• Archives of Plastic Surgery
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• v.35 no.5
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• pp.495-500
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• 2008

Purpose: Adequate tissue oxygenation is considered as an essential factor for wound healing. In the non-diabetic population, an uncompromised macrocirculation generally leads to adequate tissue oxygenation. On the contrary, the macrocirculation in diabetic patients may not correlate with tissue oxygenation because of structural changes in the capillary basement membrane. Nevertheless, many medical professionals in Korea rely on macrocirculation evaluation when predicting wound healing potential of the diabetic ulcers. The purpose of this study is to compare reliability of two common macrocirculation assessment methods, Doppler probing and CT angiography, on tissue oxygenation in diabetic foot patients. Methods: Doppler and CT angiography scores were given according to the patency of the anterior and posterior tibial arteries. Tissue oxygenation was measured by transcutaneous partial oxygen tension($TcpO_2$). Doppler and CT angiography scores were statistically analyzed against $TcpO_2$ values. Sixty-eight diabetic foot ulcer patients were included in this study. Results: The test was carried out on Doppler score and $TcpO_2$ variables displayed a p-value of 0.0202, and concluded that the two variables were statistically dependent. The test used to determine for linear trends between Doppler scores and $TcpO_2$ variables displayed a p-value of 0.0149, displaying statistical linear trend between the two variables. On the contrary, the tests between CT angiography scores and $TcpO_2$ variables showed p-values of 0.1242 and 0.6590, that means no correlation between CT angiography and $TcpO_2$ scores. Conclusion: Doppler probing is more reliable than CT angiography in predicting tissue oxygenation of diabetic foot ulcers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1141-1144
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• 2011

Range walk has been a major problem in achieving correct Doppler processing. This frequently occurs when range variation is severe just like in a bistatic radar or in high speed target scenario. This paper presents a range walk compensated range-Doppler processing algorithm applicable to the bistatic radar. In order for the compensation, a range-domain interpolation is applied for range compressed signal so that Doppler processing is performed along the evenly time-spaced range bins that contain target returns. Under a bistatic radar scenario, the proposed algorithm including a range domain pulse compression is mathematically described. Finally, the validity of the algorithm is demonstrated by simulation results showing the superiority of a SCDP(Squint Cross-range Doppler Processing) over an uncompensated Doppler processing.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.2
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• pp.129-138
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• 2017

This paper has been shown for the extraction of Doppler signature from the radar signal for an air-breathing targets tracked in the ground radar. For the extractions, a Doppler resolution is confirmed from mathematical modeling of PT(pulse train) waveform. Doppler signatures of air-breathing target are varied to radar aspect angle of engine and are determined from physical parameter of jet engine. To confirm such Doppler signatures, the radar signal reflected from the air-breathing target is obtained by our radar signal storage. After this extraction, radar aspect angle of engine has estimated from tracking information. Relative differences of Doppler signatures to radar aspect angle of engine is verified from these results and Doppler profiles for radar target identification appliance are presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1790-1795
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• 2013

The current velocity and turbulence information in each range cell can be obtained from the first and second Doppler spectrum moment estimates. However, the very widely used correlation method often called as the pulse-pair method has the inherent restrictions under the highly turbulent conditions since it does not satisfy the assumptions that the return Doppler spectrum should be symmetric and have a single peak value. Therefore, in this paper, the quality of pulse-pair estimates were compared with that of FFT estimates for problem analysis using various shapes of simulated Doppler spectra. It can be known that the pulse-pair method often yields meaningless results if the received signals are severely biased or multi-peak Doppler spectra in the Doppler frequency domain.

• Journal of the Korean Institute of Navigation
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• v.5 no.2
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• pp.1-39
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• 1981

A doppler log is the typical device which can measure the ship's speed over the ground directly, by means of doppler effect of the underwater ultrasonic wave, which involves the error due to the sea bottom inclination, the trim and the incorrect transducer installation etc. The present doppler log adopts a single transducer, faced in the direction of themain beam, and therefore it is unable to correct the beam direction to eliminate the above mentioned error. Moreover, the frequencyis also limitted in a comparatively high range for getting a sharp beam with single transducer, and the speed over the ground can not be detectable at the deep sea, for an instance, over 200 meters. This paper describes a theoretical consideration for the doppler log error and an analysis by a computer on the observed speed data by a full size model ship. The result is verified that the most of doppler log error is caused by the ultrasonic beam angle of transducer. To eliminate the doppler log error due to the incorrect transducer installation and also to sharpen the beam for lower frequency range to expand measurable sea depth, this paper proposes a method of controlling the directivity adopting a linear transducer array and of controlling the directivity by the control of exciting current, and investigates by the computer simulation and make experiment with magnetostrictive ferrite transducer of 28, 50 and 75KHz. The experimental results are shown well coincide with the measured ones, and they are revealed that in case where the transducer interval is greater than 1 wavelength, the effective control of the beam direction is hardly performed with keeping adequate beam width and side lobe level. It is concluded that 6-elements array with inter element space of a half wavelength can make comparatively sharp beam and low side lobe level. The results obtained here will contribute very much to the improvement of the performance of doppler log.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.138-138
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• 2006

• Journal of Biomedical Engineering Research
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• v.16 no.3
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• pp.279-288
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• 1995

Ultrasonic Doppler systems for the purpose of estimating blood flow velocity, blood flow volume, and flow imaging are commonly used due to advantages of non-invasive and real time observation. Specially, the technical developments of color flow mapping (2-D Doppler) systems have made a relatively rapid progress. However, the 2-D Doppler systems have several problems, such as the range ambiguity, low signal to noise ratio, and slow frame rate. The slow frame rate problem is resolved by using the spatial average which is a method to acquire more data samples for mean frequency estimation. In this paper, spatial average method using the 2nd order sampling instead of quadrature sampling is proposed. The experimental results show that the proposed methods have good performance and easy application to the color flow mapping system.

• Annals of Clinical Neurophysiology
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• v.1 no.1
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• pp.60-63
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• 1999

Transcranial Doppler(TCD) is an important diagnostic tool for evaluating the patients with stroke. It has some advantages and unique role when compared with other neuroimaging modalities. Recent development of transcranial color-coded Doppler(TCD) improves the limitation and pitfalls of TCD. The current indications of TCD are as follows: 1. Screening and evaluation of the intracranial major vessels 2. early detection and follow-up of vasospasm due to SAH 3. emboli detection (high-imtensity transient signals, HITs) 4. dignosis and follow-up of subclavian steal 5. evaluation of intracranial collaterals when the extracranial ICA has severe stenosis or occlusion 6. evaluation of cerebral perfusion pressure (intracranial pressure) 7. evaluation of arteriovenous malformation 8. diagnosis and follow-up of arterial dissenction 9. diagnosis and follow-up of venous sinus thrombosis (experimental).

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.317-324
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• 2008

This paper presents an optical doppler tomography(ODT) system using a speaker as a method to achieve depth measurement in a flowing sample. The use of the speaker provides easy implementation with a low cost. The nonlinear characteristics of the speaker has hindered its adaptation because it produces inconsistent fringe frequencies at different depths. This paper reports an adaptive algorithm to compensate the nonlinear characteristics, and could, resultantly, acquire the Doppler frequency shift caused by the sample. The experiment utilizes a flowing scattering particle solution in a capillary tube at a certain flow rate. The Doppler frequency profile over the lumen was calculated by using spectrogram method. and we obtained the velocity image of the sample.

• Journal of Biomedical Engineering Research
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• v.38 no.5
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• pp.264-270
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• 2017

A Doppler radar sensor was applied to detect respirations and heartbeats of persons who were lying on a bed. This study is preliminary study aiming at non-contact and non-intrusive respiration and heart rate monitoring during sleep in daily life. For the experiments, 10GHz Doppler radar with patch-type antenna was used and installed on the upper right and the distance between the body and the antenna was 1 m. The results show that each signal of respiration and heartbeat is observed in each frequency band however the frequency band and the waveform vary according to the subjects and the posture. The results show that the heartbeats can be detected with the peak detection in some frequency band. This study shows the feasibility of applying the Doppler radar to detection of heartbeat and respiration during sleep and further studies about heartbeat detection algorithm are required.