• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.6
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• pp.451-458
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• 2005

The effects of fiber orientation on acoustic emission(AE) characteristics have been studied for various composite laminates. Reflection and transmission optical microscopy were used to investigate the damage zone of specimens. AE signals were classified through short time Fourier transform(STFT) as different types: AE signals with a high intensity and high frequency band were due to fiber fracture, while weak AE signals with a low frequency band were due to matrix cracking and/or interfacial cracking. Characteristic feature in the rate of hit-events having high amplitudes showed a procedure of fiber breakages, which expressed the characteristic fracture processes of notched fiber-reinforced plastics with different fiber orientations. As a consequence, the behavior of fracture in the continuous composite laminates could be monitored through nondestructive evaluation(NDE) using the AE technique.

• The Korean Journal of Nuclear Medicine
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• v.32 no.4
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• pp.305-313
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• 1998

The reduction in the amount of asialoglycoprotein (ASGP) receptor, which resides exclusively on the plasma membrane of functioning mammalian hepatocytes, as a consequence of hepato-cellular damage has been demonstrated in various pathologic conditions of the liver. Galac-tosylated human serum albumin (GSA) is a newly developed receptor-binding agent, specific for the ASGP receptor. Tc-99m GSA binds quantitatively to liver ASGP receptors and the rate of accumulation in the liver is dependent on hepatic function represented as the amount of receptor, as well as the amount of ligand injected, its affinity to the receptor and the hepatic blood flow. The findings of Tc-99m GSA scintigraphy were reported to reflect the hepatic function of the patients with large hepatic tumors, obstructive jaundice, acute and chronic liver disease. Tc-99m GSA scintigraphy is an easy and reliable test and has the clinical potentials to evaluate the liver function in the patients with hepatic disorders.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.1
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• pp.13-18
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• 2012

'Navigable airspace' means an airspace at and above the minimum safe flight level, including airspace or flight procedures needed for safe takeoff and landing. Airspace may be established as needed and may be abolished, and in some cases may be limited to airspace management. These are absolutely based on risk assessment. Safety is the state in which the risk of harm to persons or of property damage is reduced to, and maintained at or below, an acceptable level through a continuing process of hazard identification and risk management. 'Risk' is the assessed potential for adverse consequences resulting from a hazard and 'Risk assessment' involves consideration of both the frequency and the severity of any adverse consequence. This paper proposed 'risk assessment procedure' for the structural changes of Navigable Airspaces through literature reviews relevant to manuals on airspace management and risk management.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.10a
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• pp.234-241
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• 1995

Offshore structures are exposed to higher probability of collision with ship because of their limited mobility. In general, the consequence of the collision is reported to be relatively small and it is desirable to consider minor collisions in the design stage. It is important to have a comprehensive understanding of the dynamic responses of a tubular, their main member, under collision to design offshore structure against possible accidents. It is needed to estimate the probable extent of damage of a tubular, depth of dent, affected by the time history of impact load in ender to design a tubular strong enough for collision. In this paper, dynamic behaviors of a tubular due to the lateral impact are investigated through the numerical simulations with hydrocode DYNA3D, a three dimensional elasto-plastic large deformation impact contact problem analyzing program.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.558-564
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• 2006

When vehicles pass the connection between the bridge and earthwork, the difference of both sections' stiffness produces an increasing wheelload. As a consequence, it results in the excessive vibration of vehicles and the damage of bearing system. In general, steel plate girder railway bridges without ballast track have larger stiffness than the bridge with ballast, and produces larger impulse on the bridge superstructure. Thus, it is necessary to reduce the differences of both stiffness. This study presents parametric studies on the behavior of plate girder bridges and their tracks by means of various stiffnesses and the length of approach zone. The results of numerical study showed that the smaller the stiffness of both sides and the longer the length of approach zone, the variation of wheelload becomes smaller. Hence, it gives less burden into the plate girder bridges and their tracks. It is expected that the results of parametric study can be used as a preliminary data for the determination of economical length on the approach zone and the stiffness of both sides.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.683-686
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• 2008

Flood damage has been increased due to the abnormal climate and extreme rainfall. So, quantitative and qualitative hydrologic data should be improved in oder to enhance accuracy of hydrologic forecast. However, research regarding hydrologic data have not been thorough enough. Therefore, in this study, monte carlo simulation was applied to rainfall runoff model to improve the reliability of runoff analysis and risk analysis. Rainfall-Stage-Discharge curve was developed as a consequence of MCS and it is possible to get correct rating curve for high water level.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.194-196
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• 2002

This paper deals with a proper installation methods of SPDs for information-oriented and computerized equipments. Since the information and computerized equipments have AC power lines and communication lines, the potential difference by lightning surge occurs between grounding points of the AC power lines and subscriber protectors, and it causes the flashover and damage. So, we have investigated the effect of the installation methods of surge protectors on the control of overvoltages, using a real-sized test circuit with a customer's facility. As a consequence, it was confirmed that the protection methods by installation of SPDs on the neighbor branch circuit was effective.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2803-2811
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• 2020

With the aging of nuclear reactors, embrittlement of the reactor pressure vessel (RPV) steel, as a consequence of routine operations, is highly probable. To ensure operational integrity and safety, prediction and mitigation of compromising damage, brought on by pressurized thermal shock (PTS) following an emergency procedure, is of utmost importance. Computational fluid dynamics (CFD) codes can be employed to predict these events and have therefore been an acceptable method for such assessments. In this paper, CFD simulations of a density driven ECC state in the ROCOM facility are analyzed. Obtained numerical results are validated with the experimental measurements. Considerable attention is attributed to the boundary conditions and their influence, specifically outlet definitions, in order to determine and adequately replicate the non-active pumps in the facility. Consequent analyses focused on initial conditions as well as on the temporal discretization and inner iterations. Disparities due to different turbulent modelling approaches are investigated for standard RANS models. Based on observed trends for different cases, a definitive simulation setup has been established, results of which have been ultimately compared to the measurements.

• International Journal of Highway Engineering
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• v.14 no.4
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• pp.63-72
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• 2012

PURPOSES : Hot-mix asphalt(HMA) concretes show a trend of strength increase at low temperature due to binder stiffness increase, but strength decrease below a ceratin low temperature. This is due to the differential thermal contraction(DTC) which is induced by a significant difference in coefficients of thermal contraction between aggregate and asphalt which is coated around the aggregate. This DTC damage is well known to occur in HMA concrete, but is not yet investigated in warm-mix asphalt(WMA) concretes. METHODS : To evaluate DTC damage on WMA in this study, the flexural strength($S_f$) of WMA concretes, which were produced at $30{\sim}40^{\circ}C$ lower temperature, was evaluated in comparison with that of HMA at -5, -15 and $-25^{\circ}C$. RESULTS : Most of WMA and HMA mixtures showed flexural strength increase down to $-15^{\circ}C$ and decrease below $-15^{\circ}C$. this type of strength reduction below $-15^{\circ}C$ can e explained as the effect of differential thermal contraction that is a consequence of the large difference in coefficients of thermal contraction between aggregate and asphalt. the property reduction of WMA is similar the result of previous works dealt with HMA mixtures. CONCLUSIONS : Even though there is some differences by materials used, the WMA concretes showed a significantly lower DTC damage than HMA concrete at low temperature at ${\alpha}$=0.05 level.

• The Korean Society of Law and Medicine
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• v.10 no.1
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• pp.213-260
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• 2009

While the medical supplies have positive functions such as extending lifespan, recovering health, and preventing diseases, they also cause unexpected tragic consequences due to their side effects, and the magnitude of such damage inevitably increases due to the mechanism of mass production, mass distribution, and mass consumption of those medical supplies. Therefore, needless to say, the optimal way to prevent or reduce such damage is rather through medical supply manufacturers' producing non-defective products, or through the government's controlling production and sales of medical supplies with more aggressive exercise of regulatory authority on medical supply manufacturers, than through a remedy by a legal relief after using medical supplies. In this case, although the victim died due to the defect of the cold medicine, 'CONTAC 600', the drug company's responsibility to cover damages was not recognized because a defect could not be found in the then-manufacturing process. Thus, while pharmaceutical companies are gaining economic profits by producing and selling a medical supplies, if they do not take any remedy measures for the victims of their products' side effects, the victims have to use medical supplies under their own responsibility of taking a risk, and they have to accept the full damage of the potential consequence. Therefore, to remove such absurdity and contradiction, and to practically remedy the victim of medical supplies' side effects, the pharmaceutical side effects remedy project pending in the the Drugs, Cosmetics and Medical Instruments Lawneeds to be actively implemented.