• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.283-292
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• 2007

A research projects is currently being conducted to develop a nonlinear finite element analysis methods for predicting the structural behavior of reinforced concrete frame structures, exposed to fire. As part of this, reinforced concrete frames subjected to fire loads were analyzed using the nonlinear finite-element program DIANA. Two numerical steps are incorporated in this program. The first step carries out the nonlinear transient heat flow analysis associated with fire and the second step predicts the structural behavior of reinforced concrete frames subjected to the thermal histories predicted by first step. The complex features of structural behavior in fire conditions, such as thermal expansion, plasticity, cracking or crushing, and material properties changing with temperature are considered. A concrete material model based on nonlinear fracture mechanics to take cracking into account and plasticity models for concrete in compression and reinforcement steel were used. The material and analytical models developed in this paper are verified against the experimental data on simple reinforced concrete beams. The changes in thermal parameters are discussed from the point of view of changes of structure and chemical composition due to the high temperature exposure. Although, this study considers codes standard fire for reinforced concrete frame, any other time-temperature relationship can be easily incorporated.

• Composites Research
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• v.33 no.2
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• pp.39-43
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• 2020

Recently, fabrication process of thermoplastic polyamide-based composites with recyclability as well as impact, chemical, and abrasion resistance have been widely studied. In particular, thermoplastic reactive resin transfer molding (TRTM) in which monomer with low viscosity is injected and in-situ polymerized inside mold has received a great attention, because thermoplastic melts are hard to impregnate fiber preform due to their very high viscosity. However, it is difficult to optimize the processing conditions because of high reactivity and sensitivity to external environments of the used monomer, ε-caprolactam. In this study, viscosity as an important process parameter in TRTM was measured during in-situ anionic polymerization of ε-caprolactam and the solutions for problems caused by high polymerization rate and sensitivity to moisture and oxygen were suggested. Reliability of the improved measurement technique was verified by comparing the viscosity behavior at various environmental conditions including humidity and atmosphere, and it is expected to be helpful for optimization of TRTM process.

• Fire Science and Engineering
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• v.29 no.1
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• pp.80-86
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• 2015

This study analyzed recent cases of ship fires explosions and investigated their problems and coping plans. Through analysis on the statistical figures, it was found that our nation's situations of maritime accidents by kind during the period of 2009~2013 showed the ratios of ship accidents caused by fires explosions was the highest in 2012 with 7.58% (55 cases) followed by year 2009 with 3.39% (34 cases), year 2010 with 3.39% (25 cases), year 2011 with 6.03% (57 cases) and year 2013 with 6.74% (43 cases), which indicates a steady increase in the number of ship accidents. Majority of reasons for ship fires explosions were lack of safety awareness. Since those accidents happen on the sea, fires, once they happen, tend to get serious due to absence of on board & nearby fire extinguishing facilities, public fire service's uneasy access to them and great influences of natural factors such as wind and etc. Ship fires explosions are special cases unlike what happens to general edifices. So, their coping plans should focus on preventive measures since the damages those cases bring about can be detrimental. For this reason, it's necessary to research precise evacuation plans, develop ship structure & materials reinforcing fire resistance to secure more time for evacuation and enhance people's safety awareness by implementing thorough safety training.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.1
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• pp.111-116
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• 2022

Recently, building structures tend to be super high-rise and large-scale with the development of concrete technology. When high-rise building is constructed of reinforced concrete structure, it has a disadvantage that its own weight increases. Light weight aggregate(LWA) was developed to compensate for these shortcomings. Manufacturing concrete using these light weight aggregates has the advantage of reducing the self weight of the reinforced concrete structure, but has a disadvantage in that the strength of the concrete is reduced. In this study, an experimental study was conducted to investigate the strength characteristics of hardened cement according to the presence or absence of surface coating of lightweight aggregates. As a result, in terms of compressive strength, the surface-coated lightweight aggregate exhibited higher strength than the uncoated lightweight aggregate. Also, it was considered that this is because the interfacial voids of the surface coated lightweight aggregate mixed cement hardened body were filled with blast furnace slag fine powder particles.

• Economic and Environmental Geology
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• v.15 no.2
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• pp.89-102
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• 1982

Several mines in Jeonnam produce the ores of having high SK number of refractoriness. Among those for 5 mines, this paper deals with the relationahip between SK number and mineral composition of the ore, and with the genesis of the deposits. 1. Byok-Song and Chon-Un Mine: Mineral compositions of the ores are chiastolite, chloritoid(monoclinic), kaolinite, sericite, diaspore, corundum, and quartz. The ores having SK number of 36 or 37, consist chiefly of chiastolite and diaspore and a little amount of kaolinite, sericite, corundum, chloritoid, and quartz. The ores having SK number of 33 or 34 consist of chloritoid, sericite, kaolinite, chiastolite, and diaspore. With increasing the amount of chloritoid and sericite, and decreasing the amount of diaspore and chiastolite, the SK number of the ores decreases. The deposit, originally high alumina-bearing shale of Chon-Un San formation, seems to be formed by contact metamorphism(forming of chiastolite), regional metamorphism(forming of monoclinic chloritoid), and hydrothermal replacement(forming of large crystal of diaspore veinlets). 2. Song-Sauk Mine: Mineral compositions of the ores are chiefly pyrophyllite and quartz and a little amount of kaolinite, dickite, diaspore, and pyrite. Many spherical inclusions containing in pyrophyllite deposits, consist chiefly of diaspore and kaolinite, The inclusions have the high SK number of 38. Amount of spherical inclusions is about 5 % to the whole pyrophyllite ores. The SK number of other pyrophyllite ore is less than 32. Quartz and pyrite are chief minerals lowering the SK number of the ore. The deposits have been formed by hydrothermal processes by replacing the siliceous tuff of Mesozoic age. Spherical inclusions consisting of diaspore and kaolinite, show the selective replacement of hydrothermal solutions to the materials of feldspar in tuff. 3. Seung-San Mine: Mineral compositions of the ores are chiefly kaolinite, dickite, diaspore, and quartz. But some part of the mine consists of alunite deposits. The ores having SK number of 35 or higher consist chiefly of kaolinite and diaspore and a little amount of quartz. With increasing the amount of quartz and decresing the amount of diaspore, the SK number of the ore decreases. The deposits have been formed by hydrothermal processes by replacing the siliceous tuff and quartz porphyry. 4. Wan-Do Mine: Mineral compositions of the ores are chiefly pyrophyllite and quartz. But some ore contains a little amount of diaspore, kaolinite, pyrite, and chloritoid. The ores having high SK number of 36 consist chiefly of diaspore and pyrophyllite. Pyrophyllite ore has a SK number of 32 or lower. Amount of quartz and pyrite decreases the SK number of ores in this mine. Rhyolite was replaced by the action of hydrothermal solutions forming the pyrophyllite deposits.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.79-90
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• 2007

Prototype of $800{\ell}$ vacuum web coater (Vic Mama) consisting of ion source with low energy less than 250 eV for high speed surface modification and 4 magnetron sputter cathodes was designed and constructed. Its performance was evaluated through fabricating the adhesiveless flexible copper clad laminate (FCCL). Pumping speed was monitored in both upper noncoating zone pumped down by 2 turbo pumps with 2000 l/sec pumping speed and lower surface modification and sputter zone vacuumed by turbo pumps with 450 1/sec and 1300 1/sec pumping speed respectively. Ion current density, plasma density, and uniformity of ion beam current were measured using Faraday cup and the distribution of magnetic field and erosion efficiency of sputter target were also investigated. With the irradiation of ion beams on polyimide (Kapton-E, $38{\mu}m$) at different fluences, the change of wetting angle of the deionized water to polyimide surface and those of surface chemical bonding were analyzed by wetting anglometer and x-ray photoelectron spectroscopy. After investigating the deposition rate of Ni-Cr tie layer and Cu layer was investigated with the variations of roll speed and input power to sputter cathode. FCCL fabricated by sputter and electrodeposition method and characterized in terms of the peel strength, thermal and chemical stability.

• Applied Microscopy
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• v.23 no.1
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• pp.1-14
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• 1993

The present study was carried out to analyze the evidence of membrane recycling, and the regulation of cellular transport by dynamic changes in apical membrane area that functionally interacts with the number of cytoplasmic vesicles. Under scanning electron micrographs, turtle bladder mucosa contain three main type of cells; granular cells and carbonic anhydrase (CA)-rich cells, deviding into a and b type of epithelial cell. The granular cell is the majority cell type of the mucosa comprising 80% of the total cell number. The remaining 20% of the cells are characteristically rich in carbonic anhydrase. Uptake of HRP was detected in the most vacuoles or tubulovesicles in both type of CA-rich cells in the turtle bladder, indicating that the part of plasma membrane was internalized in the apical cytoplasmic vacuoles. It seems quite likely that CA-rich cells possess intracellular vesicles carrying proton pumps which are recycling back to the apical plasma membrane. In turtle bladder, the granular cells actively secrete large quantities of mucin and other proteins by an exocytotic mechanism in an apparently constitutive fashion. The possibility that bladder epithelial cells secrete mucin via a regulated secretory pathway has not been rigorously examined and much is still to be determined about these issues from this cell type.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.81-88
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• 2005

The fly ash has been widely used in the latest to complement the performance and economical efficiency of the concrete which uses only a normal portland cement, the pulp ash gained through the incineration of paper sludge is possible to be used as the material of concrete because it contains the properties similar to the previous fly ash in ingredients and physical characteristics. Therefore, this research has tested physical characteristics by replacing 20% of fly ash used with the paper ash to solve the problem which lowers the early strength caused when the fly ash was used. As a result, it showed that the fluidity becomes lower and the compressive strength becomes increased by using paper ash. In addition, after mixing the paper ash with the fly ash, it showed that time and heating amount of the 2nd peak of the minor heat of hydration affecting the revelation of strength was equivalent to the combination for normal portland cement, and also indicated that the compressive strength for 3 days is superior to the combination of the fly ash. Therefore, if the paper ash having a regular fineness is used, it was effective in improving the early strength of concrete used the fly ash.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.401-412
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• 2020

This study analyzed the causes of warehouse fires using a creative problem-solving technique called TRIZ. It identified preventive measures by applying 4M. The results are as follows. First, this study examined the inconsistency among the causes of warehouse fires using TRIZ. Second, it analyzed human factors and fire prevention measures in warehouses such as safety standards for managers, and methods for the promotion of safety consciousness among workers, and for the reinforcement of construction technology for sandwich panel workers. Third, it identified the mechanical and facility factors and fire prevention measures in warehouses such as safety facilities, the expanded installation of safety devices, the adoption and development of fire suppression equipment, and the deployment of methods to improve the fire resistance of sandwich panels. Fourth, it presented working and environmental factors and fire prevention measures in warehouses such as the tightening of safety precautions and the supervision of working methods, and setting fire partitions both in loading places and based on performance-based design. Finally, it proposed managerial factors and fire prevention measures in warehouses such as specific targeting for firefighting with low fire hazards, reviewing the material quality regulations of non-combustible or higher for sandwich panels in the specific target of firefighting that cannot apply fire safety standards, installing sprinklers in cold storage, and mandating the installation of automated facilities with retroactive application regardless of the floor area in the warehouse with a sandwich panel structure.

• Composites Research
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• v.23 no.4
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• pp.44-51
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• 2010

Recently, to solve the problems associated with the neutralization and corrosion of reinforced concrete compression members, the structural configurations such as CFFT (Concrete Filled GFRP Tube) and RCFFT (Reinforced Concrete Filled GFRR Tube) have been developed and applied to main members of civil engineering structure. These members can increase structural performance in terms of structural stability, ductility as well as chemical resistance compared with conventional concrete structural members. Many researches in numerous institutions to predict the load carrying capacity of the concrete compression member strengthened with FRP materials have been conducted and they have been suggested an equation for the prediction of the load carrying capacity of the members. Through the review of the research results, it was found that their results are similar each other. Moreover, it was also found that the results are not directly applicable to our specimens since the results are largely depended upon the member configurations. Also, since the accurate design criteria for the RC members strengthened with FRP such as RCFFT have not been established properly, relevant theoretical and experimental investigations must be conducted for the application to the practical structures. In this study, structural behavior of RCFFT was evaluated through compressive and quasi-static flexural tests in order to formulate design criteria for the structural design. In addition, the RCFFT members were also investigated to examine their confinement effect and the equations capable of estimating the compressive ultimate strength and flexural stiffness of the RCFFT members were proposed.