• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.633-635
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• 2018

The compensation characteristics of the distorted WDM channels compensated for by dispersion management (DM) and optical phase conjugation in the long-haul (50 fiber spans ${\times}$ 80 km) transmission link with the randomly distributed single mode fiber (SMF) length and residual dispersion per spans (RDPS) are investigated as a function of the arrangement of SMF and dispersion compensating fiber (DCF) and the control position of net residual dispersion (NRD).

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.117-122
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• 2003

Cheongdam Bridge in Seoul Metropolitan Subway Line No.7 recently constructed has 180 meters (2@90m) of expansion length of structure (distance between fixed points). Track type is all ballasted track and rail expansion joint is installed at every movable point. However, there is no expansion joint at the transition area between ballasted track ,end deck. By this reason, the rail buckling has been occurred every year and there is actually an abnormal behavior in expansion. In this study, based on the modeling of the Cheongdam Bridge, the element of interacting relationship between track and structure which is influential to track displacement in long-span bridge was analyzed and, finally, the methodology to ensure the continuous-welded rail in Cheongdam Bridge was suggested.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.195-201
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• 1996

This paper is mainly forcused on the application of modal analysis In analyze the geometrically non-linear buckling behaviors of large span spatial structures, and the evaluation of each eigen mode affected post-buckling behaviors and buckling loads. Modal analysis is applied . to derivation of the system matrices transforming actual displacement space into generalized coordinates space represented by coefficients multiplied in the linear combination of eigen modes which are independent and orthogonal each other. By using modal analysis method, it will be expected to save the calculating time by computer extremely. For example, we can obtain the satisfactorily good results by using about 7% of total eigen modes only in case of single layer latticed dome. And we can decrease the possibility of divergence on the bifurcation point in the calculation of post-buckling path. Arc-length method and Newton-Raphson iteration method are used to calculate the nonlinear equilibrium path.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.213-216
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• 2005

A numerical analysis was performed for interior connections of continuous flat plate to analyze the effect of design parameters such as column section shape, gravity load and slab span on the behavioral characteristics of the connections. Through the parametric study, the variations of shear stress distribution around the connection were investigated. According to the result of numerical analysis, as the length of the cross section of column in the direction of lateral load increases and gravity load increases, the effective area and the maximum shear strength providing the torsional resistance decrease considerably. And as the slab span loaded with relatively large gravity load increases, the negative moment around the connection increases and therefore the strength of connection against unbalanced moment decreases.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.406-409
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• 2006

Serviceability resign is required to control the cracking at the joint of precast decks having longitudinal prestress in continuous composite bridges. Especially, details of twin girder bridges are complex not only due to main reinforcements and transverse prestress for the resign of long-span concrete slabs but also due to shear pockets for obtaining the composite action. This paper suggests the design guidelines for the magnitude of the effective prestress and for the selection of filling materials and their requirements in order to use precast decks for twin-girder continuous composite bridges. The necessary initial prestress was also evaluated through the long-term behavior analysis. From the analysis, existing design examples were revised and their effectiveness was estimated. When a filling material having bonding strength higher than the requirement is used in the region of high negative moment, uniform configuration of longitudinal prestressing steels along the whole span length of continuous composite bridges can be achieved resulting in simplification of details and enhancement of the construction costs.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.169-172
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• 2003

Time dependent deflections of double composite box girders are investigated based on the on going laboratory experiments scheduled for 3months long. Two of 2-span double composite box girders with 2.5m each span length are cast and time dependent behaviors are measured using 30 strain gages and 2 LVDTs after 5 days' curing. The measured experimental results are compared with the numerical predictions performed based on the one dimensional finite element method adopting beam element. The FEM formulation adopts the time dependent concrete constitutive model which is derived in an incremental format by expanding the total form of stress-strain relation by the first order Taylor series with respect to the reference time. A good agreement between the measured and predicted results are observed and the effects of the bottom concrete placed at the negative moment region of the bridge girder are discussed.

• Computers and Concrete
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• v.2 no.2
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• pp.147-164
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• 2005

This paper summarizes an experimental study on the seismic behavior of lower stories of a mid-rise reinforced concrete frame building. Two reinforced concrete frames with two stories and one span were tested and each frame represents lower two stories of an 11-story RC frame building. Both frames were designed in accordance with Japanese design guidelines and were identical except in the variation of axial force. The tests demonstrated that the overall load-displacement relations of the two frames were nearly the same and the first-story column shear was closely related to the column axial load. The columns and beams elongated during both of the tests, with the second-floor beam elongation exceeding 1.5% of the beam clear span length. The frame with higher axial loads developed more cracks that the frame under moderate axial load.

• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.73-80
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• 2009

A tidal current turbine is designed and analyzed numerically by using blade element momentum theory. The rated power has a limitation because the diameter of the tidal current turbine cannot exceed the depth of sea water. This study investigates a horizontal axis tidal-current turbine with a rated power of 500 kW. NACA-6 series laminar foil shape is used for basic airfoil along the blade span. The distributions of chord length and twist angle along the blade span are obtained from the hydrodynamic optimization procedure. Prandtl's tip loss correction and angle of attack correction considering the three-dimensional effect are applied for this study. The power coefficient curve shows maximum peak at the rated tip speed ratio of 6.0, and the maximum torque coefficient is developed at the tip speed ratio of 4. The drag coefficient reaches about 0.85 at the design tip speed ratio.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1279-1286
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• 2010

This paper deals with the influence on the dynamic response of I-type girder railway bridge with high-speed electric multiple unit(HEMU) train load. This bridge system which has six I-girder and several cross beams, is modeled with plate and frame elements. And the upper slab is assumed to be fully connected with girders using rigid rinks. Span lengths, types of vehicle and running speeds are selected as parameters for analyses. For more exact analysis, it was adopted that 3-dimensional section of bridge models was produced by the assumed design wheel loads of HEMU vehicle at 200~350 km/hr speeds. Dynamic vertical deflections, dynamic amplification factors and vertical accelerations of bridges having 30 and 35 m span length were investigated and compared with the limit values specified in various national railway bridge specifications.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1293-1299
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• 2010

Daegu urban railroad line 3 is introduced with straddle-type monorail system within the country at the first time. This system is long line with 24km in total length which has not the results of construction in Korea. The rail beam of monorail bridge to be constructed/ installed in the city is adopted on the basis of the PSC rail beam. It is required to apply the steel rail beam at rapid/ curved line parts or location to be required the long span bridge as passing river and intersection. The composition of span bridge is various and the height of bridge is change with each section and exist the different curve radius due to all section is passes in the city. The rail beam shall be considered the ground conditions and then consider the construction methods. It is analyzed to construction period of PSC rail beam to be linked with period of infrastructure construction and construction of steel rail beam, structure construction of station etc. It is compared to crane construction methods and launching girder as alternative construction methods and propose to upper construction methods which is superior in economic and construction.