• Restorative Dentistry and Endodontics
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• v.35 no.6
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• pp.492-496
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• 2010

Coronal discoloration is a common sequela to traumatic injuries. In subluxation cases, although the injury is not strong enough to rupture the apical vessels, discoloration may appear by tearing thin walls or occluding small capillaries. In absence of infection pulpal regeneration can occur, and as a result discoloration may completely or partially subside. But judging pulpal status by coronal discoloration can be dangerous and it may lead to unnecessary treatment. This case presents coronal discoloration and recovery following traumatic injury of maxillary anterior teeth. In diagnosing traumatized teeth routine cold tests or electric pulp tests are known to be unreliable, but with the aid of ultrasound doppler imaging, assessing pulp vitality of traumatized teeth can be more accurate.

• Journal of Digital Convergence
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• v.13 no.9
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• pp.251-257
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• 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 the Acoustical Society of Korea
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• v.27 no.2
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• pp.80-86
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• 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.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.413-419
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• 2001

This study was performed to evaluate the renal hemodynamics using color Doppler ultrasonography in dogs with unilateral experimental hydronephrosis treated with transarterial embolization of the renal artery (TAE-RA). Experimental hydronephrosis was induced by ligation of unilateral ureter in 12 dogs. The mean resistive index (RI) value of kidney was significantly increased at 4, 9, 17 days after ligation of ureter. Unilateral hydronephrosis was established in 12 dogs at 17 days after ligation of ureter. Renal artery embolization was performed using selective catheterization in the hydronephrotic kidney of seven dogs and EKG, $SpO_2$body temperature, pulse, and respiratory rate were within normal ranges during procedures. There were no dogs expired after TAE-RA and no side effects associated with regurgitation of iohexol-ethanol solution. In color Doppler ultrasonographic findings, there was no blood flow into the embolized kidneys treated by TAE-RA, however, blood flow signal was found in contralateral normal kidney of dogs treated with TAE-RA compared to that of normal kidney in normal control group. It is concluded that TAE-RA does not affect the hemodynamics of contralateral normal kidney in dogs with experimental hydronephrosis and color Doppler ultrasonography is simple and non-invasive modality for the monitoring of the revascularization of the renal artery after TAE-RA.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.751-759
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• 2023

Breast ultrasonography is difficult to image in fatty breasts and to find micro-calcification, but the discovery of micro-calcification is very important for breast cancer screening. Among the color Doppler artifact of ultrasound, twinkle artifact mainly occur on strong reflectors such as stones or calcification in images, and evaluation methods using them are clinically being used. In this study, we are conducting experiments on the color Doppler settings of ultrasound equipment, such as repetition frequency, ensemble, persist, wall filtering, smoothing, linear density, and dissociation value, by producing a breast simulation phantom using the largest amount of calcium phosphate among breast implants. The purpose of this study was to improve the contrast of twinkle artifact in breast ultrasound examinations and to maximize their use in clinical practice. As a result, the pulse repetition frequency occurred in the range of 3.6 kHz to 7.2 kHz, and did not occur above 10.5 kHz. For ensembles, twinkle artifact occurred in all sizes of calcification under low conditions, and in threshold settings, the twinkle artifact increased slightly only under 80 to 100 conditions, and did not occur in 1 mm size calcification. Persist, wall filter, smoothing, and line density settings did not have much meaning in the setting variable because conditions did not increase by condition, and pulse repetition frequency, ensemble, and thresholds had the greatest impact on the twinkling artifact image. This study is expected to help examiners select optimal conditions to effectively increase twinkle artifact by adjusting color Doppler settings.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.214-219
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• 2012

초음파전파영상화(UPI) 시스템은 2007년에 첫 논문 발표를 통해 시스템 개발이 보고된 이후 소프트웨어 및 하드웨어적 측면에서 다양한 형태로 발전된 시스템의 개발이 이루어졌다. 본 기고에서는 기본 UPI 시스템, 섬유파트랜스듀서 UPI 시스템, 순수광학시스템으로서 광섬유 센서 UPI 시스템, 완전비접촉 시스템으로서의 공기정압압전센서 UPI 시스템 및 레이저도플러진동계 UPI 시스템, 장거리 UPI 시스템, 옥외 적용성에 필수적인 저온환경 UPI 시스템 등을 소개한다.

• The Journal of the Acoustical Society of Korea
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• v.9 no.3
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• pp.48-55
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• 1990

We analyze the effect of second-order sampling on estimating the mean frequency of the Doppler signal. In order to reduce the sampling frequency of analogue-to-digital converter, it is possible to obtain the Doppler signal by sampling the radio frequency echo signal with the low frequence of $4f_0$/5 or $4f_0$/9 instead of $4f_0$, where $f_0$ is the center frequency of the transmitted signal. The computer simulation and experiments show that if the narrowband signal is transmitted as is usual in the Doppler system, the error of the mean frequency estimates due to the low sampling frequency is negligible.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.472-477
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• 2010

자동유량측정시설은 연속적인 유량자료를 측정하기 위해 운영되는 실시간-무인화 유량측정 시스템이다. 현재 국내 외에서 유량측정을 위해 설치 및 운영되고 있는 자동유량측정시설은 대부분 초음파유속계를 이용하고 있는는데, 초음파유속계는 유속을 측정하는 방식에 따라 크게 도플러방식 초음파유속계(ADVM, Acoustic Doppler Velocity Meter)와 이동시간차방식 초음파유속계(UVM, Ultrasonic Velocity Meter)로 분류된다. 본 연구에서는 각 방식별로 유량산정방법을 개선하기 위해 설치 운영 중인 자동유량측정시설 중 고령교 지점의 ADVM 방식과 여주, 적성 지점의 UVM 방식을 대상으로 측정성과에 대한 문제점을 분석하고 통계적인 방법을 통해 오측유속을 제거하거나 방식별 또는 지점별 특성을 고려하여 적절한 유량산정방법을 적용하였다. 그 결과 3개 지점에 대한 검증유량과의 평균 상대오차율은 모두 10% 이내로 나타났다.

• Journal of Biomedical Engineering Research
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• v.6 no.1
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• pp.47-54
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• 1985

In this paper, clutter in ultrasound pulsed Doppler system is analyzed mathematically. And stationary canceler which reduce the clutter is designed. The operating characteristics of the stationary canceler is investigated in body (in vivo) by audio signal and spectrum analyzer.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.175-182
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• 1995

Despite the simplicity of processing, a conventional autocorrelation function (ACF) method for the precise determination of fetal heart rate (FHR) has many problems. In case of weak or noise corrupted Doppler ultrasound signal, the ACF method is very sensitive to the threshold level and data window length. It is very troublesome to extract FHR when there is a data loss. To overcome these problems, the high resolution pitch detection algorithm was adopted to estimate the FHR. This method is more accurate, robust and reliable than the ACF method. With a lot of calculation, however, it is impossible to process real time FHR estimation. This paper is presented a new FHR estimation algorithm for real time processing and studied the real time FHR monitoring system by high resolution pitch detection algorithm.