• Korean Journal of Optics and Photonics
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• v.8 no.6
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• pp.482-485
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• 1997

A new laser Doppler velocimeter employing a $CO_2$laser has been developed by using its optogalvanic effect. A change in the electric impedance of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, was employed to detect the Doppler frequency shift. A Doppler frequency shift as much as 60 KHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.2
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• pp.75-81
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• 2009

In this paper, Microwave doppler radar sensor operated in 10.525GHz is designed by dielectric resonant oscillator. According to doppler effects, a characteristic of Microwave sensor with FMCW was analyzed. The qualities of objects velocity and distance between object and microwave sensor by sensor output frequency difference was measured. As a result of Microwave doppler radar sensor, the prototype sensor is available for indoor burglar alarms and other application through FMCW signal.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.61-69
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• 2006

Position determination accuracy is strongly depending on how much precisely and frequently satellite receiver measures transmitted signals from terminals on target animals when Doppler effect is applied for position determination. ARGOS satellite system has shown relatively high position determination accuracy by operating multiple satellites, which enable operator to get more Doppler shift data from terminals. In case of animal tracking mission with single satellite, however, it is difficult for the satellite receiver to receive transmitted signals from terminals frequently during short period that satellite passes over ground terminals. This is one of the main sources to decrease position accuracy on target animals. In this paper, the Doppler rate estimation is implemented to increase the number of Doppler shift data received by single satellite. It is proved that the relatively high position determination accuracy with increased number of estimated data can be obtained. We also suggest that the Doppler rate estimation is applicable for position determination system with single satellite.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.250-254
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• 2000

We have constructed laser Doppler velocimetry system using self-mixing effect with a semiconductor laser. This technology is based on the frequency mixing phenomena which occurs when light scattered back from the moving object into the laser cavity interferes with light inside the laser. We have compared the value of Doppler shifted frequency with the velocity variation of the wheel. Frequency dependence on the angle between the moving direction of rotating aluminum wheel and the incident beam also have been proved. As an illustration of the performance of the velocimeter, velocity measurements of a rotating disk are described. Doppler signal shows a good linear relationship with velocity of rotating disk.

• Nuclear industry
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• v.20 no.6 s.208
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• pp.31-44
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• 2000

본 연구에서 액체금속로의 노심용융(core meltdown)으로 인한 초 즉발 임계(super-prompt critical)의 출력 폭주 사고시, 노심의 반응도 및 열수력 특성 변화와 에너지 방출량등을 계산하기 위하여, Bethe-Tait 방버론을 수정, 보완한 분석 모델이 개발되었다. 주요 보완 내용으로서는, 금속 연료 노심의 단상 액체 영역에서의 선형의(Linear) threshold 형태의 상태 방정식뿐만 아니라 포화 증기(saturated fuel vapor) 영역에서의 상태 방정식이 개발되었고, 이에 따른 노심 붕괴 반응도(disassembly reactivity)의 분석 모델이 개발되었다. 또한 도플러 반응도 효과를 고려하기 위한 분석모델도 아울러 개발되었다. 상기 보완 모델을 실행할 수 있는 수치 해석 프로그램이 개발되었고, 이를 활용하여 KALIMER에서 HCDA가 발생하였을 경우 노심에서의 에너지 방출량 계산이 수행되었다. 분석결과 도플러 효과와 포화 증기 영역에서의 압력 증가 및 노심팽창의 중요성이 확인되었다. 도플러 효과가 고려되지 않을 경우 HCDA는 분석된 모든 반응도 삽입률에 대하여 폭발적인 에너지 방출과 함께 사고가 종결되는 것으로 평가되었다. 그러나 도플러 상수가 최적 평가치인 -0.002인 경우 50$/s이하의 반응도 삽입률에서는 노심은 비등점(0.8KJ/g)에 도달치 않았으며, 설계 기준 사고인 100$/s의 경우에도 노심은 포화 증기 영역에 머물고 압력이 급격히 증가하는 단상(single phase)액체 영역의 threshold 값에 미치지 않기 때문에 사고는 핵연료 증기(vapor)의 점진적인 분산과 함께 종결되는 것으로 분석되며, 총 에너지 발생량은 약 1,800MJ로서 기계적 손상 에너지로 전환되는 분율을 고려할 때 KALIMER 원자로 용기의 구조 설계 기준치에 비해 상당한 여유도를 갖는 것으로 평가되었다.

• Journal of Biomedical Engineering Research
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• v.7 no.2
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• pp.139-146
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• 1986

Pulsed ultrasonic Doppler system is a useful diagnostic instrument to measure blood-flow-velocity, velocity profile, and volume-blood-flow. This system is more powerful compare with 2-dimensional B-scan tissue image. A system has been deve- loped and ii being evaluated using TMS 32010 DSP. We use this DSP for the purpose of real-time spectrum analyzer to obtain spectrogram in singlegate pulsed Doppler system and for the serial comb filter to cancel clutter and zero crossing counter to estimate Doppler mean frequency in multigate pulsed Doppler system. The Doppler shift of the backscattered signals is sensed in a phase detector. This Doppler signal corresponds to the mean velocity over a some region in space defined by the ultrasonic beam dimensions, transmitted pulse duration, and transducer ban(iwidth. Multi- gate pulsed Doppler system enable the transcutaneous and simultaneous assessment of the velocities in a number of adjacent sample volumes as a continuous function of time. A multigate pulsed Doppler system processing the information originating from presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.523-526
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• 2017

In modern recently technology, 3D-Audio is used to enhance immersion in Virtual Reality. This includes interest of people about VR and AR, which related to the field of computer graphics. In fact, a lot of research has been carried out in recent years into a 3D sound field. However, the existing 3D generator device used for virtual reality does not contain Doppler effect occurred by the sound comes to or leave from a listener, while an angle from the listener and the altitude of the source sound are applied. Therefore, this paper present 3D real sound utilizing Doppler effect with spatial-rotation-speaker. We map the source sound in 3D-space into a real space where a user stays and present 3D real sound by manipulating with rotation angle, phase difference, sound output volume of the sound in 3D-space, according to the location of a virtual source sound. Utilizing both natural Doppler effect of rotating sound that is occurring by spatial-rotation-speaker and artificial Doppler effect generated by frequency-modulation of sound quality could improving the virtual reality for sound condition for perspective listening.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.241-242
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• 2009

도플러 효과를 이용해 피부의 혈류 속도 분포를 측정하였다. 고속 CMOS 이미지 센서를 사용하여 $256{\times}256$ 픽셀의 크기를 갖는 혈류 속도 영상을 측정하였다. 많은 의학 치료 분야에서 혈류 흐름에 대한 영상, 특히 모세혈관에서의 혈류 흐름에 대한 영상을 필요로 한다. 레이저 도플러 기술은 물체의 속도를 물체에 접촉하지 않고 측정할 수 있는 대표적인 기술로, 레이저 광의 코헤런트한 특성과 비접촉성 특성은 인체 피부의 혈류 속도를 측정하는데 좋은 특성을 제공한다.

• Journal of radiological science and technology
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• v.38 no.1
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• pp.7-15
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• 2015

A ultrasonic probe is very important in medical ultrasonic image, but the frequency of probe defects are often. Therefore practical tools for probe based ultrasonic QA should be developed. Advanced research on the effects of the probe defects on the quality of ultrasonic images is required. This study has investigated the effects of the defects in the probe elements influence Doppler images in the medical ultrasonic scanners. Especially the defects in a set of adjacent elements(SAE) electrically disconnected influence Doppler images were tested. The results show Doppler brightness and velocity became rapidly reduced as the defected elements is located centrally, as the defected elements is activated. The more the defected elements increased, the more Doppler brightness and velocity increased. As a set of the element disconnected moved, it appeared Doppler velocity starting to decrease and then was followed by brightness. The strength is not consistent with the velocity in the number and location of the defected elements. The defects in the probe elements influence Doppler velocity when the defected elements got out of the elements activated at Doppler mode.

• The Journal of the Acoustical Society of Korea
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• v.35 no.5
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• pp.331-339
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• 2016

This paper suggests an estimation method of the source signal and the channel impulse response (CIR) using ray-based blind deconvolution (RBD) in the underwater acoustic channel environment where Doppler effect exists by the relative motion between source and receiver. It is difficult to estimate the CIR on Doppler effect by the matched filter with a highly Doppler-sensitive waveform such as the m-sequence signal because Doppler shift can severely degrade the correlation between the received signal corrupted by Doppler effect and the original source signal. In this study, the Doppler-shifted source-signal's phase is estimated using the RBD, and the received signal is compensated by it to obtain the Doppler-corrected CIR. It is verified that using the matched filter with the received signal from the experimental data fails to estimate the CIR while the obtained CIR by the suggested method has the similarity to the propagation path of the ray model. Also, the results show that the reconstructed source signal using the RBD has the better Doppler shift compensation than the Doppler-shifted source signal derived from scattering function.