• International Journal of Internet, Broadcasting and Communication
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• 제12권3호
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• pp.1-8
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• 2020

This paper studied a method of estimating target information using a radar in wireless communication. Position information on the target can be estimated angle, distance and velocity. The velocity information can be estimated since the Doppler frequency is changed in the moving target. The signal incident on the receiving array antenna is multiplied by the delay time and the reference signal to represent the output signal. This output signal is estimated by applying FFT (Fast Fourier Transform) after calculating signal correlation through correlation integrator. Since the output signal must be calculated within the correlator, it should be processed with the Dwell time. The correlation signal of the correlation integrator outside this Dwell time is indicated by the velocity measurement error. The FFT is applied to the signal that has passed through the correlated integrator in order to estimate the distance of the signal. The Doppler resolution must be improved because the FFT estimates target information using the Doppler information. The Doppler resolution decreases with increasing the integration time. The velocity information estimation should have no spread of the velocity. As a result of the simulation, there was no spread of the target velocity in this study.

• 대한물리의학회지
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• 제4권3호
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• pp.157-164
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• 2009

Purpose：The purpose of this study was to investigate the effects of angular velocity on muscle strength of biceps brachii. Methods：Subjects was classified into two groups, which were $60^{\circ}/sec$ angular velocity group(n=15) and $240^{\circ}/sec$ angular velocity group(n=15). Each group was applied to perform the isokinetic exercises on flexion muscle group for each 10 times in 3 set(3 days per a week for 2 weeks). Muscle strength was measured using peak torque of biceps brachii. Results：The results were as follows: The peak torque was significantly increased after $60^{\circ}/sec$ angular velocity isokinetic exercise application(p<.05), however, it was not significantly after $240^{\circ}/sec$ angular velocity isokinetic exercise application(p>.05). Conclusions：This study showed that $60^{\circ}/sec$ angular velocity isokinetic exercise application were effective treatment strategy on increase of muscle strength. Therefore, it could be considered as a treatment method in the athlete and patients with musculoskeletal disease.

• 한국유체기계학회 논문집
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• 제5권4호
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• pp.54-60
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• 2002

Experimental study was conducted to obtain the air velocity profiles in turbulent pipe flow. The acrylic smooth pipe (${\phi}=80mm$) was used for the test section of the flow loop. It was known that the velocity profiles of turbulent flow were different with Reynolds numbers and the viscous sublayer was usually quite thin. The following conclusions were drawn from the experimental investigations. Maximum velocity of the pipe center and flow-rate are useful for the duct design on the spot. The velocity profiles of high Reynolds number was flatter than those of low Reynolds number. It was known that the exponent, n, for power-law velocity profiles was $6{\sim}9$ depending on Reynolds number ranging from $10^4$ to $10^5$ in the turbulent flow, However, in this experiment study, it was $9{\sim}14$ depending on Reynolds number ranging from 17,000 to 123,727 in the turbulent flow, and $1.7{\sim}3.5$ depending on Reynolds number ranging from 2,442 to 4,564 in the transition region.

• 대한기계학회논문집B
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• 제31권7호
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• pp.644-652
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• 2007

In this paper, a technique of simultaneously measuring the velocity and the temperature in micro-scale flow is proposed. This method uses particle tracking velocimetry (PTV) for measuring the velocity and laser induced fluorescence (LIE) for measuring the temperature. To measure the accurate velocity and temperature, images for PTV and for LIE are separated by using two light sources and a shutter which is synchronized with a camera. By using only one camera, measurement system can be simplified and the error from complicate optical system can be minimized. Error analyses regarding the concentrations of fluorescent dye and particle and the light source fluctuation are also conducted. It is found that the error of the temperature and the velocity highly depends on the concentration of fluorescent particles which are used for PTV. This technique is applied to the simultaneous measurement of the velocity and the temperature in the electrokinetic flow. It is found that the velocity and temperature vary with the electric field strength and the concentration of electrolyte.

• 오토저널
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• 제4권3호
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• pp.56-68
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• 1982

This paper presents analytic solutions of defection and their resonance diagrams for a uniform beam of infinite length subjected to an constant axial force and moving transverse load simultaneously. Steady solutions are obtained by a time-independent coordinate moving with the load. The supporting foundation includes damping effects. The influences of the axial force, the damping coefficient and the load velocity on the beam response are studied. The limiting cases of no damping and critical damping are also investigate. The profiles of the deflection of the beam are shown graphically for several values of the load speed, the axial force and damping parameters. Form the results, following conclusions have been reached. 1. The critical velocity .THETA.cr decreases as the axial compressive force increases, but increases as the axial tensile force increase. 2. At the critical velocity .THETA.cr the deflection have a tendency to decrease as the axial tensile force increases and to increase gradually as the axial compressive force increases. 3. In case if relatively small dampings, the deflection increases suddenly as the velocity of the moving load approaches the critical velocity, and it reachs its maximum at the critical velocity, and it decreases and become greatly affected by the axial force as the velocity increases further. 4. in case of relatively large dampings, as the velocity increases the deflection decreases gradually and it is affected little by the axial load.

• 한국정밀공학회지
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• 제31권8호
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• pp.705-713
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• 2014

In this paper, we propose a novel velocity ripple controller using phase compensation feedforward control. Velocity ripples result in many kinds of performance degradations in manufacturing machines, especially such as ultra-precision roll lathes. The generation of velocity ripple in constant velocity control comes from various causes, such as electrical torque ripples, mechanical worn out, inconsistent mass center, etc. Conventional researches about ripple is mainly for reducing torque ripple in actuator level, which is only one of reasons for velocity ripples, so in this study, we focus on eliminating velocity ripples in upper level controller using phase compensation feedforward controller. The proposed algorithm is composed of several modules, such as ripple extractor, phase adjuster and phase follower etc. The suggested algorithm can be easily extended, and it shows a superior performance in the experiments of ultra-precision roll lathes.

• 환경위생공학
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• 제10권3호
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• pp.1.1-15
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• 1995

This study was performed to estimate the characteristics of the organic wastewater treatment and bed porosity with the circulation velocity in the anaerobic fluidized bed biofilm reactor. The results were as follows; 1. With Increasing circulation velocity the fluidized bed expanded smooth and with increasing initial particle volume the fluidized bed was increased. 2. With increasing circulation velocity the gasproduction was increased, but at 1.Scnt/sec of circulation velocity AFBBR showed the highest value of methane production rate per removed COD. Therefore, for the purpose of economical operation in AFBBR, 1.5cm/sec of circulation velocity was optimum 3. The microorganisms were colonized in the crevice of the media. 4. On fluidization, COD, VA,55 profiles with the reactor height were not showed. In conclusion, AFBBR suit the organic wastewater treatment's purpose, and at 1.5cm/sec of circulation velocity the system is economical in an energy Point of view.

• 한국운동역학회지
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• 제13권3호
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• pp.27-46
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• 2003

The purposes of this study were to determine the functions of actions of the limbs during each of the three support phases of the triple jump and their relationships with the performance of the triple jump. Four elite male triple jumpers were participated as subjects. The statistical analyses used were the Pearson product moment correlation coefficient for establishing relationships and simple regression analyses to determine and compare the relationships between the change of the horizontal velocity and the change of the vertical velocity during different support phases. A level of significance at p<.05 was set. The actions of the arms were responsible for about 25%, 25%, and 30% of the decrease in the horizontal velocity of the whole body center of gravity during the support phases of the hop, step, and jump, respectively. The change in the velocities of the whole body center of gravity due to the actions of the free limbs were significantly related with the whole body center of gravity during each support phase. The action of the support leg was associated with the decrease in the horizontal velocity and the increase in the vertical velocity of the whole body center of gravity during each support phase.

• 한국안전학회지
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• 제20권2호
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• pp.44-49
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• 2005

Real-scale experimental study was performed to characterize the surface flame propagating velocity along the OF cable in the underground utility fire. Temperatures of oil filled OF cable and dried OF cable with the diameter of 90mn were measured using thermocouple and data log system. The hexane and alkyl-benzene oil were used as a fire source using the ignition device. As a result while the surface flame propagating velocity of the three cables was $0.06\~0.09cm/s$, the surface flame propagating velocity of the one cable was $0.028\~0.032cm/s$. Therefore, it was found that the surface propagating flame velocity of the three OF cables is $2.1\~2.8times$ faster than that of one OF cable case. The results show that the surface propagating flame velocity became larger as increase of the number of cable, the volume of alkyl-benzene oil in the cable. The characteristics of surface propagating flame velocity in the OF cable can be helpful to fire suppression system in utility.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
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• pp.127-133
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• 2000

In the present study flow characteristics of turbulent pulsating flow in a square-sectional 180。 curved duct are investigated experimentally. in order to measure axial velocity and secondary flow distributions experimental studies for air flow are conducted in a square-sectional $180^{\circ}$ curved duct by using the LDV system with the data acquisition and the processing system of the Rotating Machinery Resolver (RMR) and the PHASE software. The experiment is conducted on seven sections form the inlet(${\phi}=180^{\circ}$) at $30^{\circ}$ intervals of the duct. The results obtained from the experimentation are summarized as follows : In the axial velocity distributions of turbulent pulsating flow when the ratio of velocity amplitude(A1) is less than one there is hardly any velocity change in the section except near the wall and any change in axial velocity distribution along the phase. The secondary flow of turbulent pulsating flow has a positive value at the vend angle of $150^{\circ}$ without regard to the ratio of velocity amplitude. The dimensionless value of secondary flow becomes gradually weak and approaches zero in the region of bend angle $180^{\circ}$ without regard to the ratio of velocity amplitude.