• 한국강구조학회 논문집
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• 제10권1호통권34호
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• pp.25-35
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• 1998

각형 강관 기둥과 H형 보의 접합부에 대한 연구는 보의 하중을 기둥에 전달하는 과정에서 생기는 응력의 집중현상 때문에 하중을 효율적으로 전달하는 방식을 고안하는 것에 초점을 맞추었다. 본 연구에서는 외부보강형 접합부의 강도를 증가시키기 위한 방법으로 직사각형의 스티프너를 사용하였다. 실물의 절반크기로 시험체를 제작하여 단순 인장실험을 실시하였다. 항복선이론과 가상일법을 이용하여 접합부의 극한강도를 추정하는 공식을 유도하였으며 실험치에 근접한 결과를 얻었다.

• 대한수학회지
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• 제49권5호
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• pp.977-991
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• 2012

Let (M,F) and (M',F') be two foliated Riemannian manifolds with M compact. If the transversal Ricci curvature of F is nonnegative and the transversal sectional curvature of F' is nonpositive, then any transversally harmonic map ${\phi}:(M,F){\rightarrow}(M^{\prime},F^{\prime})$ is transversally totally geodesic. In addition, if the transversal Ricci curvature is positive at some point, then ${\phi}$ is transversally constant.

• 수산해양기술연구
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• 제41권3호
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• pp.199-206
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• 2005

As the basic study about improvement of yellow croaker drift gill net fishing implement and development of the fishing system, this study drew problem after synthetically analyzing hauling system of yellow croaker drift gill net used in the coast of Chuja Island and tested several characters and analyzed in hauling process with 5 step net hauler model for improving the problem. The analysis results are as follows. When the angle between axises of drum centers was small, it showed the tendency that hauling time was fast. Hauling time was faster when drum was 5 step rather than 3 step. When drum was 5 step, slippery phenomenon was small and hauling was stable. Tension was larger when drum was 5 step rather than 3 step. When drum was 5 step, the range of change of the maximum and minimum value was small and hauling was stable. When drum was 3 step, there was following formula between hauling time ($Ht_3$) and angle between axises of drum centers ($A_g$) $Ht_3$ : ($7.15Hs^{-0.81}$) $A_g^{-0.81}$, when drum was 5 step there was following formula.$Ht_5$ : ($6.45Hs^{-0.75}$) $A_g0.10$, here, Hs is hauling speed. When drum was 3 step and hauling speed was 28cm/sec, tension was $T=0.08A_8^3-1.60A_g^3-0.49A_g+369.56(r=0.99)$, when drum was 5 step, tension was, $T=-0.01A_g^3+1.96A_g^2-34.05A_g+414.58$ (r-0.99), here, T was tension(g).

• 한국철도학회논문집
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• 제15권5호
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• pp.447-453
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• 2012

본 논문은 경부 고속선과 같이 사전이도가 주어지는 기설 전차선로에서 전차선 장력만을 증가시켜 임시적인 속도 향상 도모하는 경우에 팬터그래프와 습동하는 전차선의 접촉 평면상의 기하학적 형상의 변화가 어떻게 될 것인가를 검토한 것이다. 검토를 위하여 우선 사전이도가 있는 경우에도 정확히 드로퍼 길이를 계산해 낼 수 있는 드로퍼 길이 계산 수식에 대하여 알아보았다. 다음으로 드로퍼 길이 계산 수식을 프로그램화한 전용계산 프로그램을 이용하여 경부고속선 전차선로의 49.5m 경간을 대상으로 전차선 장력을 20kN에서 23kN 및 25kN으로 증가시켰을 때 사전이도량의 변화를 계산하여보았다. 그리고 경부 2단계 구간 현장에서 실제 장력 증가 실험을 실시하여 사전이도량의 변화를 측정하였다. 측정 결과는 계산 값과 비교 검토를 수행하였으며, 결론적으로 전차선 장력을 증가시켜도 기하학적 형상의 변화는 미미하며 집전 성능에 별 영향이 없을 것임을 확인하였다.

• 대한조선학회논문집
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• 제32권3호
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• pp.83-97
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• 1995

본 논문의 목적은 종굽힘모멘트를 받는 선각거더의 최종강도를 계산하는 간이식을 도출하는 것이다. 먼저 기 제안된바 있는 계산식들을 조사 분석하였으며, 지금까지의 계산식 도출방법을 크게 해석적 방법, 경험적 방법 및 선형근사법의 3종류로 분류하였다. 선각거더는 종굽힘모멘트의 증가와 함께 압축플랜지의 붕괴와 인장플랜지의 항복에 의해 전체적으로 최종강도에 도달한다고 알려져 있다. 이때 선측부도 압축플랜지 부근에서는 붕괴하며, 인장플랜지 부근에서는 항복상태에 도달해 있는 경우가 많다. 그러나, 중립축부근에서는 여전히 탄성상태에 남아있는 것이 보통이다. 이같은 사실을 근거로 선각 횡단면에 걸쳐 적절한 응력분포를 가정하였으며, 이것으로부터 최종강도 계산식을 해석적인 방법으로 도출하였다. 본 계산식의 정도는 기존의 모형실험 및 수치해석결과와 비교하여 검증하였다.

• 한국해양공학회지
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• 제8권1호
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• pp.41-49
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• 1994

The leak-before-break(LBB) design on the large structures such as ship's hull, tank structure, pressure vessels etc. is one of the most inportant subjects for the evaluation and the assurance of safety. In these structures, various loads are acting. In some structural members, therefore, out-of-plane stress due to bending often may become with in-plane stress due to stretching. In the present report, the characteristics of fatigue life and peneration behaviour from a surface cracked plate under combined tension and bending have been studied experimentally and analytically by using eccentricity. Estimation of fatigue crack growth was done with the Newman-Raju formula before penetration, and with the stress intensity factor after penetration proposed by the author. Calculated aspect ratio showed the good agreement with the experimental result. It was also found that particular crack growth behaviour and crack shape after penetration can be satisfactorily evaluated using the K solution proposed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 봄 학술발표회 논문집
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• pp.108-115
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• 1990

This paper contains experimental studies on the flexural cracking behabior of PPC one-way slabs. Three post tensioned bonded PPC slabs with the same prestressing ratio and ultimate moment strength were tested. Based upon test results, this paper also presents the crack width prediction formula PPC slab. According to the crack theory developed mainly in Europe, crack width formula is given as the product of crack spacing and mean steel strain after decompression. Aaaaverage crack spacing formula is composed of many factors mainly such as concrete cover, concrete effective area in tension, sum of reinforcing bars perimeters and mixed reinforcements. In particular, it is very important to specify the bond characteristics of mixed reinforcements, since bond characteristics of PC bars are different from those of non-tensioned deformed bars. For this reason, a reduced bond coefficients for PS bars is employed in this study.

• Earthquakes and Structures
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• 제3권3_4호
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• pp.271-295
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• 2012

This paper presents the solution scheme of using the continuous formulation of 1-D linear member for the dynamic analysis of structures consisting of axially loaded members. The context describes specific applications of such scheme to the verification of experimental data obtained from field test of bridges carried out by a microwave interferometer system and velocimeters. Attention is focused on analysis outlines that may be applicable to in-situ assessment for cable-stayed bridges. The derivation of the dynamic stiffness matrix of a prismatic member with distributed properties is briefly reviewed. A back calculation formula using frequencies of two arbitrary modes of vibration is next proposed to compute the tension force in cables. Derivation of the proposed formula is based on the formulation of an axially loaded flexural member. The applications of the formulation and the proposed formula are illustrated with a series of realistic examples.

• 한국해양공학회지
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• 제16권5호
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• pp.49-55
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• 2002

The compression anchor is characterized by decrement of progressive failure, simple site work, economy and durability compared with tension anchor. In this paper, compression anchor is analysed through the laboratory element tests. The formula to be estimate the grout strength in fixed part of compression anchor and the effective reinforcement method for several types of soil were suggested. The following conclusions were made from this study : (1) A formula, which is able to calculate the grout strength in the fixed part of the compression anchor, is suggested. (2) The strength increment ratios( $R_{si}$) are 100％, 132％, 147％, 217％ according to the reinforcement method of grout. The reinforcement method is Non, Outside spiral, Inside-Outside spiral, Steel pipe, respectively. (3) The strength increment ratios( $R_{si}$) by reinforcing can be 8.23 times the strength increment effect according to the reinforcement types and ground confining pressure. (4) The steel pipe reinforcement is most effective in decomposed soil while, in the case of hard rock ground, high confining pressure is exerted on the grout, so there is no need to use reinforcements.

• Structural Engineering and Mechanics
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• 제12권5호
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• pp.459-474
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• 2001

The complete moment-curvature curves of doubly reinforced concrete beams made of normal- or high-strength concrete have been evaluated using a newly developed analytical method that takes into account the stress-path dependence of the constitutive properties of the materials. From the moment-curvature curves and the strain distribution results obtained, the post-peak behavior and flexural ductility of doubly reinforced normal- and high-strength concrete beam sections are studied. It is found that the major factors affecting the flexural ductility of reinforced concrete beam sections are the tension steel ratio, compression steel ratio and concrete grade. Generally, the flexural ductility decreases as the amount of tension reinforcement increases, but increases as the amount of compression reinforcement increases. However, the effect of the concrete grade on flexural ductility is fairly complicated, as will be explained in the paper. Quantitative analysis of such effects has been carried out and a formula for direct evaluation of the flexural ductility of doubly reinforced concrete sections developed. The formula should be useful for the ductility design of doubly reinforced normal- and high-strength concrete beams.