• The International Journal of Costume Culture
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• v.4 no.3
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• pp.241-248
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• 2001

Re water resistance of shell fabrics intended for we in outdoor apparel was measured using three different standard test methods, ASTM D 751, hydrostatic resistance, procedure A(Mullen test -- with and without a fabric support) and Procedure B (Hydrostatic head test). A database of information on their water resistance performance was created. The data collected with different methods were correlated and the advantages and disadvantages of each method were compared. The Mullen test with a support appears to give higher and more favorable water resistance values on shell fabrics preventing fabric rupture during the test. The hydrostatic head test gave lower hydrostatic pressure values than those measured on the two Mullen tests. The Mullen test is recommended for testing the water resistance of fabrics that high a relatively high water resistance because the Mullen tester applies a wide range of pressure. The hydrostatic head test is recommended for testing the fabrics that have relatively low water resistance. The area of the fabric sample that is in contact with the water is smaller in the Mullen test, so higher pressure levels can be reached and more samples should probably be tested to get a representative value for each fabric types. Furthermore, the hydrostatic head test was deemed more repeatable than the Mullen tests in his study.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.1
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• pp.19-24
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• 2012

This paper presents the results of finite element analysis for the effects of hydrostatic test and operating condition on the weld residual stress at dissimilar metal weld of a pressurizer safety nozzle in a nuclear power plant. For the study, the weld residual stress at ambient condition was analyzed using ABAQUS in the first place. After the weld residual stress analysis, the hydrostatic test condition and operating condition was applied to the same model one after another. The weld residual stress was observed to change due to the successive hydrostatic test and operating condition. The axial residual stresses on inner surface of the dissimilar metal weld and HAZ region were decreased by hydrostatic test and operating condition, which gives beneficial effect on preventing primary water stress corrosion cracking.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.2
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• pp.144-153
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• 2016

This paper aims to demonstrate the design, structure analysis, and hydrostatic pressure test of the cylinder used in 2000m water depth. The cylinder was designed in accordance with ASME pressure vessel design rule. The 1.5 times safety factor required by the general rule was applied to the design of the cylinder, because ASME rule is so excessive that it is not proper to apply to the hydrostatic pressure test. The finite element analysis was conducted for the cylinder. The cylinder was produced according to the design. The hydrostatic pressure test was conducted at the hyperbaric chamber in KRISO. The results of finite element analysis(FEM) and those of the hydrostatic pressure test were almost the same, which showed that the design was exact and reliable.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.645-649
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• 1997

In case of swash plate type axial piston hydraulic motor, hydrostatic bearing used to achieve the lubrication effect on the mechanical sliding contact areas between the following parirs ; sliooer-pad and swash plate,piston and cylinder bore,valve plate and cylinder block, etc. This study discussed the basic charateristic for the hydrostatic slipper-pad bearings with the capillary or orifice restrictor under static load condition. And, we also development of hydrostatic bearing tester for hydrostatic balancing test of pistion & slipper-pad assembly, and some experimental data on supply pressure step responce are reported.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1390-1393
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• 2003

Work factor approach is conveniently used in metal fracture mechanics to determine fracture toughness from a single fracture test. In this work, we investigated the applicability of the work factor approach in order to determine fracture toughness of thick graphite/epoxy composites in the hydrostatic pressure environment from a single fracture test. The effect of hydrostatic pressure on the elastic work factor was studied, The stacking sequence used was multi-directional, [0$^{\circ}$/${\pm}$45$^{\circ}$/90$^{\circ}$]. The hydrostatic pressures applied were 0.1 MPa, 100 MPa, 200 MPa, and 300 MPa. The results showed that the elastic work factor was not affected by the hydrostatic pressure, The elastic work factor decreased in a linear fashion with crack length.

• The KSFM Journal of Fluid Machinery
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• v.19 no.5
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• pp.35-41
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• 2016

This paper deals with the design, manufacturing and test evaluation of a hydrostatic bearing applied to a hydraulic model turbine. The design parameters of a hydrostatic bearing, considering machining and assembly tolerances, and recommended values of design parameters are presented. Also the simple design procedure of a hydrostatic bearing by utilizing the reference results is proposed. In order to illustrate the utility and validity of the proposed design procedure, two hydrostatic bearings are manufactured and test evaluation of these bearings are performed. In results, the proposed design procedure can be utilized as an effective tool at the initial design screen of a hydrostatic bearing. However, the 2D bearing governing equation should be solved to obtain the optimal design of a hydrostatic bearing.

• Journal of Applied Reliability
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• v.12 no.3
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• pp.165-176
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• 2012

Hydrostatic bearing improves performance and life time of a product by avoiding solid friction and reducing viscosity friction with the help of creating pressure equilibrium between two faces doing relative motion. This study suggests failure analysis and test evaluation for a ball joint that adopts the hydrostatic bearing and introduces the entire process to improve reliability of the product by design improvement. A typical failure is growth of friction torque by solid friction, and its failure cause is determined and the improvement is proposed. Finally, reliability improvement is established by analysis of the results of before and after acceleration test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.769-773
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• 2001

Linear hydrostatic bearings have high stiffness, high damping and excellent guided motion straightness, and thus they are suitable for high precision machine tools. This paper describes the procedure for design and test of a high precision stamping press with vertical hydrostatic bearings. For a hydrostatic bearing set designed and manufactured, measurements were made for the straightness, repeatability and stiffness. They are found to be 1.36$\mu\textrm{m}$/100mm, 0.19$\mu\textrm{m}$/100mm and 1, 261N/$\mu\textrm{m}$ respectively. Based upon the experiences with the hydrostatic bearing, an improved design of the precision press is proposed.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.4
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• pp.287-292
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• 2011

To evaluate the pressure-resistant performance of underwater equipment, hyperbaric chamber test facility which can make the hydrostatic pressure is used. In this test, strain gage is generally applied to measure the strain of object under test is suitable for measuring a tiny deformation, but it can not measure a large deformation. Thus this paper suggests a method to estimate the over -order deformation of object under test by the image processing with the image acquired from underwater camera in the hydrostatic test. The main procedure of suggested method comprises the first step to find significant points by processing the image two dimensionally and the second step to estimate a deformation of object under test by tracking the motion of these points. If completing the remained research which is estimating the deformation and comparing it with a real one, it can be a method to measure the over -order deformation of object under test.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.6
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• pp.711-729
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• 2018

This paper reports on the experimental investigations on the failure modes of ring-stiffened cylinder models subjected to external hydrostatic pressure. Nine models were welded from general structural steel. The shells were initially formed by cold-rolling, and flat-bar ring frames were welded to the shell. The hydrostatic pressure tests were conducted by using water as the medium in pressure chambers. The details of the preparation and main test were briefly explained. The investigation identified the consequence of the structural failure modes, including: shell yielding, local shell buckling between ring stiffeners, overall buckling of the shell together with the stiffeners, and interactive buckling mode combining local and overall buckling. In addition, the ultimate strengths were predicted by using existing design codes. Non-linear numerical computations were also conducted by employing the actual imperfection coordinates. Finally, accuracy and reliability of the predictions of design formulae and numerical were substantiated with the test results.