• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.4
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• pp.279-285
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• 2012

In this paper a computational method for a homogenized peridynamics description of unidirectional fiber-reinforced composites is presented. For these materials, dynamic brittle fracture and damage are simulated with the proposed peridynamic model. Compared with observations from dynamic experiments by Coker et al.(2001), the peridynamic computational model can reproduce various characteristics of dynamic fracture and supersonic or intersonic crack growth in asymmetrically loaded unidirectional fiber-reinforced composite plates. Also we analyze the same model in the symmetric loading condition and figure out that the asymmetric loading leads to a much higher propagation speed. Consistent results have been reported in the experiments.

• Earthquakes and Structures
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• v.13 no.6
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• pp.539-549
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• 2017

Existing reinforced concrete frame buildings designed for vertical loads could only suffer severe damage during earthquakes. In recent years, many research activities were undertaken to develop a reliable and practical analysis procedure to identify the safety level of existing structures. The Incremental Dynamic Analysis (IDA) is considered to be one of the most accurate methods to estimate the seismic demand and capacity of structures. However, the executions of many nonlinear response history analyses (NL_RHA) are required to describe the entire range of structural response. The research discussed in this paper deals with the proposal of an efficient Incremental Modal Pushover Analysis (IMPA) to obtain capacity curves by replacing the nonlinear response history analysis of the IDA procedure with Modal Pushover Analysis (MPA). Firstly, In this work, the MPA is examined and extended to three-dimensional asymmetric structures and then it is incorporated into the proposed procedure (IMPA) to estimate the structure's seismic response and capacity for given seismic actions. This new procedure, which accounts for higher mode effects, does not require the execution of complex NL-RHA, but only a series of nonlinear static analysis. Finally, the extended MPA and IMPA were applied to an existing irregular framed building.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.573-578
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• 2019

Anisotropic distribution of the turbulent kinetic energy and the near-field excitations are the main causes of the steady state Flow-Induced Vibration (FIV) which could lead to fretting wear damage in vertically arranged supported slender rods. In this article, a combined Computational Fluid Dynamics (CFD) and Computational Structural Mechanic (CSM) approach named two-way Fluid-Structure Interaction (FSI) is used to investigate the modal characteristics of a typical rod's vibration. Performance of an Unsteady Reynolds-Average Navier-Stokes (URANS) and Large Eddy Simulation (LES) turbulence models on asymmetric fluctuations of the flow field are investigated. Using the LES turbulence model, any large deformation damps into a weak oscillation which remains in the system. However, it is challenging to use LES in two-way FSI problems from fluid domain discretization point of view which is investigated in this article as the innovation. It is concluded that the near-wall meshes whiten the viscous sub-layer is of great importance to estimate the Root Mean Square (RMS) of FIV amplitude correctly as a significant fretting wear parameter otherwise it merely computes the frequency of FIV.

• Korea Trade Review
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• v.44 no.3
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• pp.105-121
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• 2019

This study applies diverse game theories to the US-China Trade War. The US-China Trade War can be analyzed as a game situation because the strategic decision-making process to maximize one's profit while considering the reaction of the other party is a game situation. However, related research suffered from some mistakes in applying the US-China Trade War as it is to classic game theory, because while the prisoners dilemma is based on the situation of No Communication, No Trust, No Cooperation, the US-China Trade War has a precondition different from that of prisoners dilemma, since it mutually communicates information and negotiation is repeated several times in a cooperative situation. The result of the trade negotiation will likely end as 'cooperate-cooperate'. Further, considering trade volume, trade interdependence, bargaining power based on economy, and the scale of damage caused by the Trade War, the US-China Trade War is progressing with the bargaining power of the US being higher than that of China. Since the current US-China Trade War is in an asymmetrical situation under the dominant bargaining power of the US, it is likely to reach 'US defect-China cooperative' in the long run.

• KEPCO Journal on Electric Power and Energy
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• v.3 no.2
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• pp.79-88
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• 2017

In this paper, the wind tunnel test for the measurement of aerodynamic characteristics of transmission conductors with asymmetric sections is described. A single conductor model and bundled conductor models with ice accreted shapes are tested both in steady and turbulent flow, and the aerodynamic coefficients are acquired. Transmission conductor galloping is a kind of wind-induced vibration which is characterized by primarily vertical oscillation with a very low frequency and a high amplitude. It is well known that transmission conductor galloping is generally caused by moderately strong, steady winds when a transmission conductor has an asymmetric cross-section shaped by accreted ice. Galloping should be considered from the design stage of overhead lines because it can cause severe wear and fatigue damage to attachments as well as transmission conductors. It is reported that there have been normally 20 events of galloping per year in Korea, which may be followed by serious consequences in the electric power system. Therefore, this research is performed to measure aerodynamic characteristics of ice accreted transmission conductors to understand and control transmission conductor galloping so that it would help to prevent unexpected failures and reduce the maintenance costs caused by galloping.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.1-14
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• 2004

The seismic behavior of a 1/3-scale model of a two-story unreinforced masonry (URM) structure typically used in constructing low-rise residential buildings in Korea is studied through a shaking table test. The purposes of this study are to investigate seismic behavior and damage patterns of the URM structure that was not engineered against seismic loading and to provide its experimental test results. The test structure was symmetric about the transverse axis but asymmetric to some degrees about longitudinal axis and had a relatively strong diaphragm of concrete slab. The test structure was subjected to a series of differentlevels of earthquake shakings that were applied along the longitudinal direction. The measured dynamic response of the test structure was analyzed in terms of various global parameters (i.e., floor accelerations, base shear, floor displacements and storydrift, and torsional displacements) and correlated with the input table motion. Moreover, different levels of seismic performance were suggested for performance-based design approach. The results of the shaking table test revealed that the shear failure was dominant on a weak side of the 1stfloor while the upper part of the test model remained as a rigid body. Also, it was found that substantial strength and deformation capacity existed after cracking.

• Biomolecules & Therapeutics
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• v.26 no.3
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• pp.282-289
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• 2018

Melanin is a pigment produced from tyrosine in melanocytes. Although melanin has a protective role against UVB radiation-induced damage, it is also associated with the development of melanoma and darker skin tone. Tyrosinase is a key enzyme in melanin synthesis, which regulates the rate-limiting step during conversion of tyrosine into DOPA and dopaquinone. To develop effective RNA interference therapeutics, we designed a melanin siRNA pool by applying multiple prediction programs to reduce human tyrosinase levels. First, 272 siRNAs passed the target accessibility evaluation using the RNAxs program. Then we selected 34 siRNA sequences with ${\Delta}G{\geq}-34.6kcal/mol$, i-Score value ${\geq}65$, and siRNA scales score ${\leq}30$. siRNAs were designed as 19-bp RNA duplexes with an asymmetric 3' overhang at the 3' end of the antisense strand. We tested if these siRNAs effectively reduced tyrosinase gene expression using qRT-PCR and found that 17 siRNA sequences were more effective than commercially available siRNA. Three siRNAs further tested showed an effective visual color change in MNT-1 human cells without cytotoxic effects, indicating these sequences are anti-melanogenic. Our study revealed that human tyrosinase siRNAs could be efficiently designed using multiple prediction algorithms.

• Fire Science and Engineering
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• v.34 no.1
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• pp.89-102
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• 2020

Chemical terrorism using toxic and flammable gases, which could be fatal to the health of the human body, poses a serious threat to the security of most advanced countries, as well as those that are suffering from local disputes, due to the asymmetric information that exists between terrorist actors and victims. The countermeasures against chemical terrorism can be roughly divided into three stages: prevention, response, and probation. The critical factors for each professional response agency, and the personnel that determine the degree and range of chemical terrorism damage, are performing missions successfully in the process of the prevention and the response stage against chemical terrorism. To do this, conducting objective and systematical assessments on facilities that could potentially be the subject of chemical terrorism is more important than anything. In this study, we compared the existing domestic and foreign vulnerable classification systems for chemical terrorism, reviewed the current direction of improvement in domestic classification systems, and suggested more scientific and systematic methodologies through the vulnerability assessment on an actual public facility sample.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.3
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• pp.281-287
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• 2011

This paper explains the basic theory and a new development of for the residual strength prediction program of the asymmetrically damaged ships, being capable of searching moment-curvature relations considering neutral axis mobility. It is noted that moment plane and neutral axis plane should be separately defined for asymmetric sections. The validity of the new program is verified by comparing moment-curvature curves of 1/3 scaled frigate model where the results from new algorithm well coincide with experimental and nonlinear FEA results for intact condition and with nonlinear FEA results for damaged condition. Applicability of new algorithm is also verified by applying VLCC model to the newly developed program. It is proved that reduction of residual strengths is visually presented using the new algorithm when damage specifications of ABS, DNV and IMO are applied. It is concluded that the new algorithm shows very good performance to produce moment-curvature relations with neutral axis mobility on the asymmetrically damaged ships. It is expected that the new program based on the developed algorithm can largely reduce design period of FE modeling and increase user conveniences.

• Convergence Security Journal
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• v.18 no.2
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• pp.133-139
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• 2018

The 5 Game changer means the concepts of the army's operation against the enemy's asymmetric threats so that minimize damage to the public and leads to victory in war in the shortest time. A study of network architecture of Dronebot operation is a key study to carry out integrated operation with integrated C4I system by organically linking several drones battle groups through ICT. The NBC reconnaissance drones can be used instead of vehicles and humans to detect NBC materials and share situations quickly. However, there is still a lack of research on the swarm flight of the NBC reconnaissance drones and the weaknesses of cyber electronic warfare. In this study, we present weaknesses and countermeasures of CBRNs in swarm flight operations and provide a basis for future research.