• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.149-150
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• 2020

Granting self-sensing performance in a building is an important performance to ensure the degree of damage and safety of the building. Since the current research is being conducted in the state before deterioration loss occurs, it is necessary to confirm whether the self-sensing performance is maintained even in the damaged conductive cement composite. As part of the study, electrical resistance characteristics were analyzed in conductive cement composites in which freeze-thawing and chemical corrosion occurred. As a result, it was found that the change in electrical resistance value due to freeze-thawing was not as large as 1%, and chemical corrosion occurred. It was found that the change in electrical resistance value of the tested specimen increased by about 10%.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.89-92
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• 1995

For the development of lilght weight cement concrete with high durability, this study used perlite and paper sludge ash by the light weight material, and polypropylene fiber by the reinforcment, and poly-acrylic ester emulsion by the matrix improvement. According to the increasing mixture ratio of fiber and use of polymer, the light weight polypropylene fiber reinforced polymer cement ratio of fiber and use of polymer, the light weight polypropylene fiber reinforced polymer cement concrete were showed high resistance for frost damage.

• Asian-Australasian Journal of Animal Sciences
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• 제19권9호
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• pp.1335-1341
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• 2006

We selected a Lactobacillus spp. from Korean healthy infant feces based upon their antioxidant activity. This strain was identified as Lactobacillus gasseri by 16S rDNA sequencing, and named Lactobacillus gasseri NLRI-312. In the present study, we investigate the protective effect of this strain on the $H_2O_2$ induced damage to cellular membrane lipid and DNA in Jurkat cells. To estimate the extent of cellular lipid peroxidation inhibition, MDA (malondialdehyde) was measured, and DNA damage was tested by the comet assay. We also examined probiotic properties including tolerance to acid and bile, antibiotic resistance. From the results obtained, the supplementation of Jurkat cells with NLRI-312 decreased in DNA damage, while no effect was shown on MDA decrease. In probiotic properties, this strain was resistance to both acid and bile, showed considerably higher survival when incubated in pH 2 or 1% bile salts (w/v). We concluded that the NLRI-312 could be used as potential probiotic bacteria, with the effect of reducing DNA damage induced by $H_2O_2$.

• 한국안전학회지
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• 제30권3호
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• pp.7-12
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• 2015

CFRP composites are used as primary structural members in various industrial fields because their specific strength and specific stiffness are excellent in comparison to conventional metals. Their usage is expanding to high added-value industrial fields because they are more than 50% lighter than metals, and have excellent heat resistance and wear resistance. However, when CFRP composites suffer impact damage, destruction of fiber and interface delamination occur. This causes an unexpected deterioration of strength, and for this reason it is very difficult to ensure the reliability of the excellent mechanical properties. Therefore, for the destruction mechanism in bending with impact damage, this study investigated the reinforcement data regarding various external loads by identifying the consequential strength deterioration. Specimens were damaged by impact with a steel ball propelled by air pressure. Decrease in bending strength caused by the tension and compression of the impact side, and depending on the lamination direction of fiber and interface inside the specimen. From the bending test it was found that the bending strength reduced when the impact energy increased. Especially in the case of compression on the impact side, as tensile stress occurred at the damage starting point, causing rapid failure and a substantially reduced failure strength.

• 한국표면공학회지
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• 제50권4호
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• pp.259-265
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• 2017

5000 series aluminium alloys and austenitic stainless steels have excellent corrosion resistance and sufficient strength, which are widely used as materials for marine equipment and their parts in the marine environment. The corrosion characteristics of materials are important factors for selecting the appropriate material due to fluid component changes in the estuarine and coastal areas where seawater and fresh water are mixed. Therefore, for 5083 Al alloy, STS304 and STS316L widely used in the marine environment, anodic polarization experiments were performed to compare the corrosion damage characteristics of each material by three kinds of solutions of 100 % tap water, 50 % tap water+50 % natural seawater and 100 % natural seawater. As a result of the anodic polarization experiments, aluminum alloy (5083) caused locally corrosion on the surface in the tap water, and corrosion damage occurred all over the surface when the seawater was included. Stainless steels (STS304 and STS316L) presented almost no corrosion damage in tap water, but they grew pitting corrosion damage with increasing seawater concentration. STS316L showed better corrosion resistance than STS304.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.167-170
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• 2002

The influence of Si surface damage on Ni-silicide with TiN Capping layer and the effect of $H_2$ anneal are characterized. Si surface is intentionally damaged using Ar Sputtering. The sheet resistance of NiSi formed on damaged silicon increased rapidly as Ar sputtering time increased. However, the thermal stability of Ni-Si on the damage silicon was more stable than that on at undamaged Si, which means that damaged region retards the formation of NiSi. It was shown that $H_2$ anneal and TiN capping is highly effective in reducing NiSi sheet resistance.

• The Plant Pathology Journal
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• 제39권5호
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• pp.449-465
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• 2023

Plants are challenged by various pathogens throughout their lives, such as bacteria, viruses, fungi, and insects; consequently, they have evolved several defense mechanisms. In addition, plants have developed localized and systematic immune responses due to biotic and abiotic stress exposure. Animals are known to activate DNA damage responses (DDRs) and DNA damage sensor immune signals in response to stress, and the process is well studied in animal systems. However, the links between stress perception and immune response through DDRs remain largely unknown in plants. To determine whether DDRs induce plant resistance to pathogens, Arabidopsis plants were treated with bleomycin, a DNA damage-inducing agent, and the replication levels of viral pathogens and growth of bacterial pathogens were determined. We observed that DDR-mediated resistance was specifically activated against viral pathogens, including turnip crinkle virus (TCV). DDR increased the expression level of pathogenesis-related (PR) genes and the total salicylic acid (SA) content and promoted mitogen-activated protein kinase signaling cascades, including the WRKY signaling pathway in Arabidopsis. Transcriptome analysis further revealed that defense-and SA-related genes were upregulated by DDR. The atm-2atr-2 double mutants were susceptible to TCV, indicating that the main DDR signaling pathway sensors play an important role in plant immune responses. In conclusion, DDRs activated basal immune responses to viral pathogens.

• Corrosion Science and Technology
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• 제18권6호
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• pp.292-299
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• 2019

The hull material of a high-speed ship may cause erosion damage from fluid impact. When physical erosion and electrochemical corrosion combine, erosion corrosion damage occurs. The aluminum ship is vulnerable to erosion corrosion because it can be operated at high speed. Thus, in this study, Al5052-O and Al6061-T6 aluminum alloys for the marine environment were selected as experimental materials. The erosion corrosion resistance of Al5052-O and Al6061-T6 aluminum alloys in seawater was investigated by an erosion test and potentiodynamic polarization test at the various flow rate (0 m/s, 5 m/s, 10 m/s, 15 m/s, 20 m/s). Erosion corrosion characteristics were evaluated by surface analysis, 3D analysis, SEM analysis, and the Tafel extrapolation method. The results of surface damage analysis after the erosion test showed that Al6061-T6 presented better erosion resistance than Al5052-O. The results of the potentiodynamic polarization test at the various flow rate, corrosion current density by Tafel extrapolation presented lower values of Al6061-T6 than Al5052-O. Al5052-O showed more surface damage than Al6061-T6 at all flow rates. Consequently, Al6061-T6 presented better erosion corrosion resistance than Al5052-O. The results of this study are valuable data for selecting hull material for an aluminum alloy vessel.

• Corrosion Science and Technology
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• 제11권6호
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• pp.263-269
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• 2012

Copper alloys are commonly applied to ship's propellers, pumps and valves which are serviced in seawater due to their good castability and corrosion resistance. In the environment of high flow velocity, however, erosion damage predominates over corrosion damage. In particular, the cavitation in seawater environment accelerates surface damage to copper alloys, resulting in degradation of products and economic losses and also threatening safety. The surface was coated with WC-27NiCr by high velocity oxygen fuel(HVOF) spraying technique to attain durability and cavitation resistance of copper alloys under high velocity/pressure flow. The cavitation test was performed for the WC-27NiCr coating deposited by HVOF in seawater at the amplitude of $30{\mu}m$ with seawater temperature. The cavitation at $15^{\circ}C$ caused exfoliation of the coating layer in 17.5 hours while that of $25^{\circ}C$ caused the exfoliation in 12.5 hours. When the temperature of seawater was elevated to $25^{\circ}C$ from $15^{\circ}C$, more damage was induced by over 160%. Although WC-27NiCr has good durability, corrosion resistance and eletrochemical stability, the cavitation damage rate of the coating layer could remarkably increase at the elevated temperatures under cavitation environments.

• 한국결정성장학회지
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• 제5권1호
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• pp.1-10
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• 1995

CZ법을 이용하여 합치용융조성(congruent) $LiNbO_3$ 및 광손상에 큰 저항성을 보이는 $LiNbO_3$ : Mg 단결정에 MgO 첨가량을 2, 5 및 7 mol%로 변화시키면서 육성하여, 보상 방법으로 광손상을 측정하였다. 5 mol% 이상의 MgO 첨가시 광흡수단 및 $OH^-$ 흡수밴드의 특성이 크게 변화함을 관찰함으로써 MgO 첨가량에 일정한 역치(threshold)가 존재함을 확인하였다. $LiNbO_3$ : Mg 단결정에서는 5 mol% 이상의 MgO 첨가시 Mg가 Nb 자리를 차지하여$Mg_{Nb}^{2+}$를 형성함에 따라 광손상에 대한 저항이 크게 향상될 수 있다. 실제로 융액에 5 mol% 이상의 MgO 첨가시)$LiNbO_3$ : Mg 단결정의 광손상 저항이 3배 이상 향상되었다.