• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.61-64
• /
• 2008

The present study of these experiments are close examination of spray characteristics that are continuous liquid jet and modulated pressure pulse liquid jet. The experiments were conducted using water, over a range of cross-flow velocities from 42${\sim}$136 m/s, with injection frequencies of 35.7${\sim}$166.2 Hz. Between continuous cross-flow jet and pressure pulsed cross-flow jet for characteristics of penetration, breakup point, spray angle and macro spray shape are investigated experimentally. In cross-flow field, main parameter of liquid jet for breakup was cross-flow stream rather than pressure pulse frequency. As oscillation of the periodic pressure that could make liquid jet moved up and down, the mixing efficiency was increased. Also, a bulk of liquid jet puff was detected at upper field of liquid surface. So, this phenomenon has a good advantage of mixing spray from concentration of center area to outer area. Because of pressure pulsation frequency, an inclination of SMD for the structured layer was evanescent. Cross-sectional characteristics of SMD at downstream area were non-structured distributions. Then cross-sectional characteristics of SMD size were about same tendency over a range that is effect of spray mixing. The tendency of volume flux value for various frequency of pressure pulse was same distribution. And volume flux was decreased when the frequency of pressure pulse increase.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.04a
• /
• pp.317-321
• /
• 2007

PSP (Pressure Sensitive Paint) technique can measure continuous pressure field by analyzing the oxygen quantity using optical method. The surface pressure of down stream after the sonic jet that injected transversely into the supersonic freestream was measured by PSP technique. Moreover the effect of various rectangular shaped cavities in front of the jet was measured by PSP technique. A comparison of the PSP results with conventional pressure tap and CFD indicates good agreement. The result shows that the cavity affects the pressure distribution in the rear of the jet injection.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2020.06a
• /
• pp.111-112
• /
• 2020

As buildings in South Korea become more skyscrapers, the risk of fire is also emerging. Thus, regulations, regulations, and guidelines are being improved to prevent the spread of smoke in the event of a fire in high-rise buildings, but research on smoke flow and pressure distribution in vertical spaces is insufficient. Therefore, in this study, the temperature of each floor in the vertical space according to the size of the fire is measured through the miniature model experiment, and the pressure difference is calculated to establish the basic data for the improvement of the performance of domestic air supply facilities in the future. Thus, a scale model of one-sixth the size of the actual building was produced to measure the temperature, and the pressure difference was derived by substituting the value for the expression. The pressure difference varies depending on the size of the cause of the fire, and it is believed that the differential pressure and conditions of the building should be taken into account before calculating the supply volume for the analysis of the pressure difference according to the size of the cause of the fire in the event of fire.

• 한국연소학회:학술대회논문집
• /
• 2000.12a
• /
• pp.212-216
• /
• 2000

Combustion phenomenon in scale-downed combustor is investigated. As the combustor volume decreases surface to volume ratio increases. for increased surface to volume ratio means increased heat loss and this increased heat loss affects reaction in combustion chamber. Plastic mini combustor is made. Stoichiometricaly premixed Hydrogen I air gas is used as fuel. Initial chamber pressure and chamber size are varied and the effects are evaluated. Peak pressure decreases with the decrease in chamber height. As initial chamber pressure decreases peak pressure decreases. And this change is more important than scale down effect till the chamber height of 1mm. With this result and further information following the experiments design parameter for micro engine can be established.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.3
• /
• pp.183-188
• /
• 2006

This research is to know differentiation of CP(center of pressure) pattern among four pitching sort(straight ball, raise ball, change up ball, drop ball). Subject are three national or junior athletes. We use the one camera, Novel Win pressure measurement system. Conclusions are as follows : 1. When we throw the straight ball, CP of left foot is effective to end movement at middle of foot in body balance on arm angular motion and enhanced speed. 2. When we throw the raise ball, to change CP from middle to post is more effective in order to raise the ball. 3.In drop ball pitching, in order to fall down the ball in front of hitter, CP of left foot move from post foot to interior part of forefoot 4. In change up ball pitching, if CP of left foot move into forefoot, it is a cause of high ball and hitter can recognize the change up ball because of late arm rotation motion.

• 유체기계공업학회:학술대회논문집
• /
• 2006.08a
• /
• pp.565-568
• /
• 2006

This paper achieved dynamic characteristics with test to use solenoid valve for flight model that have present. Designed pressure control virtual system which PWM solenoid valve to use test result. Examination compared solenoid valve dynamic characteristics in atmosphere and cryogenic fluid and presented technique and valuation method that measured upstream and down stream pressure of solenoid valve, as well as, temperature, excitation voltage etc. These test results could confirm solenoid valve response time and maximum using frequency characteristic at use in atmosphere and cryogenic temperature and this derived design variables pressure control system from those bases.

• 한국전산유체공학회:학술대회논문집
• /
• 2005.04a
• /
• pp.228-233
• /
• 2005

Two-dimensional Stokes flows through a micro channel with a couple of symmetric vertical fins are investigated. At far up- and down-stream from the fins, the plane Poiseuille flow exists in the channel. The slip boundary conditions are applied to take account of the Knudsen number effects. For the analysis, the method of eigen function expansion and collocation method are employed. By the results, the streamline patterns and pressure distributions are shown and the force exerted on the fin and the excess pressure drop due to the fins are determined as functions of the length of the fin and Knudsen number. It may be conjectured that the force and the excess pressure drop are almost independent of the Knudsen number.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.667-669
• /
• 2014

Development of 3 cylinder turbo charger engine is increasing due to engine down-sizing, cost reduction and emission regulations. However, 3 cylinder engine makes higher Exhaust manifold gas pressure(P3) pulsation than 4 cylinder engine and it generate boosting air with high pulsation. The mechanical waste-gate turbocharger just controlled by the boosting air has higher movement because of this high pulsation boosting air. This causes high vibrations to wasted gate and accelerate wear of the linkage system. So we need to understand out of the exhaust gas pressure pulsation changed by turbocharger compressor pressure(P2) Pulsation. In this study, we discuss how to prevent to abnormal movement of the turbo actuator by stabilized P2 Pulsation.

• Progress in Superconductivity and Cryogenics
• /
• v.4 no.2
• /
• pp.63-67
• /
• 2002

In this study, the performance of the Stirling type orifice Pulse tube refrigerator (OPTR) with a linear compressor was investigated by experiment. The dynamic pressures at three points and a temperature at the cold heat exchanger are measured to explore the dependency of the orifice on the performance of the OPTR. The experimental results show that the opening of the orifice has significant effects on the no load temperature and cool down characteristics. The Pressure amplitude in Pulse tube decrease as the opening of the orifice increase, but the mass flow rate through the orifice and the electric input Power to the compressor increase. The results show that the operating frequency and charging Pressure does not affect on the no load temperature. The pressure amplitude in pulse tube decrease as the operating frequency increase or the charging Pressure decreased.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.11 no.1
• /
• pp.40-49
• /
• 2003

Dynamic characteristics of water hammer arresters installed in a building water supply system have been investigated numerically by utilizing a commercial code that employs the method of characteristics. Some preliminary results with those arrester models produced in this study agree well with the previously reported. Then, the arrester models have been incorporated into a water supply pipe system of a 59 $m^2$apartment unit constructed by a leading construction company, and their dynamic characteristics have been investigated, especially on the reduction in the water hammer pressure. It is found that the setting of the arresters in the pipe system, which is recommended by the company, may not be proper for reducing the pressure down below 1,082.0 kPa (10.0 kg$g_f$/$cm^2$) when quick-closure valves in the pipe system are closed within 30 ms at the static pressure of 542.6 kPa (4.5 kg$g_f$/$cm^2$). More arresters in the system may be required to meet pressure criteria stated on the related standards and codes.