• Journal of Korean Foot and Ankle Society
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• v.3 no.1
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• pp.26-32
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• 1999

Fractures of the tibial pilon are the severe injuries to the ankle joint resulted from axial compression, shear and/or rotational forces. The pilon fractures have been difficult in management due to the severe comminution of articular surface and frequent soft tissue problem. Among many treatment options, limited internal fixation of the tibia with long screws and multiple pins augmented with external fixation or casting provide adequate stabilization without soft tissue compromise. Among the patients of pilon fracture admitted to our hospital from March 1993 to March 1997 who treated by limited internal fixation and external fixation or casting, 25cases are included who could be follow up for more than 10months. According to Ruedi and Allgower, typeI 3cases, typeII 14cases, typeIII 8cases. The authors analyzed the clinical and radiological results of the tibial pilon fractures according to Magnusson. The results were as follow. 1. 10cases at Ruedi-Allgower typeII were obtained above fair and 5cases at Ruedi-Allgower typeIII were obtained above fair. 2. The postoperative complications were skin problem(3cases) and infection(2cases), which were treated by antibiotics and flap surgery.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.253-265
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• 1993

This paper presents a numerical method for implementing a nonlinear constitutive material model developed by Lade, into a finite element computer program. The techniques used are based on the displacement method for the solution of axial symmetric and plane strain nonlinear boundary value problems. Laboratory behaviour of Baekma river sand(#40-60) is used to illustrate the determination of the parameters and verification of the model. Computer procedure is developed to determine the material parameters for the nonlinear model from the raw laboratory test data. The model is verified by comparing its predictions with observed data used for the determination of the parameters and then with observed data not used for the determination. Three categories of tests are carried out in the back-prediction exercise; (1) A hydrostatic test including loading and unloading response, (2) Conventional triaxial drained compression tests at three different confining pressure and (3) A model strip footing test not including in the evaluation of material parameters. Pertinent observations are discussed based on the comparison of predicted response and experimental data.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.324-333
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• 2012

The conventional medium and large caliber gun, in general, utilize the hydro-pneumatic recoil mechanism to control the firing impulse and to return to the battery position. However, this kind of mechanism may cause the problems like the leakages and the property changes in oil and gas due to the temperature variations between low and high temperatures. Accordingly, the friction spring mechanism has recently been researched as an alternative system. The friction spring mechanism consists of a set of closed inner and outer rings with the concentric tapered contact surfaces assembled in the columnar form, and can only be used under the compression load. When the spring column is axially loaded, the tapered surfaces become overlapped, causing the outer rings to expand while the inner rings are being contracted in diameter allowing an axial displacement. Because of friction between tapered contact surfaces, much higher spring stiffness is obtained on the stroke at the increase in load than the stroke at the decrease. In this paper, the dynamic equations regarding the friction spring system and the design approach have been investigated. It is also tried for a dynamic model representing the recoil motion and the friction spring forces. And the model has been proved from firing test using a gun system with friction springs. All the results show that the recoil mechanism using friction springs can substitute for the classic hydro-pneumatic recoil system.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.3
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• pp.277-289
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• 2011

This study proposes a new testing method for shear bearing capacity of FRP-concrete interface, which could well consider a loading condition corresponding to a tunnel lining undergoing axial compression and could be easily carried out with a simply specified specimen. A parametric study is carried out for capturing an optimized condition of coarse-sand coating of FRP, which governs shear bearing capacity of FRP-concrete interface, by using the proposed testing manner in this study. From the parametric study, it is shown that the proposed testing method is reasonably feasible in comparison with the existing testing methods. An optimum condition of coated sand size and sand density is given for the shearing capacity of FRP-concrete interface.

• Steel and Composite Structures
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• v.26 no.6
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• pp.793-808
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• 2018

In this study, the seismic performance of the connections between L-shaped columns composed of concrete-filled steel tubes (L-CFST columns) and H-beams used in high-rise steel frame structures was investigated. Seven full-scale specimens were tested under quasi-static cyclic loading. The variables studied in the tests included the joint type, the axial compression ratio, the presence of concrete, the width-to-thickness ratio and the internal extension length of the side plates. The hysteretic response, strength degradation, stiffness degradation, ductility, plastic rotation capacity, energy dissipation capacity and the strain distribution were evaluated at different load cycles. The test results indicated that both the corner and exterior joint specimens failed due to local buckling and crack within the beam flange adjacent to the end of the side plates. However, the failure modes of the interior joint specimens primarily included local buckling and crack at the end plates and curved corners of the beam flange. A design method was proposed for the flexural capacity of the end plate connection in the interior joint. Good agreement was observed between the theoretical and test results of both the yield and ultimate flexural capacity of the end plate connection.

• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.231-242
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• 1999

This paper presents a numerical study on the flat plates in deep basements, subjected to out-of-plane floor load and in-plane compressive load due to soil and hydraulic lateral pressure. For nonlinear finite element analysis, a computer program addressing material and geometric nonlinearities is developed. The validity of the numerical model is established by comparison with existing experiments performed on plates simply supported on four edges. The flat plates to be studied are designed according to the Direct Design Method in Korean Building Code for Structural Concrete. Through numerical study on the effects of different load combinations and loading sequence, the load condition that governs the strength of the flat plates is determined. For the plates under the governing load condition, parametric studies are performed to investigate variations of the strength with reinforcement ratio, aspect ratio, concrete strength, and slenderness ratio. Based on the numerical results, the floor load magnification factor is proposed.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.3
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• pp.275-280
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• 2011

In the present study, a unified viscoplastic-damage model has been applied in order to describe the mechanical characteristics of fresh water ice such as nonlinear material behavior and volume fraction. The strain softening phenomenon of fresh water ice under quasi-static compressive loading has been evaluated based on unified viscoplastic model. The material degradation such as growth of slip/fraction has quite close relation with material inside damage. The volume fraction phenomenon of fresh water ice has been identified based on volume fraction (nucleation and growth of damage) model. The viscoplastic-damage model has been transformed to the fully implicit formulation and the discretized formulation has been implemented to ABAQUS user defined subroutine (User MATerial: UMAT) for the benefit of application of commercial finite element program. The proposed computational analysis method has been compared to uni-axial compression test of fresh water ice in order to validate the compatibilities, clarities and usefulness.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.4
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• pp.330-335
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• 2011

This paper presents estimation of average compressive strengths of three types of stiffened panels under lateral pressure and axial compression based on simplified formulas from CSRs and nonlinear FEAs. FEA scenarios are prepared based on the slenderness ratios of the stiffened panels used for in-service vessels. The seven step lateral pressures by 1bar increment are imposed on FE models assuming maximum 30m water height. The number of FEAs for FB-, AB-, and TB-stiffened panels is totally 189 times. FEA results show that existence of pressure can evolves significant reduction of ultimate strengths, meanwhile CSR formulas do not take into account the lateral pressure effect. Lateral pressure acting on the stiffened panel with higher column slenderness ratio more reduces the ultimate strengths than those with smaller column slenderness ratio. A new concept of relative average compressive strain energy instead of the ultimate strength is introduced in order to rationally compare the average compressive strength through complete compressive straining regime. The differences of the ultimate strengths between CSR formulas and FEA results are relatively small for FB- and AB-stiffened panels, but larger discrepancies of relative average compressive strain energies are shown.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.26-34
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• 2016

The failure modes of steel column-base plate connection arranged on the basis of AISC Design Guide-#1 and -#10 are base plate tension and compression side flexural yielding, yielding, pull-out and shear failure of anchor rod, concrete crushing in concrete footing and steel column yielding. The bending moment capacity and failure mode in this connection are predicted using limit-state function and we compare these results and test result. In the case that thickness of base plate is relatively thick, bending moment capacity and failure mode in steel column-base plate connection accurately predicted. But in the case that thickness of base plate is relatively thin and axial force do not exist, prediction of failure mode in this connection is somewhat inaccurate.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.65-74
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• 2002

Composite materials are used for main structural components of aircraft fuselage such as skin, stringer and frame to reduce weight. Failure and buckling analysis of the composite fuselage components have been done for structural design. The loads of MD90-30 are applied to each component. Various shapes of section such as I, Z and T-type are chosen as candidate composite stringer and frame. The analysis results of composite fuselage components are compared according to ply-angle and ply-number, and the section type. The numerical results shows that ply-angle and ply-number have important effects on failure caused by axial load for the frame are important design parameters of composite fuselage components. This study suggests several design tips for composite fuselage components.