• Tunnel and Underground Space
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• v.27 no.4
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• pp.195-204
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• 2017

This case study introduces the construction of large cross section tunnel for underground ventilation system in Sillim-Bongcheon Tunnel Project. In order to grant the safety and efficiency in connecting the ventilation shaft (7.8 m of width, and 6.6 m of height) to a tunnel for axial fan facility (20.8 m of width, and 12.3 m of height), gradual enlargement of tunnel cross section was employed between those and temporary support method was determined based on Q system. In addition, some original designs were revised during construction stage to improve the efficiency of excavation in large cross section tunnel. The advance length was optimized and top heading of the tunnel was excavated without partition in accordance with ground condition and numerical stability analysis results. It is believed that some experiences and considerations in this case study will be useful for the future design and construction in similar large cross section tunnel such as large underground ventilation system or road tunnel with four lanes.

• Journal of the Korean Society for Railway
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• v.9 no.1 s.32
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• pp.102-109
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• 2006

The PSC girders which currently used at highway bridge have the standard cross sections about 25m, 30m and 35m span. Thus, in case of highway bridge design, the bridge designer can choose the adequate standard cross section according to constructional condition. However, in railway bridge design, there are limitations on reasonable bridge design considering circumstances of a construction site and conditions of location etc, because the PSC girders used at railway bridge have the cross section about only 25m span length. In this study, the optimum design for the PSC girder railway bridge with 30m span length has been performed. Also, in order to investigate the dynamic stability of railway bridge using the optimum section of PSC girder, dynamic analysis has been carried out. From the results of analysis, it is suggested to denote the optimum section which satisfied the structural safety, dynamic stability and economical efficiency all together.

• Journal of the Korean Geotechnical Society
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• v.36 no.1
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• pp.29-38
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• 2020

These days the circular cross section cofferdam has been frequently used for the earth retaining structures or cut off wall such as ventilating opening, intake tower in cofferdam, shaft for emergency. By the arching effect, the circular cross section type cofferdam has more advantage than a polygon cofferdam in terms of the structural forces and moment. This paper shows the proper approach to analyze the circular cross section cofferdam using 2D Finite Element Method (FEM) for the circular stiffener (ring beam) evaluation. Besides, the various shapes of cofferdam indluding circular cross section have modeled the 3D Finite Element Mothod (FEM). The circular cross section cofferdam shows the minimum reaction force compared with the other shapes of cofferdam.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.715-723
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• 2012

The Hoelyongpo in the Naeseong River as tributary basin of the Nakdong River is broadly well-known a tourist attraction, which is made of sandy beach, and is called "Island of Inland". But Construction of the Dam was planned at upstream of river. In other words, an influx of sediment is blocked from upstream of river. In this situation, through sediment discharge coming from tributary of the Naeseong river, the whether to go ahead of sand beach of the Hoelyongpo is analyzed by using 1-D and 2-D model. The sediment discharge is estimated through ratio raw with basin area, and the instream flow requirement of river coming from dam and the flow rate and sediment coming from tributary are inputted for model. The 1-D model uses HEC-6 and the 2-D model uses SMS(RMA2 and SED2D). The analysis using the HEC-6 is performed from cross section data 10 year ago to the present cross section. Consequently, Yang equation presenting similar result to the present cross section data is determined, using this, the prediction is conducted for the cross section after 20 years. The 2-D analysis is conducted for the present cross section data. The value of distinction between a deposition and erosion with the results presented in the 1, 2-D models is occur, however, the appearance between the deposition and the erosion is similar.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.5
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• pp.442-449
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• 2009

A two-dimensional cross-section analysis program based on the finite element method has been developed for composite blades with solid, thin-walled and compound cross-sections. The weighted-modulus method is introduced to determine the laminated composite material properties. The shear center and the torsion constant for any given section are calculated according to the Trefftz' definition and the St. Venant torsion theory, respectively. The singular value problem of cross-section stiffness properties faced during the section analysis has been solved by performing an eigenvalue analysis to remove the rigid body mode. Numerical results showing the accuracy of the program obtained for stiffness, offset and inertia properties are compared in this analysis. The current analysis results are validated with those obtained by commercial software and published data available in the literature and a good correlation has generally been achieved through a series of validation study.

• Structural Engineering and Mechanics
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• v.67 no.5
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• pp.465-479
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• 2018

In a previous study, design charts where proposed to help the torsional design of axially restricted reinforced concrete (RC) beams with squared cross section. In this article, new design charts are proposed to cover RC beams with rectangular cross section. The influence of the height to width ratio of the cross section on the behavior of RC beams under torsion is firstly shown by using theoretical and experimental results. Next, the effective torsional strength of a reference RC beam is computed for several values and combinations of the study variables, namely: height to width ratio of the cross section, concrete compressive strength, torsional reinforcement ratio and level of the axial restraint. To compute the torsional strength, the modified Variable Angle Truss Model for axially restricted RC beams is used. Then, an extensive parametric analysis based on multivariable and nonlinear correlation analysis is performed to obtain nonlinear regression equations which allow to build the new design charts. These charts allow to correct the torsional strength in order to consider the favourable influence of the compressive axial stress that arises from the axial restraint.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.21-28
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• 2024

In this paper, two prediction models based on deep neural network that could predict cross-sectional stiffness of a rotor blade were proposed. Herein, we employed structural and material information of cross-section. In the case of a prediction model that used material properties as the input of the network, it was designed to predict the cross-sectional stiffness by considering elastic modulus of each cross-sectional member. In the case of the prediction model that used structural information as a network input, it was designed to predict the cross-sectional stiffness by considering the location and thickness of cross-sectional members as network input. Both prediction models based on a deep neural network were realized using data obtained by cross-sectional analysis with KSAC2D (Konkuk section analysis code - two-dimensional).

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.165-175
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• 2000

In order to improve the function of a door seal, its section design technique is discussed in this study, Its roles are prevention of an inflow of dusts, noise interception, insulation, wateproof, and the vibroisolating action which reduces vibration between the body and the door of a car while running, and the buffer action which sustain the proper reacting force as the door is closed. In this study, the optimal cross section of a door seal is designed using nonlinear finite element analysis (commercial finete element analysis program EASi-SEAL) and tables of orthogonal arralys with respect to relations between door and door seal to secure the satisfactory airtight property with the minimum force to shut the door.

• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.2016-2024
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• 2005

In this work, a mixed beam approach that combines both the stiffness and the flexibility methods has been performed to analyze the coupled composite blades with closed, two-cell cross-sections. The Reissner's semi-complementary energy functional is used to derive the beam force-displacement relations. Only the membrane part of the shell wall is taken into account to make the analysis simple and also to deliver a clear picture of the mixed method. All the cross section stiffness coefficients as well as the distribution of shear across the section are evaluated in a closed-form through the beam formulation. The theory is validated against experimental test data, detailed finite element analysis results, and other analytical results for coupled composite blades with a two-cell airfoil section. Despite the simple kinematic model adopted in the theory, an accuracy comparable to that of two-dimensional finite element analysis has been obtained for cases considered in this study.

• Structural Engineering and Mechanics
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• v.43 no.1
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• pp.15-30
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• 2012

A damped Timoshenko beam element is introduced for the DOF-efficient forced vibration analysis of beam-like structures coated with viscoelastic damping layers. The rotary inertia as well as the shear deformation is considered, and the damping effect of viscoelastic layers is modeled as an imaginary loss factor in the complex shear modulus. A complex composite cross-section of structures is replaced with a homogeneous one by means of the transformed section approach in order to construct an equivalent single-layer finite element model capable of employing the standard $C^{0}$-continuity basis functions. The numerical reliability and the DOF-efficiency are explored through the comparative numerical experiments.