• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.547-555
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• 2019

The purpose of this study was to establish a numerical model of polyurethane foam (PUF) to simulate the dynamic response and strength of membrane-type Liquefied natural gas (LNG) Cargo containment system (CCS) under the impact load. To do this, initially, the visco-plastic behavior of PUF was characterized by testing the response of the PUF to the impact loads with various strain rates as well as PUF densities at room temperature and at cryogenic conditions. A PUF material model was established using the test results of the material and the FE analysis. To verify the validation of the established material model, simulations were performed for experimental applications, e.g., the dry drop test, and the results of FEA were compared to the experimental results. Based on this comparison, it was found that the dynamic response of PUF in dry drop tests, such as the reaction force and fracture behaviors, could be simulated successfully by the material model proposed in this study.

• Journal of Welding and Joining
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• v.26 no.6
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• pp.74-80
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• 2008

A finite element modeling approach has been described for the simulation and analysis of the micron-scaled solid particle impact behavior in kinetic spraying process, using an explicit code (ABAQUS 6.7-2). High-strain-rate plastic deformation and interface bonding features of the copper, nickel, aluminum, and titanium were investigated via FEM in conjunction with the Johnson-Cook plasticity model. Different aspects of adiabatic shear instabilities of the materials were characterized as a concept of thermal boost-up zone (TBZ), and also discussed based upon energy balance concept with respect to relative recovery energy (RRE) for the purpose of optimizing the bonding process.

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.614-621
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• 2012

Silver nanoparticles production by the green chemistry approach was investigated using an isolated marine actinomycetes strain. The isolated strain was identified as Streptomyces albidoflavus based on chemotaxonomic and ribotyping properties. The strain revealed production of silver nanoparticles both extracellular and intracellularly. Surface Plasmon Resonance analysis with the function of time revealed that particle synthesis by this strain is reaction time dependent. The produced particles were spherical shaped and monodispersive in nature and showed a single surface plasmon resonance peak at 410 nm. Size distribution histograms indicated production of 10-40-nm-size nanoparticles with a mean size of 14.5 nm. FT-IR spectra of nanopartilces showed N-H, C-H, and C-N stretching vibrations, denoting the presence of amino acid/peptide compounds on the surface of silver nanoparticles produced by S. albidoflavus. Synthesized nanoparticles revealed a mean negative zeta potential and electrophoretic mobility of -8.5 mV and -0.000066 $cm^2/Vs$, respectively. The nanoparticles produced were proteinaceous compounds as capping agents with -8.5 mV zeta potential and revealed antimicrobial activity against both Gram-negative and -positive bacterial strains. Owing to their small size, these particles have greater impact on industrial application spectra.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1311-1317
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• 2014

This is a descriptive study that attempts to provide basic information for easing job strain and enhancing the efficiency of cosmetology industry workers by examining the effects that the emotional labor and stress-coping of cosmetology workers have on their job strain. As a result of a multiple regression analysis of the factors affecting the subjects job strain, their surface acting and problem-focused coping, unconcern coping, social support were seen as factors that accounted for 30% of their job strain. Of the emotional labor of the subjects, the external behaviors displayed positive correlations with job strain; and they showed negative correlations with problem-focused coping and social support. Concerning emotional labor, sincere behavior was found to have positive correlations with problem-focused coping, hoping, social support, positive coping and strain relieving. Based on the results of this study, it is deemed that, along with interventions for emotional labor, education and intervention programs for a healthy and positive stress coping are needed in regards to interventions for cosmetology professionals.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1520-1526
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• 2002

The Charpy and Izod impact tests are the most prevalent techniques used to characterize the effects of high impulse loads on ploymeric materials. An analysis method for rubber toughened PVC is suggested to evaluate critical dynamic strain energy release rates(G$\_$c/) from the Charpy impact energy measurements. An instrumented Charpy impact tester was used to extract ancillary information concerning fracture parameters in addition to total fracture energies and maximum critical loads. The dynamic stress intensity factor Kid was computed for varying amounts of rubber contents from the obtained maximum critical loads and also toughening effects were investigated as well.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4677-4684
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• 2010

In this study, the safety of passenger could be investigated by the analysis of car body to absorb he shock onto automotive door. The damage at door happens because of the collision of automotive door or parking accident due to the carelessness of driver. This door was modelled by CATIA program. The damage process of this model by impact was analyzed and investigated through ANSYS program. The contours of equivalent stress and strain were obtained. It can be known how damage of door becomes under impact and this study result can be thought to contribute for the design of door considering impact safety.

• The Journal of the Korea Contents Association
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• v.20 no.8
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• pp.251-261
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• 2020

This study aims to suggest a new perspective that can account for variations in fertility rates across OECD countries. Most previous literature has highlighted the influence of government policies on fertility rates. This study focuses the role of job strain, unequal division of household labor, and life satisfaction on fertility rates. These factors are related to work-life balance, and play a crucial role in understanding variations in fertility rates across OECD countries. Using fuzzy set qualitative comparative research analysis (fsQCA), this study tests whether fertility rates can be explained by differences in the levels of job strain, gender equality at home, and life satisfaction across countries. The results are as follows: First, high fertility-countries show low levels of job strain, equal division of household labor, high levels of life satisfaction, and high levels of GDP. Second, a high level of GDP is not crucial for achieving high fertility rates. This study suggests that changes in working conditions and organizational culture are required to increase the fertility rate in Korea, since this can influence work-life balance, life satisfaction and equal division of household labor.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.735-749
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• 2008

For the development of the original technique of structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In the previous study, the wet drop impact response analyses of CCS structure in membrane Mark III type LNG carriers were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. In this study, the characteristics of structural shock response behaviors of CCS structure were sufficiently figured out by careful examinations of the effects of specimen weight, drop height, incident angle, corrugation and stiffness of inner hull on its shock response behaviors. The shock response analysis of upward shooting fluid to inner hull was performed, and the reason of faster strain response than shock pressure one was also figured out.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.1-6
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• 2017

Ballistic impact on a soldier wearing a helmet can induce fatal injury, even if the helmet is not penetrated. Although studies on this type of injury have been performed, most of them have used an analytical model focused on head injury only. The injury of the neck muscles and cervical vertebrae by non-penetrating ballistic impact affects the survivability of soldiers, despite not inflicting fatal injury to the human body. Therefore, an analytical model of the head and neck muscles are necessary. In this study, an analysis of human body injury using the previously developed head model, as well as a cervical model with muscles, was performed. For the quantitative prediction of injury, the stress, strain, and HIC were compared. The results from the model including the cervical system indicated a lower extent of injury than the results from the model excluding them. The results of head injury were compared with other references for reliability.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.1079-1092
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• 2020

A parametric study of several parameters relevant to design safety on the spent nuclear fuel (SNF) rod response under a drop accident is presented. In the view of the complexity of interactions between the independent safety-related parameters, a factorial design of experiment is employed as an efficient method to investigate the main effects and the interactions between them. A detailed single full-length fuel rod is used with consideration of post-irradiated fuel conditions under horizontal and vertical free-drops onto an unyielding surface using finite-element analysis. Critical drop heights and critical g-loads that yield the threshold plastic strain in the cladding are numerically estimated to evaluate the fuel rod structural resistance to impact load. The combinatory effects of four uncertain parameters (pellet-cladding interfacial bonding, material properties, spacer grid stiffness, rod internal pressure) and the interactions between them on the fuel rod response are investigated. The principal finding of this research showed that the effects of above-mentioned parameters on the load-carrying capacity of fuel rod are significantly different. This study could help to prioritize the importance of data in managing and studying the structural integrity of the SNF.