• 한국물환경학회지
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• 제25권6호
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• pp.896-901
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• 2009

In this study, in order to apply the air and pure oxygen in the Jet Loop Reactor (JLB) in which the oxygen transfer rate is high, differentiate the operation mode according to each air flowrate and liquid flowrate and investigate the oxygen transfer characteristic, an experiment was carried out. The oxygen concentration with the air flowrate ($Q_g$) and liquid flowrate ($Q_L$) was identical but the oxygen transfer coefficient ($K_L{\cdot}a$) is linear depending on degree of two factors. The width of an increase is small in $0.1min^{-1}$ when the air flowrate is 0.2 L/min with increasing the liquid flowrate. Whereas, the increment was exposed to be very high for $1.5min^{-1}$ when the air flowrate was 5 L/min. In the experiments using the pure oxygen, it was 30 mg/L of oxygen concentration finally and it was 3.5 times than using the air. But the time reached the saturated concentration was similar to using the air, and $K_L{\cdot}a$ was similar to using the air too. Analysis between two independent variable and oxygen transfer of the correlation is the same model like $K_L{\cdot}a={0.0161Q_L}^{1.5371}{Q_g}^{0.5433}$ using with coefficient non linear regression analysis. It was resulted that the liquid flowrate were approximately three times than air flowrate on effect to oxygen transfer rate.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1712-1717
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• 1991

The paper describes estimation errors of unsteady flowrate measurements due to parameter changes in a quasi-remote instantaneous flowrate measurement method (abbreviate as QIFM) and an instantaneous flowrate measurement method using two points pressure measurements (abbreviate as TPFM). By introducing error performance index, the influence of parameter changes on the accuracy, and dynamic response of the estimated unsteady flowrate are evaluated. Of four parameters, the variation of the length of the pipeline and speed of sound produce large errors in the estimated unsteady flowrate during transient periods. The effect of kinematic viscosity of the working fluid(oil) is relatively insensitive in unsteady flowrate estimation.

• 한국가스학회지
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• 제1권1호
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• pp.101-105
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• 1997

LPG 지하저장기지에서 클로깅 현상이 발생할 경우 저장공동 주위의 지하수위가 설계된 수치보다 낮아져 저장물이 누출되므로 이에 대한 감지가 필수적이라 할 수 있다. 따라서 본 연구에서는 클로깅 현상이 실제로 발생하였을 경우 저장기지에서 관측할 수 있는 관측인자인 공동주변 지하수위, 수벽공 주입수량, 공동 삼출수량들의 변화양상을 고찰하기 위하여 지하저장기지를 모사한 모형실험장비를 제작하여 각 인자들의 변화 측정실험을 수행하였다. 클로깅 발생시 관측인자의 변화양상은 다음과 같다. 지하수위는 공동의 압력이 커짐에 따라 증가하고 클로깅이 심할수록 감소하는데, 클로깅 발생을 지하수위 변화에 의해서 보다 잘 감지하려면 공동의 압력을 가능한 낮게 하고, 공동 운영 초기의 지하수위와 현재 운영 상태의 지하수위를 비교해 보는 것이 바람직하다. 클로깅에 의한 지하수위의 감소는 수벽공의 압력이 커질수록 다소 둔화된다 현탁물질에 의한 클로깅이 심할수록 주입수량과 삼출수량은 선형적으로 감소하는데 주입수량의 감소율이 삼출수량의 감소율보다 크게 나타난다.

• 대한기계학회논문집A
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• 제27권5호
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• pp.779-788
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• 2003

This study evaluates the approximation errors of the existing linearized equation for a servovalve nonlinear flowrate characteristic. At first, the errors are evaluated on flowrate/pressure characteristics diagrams. Subsequently, they are investigated with time response simulation results for several hydraulic control systems. To enable systematic evaluation of computational error, the authors propose three kinds of equations with restructured forms of the existing linearized equation. As results of the evaluations, it is ascertained that comparatively good computational accuracy can be achieved with the existing linearized equation when both an operating point for the linearized equation and operating range of the hydraulic system stay near the flowrate axis of the flowrate/pressure characteristics diagram. In addition, the results show that comparatively big computational error may occur when operating range of a hydraulic system stay apart from the flowrate axis of the flowrate/pressure characteristics diagram.

• 설비공학논문집
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• 제4권2호
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• pp.116-122
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• 1992

The purpose of this paper is to determine the cut off flowrate regions of the overflow valve in using L.P gas vassels. The experimental methods were employed to measure the cut off flowrate in the state of constant pressure by using the $N_2$ gas. 1) To determine the optimum cut off flowrate regions, Hose length are required 0.5 meters. 2) Cut off fowrate regions about the each pressure can be suggested as follows. A) Cut off flowrate rigions are $2.0-4.0m^3/hr$ at the pressure of the $1Kg_f/cm^2$. B) Cut off flowrate rigions are$7.0-10.0m^3/hr$ at the pressure of the $10Kg_f/cm^2$.

• 대한기계학회논문집B
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• 제25권4호
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• pp.561-571
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• 2001

The standard uncertainty of flowrate measurement is obtained by combining that of independent variables. Gravimetric and volumetric method were applied to determine the flowrate and the standard uncertainties of flowrate measurement by both methods were evaluated in accordance with the procedure recommended by International Organization for Standardization. The combined standard uncertainties of determining the flowrate were estimated from the sensitivity coefficient and the standard uncertainty of independent variables. For practical application, the methods for evaluating and expressing uncertainty in flow measurement were discussed. It was found that the uncertainties of the weighing and time measurement in gravimetric method, the volume and time measurement in volumetric method have dominant influence on that of flowrate measurement. With the quantitative analysis of the sensitivity coefficient, the contribution of the each variable uncertainty to the combined standard uncertainty of flowrate measurement is shown clearly.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.614-625
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• 2004

The main purpose of this study is to get flowrate coefficient 'q' and to study characteristics of flowrate of screw pump. This study is based on Muskin's formula and depends on the computer simulation. The results of study are as follows. 1. Flowrate coefficient will reduce according to increase of inclination. The larger the pitch ratio is and the smaller the diameter ratio is, the more coefficient reduces. 2. As a rule, the coefficient increases according to reduction of the diameter ratio, but the coefficient tends to reduce when the ratio is less than 0.45. So, in actual application, it is recommended that the ratio should be above 0.45. 3. If the pitch ratio increases, the coefficient increases in case of small inclination and decreases in case of large inclination. 4. The coefficient increases according to number of windings. Especially, singles winding is not used in actual application because it has too small coefficient. 5. The coefficient decreases when the influent water level falls. Flowrate is almost zero when the water level is below $40\%$ of Filling Points.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.402-407
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• 2008

This study is performed to investigate heat transfer characteristics for thermal performance of fin-and-tube sensible heat exchangers under the low air flowrate according to fin geometry combination and coolant flowrate control. Fins and tubes of samples were separated between front row and rear row. Experiment results are plotted heat transfer rate of each row, heat transfer coefficient and sensible heat ratio against water flowrate control of each row. It is observed that thermal performance can be enhanced by fin geometry combination and water flowrate control of each row under the low air flowrate.

• 드라이브 ㆍ 컨트롤
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• 제17권2호
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• pp.28-37
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• 2020

It is difficult to analytically derive the relationship among volumetric displacement, flowrate, torque, and rotation speed regarding an instantaneous position of gerotor hydraulic pumps/motors. This can be explained by the geometric shape of the rotors, which is highly complicated. Herein, an analytical method for the instantaneous torque, rotation speed, flowrate, and volumetric displacement of a pump/motor is proposed. The method is based on two physical concepts: energy conservation and torque equilibrium. The instantaneous torque of a pump/motor shaft is determined for the posture of rotors from the torque equilibrium. If the torque equilibrium is combined with the energy conservation between the hydraulic energy of the pump/motor and the mechanical input/output energy, the formula for determining the instantaneous volumetric displacement and flowrate is derived. The numerical values of the instantaneous volumetric displacement, torque, rotation speed, and flowrate are calculated via the MATLAB software programs, and they are illustrated for the case in which inner and outer rotors rotate with respect to fixed axes. The degrees of torque fluctuation, speed fluctuation, and flowrate fluctuation can be observed from their instantaneous values. The proposed formula may provide a better understanding of the design or analysis process of gerotor pumps/motors.

• Journal of Advanced Marine Engineering and Technology
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• 제9권4호
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• pp.339-347
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• 1985

Precise measurement of flowrate is considered as an important measuring factor in mechanical and chemical experiment. Although there are many methods to measure flowrate, Float type flowmeter is widely used because of its easy attachment to piping and high measuring precision. To design the precise float type flowmeter, much design information such as tapered-tube dimensions, float size, float shape and float material is required. In this paper, fundamental design theory for float type flowmeter according to the given flowrate range is suggested and compensation coefficients of volumetric and weight flowrate for water, R-113 and air are calculated.