• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.309-316
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• 2015

A state-based peridynamic model is able to describe a general constitutive model from the standard continuum theory. The response of a material at a point is dependent on the deformation of all bonds connected to the point within the nonlocal horizon region. Therefore, the state-based peridynamic model permits both the volume and shear changes of the material which is promising to reproduce the complicated dynamic brittle fracture phenomena, such as crack branching, secondary cracks, cascade cracks, crack coalescence, etc. In this paper, the two-dimensional state-based peridynamic model for a linear elastic plane stress solid is employed. The damage model incorporates the energy release rate and the peridynamic energy potential. For brittle glass materials, the impact of the crack-parallel compressive stress waves on the crack branching pattern is investigated. The peridynamic solution for this problem captures the main features, observed experimentally, of dynamic crack propagation and branching. Cascade cracks under strong tensile loading and secondary cracks are also well reproduced with the state-based peridynamic simulations.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2221-2224
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• 2013

The glutathione S-transferases (GSTs) are a family of enzymes involved in the detoxification of a wide range of chemicals, including important environmental carcinogens, as well as chemotherapeutic agents. In the present study 294 acute leukemia cases, comprising 152 of acute lymphocytic leukemia (ALL) and 142 of acute myeloid leukemia, and 251 control samples were analyzed for GSTM1 and GSTT1 polymorphisms through multiplex PCR methods. Significantly increased frequencies of GSTM1 null genotype (M0), GSTT1 null genotype (T0) and GST double null genotype (T0M0) were observed in the both ALL and AML cases as compared to controls. When data were analyzed with respect to clinical variables, increased mean levels of WBC, Blast %, LDH and significant reduction in DFS were observed in both ALL and AML cases with T0 genotype. In conclusion, absence of both GST M & GST T might confer increased risk of developing ALL or AML. The absence of GST enzyme might lead to oxidative stress and subsequent DNA damage resulting in genomic instability, a hallmark of acute leukemia. The GST enzyme deficiency might also exert impact on clinical prognosis leading to poorer DFS. Hence GST genotyping can be made mandatory in management of acute leukemia so that more aggressive therapy such as allogenic stem cell transplantation may be planned in the case of patients with a null genotype.

• Journal of the Society of Disaster Information
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• v.8 no.1
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• pp.47-55
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• 2012

There are currently various domestic high-rise construction projects underway. Such projects may maximize the economic impact, and yield other benefits, however, there is also a possibility of fire, terrorism, and other disasters that one may not even imagine. This study of high-rise structures' damage reduction measures the fire-fighting ability of the fire fighters at the scene of an indoor emergency upon entry. In order to identify the practical limitations, the fire fighter entered from the 1st floor to reach the top 54th floor. 1.Time required to reach the top floor without the respirator 2.Time required as well as pressure consumption to reach the top floor with the respirator equipped was measured; based on the results, performable range of operations during a fire fighting activity were presented.

• Journal of the Korea Safety Management & Science
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• v.15 no.3
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• pp.37-50
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• 2013

It is not an exaggeration to say that modern chemicals take a leading place in our life, and people live with the chemicals, having a huge impact on their daily life. The chemical industry in South Korea, ranked seventh in the world, is one of the key industries that are forming greater part of Korean economy. The actual state of the chemical industries, however, is that over 14 tons of hazardous chemicals are being discharged annually and threaten people's lives with a lack of knowledge of its potential danger. In this way, not only beneficial to us, some of these substances, All chemicals, but also present a threat fundamentally our living environment to hazards to human health and the environment, accidents such chemicals, unlike accidents general understanding the scale of damage and propagation velocity has a complex very difficult risk profile, that can occur during deployment of an accident type is also very diverse. Is the actual situation of public concern against harmful chemicals management's is amplified by the chemical accident in the wake such accidents, government and corporate and reactive system and management system prior to the chemical accident the need for communication to exchange ideas with each other between residents, providing information is important. Therefore, the government departments and corporations, which manage variety of chemicals, ought to contribute toward a development of national security by rigid control over the Hazardous chemicals.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.2
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• pp.92-102
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• 1998

Prediction of failure behavior in filament-wound composite motor cases is one of the important issues for their reliable application. Acoustic emission during hydroproof testing of the cases is used to solve this problem. Based on the acoustic emission behavior, failure sites can be located successfully. The identification of failure modes is also possible using the distribution of acoustic emission amplitude. Due to the limitation in the number of samples, it is not possible to predict the final burst pressure of motor cases and the effect of impact damage on the final burst pressure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1027-1034
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• 2016

In this research, experimental study about size effect of solid particles on erosion resistance is presented. A high-density polyethylene particle with a mm-sized diameter is accelerated using a two-stage light gas gun up to Mach number of approximately 3.0. An accelerated particle impacts aluminum alloy such as Al1050 and Al6061 T6, and infrared windows such as ZnS and sapphire specimens. For the aluminum alloy, craters that form on the surface of the specimens are measured to characterize the erosion resistance of the material. For the infrared windows, repetitive tests are conducted until a linear or circumferential crack is found to create damage threshold curves that define a material's erosive resistance. From the comparison of test data for various sizes of high-density polyethylene particles, it is found that erosion resistance of material is linearly dependent on the size of particles.

• Smart Structures and Systems
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• v.21 no.4
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• pp.479-491
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• 2018

Shape memory alloys (SMA) exhibit superelasticity which refers to the capability of entirely recovering large deformation upon removal of applied forces and dissipating input energy during the cyclic loading reversals when the environment is above the austenite finish temperature. This property is increasingly favored by the earthquake engineering community, which is currently developing resilient structures with prompt recovery and affordable repair cost after earthquakes. Compared with the other SMAs, NiTi SMAs are widely deemed as the most promising candidate in earthquake engineering. This paper contributes to evaluate the seismic performance of properly designed concentrically braced frames (CBFs) equipped with NiTi SMA braces under earthquake ground motions corresponding to frequently-occurred, design-basis and maximum-considered earthquakes. An ad hoc seismic design approach that was previously developed for structures with idealized SMAs was introduced to size the building members, by explicitly considering the strain hardening characteristics of NiTi SMA particularly. The design procedure was conducted to compliant with a suite of ground motions associated with the hazard level of design-basis earthquake. A total of four six-story CBFs were designed by setting different ductility demands for SMA braces while designating with a same interstory drift target for the structural systems. The analytical results show that all the designed frames successfully met the prescribed seismic performance objectives, including targeted maximum interstory drift, uniform deformation demand over building height, eliminated residual deformation, controlled floor acceleration, and slight damage in the main frame. In addition, this study indicates that the strain hardening behavior does not necessarily impose undesirable impact on the global seismic performance of CBFs with SMA braces.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.56-64
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• 2016

Damage of sea-crossing bridge by ship collision is related to estimate frequencies of overloading due to impact, and bridge accordingly must be designed to satisfy related acceptance criteria. Another important aspect is the management on increment of collision risk during the service period. In this study, related plan, main span length, air draft clearance and collision risk are analyzed for the interim assessment of Incheon Bridge focusing on the ship collision problem. In particular, for the increment of collision risk, the optimized navigation speed is proposed by reviewing the research findings and navigation guidelines etc. as a temporary expedient. Also basic procedure for reasonable prediction of target vessel and passage is established and probabilistic prediction method to embrace the uncertainty of the prediction is proposed as a fundamental solution. It is necessary to conduct further research on collision risk management and promptly carry out interim assessments of other marine bridges.

• Korean Journal of Construction Engineering and Management
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• v.18 no.2
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• pp.108-116
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• 2017

It is expected that the maintenance cost of domestic bridges will increase considerably due to the increase of bridge service time. In response to this situation, the government and relevant ministries are focusing on developing ways to efficiently allocate limited budgets and to rationally select maintenance bridge. In this study, to develop a risk - based bridge maintenance priority decision model, 14 common risk factors causing damage to bridges were extracted and AHP analysis was performed to select 5 important factors. Based on the existing literature review and expert consultation, we derive the evaluation criteria and the impact weights of the selected factors, and based on this, I presented risk based bridge maintenance priority model. Using this model in combination with existing maintenance priority methods will lead to more reasonable bridge maintenance priorities.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.89-95
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• 2016

Keeping the gas pipelines in the common utility tunnel is useful because it has a lower risk of corrosion than conventional burial, and can prevent from excavating construction. But, explosions in common utility tunnels can cause greater damage from the blast overpressure compared to outdoor explosions, due to nature of the confined environment. Despite this fact, however, research on common utility tunnels has been limited to fire hazard and little has been studied on the dangers of explosions. This study developed scenarios of methane gas explosion caused by gas leak from gas piping within the common utility tunnel followed by unknown ignition; the study then calculated the extent of the impact of the explosion on the facilities above, and suggested the needs for designing additional safety measures. Two scenarios were selected per operating condition of safety devices and the consequence analysis was carried out with FLACS, one of the CFD tools for explosion simulation. The overpressures for all scenarios are substantial enough to completely destroy most of the buildings. In addition, we have provided additional measures to secure safety especially reducing incident frequency.