• Journal of Trauma and Injury
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• v.25 no.4
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• pp.166-171
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• 2012

Purpose: In patients with traumatic hemoperitoneum or pelvic bone fracture who underwent angiography and embolization, we want to find the prognostic factors related with mortality. Methods: Patients(333 patients) who visited our hospital with traumatic injury from March 2008 to April 2012 were included in this study. Only 37 patients with traumatic hemoperitoneum or pelvic bone fracture underwent angiography and embolization. A retrospective review was conducted, and Glasgow coma scale (GCS), Revised trauma score (RTS), Injury severity score (ISS), initial laboratory finding and time interval, the amount of transfusion from the arrival at the ER to the start of embolization, and the vital signs before and after procedure were checked. Stastical analysis was conducted using the Chi square and Mann-Whitney U test. Results: In univariate analysis, the amount of transfusion, the base deficit before procedure, the systolic blood pressure before and after the procedure, the GCS, the RTS and the ISS were significantly associated with prognosis. In the multivariate analysis, the ISS and the base deficit had significant association with prognosis. Of the 37 patients who underwent angiography and embolization, 31 patients needed not additional procedure (Group A) while the other 6 patients needed an additional procedure (Group B). After procedure, a statistically significant higher blood pressure was observed in Group A than in Group B. As to the difference in blood pressure before and after the procedure, a statistically significant decrease in systolic blood pressure was observed in Group B, but an increase was observed in Group A. Conclusion: In traumatic hemoperitoneum or pelvic bone fracture patients who underwent angiography and embolization, GCS, ISS, RTS, transfusion amount before the procedure, initial base deficit and systolic blood pressure were factors related to mortality. When patients who underwent angiography and embolization only were compared with patients who underwent re-embolization or additional procedure after the first embolization, an increase in systolic blood pressure after embolization was a prognostic factor for successful control of bleeding.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.556-561
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• 2006

In this study, the failure of the automotive clutch disk was investigated. During the process of power transmission, clutch disk plates did repeated work of releasing and engaging the pressure plate. The effects of unbalance rotation in the abnormal vibration and torque amplitude under engaged state were measured from this experiment. In order to reduce the unbalance, a modified clutch disk shape was developed. With a three-dimensional model of the stopper pin, to predict fatigue fracture, finite element analysis was carried out and evaluated the improvement of the new clutch disk.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.84-84
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• 2003

The effects of Ti addition on microstructure and mechanical properties of (Al+Xat.%Ti)2at%B (X=0.5, 1, 2) fabricated by mechanical alloying and spark plasma sintering (SPS) were investigated. These alloys were prepared by high energy ball milling (attritor) and then fracture toughness was investigated by using a charpy impact tester. The SPS method was used to consolidate (Al+Xat.%Ti)fat.%B with the pressure of 50MPa. The powders were successfully consolidated to alloy which the theoretical density is 99%. It was confirmed that the fracture toughness of Al-Bat.% matrix composites was increased by the addition of Ti.

• Journal of the Korea Concrete Institute
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• v.12 no.3
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• pp.31-37
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• 2000

When a crack is produced in a concrete structure, a micro crack zone of fracture process zone (FPZ) appears at the crack tip. To investigate the behaviour of this the micro crack zone, nonlinear fracture mechanics (NLFM) must be applied. However, when a massive concrete structure such as a concrete gravity dam is considered, the micro crack zone can be neglected and the structure can be assumed to have linear elastic fracture mechanics (LEFM) behaviour. This study is divided into two main topics : (1) Calculating stress intensity factor (SIF) at the crack tip by surface integral method and (2) Investigating the propagation of the initial crack. If the initial crack propagates, the angle of the propagation is calculated by using maximum circumferential tensile strength theory. This study, also, contains the effects of body forces and water pressures on the crack face.

• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1259-1264
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• 1994

$\beta$-Sialon has been regarded as one of promising materials showing high strength, fracture toughness, corrosion resistence and wear resistence. The improvement of the fracture toughness and tribological properties of $\beta$-Sialon (Z=1) has been attempeted by fabricating the $\beta$-Sialon/ SiC whisker composite. Each of green body composed of following ingredients, i.e., Si3N4, AlN, Y2O3 nd SiC, respectively, was first fired at 178$0^{\circ}C$ for 3hrs in N2 atmosphere and then post-HIPed at 173$0^{\circ}C$ for 1 hr under 170 MPa for N2 gas pressure. The fracture toughness, flexural strength and tribological properties increased with increasing SiC whisker content, despite the reduction of the relative density and hardness. $\beta$-Sialon/15 vol% SiC whisker showed a significant enhancement of wear resistance compared to the monolithic $\beta$-Sialon. The addition of SiC whisker caused the reduction of the density and hardness, but induced the increment of wear resistance.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.157-162
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• 1997

Silicon Nitride samples with different microstructure were prepared by hot pressing and subsequent heat treatment under N2 gas pressure. The fracture toughness (KIC)of Si3N4 increased with the increase of grain size, but the bending strength of plain specimen($\sigma$F) decreased. The relation between fracture stress($\sigma$c) and equivalent crack length(ae) agreed well with the calculated values by process zone size failure criterion. A probabilistic failure assessment curve is proposed based on both statistical character of $\sigma$F and KIC.

• Journal of Ocean Engineering and Technology
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• v.7 no.2
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• pp.91-102
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• 1993

The elastic-plastic fracture thoughness J sub(IC) of Nuclear Reactor Vessel Steel(SA 508-3) which has high toughness was discussed at temperatures RT, $-20^{\circ}C$, $200^{\circ}C$ and 1/2/CT specimen was used for this study. Especially the two methods recommended in ASTM and JSME were compared. It was difficult to find J sub(IC) by ASTM R-curve method with the specimen used for this research, while JSME R-curve method yielded good result. The stretched zone width menthod gave slightly larger J sub(IC) values than those by the R-curve method for SA 508-3 steel.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.65-73
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• 2004

Fatigue crack growth from surface defects is one of the most important subjects for the evaluation and the assurance of safety in pressure vessels, piping systems, LPG/LNG fuel tank and other various structures. This paper attempts to analysis some practical or general problems such as the estimation of crack growth life to penetrate the plate thickness, based on fatigue crack growth a single surface flaw and the interaction of multiple flaws. An experiment on the coalescence of multiple undercuts was carried out under cyclic tension condition as a attempt to the analysis of multiple crack problems. It is noted that the fracture strength is characterized by the analogy to that in a single crack growth.

• Proceedings of the KWS Conference
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• 2003.05a
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• pp.216-218
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• 2003

A fracture mechanics analysis methodology for stress corrosion cracks (SCCs) existing in the Alloy 600 nozzle weld joint for control rod drive mechanisms (CRDMs) of pressurized water reactor is studied. Effects of weld residual stresses on the sub-critical crack behavior during the reactor operation are investigated by a fracture mechanics analysis, which is combined with the finite element alternating method. It is found that effects f the residual stresses on the stress intensity factor (SIF) and crack growth rate (CGR) are dominant and values of SIF and CGR of cracks in the region of weld joint are increased by a factor of three or more on an average.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.127-133
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• 2007

SG-365 steel is an important material and used for manufacturing a pressure vessel which the gas piping. In this investigation, the elastic plastic fracture toughness of this material is evaluated by the unloading compliance method according to the ASTM E813-97 and E1152-97 method on the smooth and side groove 1CT specimens. The effect of smooth and side groove is studied on the elastic plastic fracture toughness. The side grooved specimen is very useful in estimation of the $J_{IC}$. It is much easier than the smooth specimen to the onset of the ductile tearing by the R curve method. Besides, it improves the accuracy of toughness values, decreases a phenomenon of the tunneling and shear lip by the side groove.