• Structural Engineering and Mechanics
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• v.28 no.5
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• pp.587-601
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• 2008

In this study, a numerical procedure based on the finite element method for materially and geometrically nonlinear analysis of reinforced and prestressed concrete slender columns with arbitrary section subjected to combined biaxial bending and axial load is developed. In order to overcome the low computer efficiency of the conventional section integration method in which the reinforced concrete section is divided into a large number of small areas, an efficient section integration method is used to determine the section tangent stiffness. In this method, the arbitrary shaped cross section is divided into several concrete trapezoids according to boundary vertices, and the contribution of each trapezoid to section stiffness is determined by integrating directly the trapezoid. The space frame flexural theory is utilized to derive the element tangent stiffness matrix. The nonlinear full-range member response is traced by an updated normal plane arc-length solution method. The analytical results agree well with the experimental ones.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.421-426
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• 2005

Scattering center extraction schemes for radar cross section reduction of large complex targets, like warships, was developed, which are an 1-D radar image method(range profile), and a direct analysis based on an object precision method. The analysis result of partial dihedral model shows that the presented direct analysis method is more efficient than the 1-D radar image method for scattering center extraction of interested targets, in terms of radar cross section reduction design, not signal processing. In order to verify the accuracy of the direct analysis method, a scattering center analysis of an naval weapon system was carried out, and the result was coincident with that of another well-known RCS analysis program. Finally, an analysis result of RCS and its scattering center of an 120m class warship-like model presented that the direct analysis method can be an efficient and powerful tools for radar cross section reduction of large complex targets.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.337-340
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• 2008

The cross section shape of intermediate die is one of important parameters to obtain dimensional accuracy of final product in shaped drawing process. Until now it has been designed by the experience or trial and error of the expert. In this study, the cross section shape of intermediate die fur spline shape is determined by the electronic field analysis, shape factor method. The result of the electronic field analysis, shape factor method has been compared with that of the present method. The effects of cross section shape on the dimensional accuracy were investigated by using FE analysis. And then the multi-stage shaped drawing experiments were performed to verify the results of FE analysis. As a result, the cross section shape from the electronic field analysis had the good dimensional accuracy. The electronic field analysis can be used for the method to obtain the cross section shape of intermediate die in shaped drawing process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1661-1666
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• 2003

The purpose of this study is to develop the simplified model of the crankshaft in the large marine engine for dynamic analysis. Because the actual engine system is under complex dynamic loading condition and it has multi-cylinder, the dynamic analysis is purchased at a high computation cost. In spite of this burden, the dynamic analysis must be perfonned to assure structural integrity of operating marine engine. Therefore, simplification of the analytic model is necessary for dynamic analysis. Beam-mass model, which is generated with the section property method, is the model simplified effectively. Section property method can provide desired section information by optimization technique. By applying beam-mass model to the crankshaft in the large marine engine, the usefulness of the proposed method was proven.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.143-151
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• 2008

In this paper, the optimum design of plane steel frames using second-order inelastic analysis and section increment method is presented. Since the second-order inelastic analysis accounts for geometric and material nonlinearities of the whole system as well as its component members, the design method based on second-order inelastic analysis does not require separate member capacity checks after analysis. A section increment method proposed by this paper is used as optimization technique. The weight of structures is treated as the objective function. The constraint functions are defined by load-carrying capacities, deflections, inter-story drifts, and ductility requirement. The effectiveness of the proposed method are verified by comparing the results of the proposed method with those of other method.

• Journal of Information Technology Services
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• v.13 no.2
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• pp.251-259
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• 2014

Outdoor cultural properties have been damaged by natural weathering and air pollution for a long time. For this reason, there are many characteristics it is hard to decipher some carved inscription on the surface of damaged outdoor cultural properties. Until now, Rubbed copy has been widely used to decode engraved inscription. A investigation for epigraph has been made by the rubbing that has resulted in a lower resolution from the viewpoints of extraction process and used materials. Rubbing's results are not satisfied in the damaged inscriptions which are weathered by natural environment and pollution for a long time and in the narrowed one. The main analysis presented in this paper is a cross section analysis method using 3d scanning technique for epigraph not read. Cross section analysis is a study on readability improvement method for ancient inscription of irregularity monument surface. Cross section analysis confirms information that separated the inscription information of monument and the ground information to read a ancient inscription and decode the inscription information. The proposed character identification method contributed to decoding an ancient inscription on Silla Monument in Jungseong-ri of Pohang.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.16-24
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• 2007

The high-frequency analysis method of back-scattering cross section spectrum of rotating targets is established. The time history of the back-scattering cross section is calculated using a quasi-stationary approach, based on a physical optics and a physical theory of diffraction, combining an adaptive triangular beam method to consider the shadow effect. And the spectra of back-scattering cross section by the Doppler effect are analyzed applying a simple fast Fourier transform method to its time history. The numerical calculation for rotating targets, such as rotating metal plates and underwater propeller, are carried out. The time history appears to be periodic with respect to the number of wings. The backscattering cross section spectrum level and its frequency shift are dependent on the rotating speed, direction, and the shape of the targets.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.401-413
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• 2022

This paper provides a simple method by which to estimate the cross-section stress profiles for nozzles designed according to ASME Code Section III. Further, this method validates the effectiveness of earlier work performed by the authors on standard nozzles. The method requires only the geometric information of the pressure vessel and the attached nozzle. A PWR direct vessel injection nozzle, a PWR outlet nozzle, a PWR inlet nozzle and a BWR recirculation outlet nozzle are selected based on their corresponding specific designs, e.g., a varying nozzle radius, a varying nozzle thickness and an outlet nozzle boss. A cross-section stress profile comparison shows that the estimates are in good agreement with the finite element analysis results. Differences in stress intensity factors calculated in accordance with ASME BPVC Section XI Appendix G are discussed. In addition, a change in the dimensions of an alternate nozzle design relative to the standard values is discussed, focusing on the stress concentration factors of the nozzle inside corner.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.695-702
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• 2008

In this paper, a new numerical method is proposed to analyze near-field sonar cross section of acoustically large-sized underwater targets such as submarines. A near-field problem is converted to a far-field problem using a spherical projection method with respect to the objective target. Then, sonar cross section is calculated with a physical optics well established in far-field acoustic wave scattering problems. The analysis results of a square flat plate compared with those obtained by other method show the accuracy of the proposed method. Moreover, it is noted that the sonar cross section is varied with respect to the targeting point as well as the range. Finally, numerical analysis results of real-like underwater target such as a submarine pressure hull are discussed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.764-771
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• 2006

The use of 3-D finite elements for the eigen analysis of beam-like structures with arbitrary section shape may not be practical in certain cases, from the aspect of CPU time. In this connection, this paper presents a systematic algorithm for decomposing an arbitrary section into finite number of basic ones and computing essential sectional quantities required for the eigen analysis using the beam theory. The numerical accuracy of the proposed method is assesed from the comparison with the 3-D finite . element method.