• Fire Science and Engineering
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• v.32 no.3
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• pp.14-18
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• 2018

The earlier studies on the fire resistance performance of woods used as building materials have focused on confirming combustion characteristics of fire retardant or flame resistant treated wood. In this paper, to confirm internal temperature changes closely related to pyrolysis of woods exposed to the flame, heating experiments were conducted in a heating furnace according to the standard heating temperature curves after Douglas-fir, which is widely used as structural materials, was treated with a flame resistant solution and flame retardant paint. As a result of the experiment, it was confirmed that the thermal diffusion inside the wood has decreased when the wood was treated with the flame resistant solution. However, in high temperature, the flame resistant effect could not be expected due to the peeling of the coating in the case of the flame resistant paint treated wood. Therefore, it can be considered that it is more effective to use the flame resistant solution which penetrates in to the inside of the wood than flame resistant paint which forms the coating on the surface of the wood in order to enhance the flame resistance effect on the thick wood.

• Advances in concrete construction
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• v.8 no.3
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• pp.173-185
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• 2019

This article presents a comparative study of the effect of steel layouts on the seismic behavior of transition steel-concrete composite connections, both experimental and analytical investigations of concrete filled steel tube-reinforced concrete (CFST-RC) and steel reinforecd concrete-reinforced concrete (SRC-RC) structures were conducted. The steel-concrete composite connections were subjected to combined constant axial load and lateral cyclic displacements. Tests were carried out on four full-scale connections extracted from a real project engineering with different levels of axial force. The effect of steel layouts on the mechanical behavior of the transition connections was evaluated by failure modes, hysteretic behavior, backbone curves, displacement ductility, energy dissipation capacity and stiffness degradation. Test results showed that different steel layouts led to significantly different failure modes. For CFST-RC transition specimens, the circular cracks of the concrete at the RC column base was followed by steel yielding at the bottom of the CFST column. While uncoordinated deformation could be observed between SRC and RC columns in SRC-RC transition specimens, the crushing and peeling damage of unconfined concrete at the SRC column base was more serious. The existences of I-shape steel and steel tube avoided the pinching phenomenon on the hysteresis curve, which was different from the hysteresis curve of the general reinforced concrete column. The hysteresis loops were spindle-shaped, indicating excellent seismic performance for these transition composite connections. The average values of equivalent viscous damping coefficients of the four specimens are 0.123, 0.186 and 0.304 corresponding to the yielding point, peak point and ultimate point, respectively. Those values demonstrate that the transition steel-concrete composite connections have great energy dissipating capacity. Based on the experimental research, a high-fidelity ABAQUS model was established to further study the influence of concrete strength, steel grade and longitudinal reinforcement ratio on the mechanical behavior of transition composite connections.

• Journal of the Society of Disaster Information
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• v.20 no.2
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• pp.390-397
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• 2024

Purpose: In this study, PCM was used to give thermal performance to concrete and analyze its effect on durability to prevent disasters that may occur in concrete when exposed to hot and cold environments. Method: After preparing concrete specimens containing 10, 30, and 50% of the two types of PCMs compared to the cement volume, the pore volume, freeze melting resistance, and scaling resistance were evaluated. Result: Regardless of the type, when PCM powder was mixed with concrete, the amount of pores decreased, and when 10% and 30% were mixed, the freeze-melting resistance was also improved. It was also confirmed that the higher the mixing amount, the better the scaling resistance. Conclusion: When mixing powdered PCM into concrete, it is believed that durability can be improved to a certain level by the filling effect, and additional various studies should be supported for actual field application.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.4
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• pp.413-420
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• 2016

Hydroxy acid has been used to enhance anti-aging and skin moisturization by peeling effect on the skin stratum corneum, and thus it has been widely used in topical products and cosmetic products. Among them, the effect that appears most effectively in a short period of time has been reported to be effected by the pH of the cosmetic formulations. However, there are many difficulties in use due to irritation caused by pH and concerns about side effects. The purpose of this study was to evaluate the effect of applying cosmetics with (1) varying concentrations, (2) types and (3) pH of hydroxy acid on human skin. 22 healthy adults were stained with DHA (dihydroxyacetone) and DC (dansyl chloride) on the forearm, and the skin exfoliation effect was measured after application of the test products. (1) The application of GA (glycolic acid) increased the desquamation by concentration dependent. (2) the test product prepared with neutral pH showed no exfoliation effect. In contrast, SA (salicylic acid) showed a statistically significant exfoliation effect at both acidic pH and neutral pH. (3) The neutral pH SA showed excellent exfoliation effect on bot DHA and DC stained stratum corneum. These results suggest that it is possible to manufacture safe cosmetics without damaging the skin barrier, providing an opportunity to use cosmetics that are expected to exfoliate to people, whose skin is sensitive to pH.

• Korean Journal of Medicinal Crop Science
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• v.17 no.4
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• pp.233-237
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• 2009

Astragalus membranaceus has a long history of medicinal use in Chinese herbal medicine. It has been shown to have immunostimulant, tonic, antioxidant, antiperspirant, diuretic, anti-diabetic, expectorant properties, and a supplementary medicine during cancer therapy. In this study, we investigated the effect of anti-oxidation of Astragalus membranaceus root extract. The anti-oxidative activities of water, 80% methanol, and 100% methanol extracts from Astragalus membranaceus were analyzed by DPPH free radical scavenging activity, Superoxide dismutase-like activity, reducing power, and crude ash. The water extract demonstrated to be more effective than methanol extract for a DPPH radicals scavenging activities and reducing power. Superoxide dismutase-like activity showed higher efficiency in 80% methanol extract. Our results indicate that Astragalus membranaceus extracts could be used as a source of antioxidant ingredients in the food industry.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.557-566
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• 2001

Composite slab with deckplate needs sufficient bond strength between deckplate and concrete to conduct composite behavior Composite slab can transfer the shear by either chemical adhesion interface interlock, or active friction. There are several way of mechanical shear connection in composite slab. that is embossments shear connector shape of deckplate etc. Effect of mechanical interaction is deped on shape of deckplate which is to prevent peeling between deckplate and concrete and an amount of shear connector. The behavior and strength of the connection between the decking and the concrete slab due to embossments and end anchorage may be estimated using the push-off tests described in this paper We proposed the equation of shear bond strength in the composite slab It will be use to design by basic data in composite slab.

• Journal of Powder Materials
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• v.22 no.4
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• pp.271-277
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• 2015

As wrought stainless steel, sintered stainless steel (STS) has excellent high-temperature anti-corrosion even at high temperature of $800^{\circ}C$ and exhibit corrosion resistance in air. The oxidation behavior and oxidation mechanism of the sintered 316L stainless was reported at the high temperature in our previous study. In this study, the effects of additives on high-temperature corrosion resistances were investigated above $800^{\circ}C$ at the various oxides ($SiO_2$, $Al_2O_3$, MgO and $Y_2O_3$) added STS respectively as an oxidation inhibitor. The morphology of the oxide layers were observed by SEM and the oxides phase and composition were confirmed by XRD and EDX. As a result, the weight of STS 316L sintered body increased sharply at $1000^{\circ}C$ and the relative density of specimen decreased as metallic oxide addition increased. Compared with STS 316L sintered parts, weight change ratio corresponding to different oxidation time at $900^{\circ}C$ and $1000^{\circ}C$, decreased gradually with the addition of metallic oxide. The best corrosion resistance properties of STS could be improved in case of using $Y_2O_3$. The oxidation rate was diminished dramatically by suppression the peeling on oxide layers at $Y_2O_3$ added sintered stainless steel.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.1-9
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• 2017

Numerical computations are performed to investigate the effect of pintle stroke on the performance of an internal pintle thruster. Results show that the thrust control ratio was less than 2% and the aerodynamic load ratio was 22% as the pintle stroke increased. The flow past the nozzle throat rapidly expanding because of the shape of the pintle, and a shock wave was generated. Particularly, at the pintle stroke distance of 4 and 5 mm, the shock wave hit the wall of the nozzle, results in peeling bubbles. Depending on the altitude, the thrust increased and the aerodynamic load decreased, but the difference was as small as 1.5%. In the presence of the bore, the reduction of the pintle tip area resulted in a decrease in aerodynamic load.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.43-48
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• 2022

Effect of temperature/humidity (T/H) treatment conditions on the peel strength of screen-printed Ag/polyimide (PI) structures was evaluated by peeling PI films in 90° peel test. Initial peel strength was 25.99±1.47 gf/mm, and then decreased to 6.05±0.54 gf/mm after 500 h at 85℃/85% relative humidity T/H condition. And, the peeled locus was changed from Ag/PI interface to shallow cohesive inside PI near interface. X-ray photoelectron spectroscopy analysis on the peeled surfaces showed that the long-term moisture penetration into the Ag/PI interface during T/H treatment led to hydrolytic degradation of PI to form weak boundary layer inside PI near Ag/PI interface, which are responsible for large decrease in peel strength.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.873-880
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• 2008

When checking the state of deterioration or damage structures, regular visual inspection has very important role. At this point, a visual inspection is performed mainly by sketch or photography with a camera of inspectors. If that happens, it takes a lot of effort and time to inspect appearance damages. The purpose of this study is to develop the automatic recognition system for a more efficient and effective inspection of appearance damages. In the process, the image processing technology and the data management & analysis system for damage recognition are mainly developed and applied. This automatic recognition system enables inspectors or clients to obtain correct data that can recognize a damage, such as, crack, water leakage, efflorescence, delamination (peeling), spalling, etc. In addition, this study takes aim at the effect of secure safety, functional maintenance and extension of design lifetime according to build up continuous and systematic data management system.