• Journal of the Korea Concrete Institute
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• v.18 no.3 s.93
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• pp.379-388
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• 2006

This paper presents a model for evaluating the contribution by arch action to shear resistance in shear-critical reinforced concrete beams. Based on the relationship between shear and bending moment in beams subjected to combined shear and bending, the behavior of a beam is explicitly divided into two base components of the flexural action and the tied arch action. The compatibility condition of the shear deformation that deviates from Bernoulli bending plane is formulated utilizing the smeared truss idealization with an inclined compression chord. The Modified Compression Filed Theory is employed to calculate the shear deformation of the web, and the relative axial displacements of the compression and the tension chord by the shear flow are also calculated. From this shear compatibility condition in a beam, the shear contribution by the arch action is numerically decoupled. Then the validity of the model is examined by applying the model to some selected test beams in literatures. The results may confirm the rationale of the proposed behavioral model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.283-292
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• 2009

Considering an integral equation governing the motion of unfolding fin, an algebraic equation was acquired to get estimated minimum deployment energy required for the successful fin unfolding under the given wind condition. To complete the integration of moment, some approximations had to be introduced particularly to frictional moment and aerodynamic damping for which deployment angular speed of the unfolding fin was modelled as a function of deployment angle only with assumed profile using expected maximum angular speed. Technique for the estimation of the minimum required deployment energy was finalized by introducing the ideal deployment angular speed representing work done by the fin unfolding device alone during fin unfolding and was confirmed by comparing results from simulation with various aerodynamic conditions and profiles of the hinge torque.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.253-260
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• 1998

An approximate method for the calculation of creep deflections of reinforced concrete beams under sustained service loads is proposed. The position of neutral axis and strain and stress distribution of fully cracked section after creep is determined from the requirements of strain compatibility and equilibruim of a section and then the long-term flexural rigidity of fully cracked section is determined based on the new neutral axis. The long-term flexural rigidity of uncracked section at the level of the reinforcenment. The approach of calculating long-term effective flexural rigidity and defections is similar to the current American Concrete Institue procedure for calculating effecitve moment of inertia and short-term deflections. The accuracy of the analysis is verified by comparison with several experimental mesurements of beam deflectons. The result is good between the theotetical values and mesured valus.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.885-888
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• 2009

자동차용 Alloy Wheel은 차량의 수직하중이나 가로 방향 하중, 구동, 제동토크 등 주행 시에 발생하는 여러 형태의 응력을 받으면서 사용되므로 이러한 응력을 견딜 수 있는 강성은 물론 차량 부품으로서의 요구 수명도 만족하여야 한다. 알루미늄 휠은 개발 후 규격에 준하는 내구성 평가를 위하여 반경 방향 부하 내구시험과 굽힘모멘트 내구시험과 주행 중 요철이나 벽돌 등에 의한 노면으로부터 갑작스런 하중에 대한 내충격성 평가를 위한 충격시험이 실행되고 있다. 이러한 시험은 많은 시간이 소요되고 있으며, 또한 시험 중 불합격 판정이 날 경우 또다시 처음의 공정을 모두 거쳐 다시 시험을 하게 된다. 3 Piece와 같은 알루미늄 휠은 여러 공정에 의한 생산되어지기 때문에 많은 시간적, 물질적 손실이 일어나고 있다. 따라서 자동차용 알루미늄 휠의 요구조건을 충분히 만족시키며 소비자의 요구에 맞는 품질과 시간을 충족시켜 기업경쟁력 확보는 물론 원가절감에 의한 기업 경쟁력 향상을 위하여 설계 단계서부터 시험조건을 고려한 내구성 해석에 의한 알루미늄 휠의 시험횟수를 단축하고자 한다. 본 논문에서는 3 Piece 알루미늄 휠의 축(shaft)하중에 의한 내구성 평가에 대하여 CAE시스템을 이용하여 보다 빠르고 정확한 결과를 산출함으로서 설계시간의 단축은 물론 다양한 형상의 제품들을 설계단계에서부터 생산에 이르기까지의 해석활용법을 수립하고자 하였다.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.60-70
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• 1999

The longitudinal stability characteristics of a Wing-In-Ground Effect Craft are quite different from that of the conventional airplane due to the existence of force and moment derivatives with regard to height. This stability characteristics plays a great role in designing a safe and efficient WIG due to its potential danger in sea surface proximity. The static and dynamic stability criteria are derived from the motion equations of WIG in the framework of small disturbance theory and discussed in the paper. The static and dynamic stability analyses of a 20-passenger WIG are conducted based on the wind tunnel test data and the dynamic motion behaviors are investigated for the change of the design parameters. Finally, the flying quality of the 20-passenger WIG is analysed at the cruising condition according to the military regulations.

• Journal of Korean Society of Forest Science
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• v.82 no.1
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• pp.34-43
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• 1993

In this paper, the characteristics of cable logging operations are discussed from a standpoint of mechanics. An example of standing skyline operations is used to illustrate the mechanical principles. Using force and moment boundary conditions, the maximum allowable payload was formulated as a function of slope profile, system geometry and operation options. This formulation includes fundamental equations for log drag and single segment mechanics. The catenary link model is the basic assumption in simulating cable segment stretches. In order to demonstrate the solution procedures of the formulation, a computer model was developed. The model uses Secant algorithm to determine the solution of the complex nonlinear equation set. Finally, the computer model was demonstrated using a hypothetical data set.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.367-374
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• 2012

A dynamic simulation and test of frame with thin walled closed section beams considering warping conditions have been performed. When a beam is subjected under torsional moment, the cross section will deform an warping as well as twist. For some thin-walled sections warping will be large, and accompanying warping restraint will induce axial and shear stresses and reduce the twist of beam which stiffens the beam in torsion. This paper presents that an warping restraint factor in finite element model effects the behavior of beam deformation and dynamic mode shape. The computer modelling of frame is discussed in linear beam element model and linear thin shell element model, also presents a correlation between computer predicted and actual experimental results for static deflection, natural frequencies and mode shapes of frame.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.1-15
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• 1992

A Practical and easily applicable methods for the numerical analysis and the optimum design of continuous and horizontally curved two-way slab systems with twelve possible edge conditions are presented. The proposed method for the numerical structural analysis is based on the use of design moment coefficients which are derived from the elastic theory of thin curved plates. The optimum values are selected from within the feasible region in the design space defined by the limit state requirements. The sequential linear programming is introduced as an analytical method of nonlinear optimization. The optimum design variables, including a effective depth and transformed steel ratios per unit width of middle and column strips of slabs, are then determined.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.191-196
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• 2015

해상 pedestal 크레인은 각종 운송물을 선박에 싣거나 내리는 해상 운송에 필수적인 장비이다. 따라서 구조적 안전성을 가지는 크레인 설계가 요구된다. 그의 일환으로 수행된 '해상 pedestal 크레인의 설계 개선을 위한 연구'에서는 기존 크레인의 기초 설계에 대해서 구조적 안전성올 평가하여 개선 방안을 제시하였다. 또한 좌굴 안정성 향상을 위한 보강재 설계를 수행하였다. 하지만 상세설계 관점에서 미비한 점이 있어 이를 보완할 필요성이 있다. 안전성 평가를 위해 필요한 응력을 계산하기 위해 EDISON-CSD프로그램을 통해 유한요소모델 해석을 활용한 구조해석을 수행하였다. 효율적인 해석을 위해 상세설계에 필요한 부분영역을 선택하여 모델링 하였으며 전체영역에서의 해석 결과 값을 등가 힘, 등가 모멘트로 환산하여 경계조건으로 부여하였다. 보강재간의 교차점 형상이 안전성에 미치는 영향을 보기위해 stiffener와 diaphragm의 교차점 형상(반원, 정사각형, 사다리꼴)에 따라 안전성 평가를 수행하였고, 안전 여유의 유효한 차이를 보이지 않음을 확인하였다. 평가에 필요한 응력계산을 위해 또한 Diaphragm의 좌굴에 대한 영향을 고려하기 위해 설계 규격 DNV-RP-201 8장(Buckling of girders)을 분석하였고, 안전성 평가에 반영하였다. 또한 실제 현장에서 보편적으로 사용되는 angle 형상 stiffener의 치수 도출을 위해 최적설계를 수행하였고, 모든 설계 제한조건을 만족하면서 최소의 무게를 가지는 합리적인 치수를 도출하였다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.103-106
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• 2011

국토해양부령 제320호인 건축물의 피난 방화구조 등의 기준에 관한 규칙 제 3조에서는 내화구조에 관한 세부기준을 정하고 있다. 이러한 법정내화구조 중에서 철골철망 모르타르조의 피복두께에 따른 내화성능 변화를 분석하기 위하여, 본 연구에서는 고온 재하하중조건에서 내화실험을 수행하였다. 철골조의 피복두께를 50 mm ${\cdot}$ 60 mm ${\cdot}$ 70 mm로 변화하여 내화실험을 수행하였으며, 재하하중비를 변화시킴으로 동일 피복두께에서의 내화성능 변화를 분석하고자 하였다. 실험결과 단면소성모멘트 대비 하중비 0.4 조건에서의 철골철망 모르타르조의 내화성능은 180분이 나왔으며, 피난 방화구조 등의 기준의 별표 1에서 정하고 있는 내화구조의 성능기준 중 최대 내화성능시간인 3시간을 확보하는 것으로 나타났다.