• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1188-1195
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• 2007

The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads, the settlement of supports, and the temperature gradients. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of various load cases, such as the end rotation of the overhang due to the vertical load, the bending of pier due to acceleration/braking force and temperature deviation, the settlement of embankment and pier, the temperature deviation of up-down deck and front-back pier, and the rail deformation due to wheel loads. The analysis of the rail fastener is made to verify the superposed tension forces in the rail fastener due to various load cases, temperature gradients and settlement of supports. The potential critical fasteners with the highest uplift forces are the fastener adjacent to the civil joint. The main influence factors are the geometry of the bridge such as, the beneath length of overhang, relative position of bridge bearing and fastener, deflection of bridge and the vertical spring stiffness of the fastener.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.279-282
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• 2008

The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of the end rotation of the overhang due to the vertical load. When the up-lifting force exceeds the clamp force of the fastener clip, the rail pad is out of fastener, which makes decrease the serviceability of the railway, such as noise and vibration. Furthermore, it is possible to reduce the safety of the track as the longitudinal resistance. This study is focused on guideline suggestion to decrease up-lifting force in the fastener adjacent to the civil joint of slab track of bridge throughout the parametric analysis between the vertical spring stiffness of the fastener as the material approach, the space of fastener adjacent to bridge transition, the rigidity of the girder as the geometrical approach and up-lifting force under the train load.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.447-454
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• 1999

In this paper, a technique for the shape design and analysis of rail fastener is presented. KRRI's own 3 type fasteners are developed after due consideration for tile aspects of installation, maintenance, and cost of fastener. Numerical by using commercial FEM program COSMOS/Works are carried out to determine the optimal shape of fastener clip. Front tile manufactured models and numerical results, the developed fasteners show tile possibility to be commercialized. But in order to have their competitiveness on the markets, further studies are required for the demonstration of performance through laboratory and field tests

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.800-806
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• 2011

Thermal expansion which occurs at the high speed rail joint is proportional to the free length from the point of fixity. This thermal expansion behaves similar to free expansion because the girder longitudinal stiffness is much larger than longitudinal resistance of rail pads. But the longitudinal displacement in the long rail is nominal because the longitudinal support condition of the girder is normally MFM(movable-fix-movable) system. Due to these girder expansion characteristics, there is longitudinal relative displacement at the rail pad and rail fastener spring which connects rail and girder. If the relative displacement between rail and girder is beyond the elastic limit for the rail pad, rail fastener system shall be applied using sliding fastener to prevent rail pad damage and fastener separation resulting from slip. On the other hand, train vertical vibration and tilting can occur due to the lack of fastener vertical force if the sliding fastener is applied at the girder joint. In the high speed rail bridge, vibration can occur due to the spring stiffness of the elastomeric bearing, also both vertical downward and upward displacement can occur. The elastomeric bearing vertical movement can cause rail displacement and finally the stability of the ballast is reduced because the gravel movement is induced.

• 한국전자통신학회논문지
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• 제11권1호
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• pp.107-112
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• 2016

나사는 산업의 모든 분야에서 널리 사용되는 중요한 부품이다. 최근에는 여러 가지 필요에 의해 다양한 칼라 나사가 출시되고 있다. 이에 따라 제조 공정상에서 실시간 품질 검사가 요구되고 있다. 본 논문에서는 칼라 정보와 동적 계획법(Dynamic Programming) 알고리듬을 이용한 칼라 나사 검사를 위한 표면 영역 자동 추출 알고리듬에 대해 다루도록 한다. 나사의 외곽 경계는 칼라 성분의 차이를 이용하여 보다 강인한 검출이 가능하도록 한다. 나사의 내부 경계는 직교 좌표계를 극좌표계로 변환후 흑백 이미지상에서 일정 영역의 밝기값 차이를 이용한 동적 계획법을 적용하여 추출하도록 한다. 실험에서는 동일한 인자값을 이용한 결과를 분석하도록 한다.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.659-667
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• 2017

Rail support failure is inevitably subjected to track geometric deformations. Due to the randomness and evolvements of track irregularities, it is naturally a hard work to grasp the trajectories of dynamic responses of railway systems. This work studies the influence of rail fastener failure on dynamic behaviours of wheel/rail interactions and the railway tracks by jointly considering the effects of track random irregularities. The failure of rail fastener is simulated by setting the stiffness and damping of rail fasteners to be zeroes in the compiled vehicle-track coupled model. While track random irregularities will be transformed from the PSD functions using a developed probabilistic method. The novelty of this work lays on providing a method to completely reveal the possible responses of railway systems under jointly excitation of track random irregularities and rail support failure. The numerical results show that rail fastener failure has a great influence on both the wheel/rail interactions and the track vibrations if the number of rail fastener failure is over three. Besides, the full views of time-dependent amplitudes and probabilities of dynamic indices can be clearly presented against different failing status.

• Structural Engineering and Mechanics
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• 제28권2호
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• pp.239-257
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• 2008

Double-sided punched metal plate timber fasteners present projections on both sides, which offer improved joint fire resistance and better joint aesthetics. In this paper, 3-D nonlinear finite element models were developed to simulate double-sided nail plate fastener timber joints. The models, incorporating orthotropic elasticity, Hill's yield criterion and elasto-plasticity and contact algorithms, are capable of simulating complex contact between the tooth and the timber and between the base plate and the timber in a fastener. Using validated models, parametric studies of the double-sided nail plate joints was undertaken to cover the tooth length and the tooth width. Optimal configuration was assumed to have been attained when increase in nail plate tooth width did not result in a raise in joint capacity, in conjunction with the optimum tooth length. This paper presents the first attempt to model and optimise tooth profile of double-sided nail plate fastener timber joints, which offers rational designs of such fasteners.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.304-310
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• 2001

Cracks at mechanical fastener holes usually nucleate as elliptical comer cracks at the faying surface of the mechanical joints and grow as elliptical arc through cracks after penetrating the opposite surface. In this study mode I, II and III stress intensity factors at two surface points of elliptical arc through cracks at mechanical fastener holes are analyzed by applying weight function method. The weight function method for two dimensional mixed-mode problem is extended to three dimensional one and it is verified.

• 한국염색가공학회지
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• 제29권3호
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• pp.162-170
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• 2017

Fastener tapes are widely used as auxiliary materials in textile products, and military textiles products are also applied. However, in Korea, the HL3-WA class of KS K 1309 was applied to military uniforms without consideration of the operating environment. Instead of adopting the standard of initial strength for Korean military uniforms, the US military applied the value after 3 washings, and presented different properties according to the items. Also in Japan, the standard was applied differently according to products in general clothing. The purpose of this study in to examine the quality level of fastener tapes used for military materials. The changes of tensile shear strength and peel strength of military and commercial fastener tape were studied after washing. As a result, the initial strength of the current military fastener tapes was higher than commercial one, but the strength retention rate was rapidly decreased as the number of washing. So it was confirmed that the decrease in strength was relatively lower than commercial one. It is necessary to improve the durability by adjusting the adhesive strength to suit the purpose of the product, and it is necessary to consider the priority of maintaining the durability according to the initial performance and repeated use according to the use environment, respectively.

• 한국강구조학회 논문집
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• 제26권3호
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• pp.231-240
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• 2014

축방향 인장력을 받는 T-stub은 T-stub과 긴결재의 재료적 물성 특성, T-stub의 기하학적 형상, 긴결재의 직경과 체결력 등의 변화에 의하여 상이한 거동특성을 나타낸다. 이러한 변화의 영향으로 T-stub은 T-stub 플랜지의 휨항복 후 소성파괴, T-stub 필릿부의 휨항복과 긴결재 파단, 긴결재의 파단 등과 같은 세 가지 파괴양상을 나타낸다. 일반적으로 T-stub 플랜지의 두께가 얇고 긴결재의 게이지 거리가 긴 T-stub은 플랜지의 휨항복 후 소성화에 의하여 T-stub 플랜지의 두께가 두껍고 긴결재의 게이지 거리가 짧은 T-stub보다 에너지소산능력이 우수하다. 이 연구는 T-stub 체결에 사용된 긴결재가 T-stub의 에너지소산능력에 미치는 영향을 파악하기 위하여 3차원 비선형 유한요소 해석을 진행하였다. T-stub 해석모델의 긴결재로는 F10T-M20 고장력볼트와 ${\varnothing}19.05mm$(3/4inch)인 SMA 강봉을 모델링하였고, T-stub의 기하학적 형상은 T-stub 필릿부의 휨항복과 긴결재 파단의 파괴를 나타내도록 선택하였다.