• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1727-1730
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• 2016

Magnetic resonance imaging has a potential to produce clear anatomical as well as functional images of human body. However, the ability to diagnose is limited by signal to noise ratio (SNR) and the resolution of current medical systems. To remove the challenges prevalent due to the use of high field scanners, dedicated radio frequency coils are used. Transverse electromagnetic coils have an advantage of providing homogeneous magnetic field throughout the region but with low signal to noise ratio while surface coils have an advantage of providing higher signal to noise ratio but with low homogeneity. This research combines both the advantage into one by utilizing transmit only transverse electromagnetic radio frequency coils (8 channel) along with receive only surface coils (by varying the number) for better imaging of brain. A 7 Tesla 32-channel close fitting helmet shaped phased-array surface coils along with the combination of 8 channel transmit only transverse electromagnetic coils provided good homogeneity as well as significant SNR improvements throughout the human brain.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2071-2077
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• 2010

Interface modules design between image sensor and external components are designed by FPGA (Field Programmable Gate Array) in this paper. Generally speaking, to satisfy synchronization for the poor quality data in image, SRAM is needed. To receive synchronization signal and image signal data with pixel dimension, the proposed interface logic technique is implemented. From the proposed technique, we can obtain more clear screen by implementing with pixel dimension. Operating frequency of image sensor and that of TFT-LCD are 50MHz and 6.5MHz, respectively. Most of control logic functions are embedded in FPGA. The designed logic gate counter has 33,216 and is designed by Quartus II.

• Journal of the Korea Society of Computer and Information
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• v.7 no.4
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• pp.115-120
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• 2002

This paper presents the implementation of IS-95 CDMA signal processor, baseband and Intermediate Frequency(IF) digital converter using Field Programmable Gate Array(FPGA) and ADC/DAC and frequency up/down converter IS-95 CDMA channel processor is generated the pilot channel signal with short PN code and Walsh-code generator. The digital If is composed of FPGA. digital transmit/receive signal processor and high speed analog-to-digital converter(ADC) and digital-to-analog converter(DAC). The frequency up/down converter consisted of filter, mixer, digital attenuator and PLL is analog conversion between intermediate frequency(IF) and baseband. This implemented system can be deployed in the IS-95 CDMA base station device etc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.827-832
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• 2011

Communication is very important in warfare. Dispatch riders were used in ancient warfare, but communication system is used in modern warfare, as the advancement of communication equipments. In order to weaken enemy military strength, communication jamming signal disrupts enemy communication systems. Tone jamming is one of the common communication jamming techniques. Tone jamming is that several tones are placed in the spectrum for neutralizing the enemy's radio communication receivers. In this paper, we develop multitone jamming signal controlled tone number up to 10 tones and tone interval between tones using DDS(Direct Digital Synthesizer) core and FPGA(Field Programmable Gate Arry) of Xilinx Inc. and show the jamming signal output.

• Korean Journal of Optics and Photonics
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• v.8 no.5
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• pp.372-376
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• 1997

We study the time resolved anti-Stokes Raman spectroscopy with correlated pump and Stokes waves. When only two pump waves with relative delay are incident into a Raman medium, the Stokes waves generated by stimulated Raman scattering couple with the pump waves to generate anti-Stokes signal. Since the correlation between Stokes and the pump waves are not perfect and not quantified yet, we make a simple model fot it and calculate the normalized anti-Stokes signal intensities as a function of time delay. The broadband light regarded as chaotic field.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.571-574
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• 1997

fMRI, functional MRI introduced recently appears based on the gradient echo technique which is sensitive to the field inhomogeneity developed due to the local susceptibility changes of blood oxygenation and deoxygenation. Common to all the gradient echo techniques is that the signal due to the susceptibility effects is generally decreased with increasing inhomogeneity due to the $T2^*$ effect or conventionally known as blood oxygenation level dependent (BOLD) effect. It is, also found that the BOLD sensitivity is also dependent on the imaging modes, namely whether the imaging is in axial, or coronal or sagittal mode as well as the directions of the vessels against the main magnetic field. We have, therefore, launched a systematic study of imaging mode dependent signal change or BOLD sensitivity as well as the signal changes due to the tilting angle of the imaging planes. Study has been made or both TRFGE sequence and CGE sequence to compare the distinctions of the each mode since each technique has different sensitivity against susceptibility effect. Method of computation and both the computer simulations and their corresponding experimental results are presented.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.32-37
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• 2005

We developed a numerical simulator in order to study the Super-RENS/ROM (Super REsolution Near-Field Structure, Read Only Memory) using 3-dimensional FDTD (finite difference time domain) method. The simulation can be performed by three steps. In the first step, we utilized the vector-diffraction theory to calculate the characteristics of incident laser beam from the object-lens to the surface of the disk. At the second step, we fed the calculated result as an input for the main FDTD simulations on the optical layers in the disk structure. After performed the FDTD simulations, we took near-to-far field transformation for the reflected signal, from the surface of the disk to the detector. Finally, we can get reflected signal at the photo-diode. Using this developed simulator, we were able to study about the reading signal from various disk structures as a function of a laser beam position. We calculated reading signals for various pit sizes for Super-ROM structure, and it is found that the simple optical diffraction theory can not explain the reading mechanism of Super-ROM, and more complicated temperature dependent physics must be involved.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.31-38
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• 1990

An antenna gain measurement system using an extrapolation technique is described. The technique is similar to the usual two-antenna method for absolute gain measurement system, but involves the measurement of the received signal as a function of seperation in short distances, and the signal-versus-seperation data is processed in a way that allows an extrapolation of the signal to "infinite" seperation. In this technique it is possible to obtain the near field gain as function of distance by combining the far field gain and a proximity correction factor. The results of gain measurements of standard gain horn antennas and OEG (open ended waveguide) antennas are also presented.

• Transactions of the Society of Information Storage Systems
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• v.2 no.2
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• pp.138-143
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• 2006

We developed a numerical simulator in order to study the Super-RENS/ROM (Super REsolution Near-Field Structure, Read Only Memory) using 3-dimensional FDTD (finite difference time domain) method. The simulation can be performed by three steps. In the first step, we utilized the vector-diffraction theory to calculate the characteristics of incident laser beam from the object-lens to the surface of the disk. At the second step, we fed the calculated result as an input for the main FDTD simulations on the optical layers in the disk structure. After performed the FDTD simulations, we took near-to-far field transformation for the reflected signal, from the surface of the disk to the detector. Finally, we can get reflected signal at the photo-diode. Using this developed simulator, we were able to study about the reading signal from various disk structures as a function of a laser beam position. We calculated reading signals for various pit sizes for Super-ROM structure, and it is found that the simple optical diffraction theory can not explain the reading mechanism of Super-ROM, and more complicated temperature dependent physics must be involved.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.4
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• pp.43-49
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• 2021

A small infrared image homing system is a tracking system that has an infrared image sensor that identifies a target through the day and night infrared image processing of the target on the ground and searches for and detects the target with respect to the main target. This paper describes the development of a board equipped with a high-speed CPU and FPGA (Field Programmable Gate Array) to identify target through real-time image processing by acquiring target information through infrared image. We propose a CPU-FPGA combining architecture for CPU and FPGA selection and video signal processing, and also describe a controller design using FPGA to control infrared sensor.