• Computational Structural Engineering
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• v.11 no.1
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• pp.153-160
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• 1998

A small break loss of coolant accident is postulated as a pressurized thermal shock accident in this study. From the temperature and pressure histories of coolant, distributions of the temperature and stress in a vessel wall are analytically calculated. The stress intensity factor and fracture toughness of the vessel wall are determined at the crack tip using the ASME code method and they are compared to check if cracking is expected to occur during the transient postulated. The maximum allowable reference nil-ductility transition temperatures are determined for various crack sizes and the results are discussed.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.1
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• pp.111-116
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• 2001

A practical scheme to reduce failure of the PCB(Printed Circuit Board) of a monitor is introduced using deformed mode shape under mechanical shock. When the monitor is given critical shock loads, cracks are commonly initiated at the tip of a hole on the PCB. Accordingly, a deformed mode shape of the PCB is obtained using a FEM code to define a weak point on the PCB under mechanical shock, and then the position and direction of the hole is determined to prevent the failure at the critical mode shape. Also, the stress intensity factor around the weak point on the PCB is calculated to check the possibility of fracture by normal tensile stress. In conclusion, present research is useful to assist the practical design of components-layout on the PCB.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.6
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• pp.91-98
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• 1992

In the research on the fracture time of soda lime silicate glass under thermal shock, it is shown that the theoretical and experimental fracture times are in good agreement, the suggested method to measure critical stress intensity factor for small three-point bending specimen is useful and the edge temperature before thermal shock on cracked side vs. crack length and fracture time are inversely proportional.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.76-81
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• 2000

Analysis on failure of the panel glass under mechanical shock is the main topic of this study. Since the glass for the LCD panel is thin, it needs to be designed to have enough toughness against mechanical shock. In this paper, a process of estimating fracture of the panel glass is proposed to guarantee reliability of the product. The fracture toughness of the panel glass is used as a criterion of the fracture based on an experimental approach. The stress intensity factor was calculated considering a model with the largest initial crack size on a cut surface and with the boundary force obtained from a dynamic finite element analysis. Critical surface roughness on the cut surface of a typical glass panel, to prevent fracture in case of bending mode, is obtained.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.461-466
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• 2014

The advantages and disadvantages of the various models of crushed ESWL (Extracorporeal Shock Wave Lithotripsy) and their various side effects due to pre-treatment have been reported. We look for the appropriate intensity of the shock wave in the electromagnetic ESWL treatment of patients with lower Inferior Ureter Stones and measure the total running time of C-arm saw. This study is based on the January-June 2014 launch of 65 patients of C university hospital located in Gyeongbuk, who conducted ESWL without pre-treatment. Patients are composed of 48 male and 17 female which were more common in men, while the most common age is 50s. The occurrence of lower urinary tract stones were left and they were more absent than 5mm in size in 39 of the most common. Optimal intensity is one of the suitable intensity of pain, and it is possible to switch the strength of impact to C if one appeals pain. In addition, the C-arm of the total operating time showed $241.73{\pm}30.37$ seconds, which is the size of the lower urinary tract that showed a significant difference (p <0.05). Therefore, ESWL treatment without pre-enforce treatment, the standard for the impact frequency and impact strength depending on the site of ureteral stones is required. The standard for total operating time of C-arm generated for ureteral stones is needed in order to reduce radiation exposure, and the standard for the total operating time for the criteria is needed depending on the site in order to minimize the exposure.

• Advances in aircraft and spacecraft science
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• v.2 no.1
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• pp.45-56
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• 2015

The attitude aerodynamic control is an important subject in the design of an aerospace plane. Usually, at high altitudes, this control is fulfilled by thrusters so that the implementation of an aerodynamic control of the vehicle has the advantage of reducing the amount of thrusters fuel to be loaded on board. In the present paper, the efficiency of a wing-flap has been evaluated considering a NACA 0010 airfoil with a trailing edge flap of length equal to 35% of the chord. Computational tests have been carried out in hypersonic, rarefied flow by a direct simulation Monte Carlo code at the altitudes of 65 and 85 km, in the range of angle of attack 0-40 deg. and with flap deflection equal to 0, 15 and 30 deg.. Effects of the flap deflection have been quantified by the variations of the aerodynamic force and of the longitudinal moment. The shock wave-boundary layer interaction and the shock wave-shock wave interaction have been also considered. A possible interaction of the leading edge shock wave and of the shock wave arising from the vertex of the convex corner, produced on the lower surface of the airfoil when the flap is deflected, generates a shock wave whose intensity is stronger than those of the two interacting shock waves. This produces a consistent increment of pressure and heat flux on the lower surface of the flap, where a thermal protection system is required.

• Korean journal of applied entomology
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• v.15 no.3 s.28
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• pp.153-159
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• 1976

Present paper was attempted to investigate the effects of the light on the sclerotium formation of some isolates of Sclerotinia sclerotiorum(Lib.) do Bary from lettuce, cucumber and rape. The investigations were performed in the both aspects inducing sclerotial primordia from the mycelial colony and developing such primordia. The cultures were grown on potato-dextrose agar and were treated with day-light fluorescent lamps. In the continuous light illumination for 21 days, numbers of sclerotial primordia and matured sclerotia were increased with increasing the light intensity up to about 500 Lux, but on the contrary the dry-weight of matured sclerotia was decreased. In the 800 Lux illumination, induction of the primordia was extremely depressed, and then matured sclerotia were almost not produced. Short-time illumination for 48 hours, although the light intensity was as high as 5000 Lux, increased the numbers of sclerotial primordia and matured sclerotia. Dry-weight of matured sclerotia, however, was slightly increased only at low intensity of 160 Lux. On the other hand, the light shock which u·as alternatively on-of light every one minute for 48 hours increased the number and dry-weight of sclerotia produced, but the former was more effective at 500 Lux shock and the later more effective at 160 Lux shock.

• Laser Solutions
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• v.12 no.4
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• pp.17-25
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• 2009

The surface cleaning method based on the laser-induced breakdown (LIB) of gas and subsequent plasma and shock wave generation can remove small particles from solid surfaces. In the laser shock cleaning (LSC) process, a high-power laser pulse induces optical breakdown of the ambient gas above the solid surface covered with contaminant particles. The subsequently created shock wave followed by a high-speed flow stream detaches the particles. In this work, a novel surface cleaning process using laser-induced breakdown of liquid is introduced and demonstrated. LIB of a micro liquid jet increases the shock wave intensity and thus removes smaller particle than the conventional LSC method. Experiments demonstrate that the cleaning force and cleaning efficiency are also increased significantly by this method.

• The Korean Journal of Ceramics
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• v.4 no.4
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• pp.345-351
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• 1998

Thermal shock resistance of $Al_2O_3$- and Fe-$Al_2TiO_5$-based Castable Refractories was studied using a central heating technique. Ring type specimens, 10mm thick and 20 and 100mm inner and outer diameters, respectively, were rapidly heated on the internal surface of the centre hole using a high power electrical heating element. The temperature field was measured experimentally and modelled using finite element analysis (FEA). The thermal stress field was also modelled using FEA. A radial notch was introduced to the ring specimens to enable calculation of the thermal stress intensity factors (SIF). A special LVDT device was incorporated in the thermal shock tester to monitor crack mouth opening displacement (COD). The thermal shock fracture initiation and crack propagation behaviour of the castable refractories were ascertained using the COD measurements and the fracture mechanics analysis data.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.6
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• pp.1171-1177
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• 2011

A high power laser beam focused on a small area accelerates a thin material that flies and hits other target material in which a shock wave may be induced. This laser induced shock experimental method is more repeatable and cheaper but worse than other experimental method using gas gun or other apparatus. An optical system including a phase zone plate reduces the interference and also makes the focused-beam-intensity distribution uniform. We wrote a computer code that calculates light ray traces. Using the code we designed and fabricated an optical system including a phase zone plate and improved the laser-beam uniformity. We introduce preliminary experimental results of laser induced shock of the samples such as aluminum and other materials.