• Korean Journal of Plant Resources
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• v.31 no.3
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• pp.228-236
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• 2018

In this study, we evaluated the antioxidant activity and protective effects against oxidative DNA damage of the ethyl acetate fraction from the callus of Abeliophyllum distichum Nakai (ECA). Callus of A. distichum was induced on MS medium containing NAA (1 mg/L) and 2,4-D (1 mg/L), and a sufficient amount was obtained for the extraction by subculture. Acteoside was analyzed and quantified (0.39 mg/g callus) from ECA using the high-performance liquid chromatography-photodiode array detector method. ECA showed very high antioxidative activity as revealed by DPPH and ABTS scavenging assays. The $IC_{50}$ values were 12.4 and $6.8{\mu}g/ml$, respectively. ECA showed protective effects against oxidative DNA damage evaluated by using ${\Psi}X-174$ RF I plasmid DNA. It also inhibited DNA damage by suppressing the oxidative stress-induced protein and mRNA levels of ${\gamma}$-H2AX and p53 in NIH/3T3 cells. In conclusion, ECA protects against oxidative DNA damage through its powerful antioxidant activity.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1789-1794
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• 2014

This paper suggests an application method for a superconducting fault current limiter (SFCL) using an evaluation index to estimate the risk regarding the short-circuit capacity of the circuit breaker (CB). Recently, power distribution systems have become more complex to ensure that supply continuously keeps pace with the growth of demand. However, the mesh or loop network power systems suffer from a problem in which the fault current exceeds the short-circuit capacity of the CBs when a fault occurs. Most case studies on the application of the SFCL have focused on its development and performance in limiting fault current. In this study, an analysis of the application method of an SFCL considering the risk of the CB's short-circuit capacitor was carried out in situations when a fault occurs in a loop network power system, where each line connected with the fault point carries a different current that is above or below the short-circuit capacitor of the CB. A loop network power system using PSCAD/EMTDC was modeled to investigate the risk ratio of the CB and the effect of the SFCL on the reduction of fault current through various case studies. Through the risk evaluations of the simulation results, the estimation of the risk ratio is adequate to apply the SFCL and demonstrate the fault current limiting effect.

• Journal of Yeungnam Medical Science
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• v.4 no.1
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• pp.17-23
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• 1987

New born rat heart cells were dissociated using trypsin and/or collegenase to elucidate the dissociation efficiency of these two enzymes. And the effect of dimethyl sulfoxide during and immediately after cell dissociation was also investigated to clarify the so-called protective activity of dimethyl sulfoxide on cell performance. The results can be summarized as follows. 1. Cold trypsin 18 hours pretreatment followed by warm collagenase treatment resulted best cell viability and cell yield. 2. Single, warm trypsin treatment gave the poorest result. 3. Dimethyl sulfoxide did not seem to play any protective role during or immediately after rat heart cell dissociation. It had very damaging effect on rat heart cells.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.76-82
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• 1998

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. Current work is emphasized on the investigation of the air jet effect on the protective collar type labyrinth seal. To improve the sealing capability of conventional labyrinth seal, air jet is injected against through the leakage flow. It has a combined geometry of a protective collar type and an air jet type. In this study, both of a numerical analysis by CFD(Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. Both of the turbulence and the compressible flow model are introduced in CFD analysis. The sealing effect of the leakage clearance and the air jet magnitude are studied for various parameter in the experiment. The results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effects of sealing improvement are explained as decreasing of effective leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger.

• Journal of the Society of Disaster Information
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• v.12 no.4
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• pp.381-388
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• 2016

In this study, we surveyed the supply and perception of Personal Protective Equipments for firefighters. As a result, most of the respondents answered that they were paid in accordance with the supply standard, but 12% of the respondents said that there were insufficient equipment. Also, satisfaction with the performance of the equipment is mostly satisfied, but the safety gloves are more than 50% dissatisfied. In summing up the results of the survey, it is urgently necessary to improve the current supply standard, which is determined by the life of PPE, to the replacement period according to the using time or frequency. Also, a new standard should be prepared through the follow - up study.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.73-73
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• 1999

A large area negative metal ion beam source is developed. Kinetic ion beam of the incident metal ions yields a whole nucleation and growth phenomena compared to the conventional thin film deposition processes. At the initial deposition step one can engineer the surface and interface by tuning the energy of the incident metal ion beams. Smoothness and shallow implantation can be tailored according to the desired application process. Surface chemistry and nucleation process is also controlled by the energy of the direct metal ion beams. Each individual metal ion beams with specific energy undergoes super-thermodynamic reactions and nucleation. degree of formation of tetrahedral Sp3 carbon films and beta-carbon nitride directly depends on the energy of the ion beams. Grain size and formation of polycrystalline Si, at temperatures lower than 500deg. C is obtained and controlled by the energy of the incident Si-ion beams. The large area metal ion source combines the advantages of those magnetron sputter and SKIONs prior cesium activated metal ion source. The ion beam source produces uniform amorphous diamond films over 6 diameter. The films are now investigated for applications such as field emission display emitter materials, protective coatings for computer hard disk and head, and other protective optical coatings. The performance of the ion beam source and recent applications will be presented.

• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.276-282
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• 2010

There are the impregnating layer formation by surface protective materials or impregnants and the adhesion method by polymer, FRP sheet or steel plate in the surface protective method of concrete structure. The surface impregnation method by impregnants improves the durability of concrete structure by modifying the structure of the concrete surface and also have a merit that can be shortly applied in place without the decrease of concrete surface appearance and is easily applied again. This study is interested in manufacturing the concrete surface impregnants including lithium and potassium silicate for the repair of the exposed concrete and the color concrete requiring the advanced function in view of the concrete appearance. The durability and porosity properties was tested for the review of application. The result of this study show that the effective content of silicate ranges 5 to 20% and the separate application of the first impregnant and the second impregnant is effective for the optimum performance. The adhesion in tension is slightly increased but the reinforcement of concrete substrate is slight. So, the concrete impregnant of this study is more desirable for the improvement of durability rather than the reinforcement.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.340-343
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• 2001

In an electrical network, electrical power are transmitted by a various of protection, isolation and control electric circuit devices. This thesis deals with the protection function between circuit-breakers. The protective coordination concerns the behaviour of two devices placed in series in an electrical network, with a short-circuit downstream circuit-breaker. It has two basic principles: First, discrimination which is an increasing requirement of low voltage electrical distribution systems. Second, which is less well known: cascading, which consists of installing a device, whose breaking capacity is less than the three-phase short-circuit current at its terminals and helped by main circuit-breaker. The important advantage of cascading is to be able to install at a branch circuit-breaker of a lesser performance without endangering the safety of the installation for more economical usage. To determine and guarantee co-ordination between two circuit breakers, it is necessary to carry out a theoretical approach, first, and then confirm the results by means of standard tests. This is illustrated in appendix A of IEC 947-2.

• Carbon letters
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• v.6 no.2
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• pp.71-78
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• 2005

Anti-oxidation coatings are the key technique for carbon/carbon (C/C) composites used as the thermal structural materials. The microstructure and oxidation behavior of several kinds of high-performance ceramic coatings for C/C composites prepared in Northwestern Polytechnical University were introduced in this paper. It showed that the ceramic coatings such as SiC, Si-$MoSi_2$, SiC-$MoSi_2$, $Al_2O_3$-mullite-SiC and SiC/yttrium silicate/glass coatings possessed excellent oxidation resistance at high temperatures, and some of these coatings were characterized with excellent thermal shock resistance. The SiC-$MoSi_2$ coating system has the best oxidation protective property, which can effectively protect C/C composites from oxidation up to 1973 K. In addition, the protection and failure reasons of some coatings at high temperature were also provided.

• Journal of the Korean Ceramic Society
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• v.37 no.8
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• pp.760-767
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• 2000

Recently, the protection of construction is demanded with environmental pollution. These protect modes are use of concrete admixture, coat of protective polymer and impregnate of surface with chemicals etc. The most widely used impregnation is economical and effective. The define of Impregnation for construction protect is reacted in and consolidated substrate after absorbed. The impregnation agents are Polyesters, Acrylic monomers, Epoxy and Silicone derivatives. Commonly, because the Silane has good water repellency and environmental advantages that it widely used to water proofing agents, dampproofing agents and absorption reducer for concrete of bridges. When application of Silane, it occurs pollution and harmfulness as included organic solvent. The manufactures have tired to emulsification of Silane for the reducing of the defects. The Silane emulsion is vary unstable and does not stored long periods, and it is diminished in good properties with internal reaction. In this study we tried to emulsification of Silane for effectiveness improvement and reduce pollution and hazard and discussed properties variation of emulsion. The Silane emulsions are achieved emulsifying with W/O and O/W type surfactants. It used 0.24% PVA as protective colloid and stable phase is creamy. The creamy Silane emulsion performance as the penetration depth and water absorption rate are above 4 mm and below 0.1. It stable about 6 month at room temperature.