• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.225-227
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• 2004

The compressive characteristics of thick carbon/epoxy composite in a submarine environment was investigated in this study. The specimens made of thick carbon fiber/epoxy composite that were immersed into seawater Jar thirteen months. the seawater content at saturation was about $1.2\%$ of the specimen weight. Compressive tests have been performed in different hydrostatic pressures of 0.1 MPa, 100 MPa, 200 MPa, and 270 MPa. The results showed that the compressive elastic modulus increased about $12.3\%$ as the hydrostatic pressure increased from 0.1 MPa to 200 MPa. The results also showed that compressive fracture strength increased $28\%$ and compressive fracture strain increased $8.5\%$ as the hydrostatic pressure increased from 0.1 MPa to 270 MPa.

• Journal of Drive and Control
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• v.17 no.4
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• pp.113-124
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• 2020

Most of the work of construction equipment and agricultural machinery is done in off-road conditions. Autonomous driving required in these conditions uses GPS sensors, and PID controllers to control their speed and position. The hydrostatic steering, which is composed of a PSU, hydraulic hoses, and cylinders, rather than a mechanical coupling is used in these equipments. The PSU plays a key role in hydrostatic steering. Precise control of the position under various conditions requires detailed behavioral analysis of the basic components and operation. Two Gerotor PSU is now a commonly used safer option. The components of the PSU can be divided into mechanical and hydraulic actuating elements by its behavior. Since the system is combined by mechanical and hydraulic elements, the modelings are performed using Amesim, which is one of the most effective for the multi-domain dynamic system analysis. To confirm the validity of the model, input torque and pressures are checked with varying steering speed. The opening and the steering speed of normal and newly designed control valve set is investigated with the effect of centering spring force and friction. Finally, simulation results with fully detailed model with two gerotors are analyzed and compared with simple model.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.571-586
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• 2021

The present paper studies the influence of the inhomogeneous initial stresses in the bi-layered hollow cylinder and it is assumed that these stresses are caused by the hydrostatic pressures acting on the interior and outer free surfaces of the cylinder. The study is made by utilizing the version of the three-dimensional linearized theory of elastic waves in bodies with initial stresses for which the initial stress-strain state in bodies is determined within the scope of the classical linear theory of elasticity. For the solution to the corresponding eigenvalue problem, the discrete-analytical method is employed. Numerical results are presented and analyzed for concrete selected pairs of materials. According to these results and their analyses, it is established that, unlike homogeneous initial stresses, the influence of the inhomogeneous initial stresses on the torsional wave dispersion has not only quantitative but also qualitative character. For instance, in particular, it is established that as a result of the initial stresses caused by the hydrostatic pressure acting in the interior free surface of the cylinder, the cut-off frequency appears for the fundamental dispersive mode and the values of this frequency increase with the intensity of this pressure.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.4
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• pp.191-195
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• 2004

This study investigated the effect of deep-sea environment on the compressive characteristics of polymer matrix composite. The specimens used in the experiment were thick Carbon-Epoxy composites that were made from Carbon-Epoxy prepregs. The specimens were immersed into seawater for thirteen months. The seawater content at saturation was about 1.2% of the specimen weight. The hydrostatic pressures applied were 0.1 MPa, 100 MPa, 200 MPa, and 270 MPa. It was found that the compressive elastic modulus increased about 10% as the hydrostatic pressure increased from 0.1 MPa to 200 MPa. The modulus increased additional 2.3％ as the pressure increased to 270 MPa. It was also found that compressive fracture strength and compressive fracture strain increased with pressure in a linear behavior. Compressive fracture strength increased 28％ and compressive fracture strain increased 8.5％ as the hydrostatic pressure increased from 0.1 MPa to 270 MPa.

• Advances in concrete construction
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• v.9 no.5
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• pp.503-510
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• 2020

Concrete dams are important structures due to retaining amount of water on their reservoir. So such kind of structures have to be designed against static and dynamic loads. Especially considering on critical importance against blasting threats and environmental safety, dams have to be examined according to the blast loads. This paper aims to investigate structural response of concrete gravity dams under blast loads. For the purpose Sarıyar Concrete Gravity Dam in Turkey is selected for numerical application with its 85 m of reservoir height (H), 255 m of reservoir length (3H), 72 m of bottom and 7 m of top widths. In the study, firstly 3D finite element model of the dam is constituted using ANSYS Workbench software considering dam-reservoir-foundation interaction and a hydrostatic analysis is performed without blast loads. Then, nearly 13 tons TNT explosive are considered 20 m away from downstream of the dam and this is modeled using ANSYS AUTODYN software. After that explicit analyses are performed through 40 milliseconds. Lastly peak pressures obtained from analyses are compared to empirical equations in the literature and UFC 3-340-02 standard which provide unified facilities criteria for structures to resist the effects of accidental explosions. Also analyses' results such as displacements, stresses and strains obtained from both hydrostatic and blasting analysis models are compared to each other. It is highlighted from the study that blasting analysis model has more effective than the only hydrostatic analysis model. So it is highlighted from the study that the design of dams should be included the blast loads.

• Food Science and Biotechnology
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• v.16 no.1
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• pp.49-54
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• 2007

The effects of hydrostatic pressure (HP) treatment on the physicochemical, morphological, and textural properties of bovine semitendinosus (ST) muscle were assessed. Based on SDS-PAGE, the decrease in HP-treated ST muscle protein solubility in 0.1 M KCl buffer (pH 7.0) was attributable to a reduction in the levels of sarcoplasmic protein, and the protein solubility decrease observed in 0.6 M KCl buffer (PH 7.0) was attributable to a reduction in the levels of myosin heavy-chain and actin. Scanning electron microscope (SEM) observations showed that muscle fibers became finer and more compact with increasing pressures. The shear force and hardness of ST muscle pressurized to 300 MPa decreased significantly (p<0.05), however samples pressurized at 100 and 500 MPa exhibited a significant increase in both attributes relative to the control sample (p<0.05).

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.377-380
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• 2000

The collapsible phenomena of the circular tubes due to the excessive transmural pressure are investigated experimentally. Collapsible tubes are installed in the test section where the external pressure is applied to the test tubes by applying the hydrostatic head. The collapsible circular tubes are made of rubber, whose diameters are 6 and 4.2 mm, respectively. The hydrostatic water head of the upper reservoir is applied to the test section. Pressures at the upstream and downstream sides are measured by the pressure transducers. The collapsible phenomena are observed as the transmural pressure Increases, and also the flutter phenomenon occurs due to the critical transmural pressure.

• Structural Engineering and Mechanics
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• v.9 no.1
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• pp.51-68
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• 2000

The paper presents theoretical and experimental investigations on three varying thickness circular cylinders, which were tested to destruction under external hydrostatic pressure. The five buckling theories that were presented were based on inelastic shell instability. Three of these inelastic buckling theories adopted the finite element method and the other two theories were based on a modified version of the much simpler von Mises theory. Comparison between experiment and theory showed that one of the inelastic buckling theories that was based on the von Mises buckling pressure gave very good results while the two finite element solutions, obtained by dividing the theoretical elastic instability pressures by experimentally determined plastic knockdown factors gave poor results. The third finite element solution which was based on material and geometrical non-linearity gave excellent results. Electrical resistance strain gauges were used to monitor the collapse mechanisms and these revealed that collapse occurred in the regions of the highest values of hoop stress, where considerable deformation took place.

• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.15-21
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• 1990

This study focuses the mechanical deformation response predicted by the plasticity model for polycrystalline ice. To describe various deformation characteristics, ice is idealized as a perfectly plastic material using an asymptotic exponential failure criterion. This criterion is suite for describing materials which exhibit brittle deformation at low hydrostatic pressure and ductile deformation at high hydrostatic pressure. The results are compared to those of continuum damage mechanics model. Plasticity model shows good agreement with damage model and experimental results for high confining pressures even at high strain-rates which is usually considered as a brittle condition under uniaxial compression.

• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.165-165
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• 1990

This study focuses the mechanical deformation response predicted by the plasticity model for polycrystalline ice. To describe various deformation characteristics, ice is idealized as a perfectly plastic material using an asymptotic exponential failure criterion. This criterion is suite for describing materials which exhibit brittle deformation at low hydrostatic pressure and ductile deformation at high hydrostatic pressure. The results are compared to those of continuum damage mechanics model. Plasticity model shows good agreement with damage model and experimental results for high confining pressures even at high strain-rates which is usually considered as a brittle condition under uniaxial compression.