• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.64-67
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• 1992

To improve signal-to-noise ratio in sodium image, short echo time (2-3 ms) and long data acquisition (10-20 ms) protocols are used. Sodium in biological specimens demonstrates a bi-exponential decay of transverse magnetization and the fast decaying component of the sodium signal results in the reconstruction of images which are blurred significantly. The spatially-dependent nature of the blurs are due mainly to the presence of short local transverse relaxation values (0.7-3 ms) of sodium in tissue. We present an algorithm that corrects for object-dependent blurs due to fast-decaying T2 and improves the computational behavior of the algorithm by incorporating a relaxation parameter into the iterative process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1132-1135
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• 2002

In this paper, we propose a phase-locked loop (PLL) with dual loops in which advantages of both loops can be combined. Frequency-locked loop (FLL) which is composed of two frequency-to-voltage converters (FVC) and an amplifier makes the frequency synchronize very fast and output signal is synchronized in phase with the input reference signal by charge pump PLL. This structure can improve the trade-off between acquisition behavior and locked behavior.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.3
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• pp.237-242
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• 2016

The major advantage of slip-ring technology in Spiral CT is that it facilitates continuous rotation of the x-ray tube, so that volume data can be acquired from a patient quickly. Not only for such a fast scan, but also for the dose reduction purpose, high signal-to-noise ratio and fast data acquisition system is required. In this study, we have built a multi-channel photodetector and multi-channel data acquisition system for CT application. The detector module consisted of CdWO4 crystal and Si photodiode in 16 channels. For the performance test of the preamplifier stage, both the transimpedance and switched integrator types are optimized for the photodetector modules. Switched integrator showed better noise performance in the limited bandwidth which is suitable for the current CT application. The control sequence for data acquisition and 20 bit ADC is designed with VHDL(Very High Speed Integrated Circuit Hardware Description Language) and implemented on FPGA(Field Programmable Gate Array) chip. Our Si photodiode detector module coupled to CdWO4 crystal showed comparable signal with other commercially available photodiode for CT. Switched integrator type showed higher SNR but narrower bandwidth compared to transimpedance preamplifier. Digital hardware is designed by FPGA, so that the control signal could be redesigned without hardware alteration.

• Investigative Magnetic Resonance Imaging
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• v.25 no.4
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• pp.229-251
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• 2021

Arteriosclerosis is the leading cause of stroke, with a fatality rate surpassing that of ischemic heart disease. High-resolution vessel wall magnetic resonance imaging is generally recognized as a non-invasive and panoramic method for the evaluation of arterial plaque; however, this method requires improved signal-to-noise ratio and scanning speed. Recent advances in high-density head and neck coil arrays are characterized by broad coverage, multiple channels, and closefitting designs. This review analyzes fast magnetic resonance imaging from the perspective of accelerated algorithms for vessel wall imaging and demonstrates the need for effective algorithms for signal acquisition using advanced radiofrequency system. We summarize different phased-array structures under various experimental objectives and equipment conditions, introduce current research results, and propose prospective research studies in the future.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.437-445
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• 2008

This paper deals with the experimental assessment of the vibration suppression of the smart structures. First. we have presented a new high-speed active control system using the DSP320C6713 microprocessor. A peripheral system developed is composed of a data acquisition system, N/D and D/A converters, piezoelectric (PZT) actuator/sensors, and drivers for fast data processing. Next, we have tested the processing time of the peripheral devices, and provided the corresponding test results. Since fast data processing is very important in the active vibration control of the structures, we have focused on achieving the fast loop times of the control system. Finally, numerous experiments were carried out on the aluminum plate to validate the superior performance of the vibration control system at different control loop times.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.9
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• pp.1253-1258
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• 2014

In this paper, we propose the fast and efficient detection method using the continuous measurement technique for the gamma-ray signal acquisition. This method is improved than the conventional method for the getting information of the radiation distribution. First, we implement the stereo radiation detection system using gamma-ray sensors and the motion controller. We apply continuous measurement technique to the gamma-ray detector and conduct gamma-ray irradiation test for the comparison of detection techniques. The results show that the continuous measurement technique has the high efficient performance than the conventional method.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.141-146
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• 2005

In this paper, we propose to extend the TSS-LS (Two-Step Search scheme with Linear search based Second step) scheme which was already proposed by the authors for coherent UWB (Ultra Wide Band) systems, to rapid and reliable acquisition of noncoherent UWB systems in multipath channels. The proposed noncoherent TSS-LS employing simple energy window banks utilizes two different thresholds and search windows to achieve fast acquisition. Furthermore, the linear search is adopted for the second step in the proposed scheme to correctly find the starting point in the range of effective delay spread of the multipath channels, and to obtain reliable BER (Bit Error Rate) performance of the noncoherent UWB systems. Simulation results show that the proposed TSS-LS can achieve significant reduction of the required mean acquisition time as compared to general search schemes. In addition, the proposed scheme achieves quite good BER performance, which is favorably comparable to the case of ideal perfect timing.

• Journal of the Korean Magnetics Society
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• v.26 no.3
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• pp.105-114
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• 2016

In this study, For assessment of triangular fibrocartilage complex (TFCC) injury, we acquired images by fat suppressed 3D fast spoiled gradient recalled T1 and fat suppressed Isotropic 3D fast spin echo T1 techniques. For quantitative evaluation, measured signal to noise ratio and contrast to noise ratio and verified statistical significance between two imaging techniques by Mann-Whitney U verification. And for qualitative evaluation, marked 4-grade scoring (0: non diagnostic, 1: poor, 2: adequate, 3: good) on shape of TFCC, artifacts by partial volumes, description of the lesions by two radiologist, verified coincidence between 2 observer using Kappa-value verification. We used 3.0 Tesla MR equipment and 8-channel RF coil for imaging acquisition. As quantitative evaluation results, signal to noise ratio and contrast to noise ratio value of Isotropic 3D fast spin echo T1 technique is higher in every image sections, also between two imaging techniques by Mann-Whitney U verification was statistically significant (p < 0.05). As qualitative results, observer 1, 2 marked a higher grade on Isotropic 3D FSE T1 technique, coincidence verification of evaluation results between two observers by Kappa-value verification was statistically significant (p < 0.05). As a result, during MRI examination on TFCC injury, fat suppressed Isotropic 3D fast spin echo T1 technique is considered offering more useful information about abnormal lesion of TFCC.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.351-354
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• 2002

The F!T tube is a new type of CRT without a shadow mask. Correct color reproduction is performed by an electronic system that measures the landing positions of the electron beams and corrects through a dedicated deflection system. This paper describes in detail the position sensor and some of the electronics needed to build a functional control system. The principle has been shown in single- and triple-beam 17" and 32" tubes, of which results are included.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2271-2281
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• 1998

The wordlength optimization for the analog-to-digital converter in DS-CDMA receivers is very important for the efficient implementation of front-end digital demodulator blocks. Wideband CDMA systems reqire a very fast acquisition time, thus they prefer the matched filter base dreceiver architecture.However, the matched filter should san very long chips, and as a results, requires a large number of gates and a high-power consumption. In this paper, the quantization effects on the acquisition performance of the matched filter is analyzed stochastically. The quantization is modeled as a series of saturation and digitization procedures, because the distortion due to the saturation is signal dependent and causes very different effects when compared with that of the, random, digitization noise. Numerical results are obtained to show the optimum saturaton limit of the quantizer for a given wordlength. This analysis can give a guide to low-cost and low-powr digital implementations and assurance of the system performance without intensive simulations.