• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.1
• /
• pp.122-129
• /
• 2004

Finite element analysis was performed to analyze structural safety of a new heavy-duty direct injection diesel engine. A half section of the in-line 6-cylinder engine was selected as a computational domain. A mapping method was used to project heat transfer coefficients from CFD results of engine coolant flow onto the FE model. The accurate setting of thermal boundary condition on the FE model was expected to result in improved prediction of temperature, cylinder bore distortion, and stresses. Characteristics of high cycle fatigue were investigated by assuming the engine was operated under the following five loading conditions repeatedly; assembly force, assembly force with thermal loading, alternating maximum gas pressure loading at each cylinder combined with assembly force and thermal loading. Distribution of fatigue safety factor was calculated by using it Haigh diagram in which the maximum and the minimum stresses were selected from the five loading cases.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.1 no.1
• /
• pp.1-14
• /
• 2000

This paper is concerningon the development of cross-flow fan (CFF) for vehicles. CFF is widely usedhome-appliance products. This work mainly Intends developing CFF only for an automobile. In order to do that, new design involving blade shapes is proposed with enough performance for the operation. Spacially three steeps are proceeded for blade design. injection conditions for manufacturing, and capacity test for fluid mechanics. The present methodologies are to find optimal design for the blades and conditions for the injection process. This project has continued since last two years and finally succeeded.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.2
• /
• pp.310-317
• /
• 2002

In the present study, an experimental study of natural convection in a partitioned 2D square enclosure has been carried out. The square enclosure consist of two adiabatic vertical walls and the upper cold and the lower hot walls. A partition is positioned perpendicularly at the center of the left vortical insulated wall. The PIV measurements were performed with the variations of Rayleigh number, partition length and inclination of the enclosure. The working fluid is water with Prandtl number of 6.996 at 20$\^{C}$. The captured images were analyzed by using a cross-correlation (two-frame/single-exposure) PIV method.

• Journal of the Korean Society of Visualization
• /
• v.6 no.1
• /
• pp.3-16
• /
• 2008

Controlling fluid flows in micro scales is a non-trivial issue among those who are involved in designing lab-on-chips. Pumping and mixing by using electrokinetic principles has been popular in that the method requires a few parts and it is easy to control. This paper explains the basic mechanism of the electroosmotic flows caused by AC together with presenting some numerical results. In particular, the fundamental, physical idea involved in the mechanism will be illustrated in terms of the kinematic aspect. Since the electroosmotic flows are mainly driven by the motion of ions, we also demonstrate the ion motions by using the numerical-visualization method.

• Journal of Power System Engineering
• /
• v.22 no.6
• /
• pp.80-86
• /
• 2018

A damper is a hydraulic device designed to absorb or eliminate shock impulses which is acting on the sprung mass of car body. It converts the kinetic energy of the shock into another form of energy, typically heat. The main mechanism for providing damping is by shearing the hydraulic fluid as it flows through restrictions. Since the damping mechanism depends on the flow restrictions, these restrictions are very important in damper design. Damper engineers often try several combinations of valve shims, piston orifices and bleed orifices before finding the best combination for a particular setup on a car. Therefore, the ability to tune a damper properly without testing is of great interest in damper design. For this reason, many previous researches have been done on modeling and simulation of the damper. This paper explains a genetic algorithm method to find the optimal parameters for the design objective and the simulation results agree well with the targeted damping characteristics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.04a
• /
• pp.200-203
• /
• 2011

Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.18 no.33
• /
• pp.123-134
• /
• 1995

After the introduction of ATM as a proper technology for B-ISDN, there have been many research efforts to realize ATM networks. But a computationally tractable modelling technique which reflects diverse characteristics of the ATM traffic accurately is not available yet. In this study, we try to establish an accurate but still convenient ATM traffic model. We first introduce the modelling technique for the voice traffic based on the fluid flow approximation. Then we present a traffic model for the mixed traffic from multiple video sources and voice sources. The video source model is based on the 3 state continuous time Markov chain. The accuracy of the model is demonstrated by some comparison results with respect to simulation.

• Journal of the Korean Society of Visualization
• /
• v.20 no.3
• /
• pp.67-73
• /
• 2022

Underwater environmental pollution caused by microplastic particles is considered to be one of the most serious problems in many oceans and countries nearby. Previous academic studies or field technologies tried to remove the micro-sized particles are often energy-consuming and costly, so it is hard to be employed for the actual uses. In this study, the mechanism of removal of micro-sized polyethylene spheres (size in order of 100㎛) using a rising bubble is experimentally investigated. It is found that the particles are either affected by bubble wake, thus translocated close to the water surface, or pushed far away by the surrounding fluid flow, depending on their initial position relative to the bubble. By scrutinizing the visualized behaviors of bubble-particle interaction, we draw the governing parameter, i.e., the polar angle between the particle and the bubble, to determine the effective capturing of the particles with a rising bubble.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.12
• /
• pp.1175-1183
• /
• 2013

Even if some CFD software developers and its users think that a state-of-the-art CFD software can be used to reasonably solve at least single-phase nuclear reactor safety problems, there remain limitations and uncertainties in the calculation result. From a regulatory perspective, the Korea Institute of Nuclear Safety (KINS) is presently conducting the performance assessment of commercial CFD software for nuclear reactor safety problems. In this study, to examine the prediction performance of commercial CFD software with the porous model in the analysis of the scale-down APR (Advanced Power Reactor Plus) internal flow, a simulation was conducted with the on-board numerical models in ANSYS CFX R.14 and FLUENT R.14. It was concluded that depending on the CFD software, the internal flow distribution of the scale-down APR was locally somewhat different. Although there was a limitation in estimating the prediction performance of the commercial CFD software owing to the limited amount of measured data, CFX R.14 showed more reasonable prediction results in comparison with FLUENT R.14. Meanwhile, owing to the difference in discretization methodology, FLUENT R.14 required more computational memory than CFX R.14 for the same grid system. Therefore, the CFD software suitable to the available computational resource should be selected for massively parallel computations.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.236.2-236.2
• /
• 2010

The tidal current power is the power plant by installing the turbine or rotor where the tidal speed is fast. This system converting the horizontal movement to rotating energy. Tidal power turbine is needed for the dam to utilize the pressure difference. However, tidal current power using the only flow. The tidal current power was evaluated as the impact on the marine environment surrounding was less and the development of eco-friendly way. In this article, we calculated the effect of tidal current turbine on the tidal power generating by mean of CFD. With these calculated results, we checked the possibility of tidal current power using tidal power plant the discharge gate.