• Computers and Concrete
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• 제26권2호
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• pp.161-173
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• 2020

Shear keys in precast concrete segmental bridges (PCSBs) are usually match-casting which is very labour intensive. In this research, an innovative match-casting-free construction was proposed by leaving small gap between the convex and the concave castellated shear keys in the joints of PCSBs. Specimen experiment, shear strength analysis and numerical simulation were conducted, investigating the loading performance of this new type of dry joints, the gap dry joints. Compared with match-casting joint specimens, it has been found from experiment that shear capacity of gap joint specimens significantly decreased ranging from 17.75% to 42.43% due to only partially constrained and contacted in case of gap dry joints. Through numerical simulation, the effects of bottom contacting location, the heights of the gap and the shear key base were analyzed to investigate strength reduction and methods to enhance shear capacity of gap joint specimens. Numerical results proved that shear capacity of gap dry joints under full contact condition was higher than that under partial contact. In addition, left contact destroyed the integrity of shear keys, resulting in significant strength reduction. Larger shear key base remarkably increased shear capacity of the gap joint. Experimental tests indicated that AASHTO provision underestimated shear capacity of the match-casting dry joint specimens, while the numerical results for the gap dry joint showed that AASHTO provision underestimated shear capacity of full contact specimens, but overestimated that of left contact specimens.

• 한국구조물진단유지관리공학회 논문집
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• 제9권1호
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• pp.197-204
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• 2005

다목적 바닥 레벨조인트는 레일의 레벨링과 조립이 용이하고 조인트에서 변형 흡수가 가능한 공법으로 최근 국내에서 개발되었다. 앞서 수행된 연구결과를 통하여 본 공법의 구성부재인 지지대, 레일, 그리고 레일+지지대의 구조적 특성은 만족스런 결과를 얻을 수 있었다. 따라서 본 연구에서는 콘크리트를 타설한 바닥 레벨조인트의 변형흡수 능력을 평가하기 위해 인장 또는 압축변형을 유발시킨 실험적 연구를 실시하였다. 또한 다목적 바닥 레벨 조인트를 설치한 대상구조물을 선정하여 해석적 연구를 수행함으로서 다목적 바닥 레벨 조인트의 변형성능을 정량적으로 파악하였다. 실험과 해석연구를 통하여 다목적 바닥 레벨조인트는 요구되는 변형수요에 비하여 충분한 변형흡수 능력을 확보하고 있는 것으로 나타나났다.

• 한국표면공학회지
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• 제42권6호
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• pp.294-300
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• 2009

The Friction Stir Welding (FSW) has mainly been used for making butt joints in Al alloys. The development of Friction Stir Lap Welding (FSLW) would expand the number of applications. In this study, for effective application on thin aluminum alloy lap joint, non-heat treatment A5052 alloys were joined by FSLW with the length of probe 2.3 mm and 3.0 mm. Investigating the characteristics of joint area showed the results were as below ; When the length of probe was 2.3 mm, good joint area was formed at all welding condition except for 600 rpm-700 mm/min. In the case of 3.0 mm probe length, there was formed good joint area without defects at 1500 rpm-100 mm/min. The width of joint area, position and size of defects were very important factors for FSLW, due to heat input and stirring intensity.

• 한국정밀공학회지
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• 제28권11호
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• pp.1316-1322
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• 2011

Most of the mechanical structures use bolting or spot welding for the whole structure. In recent years, bolting & rivets are used rather than the welding due to reassembly and repair. Analysis of bolted joints is so complicate that many conditions must be considered such as pre-load and contact, etc.. Bolted joint analysis is done by theoretical, experimental & numerical methods. However, numerical analysis in the bolted joint is used because the contact and stress in the joints are changed due to the pre-load. In this study, we analysis the slip and the deformation of the contact area in the joint depending on the pre-load and find the optimized bolting condition.

• 접착 및 계면
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• 제7권4호
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• pp.13-17
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• 2006

The elasto-plastic finite element method (FEM) was used to investigate the effect of off-center recessing location (8 mm length) on the stress distribution in the lap zone of adhesively bonded aluminium double lap joint. The results from simulation showed that the effect of off-cent recessing in bondline of double lap joint in the mid-bondline is not evidently to stress distribution in mid-bondline but the peak stresses both in mid-bondline and in the interface near the adherend side of the joint may increase markedly when an 8 mm length recessing was arranged symmetrical to the point of x =18 mm. When shifting an 8 mm length recess from near left end to the right end of the lap zone, all the highest peak stresses in the mid-bondline occurred under the condition of recess arranged symmetrical to the point of x = 6 mm.

• 터널과지하공간
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• 제9권2호
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• pp.141-148
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• 1999

암반 내에 존재하는 절리의 분포 양상을 현실적으로 반영할 수 있는 개별요소해석에서, 절리의 거동을 모사하는 구성방정식의 적절한 선택이 해석결과에 미치는 영향은 매우 크다. 본 연구에서는 절리 암반 사면의 안정성 분석을 통하여 Barton-Bandits (BB)의 구성방정식과 Mohr-Coulom (MC)의 구성방정식을 비교해 보았다. 절리의 전단변위 발생에 따른 수직팽창을 허용하는 BB 모델에서는 현장의 사면 양상과 매우 유사한 결과를 도출하였으며, 그 결과 10cm 두께의 숏크리트 타설이 보강 방안으로 제안되었다. 반면, 수직팽창이 일정한 값으로 주어지는 MC모델에서는 외부 하중 조건에 대하여 둔감한 반응을 보이는 등 현장 상황을 충분히 예측하지 못하는 결과가 도출되었다.

• 대한정형도수물리치료학회지
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• 제20권1호
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• pp.35-38
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• 2014

Background: The case study examined the effect of a hip joint traction and hip posterolateral muscles strengthening on knee pain, range of motion, and lower extremity function scale of patients with patellofemoral pain syndrome (PFPS). Although PFPS has previously been attributed to quadriceps dysfunction, more recent research has linked this condition to impairment of the hip musculature and kinematic. Methods: Subject is a 27-years-old female with PFPS. Performed hip joint traction with belt and posterolateral muscles(hip abductors, external rotators) strengthening for 4 weeks, 3 times a week, once a day. Before and after the therapy, measurements were made on the visual analog scale (VAS) and of the ROM, and a lower extremity functional scale (LEFS) was conducted. Results: The results showed positive changes in VAS and range of motion and lower extremity functional scale. First VAS of knee changed from 6 to 2. Second hip joint range of motion showed that internal rotation recored from $53^{\circ}$ to $58^{\circ}$ and external rotation recorded from $32^{\circ}$ to $37^{\circ}$. Third The lower extremity functional scale showed before therapy of 44; after therapy, 63. Conclusion: The hip joint traction and hip posterolateral muscles strengthening was effective in alleviating knee pain, increasing ROM and Lower extremity functional scale of the PFPS patients.

• 한국해양공학회지
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• 제26권5호
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• pp.18-24
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• 2012

This paper concerned with the behaviour of shaping formation and the erection for SCST structure by cable-tensioning for three kinds of structure models. The joint types of experimental models are ball type joints, bolt type joints with gusset plates, and bolt type joints. The feasibility of the proposed shaping method and the reliability of the established geometric model were confirmed with a nonlinear finite element analysis and an experimental investigation for full size scaled pyramid test model and three kinds of SCST structure models. The characteristic of the behaviour of each joint type is shown in the shaping test for practical design purposes. As a results, the behaviour characteristics of joints is very significant in shaping analysis of space structures. So the joint type should be considered in the design and analysis of the shape formation for space structures. Also, in the special field condition, it could be a fast and economical method for constructing the space structure.

• Journal of Oral Medicine and Pain
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• 제46권3호
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• pp.69-74
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• 2021

As for temporomandibular joint arthritis (TMJ OA), managing the contributing factors at an early stage through accurate diagnosis is necessary to prevent irreversible bone changes. TMJ OA, which is a multi-organ disease caused by various pathophysiological mechanisms, is developed mainly due to mechanical overload. It is a disease characterized by degeneration of articular cartilage and subchondral bone as a low-level inflammatory arthritis condition developed by dysregulation of catabolic and anabolic activity of chondrocytes. Age, mechanical overload sensing of cartilage, chondrocyte apoptosis, catabolic enzymes, inflammatory factors, abnormal remodeling of subchondral bone, and estrogens may be involved in the pathogenesis of arthritis. Therefore, a comprehensive evaluation is needed to diagnose and manage progressive cartilage degeneration, subchondral bone remodeling, and associated symptoms of TMJ OA.

• Structural Engineering and Mechanics
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• 제77권3호
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• pp.383-394
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• 2021

Column foot in traditional Chinese timber structures may be subjected to be uplifted due to the lateral load and subsequently reset under the vertical loads. The residual moment of the rocking column foot is the most important parameter representing the mechanical behaviors of column foot, and the simplification of joints is the basis of structural analysis of whole structure. The complicated mechanical behaviors of joint and the modeling of the column foot joint has been undertaken historically based on the experiments and numerical simulation. On the condition of limited application range of those models, a lack of simplified model to represent the mechanical behaviors of joint deserves attentions. There is a great need to undertake theoretical studies to derive the residual moment and make better simplified model of the joint. This paper proposes the residual moment and equivalent simplified model of the rotational stiffness for column foot joint. And, the timber frame is established based on the simplified model, which is verified by solid finite element model. Results show that a mutual agreement on the mechanical behaviors of the timber frame is obtained between the simplified model and the solid finite element model. This study can serve as the references of the structural analysis for the traditional timber structures.