• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.956-957
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• 2014

유속측정 레이다에서는 수신되는 도플러 신호의 스펙트럼을 추정함으로서 속도정보를 추출하게 된다. 그러나 저 유속인 경우 상대적으로 도플러 주파수 대역이 매우 저주파 영역에 나타나게 되며 이로 인하여 신호의 위상잡음이나 배경 클러터 등에 의한 영향을 심하게 받게 된다. 따라서 이러한 경우의 추정치 개선을 위한 방법을 분석하였다.

• ETRI Journal
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• 제38권4호
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• pp.634-644
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• 2016

Channel-based radio-frequency fingerprinting such as a channel impulse response (CIR), channel transfer function (CTF), and frequency coherence function (FCF) have been recently proposed to improve the accuracy at the physical layer; however, their empirical performance, advantages, and limitations have not been well reported. This paper provides a comprehensive empirical performance evaluation of RF location fingerprinting, focusing on a comparison of received-signal strength, CIR-, CTF-, and FCF-based fingerprinting using the weighted k-nearest neighbor pattern recognition technique. Frequency domain channel measurements in the IEEE 802.11 band taken on a university campus were used to evaluate the accuracy of the fingerprinting types and their robustness to human-induced motion perturbations of the channel. The localization performance was analyzed, and the results are described using the spatial and temporal radio propagation characteristics. In particular, we introduce the coherence region to explain the spatial properties and investigate the impact of the Doppler spread in time-varying channels on the time coherence of RF fingerprint structures.

• 천문학논총
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• 제30권2호
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• pp.327-330
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• 2015

Cosmology considers the Hubble redshift of galaxy light by the Doppler effect as proof the Universe has been expanding since the Big Bang. However, cosmic dust that permeates the Universe also redshifts galaxy light that if not corrected over-predicts the velocities of all astronomical measurements inferred by the Doppler effect. Hubble redshifts corrected for cosmic dust suggest the Universe may not be expanding, the consequence of which may allow the outstanding problems in cosmology to possibly be resolved by Newtonian mechanics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.148-148
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• 2000

In this paper the IMM(Interacting Multiple model) algorithm using the MGEKF(Modified Gain Extended Kalman Filter) which modes are variances of the process noises is proposed to enhance the performance of maneuvering target tracking with bearing and frequency measurements. The state are composed of relative position, relative velocity, relative acceleration and doppler frequency. The mode probability is calculated from the bearing and frequency measurements. The proposed algorithm is tested a series of computer simulation runs.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 추계학술발표회논문집(1)
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• pp.254-259
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• 1996

Phase Doppler particle analyze. (PDPA) is a instrument which can be used to obtain simultaneous size and velocity measurements in a multiphase flow. In this study, the size of the water droplets entrained from a bubbling surface of a stagnant liquid column is measured by PDPA with a specially designed transmitter of long focal length and large beam diameter. The test section tube is made of acryle with 18 mm I.D. and 900 mm length. The experimental data are obtained for the air superficial velocity between 0.7 m/s to 3.4 m/s at atmospheric pressure. The experimental results show that there exists large difference in the entrainment mechanism between the churn-turbulent flow and annular flow. Through the present study, the phase Doppler analyzer system is shown to be successfully applied to measure particle sizes larger than $2,000\mu\textrm{m}$ if a transmitter of long focal length is utilized.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.348-351
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• 2006

Initial results of processing data from an experiment performed in November, 2005 are given. A microwave Doppler radar with a knife-like beam ($1.5^0$ - $24.5^0$) was installed on a helicopter. Measurements were made during a flight above the Gorky water storage basin. Power and Doppler spectra of the radar reflected signal were analyzed. The processing has shown that the algorithm developed for the retrieval of the slopes of rough water surface enables one to determine the direction of wave propagation and retrieve the variance of the wave slopes.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.853-856
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• 2007

기상 레이다에서의 반사 신호는 비, 구름 등에 의하여 산란되는 전자파 신호로서 이러한 도플러 신호를 분석함으로서 여러 가지 특징적인 기상정보를 추출하게 된다. 그런데 이러한 기상정보를 정확히 추출하기 위해서는 지표면 클러터 및 레이다에서의 도플러 기상정보들이 어떻게 나타나는지 그 특징을 잘 파악하여야 할 것이다. 따라서 본 논문에서는 기존의 대칭형 도플러 스펙트럼 모델을 개선할 수 있는 비대칭 도플러 모델을 제안하였다. 제안된 기상 도플러 스펙트럼 모텔은 기상조건, 운영환경 및 시스템 특성에 따라 다양하게 모의될 수 있으므로 기상 레이다 정보추출의 신뢰성 검증 및 성능향상에 많은 도움이 될 수 있을 것이다.

• 한국임상수의학회지
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• 제33권6호
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• pp.321-324
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• 2016

The present study compared two indirect blood pressure methods at thoracic limb, pelvic limb, and coccygeal sites. For measurement of blood pressure, 48 client-owned dogs in a clinical setting were used. When comparing the results obtained by doppler and oscillometric methods, there were significant differences in blood pressure of the thoracic and pelvic limbs. The Doppler machine produced significantly higher blood pressure value than oscillometry measured at thoracic and pelvic limbs. The difference in blood pressure between the two methods was not significant when measured in the tail. Comparison of blood pressure measured at three different sites by doppler, blood pressure measured at pelvic limb was higher than at thoracic limb and tail. In case of oscillometry, there were no significant differences between the three sites. The results of this study indicate that mechanical and positional differences were existed in blood pressure measurements at the canine thoracic limb, pelvic limb and tail.

• Wind and Structures
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• 제24권2호
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• pp.185-204
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• 2017

High-resolution wind measurements at 2.25 m in height were used to investigate the mean and turbulence properties of an extreme thunderstorm wind event in West Texas. These data were combined with single Doppler scans from the Texas Tech University Ka-band mobile Doppler radars systems (TTUKa) to provide meteorological context over the surface measurement stations for portions of the outflow. Several features characteristic of a severe wind event were noted in the radar data, including a bowing portion of the thunderstorm complex and a small circulation on the leading edge. These features were reflected in the surface wind time histories and provided natural separation between various regions of the outflow. These features also contributed to the peak 1-s gust at all measurement stations. The turbulence characteristics of each outflow region were also investigated and compared. Reduced values of running turbulence intensity and elevated values of longitudinal integral scales were noted during the period of peak wind speed. Larger scales of turbulence within the outflow were also suggested via spectral analysis.

• 한국임상수의학회지
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• 제34권4호
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• pp.249-254
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• 2017

The cutaneous microcirculation plays a role in various physiological processes and pathological conditions. Two non-invasive methods were used in this study to obtain reference values for cutaneous microcirculation in intact male beagles. Twenty intact male beagles were used. The experimental environments were standardized. Laser Doppler flowmetry was used to measure cutaneous blood flow, and an infrared thermometer was used to measure cutaneous temperature. The blood flow and temperature were measured from the right side of the subjects at 20 cutaneous sites. Based on the laser Doppler flowmetry, the region with the highest blood flow was the periocular region that with the lowest was the forelimb foot pad. In addition, the standard deviation of the chest wall was the highest while that of the periocular region was the lowest. For skin temperature, the inguinal region had the highest mean skin temperature and the forelimb foot pad had the lowest. The correlation coefficient between the two methods was 0.72. Similar to a previous study, the values derived from repeated measurements at the 20 regions are reproducible and can contribute to research. Compared to the results of a previous study, the temperatures of the two smallest skin regions were the same; however, no specific trend was observed. The correlation coefficient between the two methods was significantly comparable, and this good correlation can reduce their limitations and variables complementarily. In addition to possible use in human studies, accumulated resources on measurements of skin blood flow in the future will potentiate its use in the veterinary medicine field.