• Proceedings of the KSR Conference
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• 2002.10a
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• pp.690-695
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• 2002

Two plate girders bridge has an advantage for execution of works and quality control because of its simplicity of super-structure caused by decreasing in amount of members and also is distinguished as aesthetic bridge type. Recently this has been adopted for structure of highway as well railway and introduced into domestic. In order to plan or design two plate girders bridge more rationably, it is necessary to comprehend its structural behavior as well as to consider the critical resign factors. Thus, in this study the formulation of optimum design for two plate girders bridge is proposed and the critical resign variables ani restraints are considered and founded by caring out optimum design. The objective function of optimization is formulated as a minimum cost design problem. And the thickness and length of I-shaped section are decided as resign variables. The design constraints are formulated based on Design Criteria for Railroad(Bridges). By comparing the optimum results with those of the conventional resign, the effectiveness of proposed optimum design formulation is investigated. From the results, the way to do optimum design of two plate girders bridge is suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.493-496
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• 2004

The change of creep deformation mechanism due to the persistent change of stress conditions requires the constitutive relation for the analysis of long tenn behaviors considering age dependent material properties of concrete. In the present research, the process of time dependent behaviors in structure is divided into two stages; the non-mechanical deforming level which causes creep and shrinkage deformations, and the mechanical deforming level which causes mechanical deformations by the restraints of non-mechanical deformations due to internal or external factors. The incremental constitutive relation is derived by expanding the total stress-strain relation on the present time, with respect to the reference time using the Taylor series, and the modulus of elasticity in early ages of concrete was defined thru this process.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.86-93
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• 2003

These days, automobile industry pays considerable attention to child occupant safety. As the US adopted requirements for universal and uniform anchor systems for child restraints, manufacturers for child seats put an enormous effort to improve the protective properties of Child Restraint System (CRS). Various standards have been studied and announced by different countries. The anchorage system is the most important in the CRS and the rules of universal anchor are to provide devices which are independent of safety belts. A new concept called International Standard Organization Fixture (ISOFIX) has been announced. It suggests some designs for the CRS. In this study, the suggested designs are evaluated with domestic products. Tests are performed and the results are incorporated into a finite element modeling process. As the finite element model is established, various numerical tests are conducted and the numerical results are discussed. A commercial software system is utilized for the nonlinear finite element analysis.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.218-219
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• 2007

Silicon feed stock shortage have acted as major restraints for growth of photovoltaic industry. Concentrating photovoltaic (CPV) system will reduce the use of silicon PV materials. This paper presents the application possibility of mono-crystalline silicon solar cell, which has increased in market share, for PV concentrator. We measured the power of solar cell using sun simulator and I-V curve tracer and compared the results. The comparison of results showed that the concentrated solar cell generated the power more approximately 7 times than without concentration in spite of non-heat sink. If CPV technology included heat sink combines already developed PV tracking system, it will have a merit economically.

• Journal of the military operations research society of Korea
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• v.18 no.1
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• pp.15-31
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• 1992

Developments toward a 'the end of the Cold War' are the main factor determining the situation in the Korean Peninsula. While all the combat resources of North Korea are systematically controlled and kept available for instant mobilization even in peacetime. South Korea is inferior to North Korea in terms of mobilization system and efficiency, exercise intensity and equipments. In sum, the South faces far greater restraints in wartime conversion capability than does the North. Mobilization refers to a nation's compulsory control, management and operation of its human and material resources for the purpose of national security. The total capability for safeguarding national security must be pursued by the continuous examination and complementation of our mobilization system and capability. This paper proposes an efficient management of national mobilization system that can be instantly operated on the whole in time of national emergency. Therefore, the actual operation of National Security Council is suggested to prepare operations against the emergencies and establish the foundation for national security.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.604-607
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• 2005

The free vibration of solid circular plates has been studied using the differential transformation method(DTM). The effects such as mass at edge and elastic restraints have been considered. In order to avoid the singularity problem at the solid circular center two regularity conditions were applied with respect to the number of circumferential nodal line. The non-dimensional natural frequencies of the general circular plates were obtained for various boundary conditions. The results obtained by this method were compared with previous works. DTM showed fast convergency, accuracy, efficiency and validity in solving vibration problem of general circular plates.

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.13-19
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• 2008

A camprehensive review of the expansion behavior of marine pipelines due to thermal and pressure change is presented based on research work over the last 10 years. The review is organized into five main sections, namely free expansion with uniform temperature, free expansion with temperature gradient, expansion with end restraints, expansion of pipe-in-pipe system, and lateral deviation (snaking). Based on the accumulated knowledge of the interactions between the soil and pipeline behavior, a whole pipeline system can be modeled by an accurate finite element method (FEM). This methodology requires a comprehensive understanding and engineering verification of the expansion behavior of marine pipelines.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.649-653
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• 1995

Solution-state structure of native F430 was determined by using NMR methods and NMR-based distance geometry (DG) computations. Structures were generated with loose NOE-derived interproton distance restraints (2.0-2.5 Å, 2.0-3.5 Å and 2.0-4.5 Å for strong, medium, and weak NOE cross-peak intensities, respectively). 2D NOESY back-calculations of structures were subsequently carried out for establishing the consistence between experimental data and DG-model structures. The back-calculated 2D NOESY spectra of resulting DG structures were well consistent with experimental 2D NOESY spectra. Superposition of 20 independent structures with macrocyclic ring atoms and all atoms of F430 afforded pairwise root mean square deviations (RMSD) of 0.025-0.125 Å and 0.64-1.3 Å, respectively. The macrocyclic rings of structures are well converged to a unique conformation with saddle-shaped deformation whereas most of side chains are not converged. The average dihedral angle (N1-N2-N3-N4, 27.78±1.50°) of 20 DG-structures exhibits that the macrocyclic ring conformation is puckered as much as 12,13-diepimeric F430 (28.75±4.07°).

• Advances in aircraft and spacecraft science
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• v.3 no.1
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• pp.45-59
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• 2016

In this paper, the condensation method which is based on the Rayleigh-Ritz method, is described for the free vibration analysis of axially loaded slightly curved beams subject to partial axial restraints. If the longitudinal inertia is neglected, some of the Rayleigh-Ritz minimization equations are independent of the frequency. These equations can be used to formulate a relationship between the weighting coefficients associated with the lateral and longitudinal displacements, which leads to "connection coefficient matrix". Once this matrix is formed, it is then substituted into the remaining Rayleigh-Ritz equations to obtain an eigenvalue equation with a reduced matrix size. This method has been applied to simply supported and partially clamped beams with three different shapes of imperfection. The results indicate that for small imperfections resembling the fundamental vibration mode, the sum of the square of the fundamental natural and a non-dimensional axial load ratio normalized with respect to the fundamental critical load is approximately proportional to the square of the central displacement.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1065-1068
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• 2008

Concrete is still one most common construction materials even in railway structures. As structures become massive and mega-sized, the importance of early age concrete quality control becomes more significant. Among various factors, relative humidity and temperature are the primary factors governing the early age quality. Temperature raise due to cement hydration causes stress, which can develop to cracking with internal and/or external restraints. Exposure conditions including ambient temperature, humidity and wind also significantly affect the cracking behavior of early age concrete. Among many of studies on the early age concrete behavior, investigation on the variation of temperature and relative humidity internal of concrete is not common. That is in part because the difficulties in measuring the relative humidity and temperature inside the concrete. This study used a digital sensor with an appropriate logger to measure internal temperature and relative humidity. This direct measuring method is expected to provide more reliable and comprehensive data acquisition on the early age behavior of concrete.