• Title/Summary/Keyword: Pressure rate

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Numerical Analysis for Evaluation of Ejection Capacity Relationship of Safety Valves in Pressure Regulating Station(I) - Flow Analysis and Mass Flow Rate Verification of Pressure Regulator - (정압기지내의 안전밸브 분출용량 관계식 검증을 위한 유동해석(I) - 정압기 유동 해석 및 질량 유량 검증 -)

  • Gwon, Hyuk-Rok;Roh, Kyung-Chul;Kim, Young-Seop;Lee, Seong-Hyuk
    • Journal of the Korean Institute of Gas
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    • v.12 no.2
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    • pp.99-104
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    • 2008
  • Gas pressure regulators in pressure regulating station reduce high-pressure gas in a process line to a lower. Gas pressure regulators are not flow control devices, they are used to control delivery pressure only. For the safety of pressure regulating station, it is essential to study flow regime and characteristics of a safety valves that is connected to a pressure regulator. For this, it is necessary to understand flow characteristics and the flow rate of upstream component part such as gas pressure regulators in regulating station. In the present study, numerical analysis of flow characteristics and the mass flow rate of a pressure regulator is conducted under the several inlet, outlet conditions and open rates. Then, the numerical result of the mass flow rate is verified with experimental equation from manufacture of pressure regulator. Consequently, the numerical result is comparatively good agreement with values from experimental equation.

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Study on the Injection Characteristics using Injection Rate in a Direct-injection Gasoline Injector with Multi-hole (분사율을 이용한 직접 분사식 다공 가솔린 인젝터의 분사특성 연구)

  • Park, Jeonghyun;Shin, Dalho;Park, Su Han
    • Journal of ILASS-Korea
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    • v.21 no.1
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    • pp.20-28
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    • 2016
  • This paper presents an experimental study on the GDI injector with Bosch method. The injection characteristics, such as the injection quantity, the injection rate, the maximum velocity of the nozzle exit and the injection delay were studied through the change of the injection pressure, the tube pressure and energizing duration in injection rate measurement device using nheptane. The injection quantity is increased by increasing injection pressure, decreasing tube pressure or increasing energizing duration. As the difference of the injection quantity changed, the shape of injection rate was moved with a constant form. The maximum velocity of the nozzle exit showed a tendency to increase as the injection pressure is increased. However, tube pressure did not affect. Overall, it was confirmed that the closing delay is longer than the opening delay in all conditions. As the injection pressure increased, the result has a tendency to decrease the closing delay, it did not affect the opening delay. Reduction of the closing delay showed the reduction of the injection duration. the tube pressure and energizing duration did not affect the injection delay (opening delay, closing delay).

Effects of subtraction meditation on perceived stress, self-efficacy, systolic pressure, diastolic pressure, and pulse rate in paramedic students (마음수련명상 프로그램이 응급구조학과 학생의 지각된 스트레스, 자기효능감, 혈압, 및 맥박수에 미치는 효과)

  • Lee, In-Soo;Choi, Eun-Sook
    • The Korean Journal of Emergency Medical Services
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    • v.21 no.2
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    • pp.89-102
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    • 2017
  • Purpose: The purpose of the study was to investigate the effects of subtraction meditation on perceived stress, self-efficacy, blood pressure, and pulse rate in paramedic students. Methods: A quasi-experimental study with non-equivalent comparison groups using pre and post-test design was performed. The experimental group consisted of 27 participants who attended the meditation program, and the control group consisted of 26 non-participants of the program. The data were analyzed using SPSS/WIN 24.0. Results: There were a statistically significant differences between the experimental group and the control group in perceived stress(t=2.301, p=.026), systolic pressure(F=18.531, p=.000), diastolic pressure(F=9.745, p=.003), and pulse rate(F=33.869, p=.000) between pretest and posttest results. Conclusion: The subtraction meditation program can help reduce perceived stress, systolic pressure, diastolic pressure, and pulse rate.

Interrelation of the Diamond Disk and pad PCR in the CMP Process (CMP 공정에서 Diamond Disk와 Pad PCR 상관관계 연구)

  • Yun, Young-Eun;No, Yong-Han;Yoon, Bo-Earn;Bae, Sung-Hun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.359-361
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    • 2006
  • As circuits become increasingly complex and devices sizes shrinks, the demands placed on global planarization of higher level. Chemical Mechanical Polishing (CMP) is an indispensable manufacturing process used to achieve global planarity. In the CMP process, Diamond Disk (DD) plays an important role in the maintenance of removal rate. According to studies, the cause of removal rate decrease in the early or end stage of diamond disk lifetime comes from pad surface change. We also presented pad cutting rate (PCR) as a useful cutting ability index of DD and studied PCR trend about variable parameters that including size, hardness, shape of DD and RPM, pressure of conditioner It has been shown that PCR control ability of pressure and shape is superior to RPM and size. High pressure leads to a decrease of cell open ratio of pad surface because polyurethane of pad is destroyed by pressure. So low pressure high RPM condition is a proper removal rate sustain. By examining correlations between RPM and pressure of conditioner, it has been shown that PCR safe zoneto satisfy proper removal rate has the range 0.06mm/hr to 0.12mm/hr.

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Unsteady Vaporization of Burning Droplet at High Pressure Environments With Linear Acoustic Mode (강한 음향장에 구속된 고압 액적의 연소)

  • Kim, Sung-Yup;Shin, Hyun-Ho;Yoon, Woong-Sup
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1122-1127
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    • 2004
  • an isolated droplet combustion exposed to pressure perturbations in stagnant gaseous environment is numerically conducted. Governing equations are solved for flow parameters at gas and liquid phases separately and thermodynamic parameters at the interfacial boundary are matched for problem closure. For high-pressure effects, vapor-liquid interfacial thermodynamics is rigorously treated. A series of parametric calculations in terms of mean pressure level and wave frequencies are carried out employing a n-pentane droplet in stagnant gaseous air. Results show that the operating pressure and driving frequency have an important role in determining the amplitude and phase lag of a combustion response. Mass evaporation rate responding to pressure waves is amplified with increase in pressure due to substantial reduction in latent heat of vaporization. Phase difference between pressure and evaporation rate decreases due to the reduced thermal inertia at high pressure. In addition to this, augmentation of perturbation frequency also enhances amplification of vaporization rate because the time period for the pressure oscillation is much smaller than the liquid thermal inertia time. The phase of evaporation rate shifts backward due to the elevated thermal inertia at high acoustic frequency.

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The Effect of Rotation of Discharge Hole on the Discharge Coefficient and Pressure Coefficient (송출공의 회전이 송출계수와 압력계수에 미치는 영향)

  • Ha, Kyoung-Pyo;Ku, Nam-Hee;Kauh, S.Ken
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.7
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    • pp.948-955
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    • 2003
  • Pressure coefficient in rotating discharge hole was measured to gain insight into the influence of rotation to the discharge characteristics of rotating discharge hole. Pressure measurements were done by the telemetry system that had been developed by the authors. The telemetry system measures static pressure using piezoresistive pressure sensors. Pressure coefficients in rotating discharge hole were measured in longitudinal direction and circumferential direction with various rotating speed and 3 pressure ratios. From the results, the pressure coefficient, and therefore the discharge coefficient, is known to decrease with the increase of Ro number owing to the increase of flow approaching angle to the discharge hole inlet. However, there exists critical Ro number where the decrease rate of discharge coefficient with the increase of Ro number changes abruptly; flow separation occurs from the discharge hole exit at this critical Ro number. Critical Ro number increases with the increase of length-to-diameter ratio, but the increase is small where the length-to-diameter ratio is higher than 3. The decrease rate of discharge coefficient with the increase of Ro number depends on the pressure recovery at the discharge hole, and the rate is different from each length-to-diameter ratio; it has tendency that the short discharge hole shows higher decrease rate of discharge coefficient.

ANALYSIS OF THE SUITABLE INJECTION PRESSURE FOR DIESEL INJECTION WITH HIGH PRESSURE

  • JEONG D. Y.;LEE J. T.
    • International Journal of Automotive Technology
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    • v.6 no.2
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    • pp.87-93
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    • 2005
  • Spray patterns were visualized using the shadowgraph method, and the droplet size and velocity were measured using PDPA for high-pressure injections up to 2,600 bars. The spray pattern and spray characteristics, such as penetration, spray width, spray angle, droplet size, injection duration, and droplet velocity, were investigated to determine the suitable injection pressure. Spray penetration, width, angle, and velocity increased continuously up to 2,600 bars with the injection pressure in a high-pressure region. The rate of improvement of the above spray characteristics, however, declined rapidly, when the injection pressure reached 2,000 bars. The injection duration and droplet size generally decreased with the increase in the injection pressure, while the rate of improvement decreased abruptly after 2,000 bars. Consequently, the improvement rate of the spray characteristics became blunt at over 2,000 bars. This means that the suitable injection pressure is around 2,000 bars.

Effects of Pressure Tapping on flow Rate Characteristics of Triangular Separate Bar Differential Pressure flow Meter (삼각 분리 막대형 차압 유량계의 압력탭이 유량 특성에 미치는 영향)

  • Lee, Choong-Hoon;Park, Dong-Sun
    • 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.

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A Study for Changes of Blood Pressure and Heart Rate by Acupressure to Acupoints in Rat Model of Hemorrhagic Shock (출혈성 쇼크 흰쥐 모델에서 경혈 지압이 혈압과 심박수 변화에 미치는 영향)

  • Yang, Seung-Bum;Byun, Sin-Kyu;Kim, Jae-Hyo
    • Korean Journal of Acupuncture
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    • v.33 no.2
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    • pp.58-66
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    • 2016
  • Objectives : In order to find a possible non-invasive manipulation tool for maintenance of the cardiovascular functions in hemorrhagic shock, this study was aimed at evaluating effects of acupoints acupressure on the changes in blood pressure and heart rate from an animal model of hemorrhagic shock. Methods : In adult Sprague-Dawley rats, hemorrhagic shock was induced by a withdrawal of arterial blood from the femoral artery with volume of 0.8 ml per 100 g of body weight using peristaltic syringe pump. We applied the acupressure with a pressure oscillator to tail as a control and 2 different acupoints of sobu(HT8), youngchun(KI1) under 3 different conditions : 1) normal arterial blood pressure without bleeding, 2) at the beginning of bleeding, and finally 3) hemorrhagic shock. Results : Under normal arterial blood pressure without hemorrhage, there was a significant increase in systolic and diastolic blood pressures by the acupressure to the tail, HT8 and especially KI1 for 30 sec compared with before acupressure. Under hemorrhagic shock condition, the tail acupressure had minimal changes in cardiovascular parameters. Either the HT8 or KI1 acupressure resulted in a significant increase in arterial pressure but did not heart rate. At the beginning of bleeding, tail acupressure failed to change the reduction of arterial pressure and heart rate. However, there was a significant increase in blood pressure and heart rate following either the HT8 or especially KI1 acupressure. Conclusions : HT8 and KI1 acupressure affected cardiovascular signs but tail acupressure did not in rat model of hemorrhagic shock. These experimental data suggest that a acupressure with a pressure oscillator to HT8 or KI1 can be one of alternative emergency manipulations to ameliorate compromised cardiovascular functions under hemorrhagic shock condition.

A Study on the Strategy to Maintain Optimal Flow-rate and Pressure of the Piping System for Individual Heating (개별 난방방식에서의 배관 내 절정 유량 및 압력유지에 관한 연구)

  • Hong Seok-Jin;Ryu Seong-Ryong;Seok Ho-Tae;Yeo Myoung-Souk;Kim Kwang-Woo
    • Journal of the Korean housing association
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    • v.17 no.2
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    • pp.11-18
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    • 2006
  • For the more comfortable thermal environment in residential buildings, it was necessary for variable components like as automatic flow limiting valves and/or balancing valves in hydronic system. And, these components had an effect on flow-rate and pressure inside pipe. In this case, the incompatibility between the design for the heating system and the selection of equipment was the causes of several problems in heating pipe network. In this study, we peformed measurements and analyses of flow rate and pressure inside pipe for radiant floor heating in residential buildings through field surveys and experiments in order to find out the actual conditions and problems. On the basis of this, we suggested the approach for the optimal flow-rate and pressure maintaining inside pipe in individual heating system.