• Journal of Ginseng Research
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• v.15 no.3
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• pp.167-170
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• 1991

Radiation protective fraction was Isolated and partially purified from Korean white ginseng. The effect of the fraction was studied on the cell survival of W-damaged CHO-Kl cells. As a result, it was found that the fraction increased the survival rate of damaged cells significantly within the dose range of which cytotoxicity did not appear This fraction was separated into two parts by adding butanol, namely the precipitated protein component and the butanol extract. Damaged cells were treated with each of these components and their survival rates were measured. The protein component demonstrated significant increase in the survival rates, while the butanol extract showed no such increment. These results suggest that the radiation protective effect of the ginseng fraction is originated from the butanol-precipitated protein component, not from the butanol-soluble compounds.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.243-244
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• 2021

In this study, we develop diagnostic technology for damage depth of fire-damaged concrete and propose methods for damage caused by fire by drying damaged concrete after immersion. As a result of the test, the damaged depth was clearly found when evaluating the depth of impurities caused by fire in a drying method after water had permeated, and it could be verified using thermogravimetric analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.343-346
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• 2003

Confirmation of a damage degree and repair about a damage part are very hard for an underwater structure. And quality control of a construction is very complicated even if repair work is carried out on a damaged structure because repair work is carried out in water. If repair work is carried out while a defect part of the structure which there is in water keeps dry state, a efficient of repair is maximized. However, as for the repair technology about an underwater structure, a systematic researcher is not enough because of the environmental trouble. And, as for the effect about repair method to be applied to a currently underwater structure, it is not certainly proved. In this study The repair work of an underwater structure damaged applied the method that used a fiber panel form work. And a efficient of structure repaired was evaluated.

• Corrosion Science and Technology
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• v.18 no.5
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• pp.190-195
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• 2019

SA508 low-alloy steel for a reactor vessel was exposed to primary water in a pressurized water reactor (PWR) plant because the cladding layer of type 309 stainless steel for the RPV was removed, due to an accident in which the detachment of the thermal sleeve occurred. The major advantage of the electrochemical deposition (ECD) Ni plating technique is that the reactor pressure vessel can be repaired without significant thermal effects, and Ni has solid corrosion resistance that can withstand boric acid. The corrosion rate assessment of the damaged part was performed, and its trend was analyzed. Essential variables of the Ni plating for repair of the damaged part were derived. These conditions are applicable variables for the repair plating device, and have been carefully adjusted using the repair plating device. The process for establishing ASME technical standards called Code Case N-840 is described. The process of developing Ni-plating devices, and the electroplating procedure specification (EPS) are described.

• Journal of the Korea Institute of Building Construction
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• v.24 no.3
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• pp.297-308
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• 2024

This study presents a novel approach for evaluating fire-induced damage depth in concrete. The methodology leverages the principle that exposure to high temperatures causes internal expansion within concrete, leading to increased voids and microcracks in the damaged zones. This heightened porosity results in greater absorption rates compared to undamaged areas. By immersing fire-damaged concrete samples in water and subsequently monitoring the drying process, the depth of damage can be assessed. Differences in drying rates and color variations between damaged and undamaged areas serve as visual indicators for determining the extent of the damage. Experimental results from this water immersion method revealed damage depths of 38.7mm and 37.5mm for two different concrete mixtures. These measurements notably surpass the damage depths estimated using traditional phenolphthalein-based methods. This discrepancy suggests that utilizing the absorption rate principle, which is directly linked to the physical changes caused by thermal expansion, offers a more accurate and sensitive assessment of fire damage depth compared to methods relying solely on the presence of Portlandite for colorimetric indication.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.57-62
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• 2012

The purpose of this paper is to find dangerous factors of a water purifier when water leaks due to inappropriate use and analyze the patterns of damaged parts in order to provide data for the examination of the cause of the problem. If the water purifier is inspected and managed by a non-specialist, when the FLC(Float Level Controller) at the top is inclined, water leakage may occur to the water purifier. The leaked water flows onto the cables and hoses and enters the thermostat terminal, heater, PCB, power supply connection connector, etc., becoming a dangerous factor that may cause a system failure, fire, etc. Due to the water that entered the input terminal, low noise and white smoke were generated at first. However, the flame gradually propagated due to the continuous inflow of moisture. It was found that when moisture reached the PCB, a carbonized conductive path was formed at the varistor terminal, input terminal, semiconductor device terminal, etc., and the flame became larger, which might result in a fire. From the metal microscope analysis of a damaged condenser terminal, it was found that the amorphous structure unique to copper cable disappeared, and voids, boundary surface and disorderly fine particles occurred. Also, in the case of the connector into which moisture penetrated, fusion and deformation occurred at the cable connection clips. The result of analysis of the power supply cable connector using a thermal image camera showed that most of the heat was generated from the cable connection clips and the temperature at the connection center was normal.

• Steel and Composite Structures
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• v.21 no.2
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• pp.411-427
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• 2016

While the cyclic behaviour of fiber-reinforced polymer (FRP)-confined columns is studied rather extensively, the cyclic response especially the energy dissipation of FRP-confined damaged and undamaged square RC columns is not yet fully understood. In this paper, an experimental and numerical investigation was conducted to study the cyclic behavior of two different types of Carbon FRP (CFRP)-confined square RC columns: strengthened and repaired. The main variables investigated are initial damage, confinement of CFRP, longitudinal steel reinforcement ratio. The experimental results show that lower initial damage, added confinement with CFRP and longitudinal reinforcement enhance the ductility, energy dissipation capacity and strength of the columns, decrease the stiffness and strength degradation rates of all CFRP-confined square RC columns. Two hysteretic constitutive models were developed for confined damaged and undamaged concrete and cast into the non-linear beam-column fiber-based models in the software Open System for Earthquake Engineering Simulation (OpenSees) to analyze the cyclic behavior of CFRP-confined damaged and undamaged columns. The results of the numerical models are in good agreement with the experiments.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.1
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• pp.50-59
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• 2000

This paper presents a brief outline of dynamic stability of a damaged ship at final stage of flooding in rough beam wind and waves. One degree-of-freedom, roll equation is adopted with effects of flooding water and external forces due to wind and waves, but without effect of sloshing. We discuss the dynamic stability of the damaged ship in terms of capsizing probability based on risk analysis, the method of which was firstly proposed by Umeda et al.[6] to high speed craft in intact condition. As a result, we can evaluate the dynamic stability of the damaged ship in probabilistic manner according to sea state, operating condition and damage situation.

• Corrosion Science and Technology
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• v.19 no.6
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• pp.310-317
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• 2020

This study investigated the damage to the specimen due to liquid droplet impingement erosion corrosion, which improved the corrosion resistance and durability via hard anodization of 5083-H321 aluminum alloy, which is widely used for small ships and marine structures. The experiment combined liquid droplet impingement erosion and electrochemical equipment with the flow rates in natural seawater solution. Subsequently, Tafel extrapolation of polarization curves was performed to evaluate damage due to the liquid droplet impingement erosion corrosion. The damaged surface was observed using a 3D microscope and a scanning electron microscope. The degree of pitting damage was measured using the Image J program, and the surface hardness was measured using the micro-Vickers hardness tester. The corrosion current density, area, depth, and ratio of the damaged areas increased with the increase in flow rate. The grain size of the damaged area at a flow rate of 20 m s-1 showed fewer and minor differences in height, and a smooth curved shape. The hardness of the damaged surface tended to decrease with increase in flow rate.

• Structural Engineering and Mechanics
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• v.84 no.1
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• pp.49-61
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• 2022

This paper presents an experimental investigation into the effectiveness of using carbon fibre reinforced polymer (CFRP) and steel plates to repair damaged reinforced concrete (RC) beams with circular web openings at shear zones. It highlights the effectiveness of externally bonded CFRP and steel plates in repairing damaged RC beams by analysing the repaired beams'load capacity, deflection, strain, and failure mode. For the experiment, a total of five beams were used, with one solid beam as a control beam and the other four beams having an opening near the shear zone. Two beams with openings were repaired using inclined and vertical configuration CFRP plates, and the other two were repaired using inclined and vertical configuration steel plates. The results confirm the effectiveness of CFRP and steel plates for repairing damaged RC beams with circular openings. The CFRP and steel plates significantly increase ultimate capacity and reduce deflection under the openings. The inclined configuration of both CFRP and steel plates was more effective than the vertical configuration. Using an inclined configuration not only increases the ultimate capacity of the beams but also changes the mode of failure from shear to flexural.