• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.337-342
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• 1996

The pool-boiling critical heat flux (CHF) of water on small flat plates has been experimentally investigated focusing on the effects of the inclination angle and size of the heated surface under near atmospheric pressure. The second-phase experiment was accomplished to find out the general CHF behavior for over-all inclination angles from -90$^{\circ}$ to 90$^{\circ}$using two plate-type test sections (30$\times$150 mm and 40$\times$150 mm) submerged in a slightly subcooled water pool. Test results generally confirm the first-phase findings and show little effect of inclination angle for inclined upward-facing cases. CHF position moves to lower position with the increase of the heater characteristic size and inclination angle(from -30$^{\circ}$to 60$^{\circ}$).

• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.459-477
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• 2012

This paper attempts to determine the inclination of the compression strut within variable angle truss models for RC beams loaded in shear-flexure through a proposed semi-analytical approach. A truss unit is used to analyze a reinforced concrete beam, by the principle of virtual work under the truss analogy. The inclination of the compression strut is then theoretically derived. The concrete contribution is addressed by utilizing the compatibility condition within each truss unit. Comparisons are made between the predicted and published experimental results of the seventy one RC beams with respect to the shear strength and the inclined angle of the compression strut at this state to investigate the adequacy of the proposed semi-analytical approach.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.185-188
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• 2015

An experimental study on downwardly and upwardly spreading flames over slanted electrical wire, which is insulated by Polyethylene(PE), was conducted with applied AC electric field. The result showed that downwardly and upwardly spreading flames with angle of inclination leaned toward burnt side and unburned side, respectively. With applied AC electric fields, size of downwardly spreading flame decreased slightly and that of upwardly spreading flame increased significantly. Flame spread rate showed various trends in terms of inclination, applied voltage and frequency.

• Journal of the Korean Society for Nondestructive Testing
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• v.4 no.1
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• pp.11-22
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• 1984

In the straight beam inspection of ultrasonic wave, the method for evaluating flaw size by AVG diagram is useful as a method for the quantitative evaluation of results of ultrasonic flaw detection. This study was carried out the measure the size of circular flat flaw with the inclination by straight beam inspection and could be decreased the error of application due to the inclination of flaw by AVG diagram in consideration of correction coefficient. From the result of the experiment, the error by means of the application of experimental values to AVG diagram was increased as the inclination angle grows. Also, it n s increased the error of application as the detecting frequency and diameter of flaw grows in the same inclination angle. In case of diameter of flaw 6mm, AVG diagram could be applied to the inclination angle $3^{\circ}$ for 5 MHz, $7^{\circ}$ for 2.25 MHz, $15^{\circ}C$ for 1 MHz in the range of 20% error and the theory was concided with the experiment to $5^{\circ}C$ for 5 MHz, $10^{\circ}C$ for 2.25 MHz, $15^{\circ}C$ for 1 MHz in the range of 10% error by correction eq. (45) due to the inclination angle. Therefore, it is considered that the results obtained from this study will be somewhat helpful informations for the size evaluation of circular flat flaw with the inclination.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1269-1279
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• 2023

Pool boiling experiments are performed within an isolated bubble regime at inclination angles of 0° and 45°. When a bubble grows and departs from the heating surface, the pressure, buoyancy, and surface tension force play important roles. The curvature and base diameter are required to calculate the pressure force, the bubble volume is required to calculate the buoyancy force, and the contact angle and base diameter are required to calculate the surface tension force. The contact angle, base diameter, and volume of the bubbles are evaluated using images captured via a high-speed camera. The surface tension force equation proposed by Fritz is modified with the contact angles obtained in this study. When the bubble grows, the contact angle decreases slowly. However, when the bubble departs, the contact angle rapidly increases owing to necking. At an inclination angle of 0°, the contact angle is calculated as 82.88° at departure. Additionally, the advancing and receding contact angles are calculated as 70.25° and 82.28° at departure, respectively, at an inclination angle of 45°. The dynamic behaviors of bubble growth and departure are discussed with forces by pressure, buoyancy, and surface tension.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1623-1628
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• 2004

Recently mini-channels or micro-channels are widely used for cooling the high density power electronic devices. Especially, the channels are used in small and high efficient equipments such as heat pipes and heat exchangers. Interfacial velocities between liquid and gas phases are very important in mini or micro-channels. In this paper, an experiment and a numerical analysis on the interfacial velocities were performed. In the experiment, the interfacial velocities which were measured by the high-speed CCD camera were about $26{\sim}33$ cm/s and the velocities increased as the inclination angle did. In the numerical experiment, CFD-ACE+, a commercial program, was used, the velocities had similar values with experimental results. As the inclination angle and the contact angle increased, the interfacial velocities did because of the surface tension which causes to move the interface. The effect of inclination angle was larger in the converging channels than in straight channels.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.3
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• pp.320-327
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• 2002

An experimental study of heat transfer from hot flat surface to water sprays was conducted in high temperature region. Heat transfer measurements for hot flat surface were made by 4 sheathed C-A thermocouples. Droplets volume flux were also measured-independently at a position in spray field. The test conditions included variations in droplets volume flux, subcooling of cooling water of $1.565\times10^{-3} to 14.089\times10^{-3}m^3/m^2s and 80 to $20^{\circ}C$ respectively. The effects of inclination angle on heat transfer were investigated and changes in inclination angle of hot flat surface affected heat transfer coefficients of high temperature region.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2233-2238
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• 2003

It is well known that organized vortex rotations swirl and tumble greatly affect the mixing, the combustion and heat transfer processes in engine cylinder. We have developed 3 dimensional numerical simulation codes whose predictions make good agreement with the experimental data. Large eddy simulation based on Smagorinsky subgrid scale model was adopted to describe the turbulence of in-cylinder flows. The tumble motions generated by different inclination angles between valve-port and cylinder head have been calculated. The results show that the angles between direction of induced flow and cylinder walls which the flow collides with play a great role in the formation and generation of tumble motions. Therefore, it is inferred that seat angle and inclination angle are important factors of engine design. In addition, the numerical results of different engine speed -1000 rpm and 3000 rpm are very similar in the flow structure.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.38-44
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• 2002

An experimental investigation was performed to observe the cooling performance of cutting oil and the effect of inclination angle on the transport behaviour of a inclined thermosyphons with low integral-fins. Relatively high rates of heat transfer have been achieved by operating this manner. Water has been used as the working fluid. The inclimation angle of thermoryphon and the ratio of Reynolds number of cooling to hot fluid have been used as the experimental parameters. Heat transfer coefficients at the condenser and the evaporator are estimated from experimental results. The experimental results have been assessed and compared with existing theory. Good agreement with the theory of Yiwei has been found. The maximum heat flow rate in the thermosyphon proved to depend upon the inclination angle.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.9
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• pp.698-706
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• 2006

Experiment and numerical calculation have been peformed to investigate mixed convection heat transfer between inclined parallel plates. Particle image velocimetry (PIV) with thermo-sensitive liquid crystal (TLC) tracers is used for visualizing and analysis. This method allows simultaneous measurement of velocity and temperature fields at a given instant of time. Quantitative data of the temperature and velocity are obtained by applying the color-image processing to a visualized image, and neural network is applied to the color-to-temperature calibration. The governing equations are discretized using the finite volume method. The results are presented for the Reynolds number ranges from 0.004 to 0.062, the angle of inclination, ${\Theta}$, from 0 to 45 degree and Prandtl number of the high viscosity fluid is 909. The results show velocity, temperature and mean Nusselt numbers distributions. It is found that the periodic flow of mixed convection between inclined parallel plates is shown at $0^{\circ}{\leq}{\Theta}<30^{\circ}$, Re<0.062, and the flow pattern can be classified into three patterns which depend on Reynolds number and the angle of inclination. The minimum Nusselt numbers occur at Re=0.05 regardless of the angle of inclination.