• Journal of the Korean institute of surface engineering
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• v.52 no.1
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• pp.37-42
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• 2019

Electrodeposited zinc layer is widely used as a sacrificial anode for a corrosion protection of steel. In this study, we modified the surface of electrodeposited zinc to have a hydrophobicity, which shows various advanced functionalities, such as anti-corrosion, anti-biofouling, anti-icing and self-cleaning, due to its repellency to liquids. Superhydrophobicity was realized on electrodeposited zinc layer with a hydrothermal treatment, creating nanostructures on the surface, and following Teflon coating. The superhydrophobic surface shows a great repellency to water with high surface tension, while liquid droplets with low surface tension easily adhered on the superhydrophobic surface. However, immiscible lubricant-impregnated superhydrophobic surface shows a great repellency to various liquids, regardless of their surface tension. Therefore, it is expected that the lubricant-impregnated surface can be an alternative of superhydrophobic surface, which have a drawback for some liquids with a low surface tension.

• Earthquakes and Structures
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• v.23 no.6
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• pp.517-526
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• 2022

Previous studies have shown that pile-soil interactions have significant influences on the isolation efficiency of an isolated structure. However, most of the existing tests were carried out using a 1-g shaking table, which cannot reproduce the soil stresses resulting in distortion of the simulated pile-soil interactions. In this study, a centrifuge shaking table modelling of the seismic responses of a friction pendulum bearing isolated structure with a pile foundation under earthquakes were conducted. The pile foundation structure was designed and constructed with a scale factor of 1:100. Two layers of the foundation soil, i.e., the bottom layer was made of plaster and the upper layer was normal soil, were carefully prepared to meet the similitude requirement. Seismic responses, including strains, displacement, acceleration, and soil pressure were collected. The settlement of the soil, sliding of the isolator, dynamic amplification factor and bending moment of the piles were analysed to reveal the influence of the soil structure interaction on the seismic performance of the structure. It is found that the soil rotates significantly under earthquake motions and the peak rotation is about 0.021 degree under 24.0 g motions. The isolator cannot return to the initial position after the tests because of the unrecoverable deformation of the soil and the friction between the curved surface of the slider and the concave plate.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.424-430
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• 2021

The purpose of this study is to analyse the characteristics and spreading laws of parameters such as fire smoke, concentration of CO, visibility, and temperature at fire scene in high-rise residential buildings under the different conditions of fire doors and automatic fire extinguishing systems. Using Pyrosim to simulate diverse fire scenes in a high-rise apartment with corridors, to analyze the changes in those parameters. The results show that when a fire occurs, closing the fire-fighting corridor will increase the smoke temperature and concentration of CO in the stairwell, and reduce the height and visibility of the smoke layer; the automatic fire extinguishing system effectively suppresses the increase in the temperature of the fire smoke and the sedimentation of the smoke layer. Reasonable setting and operation of the automatic fire extinguishing system could effectively inhibit the spread of fire. Although closing fire corridor can slow down the direct upward spread of smoke through the corridor, it will force the fire smoke into the stairwell, which will seriously affect evacuation through the stairs. Therefore, in order to reduce risks, it is forbidden to close the fire doors of the firefighting corridor and stacking combustible materials in the corridor, Also, intensifying inspections and ensuring the normal operation of the automatic fire extinguishing system are indispensable. Based on the research results, the significance of installing fire-fighting facilities in the construction of high-rise apartments was discussed and proved.

• Journal of Korean Association for Spatial Structures
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• v.23 no.3
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• pp.87-94
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• 2023

Chloride is one of the most common threats to reinforced concrete (RC) durability. Alkaline environment of concrete makes a passive layer on the surface of reinforcement bars that prevents the bar from corrosion. However, when the chloride concentration amount at the reinforcement bar reaches a certain level, deterioration of the passive protection layer occurs, causing corrosion and ultimately reducing the structure's safety and durability. Therefore, understanding the chloride diffusion and its prediction are important to evaluate the safety and durability of RC structure. In this study, the chloride diffusion coefficient is predicted by machine learning techniques. Various machine learning techniques such as multiple linear regression, decision tree, random forest, support vector machine, artificial neural networks, extreme gradient boosting annd k-nearest neighbor were used and accuracy of there models were compared. In order to evaluate the accuracy, root mean square error (RMSE), mean square error (MSE), mean absolute error (MAE) and coefficient of determination (R2) were used as prediction performance indices. The k-fold cross-validation procedure was used to estimate the performance of machine learning models when making predictions on data not used during training. Grid search was applied to hyperparameter optimization. It has been shown from numerical simulation that ensemble learning methods such as random forest and extreme gradient boosting successfully predicted the chloride diffusion coefficient and artificial neural networks also provided accurate result.

• Progress in Superconductivity and Cryogenics
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• v.8 no.3
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• pp.23-26
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• 2006

For mechanical and electrical stability and environment protection. Cu and stainless steel stabilizers are laminated to a Ag layer to produce a composite neutral-axis(N-A) architecture in which the YBCO layer is centered between the oxide buffered metallic substrate and stabilizer strip lamination. This architecture allows the wire to meet operational requirements including stresses at cryogenic temperature. winding tensions as well as mechanical bending requirements including thermal and electrical stability under fault current conditions. We have experimentally studied mechanical properties of the laminated stainless steel and Cu stabilizers on YBCO coated conductors. We have laminated YBCO coated conductors by continuous dipping soldering process. We have investigated lamination interface between solder and stabilizer of the YBCO coated conductor. We evaluated bonding properties. tensile / shear bonding strength. and peeling strength laminated YBCO coated conductors.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.9-12
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• 2007

In this study. we searched for the mechanical and electrical properties of laminated coated conductors with stabilizer tape. Stabilizer tape plays a role for mechanical and electrical stability and environmental protection. Cu material stabilizer was laminated to Ag capping layer on SmBCO conductor layer. This architecture allows the wire to meet operational requirements including the stressless at cryogenic temperature and winding tension as well as mechanical bending requirements including thermal and electrical stability under fault current conditions. First, we have experimentally studied mechanical bonding properties of the laminated Cu stabilizers on SmBCO coated conductors. We have laminated SmBCO coated conductors by continuous dipping soldering process, Second, we have investigated electrical properties of the SmBCO coated conductors with stabilizer lamination. We evaluated bonding properties, peeling strength and critical current for laminated SmBCO coated conductors with Cu stabilizers.

• Earthquakes and Structures
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• v.27 no.1
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• pp.57-67
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• 2024

To assess the seismic performance of Plate-Shell Integrated Concrete Liquid-Storage Structure (PSICLSS), a scaled test model was constructed. This model incorporated a hybrid isolation system, which combined shape memory alloy (SMA), lead-cored rubber isolation bearing (LRB) and sliding isolation bearing (SB). By conducting shaking table test, the dynamic responses of both non-isolated and hybrid-isolated PSICLSS were analyzed. The results show that the hybrid isolation system can effectively reduce the acceleration and displacement responses of the structure. However, it also results in an increase in local hydrodynamic pressure and liquid sloshing height. Under extreme earthquake action, the displacement of isolation layer is small. When vertical ground motion is taken into account, the shock absorption rate of horizontal acceleration decreases. The peak hydrodynamic pressure increases significantly, and the peak hydrodynamic pressure position also changes. The maximum displacement of isolation layer increases, the residual displacement decreases.

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.187-197
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• 1987

Bacteria and fungi antagonistic to Fusarium oxysporum f. sp. cucumerinum Owen were effectively isolated with each of modified Triple Layer Agar (TLA) technique from rhizosphere soil where cucumber had been grown healthily in plastic film house. Three predominant bacterial isolates selected were identified as Pseudomonas fluorescens, and P. putida, Serratia sp. and three fungal isolates were Gliocladium sp. Trichoderma harzianum, and T. viride. Antagonistic bacteria inhibited $26-45\%$ of germination and $41-56\%$ of germ tube elongation of microconidia of F. oxysporum f. sp. cucumerinum on Water Agar (WA). P. fluorescens was the strongest inhibitor. Several my co parasitisms were observed on dual culture of WA between antagonistic fungi and F. oxysporum f. sp. cucumerinum such as coiling, penetration, overgrowing, and lysis. Mycelial lysis of the pathogen was the most severe at pH 4.6, followed by 3.6, 5.6 and 6.6 of the medium in decreasing order. At pH 6.6, mycelia of the pathogen were not conspicuously damaged, however, the antagonistic fungi formed abundant chlamydospores especially Gliocladium sp. T. harzianum revealed the most excellent antagonism in vitro.

• Journal of radiological science and technology
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• v.41 no.2
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• pp.157-162
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• 2018

This study is a search for radiation protection effects of radiation exposure on the organogenic period during the prenatal period, which is known to be the most likely to have congenital malformations by radiation exposure. To study the radiation protection for the mixture of selenium that is strong antioxidant and folic acid that is essential vitamin for DNA synthesis, 2 Gy of radiation was irradiated to pregnant female rats. then, after 14 days of fetal birth, observing blood components, SOD(Superoxide Dismutase), histological changes and external malformations. There was a significant protective effect to reduce blood cell damage(p<0.05) in the irradiation group after selenium and folic acid mixture were administered than irradiation group, and the activation of SOD which is antioxidant enzymes was increased. In addition, confirmed the effect of suppressing the expression of apoptosis of small intestinal cells and the reduction of cerebral cortex layer reduction by radiation. thus, it was confirmed that the congenital malformations were reduced as a result of these protective effects. Based on these results, selenium and folic acid mixture may reduce the incidence of congenital malformations, and it will reduce the damage of the fetus caused by the exposure of the organogenic period due to accidents.

• Journal of Information Display
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• v.9 no.4
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• pp.30-34
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• 2008

Field emitter arrays (FEAs) were developed using carbon nanotubes (CNTs) as electron emission sources. The CNTs were grown using a selective-positioning technique with a resist-protection layer. The light emission properties were studied through the electron emission of the CNTs on patterned islands, which were modulated with island diameter and spacing. The electron emission of CNT arrays with $5{\mu}m$ diameters and $10{\mu}m$ heights increased with increased spacing (from $10{\mu}m$ to $40{\mu}m$). The electron emission current of the $40-{\mu}m$-island-spacing sample showed a current density of 1.33 mA/$cm^2$ at E = 11 V/${\mu}m$, and a turn-on field of 7 V/${\mu}m$ at $1{\mu}A$ emission current. Uniform electron emission current and light emission were achieved with $40{\mu}m$ island spacing and $5{\mu}m$ island diameter.