• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.3
• /
• pp.390-394
• /
• 2003

It is very important to simulate various mobile communication channels for the reliable system design and performance tests. Therefore, a new method is proposed in this paper to improve the conventional one for the purpose of the efficient channel simulation having various characteristics. A newly proposed method can simulate any narrow band channel very efficiently from the given Doppler power spectrum model. Also, it has many simulation advantages considering the variety of wireless channel conditions since parameters related with channel characteristics, such as a signal power, signal to noise ratio, direct signal power ratio, etc., can be easily changed according to various propagation environments to be tested.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.156-159
• /
• 2009

Speckle noise reduction for 3D power doppler ventricle coherent image for restoration and enhancement using wavelet packet transform with separated thresholding is presented. Wavelet Packet Transform divide into low frequency component image to high frequency component image to be multi-resolved. speckle noise is located on high frequency component in multiresolution image mainly. A ventricle image is transformed and inversed with separated threshold function from low to high resolved images for restoration to be utilize visualization for ventricle diagnosis. The experimental result shows that the proposed method has better performance in comparison with the conventional method.

• Journal of electromagnetic engineering and science
• /
• v.12 no.4
• /
• pp.234-239
• /
• 2012

This paper presents a compact K-band Doppler radar sensor for human vital signal detection that uses a radar configuration with only single coupler. The proposed radar front-end configuration can reduce the chip size and the additional RF power loss. The radar front-end IC is composed of a Lange coupler, VCO, and single balanced mixer. The oscillation frequency of the VCO is from 27.3 to 27.8 GHz. The phase noise of the VCO is -91.2 dBc/Hz at a 1 MHz offset frequency, and the output power is -4.8 dBm. The conversion gain of the mixer is about 11 dB. The chip size is $0.89{\times}1.47mm^2$. The compact Ka-band Doppler radar system was developed in order to demonstrate remote human vital signal detection. The radar system consists of a Ka-band Doppler radar module with a $2{\times}2$ patch array antenna, baseband signal conditioning block, DAQ system, and signal processing program. The front-end module size is $2.5{\times}2.5cm^2$. The proposed radar sensor can properly capture a human heartbeat and respiration rate at the distance of 50 cm.

• Journal of Digital Convergence
• /
• v.13 no.9
• /
• pp.251-257
• /
• 2015

Recently, techniques for detecting the movement of the object of energy saving, impact prevention, such as automatic door opening and closing has been applied to various fields. Doppler sensor does not receive a large impact on the environment, such as conventional infrared ray sensor, a problem with an ultrasonic sensor as a sensor which can compensate the temperature, noise, dust and so on. In this paper, when the object to be detected, the LED lamp is turned on 24 hours a Doppler sensor ON, if not switch to the OFF state, the illumination of the LED lamp has been developed for controlling the two-stage converter. Doppler sensor developed by applying the converter module and the power-saving control section leader and demonstrated the power savings.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.5
• /
• pp.460-470
• /
• 2009

In this paper, we described the implementation of the X-Band continuous-wave doppler radar for muzzle velocity measurement. The radar is consisted of microwave transceiver, signal processor, power board, and the measuring program was developed for the operating and field test. The operating frequency of doppler radar is able to set ${\pm}3\;MHz$ with 5 channel from the center frequency, and the output power is 25 dBm. The minimum receiving power is -117 dBm. The radar would obtain the doppler frequency from the artillery, and calculate accurate velocity point and then estimate muzzle velocity. The performance test for this radar was done with 155 mm at barrel and tripod mounted, and also compared the performance with the reference radar. As a result, the performance of the our new radar is equal with the reference one.

• Journal of Satellite, Information and Communications
• /
• v.10 no.2
• /
• pp.60-69
• /
• 2015

A new and effective Doppler effects compensation method based on constellation estimation as well as an average power saving strategy by modified modulation scheme utilizing zero point constellation are presented with theoretical analysis and relevant simulations. The suggested schemes are proved to be very effective for satellite OFDM signals relayed by power limiting transponder for the mobile terminal on high speed vehicles.

• Journal of Satellite, Information and Communications
• /
• v.2 no.1
• /
• pp.7-13
• /
• 2007

A new and effective Doppler effects compensation method based on constellation estimation as well as an average power saving strategy by modified modulation scheme utilizing zero point constellation are presented with theoretical analysis and relevant simulations. The suggested schemes are proved to be very effective for satellite OFDM signals relayed by power limiting transponder for the mobile terminal on high speed vehicles.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.6
• /
• pp.48-55
• /
• 2009

The feedback interference channels are those made through the multipaths that are built by moving and stationary objects around transmit and receive antennas mounted at the same point. This paper describes the method to measure the feedback interference channels in the rural regions and sides of highways and the analysis on channel characteristic parameters. Using the measured samples, we estimated scattering functions, delay power spectra, and Doppler power spectra, and we analyzed the channels using eight parameters including coherence bandwidth, coherence time, maximum excess delay, average excess delay, rms delay spread, Doppler shift, Doppler spread, and spread factor, and delay and Doppler cumulative distributions. Even though many observations are made, note that the feedback signals of high Doppler frequencies and large energy are observed in the sides of highways due to high speed vehicles while low Doppler frequencies occurred in the rural region due to rare traffic.

• Journal of Veterinary Science
• /
• v.21 no.1
• /
• pp.10.1-10.12
• /
• 2020

Blood perfusion of skeletal muscle and callus was evaluated using contrast-enhanced ultrasonography (CEUS) in a canine osteotomy model to determine the applicability of CEUS in the assessment of neovascularization during fracture healing and to compare the vascular signals on CEUS between external skeletal fixation and cast-applied dogs. In 6 Beagle dogs, a simple transverse osteotomy was performed at the left tibial shaft and external skeletal fixation (n = 3) or a cast (n = 3) was applied. Radiography, power Doppler ultrasonography (power Doppler), and CEUS were performed until complete union was achieved. On CEUS, vascular changes were quantitatively evaluated by measuring peak intensity (PI) and time to PI in the soft tissue and callus and by counting the vascular signals. Vascular signals from the soft tissue were detected on power Doppler and CEUS on day 2. Significantly more vascular signals were detected by CEUS than by power Doppler. On CEUS, PI in the surrounding soft tissue was markedly increased after the fracture line appeared indistinctively changed on radiography in all dogs. In the cast-applied dogs, vascular signals from the periosteal and endosteal callus were detected on CEUS before mineralized callus was observed on radiography. CEUS was useful in assessing the vascularity of soft tissue and callus, particularly in indirect fracture healing, and provided indications of a normally healing fracture.

• The Journal of the Acoustical Society of Korea
• /
• v.27 no.2
• /
• pp.80-86
• /
• 2008

Breast ultrasound has many advantages over mammography but suffers from a shortcoming of being not suitable in detecting microcalcification. We studied on a method based on acoustic resonance and power Doppler to detect calcification of breast tissue using a typical 7.5 MHz linear probe used in breast ultrasound examination. We first constructed a breast tissue phantom made of gelatin and then observed calcified legions as external vibrations varied. Calcification injected to the breast tissue phantom being resonated different from the surrounding medium, and its acoustic resonance driven by external vibrations was visualized by differences for color brightness and area in ROI of power doppler. In low frequency regions, the acoustic resonance almost not appeared and showed a plateau in $300{\sim}600\;Hz$ and the color vanished as the frequency further increased.