• Title/Summary/Keyword: mean and maximum velocity

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A Study on Maximum and Mean Velocity Relationships with Varied Channel Slopes and Sediment (유사가 있는 경우와 수로경사가 변화하는 경우의 최대유속과 평균유속과의 관계에 관한 연구)

  • Choo, Tai-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.1
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    • pp.154-159
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    • 2008
  • This study proposes how to decide mean velocity which is one of the very important and efficient discharge measurement in water resources area. In order to achieve this goal, Chiu's velocity distribution equation recently developed from the probability and entropy concepts is used to establish, analyze and compare a linkage between the mean velocity obtained from the Manning's equation which is well known in the world. Besides, it becomes clear that a channel cross section also has a propensity to establish and maintain an equilibrium state that can be measured and classified by a function of entropy M, ratio of mean and maximum velocities irrespective of including sediment or varied channel slope. Therefore, The linkage to be established in this study can be used to compute the cross sectional velocity distribution with the maximum velocity.

A STUDY ON THE MANDIBULAR MOVEMENTS OF TMD PATIENTS (두개하악장애 환자의 하악운동에 관한 연구)

  • Heo, Seong-Joo;Kim, Kwang-Nam;Chang, Ik-Tae
    • The Journal of Korean Academy of Prosthodontics
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    • v.32 no.1
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    • pp.103-119
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    • 1994
  • The purpose of this study was to evaluate the mandibular movements of TMD patients comparing to normal persons. Sirognathograph was used to measure five parameters of mandibular movements of twenty normal persons and eight TMD patients. Five parameters were (1) Maximum opening during maximum opening and closing, (2) Mean velocity during maximum opening and closing, (3) Maximum opening during unilateral chewing, (4) Mean velocity during unilateral chewing, (5) Consistency of mandibular movement during unilateral chewing. Based on above results, new Mandibular Movement Index(M.M.I.) was formulated and compared to Helkimo's Clinical Dysfunction Index by measuring two indices before treatment and 2 weeks, 4 weeks, 6 weeks, 8 weeks after treatment. The conclusions were as follows: 1, The amounts of maximum opening and mean velocity during maximum opening and closing of TMD patients were less than those of normal persons(p<0.01). 2. The amounts of maximum opening and mean velocity during unilateral chewing of TMD patients were less than those of normal persons(p<0.05) (P<0.01). 3. Although TMD patients showed limited mandibular movements during unilateral chewing, the consistency of mandibular movements was better than that of normal persons(p<0.05). 4. Both mandibular movement index and Helkimo's Clinical Dysfunction Index, were useful in diagnosing TMD patients.

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An Experimental Study on the Lift-off Characteristics of the Triple Flame with Concentration Gradient (농도구배가 삼지화염의 부상특성에 미치는 영향에 관한 실험적 연구)

  • Seo, Jeong-Il;Kim, Nam-Il;Oh, Kwang-Chul;Shin, Hyun-Dong
    • 한국연소학회:학술대회논문집
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    • 2004.06a
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    • pp.7-14
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    • 2004
  • The lift-off characteristics of the triple flame have been studied experimentally with various mean velocities and concentration gradients using a multi-slot burner, which can control the concentration gradient and the mean velocity independently, Lift-off height, axial maximum velocity, flame temperature, and some other characteristics were examined for methane and propane flame, It was found that minimum values of the lift-off heights exist at a certain concentration gradient for constant mean velocity, and this result implies that the propagation velocity has a maximum value at this condition, OH radical distribution was measured with LIF method and velocity variation along streamline was measured with PlV system. In addition maximum temperature along streamline was measured with CARS system. The intensity of the diffusion flame affects on the propagation velocity of triple flame in the region of very weak concentration gradient.

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A Study on Mandibular Opening and Closing Movements at Mandibular incisor region and Clinical Rest Position (하악 전치부의 개폐운동과 안정위에 관한 연구)

  • Ahn, Seung-Geun;Song, Kwang-Yeob;Park, Charn-Woon
    • The Journal of Korean Academy of Prosthodontics
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    • v.27 no.2
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    • pp.143-154
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    • 1989
  • The purpose of this study was to investigate the mandibular opening and closing movements at mandibular incisor region and clinical rest position in normal subject using the newly developed electric mandibular movement analyzing device, (M.K.G.-K6 diagnostic system, Myo-tronics Inc. Seattle, WA, U.S.A.) The 58 normal subjects, who were students of the College of Dentistry, Chonbuk National University, were selected according to sampling criteria. The obtained results were as follows: 1. There was no significant difference of distribution of opening and closing movement patterns at mandibular incisor region between male and female. There was significant difference between habitual and maximum movement patterns both in sagittal and frontal plane. 2. Although the percentage of distribution of crossover pattern was highest in all cases, but there were significant differences between patterns only at habitual opening and closing movement in sagittal plane. 3. The mean of maximum opening was $47.29{\pm}4.68mm$ in male and $42.15{\pm}4.95mm$ in female. Therefore the mean of maximum opening was larger in male than in female. 4. The mean of maximum laterotrusion in frontal trajectory was larger to the left than to the right. Also the proportion of left deviation at maximum opening position was larger than that of other cases. 5. The mean of maximum opening and closing velocity was higher in male than in female and the mean of closing velocity was higher than that of opening velocity. Also the amount of separation from the centric occlusion was higher in maximum closing velocity than in maximum opening velocity. 6. Clinical rest position was $1.70{\pm}0.99mm$ inferior, $0.74{\pm}0.57mm$ anterior, $0.99{\pm}0.51mm$ right from centric occlusion and the A/V ratio was 1:2.7.

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The Influences of Factors on Turbulence Intensity in Combustion Chamber (연소실내의 난류강도에 미치는 각종 인자의 영향)

  • 한성빈;이상준;이종태;이성열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.3
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    • pp.793-804
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    • 1994
  • Turbulence intensity caused by piston movement was almost as same tendency as the piston speed. The turbulence intensity was increased from 0.39m/s to 0.79m/s when mean piston speed increased from 2.33m/s to 4.67m/s. In this case the maximum turbulence intensity caused by piston speed was decreased about 82 percent near the top dead center at the end of compression stroke. The maximum turbulence intensity was created from 12m/s to 22m/s when inlet flow velocity was increased from 22m/s to 45m/s. Also turbulence intensity caused by inlet flow velocity was linearly increased from 0.97m/s at top dead center at the end of compression stroke. The ratio of turbulence intensity and mean inlet flow velocity was about 3 percent for inlet flow velocity.

Transport Velocity of Perilla Grain on Oscillating Sieve in Elliptical Motion

  • Pang, Yeoun Gyu;Kim, Sang Hun
    • Journal of Biosystems Engineering
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    • v.43 no.3
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    • pp.194-201
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    • 2018
  • Purpose: The objective of this study was to propose a formula for the theoretical grain mean transport velocities of an elliptically moving oscillator by modifying the grain mean transport velocity formula applied to linear motion and to compare the calculated values with the experimental values of grain mean transport velocity. Methods: The values of the throwing index ($K_v$) and the maximum horizontal velocities for various positions on the elliptical oscillator were obtained using kinematic analysis. To obtain the actual grain transport velocity, the mean transport velocities of perilla grains at six positions on the sieve surface were measured using a high-speed camera and compared with the theoretical values. The cam with an eccentric bearing on the oscillator was designed to be eccentric by 1.6 cm so that the lengths of the major axis of the elliptical motion were 3.2-3.6 cm. The material used in the experiments was perilla grain. Results: The experimental result was consistent with the theoretical value calculated using the proposed formula ($R^2$ is 0.80). It is considered that the angle difference between the maximum accelerations in the directions vertical and horizontal to the sieve has as much influence on the grain mean transport velocity as the value of Kv itself. Conclusions: It was possible to theoretically obtain the grain mean transport velocities through a screening device in elliptical motion by modifying the formula of the grain mean transport velocities used in linear motion.

The Isoinertial Assessment of Lumbar Function in Patients with Chronic Low Back Pain (등저항성삼축동력계(Isostation B-200)를 이용한 만성 요통 환자들의 요추부 기능)

  • Bae, Sung-Il
    • Journal of Korean Physical Therapy Science
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    • v.11 no.1
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    • pp.14-19
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    • 2004
  • Objective : This study obtained normative values for variable parameters of lumbar function with the isoinertial triaxial dynamometer in patients with chronic low back pain. Subjects and Methods : 30 patients(male 15, female 15) with chronic low back pain in this study. Variable parameters that were measured with the Isostation B-200 were lumbar range of motion, isometric maximum torques, and maximum velocities in three axis. Results : In patient male group mean R.O.M. was $82.9{\pm}12.5$ degrees in lumbar rotation, $76.5{\pm}17.1$ degrees in lumbar flexion/extension, and $64.3{\pm}14.5$ degrees in lumbar lateral flexion. In patient female group mean R.O.M. was $78.4{\pm}18.5$ degrees in lumbar rotation, $71.7{\pm}20.4$ degrees in lumbar flexion/extension, and $63.2{\pm}14.4$ degrees in lumbar lateral flexion. In patient male group mean isometric maximum torques was $64.7{\pm}23.8ft-lbs$ in lumbar rotation, $81.1{\pm}42.0ft-lbs$ in lumbar flexion, $122.2{\pm}43.6ft-lbs$ in lumbar extension, and $101.0{\pm}37.0ft-lbs$ in lumbar lateral flexion. In patient female group mean isometric maximum torques was $41.9{\pm}9.2ft-lbs$ in lumbar rotation, $49.9{\pm}23.9ft-lbs$ in lumbar flexion, $90.1{\pm}26.8ft-lbs$ in lumbar extension, and $62.0{\pm}16.7ft-lbs$ in lumbar lateral flexion. In patient male group mean maximum velocity of isoinertial exercise with low (25%) resistance was $102.4{\pm}28.8deg/sec$ in lumbar rotation, $108.9{\pm}32.2deg/sec$ in lumbar flexion/extension, and $103.5{\pm}30.4deg/sec$ in lumbar lateral flexion. In patient female group mean maximum velocity of isoinertial exercise with low (25%) resistance was $84.1{\pm}24.4deg/sec$ in lumbar rotation, $93.2{\pm}32.9deg/sec$ in lumbar flexion/extension, and $98.5{\pm}33.7deg/sec$ in lumbar lateral flexion. In patient male group mean maximum velocity of isoinertial exercise with high (50%) resistance was $74.0{\pm}20.9deg/sec$ in lumbar rotation, $98.7{\pm}32.8deg/sec$ in lumbar flexion/extension, and $85.0{\pm}25.8deg/sec$ in lumbar lateral flexion. In patient female group mean maximum velocity of isoinertial exercise with high (50%) resistance was $67.3{\pm}26.4deg/sec$ in lumbar rotation, $82.5{\pm}31.0deg/sec$ in lumbar flexion/extension, and $79.7{\pm}23.9deg/sec$ in lumbar lateral flexion. Conclusion : Maximum isoinertial velocities were more reliable and more significant than isometric maximum torque for the objective assessment of chronic low hack pain.

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A Study on Shipments of Swimming Crab Using Negative Binomial Regression Model (음이항회귀모형을 이용한 꽃게 출하량에 관한 연구)

  • Nam, Yeongeun;Seo, Jihyun;Choi, Gayeong;Lee, Kyeongjun
    • Journal of the Korean Data Analysis Society
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    • v.20 no.6
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    • pp.2941-2951
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    • 2018
  • The purpose of this paper is to analyse the effect of ocean weather factors on shipments of swimming crab. We use the data of data portal and ocean weather factors (mean wind velocity, mean atmospheric pressure, mean relative humidity, mean air temperature, mean water temperature, mean maximum wave height, mean significant wave height, maximum significant wave height, maximum wave height, mean wave period, maximum wave period). We did statistical analysis using Poisson regression analysis and negative binomial regression analysis. As the result of study, important factors influential in the shipments of swimming crab turn out to be mean wind velocity, mean atmospheric pressure, mean relative humidity, mean water temperature, maximum wave height, mean wave period and maximum wave period. the shipments of swimming crab increases as mean wind velocity, mean atmospheric pressure, mean relative humidity, mean water temperature increases or mean wave period increase. However, as maximum wave height, maximum wave period decreases, the shipment of swimming crab increases.

Comparative study of analytical models of single-cell tornado vortices based on simulation data with different swirl ratios

  • Han Zhang;Hao Wang;Zhenqing Liu;Zidong Xu;Boo Cheong Khoo;Changqing Du
    • Wind and Structures
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    • v.36 no.3
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    • pp.161-174
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    • 2023
  • The analytical model of tornado vortices plays an essential role in tornado wind description and tornado-resistant design of civil structures. However, there is still a lack of guidance for the selection and application of tornado analytical models since they are different from each other. For single-cell tornado vortices, this study conducts a comparative study on the velocity characteristics of the analytical models based on numerically simulated tornado-like vortices (TLV). The single-cell stage TLV is first generated by Large-eddy simulations (LES). The spatial distribution of the three-dimensional mean velocity of the typical analytical tornado models is then investigated by comparison to the TLV with different swirl ratios. Finally, key parameters are given as functions of swirl ratio for the direct application of analytical tornado models to generate full-scale tornado wind field. Results show that the height of the maximum radial mean velocity is more appropriate to be defined as the boundary layer thickness of the TLV than the height of the maximum tangential mean velocity. The TLV velocity within the boundary layer can be well estimated by the analytical model. Simple fitted results show that the full-scale maximum radial and tangential mean velocity increase linearly with the swirl ratio, while the radius and height corresponding to the position of these two velocities decrease non-linearly with the swirl ratio.

Probability distribution and statistical moments of the maximum wind velocity

  • Schettini, Evelia;Solari, Giovanni
    • Wind and Structures
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    • v.1 no.4
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    • pp.287-302
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    • 1998
  • This paper formulates a probabilistic model which is able to represent the maximum instantaneous wind velocity. Unlike the classical methods, where the randomness is circumscribed within the mean maximum component, this model relies also on the randomness of the maximum value of the turbulent fluctuation. The application of the FOSM method furnishes the first and second statistical moments in closed form. The comparison between the results herein obtained and those supplied by classical methods points out the central role of the turbulence intensity. Its importance is exalted when extending the analysis from the wind velocity to the wind pressure.