• 항공우주시스템공학회지
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• 제12권1호
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• pp.35-41
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• 2018

무인기는 관측, 통신중계, 정보 수집 등 여러 분야에서 다양한 목적으로 활용되고 있다. 최근 개발되는 무인기는 장시간 체공을 하면서 현재 수준보다 정밀하고 다량의 정보 수집이 가능하도록 고사양의 성능이 요구되고 있다. 현재, 국내에서는 인공위성의 일부 기능 대체를 목적으로 성층권에서 장기간 비행하기 위한 고고도 장기체공무인기가 개발되고 있다. 본 연구는 고고도 장기체공 무인기용으로 개발 중인 기체구조에 대한 구조 건전성 평가의 일환으로 동체 및 미익 체결부에 대한 안전여유 계산을 통하여 구조 건전성을 평가하였다. 그 결과로, 개발 중인 무인 비행체의 기체 구조 체결부에 대한 설계 타당성을 확인하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제26권4호
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• pp.11-19
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• 2022

본 연구에서는 기계식 커플러의 이음성능을 향상시키기 위해 다른 접합방식을 가진 두 가지의 새로운 커플러를 개발하였다. 두 가지 방식의 기계식 이음장치에 대하여 응력 해석을 수행하였다. 커플러의 재료특성, 접합방식, 내부 조임쇠의 경사길이를 변수로 최대 인장강도의 영향성을 분석하기 위해 일축인장시험을 수행하였다. 일축인장시험결과를 만족하는 시험체를 대상으로 KS D 0249에 의거하여 정적내력시험 및 반복하중 시험을 수행하였다. 이에 대한 연구결과는 다음과 같다. (1) 커플러의 인장강도와 내부 조임쇠의 경사길이는 최대 인장강도에 영향을 끼친다. (2) 연결 방식에 따라 접합된 철근의 강성, 슬립량, 강성감소율에 영향이 있다. 연구결과는 새롭게 제안된 향상된 기계식 이음장치의 현장 적용에 대한 가능성을 검증하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.19-20
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• 2009

• Journal of the Korean Wood Science and Technology
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• 제20권1호
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• pp.15-22
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• 1992

This study was performed to investigate the corrosion of metal fasteners in waterborne preservative-treated wood. Of all the metal tested, steel exhibited the greatest amount of corrosion across all preservatives and exposure conditions whereas stainless steel was totally inert. Galvanized steel corroded at a much lower rate compared to steel and the corrosion of brass was negligible. Among the preservatives, CCA-Type B was the most corrosive system tested. The sequence for the average corrosivity across all metals was: CCA-type B>CCA-Type C${\geq}$ACC${\geq}$CCA-Type A. Across all metals and retentions the salt formulations were more corrosive than the oxide and the corrosion was increased with the increse in the amount of preservative loadings. The amount of corrosion was also increased with the increase in exposure relative humidity (RH) across all metals and presevatives However, at the 60% RH exposure condition, the corrosion of metals was very negligible. Consequently, it can be concluded that across all metals oxide-type preservatives should be used to prevent the corrosion problem of metal fasteners in contact with treated wood and the use of steel nail preservative-treated wood should be avoided without distinction of end-use location, i.e., exterior or interior, and the use of stainless steel or at least brass nail in damp exterior condition was strongly recommended.

• Steel and Composite Structures
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• 제29권2호
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• pp.219-229
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• 2018

This paper presents an analytical model to analyze the mapping relationship between bridge lateral deformation and track geometry of high-speed railway. Based on the rail deformation mechanisms, the deformation of track slab and rail at the locations of fasteners are analyzed. Formulae of rail lateral deformation are derived and validated against a finite element model. Based on the analytical model, a rail deformation extension coefficient is presented, and effects of different lateral deformations on track geometry are evaluated. Parametric studies are conducted to evaluate the effects of the deformation amplitude, fastener stiffness and mortar layer stiffness on the rail deformation. The rail deformation increases with the deformation of the girder, and is dependent on the spacing of the fasteners, the elastic modulus of the rail's material, and the moment of inertia of the rail's section.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.326-331
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• 2005

In this study, bearing response in single lap riveted joint is investigated by menas of single lap shear specimens with different types of adherend and fastener. Single lap shear specimen consists of adherend of SUS403 and carbon fabric/epoxy composite. Rivet of Avdel 2691 with 9.6mm diameter is used. Two types of fastener in single lap riveted joint are considered. One is a single lap shear specimen with single fastener, and the other is a single lap shear specimen with double fasteners. Especially, in case of single lap shear specimen with single fastener, the width of the specimen is varied as 2D, 3D, 4D, 6D at a fixed edge distance of 3D. Also the edge distance of the specimen is varied as 1.0D, 1.5D, 2.0D, 2.5D, 3.0D at a fixed width of 4D. In case of single lap shear specimen with double fasteners, two types of specimen are considered. One is a specimen with the width of 6D and edge distance of 3D. The other is a specimen with the width of 4D and edge distance of 2D. Here D designates the hole diameter for riveted joint.

• 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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.148-152
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• 2000

The aluminum alloy 6061-T6 has been successfully used in structural applications especially the pressure vessel of the Advanced Neutron Source research reactor. And aluminum alloys, including 6061-T6, have a face-centered-cubic crystals structure. Under normal circumstances face-centered-cubic crystal structures do not exhibit cleavage fractures even at very lo9w temperatures. In aluminum-based structures, plates frequently find use as connecting links. Mechanical fasteners are often utilized in instances where ease of application, familiarity with fabrication processes, and severe dynamic loading are of concern. Plates frequently find use as connecting elements in structures built from aluminum alloys. Many structural elements employ mechanical fasteners. Twenty and twenty aluminum alloy 6061-T6 plates, representing four different bolt patterns, were mechanically deformed. And variable materials such as A1 6061-T6, Al 2024-T3, Carbon/Epoxy, Glass/Epoxy Composite and Woven fiber composite, are used as patch materials. From this experiment, it has been shown that the strength of patch-repaired specimens is different with the patch materials.

• Steel and Composite Structures
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• 제1권1호
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• pp.1-16
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• 2001

Due to aesthetic, economic, and structural performance, the use of structural hollow sections as columns in both continuous moment resisting and nominally pinned construction is attractive. Connecting the beams to these sections is somewhat problematic as there is no access to the interior of the section to allow for the tightening of a standard bolt. Therefore, bolts that may be tightened from one side, i.e., blind bolts, have been developed to facilitate the use of site bolting for this arrangement. This paper critically reviews available information concerning blind bolting technology, especially the performance of fasteners in shear, tension, and moment resisting connections. Also provided is an explanation of the way in which the results have been incorporated into design guidance covering the particular case of nominally pinned connections. For moment resisting connections, it is concluded that whilst the principle has been adequately demonstrated, sufficient data are currently not available to permit the provision of authoritative design guidance. In addition, inherent flexibilities in the connections mean that performance equivalent to full strength and rigid is unlikely to be achievable: a semicontinuous approach to frame design will therefore be necessary.

• Steel and Composite Structures
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• 제33권3호
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• pp.347-356
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• 2019

Most of the recent studies have improved the efficiency of FRP jackets for increasing the compressive strength, shear strength, and ductility of reinforced concrete columns; however, the influence of FRP jackets on the flexural capacity is slight. Although new methods such as NSM (near surface mounted) are utilized to solve this problem, yet practical difficulties, behavior dependency on adhesives, and brittle failure necessitate finding better methods. This paper presents the results of an experimental study on the application of fiber-reinforced polymer fastened mechanically to the concrete columns to improve the flexural capacity of RC columns. For this purpose, mechanical fasteners were used to achieve the composite behavior of FRP and concrete columns. The experimental program included five reinforced concrete columns retrofitted by different methods using FRP subjected to constant axial compression and lateral cyclic loading. The experimental results showed that the use of the new method proposed in this paper increased the flexural strength and lateral load capacity of the columns significantly, and good composite action of FRP and RC column was achieved. Moreover, the experimental results were compared with the results obtained from the analytical study based on strain compatibility, and good proximity was reached.