Myung-Ryul Choi

Effect of pole and slot combination on noise and vibration in permanent magnet synchronous motor

This paper investigates the effect of pole and slot combination on the vibration and noise in permanent magnet synchronous motor (PMSM). Two PMSMs that have the same performances but different pole and slot combinations are studied. A numerical analysis process for the vibration is introduced. First, by using the electromagnetic field finite element analysis (FEA) and Maxwell stress tensor method, the radial forces of these two motors are analyzed. In order to evaluate the effect of the radial force on the vibration, then the equivalent magnetizing current method is used to calculate the local force which then is employed in the mechanical FEA analysis. Finally, an experiment is processed to test the vibration and noise of these two motors, and verify the proposed analysis process. The effect of the pole and slot combination on the noise and vibration are revealed.

A contrast enhancement method using dynamic range separate histogram equalization

In this paper, a contrast enhancement method using dynamic range separate histogram equalization (DRSHE) is proposed. Histogram equalization (HE) method is widely used for contrast enhancement. However, HE is not suitable for consumer electronic products directly because it may cause side-effects such as washed out appearance and false contouring due to the significant change in brightness. DRSHE separates the dynamic range of histogram into k parts and resizes the grayscale range based on its area ratio. Then intensities of histogram are uniformly redistributed in resized grayscale range. DRSHE uses weighted average of absolute color difference (WAAD) in order to emphasize the edge of original image and moderate the histogram variation effectively. We introduced a linear adaptive scale factor to reduce excessive changes in brightness. The experimental results show that DRSHE suppresses unintended changes in brightness and preserves naturalness of the original image compared with conventional methods.

An image interpolator with image improvement for LCD controller

An image interpolator with image improvement is proposed and implemented for a FPD (flat panel display) in this paper. We propose an adaptive pseudomedian filter for the interpolation of images and a real-time contrast controller for image improvement. The proposed interpolation algorithm is based on a pseudomedian filter and uses transposed sub-windows according to the correlation of pixels in the image. The proposed contrast controller uses improved histogram stretching methods and does not require field and frame memory for processing the pixels. The operation of the proposed method has been verified and designed using computer simulation and VHDL. The proposed method achieves better performance than the others from the point of view of the edge and local characteristics.

A real-time field-sequential stereoscopic image converter

We propose a real-time stereoscopic image converter that can generate stereoscopic images with different perspective depth using motion parallax from a 2-D image. Computing the motion parallax between two adjacent 2-D images using the proposed method for motion detection, region segmentation and depth map generation generates the stereoscopic image. We have compared the stereoscopic depth of the proposed method with that of the conventional method. The proposed converter is designed and implemented by using a FPGA and verified by evaluating the field-sequential stereoscopic image on a TV. This converter can automatically produce a realistic 3-D effect regardless of the direction and velocity of a moving object in the 2-D image.

Efficient image enhancement technique by decimation method

In this paper, an efficient image enhancement method is proposed. The proposed algorithm consists of three blocks: the decimation filter, the decision block, and the contrast enhancement. It employs a probability density value in order to control a sudden change in image-brightness. In addition, the proposed algorithm uses a spatial decimation method. It reduces the amount of computation required for image enhancement by using the images generated by spatial decimation method. For a real-time processing, CDF values are calculated by using a first order linear interpolation method. From the simulation results, the proposed method shows better performance and significant reduction in the computational cost compared to a conventional method. The proposed method can be used in the display devices such as LCD TV and PDP TV that require the image enhancements.

A design of contrast controller for image improvement of multi-gray scale image

In this paper, we propose a contrast control for image improvement of multi-gray scale image. The proposed method does not require filed and frame memory for computed data. In addition, we propose that a contrast control can improve image regardless of input gray level. The proposed method can be easily applied to the FPD for real-time processing because of its lower hardware complexity compared to conventional methods. Also it can flexibly control the contrast of input gray level by varying the weight values that control the contrast range. The function of the proposed method has been verified using Synopsys VHDL and computer simulation. In addition, its results show that the proposed method can effect image improvement.

Congestion Control for Mixed TCP and UDP Traffic

In this letter, we propose a protocol sensitive random early detection algorithm for active queue management to improve fairness between TCP and UDP flows and to reduce delay time with small overheads. The algorithm classifies the packets into responsive and unresponsive flows, and applies the RED algorithm individually to each classified group. Using ns-2 simulations, we showed the effectiveness of the proposed PSRED algorithm compared with several well-known AQM schemes, such as RED and RED-PD algorithms.

Implementation of MEBP learning circuitry with simple nonlinear synapse circuits

MEBP (Modified Error Back-Propagation) learning rule has been implemented using simple nonlinear synapse circuits. The simple nonlinear synapse circuit is suitable for implementation of artificial neural networks using standard CMOS technology since it requires large number of neurons. The learning circuitry consists of nonlinear synapse circuits, sigmoid circuits, and linear multipliers, whose output voltage is uniquely determined by any pair of learning input patterns. The proposed learning circuitry is applied for 2/spl times/2/spl times/1 and 2/spl times/3/spl times/1 multilayered feedforward neural network model. MEBP rule has been simulated successfully via C programmed software implementation. And its hardware implementations have been verified by using HSPICE circuit simulator. The proposed learning circuitry is very suitable for the future implementation of the large-scale neural networks or fuzzy processors including on-chip learning.

Real-time moving automotive vehicle identification system (AVIS)

A real-time moving automotive vehicle identification system (AVIS) has been developed for intelligent vehicle highway systems (IVHS). AVIS consists of 3 major elements: invisible bar-code material, optical scanner, and DSP board. The invisible bar-code material reflects only the specific wavelength light (1500 nm). The optical scanner developed can read the invisible bar-code data only at the corresponding wavelength light. The TI TMS320C31 digital signal processing (DSP) board has been implemented. The DSP board processes the bar-code data obtained from the optical scanner through the invisible bar-code. The DSP board operates at 33 MHz with the image processing algorithm which includes error-detecting and error-correcting capabilities. The system has been tested and the results show that the AVIS performed successfully. The AVIS is expected to be applied to the non-stop toll gate and violation enforcement system.

A multimode-interferenced electrooptic TE/TM mode splitter

TE/TM mode splitting is an important integrated-optic function for fiber communication system and fiber sensors, where orthogonal polarization states of the signals are particularly emphasized. Guided-wave TE/TM mode splitting has been demonstrated in LiNbO/sub 3/, III-V compound semiconductors and polymers. They used an asymmetric Y-junction with different preferences of polarizations, a double mode waveguide with different coupling lengths for TE and TM modes, and the photo-bleaching induced birefringence, respectively. We present a novel TE/TM mode splitter utilizing the multimode interference and the linear electrooptic (LEG) effect, It employs a new operating principle, and shows several important characteristics: high extinction ratio, low excess loss, easy fabrication and large fabrication tolerance, and integratibility with other photonic devices.