• Title/Summary/Keyword: velocity information

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Experimental Study on Heat Transfer with Swirling Flow in a Cylindrical Annuli (원형동심관내 선회유동의 열전달에 대한 실험적 연구)

  • Chang, Tae-Hyun;Kil, Sang-Cheol;Lee, Kwon-Soo
    • Journal of the Korean Society of Visualization
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    • v.8 no.1
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    • pp.53-60
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    • 2010
  • Experimental investigations were conducted to study the characteristics of turbulent swirling flow in an axisymmetric annuli. Swirl angle measurements were performed using a flow visualization technique using smoke and dye liquid for Re=60,00080,000. Using the two-dimensional particle image velocimetry method, we found the time-mean velocity distribution and turbulent intensities in water with swirl for Re=20,000, 30,000, and 40,000 along longitudinal sections. Neutral points occurred for equal axial velocity at y/(R-r)=0.70.75, and the highest axial velocity was recorded near y/(R-r)=0.9. Negative axial velocity was observed near the convex tube along X/(D-d)=3~23. Another experimental study was performed to investigate heat transfer characteristics of turbulent swirling flow in an axisymmetric annuli. Static pressure, and local flow temperature were measured using tangential inlet condition and the friction factors and Nusselt number were calculated for several Reynolds numbers.

Experimental Results of Ship's Maneuvering Test Using GPS

  • Yoo, Yun-Ja;Naknma, Yoshiyasu;Kouguchi, Nobuyoshi;Song, Chae-Uk
    • Journal of Navigation and Port Research
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    • v.33 no.2
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    • pp.99-104
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    • 2009
  • The Kinematic GPS is well known to provide a quite good accuracy of positioning within an level. Although kinematic GPS assures high precision measurement on the basis of an appreciable distance between a reference station and an observational point, it has measurable distance restriction within 20 km from a reference station on land. Therefore, it is necessary to make out a simple and low-cost method to obtain accurate positioning information without distance restriction In this paper, the velocity integration method to get the precise velocity information of a ship is explained. The experimental results of Zig-zag maneuver and Williamson turn as the ship's maneuvering test, and other experimental results of ship's movement during leaving and entering the port with low speed were shown. From the experimental results, ship's course, speed and position are compared with those obtained by kinematic-GPS, velocity integration method and dead reckoning position using Gyro-compass and Doppler-log.

TDOA Based Moving Target Velocity Estimation in Sensor Network (센서네트워크 내에서 TDOA 측정치 기반의 이동 표적 속도 정보 추정)

  • Kim, Yong Hwi;Park, Min Soo;Park, Jin Bae;Yoon, Tae Sung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.3
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    • pp.445-450
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    • 2015
  • In the moving target problem, the velocity information of the moving target is very important as well as the high accuracy position information. To solve this problem, active researches are being conducted recently with combine the Time Difference of Arrival (TDOA) and Frequency Delay of Arrival(FDOA) measurements. However, since the FDOA measurement is utilizing the Doppler effect due to the relative velocity between the target source and the receiver sensor, it may be difficult to use the FDOA measurement if the moving target speed is not sufficiently fast. In this paper, we propose a method for estimating the position and the velocities of the target by using only the TDOA measurements for the low speed moving target in the indoor environment with sensor network. First, the target position and heading angle are obtained from the estimated positions of two attached transmitters on the target. Then, the target angular and linear velocities are also estimated. In addtion, we apply the Instrumental Variable (IV) technique to compensate the estimation error of the estimated target velocity. In simulation, the performance of the proposed algorithm is verified.

Estimation of Velocity and Training Overhead Constraints for Energy Efficient Cooperative Technique in Wireless Sensor Networks (협력통신을 이용하는 무선 센서네트워크에서의 에너지 소비 감소를 위한 속도와 훈련심볼의 오버헤드 임계값 추정)

  • Islam, Mohanmmad Rakibul;Kim, Jin-Sang;Cho, Won-Kyung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.5B
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    • pp.443-448
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    • 2009
  • A boundary value of the velocity of data gathering node (DGN) and a critical value for training overhead beyond which the scheme will not be feasible for a Multiple Input Multiple Output (MIMO) based cooperative communication for energy-limited wireless sensor networks is proposed in this paper. The performance in terms of energy efficiency and delay for a combination of two transmitting and two receiving antennas is analyzed. The results show that a set of critical value of velocity and training overhead pair is present for the long haul communication from the sensors to the data gathering node. Finally a relation between training overhead and velocity is simulated.

Experimental Results of Ship's Maneuvering Test Using GPS

  • Yoo, Yun-Ja;Hou, Dai-Jin;Hamada, Masaaki;Nakama, Yoshiyasu;Kouguchi, Nobuyoshi
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2006.10a
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    • pp.49-55
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    • 2006
  • Kinematic GPS provides quite good accuracy of position in cm level. Though K-GPS assures high precision measurement in cm level on the basis of an appreciable distance between a station and an observational point, but it has measurable distance restriction within 20 km from a reference station on land. So it is necessary to make out a simple and low-cost method to obtain accurate positioning information without distance restriction. In this paper, the velocity integration method to get the precise velocity information of ship is explained. Next two experimental results (Zig-zag maneuvering test and Williamson turn) as the ship's maneuvering test and also the experimental results of leaving and entering port as slow speed ship's movement were shown. In these experimental results, ship's course, speed and position are compared with those obtained by kinematic-GPS, velocity integration method and dead reckoning position using Gyro-compass and Doppler-log.

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A Measurement of Traffic Vehicles Flow by the Ultrasonic Spatial Filtering Method (교통난 계측 I-초음파용 공간필터법에 의하여-)

  • 전승환
    • Journal of the Korean Institute of Navigation
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    • v.20 no.2
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    • pp.51-58
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    • 1996
  • For the smooth flow of traffic vehicles and its effective management, it is necessary to have an exact information on traffic condition, i.e., the volume of traffic, velocity, occupancy and classification of vehicles. In particular, for classification of vehicles, there has been only image processing method using camera, where the method can obtain much information but rather expensive. In this paper, an algorithm for the measurement of velocity and total length of vehicles has been proposed to develop a general traffic management system, which is necessary to discriminate the class of vehicles. In order to realize the proposed algorithm, we have developed an ultrasonic spatial filtering method, which has better performance than that of using the traditional vehicle detector. To have this system to be constructed, we have introduced three sets of ultrasonic devices where each has one transmitter and two receivers which are arranged to obtain the spatial difference of objects. The velocity of vehicles can be measured by analyzing the occurrence time of pulses and their time differences. The total length of vehicles can be given by multiplying velocity with time interval of pulses sequence. To confirm the effectiveness of this measuring system, the experiment by the spatial filtering method using the ultrasonic sensors has been carried out. As the results, it is found that the proposed method can be used as one of measurement tools in the general traffic management system.

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Development of Estimation Method for Velocity Pressure Exposure Coefficient of Buildings Based on Spatial Information (공간정보기반 건축물의 풍속고도분포계수 산정 방법 개발)

  • SEO, Eun-Su;CHOI, Se-Hyu
    • Journal of the Korean Association of Geographic Information Studies
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    • v.20 no.2
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    • pp.32-46
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    • 2017
  • Recent rapid urban expansion and crowding of various industrial facilities has affected the features of a significant part of downtown area, resulting in areas having buildings with a wide range of height and the foothills. To compute a velocity pressure exposure coefficient, namely the design wind speed factor, this study defines ground surface roughness by utilizing concentration analysis for the height of each building. After obtaining spatial data by extracting a building layer from digital maps, the study area was partitioned for the concentration analysis and to allow investigation of the frequency distribution of building heights. Concentration analysis by building height was determined with the Variation-to-Means Ratio (VMR) and Poisson distribution analysis using a buildings distribution chart, with statistical significance determined using Chi-square verification. Applying geographic information systems (GIS) with the architectural information made it possible to estimate a velocity pressure exposure coefficient factor more quantitatively and objectively, by including geographic features, as compared to current methods. Thus, this method is expected to eliminate inaccuracies that arise when building designers calculate the velocity pressure exposure coefficient in subjective way, and to help increase the wind resistance of buildings in a more logical and cost-effective way.

Blood Flow Measurement with Phase Contrast MRI According to Flip Angle in the Ascending Aorta (위상대조도 MRI에서 숙임각에 따른 상행대동맥의 혈류 측정)

  • Kim, Moon Sun;Kweon, Dae Cheol
    • Journal of the Korean Magnetics Society
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    • v.26 no.4
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    • pp.142-148
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    • 2016
  • To evaluate the effect of flip angle on flow rate measurements obtained with phase contrast MRI according to the flip angle degree in ascending aorta and velocity encoding (VENC) was (150 m/s). 1.5T MRI in patients 17 (female: 8, male: 9, mean age $57.9{\pm}15.4$) as a target by applying a non-breath holding techniques to flip angle VENC (150 cm/s) in each of the ascending aorta was measured by changing $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$. Blood was obtained a peak velocity, average velocity, net forward volume, net forward volume/body surface area. Ascending aorta from average velocity (AV) measured the average value of the flip angle $20^{\circ}$ (9.87 cm/s), $30^{\circ}$ (9.6 cm/s) and $40^{\circ}$ (10.05 cm/s). Blood flow VENC in was blood flow change in flip angle change was high most blood flow measurement when the flip angle $30^{\circ}$ in VENC, crouching each blood flow is also proportional to the increases in the $20^{\circ}$ to $40^{\circ}$ and was increased, the deviation of the peak velocity and the average velocity is the smallest deviation from the flip angle $30^{\circ}$. Flip angle $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$ in peak velocity, average velocity, net forward volume, net forward volume/body surface area was no statistically significant difference (p > .05). Blood flow velocity and blood flow is measured by applying to adjust the flip angle accurately calculate the blood flow is important information for diagnosis and treatment of cardiovascular diseases, and can help in the examination on the blood flow measurement.

Development of a High Resolution Cinematic Particle Image Velocimetry and Its Application to measurement of Unsteady Complex Turbulent Flows (고분해능 Cinematic PIV 시스템의 개발과 비정상 복잡 난류유동측정에의 응용)

  • Kim, Kyung-Chun;Park, Kyung-Hyun
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.536-541
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    • 2001
  • A high resolution digital cinematic Particle Image Velocimetry(PIV) has been developed. The system consists of a high speed CCD camera, a continuous Ar-ion laser and a computer with camera controller. To improve the spatial resolution, we adopt a Recursive Technique for velocity interrogation. At first, we obtain a velocity vector for a larger interrogation window size based on the conventional two-frame cross-correlation PIV analysis using the FFT algorithm. Based on the knowing velocity information, more spatially resolved velocity vectors are obtained in the next iteration step with smaller interrogation windows. The correct velocity vector at the first step is found to be critical, so we apply a Multiple Correlation Validation(MCV) technique in order to decrease the spurious vectors. The MCV technique turns out to improve SNR(Signal to Noise Ratio) of the correlation table. The developed cinematic PIV method has been applied to the measurement of the unsteady flow characteristics of a Rushton turbine mixer. A total of 3,245 instantaneous velocity vectors were successfully obtained with 4 ms time resolution. The acquired spatial resolution corresponds the performance of the conventional high resolution digital PIV system using a $1K{\times}1K$ CCD camera.

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Statistical Blade Angular Velocity Information-based Wind Turbine Fault Diagnosis Monitoring System (블레이드 각속도 통계 정보 기반 풍력 발전기 고장 진단 모니터링 시스템)

  • Kim, Byoungjin;Kang, Suk-Ju;Park, Joon-Young
    • KEPCO Journal on Electric Power and Energy
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    • v.2 no.4
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    • pp.619-625
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    • 2016
  • In this paper, we propose a new fault diagnosis monitoring system using gyro sensor-based angular velocity calculation for blades of the wind turbine system. First, the proposed system generates the angular velocity dataset for the rotation speed of the normal blade. Using the dataset, we estimate and evaluate the state of blades for the wind turbine by comparing the current state with the pre-calculated normal state. In the experimental results, the angular velocity of the normal state was higher than $360^{\circ}/s$ while that of the damaged blades was lower than $360^{\circ}/s$ and the standard deviation of the angular velocity was significantly increased.