• The Transactions of the Korean Institute of Power Electronics
• /
• v.7 no.3
• /
• pp.281-288
• /
• 2002

This paper has realized a control system of a vibrator using PM excited Transverse Flux Linear Motor(TFLM). Proposed vibrator can supply a vibration force up to 700[N] at rated current, wide operation range of vibration displacement and high frequency for a tested structure. Also, volume of a vibrator system can be decreased because of a high trust force rato(a thrust force per weight=N/Kg). A proposed vibrator instead of a hydraulic vibrator can improve efficiency and have may advantages of maintenance and management. A desired value command is a vibration frequency and displacement in a controller for a vibrator system and a controlled values we a instant position and velocity of a mover Output value of the controller is phase current controlled by PWM converter. In this research, Dynamic simulation has been executed for analysis of a control algorithm and dvnauuc characteristics and is compared with experimental result.

• Journal of the Semiconductor & Display Technology
• /
• v.4 no.1 s.10
• /
• pp.9-16
• /
• 2005

In this paper, with loosely coupled transformer Relies-parallel resonant type DC/DC converter is analyzed and adopted to the power source of a TFLM(Transverse Flux Linear Motor). To get more efficient operating mode of the series-parallel resonant type DC/DC converter, theoretical analysis using normalized parameters are accepted. The analysis includes a specially made ferrite transformer with two separately wound half cores in order to evaluate analytically and experimentally the changes in magnetizing the leakage fluxes and inductances caused by the distance between the halves. The proposed converter must be operated in switching Pattern III among the three switching patterns for the Zero Voltage Switching operation. According to Pulse Frequency Modulation(PFM) control method, the output voltage of the proposed circuit can be controlled. The results of the theoretical development are compared with practical measurements from a prototype system.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.776-779
• /
• 2002

This paper describes the magnetizer design of highly saturated magnetic circuit by high external field. The magnetizer is loaded by a capacitor bank with impulse currents to reach high magnetic flux-density(typically 5[T]). Magnetizing current come out from magnetizing system is simulated by analytic method and transient FEM, also field distributions of the magnetizer are analyzed.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.12 no.5
• /
• pp.1150-1157
• /
• 1988

Two-dimensional turbulent plane jet which is under the pressure gradient in the transverse direction is studied numerically. Full Navier-Stokes equations are used to correctly account for the pressure variation in the transverse direction. Using the standard k-.epsilon. turbulence model as a closure relationship, a time marching procedure gives the velocity field. The temperature fields are obtained for two different cases : (1) Hot jet is issued into the cold still air, and (2) Hot jet is issued into the surrounding across which exists a temperature difference. The velocity and temperature fields along with other flow and heat-transfer characteristics for two different pressure gradients are presented. A simple formula that relates the jet trajectory to the pressure gradient is also proposed. The mass flux in the longitudinal direction and the jet halfwidth seem insensitive to the pressure gradient. However, the pressure gradient increases the heat flux in the longitudinal direction as well as in the transverse direction.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.125-125
• /
• 2023

Estuarine dams are dams constructed in estuaries for reasons such as securing freshwater resources, controlling water levels, and hydroelectric power generation. These estuarine dams alter the flow of freshwater to the coastal ocean and the tidal properties of the estuaries which has implications for the estuaries' circulation and sediment transport. A previous study has analyzed the effect of estuarine dams on 1D (along-channel) circulation and sediment transport. However, the effect of estuarine dams on the transverse variability of along-channel and across-channel circulation and sediment transport has not been studied and is not known. In this study, a coupled hydrodynamic-sediment dynamic numerical model (COAWST) was used to analyze the transverse variability of along-channel and across-channel flow and sediment transport in estuaries with estuarine dams. The estuarine dam was found to change the 3D structure of circulation and sediment transport, and the result was found to depend on the estuarine type (i.e., strongly stratified (SS) or well-mixed (WM) estuary). The SS estuary had inflow in the channel and outflow over the shoals, consistent with estuarine circulation. Longer discharge interval reduced the estuarine circulation. The WM estuary had inflow over the shoals and outflow in the channel, consistent with tide-induced circulation. As the estuarine dam was located nearer to the estuary mouth, the tide-induced circulation was reduced and replaced with estuarine circulation. The lateral circualtion was the greatest in the tide-dominated estuaries. It was reduced and changed direction due to differential advection change as the dam was located nearer the mouth. Overall, the WM estuary transverse flow structure changed the most. Lateral sediment flux was important in all estuaries, particularly for transporting sediments to the tidal flats.

• Nuclear Engineering and Technology
• /
• v.31 no.2
• /
• pp.236-255
• /
• 1999

An improved mechanistic model was developed to predict a convective boiling critical heat flux (CHF) in the vertical round tubes with uniform heat fluxes. The CHF formula for subcooled and low quality boiling was derived from the local conservation equations of mass, energy and momentum, together with appropriate constitutive relations. The model is characterized by the momentum balance equation to determine the limiting transverse interchange of mass flux crossing the interface of wall bubbly layer and core by taking account of the convective shear effect due to the frictional drag on the wall-attached bubbles. Comparison between the present model predictions and experimental CHF data from several sources shows good agreement over a wide range of How conditions. The present model shows comparable prediction accuracy with the CHF look-up table of Groeneveld et al. Also the model correctly accounts for the effects of flow variables as well as geometry parameters.

• Proceedings of the KIEE Conference
• /
• 1999.07a
• /
• pp.34-36
• /
• 1999

2 phase 8 pole HB type LPM(linear pulse motor) has the suitable structure for it's microstep drive. Hence, if this LPM will be drived by this method, the limited(mechanically) step resolution can be increased further and vibration and noise can be decreased considerably. But, It is difficult that this LPM was analyzed in detail because of it's complex magnetic circuits to be composed the LF(longitudinal flux) and TF(transverse flux.) path. If LPM was analyzed by the approximate 2D model, we could not be obtained satisfactory result. Therefore, It is necessary to be analyzed the 3D model in detail for the more satisfactory results. In this paper, we obtain 3D flux distribution of the mover using by 3D FEM(finite element method)

• The Transactions of the Korean Institute of Power Electronics
• /
• v.11 no.5
• /
• pp.471-479
• /
• 2006

Automatic transfer equipments of manufacturing and process line trend toward big size as LCD glass is big size, heavy weight. The conventional stocker uses rotational motor and mechanical power converter device as travel axis of stocker crane and then frequent maintenances by complex structure and mechanical friction are required. Also it has problem to minimize the particle generation. To solve these problems, this paper verified the performance of permanent magnet(PM) excited transverse flux linear motor(TFLM) that is big power density per unit volume applied for travel axis of 7 generation stocker that is being big size, high power, long distance by the experiment based on proposed control algorithm, controller and power converter device.

• Proceedings of the KIEE Conference
• /
• 2005.10c
• /
• pp.147-149
• /
• 2005

On this study, we optimized maximizing thrust force of weight ratio and minimizing detent force of weight ratio at the TFLM(Transverse Flux Linear Motor) using design of experiments by the table of orthogonal array, characteristic function and analysis of means(ANOM), For two functions or more, the effectiveness of design change can be evaluated in accordance with change in design parameters. Also, The stator and mover weight of TFLM is reduced by up to 20 percent while its thrust force of weight ratio and detent force of weight improved. From now on, we are going to apply the required technique to design various uses and shares of the TFLM.

• Korean Journal of Hydrosciences
• /
• v.6
• /
• pp.67-79
• /
• 1995

The reattachment of buoyant efflluent to a shore in a crossflow is investigated experimentally. The effluent is prodeced by discharging heated water through a projected side channel into a confined crossflow of the same depth. In the projecting effluent, the size of recirculating region, which is formed by deflected thermal plume on the lee of the effluent, tends to increase, but the maximum temperature decreases in the direction of the crossflow and it has more uniform transverse spreading compared to non-projected type. The heat flux across the crossflow is found to be independent of the projceted length of the side channel under relatively high buoyancy flux on the contrary to low buoyancy flux. The reattachment of th effluent can be specified by both velocity ratio and densimetric Froude number, whereas only the velocity ratio is governing factor to the reattachment of the effluent in the case of non-projecting type.