• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.277-280
• /
• 2001

The effects of a -phase morphology on the static and dynamic deformation behavior of a Ti-6Al-4V alloy was investigated in this study. Static tension test, static and dynamic tension test and hot compression test were conducted on three microstructures of Ti-6Al-4V alloy, i.e., equiaxed, widmanstatten and bimodal microstructures. Fracture surfaces of all three microstructures represented ductile fracture appearance, though the formation of adiabatic shear bands was noticed at dynamic torsion test. The susceptibility of forming adiabatic shear bands was greatest in the equiaxed microsoucture and lowest in the bimodal microstructure, which was evidenced by hot compression test.

• Ocean Systems Engineering
• /
• v.6 no.2
• /
• pp.203-216
• /
• 2016

Over recent years the offshore wind turbines are becoming more feasible solution to the energy problem, which is crucial for Egypt. In this article a three floating support structure, tension leg platform types (TLP), for 5-MW wind turbine have been considered. The dynamic behavior of a triangular, square, and pentagon TLP configurations under multi-directional regular and random waves have been investigated. The environmental loads have been considered according to the Egyptian Metrological Authority records in northern Red sea zone. The dynamic analysis were carried out using ANSYS-AQWA a finite element analysis software, FAST a wind turbine dynamic software, and MATLAB software. Investigation results give a better understanding of dynamical behavior and stability of the floating wind turbines. Results include time history, Power Spectrum densities (PSD's), and plan stability for all configurations.

• Journal of Ocean Engineering and Technology
• /
• v.33 no.2
• /
• pp.99-105
• /
• 2019

Unlike typical a dynamic positioning (DP) system, a DP-assisted mooring system must determine a set point (SP) that can ensure a mooring tension safety range to prevent an excessive increase in mooring tension. In this paper, a new algorithm for determining the SP is suggested in order to reduce the tension on all the mooring lines. To determine the SP, a working area around the vessel is represented by a rectangular grid. Thus, the size of the grid area is limited considering the offset of a vessel with a mooring system. At each grid's nodes, the resultant tension from all the mooring lines is estimated using the time history of the tension and vessel's position. The results of static analyses for each grid position are used to estimate the global tension. Consequently, the SP is automatically selected as a position satisfying criterion for minimizing the total tension. In order to validate the suggested algorithm, a motion simulation with the control system in the time domain and a discussion of the results are presented.

• Journal of the Society of Naval Architects of Korea
• /
• v.39 no.1
• /
• pp.28-37
• /
• 2002

In this study nonlinear dynamic behaviors of towed tow-tension cables are numerically analysed. In the case of a taut cable analysis, a bending stiffness term is usually neglected due to its minor effect but it plays an important role in a low-tension cable analysis. A low-tension cable may experience large displacements due to relatively small restoring forces and thus the effects of fluid and geometric non-linearities become predominant. The bending stiffness and non-linearity effects are considered in this work. In order to obtain dynamic behaviors of a towed low-tension cable, three-dimensional nonlinear dynamic equation is described and discretized by employing a finite difference method. An implicit method and Newton-Raphson iteration are adopted for the time integration and nonlinear solutions. For the calculation of huge size of matrices. block tri-diagonal matrix method is applied, which is much faster than the well-known Gauss-Jordan method in two point boundary value problems. Some case studies are carried out and the results of numerical simulations are compared with those of a in-house program of WHOI Cable with good agreements.

• 한국공간정보시스템학회:학술대회논문집
• /
• 2004.05a
• /
• pp.113-122
• /
• 2004

Cable domes deform very largely because of the characteristics of flexible hybrid system and pre-tension, and include geometrical non-linearity in those structural behavior. Especially wind load is more dominant than seismic load, because cable domes are flexible structures whose bending stiffness is very small and self-weight is very light. Therefore, in this paper, the Modified Stiffly Stable Method is applied to analyze the nonlinear dynamic behavior of cable domes and compared these results with ones of the $Newmark-{\beta}$ Method which is generally used. The Seoul Olympic Gymnastic Arena is taken as an numerical example and three kinds of models with giving each different intensity of pre-tension are selected. And dynamic nonlinear behavior of cable domes are analyzed by artificial spectrum of wind velocity wave which is similar to actual wind loads.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.11a
• /
• pp.193-197
• /
• 2004

A finite element analysis is proposed to assess the dynamic response due to impulse excitation of UUV cable system. 'Onnuri'. a special purpose ship of KORDI. was adopted as a support vessel. and all the main dimensions and properties used in the analysis were determined by the support vessel. Transient dynamic response analysis was carried out for various types of impulses. and the magnitude of cable tension induced by impulse was discussed as results.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.4
• /
• pp.73-81
• /
• 1987

Dynamic analysis of tethers and platforms of tension leg platforms(TLP's) subjected to wave forces is presented in this paper. The efficient platform analysis model which can adequately include the dynamic characteristics of tethers is proposed, and the platform motion analyses are mainly carried out using this model. Also, the tether analyses are performed utilizing the finite element method with geometric stiffnesses due to the pre-tension in tethers. Two different. TLP's located in 1000 ft and 3000 ft waters are chosen as example structures. For the purpose of comparison, analyses are also carried out by two different models. One is the conventional model in which the tethers are idealized as weightless springs. The other is the coupled model of platform and tethers. A comparison has been made between the results obtained by three different models mentioned above. Also, effects of the conventional stiffnesses of tethers and the wave exciting forces acting on tethers for the tether responses are examined.

• Journal of The Korean Society of Integrative Medicine
• /
• v.10 no.4
• /
• pp.23-34
• /
• 2022

Purpose : This study examined the effects of pain, neck dysfunction, psychosocial level, headache impact test (HIT), postural alignment, and trapezius muscle tone of the complex exercise program using dynamic taping in patients with tension headache and chronic neck pain with forward head posture. Methods : The design of this is a randomized controlled trial (RCT). Thirty-four patients with chronic neck pain were screened using a randomized assignment program and assigned to experimental group (n=17) and control group (n=17). Both groups underwent a complex exercise program. In addition, the experimental group dynamic taping was applied to the upper trapezius muscle. All interventions were applied three times per week for four weeks. The visual analogue scale (VAS), the neck disability index (NDI), short form-12 health survey questionnaire (SF-12), Headache impact test-6 (HIT-6), Craniovertebral angle (CVA), Cranial rotation angle (CRA), upper trapezius muscle tone were compared to evaluate the effect on intervention. Results : Both groups showed significant differences before and after the intervention in VAS, NDI, SF-12, HIT-6, and CVA, CRA (p<.05). In addition, significant differences in NDI and upper trapezius muscle tone were observed between the experimental group and control group (p<.05). Conclusion : A complex exercise program using dynamic taping for patients with tension headache and chronic neck pain with forward head posture are effective method with clinical significance in improving the function and reducing upper trapezius muscle tone.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.6
• /
• pp.109-120
• /
• 1996

Serpentine belt drive system offers the advantages of light weigh, low cost, quientness, and efficiency. Since these belts are typically longer than conventional belts, a tensioner component is added to maintain acceptable belt tension levels and make no slippage between pulleys and belts. This paper addresses the modeling and analysis of the automotive belt drive systems and also addresses the predicton of slippage on rotational modes. Vibration characteristics are determined from the eigenvalue problem governing the free response. Under certain engine operating conditions, the dynamic tension fluctuations may be sufficient to cause the belt to slip on particular accessory pulleys, It is found that this slippage can be reduced by adding the tensioner component from the analysis of belt tension and belt compression.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.163-168
• /
• 2006

In a micro-unit of electronic-machine, vibration can be excited by a small impact, and this vibration acts as a fatigue load. To measure the vibration effect on the micro unit, a micro dynamic tester is needed to test a micro specimen. In this paper, it has confirmed a movement of the PZT(piezo actuator) to use a sine signal. And, it has confirmed a fracture of specimens by using a tension-tension input signal in PZT. A metal-material property in the micro scale has been tested to compare with the macro scale. A fatigue test has been conducted by using PZT actuator to give a bending-tension effect.