• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.10
• /
• pp.1359-1367
• /
• 2000

In-situ particle monitors(ISPMs) are widely used for monitoring contaminant particles in vacuum-based semiconductor manufacturing equipment. In the present research, the performance of a Particle Measuring Systems(PMS) Vaculaz-2 ISPM at low pressures has been studied. We generated the uniform sized methylene blue particle beams using three identical aerodynamic lenses in the center of the vacuum line, and measured the detection efficiency of the ISPM. The effects of particle size, particle concentration, mass flow rate, system pressure, and arrangement of aerodynamic lenses on the detection efficiency of the ISPM were examined. Results show that the detection efficiency of the ISPM greatly depends on the mass flow rate, and the particle Stokes number. We also found that the optimum Stokes number ranges from 0.4 to 1.9 for the experimental conditions.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.23 no.5
• /
• pp.494-501
• /
• 2015

Nowadays, many people are trying to develop eco-friendly engines such as the electric motor and the air engine because the I.C. engine cause a lot of pollutants. Nevertheless of these effort, there are few evaluation and comparison of these engines to conventionally used I.C. engines. Because of this, it is difficult to determine that the eco-friendly engines are really energy saving engines. In this paper, the efficiency of the air engine is calculated. The air engine does not cause environmental pollution problem because it uses "Compressed air". Due to the air engine operated at a low temperature and spark-free condition, this engine can be used in extreme condition for safety. Despite the many advantages of the air engine, there are few analysis on the air engine because of an air engine is low energy density.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.472-475
• /
• 1997

It is well known that pneumatic motors convert fluid power into mechanical power with a low efficiency. The Value of the efficiency depends on several factors, of which the most important are ; type of motor, speed, supply pressure, sie and geometry of the motor. This paper presents an analytical and experimental study of the performance of he vane type pneumatic motors. This investigation deals with all the pneumatic motors. This investigation deals with all the pneumatic motors. This investigation deals with all the major aspects of the air flow through a vane type pneumatic motor and pints out which are the main causes of the low efficiency of the motor, and therefore indicates which changes in a motor design an lead to optimum performance.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.5
• /
• pp.819-827
• /
• 1987

The purpose of the present investigation is to examine the effect of water addition on combustion efficieny. In this research, fuel and additive water are injected into a burner in the form of vapors through separate needle valves, the flame temperature and concentrations of soot, CO and unburned hydrocarbons were measured in a premixed flame. The results are obtained to be: In the fuel lean region, the reduction rate of CO, soot and HC by water injection increases slightly, but there is no change in the combustion efficiency. On the other hand, in the fuel rich region, the reduction rate of CO, Soot and HC by water injection increases more than that of the fuel lean region. Accordingly, combustion efficiency increases.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.283-286
• /
• 2002

The mixing of fuel and oxidizer and each mass distribution of unlike split triplet(F-O-O-F) injector for liquid rocket which are known to affect the combustion efficiency significantly, has been investigated using PLLIF technique. Experiment is conducted to investigate the effect of mixture ratio(MiR), momentum ratio(MoR) and impinging angle on mixing efficiency. The mixing efficiency, which is introduced by Rupe, gives the global chracteristic of spray mixing. Experiment far comparison with triplet injector(F-O-F), which has same momentum ratio and impinging angle with split triplet injector is conducted.

• Transactions of the Korean hydrogen and new energy society
• /
• v.9 no.1
• /
• pp.1-7
• /
• 1998

Most of today's energy supply is obtained from fossil fuels. Despite of high energy density, higher store efficiency and long mileage, fossil fuels cause environmental pollution and their reserves are limited. In this study pure hydrogen gas and oxygen gas are burned without the emission of pollution. A gas turbine is used to obtain power. Water is injected into a combustor, which prevents overheating and recovers cooling heat. Excessively supplied water is recirculated. With variation of mass flow rate and equivalence ratio, the affection of water injection rate and the temperature of injected water on efficiency and power are experimented. Injected water gets cooling heat, is expanded from liquid to vapor and raises the thermal efficiency. It is enable to determine the rate of water injection, which makes the maximum power. The increase of temperature of water injection raises the efficiency of the system.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.2
• /
• pp.184-193
• /
• 2002

This study aims at the optimal design of the screw rotor and its performance analysis. The optimal design of the screw rotor's shape has been performed theoretically. Also, the performance analysis technique of an oil-injected screw air compressor is developed. The effect of internal leakage, heat exchange between air and oil, and flow resistance at suction and discharge ports are included in the performance analysis. Some numerical examples of the volumetric efficiency and adiabatic efficiency for sample rotors are demonstrated for various lobe combination, rotor wrap angles and L/D ratios.

• Journal of the Korean Society of Mechanical Technology
• /
• v.13 no.4
• /
• pp.157-164
• /
• 2011

Hybrid car can improve fuel efficiency using a power of motor that is generated during constant-speed or deceleration driving. The motor is located between engine and transmission. But, when voltage of main battery is low, fuel efficiency is low because the voltage can't run the motor. In this situation, this study observed fuel efficiency when using solar cell for assistance power. In order to verify a fuel consumption of hybrid car equipped solar cell for assistance power, the car was tested downtown driving. As hybrid car was equipped solar cell for assistance, fuel consumption was reduced 8.35 % at running air conditioner. And, at air conditioner doesn't work, fuel consumption was reduced 6.88 %. This point of view, CO2 is expected to reduce in similar proportion.

• Journal of the Semiconductor & Display Technology
• /
• v.17 no.4
• /
• pp.51-55
• /
• 2018

As the OLED industry develops, display equipment is becoming larger. As a result, the stage required for display equipment is getting bigger. This enlargement led to increase in OLED production and industrial development. However, due to the large scale of the stage, other problems due to overheating and overheating caused by heavy load on the linear motor, which is mainly used in the stage, must be solved. In this study, a linear motor equipped with a cooling channel is modeled and the three - dimensional heat conduction flow analysis for this model is simulated using Fluent to analyze the cooling efficiency and cooling efficiency according to the cooling water flow rate. As a result, the cooling channel was effective and the cooling effect and efficiency were the best when the flow rate was about 5 ~ 10 L./min. In addition, the cooling effect is increased when the flow rate is increased, but the efficiency is significantly lowered when the flow rate is more than the predetermined value.

• Journal of the Korean Society of Visualization
• /
• v.18 no.3
• /
• pp.90-95
• /
• 2020

The purpose of this study is to numerically evaluate the collection performance of an ultra-small Lapple cyclone separator for 1~10 ㎛ particles introduced at flow rate of 10 L/min. The numerical evaluation reveals that a static pressure drop occurs more dominantly inside of the cyclone separator than at the inlet and the vortex finder. Also a fluid flow in the cyclone separator is confirmed to have a helical structure heading upward in the center of cyclone separator and downward in the vicinity of wall. The investigation on dust collection efficiency of the Lapple cyclone separator shows that particles of 4~8 ㎛ diameters are collected at very lower efficiency than other sizes. Then, the cut-point diameter of the cyclone separator is 1.48 ㎛.