• 대한기계학회논문집B
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• 제27권1호
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• pp.1-8
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• 2003

The heat transfer and flow measurements on a cylindrical pedestal mounted on a flat surface with a turbulent impinging jet were made. The experiments were made for the jet Reynolds number of Re = 23,000, the dimensionless nozzle-to-surface distance of L/d = 2~10, the dimensionless pedestal height of H/D = 0~1.5. Measurements of the surface temperature and the Nusselt number distributions on the plate surface were made using liquid crystal and shroud-transient technique. Flow measurements involve smoke flow visualization and the wall pressure coefficient. The results show that the wall pressure coefficient sharply decreases along the upper surface of the pedestal. However, the pressure increases when the fluid escapes from the pedestal and then collides on the plate surface. The secondary maxima in the Nusselt numbers occur in the region of 1.0 $\leq$ r/d $\leq$ 1.9. Their values for the case of H/D = 0.5 are maximum 80% higher than those for other cases. The formation of the secondary maxima may be attributed to the reattachment of flow on the plate surface which was separated at the edge of the pedestal.

• 설비공학논문집
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• 제7권1호
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• pp.112-119
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• 1995

Measurements of the local heat transfer coeffcients on a spherically concave surface with a round impinging jet are presented. The liquid crystal transient method was used for these measurements. This method, which is a variation on the transient method, suddenly exposes a preheated wall to an impinging jet while video recording the response of liquid crystals for the measurement of the surface temperature. The Reynolds numbers used were 1,000, 23,000 and 50,000 and the nozzle-to-jet distance was L/d=2, 4, 6, 8, 10. Presented results are compared to previous measurements for flat plate. In the experiment, the local heat transfer Nusselt numbers on a concave surface are higher than those on a flat plate. Maximum Nusselt number at all region occured at L/d=6 and second maximum in the Nusselt number occured at R/d=2 for both Re=50,000 and Re=23,000 in case of L/d=2 and for only Re=50,000 in case of L/d=4. All other cases exhibit monotonically decreasing value of the Nusselt number along the curved surface.

• Journal of Acupuncture Research
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• 제19권6호
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• pp.12-23
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• 2002

Objective : Assuming That the Characteristic of Meridian System Has been Similar to This of Electric Potentials in Human Body And that Measurements of Electric Potential at Well(井穴) and Sea(合穴) Points in Branches of the Twelve Meridians(WSBTM) Will Be Representative of Measurements of the Twelve Meridians, to Measure the Electric Potentials of 21 Patients with Shoulder Lesions, And Aching of Shoulder and Arm(肩臂痛)(ASA), to Be Differences in Electric Potentials of Patients Between Before And After Acupuncture Treatment, And Then to Find out the Characteristic of Meridian System in Patients with Shoulder Lesions. Methods : Electric Potentials of Well And Sea Points in the Meridians in Twenty one Patients with ASA Diagnosed by Both x-ray And Self View on Pain at Shoulder And Arm were Repeatedly Measured by Physiograph(PowerLab) at Before And after Acupuncture Treatment, Respectively. Measurements of Those Electrical Potentials Were Analyzed by Factor Analysis. Results : The Electric Potentials of WSBTM At the Left Side Before Acupuncture Treatment Were Divided Into Five Factors, But Those After Acupuncture Treatment Were Done Into Four Factors. On The Other Hand Those At the Right Side Before Acupuncture Treatment Were Divided Into Four Factors, The Number of Factors After Acupuncture Treatment Was Five. Conclusions : In Conclusions, The Number of Factors Before Acupuncture Treatment Are Different from Those After Acupuncture Treatment. In the Results The Effect of Acupuncture Treatment May be Reflected in Measurements of Electric Potential at WSBTM.

• Journal of Biosystems Engineering
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• 제40권2호
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• pp.115-123
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• 2015

Purpose: A sampling scheme may significantly affect the accuracy of a sensor. This study was conducted to investigate the effects of sampling point locations on optical reflectance measurements of Chinese cabbage and kale plant leaves. Methods: Variability and similarity of multiple measurements for different parts of the leaves were compared. Results: The results indicate that the variability between the average and individual reflectance spectra was smaller for the blade part than for the vein part. Furthermore, the reflectance for the blade part over the upper leaf area was greater and more stable than those for the other parts for both the cabbage and kale leaf samples. Conclusions: The results provide guidelines for optical reflectance measurements of Chinese cabbage and kale plants. The effects of the number of sampling points, the number of leaves, and the relationships between optical reflectance and leaf components remain to be investigated in the future.

• 음성과학
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• 제15권3호
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• pp.39-51
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• 2008

Formant measurements are one of the most important factors to objectively test cross-linguistic differences among vowels produced by speakers of any given languages. However, many speech analysis softwares present erroneous estimates and some researchers use them without any verification procedures. The purposes of this paper are to examine formant measurements of complex waves which were synthesized from the average formant values of five Korean vowels using three default methods in Praat and to verify the measured values of the five vowels produced by 20 students using one of the methods. Variances along the time axis are discussed after determining absolute difference sum from the 1/3 vowel duration point. Results show that there were smaller measurement errors by the burg method. Also, greater errors were observed in the sl or lpc methods mostly caused by the inappropriate formant settings. Formant measurement deviations were greater in those vowels produced by the female students than those of the male students, which were mostly attributed to the settings for the vowels /o, u/. Formant settings can best be corrected by changing the number of formants to the number of visible dark bands on the spectrogram. Those results suggest that researchers should check the validity of the estimates from the speech analysis software. Further studies are recommended on the perception test of the original sound with the synthesized sound by the estimated formant values.

• Wind and Structures
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• 제7권5호
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• pp.305-316
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• 2004

In this study, a wind tunnel, that has been developed for experiments of wind turbine rotor blades, has been considered. The deviations of the measurements have been examined after this wind tunnel had been introduced and the measurements on it had been explained. Two different wind turbine rotor blades miniatures have been used for getting better results from the experiments. The accuracy of measurements have been experimented three times repetitively and examined statistically. As a result, wind speed values which this type of wind tunnel and wind turbine rotors need for starting, wind speed in the tunnel, temperature and moisture values, the number of rotor's revolution, and the voltage that is produced in 102 ${\Omega}$ resistance and current values have been determined to be fixed by measurements used. This type of wind tunnel and wind turbine rotor' performance difference and the difference of revolution figures have been determined to be fixed by measurements used.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권2호
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• pp.45-53
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• 2013

Many cases of strategically designed groundwater remediation have lack of information of hydraulic conductivity or permeability, which can render remediation methods inefficient. Many studies have been carried out to minimize this shortcoming by determining detailed hydraulic information either through direct or indirect measurements. One popular method for hydraulic characterization is the pilot point method (PPM), where the hydraulic property is estimated at a small number of strategically selected points using secondary measurements such as hydraulic head or tracer concentration. This paper adopted a D-optimality based pilot point method (DBM) developed previously for hydraulic head measurements and extended it to include both hydraulic head and tracer measurements. Based on different combinations of trials, our analysis showed that DBM performs well when hydraulic head is used for pilot point selection and both hydraulic head and tracer measurements are used for determining the conductivity values.

• International Journal of Control, Automation, and Systems
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• 제5권4호
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• pp.388-396
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• 2007

This paper describes a multipath estimation method for Global Positioning System (GPS) dual frequency carrier phase measurements. Multipath is a major error source in high precision GPS applications, i.e., carrier phase measurements for precise positioning and attitude determinations. In order to estimate and remove multipath at carrier phase measurements, an array GPS antenna system has been used. The known geometry between the antennas is used to estimate multipath parameters. Dual frequency carrier phase measurements increase the redundancy of measurements, so it can reduce the number of antennas. The unscented Kalman filter (UKF) is recently applied to many areas to overcome some of the limitations of the extended Kalman filter (EKF) such as weakness to severe nonlinearity. This paper uses the UKF for estimating multipath parameters. A series of simulations were performed with GPS antenna arrays located on a straight line with one reflector. The geometry information of the antenna array reduces the number of estimated multipath parameters from four to three. Both the EKF and the UKF are used as estimation algorithms and the results of the EKF and the UKF are compared. When the initial parameters are far from true parameters, the UKF shows better performance than the EKF.

• Journal of Advanced Marine Engineering and Technology
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• 제15권5호
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• pp.23-29
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• 1991

Uncertainty is studied in the measurements of average packing density, thickness of packed spheres and transmittance in the experiments to study the effect of the bed height and the existence of the bed side walls on the transmittance of radiative energy through packed spheres. The packing density of the bed is obtained by counting the number of the spheres packed in three pipes with different heights. The bed height of the packed spheres is estimated from the number of spheres contained in the bed by using the relation between the bed height and the sphere number. The transmittance is obtained by dividing the intensity of the transmitted laser beam by the incoming-beam intensity. From the analysis, the uncertainity in the measurements of transmittance is shown to be less than 10.2%(95% coverage).

• International Journal of Fluid Machinery and Systems
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• 제8권2호
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• pp.63-72
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• 2015

Water hammer phenomena are important issues for the design and the operation of hydro power plants. Especially, if several reversible pump-turbines are coupled hydraulically there may be strong unit interactions. The precise prediction of all relevant transients is challenging. Regarding a recent pump-storage project, dynamic measurements motivate an improved turbine modeling approach making use of a Thoma number dependency. The proposed method is validated for several transient scenarios and turns out to improve correlation between measurement and simulation results significantly. Starting from simple scenarios, this allows better prediction of more complex transients. By applying a fully automated simulation procedure broad operating ranges of the highly nonlinear system can be covered providing a consistent insight into the plant dynamics. This finally allows the optimization of the closing strategy and hence the overall power plant performance.