• 대한기계학회논문집A
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• 제40권12호
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• pp.1077-1085
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• 2016

선형 롤러베어링은 하중이 크고 정밀성이 요구되는 이송장치를 지지하기 위해 광범위하게 사용되는 기계요소이다. 본 논문에서는 외력을 받는 선형 롤러베어링의 변위를 계산하기 위한 새로운 모델링 방법을 제시하였다. 먼저 LM 블록을 강체로 가정하여 롤러와 LM 블록의 지배방정식을 유도하였고 Newton-Raphson법을 이용해 계산하였다. 롤러와 레이스 사이의 접촉하중은 롤러의 형상을 고려하여 슬라이싱 기법을 이용하여 계산하였다. 강체 LM 블록 모델에 의해 계산된 접촉하중을 활용하여 LM 블록의 구조적 변형을 유한요소 모델로부터 계산하였다. 최종적인 변위는 강체 LM 블록을 가정한 모델로부터 계산된 변위와 LM 블록 구조해석 결과를 조합하여 도출하였다. 제안된 방법에 의한 결과와 베어링 제작 업체 프로그램 결과와의 비교를 통해 제안된 방법을 검증하였다.

• Earthquakes and Structures
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• 제24권3호
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• pp.217-235
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• 2023

Orthogonal pairs of rollers on concave beds (OPRCB) are a low-cost, low-tech rolling-based isolating system, whose high efficiency has been shown in a previous study. However, seismic performance of OPRCB isolators has only been studied in the two-dimensional (2D) state so far. This is while their performance in the three-dimensional (3D) state differs from that of the 2D state, mainly since the vertical accelerations due to rollers' motion in their beds, simultaneously in two orthogonal horizontal directions, are added up and resulting in bigger vertical inertia forces and higher rolling resistance. In this study, first, Lagrange equations were used to derive the governing equations of motion of the OPRCB-isolated buildings in 3D. Then, some regular shear-type OPRCB-isolated buildings were considered subjected to three-component excitations of far- and near-source earthquakes, and their responses were compared to those of their fixed-base counterparts. Finally, the effects of more realistic modeling and analysis were examined by comparing the responses of isolated buildings in 2D and 3D states. Response histories were obtained by the fourth-order Runge-Kutta-Nystrom method, considering the geometrical nonlinearity of isolators. Results reveal that utilizing the OPRCB isolators effectively reduces the acceleration response, however, depending on the system specifications and earthquake characteristics, the maximum responses of isolated buildings in the 3D state can be up to 40% higher than those in the 2D state.

• 한국인쇄학회지
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• 제6권1호
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• pp.67-74
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• 1988

Absorption rates of oxygen in water soluble inks on the printing rollers were measured. As a results of experiments, could be obtained the data of rates of absorption of oxygen in 4 kinds of water soluble inks, and found the difference of absorption rate of oxygen on the parallel plates and rotating rolles.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 동계 학술대회 논문집
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• pp.266-271
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• 2000

• 소성∙가공
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• 제23권2호
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• pp.103-109
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• 2014

Flexibly-reconfigurable roll forming (FRRF), which is a sheet forming process for multi-curved sheet metal, may solve both the economic and technical problems incurred in using a conventional die forming process. In the FRRF process, the multi-curved sheet metal is formed by different strain distributions on the sheet metal, and the reconfigurable rollers are used as tools during the forming. Therefore, a thorough investigation focused on the reconfigurable rollers is required for the realization of the FRRF process prior to the fabrication of FRRF machine. In the current study, a series of finite element simulations were conducted to study the load distributions experienced by the reconfigurable roller. In order to verify the shape design variables, the effect of the metal thickness on the curvatures of sheet is also presented.

• 한국생산제조학회지
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• 제21권2호
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• pp.316-323
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• 2012

In order to meet the service life of planetary gearbox, a planet bearing, well known as the component with the highest failure rate, is designed. To predict the bearing fatigue life, ISO standard(ISO/TS 16281) is used, and the design parameters of the bearing are optimized using a parametric method. The whole planetary gearbox model is developed using a commercial software to calculate loads acting on planet bearings accurately. The results state that the designed bearings are satisfied with the life of 15,000hours, and the bearings that consist of 22rollers of 58mm have 1.6times longer life and better load sharing relatively than 22rollers of 28.5mm. Also, the increase in preload of taper roller bearings on the output pinion shaft prolongs the life of planet bearings regardless of roller's length.

• 한국가스학회지
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• 제18권1호
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• pp.41-45
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• 2014

본 연구에서는 원통형 중공롤러의 변위거동 안전성에 대한 해석적 연구를 수행하였다. 세 개의 튜브들 사이에 Y형상을 갖는 컬럼 구조물을 설치한 중공롤러를 개발하여 유한요소법으로 변형거동 안전성을 해석하였다. 동일한 크기와 중량을 갖는 두 개의 중공롤러 모델에 대한 해석결과에 의하면, 기존의 중공롤러는 세 개의 튜브 사이에 새로이 설계된 Y형상을 갖는 컬럼을 설치한 중공롤러에 비해 4~6.6% 낮은 변형거동 안전성을 보여주고 있다. 따라서 본 연구에서는 중공롤러의 강도 안전성을 높이고, 전체적인 중량을 낮춰 소비되는 전기에너지를 줄이기 위해서는 Y형상 컬럼을 설치한 새로운 중공롤러를 사용하는 것이 바람직함을 알 수 있다.

• 한국유체기계학회 논문집
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• 제19권5호
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• pp.28-34
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• 2016

Though a peristaltic pump is a crucial element in miniaturized drug delivery systems, it has some intrinsic disadvantages such as backflow and flow fluctuation. To overcome these limitation, we have developed valve-less peristaltic pump system including orifice and stagnation chamber. we measured flow rate to investigate the performance of rotary peristaltic pump with three rollers and an elastomeric tube pumping a viscous fluid. The flow fluctuations and the backflow happen as a result from the disengagement of the contact interaction between the rollers and the tubes. Stagnation chamber installed in front of orifice plate was composed of rubber tube and gas chamber. By changing orifice hole diameter with stagnation chamber flow rate and pressure in the tube was regulated. The obtained maximum reduction ratio of flow fluctuation is 96.79%.

• 대한기계학회논문집A
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• 제33권11호
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• pp.1217-1224
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• 2009

This paper presents a finite element (FE) analysis of the torsional rigidity of a two-stage cycloid drive. The cycloid disk makes contact with a number of pin-rollers simultaneously and eccentric shafts transmit not only torque of the spur gear stage to the cycloid disk, but also that of the cycloid disk to the output disk. Contacts between the disk and pin-rollers are simplified as linear spring elements, and the bearing of eccentric shaft is modeled as a rigid ring that has frictional contact to the disk and an elastic support. FE analysis for an ideal solid cycloid drive was performed and verified by a theoretical calculation. Accurate contact forces were then estimated by iterating between FE analysis for contact forces and Hertz theory calculations for nonlinear contact stiffness. In addition, torsional rigidity of the cycloid drive is analyzed to show that the bearing and nonlinear Hertz contact theory should be considered in analysis and design of a cycloid drive, which was verified with experiments. Finally, the effects of contact stiffness, bearing stiffness and cycloid disk structural stiffness according to the cycloid disk rotation on the torsional rigidity were investigated.

• International Journal of Control, Automation, and Systems
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• 제1권4호
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• pp.484-494
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• 2003

In this paper, we describe a hydraulic system design and vehicle dynamic modeling for development of tire roller traction, an essential aspect in the system analysis of tire rollers. Generally, tire rollers are one of the most useful types of machines employed in road construction, technically applied to many construction fields. We also conceptualize a new hydraulic and driving system as well as define the motion equations for dynamic and hydraulic analysis. First, we design the hydraulic circuit of the steering control and driving machine system, which can be employed to advance the performance of the lateral control, creating a prototype of construction equipment. Second, we formulate the hydraulic steering system model and hydraulic driving system model through tire roller system development technology. Finally, we validate the acquired performance results in actual tire roller equipment using the data acquisition system. These results may perhaps facilitate the establishment of priorities and design strategies for incremental introduction of tire roller technology into the vehicle and construction field.