the group. In this study, we found the functional correlation between the blood pressure and differential value as a form of BP relation equation through the regression process on the average of differential value and blood pressure value from a tonometer. The Experimental results show the BP relation equation can give easy blood pressure estimation method with a high accuracy. Although this estimation method has over 66 % error rate and does not give the high level of the accuracy for the diastolic compares to the commercial tonometer, the estimation results for the systolic show the high accuracy that has less than 10 % error rate.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.205.2-205.2
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• 2011

Micro hydraulic turbines take a growing interest because of its small and simple structure as well as high possibility of applying to micro and small hydropower resources. The differential pressure exiting within the city water pipelines can be used efficiently to generate electricity like the energy generated through gravitational potential energy in dams. In order to reduce water pressure at the inlet of water cleaning centers, pressure reducing valves are used widely. Therefore, pressure energy is wasted. Instead of using the pressure reduction valve, a micro counter-rotating hydraulic turbine can be replaced to get energy caused by the large differential pressure found in the city water pipelines. In this study, in order to acquire design data of counter-rotating tubular type micro-turbine, output power, head, and efficiency characteristics due to the diffuser.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.591-593
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• 2006

The differential pressure method has been used in the level measurement of steam generator in nuclear power plant. Two sensing lines from a steam generator to a pressure transmitter are needed to measure the high pressure and low pressure. The fluid conditions in the sensing line require the uniform phase with no bubbles and the slope of sensing line should be installed with forward slope. The expansion of the bubble volume according to the upper pressure and the reverse slope of sensing lines explain how the level errors took place.

• Structural Engineering and Mechanics
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• v.13 no.3
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• pp.329-343
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• 2002

In this research, the dynamic stability of an orthotropic elastic conical shell, with elasticity moduli and density varying in the thickness direction, subject to a uniform external pressure which is a power function of time, has been studied. After giving the fundamental relations, the dynamic stability and compatibility equations of a nonhomogeneous elastic orthotropic conical shell, subject to a uniform external pressure, have been derived. Applying Galerkin's method, these equations have been transformed to a pair of time dependent differential equations with variable coefficients. These differential equations are solved using the method given by Sachenkov and Baktieva (1978). Thus, general formulas have been obtained for the dynamic and static critical external pressures and the pertinent wave numbers, critical time, critical pressure impulse and dynamic factor. Finally, carrying out some computations, the effects of the nonhomogeneity, the loading speed, the variation of the semi-vertex angle and the power of time in the external pressure expression on the critical parameters have been studied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1123-1126
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• 2003

In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-Valve are measured by varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. The pressure drop according to the strength of electric field by differential pressure gauge in the present ER-Valve was used. This test reviewed experiment for the special changes of ER fluids in the steady flow condition.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.83-89
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• 2011

A series of full-scale testing was conducted to examine the effect of stairwell pressurization on the pressure differential between the stairwell and the auxiliary room and between the auxiliary room and the residence. Also, flow velocity profiles at open doors were measured. The building tested was a condominium that had twenty floors above the ground and two floors underground. For pressurization of the stairs, a blower was used to supply air into the stairwell at one location underground. Thirteen different cases were tested, and test variables included the number of floors with open doors and the flow rate of the air supply. When the doors on the first floor were open, the pressure differential between the stairwell and the auxiliary room was distributed almost uniformly except for locations near the first floor. When the flow rate was in the range of 180~270 CMM and the doors of one floor were open, the flow velocity could satisfy the requirement of fire safety standards and the stairwell pressure was positive at all levels. However, the minimum pressure requirement (10 Pa) could not always be satisfied. When doors on two floors were open, the flow velocity requirement could be satisfied by increasing the flow rate, but it was found impractical to satisfy the minimum pressure requirement without causing excessive pressure differential in the area near the blower.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1680-1686
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• 2009

Flow characteristics of a differential pressure flow meters which have a shape of triangular separate bar (TSB) was investigated according to machining conditions in pressure tapping holes. Size of pressure tapping holes is machined with either 1.0 mm or 1.5 mm in diameter. Also, number of pressure tapping holes are drilled either 9 or 17. The mass flow rate of the TSB flow meters are calibrated with a laminar flow meter by connecting them in line. The mass flow rate in the TSB flow meters are plotted with a non-dimensional parameter H which includes the gas temperature, exhaust gas pressure and differential pressure at the flow meters, and atmospheric pressure. An empirical correlation between the mass flow rate at the TSB flow meter and the non-dimensional parameter H was obtained. The empirical correlation showed highly linear relationship between the mass flow rate and the non-dimensional parameter H. The hole size of the pressure tapping holes has a bigger effect on the flow rate than the number of the tapping holes.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.13 no.3
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• pp.9-15
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• 2017

In this study, set values of PICV(Pressure Independent Control Valve) were simulated according to the pressure distribution and velocity. The higher the set value and the open rate, as the lower the pressure in the neck. On the contrary, the lower the set value and open rate, as the higher the pressure in the neck. When the set value was small, the pressure was distributed sufficiently and confirmed that the pressure was generated by the VOF, confirming that it could generate a vapor pressure. When the set value 100 %, the lower corn open rate of the differential pressure was 46 % to 29 %, set value 100 % was 29 % to 19 %, and set value 6 % was 12 % to 6 % for the lower corn open rate percentile, it was limited to within 50 %. Thus, the results of this study on the correlation between open rate and differential pressure of the set value of the PICV will be beneficial to improve performance of flow control valves and contribute to their efficient operation used for a hydronic system.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.235-238
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• 2008

High-rise buildings with stack effect caused by the foreclosure, which significantly delayed the spread of a fire in effects of these stack effect driving force said. In this research on the stack effect of the lobby if the pressurization of the stairwell analysis of the pressure distribution of the CONTAMW. Overall, the pressurization of the lobby makes it stairwell amount of pressure(+) to the zone in pressure designed to prevent the spread of smoke control performance and found that, the way a normal state and sub-pressurization in the stairwell with stack effect of the turbulence Such as the formation of the upper flow, but, in the upper atmosphere with pressurization was formed by the underlying trend.