• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.10a
• /
• pp.126-131
• /
• 2004

A numerical code for cavitation is developed based on pressure-based algorithm. The k-\varepsilon$ model (with wall function) is used for turbulence, and volume transport equation is used for cavitation model. The compressibility is not considered for the flow field is low speed.

• Journal of Korean Association for Spatial Structures
• /
• v.21 no.1
• /
• pp.12-17
• /
• 2021

• Journal of the korean Society of Automotive Engineers
• /
• v.13 no.6
• /
• pp.90-100
• /
• 1991

This paper represents the analysis of the sheet drawing by applying the Matrix method to Hill's slip-line field for small reduction and indirect type slip-line field in case of large reduction. Results of the analysis represent the relation between the reduction ratio and the die wall pressure, mean drawing stress through rough die. The limitation on the use of this slip-line field is described. When the reduction ratio is given, the optimum die angle is analyzed in this paper.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1991.10a
• /
• pp.312-331
• /
• 1991

Top-down Method of basement construction technique has been applied for building of the deep basement car park the close proximity of priceless historic buildings in LONDON. Numerical analysis for the prediction of ground movement of the surrounding buildings was performed in order to compare the field data at the various stages of excavation and support. The predicted results from the elasto-plastic analytical method were compared with the observed data and the agreement is very satisfactory. It may be concluded that the system of diaphragm wall supported by the permanent base slabs (Top-Down Method) was proved to be the most effective technique in terms of reducing any critical damage to the surrounding buildings.

• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.139-142
• /
• 2004

X-band Waveguide slot way antenna is developed for heliborne MTD radar applications. The antenna is composed of multi-layer waveguide structures. Each of them has it's own functions, such as, radiation, power/phase distribution, coupling, etc. Broad-wall offset slots are used for radiators, inclined slots on broad-wall for power distribution to radiating(branch) waveguide, some kind of coaxial probe structures for in-phase coupling and H-plane T-junction power dividers. Antenna is realized by precision machining and careful assembly. It is tested and measured by 3m${\times}$l.7m planar near-field probe, which is set-up in MTG. Far-field calculations have good agreement in tolerable bounds. Special but necessary process such as brazing, will increase the accuracy and performance. Results show promising possibilities of future applications for real systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.489-496
• /
• 2008

This paper investigates active noise control of ducts using Filtered-x Least Mean Square (FXLMS) algorithms to reduce noise transmission. Single channel FXLMS (MFXLSM) and multiple channel FXLMS (MFXLMS) algorithms are used to implement the active control systems. The transmission loss is significantly increased by SFXLMS but the sound pressure level (SPL) at the upstream of the error sensor is increased while that of downstream is very low. This increase of the upstream SPL causes the duct wall to vibrate and so to radiate noise. To prevent the wall vibration generated by the sound field upstream, global sound field control is required. To reduce SPL globally along the duct, active noise control using MFXLMS is implemented. We can then obtained globally reduced SPL. It is found experimentally that the vibration level, and so the radiated noise level. can be reduced by the active noise control using MFXLMS.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.404-407
• /
• 2004

The construction of high-rise buildings is increased. The Vertical Member of tall buildings is inherently shortened and it causes several seriously problems such as tilting of slab, crack within partition wall, deformation of curtain wall. This also affects structural stability by inducing unexpected stress to the structural members such as outrigger. In this study, the column shortening according to revised field information and to compare the analysis results the actual field measurement. Pusan The $\#$, a 51-story apartment building which is currently under construction was chosen for the case study.

• 한국연소학회:학술대회논문집
• /
• 2004.06a
• /
• pp.192-198
• /
• 2004

A numerical study was conducted to determine the effects of high temperature air, including equivalent ratio on flow field, temperature, evaporation, and overall temperature distribution in gas turbine combustor. A sector model of a typical wall jet can combustor, featuring introduction of primary air and dilution air via wall jet, was used in calculations. Flow field and temperature distribution were analyzed. Operating conditions such as inlet temperature and overall equivalent ratio were varied from 373 to 1300 K, and from 0.3 to 0.6, respectively, while any other operating conditions were fixed. The RNG ${\kappa}-{\varepsilon}$ model and eddy breakup model were used for turbulence and combustion model respectively. It was found that the increase with the inlet air temperature, velocity in the combustor is accelerated and evaporation of liquid fuel is not affected in primary zone, high temperature inlet air enhances the evaporation and improves overall temperature distribution factor.

• Journal of the Korean Magnetics Society
• /
• v.10 no.3
• /
• pp.143-148
• /
• 2000

We made MnZn ferrites by conventional ceramic processing method and observed magnetic domain structures by Bitter method. The Bitter method revealed that the domain structure of the surface is stripe-like. When a magnetic field was applied, the domain wall motion was observed during the initial magnetization process and the irregular motion of domain wall or domain rotation was observed near the saturation magnetic field (90∼120 Oe).

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.11a
• /
• pp.353-356
• /
• 2006

Convective heat transfer coefficient was measured around a secondary jet ejected into the supersonic flow field. Wall temperature distribution was measured on the surface, which the constant heat flux condition is applied. According to jet to freestream momentum ratio, the secondary flow was penetrated into the supersonic flow field. During the test, two dimensional thermal image of a wall temperature is taken by an infra-red camera. Experiments were performed under the testing condition of freestream Mach number of about 3, stagnation pressure of 630 kPa and Reynolds number of $3.0{\times}10^6$.