• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.2
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• pp.7-13
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• 2012

A spacer grid which is one of the most important structural components in a pressurized water reactor fuel is an interconnected array of slotted grid straps, welded at the intersections to form an egg-crate structure. The spacer grid is required to not only protect fuel rods stably but also have sufficient lateral crush strength for the sake of enabling shut-down of the nuclear reactor during abnormal operating environments. Then, the lateral crush strength of the spacer grid is closely related with welding quality of the spacer grid. Previous research on the crush strength analysis of the spacer grid had been performed using only parent material properties. In this study, to investigate the effect on the crush strength of the spacer grid when used mechanical properties in weld zone instead of parent material properties, crush strength analysis considering mechanical properties in weld zone obtained from the instrumented indentation technique was performed and compared the results with the previous research.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1663-1668
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• 2012

A spacer grid, which is one of the structural components in a PWR fuel, is an interconnected array of slotted grid straps that are welded at the intersections to form an egg-crate structure. The spacer grid is required to have sufficient lateral crush strength to enable nuclear reactor shut-down during abnormal operating environments. Previous studies on the lateral crush strength analysis of the spacer grid were performed using only the base material properties. In this study, to investigate the effect of the lateral crush strength of the spacer grid when using the mechanical properties in the weld zone instead of the base material properties, lateral crush strength analysis by considering the mechanical properties in the weld zone as obtained from the instrumented indentation technique was performed, and the results were compared with those of previous studies.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1581-1586
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• 2009

The CEM (Crash Energy Management) concept is getting important in rail vehicle design to minimize Injury on passengers and drivers on crash event. In this paper, the accuracy of the FEA analysis result was verified through the crush test on the front part of a non-CEM based carbody. Using the verified FEA analysis method, the energy absorbing capability of the CEM based carbody was estimated.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.128-136
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• 2003

In today's design trend of vehicle structure, crush zone is fiequently reinforced by adding a box-shaped sub-frame in order to avoid an excessive deformation against a high-speed offset barrier such as EU Directive 96/97 EC, IIHS offset test. That kind of vehicle structure design results in a relatively monotonic crash pulse for airbag ECU(Electronic Control Unit) located at non-crush zone. As for an angular crash event, the measured crash signal using a single-axis accelerometer in a longitudinal direction is usually weaker than that of frontal barrier crash. Therefore, it is not so easy task to achieve a satisfactory crash discrimination performance for offset and angular crash events. In this paper, we introduce a new crash discrimination algorithm using an electronic X-Y 2-axis accelerometer in order to improve crash discrimination performance especially for those crash events. The proposed method uses a crash signal in lateral direction(Y-axis) as well as in longitudinal direction(X-axis). A crash severity measure obtained from Y-axis acceleration is used to improve the discrimination between fire and no-fire events. The result obtained by the proposed measure is logically ORed with an existing algorithm block using X-axis crash signal. Simulation and pulse injection test have been conducted to verify the performance of proposed algorithm by using real crash data of a 2,000cc passenger vehicle.

• Archives of Reconstructive Microsurgery
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• v.15 no.1
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• pp.10-16
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• 2006

We retrospectively evaluated our results of replantations of distal digital amputations and analyzed the factors deterrent to the survival of replanted digits. From January 2004 to 2005 June, we performed 101 cases of replantations following complete amputations at or distal to interphalangeal joint level. The study included 98 patients with a mean age of 35.6 years (range 1 to 63 years). Amputation level correlated to zone I (distal to the lunula)in 47 cases and zone II (lunula to distal interphalangeal joint) in 54 cases according to Yamano's classification. According to the mechanism of amputation, 24 cases (22.9%) suffered from guillotine type injury, 27 cases (27.1 %) from avulsion type injury and 50 cases (50%) from crush type injury. In all cases, a single arterial anastomosis was performed. Venous anastomosis on either volar or dorsal side was performed in 12 cases of amputation in zone II. Salvage procedure for venous drainage was performed in 98 cases. The mean duration of salvage procedures was 5.9 days (ranging from 4 to 14 days). Successful replantation was achieved in 96 cases (95.1%), which included 93.7% cases in zone I amputations and 96.3% cases in zone II amputations. A single venous anastomosis was performed in 12 cases of amputation in zone II. All of them survived completely. Among the 5 cases that failed to survive, 3 cases were related with avulsion injury in zone I. Initial mechanism of injury determines the survival rate of amputated parts as it is directly related with the status of vessels and soft tissues. Meticulous precaution during the salvage procedure may affect the overall survival rate of distal digital replantations.

• Journal of the Korean earth science society
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• v.22 no.6
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• pp.548-557
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• 2001

Ultramafic rocks in the Yesan talc ore deposits area are unknown age plutonic rocks which intruded PreCambrian Yoogoo gneiss, and were intruded by Jurassic biotite granite, and Cretaceous acidic and mafic dykes. The ultramafic rocks consist mainly of serpentinite with some amphibolite and talc ore body. The serpentinites are divided 5 rock types (S1${\sim}$S5) on the basis of the developed degree of serpentine phenocrysts and layerings. It seems that the original rocks of the serpentinites were co-magmatic peridotites (dunite and pyroxene peridotite). Main serpentinization from the original rocks was occurred during amphibolite facies regional metamorphism in Choongnam area which Yoogoo gneiss was affected. Main steatitization from the serpentinites was hydrothermal alteration by ascended hydrothermal fluid through crush zones.

• Journal of the Korean Society for Railway
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• v.2 no.1
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• pp.16-27
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• 1999

The purpose of this study is to suggest the effective analytical procedure using finite element model for the crashworthiness of motorized trailer of high speed train. The static crush of rectangular section frame is analyzed by experiment and numerical simulation. The equivalent thickness distribution of the aluminum frame ensuring the same energy absorption as the steel frame is obtained. In the analysis of end-on collision of TGV-K, deformed pattern and section forces are obtained, and the effect of crushable zone are examined. The numerical results are applied to the design of motorized trailer of Korean high speed train.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2040-2045
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• 2008

The priority of Crashworthiness concept for rolling stock is progressively increasing to reduce the damage of drivers and passengers as well as the car. For the first step of this research, the analysis of the crash elements have been performed. Also the longitudinal collapse force and mode is important point for whole carbody structure to guarantee the lower force at end part rather than the main passenger area. The carbody quasi-static collapse analysis and real test has been performed in the research. The crash elements FEA and test has been performed as well. After the initial Analysis and test, the correlation analysis between the FEA and test has been performed by FEA tunning. All this result will be used for real crashworthiness design for carbody structure.

• Journal of Energy Engineering
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• v.14 no.2 s.42
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• pp.153-158
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• 2005

In order to investigate the short-term performance of polyethylene electrofusion joints, the mechanical tests and stress analysis have been conducted to the artificially defected weld joints. The defects of lack of fusion with a square-type were fabricated with 10, 20, 30, 40, 50, 60$\%$ size of the width of heat-ing wire zone, respectively. In this defect sires range, both tensile and bending test results showed the dependence of defect size to the electrofusion joints performance, but both sustained pressure and crush test results didn't. The numerical stress analysis results including the soil and internal pressures, tensile and bend-ing stresses clearly showed the dependence of fusion defect size. Based on both mechanical test and stress analysis results, the maximum acceptable defect size in polyethylene electrofusion joints is discussed.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.508-522
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• 2019

Because of the slope failure, not only property damage but also human damage can occur, slope stability analysis should be conducted to predict and reinforce of the slope. This paper, defines the ground areas that can be characterized in terms of slope failure such as Rockmass jointset, Rockmass fault, Soil, Leakage water and Crush zone in sloped images. As a result, it was shown that the deep learning instance segmentation network can be used to recognize and automatically segment the precise shape of the ground region with different characteristics shown in the image. It showed the possibility of supporting the slope mapping work and automatically calculating the ground characteristics information of slopes necessary for decision making such as slope reinforcement.