• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.6
• /
• pp.90-99
• /
• 2002

The main purpose of this study lies on the development of micro dilution tunnel based on the Sierra Dilution chamber model. As a primary examination, characteristics of flow and temperature distributions during the steady dilution process in dilution chamber are observed with numerical analysis. The penetration of dilution air through porous tube as well as wall temperature and temperature gradient inside porous tube are examined. The thermophoretic velocity in terms of temperature behavior inside porous tube are defined and examined. Based on the ratio of penetration and thermophoretic velocities, all part of porous tube are shown to be safe from the particulate depositions. However, The inlet portion of porous tube in addition to the portion of impinging of dilution air are marginally safe from the particulate depositions. Generally the safer design against particulate deposition is required in provision f3r steady dilution process and for transient process as well.

• Geomechanics and Engineering
• /
• v.21 no.3
• /
• pp.237-245
• /
• 2020

The process of evaporation from free water surface was simulated in a large scale environmental chamber under various controlled atmospheric conditions and also was modelled by a new mass transfer model. Six evaporation tests were conducted with increasing wind speed and air temperature in the environmental chamber, and hence the effect of atmosphere parameters on the evaporation process and the corresponding response of water were investigated. Furthermore, based on the experiment results, seven general types of mass transfer models were evaluated firstly, and then a new model consisted of wind speed function and air relative humidity function was proposed and validated. The results show that the free water evaporation is mainly affected by the atmospheric parameters and the evaporation rate increases with the increasing air temperature and wind speed. Both the air and soil temperatures are affected by the energy transformation during water evaporation. The new model can satisfactorily describe the evaporation process from free water surface under different atmospheric conditions.

• Journal of the Korean Society of Visualization
• /
• v.14 no.3
• /
• pp.32-37
• /
• 2016

In this study, the mixing process of two distinct flow is numerically investigated. Two flow with different physical properties (resin and hardener) are mixed through the opposing mixing jets. At a high pressure mixing process, the high speed flow is provided by two in-line nozzles. In the case of numerical modeling, Reynolds-Averaged Navier-Stokes Equations (RANS) is conducted to model the flow pattern inside the chamber. Additionally, SST k-omega turbulence model is selected to predict the kinetic energy of flow in impingement zone. The results show that mixing of two distinct flows would be efficient if the velocity of jet is high enough and nozzle diameter is a predominant parameter. Also, this velocity would create higher shear stress between two distinct flows which increases the mixing quality as well as strength of formed vortices. Eventually, the histogram of concentration fraction of resin is examined in order to show the quality of mixing and the range of concentration fractions in the output of chamber.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.12
• /
• pp.1240-1245
• /
• 2009

The throughput characteristics of the cluster tool with dual blade robot are analyzed. Using equipment's cycle time chart of the equipment, simple analytic form of the throughput is derived. Then, several important throughput characteristics are analyzed by the throughput formula. First, utilization of the process chamber and the robot are maximized by assigning the equipment to the process whose processing time is near the critical process time. Second, rule for selecting optimal number of process chambers is suggested. It is desirable to select a single process chamber plus a single robot structure for relatively short time process and multi process chambers plus a single robot, namely cluster tool for relatively long time process. Third, throughput variation between equipments due to the wafer transfer time variation is analyzed, especially for the process whose processing time is less than critical process time. And the throughput and the wafer transfer time of the equipments in our fabrication line are measured and compared to the analysis.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.2
• /
• pp.195-202
• /
• 2004

This paper presents the fabrication and evaluation of mechanical behavior for a peristaltic micropump by flow simulation. The valve-less micropump using the diffuser/nozzle is consists of the lower plate, the middle plate, the upper plate and the tube that connects inlet and outlet of the pump. The lower plate includes the channel and the chamber, and the plain middle plate are made of glass and actuated by the piezoelectric translator. Channels and a chamber on the lower plate are fabricated on high processability silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The upper plate does the roll of a pump cover and has inlet/outlet/electric holes. Three plates are laminated by the aligner and bonded by the anodic bonding process. Flow simulation is performed using error-reduced finite volume method (FVM). As results of the flow simulation and experiments, the single chamber pump has severe flow problems, such as a backflow and large fluctuation of a flow rate. It is proved that the double-chamber micropump proposed in this paper can reduce the drawback of the single-chamber one.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.603-607
• /
• 2009

A Ni/Cr plating process has been developed for applying to inner wall of liquid rocket engine(LRE) thrust chamber. Ni plating conditions were selected through thermal shock test and endurance verification of the plating layers was performed through hot firing test of a subscale thrust chamber with Ni/Cr plating. Test results showed that a crack or separation of the plating layers was not found. Judging from the results, Ni/Cr plating could be applied to LRE thrust chamber as a substitute of air plasma sprayed ceramic coating which is presently being used.

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

• Electrical & Electronic Materials
• /
• v.8 no.6
• /
• pp.774-779
• /
• 1995

Process optimization experiments based on the Taguchi method were performed in order to set up the optimal process conditions for the contact oxide etching process module which was built in order to be attached to the cluster system of multi-processing purpose. In order to compare with Taguchi method, the contact oxide etching process carried out with different process parameters(CHF$_{3}$/CF$_{4}$ gas flow rate, chamber pressure, RF power and magnetic field intensity). Optimal etching characteristics were evaluated in terms of etch rate, selectivity, uniformity and etched profile. In this paper, as a final analysis of experimental results the optimal etching characteristics were obtained at the process conditions of CHF3/CF4 gas flow rate = 72/8 sccm, chamber pressure = 50 mTorr, RF power = 500 watts, and magnetic field intensity = 90 gauss.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.3
• /
• pp.271-278
• /
• 2008

A study has been conducted on the bulging process of liquid rocket engine nozzle which is essential to the manufacturing regenerative cooling combustion chamber. Mechanical properties of the material used for the bulging were experimentally obtained by tension tests. Deformation of the bulged nozzle was confirmed by a structural analysis. The developed bulging process and the deformation analysis result were confirmed by manufacturing of the bulged nozzle specimens and the bulging test. There has been a bulging failure among 7 bulged specimens due to the necking of the material. The cause of necking was investigated by comparing microstructure of the material. The investigation has revealed grain size of the material has considerable effect on the occurrence of the necking.

• Particle and aerosol research
• /
• v.12 no.3
• /
• pp.57-63
• /
• 2016

The laser-induced breakdown spectroscopy (LIBS) has been used for rapid detection of elemental compositions of various materials in multi-media (solid, liquid, gas, and aerosols). In this study, the aerosol-LIBS has been developed for real-time monitoring of process-induced particles produced during the semiconductor manufacturing. The developed aerosol-LIBS mainly consists of laser, optics, spectrometer, and aerosol chamber. A new aerosol chamber was constructed for the aerosol-LIBS to be applied for various semiconductor manufacturing process, including exhaust tubes, and low pressure and high temperature chamber. The aerosol-LIBS was evaluated by using laboratory generated aerosols for detection of various elements. As a result, P, Fe, Mg, Cu, Co, Ni, Ca, Na, and K emission lines were successfully detected by the aerosol-LIBS. Further evaluation of the aerosol-LIBS is being conducted.