• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.35 no.12
• /
• pp.579-585
• /
• 1986

A Reversed Field Pinch(RFP) Plasma automatically forms the reversed field configuration in a stable state by the self-reversal phenomenon. But this process of formation of the reversed field configuration has a problem that instabilities occur. In order to form a RFP configuration in a stable state by removing instabilities, this experimental study attempts to restrain Toroidal magnetic fields and supplement Toroidal flux by employing high frequency rotating fields. As a result, the reversed magnetic field configuration is stably formed in a short period because high frequency rotating fields can deflect poloidal currents and produce magnetic fields in the Toroidal direction.

• 유체기계공업학회:학술대회논문집
• /
• 1998.12a
• /
• pp.97-104
• /
• 1998

The objective of this study is to understand the generation mechanism of sound and to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan. Lowson's method is used to predict the acoustic pressure in a free field. A DVM(discrete vortex method) is used to model the centrifugal fan and to calculate the flow field. In order to compare the experimental data, a centrifugal fan and wedge introduced by Weidemann are used in the numerical calculation and the results are compared with the experimental data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.288-288
• /
• 2010

In this study radio rotatiing field is used in order to form the stable reversed field configuration. The experimental study removing the flux conserving ring not so as to conserve toroidal flux, it was found that there occurred a rapid formation of a stable reversed field configuration, in which toroidal flux was increased shaping reversed field configuration and F-$\Theta$ locus traced close to BFM because it started below F value.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.2066-2070
• /
• 2003

This experimental study describes the propagation characteristics and suppression of the impulse noise emitted from the exit of a perforated pipe attached to the open end of a simple shock tube. The experiment is performed through the systematic change of the shock wave Mach number and the geometrical parameters such as the porosity, hole diameter and length of the perforated pipe. The experimental results for the near and far sound field are presented and explained in comparison with those for a straight pipe. The results obtained show that for the near sound field the impulse noise strongly propagates toward to the pipe axis, but for the far sound field the impulse noise uniformly propagates toward to the all directions, indicating that the directivity pattern is almost same regardless of the pipe type. Moreover, the noise reduction performance of perforated pipe depends upon the condition of sound field. For the near sound field the perforated pipe has a little performance to suppress the impulse noise, but for the far sound field the perforated pipe has little performance to suppress the impulse noise.

• Journal of Biosystems Engineering
• /
• v.17 no.3
• /
• pp.213-222
• /
• 1992

To develop the wireless remote opreating system of walking rice transplanter, this study was carried out for manufacturing the wireless remote control system acting upon the transplanter. The first report of this study contained about the construction and operating method of a developed remote control system for 2-row walking type transplanter. It is the second report about the field test for an experimental transplanter being attached a wireless control system and for a conventional transplanter. The test was executed to investigate the characteristics of velocity, rectilinearity, turning time, interval of roots and of rows, and field capacity in accordance with various engine speeds for an experimental transplanter. The measurements of this test were compared with those of the conventional transplanter. The obtained results were as follows : 1. The operating velocity of the experimental transplanter was faster than the conventional one when the high speed range of the engine but the variances were very large. 2. The rectilinearity, interval of raws and of roots, and the turning time of the experimental transplanter was inferior to the conventional one at some speed ranges of the engine. 3. Field capacity of the experimental transplanter was superior to the conventional one at high speed of the engine. 4. There were some disadvantages for the experimental transplanter to operate, because it was constructed without any aid devices, such as float and hydraulic system for instance. But if the remote control system of this study equip at the modern walking transplanter, it will be improved and utilized without defects which was revealed from this test.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2088-2093
• /
• 2008

In this study, flow field measurement of the Pebble Bed Reactor(PBR) for the High Temperature Gas-cooled Reactor(HTGR) was performed. Large number of pebbles in the core of PBR provides complicated flow channel. Due to the complicated geometries, numerical analysis has been intensively made rather than experimental observation. However, the justification of computational simulation by the experimental study is crucial to develop solid analysis of design method. In the present study, a wind tunnel installed with pebbles stacked was constructed and equipped with the Particle Image Velocimetry(PIV). We designed the system scaled up to realize the room temperature condition according to the similarity. The PIV observation gave us stagnation points, low speed region so that the suspected high temperature region can be identified. With the further supplementary experimental works, the present system may produce valuable data to justify the Computational Fluid Dynamics(CFD) simulation method.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.6
• /
• pp.1518-1528
• /
• 1995

The deformation and departure processes of a bubble attached to the wall are studied experimentally and numerically to understand the phenomena of the nucleate boiling heat transfer enhancement under DC electric field. An air-bubble is injected in a dielectric liquid with different electric fields generated by changing three types of electrode system (Type 1,2 and 3) in the bubble generator. Experimental variables are the electric field strength and the distance and the shape of the electrodes under DC electric field. From experimental results, it is observed that the bubble under Dc electric field is elongated in the same direction as the electric field and the contact angle increases. For the parallel plate electrode which generates a uniform electric field, bubble departure volume doesn't seem to decrease within our experimental range. However, when a needle is raised a few millimeters from the lower electrode to make a nonuniform electric field around the needle, bubble departure volume decreases continuously with the increase of an applied voltage. The reduction effect of bubble departure volume is the most effective under a strong nonuniform electric field generated with Type 3. As the nonuniformity of the electric field due to the shape of a electrode increases, the terminal velocity and the acceleration of a bubble increase largely. For the comparison with visualization results, the deformation of a bubble attached to the electrode is carried out by a numerical method. Numerical results show good agreement qualitatively with experimental results.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 1999.10c
• /
• pp.192-199
• /
• 1999

In order to make the reasonable irrigation planin the reclaimed paddy fields, the estimation of irrigation water requirements by soil textures and water management methods for the normal growth of crops is very important. This study was carried out to determine leaching water requirements before cultivating crops. For the purposes of this study, the physical and chemical properties of soil sampels used in the desalinication experiments were analyzed and change of salinity by supplying water and leaching water were investigated in the experimental field with lysimeters.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.12
• /
• pp.969-976
• /
• 2014

Nowadays, it is required for naval ships to estimate 3D underwater radiated noise pattern in all direction at peak frequencies of hull vibration for the reduction of being detected and doing the effective operation. For this purpose, the numerical method has to be developed to calculate 3D underwater radiated noise pattern with experimental data. It is very difficult to obtain the experimental data for the real ship. Alternative to get the experimental results is to use NAH(near-field acoustic holography) in acoustic tank with experimental model. Application of NAH in acoustic tank for the experimental model needs some investigation of reflection wave from the wall of the acoustic tank and unmeasured zone of the experimental model due to the supporting structure for it. In this study, the effect of reflection wave in the acoustic tank and unmeasured area of the experimental model when using the NAH was investigated with experiment and numerical model. From these, it is known for the error due to reflection wave can be reduced when the distance between the measurement plane and source is being shorten. Also, unmeasured area of the experimental model gives rise to some error in the estimation of the far-field acoustic pressure.

• 한국연소학회:학술대회논문집
• /
• 2013.06a
• /
• pp.107-108
• /
• 2013

An experimental study in the dual swirl burner was conducted to analyze the temperature characteristics in the combustion field. The dual swirl burner consists of a main swirling pre-mixed flame with tangential swirler surrounding a pilot which can stabilize a diffusion flame or a partially premixed flame with vane swirler depending on whether fuel is supplied at the exit plane or further upstream. The purpose of this study is to analyse experimentally the characterization of flame temperature in the reacting zone, specially, according to the various combustor diameters like 80mm, 100mm, 130mm and 150mm(O.D). As a result, the temperatures of combustion field were decreased as the diameter of combustor increased. Therefore, these results can be expected that the larger diameter of combustor tend to emit less NOx emission than the small combustor.