• International Journal of High-Rise Buildings
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• v.7 no.4
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• pp.375-387
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• 2018

This paper presents a review on progressive collapse mechanism of steel framed buildings exposed to fire. The influence of load ratios, strength of structural members (beam, column, slab, connection), fire scenarios, bracing systems, fire protections on the collapse mode and collapse time of structures is comprehensively reviewed. It is found that the key influencing factors include load ratio, fire scenario, bracing layout and fire protection. The application of strong beams, high load ratios, multi-compartment fires will lead to global downward collapse which is undesirable. The catenary action in beams and tensile membrane action in slabs contribute to the enhancement of structural collapse resistance, leading to a ductile collapse mechanism. It is recommended to increase the reinforcement ratio in the sagging and hogging region of slabs to not only enhance the tensile membrane action in the slab, but to prevent the failure of beam-to-column connections. It is also found that a frame may collapse in the cooling phase of compartment fires or under travelling fires. This is because that the steel members may experience maximum temperatures and maximum displacements under these two fire scenarios. An edge bay fire is more prone to induce the collapse of structures than a central bay fire. The progressive collapse of buildings can be effectively prevented by using bracing systems and fire protections. A combination of horizontal and vertical bracing systems as well as increasing the strength and stiffness of bracing members is recommended to enhance the collapse resistance. A protected frame dose not collapse immediately after the local failure but experiences a relatively long withstanding period of at least 60 mins. It is suggested to use three-dimensional models for accurate predictions of whether, when and how a structure collapses under various fire scenarios.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.142-143
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• 2019

Busan Port ranked 6th in the world with 21.67 million TEUs of container handling in 2018, but the ship supply industry has fallen short of that. Despite its technological prowess, Korea's ship supply industry lacks competitive edge in many aspects such as government support, integrated platform, and infrastructure compared to overseas ship supply industries. The use of code, which is not standardized, can be cited as a leading factor that undermines the competitiveness of Korea's ship supply industries. In the ship supply industry, the use of non-standardized codes can make it difficult to manage or analyze meaningful statistics, and, by extension, can lead to the loss of new business opportunities. Therefore, in this study, we intend to use local ship supply transaction data to study how to standardize item code to solve the problem.

• Food Engineering Progress
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• v.21 no.3
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• pp.233-241
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• 2017

Scaffolds of cell substrates are biophysical platforms for cell attachment, proliferation, and differentiation. They ultimately play a leading-edge role in the regeneration of tissues. Recent studies have shown the potential of bioactive scaffolds (i.e., osteo-inductive) through 3D printing. In this study, rice bran-derived biocomposite was fabricated for fused deposition modeling (FDM)-based 3D printing as a potential bone-graft analogue. Rice bran by-product was blended with poly caprolactone (PCL), a synthetic commercial biodegradable polymer. An extruder with extrusion process molding was adopted to manufacture the newly blended "green material." Processing conditions affected the performance of these blends. Bio-filament composite was characterized using field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX). Mechanical characterization of bio-filament composite was carried out to determine stress-strain and compressive strength. Biological behaviors of bio-filament composites were also investigated by assessing cell cytotoxicity and water contact angle. EDX results of bio-filament composites indicated the presence of organic compounds. These bio-filament composites were found to have higher tensile strength than conventional PCL filament. They exhibited positive response in cytotoxicity. Biological analysis revealed better compatibility of r-PCL with rice bran. Such rice bran blended bio-filament composite was found to have higher elongation and strength compared to control PCL.

• Journal of the Korea Fashion and Costume Design Association
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• v.23 no.2
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• pp.147-153
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• 2021

Baekje patterned Pyojihwajomoonkeum is a fabric that expresses Baekje's unique culture possessed by Shosoin(正倉院) in Japan. Reflecting the close exchange relationship with the Chinese Southern Dynasties, these patterns are suitable as good examples to grasp the forms and atmosphere that prevailed during that era. Through the analysis of many pieces, it has been identified that the patterns were unique to Baekje. With an aim to ascertain and restore the original form of Pyojihwajomoonkeum, designs were proposed utilizing Pyojihwajomoonkeum as a form of storyteller clothing that fits the modern sense. Fabric was designed by continuously repeating the colors and patterns of Pyojihwajomoonkeum upward, downward, leftward, and rightward and woven with a Jacquard loom. The fabric woven was dried, processed, and used to make a total of four pieces of storyteller clothing consisting of men's wear, comprising a jeogori and pants, and women's wear comprising a jeogori and skirt. The top jacket was long enough that the hip is covered. It has wide sleeves and linear decorations were attached to the collar, lower edge of sleeve, and bottom hem. The pants are wide legged, the top is wide, and the bottom hem had linear decorations attached. What is the most important when using the original form of a traditional culture is processing the raw materials following cultural traditions to create value. Costumes of an era are the combination of individual elements and represent the culture of that era. Therefore, a consideration of the origin and prevailing ideas of the era must be considered. It is anticipated that this paper will serve as a basis for leading such a process, followed by studies on the utilization of the original form of Baekje culture.

• Journal of the Korean institute of surface engineering
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• v.54 no.1
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• pp.25-29
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• 2021

The fabrication of nanopore membrane by deposition of Al2O3 film using electron-beam evaporation, which is fast, cost-effective, and negligible dependency on substance material, is investigated for potential applications in water purification and sensors. The decreased nanopore diameter owing to increased wall thickness is observed when Al2O3 film is deposited on anodic aluminum oxide membrane at higher deposition rate, although the evaporation process is generally known to induce a directional film deposition leading to the negligible change of pore diameter and wall thickness. This behavior can be attributed to the collision of evaporated Al2O3 particles by the decreased mean free path at higher deposition rate condition, resulting in the accumulation of Al2O3 materials on both the surface and the edge of the wall. The reduction of nanopore diameter by Al2O3 film deposition can be applied to the nanopore membrane fabrication with sub-100 nm pore diameter.

• Archives of Craniofacial Surgery
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• v.23 no.5
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• pp.220-227
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• 2022

Background: Frontal sinus fractures are relatively rare. Their surgical management significantly differs depending on whether the posterior wall is invaded and the clinical features vary. A bicoronal incision or endoscopic approach can be used. However, the minimally invasive approach has been attracting attention, leading us to introduce a simple and effective surgical method using multiple-threaded Kirschner wires. Methods: All patients had isolated anterior wall fractures without nasofrontal duct impairment. The depth from the skin to the posterior wall was measured using computed tomography to prevent injury. The edge of the bone segment on the skin was marked, a threaded Kirschner wire was inserted into the center of the bone segment, and multiple Kirschner wires were gently reduced simultaneously. Results: Surgery was performed on 11 patients. Among them, seven patients required additional support for appropriate fracture reduction. Therefore, a periosteal elevator was used as an adjunct through a small sub-brow incision because the reduction was incomplete with the Kirschner wire alone. The reduction results were confirmed using facial bone computed tomography 1 to 3 days postoperatively. The follow-up period was 3 to 12 months. Conclusion: The patients had no complications and were satisfied with the surgical results. Here we demonstrated an easy and successful procedure to reduce a pure anterior wall frontal sinus fracture via non-invasive threaded Kirschner wire reduction.

• Journal of Integrative Natural Science
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• v.15 no.3
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• pp.131-136
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• 2022

Cell migration is essential for diverse cellular processes including wound healing, immune response, development, and cancer metastasis. Pi3-kinase (PI3K) is a key regulator for actin cytoskeleton and phosphorylates phosphatidylinositol (4,5)-diphosphate (PIP2) to phosphatidylinositol (3,4,5)-trisphosphate (PIP3). High levels of PIP3 by PI3Ks are associated with increased levels of F-actin and pseudopod extension at the leading edge of migrating cells such as neutrophils and Dictyostelium. LY294002 is a well-known PI3K specific inhibitor. Here, we investigated the effect of LY294002 on cell migration. First, we evaluated the appropriate concentration of dimethyl sulfoxide (DMSO) for using as a solvent for LY294002. DMSO is a highly polar organic reagent and one of the most common solvent for organic and inorganic chemicals. Cell morphology and cell migration were unaffected at the concentrations less than 0.1 % DMSO. Therefore, stock solution of LY294002 was prepared so that the final concentration of DMSO was 0.1 % or less when treated. When cells were treated with LY294002, cell migration was increased in a concentration-dependent manner. The maximum speed was detected in the presence of 30 µM LY294002. These results suggest that PI3Ks play a inhibitory role in regulating cell migration in our experimental conditions.

• Wind and Structures
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• v.34 no.1
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• pp.15-27
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• 2022

This work comes within the framework of the "Benchmark on the Aerodynamics of a Rectangular Cylinder" that investigates a rectangular cylinder of length-to-depth ratio equal to 5. The present study reports and discusses velocity fields acquired using planar Particle Image Velocitmetry for several angles of attack and Reynolds numbers. In particular, for a cylinder depth-based Reynolds number of 2 × 10⁴ and zero incidence angle, the flow features along the lateral (parallel to the freestream) upper and lower surfaces of the cylinder are reported. Using first and second order statistics of the velocity field, the main flow features are discussed, especially the size and location of the time-averaged flow structures and the distribution of the Reynolds stresses. The variation of the flow features with the incidence is also studied considering angles of attack up to 6°. It is shown that the time-averaged flow is fully detached for incidence higher than 2°. For an angle of attack of 0°, the effects of the Reynolds number varying between 5 × 10³ and 2 × 10⁴ are investigated looking at flow statistics. It is shown that the time-averaged location of the reattachment point and the shape and position of the time-averaged main vortex are mostly constant with the Reynolds number. However, the size of the inner region located below the time-averaged shear layer and just downstream the leading edge corner appears to be strongly dependent on the Reynolds number.

• Wind and Structures
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• v.34 no.5
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• pp.437-450
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• 2022

Vortex-induced vibration (VIV) is a significant concern when designing slender structures with square cross sections. VIV strongly depends on structural dynamics and flow states, which depend on the conditions of the approaching flow and shape of a structure. Therefore, the effects of the angle of attack on the coupling effects of VIV for a square cylinder are expected to be significant in practice. In this study, the aerodynamic forces for a fixed and elastically mounted square cylinder were measured using wind pressure tests. Aerodynamic forces on the stationary cylinder are firstly discussed by comparisons of variation of statistical aerodynamic force and wind pressure coefficient with wind angle of attack. The coupling effect between the aerodynamic forces and the motion of the oscillating square cylinder by VIV is subsequently investigated in detail at typical wind angels of attack with occurrence of three typical flow regimes, i.e., leading-edge separation, separation bubble (reattachment), and attached flow. The coupling effect are illustrated by discussing the onset of VIV, characteristics of aerodynamic forces during VIV, and interaction between motion and aerodynamic forces. The results demonstrate that flow states can be classified based on final separation points or the occurrence of reattachment. These states significantly influence coupling effects of the oscillating cylinder. Vibration enhances vortex shedding, which creates strong fluctuations in aerodynamic forces. However, differences in the lock-in range, aerodynamic force, and interaction process for angles of attack smaller and larger than the critical angle of attack revealed noteworthy characteristics in the VIV of a square cylinder.

• Journal of the Korean Society of Visualization
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• v.20 no.3
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• pp.94-101
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• 2022

The evaluation of the drag and lift as the aerodynamic performance of airfoils is essential. In addition, the analysis of the velocity and pressure fields is needed to support the physical mechanism of the force coefficients of the airfoil. Thus, the present study aims at establishing two different deep learning models to predict force coefficients and flow fields of the airfoil. One is the convolutional neural network (CNN) model to predict drag and lift coefficients of airfoil. Another is the Encoder-Decoder (ED) model to predict pressure distribution and velocity vector field. The images of airfoil section are applied as the input data of both models. Thus, the computational fluid dynamics (CFD) is adopted to form the dataset to training and test of both CNN models. The models are established by the convergence performance for the various hyperparameters. The prediction capability of the established CNN model and ED model is evaluated for the various NACA sections by comparing the true results obtained by the CFD, resulting in the high accurate prediction. It is noted that the predicted results near the leading edge, where the velocity has sharp gradient, reveal relatively lower accuracies. Therefore, the more and high resolved dataset are required to improve the highly nonlinear flow fields.