• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.469-477
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• 2006

Models to predict the ultimate strength of simply supported or continuous deep beams with web openings are proposed. The derived equations are based on upper-bound theorem. The concrete is assumed as a perfectly plastic material obeying the modified Coulomb failure criteria with zero tension cutoff. Reinforcing bar is considered as elastic-perfectly plastic material and its stress is calculated from the limiting principal compressive strain of concrete. The governing failure mechanisms based on test results are idealized as rigid moving blocks separated by a hyperbolic yield line. The effective compressive strength of concrete is calculated from the formula proposed by Vecchio and Collins. Comparisons with existing test results are performed, and they show good agreement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.513-523
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• 2016

The stress concentration factors and stress intensity factors for a simple beam and a cantilever are analyzed by using finite element method and phtoelasticity. Using the analyzed results, the estimated graphs on stress concentration factors and stress intensity factors are obtained. To analyze stress concentration factors of notch, the dimensionless notch length H(height of specimen)/h=1.1~2 and dimensionless gap space r(radius at the notch tip)/h=0.1~0.5 are used. where h=H-c and c is the notch length. As the notch gap length increases and the gap decreases, the stress concentration factors increase. Stress concentration factors of a simple beam are greater than those of a cantilever beam. However, actually, the maximum stress values under a load, a notch length and a gap occur more greatly in the cantilever beam than in the simple beam. To analyze stress intensity factors, the normalized crack length a(crack length)/H=0.2~0.5 is used. As the length of the crack increases, the normalized stress intensity factors increase. The stress intensity factors under a constant load and a crack length occur more greatly in the cantilever beam than in the simple beam.

• Magazine of the Korea Concrete Institute
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• v.8 no.3
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• pp.177-185
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• 1996

Four types of experiments were performed to check the similitude of member behavior between prototype and 1 /10 scale models : (1) Test of slender columns with P-$\Delta$ effect, (2) Test of short columns with and without confinement steel, (3) Test of simple beams without stirrups, and (4) 'T-beam test. Based on the results of experiments, the conclusions were made as follows : (1) The P-$\Delta$ effect of slender columns can be almost exactly represented by 1/10 scale model. (2) The effect of confinement on short columns by the hoop steel can be also roughly simulated by 1/10 scale model. (3) The failure modes of simple beams without stirrups are brittle shear failures in prototype whereas those of 1/10 scale models are the ductile yielding of tension steel followed by large diagonal tension cracking and compressive concrete failure. (4) The behaviors of prototype and 1/10 scale model in T-beams appear very similar.

• Journal of KIISE:Software and Applications
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• v.28 no.1
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• pp.31-45
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• 2001

퍼지 시스템의 설계시, 퍼지 시스템의 성능 저하 없이 최적의 퍼지 규칙 선택과 퍼지 소속 함수의 단순한 정의는 매우 중요하다. 이러한 목적을 이루기 위해서, 본 논문에서는 입력 공간에 강한 영향을 보이는 퍼지 규칙만을 퍼지 규칙으로 선택함으로써 입력 공간의 증가에 유연하게 대처할 수 있는 퍼지 규칙 구조를 제안한다. 또한, 유전자 알고리즘의 진화 탐색을 통하여 퍼지 시스템의 최적화된 구조를 얻기 위해서 퍼지 시스템의 구조를 생성시키는 문법 규칙을 해개체로 코딩하는 문법 코딩을 이용한 유전적 퍼지 시스템을 제안한다. 문법 규칙은 퍼지 규칙의 복잡한 구조를 단순한 모듈 구조로 표현하므로 문법 규칙의 코딩은 유전자 알고리즘의 빠른 수렴과 효율적인 탐색을 보장한다. 아울러, 제안하는 방법을 많은 입력 공간을 갖는 아이리스 데이타(Iris data) 문제와 시간열 예측(time series prediction) 문제에 적용함으로써 제안하는 방법의 응용성을 보이고 성능을 분석한다. 실험 결과, 제안하는 방법이 직접 코딩을 사용한 다른 설계 방법보다 더 좋은 성능을 보여 주었다.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.165-173
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• 2008

In order to promote the practicality of high-rise steel buildings, the development of structural system which have the better fire resistance, the changeable plan, and the quality control of construction with general composite beams is needed. In this research, new semi-slim floor which the defect of general slim floor was complemented was evaluated to investigate the concrete integration with slim-flor beam and the flexural performance. 5 simply supported semi-slim floor beam tests were performed with parameters; structural form of slab support beam, slab thickness, with or without web opening, and shear connection. Experimental results showed that all specimen s had good ductile behavior.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.567-574
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• 2010

As a eco-friendly material, Hwangtoh(red clay) has been studied for a partial or complete replacement of portland cement. Most of existing studies focused on the mechanical properties of the Hwangtoh concrete including the compressive strength, drying shrinkage, creep. In the present study, the flexural capacity of the beams made with the Hwangtoh concrete was tested. One of the concrete tested consisted of activated Hwangtoh replacing 20% of the cement. The other consisted 100% activated Hwangtoh replacing all the cement. The simple beams were tested under two point static loading. The flexural strength, cracking moment, deflection, and ductility were compared with those of the beams made with ordinary portland cement concrete.

• Journal of Korean Society of Steel Construction
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• v.16 no.2 s.69
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• pp.225-233
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• 2004

Composite action is generally achieved by providing shear connections between steel top flange and concrete topping. Composite sections have greater stiffness than the summation of the individual stiffness of slab and beam. Therefore, they can carry larger loads or similar loads with appreciably smaller deflection and are less prone to transient vibration. T-type Steel Composite beam (TSC-beam) was developed to increase these advantages. Ten specimens were tested for this study. During the experiment, crack pattern and deflection of beam were investigated. The examined results of TSC beam system were compared with results from the typical composite beam and RC beam.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.100-107
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• 2010

This study evaluates the bond behavior of reinforced concrete (RC) beams using recycled coarse aggregates. A total of four specimens were cast and tested. The test parameter was the type of coarse aggregates, that is, natural and recycled coarse aggregates, and the absorption ratio of recycled coarse aggregate. The recycled coarse aggregates with absorption ratios of 3% and 6% were used in this test. The specimens were simply supported and were subjected to a concentrated load. A test method proposed by Ichinose was adopted to estimate effectively the bond properties of specimens. From the experimental results, it was found that there was no difference of bond characteristics according to the absorption ratio of recycled coarse aggregates.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.177.1-182
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• 2002

본 연구는 합성교량의 경우 브라켓이나 가로보에 사용되고 비합성교량의 경우 연결재로 사용되는 스랩앵커를 Push-Out Test를 하여 실험으로 얻은 특성을 실제 소수주형모델에 적용하여 FEM해석을 통하여 거동특성을 파악 하고자 한다. 일반적으로 전단연결재 실험의 경우 콘크리트 슬래브와 강재 주형 사이에 직접 길이 방향 전단력을 작용시킬 수 있을 뿐 아니라 실험의 편리함 때문에 주로 Push-out 실험이 많이 이용되고 있다. 본 실험에서는 BS-5400에 제시된 바에 근거하여 실험체를 제작하였다. 이 실험을 통하여 탄성구간에서의 강성(k) 값을 알아내어 3D FEM 해석에 적용한다. 이때 콘크리트 바닥판과 강재와의 연결을 축 방향으로는 특정한 강성 값을 넣을 수 있는 Joint Element를 사용하여 연결시키고, 1경간 단순지지와 2경간 연속교에 대하여 연구를 수행하는데, 1경간 단순지지의 경우에는 Joint Element에 여러 강성 값과 실험을 통해 얻은 강성 값을 적용하여 합성거동을 파악하고 강성 값에 따른 합성정도를 규명하고자 한다. 또한 2경간 연속교에서는 슬랩앵커의 강성 값을 적용하여 많이 문제시되고 있는 내부지점부에 슬랩앵커를 사용하였을 때 슬래브의 인장응력이 어떤 변화양상을 나타내는지 파악 하고자한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.499-501
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• 2002

본 논문은 푸리에영역에서 상관을 계산하기 위한 합성화상을 이용하여 에러가 포함된 화상의 패턴매칭 및 검증에 유효한 새로운 패턴매칭 알고리즘을 제안한다. 두개의 화상을 푸리에변환하여 합성화상을 계산하면 원화상의 중요한 성질은 푸리에영역에서 만들어진 합성화상의 중심부분에 집중된다는 데 착안하여 푸리에공간에 나타난 화상의 중심부분만을 추출하여 비교함으로써 화상의 동일여부에 관한 검증이 보다 단순하게 이루어질 수 있음을 보인다. 또한 원화상에 잡음이 포함된 경우에 푸리에변환의 공간에서 잡음이 중심 부분에서 먼 곳에 분포되는 것에 착안하여 잡음이 포함된 화상과 원화상의 매칭에도 유효함을 보인다. 실험을 통하여 10개의 표준화상과 가우시안잡음이 첨가된 화상을 사용하여 화상을 구분해 내고, 잡음이 있는 화상은 동일한 화상으로 인식함을 보인다. 실험결과는 합성화상의 중심부분에 존재하는 전체의 0.5%의 화소만을 비교함으로써 패턴인식이 가능함을 보여준다.