• Journal of ILASS-Korea
• /
• v.1 no.2
• /
• pp.50-56
• /
• 1996

In an fuel injection type gasoline engine, atomization of fuel droplet and mixture formation process are very important to understand engine combustion efficiency, and also has influence directly on the decision of engine performance and pollutant emission. In this study, perforated throttle valve instead of solid type throttle valve was developed and equipped to an SPI engine to promote secondary atomization and good droplet-air mixture formation. From the engine performance lest. it was verified that the case of perforated valve kas more advantages in each experimental parameters such as in cylinder gas pressure, mass burnt ratio, fuel consumption rate, and pollutant emission characteristics than that of solid one equipped. No matter what the same perforated valve, there are some distinct results in engine performance characteristics according to the perforate ratio.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.32 no.1
• /
• pp.39-46
• /
• 2008

The loss coefficient of the butterfly valve which allows partial opening of the valve at closed position and is applicable to the small-sized pipe system with the diameter of 1 inch was measured for the variation of the valve disk blockage ratio. Two different types of the valve disk configuration to adjust the blockage ratio were considered. One was the solid type valve disk of which the diameter was changed into the smaller size rather than the pipe diameter, and the other was the perforate type valve disk on which some holes were perforated. The results from two types of valve disk were compared to identify their characteristics in the loss coefficient distributions. The loss coefficient and the controllable angle of the valve disk were decreased exponentially with the decrease of the blockage ratio. In addition, the perforate valve disk had the effect on the higher loss coefficient rather than the solid type valve disk.

• Journal of ILASS-Korea
• /
• v.1 no.1
• /
• pp.55-62
• /
• 1996

In a fuel injection engine, atomization of liquid fuel and mixture formation process has influenced(or affected) directly on the engine performance and pollutant emission. In this study, the characteristics of fuel spray and the behaviors of secondary atomization developed at the downstream of the valves were investigated using an image processing method. Solid and perforated valves are chosen in order to evaluate the valve performance in terns of air flow rate, valve opening angle and valve shape. Experimental results clearly indicate that the spray atomization quality can be improved by increasing the perforated rat io and the blockage rat io in the perforated valve, the characteristics of spray atomization is improved by using the perforated valve with high perforated rat io and blockage ratio.

• Journal of ILASS-Korea
• /
• v.1 no.3
• /
• pp.60-66
• /
• 1996

Finely atomized fuel droplet and good mixed mixture plays very important in improving combustion efficiency in an spark ignition engine. And combustion efficiency has influence directly on the engine power, fuel consumption rate and pollutant emission. In this study, perforated throttle valve which has relatively low value of PR has been developed and studied for the purpose of improving those aims. As a result of this study, it has been verified that the perforated throttle valve makes droplet more finely, and also proved that has a function of contributing to form good mixed mixture, especially in mixture preparation system of carburetor or SPI type spark ignition engine.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.11a
• /
• pp.379-383
• /
• 2000

This paper describes the design program of duct silencer. Duct silencer is used ventilating system. Variables in the program for predicting transmission loss are width of splitter, airway width, perforate plate, absorption material and frequency. Generally used expression for predicting transmission loss has something that don't think about frequency characteristic. Therefore we propose the new expression that considered frequency characteristic. In the 1/1 octave band center frequency, the expected weighting number(K) is fitted with absorption ratio and airway width. The fitted 2nd degree polynomial expression is based on the test data performed in YOUIL Industrial Corperation. This program's accuracy is about 90 percent.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.4
• /
• pp.275-281
• /
• 2014

This study has been analyzed the sound performance of the noise barriers with respect to the configuration of the front perforated panel geometries and the filled absorption materials. Noise barriers' acoustic performance should be required to meet 0.7 of NRC value at least. The global absorbing performance of the barriers have been investigated by changing the opening ratio of the front perforated panel and the absorbing characteristics of the absorbing material using two microphone method. Therefore, It it possible to obtain to increase acoustic performance of the specific frequency ranges by designing the perforate rates of the front panel and absorbing characteristics of the absorbing materials inside, as well. This study try to find out the possibilities of applying the absorbing noise barrier to railway usage.

• Journal of Navigation and Port Research
• /
• v.30 no.6 s.112
• /
• pp.439-446
• /
• 2006

In ship structures many of the structural plates have cutouts, for example, at inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has a cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed In general, actual ship structure adopted reinforcement of stiffener around the cutout in order to preventing from buckling so it need to examine a buckling and ultimate strength behaviour considering a cutout because In many ship yards used class rule for calculating buckling strength but it is difficult to evaluate perforate stiffened plate with random size. In the present paper, we investigated several kinds of perforated stiffened model from actual ship and then was performed finite element series analysis varying the cutout ratio, web height, thickness and type of cross-section using commercial FEA program(ANSYS) under compressive load.