• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.546-553
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• 2022

Narrow rectangular channels are employed in nuclear research reactors that use plate-type nuclear fuels, high heat-flux compact heat exchangers, and high-performance micro-electronics cooling systems. Two-phase flow in narrow rectangular channels is important, and it needs to be better understood because it is considerably different than that in round tubes. In this study, mechanistic models were developed for the flow regime transition criteria for various flow regimes in co-current air-water two-phase flow for vertical downward flow inside a narrow rectangular channel. The newly developed criteria were compared to a flow regime map of downward air-water two-phase flow inside a narrow rectangular channel with a 2.35-mm gap width under ambient temperature and pressure conditions. Overall, the proposed model showed good agreement with the experimental data.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.6
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• pp.1220-1227
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• 2001

The condensation pressure drop fur refrigerant R-22 flowing in the plate and shell heat exchanger were investigated experimentally in this study. Two vertical counterflow channels were formed in the exchanger by three plates of commercial geometry with a corrugated trapezoid shape of a chevron angel of $45^{\circ}$. The condensing R-22 flowing down in one channel exchanges heat with the cold water flowing up in the other channel. The effects of the mean vapor quality, mass flux, average imposed heat flux and system pressure of R-22 on the pressure drop were explored in detail. The quality change of R-22 between the inlet and outlet of the refrigerant channel ranges from 0.03 to 0.05. The present data showed that pressure drop increases with the vapor quality. At a higher mass flux, pressure drop is higher for the entire range of the vapor quality. Also, a rise in the average imposed heat flux causes an slight increase in the Pressure drop. Finally, at a higher system pressure the pressure drop is found to be slightly lower. Correlation is also provided for the measured pressure drops in terms of the friction factor.

• Journal of Korean Society of Steel Construction
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• v.24 no.3
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• pp.245-256
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• 2012

The objective of this study is to investigate the effect of the openings on the structural behavior of SC walls. The test parameters were with or without the reinforcing of openings and sleeve thickness. The common failure showed that the crack in the concrete progressed with the plate's local buckling between the shear connectors. The failure of the openings showed that the vertical wall of the sleeve buckled toward the opening inside. The plate buckling load showed a similar value with or without the sleeve of the opening, respectively. However, the maximum compressive strength of the specimen without the opening was higher than that of specimen with the opening.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.9 s.114
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• pp.949-957
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• 2006

In this Paper, reduction of noise and vibration in ship cabins by using floating floor is studied. Two theoretical models are presented and predicted insertion losses of floating floor are compared to experimental results, where measurements have been done in mock-up built for simulating typical ship cabin structures. In ships, mineral wool is usually used as the impact absorbing materials. The first model (M-S-Plate Model) is that upper plate and mineral wool are assumed as a one-dimensional mass-spring system, which is in turn attached to the simply supported elastic floor. The second model (Wave-Plate Model) is that mineral wool is assumed as an elastic medium for wave propagation. The comparisons show that M-S-Plate model is in good agreement with experimental results when density of mineral wool is 140K, and fiber direction is horizontal. For higher density and vertical fiber direction, Wave-Plate model shows good agreements with measurements. It is found that including the elastic behavior of the floor is essential in improving accuracy of the prediction for low frequency ranges below $100{sim}200Hz$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.181-182
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• 2006

When a water jet is injected on the body surface, the pressure and shear stress on the surface are important physical parameters in determining the body surface wash out and physical stimulus. We used the force plate in order to measure the surface average pressure for different nozzle types and distances between a nozzle and a plate. We used the nozzles with a hole dimeter of 1.8, 2.9, 3.2mm, and the shower heads with 10 holes (hole diameter, 1mm) and 20 holes (hole diameter, 1mm). The distances between a nozzle and a plate was 10, 20, 30, 40cm. The results showed that the surface forces were not affected by the distances between a nozzle and a plate. Further numerical studies will be performed to predict wall shear stress based on the measured pressure data.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.92-101
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• 1993

This paper describes algorithms to extract license plates in vehicle images. Conventional methods perform preprocessing on the entire vehicle image to produce the edge image and binarize it. Hough transform is applied to the binary image to find horizontal and vertical lines, and the license plate area is extracted using the charateristics of license plates (the boundary information of license plates). Problems with this approach are that real-time processing is not feasible due to long processing time and that the license plate area is not extracted when lighting is irregular such as at night or when the plate boundary does not show up in the image. This research uses the gray level transition characteristics of license plates to verify the digit area by examining the digit width and the gray level difference between the background area the digit area, and then extracts the plate area by testing the distance between the verified digits. This research solves the probelm of failure in extracting the license plates due to degraded plate boundary as in the conventional methods and resolves the provlem of the time requirement by processing in real time such that practical application is possible.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.365-375
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• 2006

The HR Plates made hot rolled coils is lower than general structural steel plates in price. No difference between general steel plates and HR Plates with thickness up to 22mm are found in most characters such as cutting operation, fabrication and even welding. It can be concluded that HR Plates with thickness up to 22mm can be applied to flanges and webs of any girders as well as longitudinal ribs, longitudinal and vertical stiffeners of steel bridges appropriately. To increase the demand of HR Plates with thickness up to 22mm, it is necessary that HR Plates is applicable to full member in steel bridge including main girder.In this study, availabilities of the narrow steel box girder of light railway transit with HR Plate width as a main member are discussed. For application of HR Plate to steel bridge with 50m span or more, new support systems in three types are presented. Computational analysis is performed in 15 bridge models of light railway transit with beam element and plate element. As a analysis results, three models in light railway transit are presented. We finally come to the conclusion that HR Plates can be apply to narrow steel box girder in the light railway transit.

• Geomechanics and Engineering
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• v.13 no.5
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• pp.825-844
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• 2017

This study aimed to find out the pullout capacity of inclined strip anchor plate embedded in anisotropic and nonhomogeneous fully saturated cohesive soil in undrained condition. The ultimate pullout load has been found out by using numerical lower bound finite element analysis with linear programming. The undrained pullout capacity of anchor plate of width B is determined for different embedment ratios (H/B) varying from 3 to 7 and various inclination of anchor plates ranging from $0^{\circ}$ to $90^{\circ}$ with an interval of $15^{\circ}$. In case of anisotropic fully saturated clay the variation of cohesion with direction has been considered by varying the ratio of the cohesion along vertical direction ($c_v$) to the cohesion along horizontal direction ($c_h$). In case of nonhomogeneous clay the cohesion of the undrained clay has been considered to be increased with depth below ground surface keeping $c_v/c_h=1$. The results are presented in terms of pullout capacity factor ($F_{c0}=p_u/c_H$) where $p_u$ is the ultimate pullout stress along the anchor plate at failure and $c_H$ is the cohesion in horizontal direction at the level of the middle point of the anchor plate. It is observed that the pullout capacity factor increases with an increase in anisotropic cohesion ratio ($c_v/c_h$) whereas the pullout capacity factor decreases with an increase in undrained cohesion of the soil with depth.

• Wind and Structures
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• v.27 no.5
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• pp.311-324
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• 2018

This work examines vibration and bending response of carbon nanotube-reinforced composite plates resting on the Pasternak elastic foundation. Four types of distributions of uni-axially aligned single-walled carbon nanotubes are considered to reinforce the plates. Analytical solutions determined from mathematical formulation based on hyperbolic shear deformation plate theory are presented in this study. An accuracy of the proposed theory is validated numerically by comparing the obtained results with some available ones in the literature. Various considerable parameters of carbon nanotube volume fraction, spring constant factors, plate thickness and aspect ratios, etc. are considered in the present investigation. According to the numerical examples, it is revealed that the vertical displacement of the plates is found to diminish as the increase of foundation parameters; while, the natural frequency increase as the increment of the parameters for every type of plate.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.05a
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• pp.183-189
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• 2004