• 한국생산제조학회지
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• 제8권2호
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• pp.73-79
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• 1999

Most of mechanical structures are combined of substructures such as beams and/or plates. There are few systems with unibody structures but are many systems with united body structures. Generally the dynamic a nalysis of whole structures is performed under alternation load. In the structure design, the analysis of each bolted joint is more important than others for zero severity. This paper presents the analysis method of contact stress distribution factor in the bolted joint with variable fastening torque on joints in the structure. At first, a static vibration test was performed to find out a nominal stress of bolt jointed plates from the relationship between natural frequency and nominal stress. Then a contact stress was computed at contact point between bolt and plate in the structure. It is believed that the proposed method has promisiong implications for safer design with index of contact stress distribution factor and has merits for cost-down and saving time at the beginning of vehicle development.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.561-566
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• 2000

A screw driver is essentially used in assembling machine parts and electronic products such as the printed circuit board with a housing. As the parts to be assembled becomes small and precise, the higher precision of the controling screw driver torque is required. However, because the operator controls the fastening torque by his experience, it must be inexact. Thus the screw driver which can exactly control the fastening torque by a bellows is designed and developed in the study. The bellows is expanded by the inner air pressure and contracted and by the spring operation. The bellows driver is composed of the entrance solenoid valve, the exit solenoid valve and the pressure sensor. The pressure sensor senses the bellows pressure. When the pressure sensor output reaches the setting value, it operates the exit solenoid valve not to deliver further torque by letting the air of the bellows out. Through a series of experiments, the performance is studied and verified.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.194-201
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• 2002

In this study is presented a numerical method which assesses running safety of the freight car loading with loom CWR and structural safety of conventional railway track and fastening when passing over sharp curves and steel girder bridges. Optimal speed of the freight car is suggested based on the numerical reviews of the safety against derailment of the freight car and structural safety of track and fastening at vulnerable points of the conventional line.

• 한국공작기계학회논문집
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• 제10권5호
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• pp.53-59
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• 2001

A screw driver is widely used in assembling machine parts or electronic products such as the printed circuit board with a housing. As the parts to be assembled becomes small and precise, the higher precision of the controlling screw driver torque is required. However, because the operator controls the fastening torque based on experience, it must be inexact and the setting procedure will be time consuming job. Thus the screw driver which can exactly control the fastening torque is developed utilizing a bellows in this paper. The bellows is expanded by the inner air pressure and contracted by the spring operation. The bellows type driver is composed of a clutch mechanism with two solenoid valves and a pressure sensor. Those valves are controlled using the detected bellows pressure by the sensor. When the pressure reaches the setting value, the exit solenoid valve is opened to release the air pressure from the bellows so as not to deliver further torque. Through a series of experiments, the performance is examined and verified.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8812-8819
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• 2015

콘크리트 궤도 건설의 증가로 인한 레일 체결장치의 중요성이 커지고 있는 상황에서 최근 레일 체결장치의 부속품인 텐션클램프가 절손되는 사고가 발생되었다. 이는 현장상태, 운영기관, 열차운행조건 및 빈도 등 다양한 요인에 의한 것으로 텐션클램프의 거동관련 연구가 필요하다. 본 논문에서는 실내실험 및 유한요소해석을 통해 텐션클램프의 역학적 거동을 분석하였다. 실내실험을 수행하여 텐션클램프 체결력에 따른 응력 및 변위를 도출하고 이를 유한요소해석 결과와의 비교를 통해 해석 모델을 검증하였다. 또한 검증된 모델을 적용하여 열차 하중에 따른 텐션클램프의 변형과 응력을 도출하고, 응력 분석을 통해 텐션클램프의 피로에 대한 취약도를 파악하였다.

• Ocean Systems Engineering
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• 제6권2호
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• pp.143-159
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• 2016

Cargo, such as a Tension Leg Platform (TLP), Semi-submersible platform (Semi), Spar or a circular Floating Production Storage and Offloading (FPSO), are frequently dry-transported on a Heavy Lift Vessel (HLV) from the point of construction to the point of installation. The voyage can span months and the overhanging portions of the hull can be subject to frequent wave slamming events in rough weather. Tie-downs or sea-fastening are usually provided to ensure the safety of the cargo during the voyage and to keep the extreme responses of the cargo, primarily for the installed equipment and facilities, within the design limits. The proper design of the tie-down is dependent on the accurate prediction of the wave slamming loads the cargo will experience during the voyage. This is a difficult task and model testing is a widely accepted and adopted method to obtain reliable sea-fastening loads and extreme accelerations. However, it is crucial to realize the difference in the inherent stiffness of the instrument that is used to measure the tri-axial sea fastening loads and the prototype design of the tie-downs. It is practically not possible to scale the tri-axial load measuring instrument stiffness to reflect the real tie-down stiffness during tests. A correlation method is required to systematically and consistently account for the stiffness differences and correct the measured results. Direct application of the measured load tends to be conservative and lead to over-design that can reflect on the overall cost and schedule of the project. The objective here is to employ the established correlation method to provide proper high-frequency responses to topsides and hull design teams. In addition, guidance for optimizing tie-down design to avoid damage to the installed equipment, facilities and structural members can be provided.

• 비파괴검사학회지
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• 제34권1호
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• pp.38-43
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• 2014

굽힘파 전파 특성을 이용하여 지지강성을 도출하고 이를 이용한 레일체결장치의 결함 검출 시험법을 제안하였다. 점탄성 패드로 지지되고 체결장치로 고정된 레일의 진동 응답은 주파수에 따라 지지단 동특성에 크게 영향을 받는다. 체결장치에 결함이 발생할 경우에는 구조적인 불연속성으로 인해 굽힘 파동의 전파 특성이 변화하게 된다. 이러한 변화를 감지하기 위해서 전달함수법을 이용해 주파수에 따라 변화하는 레일 지지단 동특성을 측정하였다. 연속 스프링으로 지지된 레일 응답으로부터 예측한 레일의 보존에너지를 이용해 결함에 대한 파동 전파의 민감도를 해석하였다. 민감도 해석 결과와 동적지지강성 변화를 측정하여 손상지수를 계산하고 결함 위치를 추정하였다.

• Structural Engineering and Mechanics
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• 제86권2호
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• pp.261-276
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• 2023

The use of the ordinary double nut (i.e., ODN) composed of a master nut (i.e., M-nut) and a slave nut (i.e., S-nut) is a highly efficient method to prevent bolts loosening. A novel double nut (i.e., FODN) composed of a master nut (i.e., M-nut) and flat slave nut (i.e., FS-nut) is proposed to save raw materials. The bolt fastening tests with single nut, ODN and FODN are performed to investigate the preload and counterbalance forces. Corresponding finite element analysis (FEA) models are established and validated by comparing the preload with the experimental results. The load-bearing capacity, the extrusion effect, and the contact stress of each engaged thread for ODN and FODN are observed by FEA. The experimental and simulated results revealed that the bolt fastening with double-nut has different load-transferring mechanisms from single-nut. Nevertheless, for double-nut/bolt assemblies, the FS-nut can provide load transfer that is like that of the S-nut, and the FODN is a reasonable and reliable fastening method. Furthermore, based on the theory of Yamamoto, a formula considering the extrusion effect is proposed to calculate the preload distribution of the double-nut, which is applicable to varying thicknesses of slave-nuts in double-nut/bolt assemblies.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.157-158
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• 2023

Doors that are opened and closed when entering or exiting a general building are connected to the door frame and open and close. They are equipped with door locking devices of various structures, and are either locked to the door frame for the closing operation or released from the door frame for the opening and closing operation. Here, a single-stage door binding device having a door latch that is independently disposed at the center of one axis of the door is commonly used. On the other hand, if the size of the door is over a certain size or if the door is medium to large, the opening and closing operation may not be performed smoothly with only a single stage binder, or the closing state may not be achieved stably during the closing operation. In particular, in the case of the single-stage binding device provided in medium to large fire doors, the door is fixed to the door frame unstable, causing fatal errors in the fire prevention function of the fire door. Accordingly, in order to fundamentally solve these problems, we researched and developed a three-stage door binding machine that combines a top and bottom fastening structure with a single-stage fastening structure. This 3-stage door binder not only has the fire resistance performance of a fire door, but also has a T-shaped terminal in its fastening method, so if you eliminate the upper and lower fastening, it is a 1-stage binder like a regular product, but if you remove the door latch of the 1st-stage binder, it functions as an upper and lower 2-stage binder and forms a single mold. We researched and developed a three-stage door binder that can manufacture and produce three products at the same time, satisfying both product performance and price.

• Journal of Welding and Joining
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• 제33권3호
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• pp.12-18
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• 2015

The ultimate goal of developing body is revealed the "lightweight" at latest EuroCarBody conference 2012 and the most core technology is joining process to make lightweight car body design. Accordingly, in this study, the car body assembly line for the assembly process applies to any introduction, particularly in the assembly of aluminum alloy and composite materials applied by the process for the introductory approached. Process were largely classified by welding (laser, arc, resistance, and friction stir welding), bonding (epoxy bonding) and mechanical fastening (FDS, SPR, Bolting and clinching). Applications for each process issues in the case and the applicable award was presented, based on the absolute strength of the test specimens and joining characteristics for comparative analysis were summarized. Finally, through this paper, we would tried to establish the characteristics of the joint for lightweight structure.