• Title/Summary/Keyword: averaged method

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Research on Frequency Average Analysis of vibrational Power Flow Analysis (진동파워흐름해석의 주파수 평균해석에 대한 연구)

  • Lee, Jea-Min;Hong, Suk-Yoon;Park, Young-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.971-977
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    • 2005
  • Power Flow Analysis (PFA) is developed for the effective predictions of frequency-averaged vibrational response in medium-to-high frequency ranges. In PFA, the power coefficients of semi-infinite structure and for-field energy density are used to predict the vibrational responses of structures. Generally, at high frequencies, PFA can predict narrow-band frequency-averaged vibrational responses of built-up structures. However, in low- to medium frequency ranges, the dynamic responses obtained by PFA represent broad-band frequency-averaged vibrational energy densities. For the prediction of vibrational response variance in Power Flow Finite Element Method (PFFEM), the variances of input power and joint element matrix describing structural coupling relationship are derived. Finally, for the validity of developed formulation, numerical examples for two co-planer plates are performed and the vibrational response variance of the structure are compared with the results of classical and PFFEM solutions.

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Research on moving averaged ERD of EEG by the movement of body limbs (동작에 의한 뇌파의 이동평균성 ERD(Event Related Desynchronization)에 관한 연구)

  • 황민철;최철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.1252-1254
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    • 2004
  • BMI(brain machine interface) has been recently applied to give a disabled person mobility. This study is to determine the effective EEG parameters for predicting the movement moment of body limbs thought analysis of moving averaged ERD. The results showed that the proposed method for classifying EEG for predicting the movement seemed to be better than the classical method of determining ERD.

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Disk-averaged Spectra Simulation of Earth-like Exoplanets with Ray-tracing Method

  • Ryu, Dong-Ok;Kim, Sug-Whan
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.1
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    • pp.76.2-76.2
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    • 2012
  • The understanding spectral characterization of possible earth-like extra solar planets has generated wide interested in astronomy and space science. The technical central issue in observation of exoplanet is deconvolution of the temporally and disk-averaged spectra of the exoplanets. The earth model based on atmospheric radiative transfer method has been studied in recent years for solutions of characterization of earthlike exoplanet. In this study, we report on the current progress of the new method of 3D earth model as a habitable exoplanet. The computational model has 3 components 1) the sun model, 2) an integrated earth BRDF (Bi-directional Reflectance Distribution Function) model (Atmosphere, Land and Ocean) and 3) instrument model combined in ray tracing computation. The ray characteristics such as radiative power and direction are altered as they experience reflection, refraction, transmission, absorption and scattering from encountering with each all of optical surfaces. The Land BRDF characteristics are defined by the semi-empirical "parametric-kernel-method" from POLDER missions from CNES. The ocean BRDF is defined for sea-ice cap structure and for the sea water optical model, considering sun-glint scattering. The input cloud-free atmosphere model consists of 1 layers with vertical profiles of absorption and aerosol scattering combined Rayleigh scattering and its input characteristics using the NEWS product in NASA data and spectral SMARTS from NREL and 6SV from Vermote E. The trial simulation runs result in phase dependent disk-averaged spectra and light-curves of a virtual exoplanet using 3D earth model.

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Analysis of Shallow-Water Equations with HLLC Approximate Riemann Solver (HLLC Approximate Riemann Solver를 이용한 천수방정식 해석)

  • Kim, Dae-Hong;Cho, Yong-Sik
    • Journal of Korea Water Resources Association
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    • v.37 no.10
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    • pp.845-855
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    • 2004
  • The propagation and associated run-up process of nearshore tsunamis in the vicinity of shorelines have been analyzed by using a two-dimensional numerical model. The governing equations of the model are the nonlinear shallow-water equations. They are discretized explicitly by using a finite volume method and the numerical fluxes are reconstructed with a HLLC approximate Riemann solver and weighted averaged flux method. The model is applied to two problems; The first problem deals with water surface oscillations, while the second one simulates the propagation and subsequent run-up process of nearshore tsunamis. Predicted results have been compared to available analytical solutions and laboratory measurements. A very good agreement has been observed.

Velocity and Discharge Measurement using ADCP (ADCP를 이용한 유속과 유량 측정)

  • Lee, Chan-Joo;Kim, Won;Kim, Chi-Young;Kim, Dong-Gu
    • Journal of Korea Water Resources Association
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    • v.38 no.10 s.159
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    • pp.811-824
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    • 2005
  • The ADCP is an instrument based on Doppler effect, which measures discharge of a river in a short time while crossing it. In this study we aim to make a comparison of the discharge results from a moving-vessel ADCP with those measured by velocity-area method at the same cross-section, and to investigate the characteristics of velocity and discharge data using ADCP. Bathymetry measured by ADCP almost coincides with that by direct depth measurements. Because velocity data from ADCP are essentially instantaneous, individual velocity profiles obtained by ADCP are rather different from time-averaged velocity profiles. But spatially averaged velocity profiles of the individual ADCP data near the comparable verticals have similar vertical velocity pattern with the time-averaged ones. The average velocity profile from repeatedly crossed data is also similar with the time-averaged one. In case of the velocity distribution, individual and spatially averaged data for the sub-width of mid-section method Have good agreement with those by velocity-area method. Discharge data determined by averaging several ADCP measurement transects have $0.1\%{\~}9.3\%$ of difference with those from velocity-area method, and as the number of measurement increases, the relative difference to the velocity-area method decreases.

A Study on the long-term Hemodialysis patient중s hypotension and preventation from Blood loss in coil during the Hemodialysis (장기혈액투석환자의 투석중 혈압하강과 Coil내 혈액손실 방지를 위한 기초조사)

  • 박순옥
    • Journal of Korean Academy of Nursing
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    • v.11 no.2
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    • pp.83-104
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    • 1981
  • Hemodialysis is essential treatment for the chronic renal failure patient's long-term cure and for the patient management before and after kidney transplantation. It sustains the endstage renal failure patient's life which didn't get well despite strict regimen and furthermore it becomes an essential treatment to maintain civil life. Bursing implementation in hemodialysis may affect the significant effect on patient's life. The purpose of this study was to obtain the basic data to solve the hypotension problem encountable to patient and the blood loss problem affecting hemodialysis patient'a anemic states by incomplete rinsing of blood in coil through all process of hemodialysis. The subjects for this study were 44 patients treated hemodialysis 691 times in the hemodialysis unit, The .data was collected at Gang Nam 51. Mary's Hospital from January 1, 1981 to April 30, 1981 by using the direct observation method and the clinical laboratory test for laboratory data and body weight and was analysed by the use of analysis of Chi-square, t-test and anlysis of varience. The results obtained an follows; A. On clinical laboratory data and other data by dialysis Procedure. The average initial body weight was 2.37 ± 0.97kg, and average body weight after every dialysis was 2.33 ± 0.9kg. The subject's average hemoglobin was 7.05±1.93gm/dl and average hematocrit was 20.84± 3.82%. Average initial blood pressure was 174.03±23,75mmHg and after dialysis was 158.45±25.08mmHg. The subject's average blood ion due to blood sample for laboratory data was 32.78±13.49cc/ month. The subject's average blood replacement for blood complementation was 1.31 ±0.88 pint/ month for every patient. B. On the hypotensive state and the coping approaches occurrence rate of hypotension was 28.08%. It was 194 cases among 691 times. 1. In degrees of initial blood pressure, the most 36.6% was in the group of 150-179mmHg, and in degrees of hypotension during dialysis, the most 28.9% in the group of 40-50mmHg, especially if the initial blood pressure was under 180mmHg, 59.8% clinical symptoms appeared in the group of“above 20mmHg of hypotension”. If initial blood pressure was above 180mmHg, 34.2% of clinical symptoms were appeared in the group of“above 40mmHg of hypotension”. These tendencies showed the higher initial blood pressure and the stronger degree of hypotension, these results showed statistically singificant differences. (P=0.0000) 2. Of the occuring times of hypotension,“after 3 hrs”were 29.4%, the longer the dialyzing procedure, the stronger degree of hypotension ann these showed statistically significant differences. (P=0.0142). 3. Of the dispersion of symptoms observed, sweat and flush were 43.3%, and Yawning, and dizziness 37.6%. These were the important symptoms implying hypotension during hemodialysis accordingly. Strages of procedures in coping with hypotension were as follows ; 45.9% were recovered by reducing the blood flow rate from 200cc/min to 1 00cc/min, and by reducing venous pressure to 0-30mmHg. 33.51% were recovered by controling (adjusting) blood flow rate and by infusion of 300cc of 0,9% Normal saline. 4.1% were recovered by infusion of over 300cc of 0.9% normal saline. 3.6% by substituting Nor-epinephiine, 5.7% by substituting blood transfusion, and 7,2% by substituting Albumin were recovered. And the stronger the degree of symptoms observed in hypotention, the more the treatments required for recovery and these showed statistically significant differences (P=0.0000). C. On the effects of the changes of blood pressure and osmolality by albumin and hemofiltration. 1. Changes of blood pressure in the group which didn't required treatment in hypotension and the group required treatment, were averaged 21.5mmHg and 44.82mmHg. So the difference in the latter was bigger than the former and these showed statistically significant difference (P=0.002). On the changes of osmolality, average mean were 12.65mOsm, and 17.57mOsm. So the difference was bigger in the latter than in the former but these not showed statistically significance (P=0.323). 2. Changes of blood pressure in the group infused albumin and in the group didn't required treatment in hypotension, were averaged 30mmHg and 21.5mmHg. So there was no significant differences and it showed no statistical significance (P=0.503). Changes of osmolality were averaged 5.63mOsm and 12.65mOsm. So the difference was smaller in the former but these was no stitistical significance (P=0.287). Changes of blood pressure in the group infused Albumin and in the group required treatment in hypotension were averaged 30mmHg and 44.82mmHg. So the difference was smaller in the former but there is no significant difference (P=0.061). Changes of osmolality were averaged 8.63mOsm, and 17.59mOsm. So the difference were smaller in the former but these not showed statistically significance (P=0.093). 3. Changes of blood pressure in the group iutplemented hemofiltration and in the Uoup didn't required treatment in hypotension were averaged 22mmHg and 21.5mmHg. So there was no significant differences and also these showed no statistical significance (P=0.320). Changes of osmolality were averaged 0.4mOsm and 12.65mOsm. So the difference was smaller in the former but these not showed statistical significance(P=0.199). Changes of blood pressure in the group implemented hemofiltration and in the group required treatment in hypotension were averaged 22mmHg and 44.82mmHg. So the difference was smatter in the former and these showed statistically significant differences (P=0.035). Changes of osmolality were averaged 0.4mOsm and 17.59mOsm. So the difference was smaller in the former but these not showed statistical significance (P=0.086). D. On the changes of body weight, and blood pressure, between the group of hemofiltration and hemodialysis. 1, Changes of body weight in the group implemented hemofiltration and hemodialysis were averaged 3.340 and 3.320. So there was no significant differences and these showed no statistically significant difference, (P=0.185) but standard deviation of body weight averaged in comparison with standard difference of body weight was statistically significant difference (P=0.0000). Change of blood Pressure in the group implemented hemofiltration and hemodialysis were averaged 17.81mmHg and 19.47mmHg. So there was no significant differences and these showed no statistically significant difference (P=0.119), But in comparison with standard deviation about difference of blood pressure was statistically significant difference. (P=0.0000). E. On the blood infusion method in coil after hemodialysis and residual blood losing method in coil. 1, On comparing and analysing Hct of residual blood in coil by factors influencing blood infusion method. Infusion method of saline 200cc reduced residual blood in coil after the quantitative comparison of Saline Occ, 50cc, 100cc, 200cc and the differences showed statistical significance (p < 0.001). Shaking Coil method reduced residual blood in Coil in comparison of Shaking Coil method and Non-Shaking Coil method this showed statistically significant difference (P < 0.05). Adjusting pressure in Coil at OmmHg method reduced residual blood in Coil in comparison of adjusting pressure in Coil at OmmHg and 200mmHg, and this showed statistically significant difference (P < 0.001). 2. Comparing blood infusion method divided into 10 methods in Coil with every factor respectively, there was seldom difference in group of choosing Saline 100cc infusion between Coil at OmmHg. The measured quantity of blood loss was averaged 13.49cc. Shaking Coil method in case of choosing saline 50cc infusion while adjusting pressure in coil at OmmHg was the most effective to reduce residual blood. The measured quantity of blood loss was averaged 15.18cc.

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A Study on the Method of the Analysis of the Base Gummel Number of the BJT for Integrated Circuits (직접회로용 BJT의 베이스 Gummel Number 해석 방법에 관한 연구)

  • 이은구;김철성
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.2
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    • pp.74-79
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    • 2003
  • The method of the analysis of the base Gummel number of the BJT(Bipolar Junction Transistor) for integrated circuits based upon the semiconductor physics is proposed and the method of calculating the doping profile of the base region using process conditions is presented. The transistor saturation current obtained from the proposed method of NPN BJT using 20V and 30V process shows an averaged relative error of 6.7% compared with the measured data and the transistor saturation current of PNP BJT shows an averaged relative error of 9.2% compared with the measured data

A Study on Performance Analysis of High Resolution DOA Method based on MUSIC (MUSIC을 근간으로 하는 고해상도 DOA 방법의 성능분석에 관한 연구)

  • 이일근;최인경;김영집;강철신
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.2
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    • pp.345-353
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    • 1994
  • This paper proposes a high resolution direction finding method, which is so called the 'averaged MUSIC'. This method uses a new sample array covariance matrix that consists of diagonal components obtained by taking averages of the diagonal component values of the sample covariance matrix for the MUSIC. This paper also shows that the proposed method performs higher resolced direction-of-arrival estimation than the MUSIC in such cases as low signal-to-noise ratio, closed signal sources, and limited number of sensors, based on the statistical analysis.

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Three-Dimensional Flow Analysis and Improvement of Slip Factor Model for Forward-Curved Blades Centrifugal Fan

  • Guo, En-Min;Kim, Kwang-Yong
    • Journal of Mechanical Science and Technology
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    • v.18 no.2
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    • pp.302-312
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    • 2004
  • This work developed improved slip factor model and correction method to predict flow through impeller in forward-curved centrifugal fan. Both steady and unsteady three-dimensional CFD analyses were performed to validate the slip factor model and the correction method. The results show that the improved slip factor model presented in this paper could provide more accurate predictions for forward-curved centrifugal impeller than the other slip factor models since the present model takes into account the effect of blade curvature. The correction method is provided to predict mass-averaged absolute circumferential velocity at the exit of impeller by taking account of blockage effects induced by the large-scale backflow near the front plate and flow separation within blade passage. The comparison with CFD results also shows that the improved slip factor model coupled with the present correction method provides accurate predictions for mass-averaged absolute circumferential velocity at the exit of impeller near and above the flow rate of peak total pressure coefficient.

A numerical study on ship-ship interaction in shallow and restricted waterway

  • Lee, Sungwook
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.5
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    • pp.920-938
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    • 2015
  • In the present study, a numerical prediction method on the hydrodynamic interaction force and moment between two ships in shallow and restricted waterway is presented. Especially, the present study proposes a methodology to overcome the limitation of the two dimensional perturbation method which is related to the moored-passing ship interaction. The validation study was performed and compared with the experiment, firstly. Afterward, in order to propose a methodology in terms with the moored-passing ship interaction, further studies were performed for the moored-passing ship case with a Reynolds Averaged Navier-Stokes (RANS) calculation which is using OpenFOAM with Arbitrary Coupled Mesh Interface (ACMI) technique and compared with the experiment result. Finally, the present study proposes a guide to apply the two dimensional perturbation method to the moored-passing ship interaction. In addition, it presents a possibility that the RANS calculation with ACMI can applied to the ship-ship interaction without using a overset moving grid technique.