• Solar Energy
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• v.12 no.3
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• pp.70-83
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• 1992

The interaction between the surface radiation and the mixed convection transport from an isolated thermal source, with a uniform surface heat flux input and located in a rectangular enclosure, is stuied numerically. The enclosure simulates a practical system such an air cooled electric device, where an air-stream flows through the openings on the two vertical walls. The heat source represents an electric component located in such an enclosure. The size of this cavity is $0.1[m]{\times}0.1[m]$. The inlet velocity is assumed as 0.07[m/s] and the inlet temperature is maintained as $27^{\circ}C$. The inflow is kept at a fixed position. Laminar, two dimensional flow is assumed, and the problem lies in the mixed convection regime, governed by buoyancy force and surface readiation. The significant variables include the location of the out-flow opening, of the heat source and the wall emissivity. The basic nature of the resulting interaction betwwn the externally induced air stream and the buoyancy-driven flow generated by the source is investigated. As a result, the best location of the heat source to make the active heat transfer is 0.075[m] from the left wall on the floor. The trends observed are also discussed in terms of heat removal from practical systems such as electric circuitry.

• Korean Journal of Heritage: History & Science
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• v.45 no.2
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• pp.4-19
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• 2012

There remain many royal tombs of the Goryeo Dynasty in Gaeseong and Ganghwa. During the Goryeo Dynasty, these royal tombs were taken over tradition of tomb construction style from previous generation, and they completed their own inventive style. Furthermore they handed down those style to the Joseon Dynasty. The area of tomb was divided into 3 or 4 steps, and stone figures and T-shaped houses for sacrifice were arranged on each steps. It was the stone chamber of lateral opening style which had an entrance to southward, and it was formed as a rectangular box-shaped with a pile of stone walls and a flat ceiling. There was a coffin stand in the middle of floor, and traditional bricks were around them. The wall side and ceiling had been whitewashed and painted pictures. These are general characteristics for the tomb construction style of the Goryeo Dynasty. By the way, we can notice a number of features except those general things with inspection in detail. In early days, we confirmed 1step-parallel fulcrum ceiling, coffin stand of all in one stone, bier of burial artifact, and mural of plant material as a set, but they were changed as flat ceiling, Red-stone wall with rectangular stone, coffin stand set as stone pillar through the period of transitional form as of in the late 12th century. In case of several royal tombs, the fragments of king's epitaph which were confirmed from tombs could be defined owners clearly, and there were considerable timing difference between the large numbers of celadons which were excavated with the fragments of king's epitaph and recording chronologically of stone chamber structure. The reason for timing difference is that posterity artifacts were buried through repairing courses by occasion of destruction caused by robbing of the royal tombs. Meanwhile I inferred the existing hypothesis about owners of royal tombs and autonym ones in comparison the burial spot direction of hypothesis ones and outcomes of excavation. Therethrough, some hypothesis about owners of royal tombs such as Myung-neung which was assumed as tomb of the King Choongmok were not correct.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.468-477
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• 2019

The numerical model of Boussinesq approximation, which is mainly used for evaluating the port calmness due to the irregular waves, has a limit of applicability of lattice size in ports such as marinas with narrow port openings of around 30m. The SWASH model controls the partial reflection according to the depth, porosity coefficient and structure size when applying the reflected wave incident on the structure and terrain. In this study, the partial reflection evaluation at the front of the structure according to the bottom shape and the shape of the structure are examined. In order to evaluate the reproducibility of the model due to the diffraction waves entering the term, the area of incidence at right angles and inclination of the structure is constructed and compared with the diffraction theory suggested by Goda et al. (1978). The experimental results of the sectional structure reflectances calculated as the depth mean show reflectances similar to the approximate values of the reflectances presented by Stelling and Ahrens (1981). It is considered that the reflected wave is well reproduced according to the control of the reflected wave at the boundary and the shape and topography of the structure. Compared with previous studies to examine the diffraction of the wave incident from the breakwater opening, the wave incidence angle and the shape of the diffraction wave are very similar to the theoretical values, but both oblique and rectangular incidence In the case where the direction concentration is small, the diffraction degree is underestimated in some sections with the crest ratio of 0.5 to 0.6.