• 한국기계연구소 소보
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• s.20
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• pp.49-55
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• 1990

Filament-Wound composite pressure vessels offer significant weight saving over the conventional metal pressure vessels. S-2 glass/epoxy pressure vessel was designed, fabricated and tested. It was considered, in the analysis that the matrix and the metal liner of FRP pressure vessel shared the internal pressure. The thicknesses of hoop and helical layers were determinded by the computer program developed for the design of FRP/Metal structural pressure vessel. The computer program increased the structural efficiency about 14% comparing with the netting analysis. The experimental measurement on the deformation by internal pressure agrees with the theoretical analysis within the accuracy of 5%.

• The Korean Journal of Physiology
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• v.23 no.2
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• pp.225-236
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• 1989

1) At the isolated perfused guinea-pig and rat heart heterometric autoregulation of the myocardium and myogenic autoregulation of the coronary vessels were induced by means of stepwise increases of perfusion pressure. 2) According to this loading test Frank-Starling function curves of the left ventricle and pressure-flow curves of the coronary vessels can be drawn. This graphic evaluation gives more information about the condition of the heart and the coronary vessels than simple evaluation under hemodynamic equilibrium. 3) There are significant differences in both curves between animal species and between different perfusate Mg concentration. 4) Myogenic autoregulation is not affected by the cyclooxygenase inhibitors indometacin and me- clofenamate. Thus it appears unlikely that prostanoides are involved in myogenic autoregulation. 5) Ca antagonists (Gallopamil, prenylamine) depress myogenic autoregulation dose-dependently. Enhanced myogenic autoregulation, induced by low extracellular magnesium, can be reduced effectively by Gallopamil. 6) Ginsenosides from Panax ginseng as well as the ginsenoside 'Rg' are effective inhibitors of myogenic autoregulation without major negative inotropic effects.

• Structural Engineering and Mechanics
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• v.5 no.2
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• pp.193-207
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• 1997

Experimental tests are described on three ring stiffened machined circular cylinders and three ring stiffened machined circular cones, which were tested to destruction under uniform external pressure. All six vessels failed by inelastic general instability. The experiments showed that the vessels initially deformed plastically at mid-bay in the circumferential direction, and this caused the circumferential tangent modulus to become much less than the elastic Young's modulus, causing the vessels to fail through plastic general instability at pressures much less than that predicted by elastic theory. Based on a thinness ratio, two semi-empirical design charts are provided, which are intended to be used for design purposes in conjunction with the finite element method and a plastic reduction factor.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.48-55
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• 2012

Pressure vessels in vehicle industries, power plants, and chemical industries are often affected by flaw and defect generated inside the pressure vessels due to production processes or being used. It is very important to detect such internal defects of pressure vessel because they sometimes bring out serious problems. In this paper, an optical defect detection method using digital shearography is used. This method has advantages that the inspection can be performed at a real time measurement and is less sensitive to environmental noise. Shearography is a laser-based technique for full-field, non-contacting measurement of surface deformation (displacement or strain). The ultimate goal of this paper is to detect flaws in pressure vessels and to measure the lengths of the flaws by using unwrapping, phase images which are only obtained by Phase map. Through this method, we could decrease post-processing (next processing). Real length of a pixel can be calculated by comparing minimum and maximum unwrapping images with shearing angle. Through measuring several specimen defects which have different lengths and depths of defect, it can be possible to interpret quantitatively by calculating gray level.

• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.40-47
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• 1999

A numerical study on gaseous explosion was carried out to predict the transient pressure behavior with the partial rupture in confined vessels. Equations, assumptions and solutions for central ignition of premixed gases in closed spherical vessels are proposed with various equivalence ratios of gas fuel, as $CH_4$ and $C_3H_8$, vent areas and vent opening pressures. Given vent opening pressure in a vessel, the magnitude of second peak pressure results from the vent areas and burning velocity, varied by equivalence ratio of gas fuel. In a living room of an apartment, the higher second peak pressure than the vent pressure is not appeared due to its large window areas. As vent opening pressure is higher, the larger damage by gaseous explosion is expected and the larger vent area is necessary for relieving the damage. In the same concentration, the gaseous explosion by propane rather than methane shows the larger damage due to its higher adiabatic flame temperature and equivalence ratio.

• Journal of Ocean Engineering and Technology
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• v.14 no.1
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• pp.88-94
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• 2000

Recently various pressure vessels like an atomic reactor and plant facilities become more larger and are needed to bear in both very high temperature and pressure condition. And in making such a high pressure vessels the amount of annual usage of 2 $\frac {1}{4}$ Cr-1Mo steels which are predominant to resist high temperature high pressure and corrosive circumstances are increasing. But despite of this advantage of 2 $\frac {1}{4}$Cr-1Mo steel. when PWHT(post welding heat treatment) is carried out lots of reheating cracks are occur. In this reason it is strongly needed to study and examine the mechanical behavior of welded joints through welding to PWHT process. So in this study welded nozzle of pressure vessel where reheat cracks are frequently occur are selected for analysis the crack-occurrence mechanism.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.2
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• pp.20-24
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• 2015

During refueling Outage, In-service inspections(ISIs) for the Nuclear Power Plant components are mandatory requirement in accordance with ASME Code Sec. XI. Especially, in current ultrasonic testing is one of the most important NDT techniques that are used for volumetric examination methods for nuclear power plant components, and accurate sizing of flaw indication by UT is essential to assure the integrity of the components. However, ASME code specifies minimum requirement for vessel examination procedure, and so far many different flaw sizing approaches have been tried to apply. Through the Round Robin Test(RRT), the accuracy of ultrasonic flaw sizing using DAC techniques was measured with the mock-ups simulating typical pressure vessel welds. These mock-ups contain artificially introduced flaws of known size and location. This paper shows experimental comparison data on the accuracy of techniques using such as 6dB drop, 50%DAC, 20%DAC and 20%DAC with beam spread correction, and also shows that diverse DAC techniques can be effectively applied to the assessment of the flaw sizing for pressure vessel welds in the stage of welding and fabrication.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.2
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• pp.1-8
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• 2010

Nuclear steam generator tubes have experienced wear degradation at tube support structure. Morphology of wear scar was analyzed by using eddy current signal. A burst test facility for steam generator tubes was established and tubes with 3 types of defects were tested. The burst test results show that the depth of wear scar is the main factor influencing the burst pressure of tubes, meanwhile, both the longitudinal length and the angle also have effect on the burst pressure. Based on test results, the burst pressure equation for wear degradation was proposed.

• Journal of Welding and Joining
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• v.13 no.2
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• pp.139-149
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• 1995

Many pressure vessels for the power plants are fabricated from low alloy ferritic steels. The inner sides of the pressure vessels are commonly weld_cladded with austenitic stainless steels to minimize problems of corrosive attack. The submerged-arc welding(SAW) process is now used in preference to other processes because of the possibilities open to automation to reduce the overaII welding times. The most reliable way to avoid underclad cracks(UCC) which are often detected at the overlap of the clad beads is to use nonsusceptible steels such as SA508 class 3. At present domestically developed forging steel of SA508 cl.S is now being cladded with single layer by using 90mm wide strip, which transfers higher heat input into the base metal compared to the conventional two layers strip cladding which has been in wide use with 30-60 mm wide strip. But the current indices for the influence of heat input on crack susceptibility are not accurate enough to express the subtle difference in crack susceptibility of the steel. Therefore, the purpose of this present study is: l) To determine UCC susceptibility on domestic forging steel, SA508 cl.S cladded with single layer by using submerged arc 90mm strip and, 2) To optimize heat input range by which the crack susceptibility could be eliminated.

• Composites Research
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• v.14 no.3
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• pp.10-17
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• 2001

A reseach was peformed to develop composite pressure vessels in conjunction with design, fabrication, and test. Fiber pattern and angels were decided by CADFIL software and they were [$liner/15^{\circ}/15^{\circ}/90^{\circ}/18^{\circ}/90^{\circ}/21^{\circ}/21^{\circ}/90^{\circ}$]. Fabrication of bottles were done by 5-axis filament winding machine. During fabrication fiber optic sensors were embedded to measure the strain at points when internal pressure was applied by water pump. Conventional strain gage instrumentation showed the stable test results. The test results were compared to finite element analysis results and they were close each other in strain values. One can see the successful design and fabrication of single boss composite vessels.