• Title/Summary/Keyword: Pressure

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An analysis of cavity pressure for various injection molding conditions (성형조건에 따른 캐비티의 내압분포 분석)

  • Kim, D.W.;Kim, S.Y.;Shin, K.S.;Kim, D.W.;Kim, K.Y.;Lyu, M.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.293-296
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    • 2008
  • Injection molding operation consists of filling, packing, and cooling phase. The highest pressure is involved during the packing phase among the operation phases. Cavity pressure depends upon velocity to pressure switchover time and magnitude of packing pressure. The cavity pressure is directly related to stress concentration in the cavity of mold. Thus the observation and control of cavity pressure is very important to prevent mold cracking. In this study, cavity pressures were observed for operational conditions using the commercial CAE software, Moldflow. Operational conditions were velocity to pressure switchover time and packing pressure. Cavity pressures were also measured directly during injection molding. Simulation and experimental results showed good agreement.

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The pulsating pressure in the intake and exhaust manifold of a single cylinder engine by the various of engine revolutions

  • Chung, Han-Shik;Choi, Seuk-Cheun;Jong, Hyo-Min;Lee, Chi-Woo;Kim, Chi-Won
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.1
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    • pp.75-82
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    • 2004
  • In this research, a computer analysis has been developed for predicting the Pipe pressure of the intake and exhaust manifold in a small single cylinder engine. To get the boundary conditions for a numerical analysis one dimensional and unsteady gas dynamic calculation is performed by using the MOC(Method Of Characteristics). The main numerical parameters are engine revolutions. to calculate the Pulsating flow which the intake and exhaust valves are working. The distributions of the exhaust pipe pressures were influenced strongly to the cylinder pressures and the shapes of exhaust pressure variation were similar to the Inside of cylinder pressure As the engine revolutions are increased. the intake pressure was lower than ambient pressure. The amplitude of exhaust pressure had increased and the phase of cylinder pressure $P_c$ is delayed and the amplitude of cylinder pressure were increased.

A Study on the Pressure Rising Considered Fluid Inertia in the Notch Area of Balanced Type Vane Pump (노치 영역에서 유체 관성을 고려한 압력 평형형 베인 펌프의 압력 상승에 관한 연구)

  • 조명래;한동철;문호지;박민호;배홍용
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.168-175
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    • 1996
  • This paper reports on theoretical study of the pressure overshoot in the delivery ports and pressure rising within balanced type vane pump. Pressure overshoot occur due to the accelerated fluid through the notch, so, result in pressure ripple, flow ripple, and noise. For calculating the pressure rising and fluctuations of pressure, we have modeled mathematically used continuity equation based on compressibility and momentum equation considered fluid inertia in the notch, and analyzed simultaneously. As a results of analysis, we have found oscillation of pressure and compression chamber pressure depend on the rotational speeds, bulk modulus of working fluid, notches, number of vane and camring. Using the model, notches have been shown to be important design factor in relaxing the rapid pressure rising and reducing the amplitudes of pressure overshoot.

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A Study on the Post-brand Attachment Pressure Reception Behavior of Consumers

  • LEE, Jaemin
    • Journal of Wellbeing Management and Applied Psychology
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    • v.2 no.2
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    • pp.13-19
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    • 2019
  • This study is about pressure-accepting behavior of consumers attached to brands. Previous studies of the situation focused on time pressure and scarcity pressure, focusing on scarcity. The results of the study are as follows. First, consumers attached to brands were found to be relatively blunt in time pressures. This indicates that brands of consumers are attached to do not buy on impulse because of time pressure. Second, consumers attached to brands were found to be relatively under social pressure. This indicates that consumers who are attached to the brand do not buy with social pressures such as quasi-family groups. Third, consumers attached to brands were found to be relatively sensitive to scarcity pressures. Thus, a quantity-limited marketing strategy is generally more effective for consumers with high marketing effectiveness but high brand attachment. Fourth, unlike the one presented, consumers attached to the brand were found to be relatively insensitive to place pressure.

Static Pressure Drop of Airflow in Packed-bed of Fruits and Vegetables (청과물 퇴적층에서의 공기유동 정압강하)

  • 김의웅;김병삼;남궁배;정진웅;김동철;금동혁
    • Journal of Biosystems Engineering
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    • v.21 no.1
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    • pp.44-51
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    • 1996
  • The purpose of this paper is to obtain the basic data for design of pressure cooling system. Static pressure drop, as a function of superficial velocity, was measured for different stacking methods and stacking heights of some fruits and vegetables. At given superficial velocity, sphericity and void fraction had a much greater influence on static pressure drop than average diameter of spherical fruits such as apple, peach, tomato and kiwi fruit. Among cylindrical vegetables such as cucumber, carrot, radish and chinese cabbage, cucumber showed different pattern of static pressure drop because of its bended shape, radish showed less static pressure drop than other vegetables because its large sizes of voids. When cucumber and spinach were stacked vertically and horizontally to air flow, a much greater static pressure drop was shown in vertical than in horizontal type, therefore static pressure drop was affected not only by void fraction but also by void shape. Also, in packed-beds of fruits and vegetables, static pressure drop could be estimated very well by Ramsins equation.

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Characteristics of wind loads on roof cladding and fixings

  • Ginger, J.D.
    • Wind and Structures
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    • v.4 no.1
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    • pp.73-84
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    • 2001
  • Analysis of pressures measured on the roof of the full-scale Texas Tech building and a 1/50 scale model of a typical house showed that the pressure fluctuations on cladding fastener and cladding-truss connection tributary areas have similar characteristics. The probability density functions of pressure fluctuations on these areas are negatively skewed from Gaussian, with pressure peak factors less than -5.5. The fluctuating pressure energy is mostly contained at full-scale frequencies of up to about 0.6 Hz. Pressure coefficients, $C_p$ and local pressure factors, $K_l$ given in the Australian wind load standard AS1170.2 are generally satisfactory, except for some small cladding fastener tributary areas near the edges.

Effects of changes in blood pressure during brain vascular surgery on intraoperative neuromonitoring

  • Lee, Kyuhyun;Kim, Jaekyung
    • International journal of advanced smart convergence
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    • v.9 no.3
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    • pp.71-77
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    • 2020
  • This study was conducted in order to determine how reductions in blood pressure during surgery affect intraoperative neuromonitoring. This retrospective study considered a total of 339 patients: 194 patients with normal neuromonitoring findings (57%), 145 (42%) with abnormal neuromonitoring findings, and 34 (10%) with postoperative neurological deficits. Comparisons between the three groups revealed that overall blood pressure during surgery, postoperative blood pressure, and the difference between the maximum and minimum blood pressure could affect the intraoperative neuromonitoring findings. While we indicate that a drop in blood pressure to below 70 mmHg could affect neuromonitoring results, differences in the dosage of anesthetic agents did not significantly affect reductions in blood pressure or neuromonitoring findings. The association of monitoring with blood pressure found in this study is expected to help future examiners. However, this study did not clarify the relationship between anesthesia and blood pressure and how it could affect intraoperative neuromonitoring. Therefore, further research on this part is thought to be necessary.

The Control System of a Robot Bed for Caring Pressure Ulcer

  • Kim, Jungae;Lee, Youngdae;Cho, Hyunkyung
    • International Journal of Advanced Culture Technology
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    • v.8 no.3
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    • pp.254-259
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    • 2020
  • The medical bed developed in this study is an electrically driven segmental keyboard. First describe the instrument of the segmental bed specially designed for pressure ulcer prevention, then the motor control system and pressure ulcer prevention operation of the bed. The main factor of pressure ulcer generation is displayed as body pressure x time, and when the keyboard falls, the body pressure becomes zero, and the pressure becomes higher than the threshold even if the body pressure is above the threshold, the pressure control algorithm has been developed. Therefore, using the proposed pressure control method, it has no particular ulcer occurred theoretically.

An Experimental studies Spray characteristic of Pintle type Nozzle on High Pressure Chamber (고온.고압용기에서의 핀틀노즐의 분무특성에 관한 실험적 연구)

  • 송규근;정재연;오은탁;류호성;안병규
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.67-73
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    • 2002
  • The characteristics of fuel spray influence on the engine performances such as power, fuel economy and emissions. therefore, the measurement of fuel spray characteristics is very important for the improvement of heat engine. The factor which controls the fuel spray is injection pressure, ambient pressure, engine speed et al.. In :his study, We measured spray angle, spray penetration and spray tip velocity considering injection pressure(10,14㎫), ambient pressure(3,4,5㎫), fuel pump speed(500,700,900rpm) in the high temperature and pressure chamber. Experimental results are summarized as follows: 1) Injection pressure influence on the characteristics of spray namely As Injection pressure Is increased, spray angle is decreased but spray penetration and spray tip velocity is increased. 2) Spray angle, spray penetration is increased by increasing the fuel pump speed. 3) Ambient pressure plays an important role in spray characteristics.

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The Analytical Study on the Pressure Ripples in a Positive Displacement Vane Pump (유압 베인 펌프의 압력 맥동에 관한 연구)

  • 김기동;조명래;한동철;최상현
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.225-231
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    • 1997
  • This paper reports on the theoretical study of the delivery pressure ripples of a positive displacement vane pump which is widely used for automobile power steering. Pressure ripples occur due to the flow tipples which induced cam ring profiles and reverse flow from the delivery ports. In this paper, the mathematical model for analyzing the pressure ripples has been presented, and set of the differential equationshave been solved using the Runge-Kutta method. As the results of analysis, instant ideal flow ripples, internal pressure, delivery pressure ripples, and delivery flow ripples have been presented. Internal pressure was related to delivery pressure variations, and amplitude of pressure tipples was increased with rotational speed and delivery pressure.

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