• Journal of Advanced Marine Engineering and Technology
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• v.21 no.3
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• pp.302-310
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• 1997

In this paper, we find a method to improve ignitability using methanol which is prospective as an alternative fuel. The constant volume combuster is divided into main chamber and sub-cham¬ber. These two chambers are linked by an adapter which is shaped like a cup. We also compare CDI to HIS that is revised in our laboratory for making a scrutiny into the effects of ignition char¬acteristics. Besides, we analyze a flame propagation process in the main and sub-chamber through taking pictures 10, 000 frames per second by high speed camera at the state being fabricated quartz glass aside main and sub-chamber.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.231-235
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• 2002

A theoretical and experimental study on the combustion process in a constant volume micro combustor is described. Unlike in a macro scale constant volume combustor, the heat loss to the wall plays a major role in flame propagation in a micro micro combustor. In order to analyze the effect of heat loss on combustion phenomena, pressure transition from ignition was measured. A number of cylindrical micro combustors with different diameter and depth were used for experiment to study the effect of length scales and shape factor. The diameter of combustor ranged from 7.5mm to 22.5 mm and the height of cylinder was from 1mm to 4mm. Initial pressure was also varied for the experiment. The diagnostic methods were severely limited due to the size of the apparatus and uncertainties of certain quantities to be measured in a small-scale environment. An analytical method to derive physical quantities that are essential for performance prediction from the pressure measurements is described.

• Proceedings of the KIEE Conference
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• 2001.07e
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• pp.62-64
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• 2001

This paper presents a forecasting method for production volume of each model manufacture d goods by using Back-Propagation technique of Neural Networks. As the learning constant and the momentum constant are respectively 0.65 and 0.94, the teaming number is the least, and the forecating accuracy is the highest. When the learning process is more than 1,000 times, the accurate forecating was possible regardless of kind of product.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.298-300
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• 2001

This paper presents a forecasting method for production volume of each model manufactured goods by using Back-Propagation technique of Neural Networks. As the learning constant and the momentum constant are respectively 0.65 and 0.94, the learning number is the least, and the forecating accuracy is the highest. When the learning process is more than 1,000 times, the accurate forecating was possible regardless of kind of product.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.100-102
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• 1998

This paper presents technique to control blower at constant air volume rate using V/F Control. Especially, this control method have not pressure sensors to measure because of using torque-speed relation based on the fan laws. Therefore, this technique is very simple and practical.

• Journal of the Korean Society of Visualization
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• v.9 no.1
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• pp.42-48
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• 2011

Six different size of torch-ignition device were applied in a constant volume combustion chamber for evaluating the effects of torch-ignition on combustion. The torch-ignition device was designed for six different volumes and same orifice size. The combustion pressures were measured to calculate the mass burn fraction and combustion enhancement rate. In addition, the flame propagations were visualized by shadowgraph method for the qualitative comparison. The result showed that the combustion pressure and mass burn fraction were increased when using the torch ignition device. And the combustion duration were decreased. The combustion enhancement rates of torch-ignition cases were improved in comparison with conventional spark ignition. Finally, the visualization results showed that the torch-ignition induced faster burn than conventional spark ignition due to the earlier transition to turbulent flame and larger flame surface, during the initial stage. Finally, the initial flame propagation was affected by torch-ignition volume.

• Korean Journal of Digital Imaging in Medicine
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• v.16 no.2
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• pp.1-7
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• 2014

This study is to increase the accuracy of the diagnosis of benign prostatic hyperplasia by presenting a method that can accurately measure the residual urine amount of the bladder by using an ultrasound image. Agar powder, Propanol and distilled water were used as materials for making a phantom. In order to measure the volume, a $10m{\ell}$ cylinder, syringe and beaker were used. The image was obtained by scanning phantoms produced into six shapes. Each constant value was obtained by using the expression designed to measure the residual urine amount of the bladder and was compared and analyzed. The measuring method of Bladder volume was presented and a constant value for each shape was obtained and five observers measured it five times. According to the results of clinical application, the errors of Ellipse-beanbag, Shield-shield were 11.0%, 18.2%, respectively. Constant values depending on the shape of each phantom were presented in order to accurately measure the volume of the bladder in measuring the amount of residual urine for the diagnosis of benign prostatic hyperplasia. The accuracy of the volume using this was verified statistically(p > 0.05). Therefore, it is considered to be useful in diagnosing benign prostatic hyperplasia by using the ultrasound imaging measuring method presented.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.1-4
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• 1999

The attenuation coefficients of SiC particle reinforced low-density polyethylene (LDPE) matrix composites were measured by pulse echo method and dynamic elastic measure method with varying the volume fraction of SiC particle ranged from 0% to 40% and the size of SiC particles ranged from 0.8$\mu$m to 48$\mu$m. The SiCp/LDPE composites were fabricated with the melt injection process and the fabricated composites showed almost full density above 99% up to 40vo1% SiCp reinforcements. The attenuation constant of LDPE measured by dynamic elastic constant had same result with that measured by pulse echo method, but the attenuation constant of SiCp/LDPE measured by dynamic elastic constant did not have same result with that measured by pulse echo method.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.1
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• pp.45-56
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• 2001

A constant volume combustion chamber is employed to investigate the initial flame kernel development and flame propagation of gasoline-air mixtures with various ignition systems, ignition energy and spark plug electrodes. To do this research, four ignition systems are designed and manufactured, and the ignition energy is controlled by varying the dwell time. Several kinds of spark plugs are also made to analyze the effects of electrodes on flame kernel development. The velocity of flame propagation is measured by the laser deflection method. The output laser beam from He-Ne laser is divided into three parallel beams by a beam splitter. The splitted beams pass through the combustion chamber. They are deflected when contacted with flame front, and the voltage signals from photodiodes change due to deflection. The results show that higher ignition energy raises the flame propagation speed especially under the fuel lean operation. The wider electrode gap, smaller electrode diameter and sharper electrode tip make the speed of the initial flame propagation faster. The speed of the initial flame propagation is affected by electrode material as well. Electrode material with lower melting temperature help the initial flame propagation.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.221-228
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• 1997

The main purpose of this paper is to determine the dynamic optimal shapes of simple beam-columns with the constant volume. The parabolic function is chosen as the variable equation for the depth of regular polygon cross-section. The ordinary differential equation including the effect of axial load is applied to calculate the natural frequencies. The Runge-Kutta and Regula-Falsi methods are used to integrate the differential equation and compute the frequencies, respectively. Then the dynamic optimal shape whose lowest natural frequency is highest is determined by reading the critical value of the frequency versus section ratio curve plotted by the frequency data. In the numerical examples, the simple beam-columns are analysed and the numerical results of this study are shown in tables and figures.