• Journal of Advanced Marine Engineering and Technology
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• v.22 no.6
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• pp.844-853
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• 1998

Natural and forced convection experiments were carried out in order to investigate the effects of channel spacing gap between protrusions and number of rows of protrusion, In natural convection the optimum channel spacing was found to be approximately 20mm regardless of the protrusion gaps. For optimum channel spacing the heat transfer coefficients were converged to an asymptotic value after the fourth row. The heat transfer coefficient for each row approaches to constant values for protrusion gaps larger than 10 mm. An experimental correlation has been suggested by using a modified Rayleigh number based on the dimensionless characteristic length(G/L). In forced convec-tion the heat transfer coefficients were not merged to an asymptote until the fifty row and increases as the channel spacing at the constant Reynolds number decreases.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.19-29
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• 2008

Underwater acoustic(UWA) communication is one of the most difficult field in terms of severe channel environments such as multipath propagation, high temporal and spatial variability of channel conditions. Therefore, it is important to model and analyze the characteristics of underwater acoustic channel such as multipath propagation, transmission loss, reverberation, and ambient noise. In this paper, UWA communication channel is modeled with a ray tracing method and applied to image transmission. Quadrature phase shift keying(QPSK) and multichannel decision feedback equalizer(DFE) are utilized as phase-coherent modulation method and equalization technique, respectively. The objective is to improve the performance of the image transmission using vertical sensor array instead of single sensor in the viewpoint of bit error rate(BER), constellation diagram, and received image quality.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.3
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• pp.198-206
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• 2008

A numerical study has been carried out to investigate heat transfer enhancement in channel flow using large-scale vortices. A square cylinder, inclined with respect to the main flow direction, is located at the center of the channel flow, generating a separation region and Karman vortices. Two cases are considered; one with a fixed blockage ratio and the other one with a fixed cylinder size. In both cases, the flow characteristics downstream of the cylinder significantly change depending on the inclination angle. As a result, heat transfer from channel wall is significantly enhanced due to increased vertical-velocity fluctuations induced by the large-scale vortices shed from the cylinder. Quantitative results as well as qualitative physical explanation are presented to justify the effectiveness of the inclined square cylinder as a vortex generator to enhance heat transfer from channel wall.

• Structural Engineering and Mechanics
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• v.56 no.2
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• pp.241-256
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• 2015

Channel girder bridges that consist of a deck slab and two side beams are good choices for railway bridges and urban rail transit bridges when the vertical clearance beneath the bridge is restricted. In this study, the behavior of simply supported channel girder bridges was theoretical studied based on the theory of elasticity. The accuracy of the theoretical solutions was verified by the finite element analysis. The global bending of the channel girder and the local bending of the deck slab are two contributors to the deformations and stresses of the channel girder. Because of the shear lag effect, the maximum deflection due to the global bending could be amplified by 1.0 to 1.2 times, and the effective width of the deck slab for determining the global bending stresses can be as small as 0.7 of the actual width depending on the width-to-span ratio of the channel girder. The maximum deflection and transversal stress due to the local bending are obtained at the girder ends. For the channel girders with open section side beams, the side beam twist has a negligible effect on the deflections and stresses of the channel girder. Simplified equations were also developed for calculating the maximum deformations and stresses.

• Journal of Korea Society of Digital Industry and Information Management
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• v.20 no.1
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• pp.133-147
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• 2024

In this study, we examine the components and characteristics of channel brands, the renewal process of channel brands, and the competitiveness of SBS Subusu News and MBC 14F, online channels of Korea's leading terrestrial broadcasting company. We conducted in-depth interviews with staffs YouTube news channels such as Subusu News and 14F. First, examining the brand components and characteristics of SBS's Subusu News and MBC's 14F vertical channel, Subs News maintained its direction through the renewal of the logo type, graphic characterization, emoticon production, and campaign design production. 14F focused on brand renewal of the logo type and modification of thumbnail design to reveal the identity of the channel brand. Subusu News and 14F have achieved success through a spin-off approach that considers content relevance, expanding their brand extension. As a result of analyzing the competitiveness of the channel brand, Subusu News maintained its identity as a combination of B-class sensibility and journalism, while 14F positioned itself as a channel that delivers useful information content.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.83.3-84
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• 2008

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.40.2-40.2
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• 2008

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.65.2-65.2
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• 2008

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.114-114
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• 2002

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.479-480
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• 2006