• 한국해양학회지
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• v.29 no.3
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• pp.296-303
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• 1994

Rotating right cylinder of rigid sloping boundaries(top-bottom) is filled with two-layered fluid. External fluid which has the same density as the lower-layer is pumped through the rim boundary at the bottom, and this induces uniform vertical velocity in the interior that produces the Sverdrup type motion such as southward flowing western boundary current with northward interior horizontal motion. The rigid sloping upper boundary meets with lower layer to simulate so called "polar front", and the upper-layer motion influenced by the lower-layer flow has been observed. Barotropic motion in the western part of the basin while baroclinic motion in the eastern half is always present. In particular, both southward flowing eastern boundary flow and western boundary flow meets near the western wall and it induces northward western boundary flow to separate from the boundary With increased ${\beta}$-effect on the upper0layer the width of western boundary decreases and the separated western boundary flow moves into the interior to form an eddy-like motion. Baroclinic Rosebay wave clearly observed in the easter boundary slowly propagates to the west but it seems to be decayed before travelling to the western boundary. A local topograpic effect imposed on the lower-layer causes very sensitive response of upper layer boundary flows. In the east standing0wave0like features are observed in the west whereas the width of the boundary increases without any evidence of the separation of the western boundary flow.This may be due to the gact that even the lower-lauer barotropic motion feels the topography its influence does not propagate into the upper-layer. With large ${\beta}$-effect on the upper-layer,relatively large scale waves whose wavelengths are greater than the internal radius deformation exist in the interior.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.419-426
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• 2004

A three-dimensional computation was conducted to understand effects of the inlet boundary layer thickness on the loss mechanism in a low-speed axial compressor operating at the design condition(${\phi}=85\%$) and near stall condition(${\phi}=65\%$). At the design condition, the flow phenomena such as the tip leakage flow and hub comer stall are similar independent of the inlet boundary layer thickness. However, when the axial compressor is operating at the near stall condition, the large separation on the suction surface near the casing is induced by the tip leakage flow and the boundary layer on the blade for thin inlet boundary layer but the hub corner stall is enlarged for thick inlet boundary layer. These differences of internal flows induced by change of the boundary layer thickness on the casing and hub enable loss distributions of total pressure to be altered. When the axial compressor has thin inlet boundary layer, the total pressure loss is increased at regions near both casing and tip but decreased in the core flow region. In order to analyze effects of inlet boundary layer thickness on total loss in detail, using Denton's loss models, total loss is scrutinized through three major loss categories in a subsonic axial compressor such as profile loss, tip leakage loss and endwall loss.

• Journal of the Korean Geographical Society
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• v.33 no.1
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• pp.41-56
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• 1998

The main purpose of this study is to delimit the boundary of central business district and to describe the internal structure of CBD in Seoul. To delimit the CBD boundary, we used the locational matrices of main CBD functions, which were ofganized through fieldworks. CBD functions are classified into 20 categories. They are retail sales, corporation managements, administration managements, business, and unclassified services, customer(personal)services, and manufacturings. The core area of CBD in Seoul is at Chongro and Chung Gu area that shows the locational consistency comparing to 1970s. Although the boundary is slightly expanded into west, south and east, the extent of horizontal expansion in CBD can be negligible comparing to the remarkable growth of Korean economy after 1970s. The reasons why CBD showed little expansion can be found out from the process of restructuring in Seoul metropolitan area, such as the growth of subcenters, decentralization of central functions, construction of highrise buildings, redevelopment in central area and so on. Internal structure of Seoul's CBD shows 5 specialized functional subdistricts. They are CBD core area, subdistrict of department and office functions, retail sales, customer services and light manufacturings.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 1994.10a
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• pp.25-25
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• 1994

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.404-405
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• 2005

• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.341.1-341
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• 1999

• The Journal of the Acoustical Society of Korea
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• v.31 no.3
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• pp.142-150
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• 2012

The waveguide finite element (WFE) method is a useful numerical technique to investigate wave propagation along waveguide structures which have uniform cross-sections along the length direction ('x' direction). In the present paper, the vibration and radiated noise of the submerged pipe with fluid is investigated numerically by coupling waveguide finite elements and wavenumber boundary elements. The pipe and internal fluid are modelled with waveguide finite elements and the external fluid with wavenumber boundary elements which are fully coupled. In order to examine this model, the point mobility, dispersion curves and radiated power are calculated and compared for several different coupling conditions between the pipe and internal/external fluids.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.2
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• pp.127-153
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• 2012

This paper presents an advanced computational method for the prediction of the responses in the frequency domain of general linear dissipative structural-acoustic and fluid-structure systems, in the low-and medium-frequency domains and this includes uncertainty quantification. The system under consideration is constituted of a deformable dissipative structure that is coupled with an internal dissipative acoustic fluid. This includes wall acoustic impedances and it is surrounded by an infinite acoustic fluid. The system is submitted to given internal and external acoustic sources and to the prescribed mechanical forces. An efficient reduced-order computational model is constructed by using a finite element discretization for the structure and an internal acoustic fluid. The external acoustic fluid is treated by using an appropriate boundary element method in the frequency domain. All the required modeling aspects for the analysis of the medium-frequency domain have been introduced namely, a viscoelastic behavior for the structure, an appropriate dissipative model for the internal acoustic fluid that includes wall acoustic impedance and a model of uncertainty in particular for the modeling errors. This advanced computational formulation, corresponding to new extensions and complements with respect to the state-of-the-art are well adapted for the development of a new generation of software, in particular for parallel computers.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2939-2948
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• 2020

This paper presents an analytic solution procedure of the rotationally restrained hinged-hinged beam subjected to transverse motions at supports based on EBT (Euler-Bernoulli beam theory). The EBT solutions are compared with the solutions based on TBT (Timoshenko beam theory) for a wide range of the rotational restraint parameter (kL/EI) of slender beams whose slenderness ratio is greater than 100. The comparison shows the followings. The internal loads such as bending moment and shearing force of an extremely thin beam obtained by EBT show a good agreement with those obtained by TBT. But the discrepancy between two solutions of internal loads tends to increase as the slenderness ratio decreases. A careful examination shows that the discrepancy of the internal loads originates from their dynamic components whereas their static components show a little difference between EBT and TBT. This result suggests that TBT should be employed even for slender beams to consider the rotational effect and the shear deformation effect on dynamic components of the internal loads. The influence of the parameter on boundary conditions is examined by manipulating the spring stiffness from zero to a sufficiently large value.

• Asia Marketing Journal
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• v.16 no.4
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• pp.19-37
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• 2015

Forming interfirm collaborative relationships has become a key aspect of a firm's marketing strategies to create value for customers and achieve greater firm performance. While empirical findings are mixed in previous studies, this study is an effort to identify boundary conditions for the benefits of marketing alliances. We investigate internal and environmental factors that may magnify or constrain the effect of marketing alliances on firm profitability. Given the complementary relationship between marketing and R&D activities, we focus on a firm's R&D intensity as an internal factor that may magnify the value of marketing alliances for firm performance. For environmental factors, we focus on industry turbulence and industry competitiveness. Industry turbulence refers to the degree to which industry market conditions change quickly and unpredictably, whereas industry competitiveness refers to the degree to which a firm faces competition in the industry. By testing these factors, we are intended to reveal boundary conditions that determine the value of marketing alliances for firm profitability. The analysis of firms in the diverse industries shows that while the main effect of marketing alliances on firm profitability is not significant, it becomes more positive when R&D investment is more intensive or when industry environment is more turbulent. The results of this study imply that just forming more marketing alliances may not be enough to increase firm profitability. Our findings imply that marketing alliances become more effective in a dynamically changing industry environment. That is, firms can cope with industry uncertainties more effectively by forming marketing alliances. At the same time, the moderating effect of R&D intensity implies that the internal investments in R&D magnify the effect of marketing alliances on firm profitability. The findings of this study contributes to the existing alliance literature in three aspects. First, this study enhances our understanding of the contingent value of marketing alliances by testing both internal and external factors that may influence the effectiveness of marketing alliances. Second, this study responds to the need for research that investigates actual performance resulting from interfirm relationships. Third, while previous studies primarily focused on a specific industry, this study extend previous findings of the boundary conditions for the benefits of marketing alliances in a broader context.