• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.947-956
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• 2018

This research has been conducted to design upright parts of hand-made vehicles with the purpose of reducing material and machining cost while ensuring structural safety. Aluminum knuckles were modelled with three parts in order to enhance design flexibility as well as to reduce CNC machining cost. A vehicle model was constructed in CAD program and simulated in ADAMS View in order to estimate joint forces developing during 20 degree step steering condition at 60km/h. The joint forces obtained in the vehicle dynamics simulation were used for the structural analysis in ANSYS and dimensions of knuckle parts were adjusted until the lowest safety factor reached 2.0. The weight of knuckle decreased by 50% compared to the previous version that was designed without the structural analysis. The overall manufacturing cost decreased by 33% due to the reduction in the material as well as the CNC machining effort.

• BMB Reports
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• v.56 no.5
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• pp.287-295
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• 2023

The tumor microenvironment (TME) is a complex system composed of many cell types and an extracellular matrix (ECM). During tumorigenesis, cancer cells constantly interact with cellular components, biochemical cues, and the ECM in the TME, all of which make the environment favorable for cancer growth. Emerging evidence has revealed the importance of substrate elasticity and biomechanical forces in tumor progression and metastasis. However, the mechanisms underlying the cell response to mechanical signals-such as extrinsic mechanical forces and forces generated within the TME-are still relatively unknown. Moreover, having a deeper understanding of the mechanisms by which cancer cells sense mechanical forces and transmit signals to the cytoplasm would substantially help develop effective strategies for cancer treatment. This review provides an overview of biomechanical forces in the TME and the intracellular signaling pathways activated by mechanical cues as well as highlights the role of mechanotransductive pathways through mechanosensors that detect the altering biomechanical forces in the TME.

• Wind and Structures
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• v.25 no.2
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• pp.177-193
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• 2017

The accelerated development of new materials, technologies and construction processes, in parallel with advances in computational algorithms and ever growing computational power, is leading to more daring and innovative architectural and structural designs. The search for non-regular building shapes and slender structures, as alternative to the traditional architectural forms that have been prevailing in the building sector, poses important engineering challenges in the assessment of the strength and mechanical stability of non-conventional structures and systems, namely against highly variable actions as wind and seismic forces. In case of complex structures, laboratory experiments are a widely used methodology for strength assessment and loading characterization. Nevertheless, powerful numerical tools providing reliable results are also available today and able to compete with the experimental approach. In this paper the wind action on a free-form complex thin shell is investigated through 3D-CFD simulation in terms of the pressure coefficients and global forces generated. All the modelling aspects and calibrating process are described. The results obtained showed that the CFD technique is effective in the study of the wind effects on complex-shaped structures.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.1024-1040
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• 2014

The theoretical background and a numerical solution procedure for a time domain hydroelastic code are presented in this paper. The code combines a VOF-based free surface flow solver with a flexible body motion solver where the body linear elastic deformation is described by a modal superposition of dry mode shapes expressed in a local floating frame of reference. These mode shapes can be obtained from any finite element code. The floating frame undergoes a pseudo rigid-body motion which allows for a large rigid body translation and rotation and fully preserves the coupling with the local structural deformation. The formulation relies on the ability of the flow solver to provide the total fluid action on the body including e.g. the viscous forces, hydrostatic and hydrodynamic forces, slamming forces and the fluid damping. A numerical simulation of a flexible barge is provided and compared to experiments to show that the VOF-based flow solver has this ability and the code has the potential to predict the global hydroelastic responses accurately.

• Journal of the Korea Safety Management & Science
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• v.12 no.1
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• pp.137-148
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• 2010

Aimed at fostering global human resource and utilizing it, this study presents a more systematic approach for encouraging overseas employment of the young generation. This study suggests a method for the objective evaluation of the overseas employment program through to used the M. Porter's 5-Forces and business administrative technologies. The result of this research will allow us to suggest a well-organized and more systematic frame of the international exchange programs, in which various new policies can be found. Since the overseas employment program is a non-standard, yet important, national policy plan, the future direction of the program was suggested based on the data of the previously-promoted programs.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.289-296
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• 2000

Dynamic responses of a bridge retrofitted with cable restrainers are examined under seismic excitations. A simplified and idealized mechanical model is developed to analyze the effects of the restrainers, which can consider the plastic behavior as well as the fracture of the cable. Using the proposed model, the effects of the stiffness and the clearance length of the restrainer upon the global bridge seismic behaviors are estimated. The changes of pounding forces, shear forces, and bending moments due to the application of restrainers are also investigated. The main effect of restrainers upon global bridge motions is found to reduce the relative distances between adjacent vibrations units. It is also found that the relative distances are decreased as the clearance length of the restrainer decreases and the stiffness of restrainer increases.

• International Journal of Stem Cells
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• v.16 no.3
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• pp.251-259
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• 2023

Mesenchymal stromal cells (MSCs) have attracted scientific and medical interest due to their self-renewing properties, pluripotency, and paracrine function. However, one of the main limitations to the clinical application of MSCs is their loss of efficacy after transplantation in vivo. Various bioengineering technologies to provide stem cell niche-like conditions have the potential to overcome this limitation. Here, focusing on the stem cell niche microenvironment, studies to maximize the immunomodulatory potential of MSCs by controlling biomechanical stimuli, including shear stress, hydrostatic pressure, stretch, and biophysical cues, such as extracellular matrix mimetic substrates, are discussed. The application of biomechanical forces or biophysical cues to the stem cell microenvironment will be beneficial for enhancing the immunomodulatory function of MSCs during cultivation and overcoming the current limitations of MSC therapy.

• Ocean Systems Engineering
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• v.5 no.3
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• pp.139-160
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• 2015

The global performance of the 5MW OC4 semisubmersible floating wind turbine in random waves was numerically simulated by using the turbine-floater-mooring fully coupled and time-domain dynamic analysis program FAST-CHARM3D. There have been many papers regarding floating offshore wind turbines but the effects of second-order wave-body interactions on their global performance have rarely been studied. The second-order wave forces are actually small compared to the first-order wave forces, but its effect cannot be ignored when the natural frequencies of a floating system are outside the wave-frequency range. In the case of semi-submersible platform, second-order difference-frequency wave-diffraction forces and moments become important since surge/sway and pitch/roll natural frequencies are lower than those of typical incident waves. The computational effort related to the full second-order diffraction calculation is typically very heavy, so in many cases, the simplified approach called Newman's approximation or first-order-wave-force-only are used. However, it needs to be justified against more complete solutions with full QTF (quadratic transfer function), which is a main subject of the present study. The numerically simulated results for the 5MW OC4 semisubmersible floating wind turbine by FAST-CHARM3D are also extensively compared with the DeepCWind model test results by Technip/NREL/UMaine. The predicted motions and mooring tensions for two white-noise input-wave spectra agree well against the measure values. In this paper, the numerical static-offset and free-decay tests are also conducted to verify the system stiffness, damping, and natural frequencies against the experimental results. They also agree well to verify that the dynamic system modeling is correct to the details. The performance of the simplified approaches instead of using the full QTF are also tested.

• Strategy21
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• s.32
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• pp.5-35
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• 2013

The purpose of this thesis is to suggest how to plan ROK(Republic of Korea) Navy's strategy concerning to JOAC(Joint Operation Access Concept) and ASB(Air-Sea Battle) concept of US(United States) armed forces. Since 2006, US armed forces has been developing CONOPS(Concepts of Operations), JOAC & ASB. These concepts will not only affect security environment for Korea Peninsula and West Pacific Area, but also will be affected to ROK Navy's Strategy. Therefore, Korea Navy has to consider and review those concepts and should discuss the way to secure peace of Korea Peninsula. JOAC & ASB have been developed for securing operational access ability of US armed forces against enemy forces. A2/AD(Anti-Access, Area-Denial) is the strategy of possible enemy forces against US forces' approaching into the operation area and impede operations within area. US forces had to overcome enemy's A2/AD strategy in coming century to protect national interest and sustain global leadership. The main concept of JOAC & ASB is "Cross-domain Synergy", which means 'to eliminate duplicate and improve joint operability containing space and cyber operation area.' Korea Navy's acceptance of JOAC & ASB without any revising is not a rational choice. Without the amendment some problems can be occurred by the Korea navy's acceptance for the original version of JOAC & ASB. Those are "Missing differences of operation environment between Korea and US", "Impediment from neighbor nations, especially PRC (People's Republic of China)", and "Impediment inside from Korea armed forces". Therefore, Korea Navy has to evaluate and find out the way to solve for JOAC & ASB to apply for their strategy and minimise those possible problems above. This thesis is expected to be the solution.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.3
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• pp.290-301
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• 2013

The docking analysis of a global ship structure is requested to evaluate its structural safety against the reaction forces at supports during docking works inside a dry dock. That problem becomes more important recently as the size of ships is getting larger and larger. The docking supports are appropriately arranged in a dock to avoid their excessive reaction forces which primarily cause the structural damages in docking a ship and, up to now, the structural safety has been assessed against the support arrangement by the finite element analysis (FEA) of a global ship structure. However, it is complicated to establish the finite element model of the ship in the current structural design environment of a shipyard and it takes over a month to finish the work. This paper investigates a simple and fast approach to carry out a ship docking analysis by a simplified grillage model and to assign the docking supports position on the model. The grillage analysis was considered from the motivation that only the reaction forces at supports are sufficient to assess their arrangement. Since the simplified grillage model of the ship cannot guarantee its accuracy quantitatively, modeling strategies are proposed to improve the accuracy. In this paper, comparisons between the proposed approach and three-dimensional FEA for typical types of ships show that the results from the present grillage model have reasonably good agreement with the FEA model. Finally, an integrated program developed for docking supports planning and its evaluation by the proposed approach is briefly described.