• 대한조선학회논문집
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• 제56권3호
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• pp.187-199
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• 2019

In the case of gas carriers and oil tankers, pipes are installed on the upper deck as a moving passage to load LPG, LNG, crude oil, etc. Pipes used for loading or unloading liquid cargo in cargo holds are connected to the hull through support structures. However, many cases of hull damage have been reported where the various equipment and support structures are installed on the upper deck. It is assumed that not only the structural discontinuity where the hull and the pipe support structure meet, but also action due to the pipe loads and the hull girder bending moment are simultaneously affected. This paper deals with the design and strength evaluation of the support structure of pipes and cables installed on the upper deck of commercial ships and offshore structures. For these supporting structures, design conditions and working loads were defined. The design procedure was established through the structure analysis on the method of determining the member dimensions. A series of finite element analysis was performed on the factors to be considered in the design and the effects were discussed. The accuracy and design periods of the strength evaluation was improved and reduced by application of the automation program in the finite element analysis. It is also expected that the design reliability of the shipyard is improved.

• 대한토목학회논문집
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• 제28권4A호
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• pp.465-474
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• 2008

일반적으로, 보-기둥 부재로 구성된 강뼈대구조물의 설계는 개별부재의 유효좌굴길이를 고려하여 설계기준에서 제시한 안정성 평가식을 적용하고 있다. 그러나 이 방법은 구조물에서 상대적으로 작은 압축력이 적용되는 부재에서는 유효좌굴길이가 커지는 문제가 발생하게 된다. 이러한 문제를 극복하고자 본 연구에서는 대상 구조물의 초기결함(initial imperfection)을 고려한 2차 탄성해석법을 제시한다. 이 방법은 탄성좌굴 고유치해석으로 산정된 좌굴모드 및 좌굴고유치, 개별부재의 축력을 이용하여, 가장 작은 무차원 세장비를 가진 부재를 선정하고, 그 부재에 대하여 기하적, 재료적인 효과가 고려된 설계기준의 기준강도곡선으로부터 좌굴모드에 대한 증폭량을 산정한다. 이렇게 결정된 증폭량을 대상 구조물의 좌굴모드에 증폭시켜 2차 탄성해석을 수행하고, 개별부재의 안정성을 평가한다. 본 방법의 타당성을 확인하기 위하여, 8층 및 4층으로 이루어진 평면 강뼈대구조물에 적용시키고, 설계기준에서 제시하는 안정성 평가법과 비교한다.

• 한국철도학회논문집
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• 제5권2호
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• pp.118-124
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• 2002

The failure probability of wheel beyond 10$\^$7/ cycles is achieved by the strengths-stress interference model for the evaluation of fatigue strength and reliability in the wheel, From plane bending fatigue test results, the fatigue life (N$\_$f/) for the smooth and 200㎛ holed specimens can be represented as $\sigma$$\_$a/ = 1326N$\_$f/$\^$-0.10/ and $\sigma$$\_$a/ = 2894N$\_$f/$\^$-0.18/. Respectively, fatigue strength of the wheel at beyond 10$\^$7/cycles was about 332 MPa. And, the fatigue strength for the specimen with a micro hole (d=200㎛) which simulated an inclusion on the wheel surface was about 235 MPa. Thus, a micro hole (d=200㎛) caused about 30% reduction of fatigue strength of the specimen. The failure probabilities for the smooth and micro-holed specimens, derived from the strength-stress interference model, are 0.0148% and 13.05%, respectively. The current finding suggests that at least 200 ㎛ sized inclusion, which might be produced during manufacturing process, will cause a critical effect on integrity of the railway vehicle.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.220-226
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• 1998

In this pater, a method of strength evaluation applying fracture mechanics in adhesively bonded joints of A1/A1 materials was investigated. Various adhesively bonded joints of double-cantilever beam with a interfacial crack in its adhesive layer were prepared for the fracture toughness test of comprehensive mixed mode conditions from nearly pure mode I to mode II. The experiment of fracture toughness was carried out under various mixed mode conditions with an interfacial crack and critical energy release rate, Gc by the experimental measurements of compliances was determined. From the results, fracture toughness on mixed mode with an interfacial crack is well characterized by strain energy release rate and a method of strength evaluation by the fracture toughness in adhesively bonded joints of A1/A1 materials was discussed.

• 대한기계학회논문집A
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• 제21권8호
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• pp.1322-1331
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• 1997

A method of strength evaluation applying fracture mechanics in the adhesively bonded joints of Al/Steel dissimilar materials was investigated in this paper. Various shapes of adhesively bonded Al/Steel scarf joints focussing on fracture criterion of mixed mode crack were prepared for the static tests. Also, stress intensity factors of the interface cracks in adhesively bonded joints of Al/Steel dissimilar materials were analyzed with 2-dimensional elastic program of boundary element method(BEM), and the experiment of fracture toughness were carried out under various mixed mode conditions. From the results, the fracture criterion and method of strength evaluation by the fracture toughness in adhesively bonded joints of Al/Steel dissimilar materials were proposed.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.233-238
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• 1998

Recently, the uses of ceramic/metal bonded joints for structural materials have increased in various engineering fields such as automobiles, heat engines, and so on. A method of strength evaluation focussing on fracture criterion of mixed was investigated in Si3N4/metal bonded joint. Also, Fracture toughness tests of Si3N4/metal bonded joints with an interface crack were carried out and the stress intensity factors of these joints were analyzed by boundary element method. From the results, the fracture criterion and method of strength evaluation by the fracture toughness were proposed in Si3N4/metal bonded joints

• Journal of Welding and Joining
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• 제13권4호
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• pp.103-112
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• 1995

This study was performed to optimize friction welding conditions of Cr-Mo steel bars used for hydraulic of pneumatic valve spools and to realize the real-time evaluation of weld quality by acoustic emission method. SNCM220, SCM435, SCAM645, and SCM415 steel bars were tested to find optimum conditions of friction welding. Auantitative equations which exhibit the relations of tensile strength, elongation, reduction of area and energy absorption with friction heating time were obtained by the experiment. Acoustic emission was also performed in the friction weldig process, and the real-time evaluation was enabled to find the optimum range of weld strength. Finally, the strength and toughness of welded joints were interpreted by the sem analysis of tensile fracture surfaces.

• 한국터널지하공간학회 논문집
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• 제18권2호
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• pp.165-173
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• 2016

본 논문은 격자지보재의 규격자재와 비규격자재의 성능평가에 대한 내용을 다루었다. 격자보재는 강봉으로 제작된 아치형의 터널지보공을 말하며 터널 굴착시 지반의 변형을 최대로 억제하여 터널의 안정성을 확보하기 위하여 사용되어지는 지보재이다. 이런 격자지보재의 성능평가는 휨강도시험과 인장강도시험을 통해 평가할 수 있으며 터널표준시방서에서는 항복강도 500MPa 이상인 용접용 강재를 사용도록 규정하고 있다. 그러나 저품질의 강재가 사용될 경우 현장에서 규격자재와 비규격자재를 육안으로 구분하기 어렵게 되었다. 따라서 본 논문에서는 격자지보재의 규격자재와 비규격자재에 대한 성능평가를 실시하여 비규격자재의 항복강도 저하의 문제점을 분석하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.69-74
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• 2001

Steel plate or fiber composite plate are mainly used in externally bonding method. Shear strengthening by externally bonding method is to confirm shear safety and to avoid brittle failure. In case of strengthening by externally bonding method, a failure of structure occurs frequently due to delamination between strengthening plate and concrete. Therefore, it is important to consider the delamination in the strengthening design. The objective of this study is to propose a modified shear strength evaluation by considering the delamination. The delamination criteria of strengthening plate is established by the ultimate strain and shear stress. And shear strength of RC beams is proposed in terms of the delamination criteria. The proposed shear strength is compared with test results and verified through the comparison.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.20-27
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• 1998

According as the member of the automobile body structure have been thinned their thickness and have become high strength, each part of the body structure has been put more severe stress condition. And, because fatigue strength of the spot welded lap joint is influenced by its geometrical and mechanical factors, welding condition and etc., there needs a quantitative and systematic evaluation method for them. In this study, by considering nugget edge of the spot weld part of the IB-type spot welded lap joint under tension-shear load to the ligament crack. fatigue strength of various IB-type spot welded lap joints was estimated with the stress intensity factor(S.I.F.) KIII which is fracture mechanical parameter. We could find that fatigue strength evaluation of the IB-type spot welded lap joints by KIII is more effective than the maximum principal stress ($\sigma$1max) at edge of the spot weld obtained from FEM analysis.