• Journal of Biomedical Engineering Research
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• v.26 no.1
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• pp.31-35
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• 2005

A novel synthetic aperture method for real-time three-way dynamic focusing is proposed, which provides lateral beam patterns represented as the product of Fourier transforms of transmit subaperture, receive subaperture, and a synthetic window function. In the proposed method, all array elements are fired individually and for each firing echo signals are recorded from all elements of a receive subaperture moving along an array with the transmit element. The three-way dynamic focusing is then achieved by employing a synthetic aperture algorithm for two-way dynamic focusing and a synthetic focusing method for transmit dynamic focusing. Both theoretical analysis and computer simulation results show that the proposed method produces ultrasound beams with improved lateral resolution at all depths compared to the conventional phased array imaging and synthetic aperture focusing methods.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.4
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• pp.65-71
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• 1984

The design formular of optical focusing systems cannot be applied to ultrasonic B scanners, which use broadband pulses instead of continuous wave. In this paper, a calculation method is studied for analyzing the propagation of ultrasonic broadband pulse excited by ultrasonic array transducers. Using the results, seveial design parameters such as the number of transducer elements, delay time, and the focal point are determined to obtain high resolution in the ultrasonic dynamic focusing system. A dynamic focusing system with low-noise switching characteristics; which attains lateral resolution of 2-3mm all along the axial direction up to 18 cm with a 3.5 MHz linear array transducer, was implemented.

• Journal of Biomedical Engineering Research
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• v.22 no.4
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• pp.321-330
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• 2001

In this paper, we propose a new synthetic aperture focusing scheme for improving the lateral resolution which is one of the most important factors determining the quality of ultrasound imaging. The proposed scheme enables full round-trip dynamic focusing with approximately limited property. This properties are obtained through transmitting plane waves of which the traveling angle varies with the receive subaperture position, as opposed to stepping the spherical wave source across an array in other synthetic aperture focusing schemes, and employing dynamic focusing in receive. In this paper, the properties of the proposed scheme is analyzed in which a hypothetical infinite line source is used to transmit the plane waves and verified through computer simulation results. Also, we show that the proposed scheme is realizable with an array transducer with a finite aperture size. In summary, it is shown through comparison between the field contours of the proposed scheme and the conventional scheme that the proposed scheme can improve greatly the lateral resolution of ultrasound imaging.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.706-711
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• 2001

A dynamic vibration absorber(DVA) is developed to reduce the excessive focusing vibration of an optical disc drive(ODD) originated from the resonance of an wobble disc. We design the material properties of the DVA by FEM model such as Young's modules, damping coefficient, shapes and dimensions, analyze its dynamic characteristics and provide its design guide line for suppressing the vibration of an optical disc drive. To examine the performance. of the DVA, the vibration of the wobble disc and the feeding system is measured by using a laser vibrometer and the noise level is checked by using microphone. The result shows that the proposed DVA reduces the vibration and. the noise in an optical disc drive.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.149-158
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• 1999

The modern trends of optical storage devices can be characterized by high density in information recording, and high bandwidth in data input/output processing rate. These make servo engineers to face with a new barrier on control system design in much more difficult way. The first step to attack this barrier will be through a systematic modeling for the dynamic characteristics of optical storage drive. in this paper, an analytical dynamic model for an optical storage drive based on FEM is drived, and compared with experimental results. Through this comparison, a practical dynamic model on the focusing and tracking motion of optical storage drive is proposed for the initiation of real control system design problem.

• Proceedings of the Acoustical Society of Korea Conference
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• 1984.12a
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• pp.78-82
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• 1984

The purposed of this paper is to realize two dimensional acoustic image using focusing method. In the experiment, it consists of phase delay part, 14 analog multiplexers, multi-amplifiers, A/D converter, DMA interfacing parts, two linear arrays(resonance frequency 25 KHz, radius 0.75 Cm diac type). Finally in this experimental result, both electrical deflection and dynamic focusing are realized and gets two dimensional acoustic image using focusing method.

• Journal of Biomedical Engineering Research
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• v.9 no.1
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• pp.87-92
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• 1988

In this paper, a new focusing method, to be called the pipelined sampled delay focusing (PSDF), is implemented. This method improves the lateral resolution in ultrasound imaging system. In PSDF, the analog belay lines are no longer necessary because sampling sum process can replace the conventional delay sum process. Also, the method offers continuous dynamic focusing on the resolution pixel basis, and eliminates the constraint that the maximum delay time is less than the sampling interval. Second order sampling is adopted in order to extend the sampling interval.

• Journal of Biomedical Engineering Research
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• v.23 no.3
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• pp.243-251
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• 2002

Synthetic zinc wave employs Pulsed plane wave as transmit beam with linear time delay curve. The received echoes in different transmit directions at different transmit times are superposed at imaging Points with Proper time delay compensation using synthetic focusing scheme. This scheme. which uses full aperture in transmit, obtains a high SNR image, and also features high lateral resolution by using two way dynamic focusing at all imaging depths. In this Paper, we consider the Problems in realization of synthetic zinc wave. Also. we have applied the scheme to obtain phantom and in-vivo images using a linear array of 5 MHz. In phantom test. experimental images show high resolution over a more extended imaging depth than conventional fixed Point transmit and receive dynamic focusing schemes In-vivo images show that the resolution could not overcome conventional focusing systems because of motion blurring and(or) aberration of tissue. but the frame rate tan be increased by a factor of more than 5 compared to conventional focusing schemes. with competitive resolution at all imaging depths .

• Journal of Distribution Science
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• v.20 no.2
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• pp.31-41
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• 2022

Purpose: Developing and nurturing supply chain dynamic capability is one of the leading solutions to create competitive advantages, maintain growth and sustainable development for businesses. The study was conducted to experimentally confirm the impact of supply chain dynamic capability on competitiveness and business efficiency for Vietnamese wood enterprises. Research design, data and methodology: The study surveyed 236 managers of Vietnamese wood manufacturing and distribution enterprises. The authors applied the structural equation modeling (SEM) to analyze the relationship between the dynamic capability of the supply chain and the competitiveness, business efficiency of enterprises to achieve those goals. Results: The results show that businesses owning supply chain dynamic capability will have better competitiveness and business efficiency. Especially, in the context of Vietnamese wood sector, the larger the scale of business, the more profound the impact of supply chain dynamic capability on competitiveness and business efficiency. Conclusions: Focusing on developing supply chain dynamics would be a promising solution to improve the competitiveness of Vietnam's wood enterprises in the global market.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.116-122
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• 2012

The purpose of this study is on the development of 3-D conductive pattern fabrication system using laser. For development 3-D direct patterning system, we used the dynamic focusing, the laser power stabilizer and the auto aligning techniques. These technologies are already used commercially. However operation and control integrated system for 3-D direct patterning are not yet developed. The objective of this paper is to introduce laser direct structuring and develop the operating and integration system. Also we implemented new application of laser direct structuring.