• Journal of Electrical Engineering and information Science
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• v.3 no.1
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• pp.51-57
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• 1998

As DAS becomes a common practice, various operational tools are needed. This paper proposes the new restoration strategy considering the coordination of the protective devices and the generalized method for determining the switching sequence. The effectiveness of the proposed method has been tested on the various real systems.

• Particle and aerosol research
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• v.18 no.4
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• pp.87-95
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• 2022

Currently, droplet protective screens (DPSs) are used to prevent the spread of respiratory diseases. As virus particles can maintain their infective in indoor environments, recent studies have investigated the risk of airborne transmission. However, the ability of DPSs to block airborne transmission has not been verified yet. In this study, the preventive ability of DPSs against droplet and airborne transmission was evaluated. Moreover, the effectiveness of a Portable air purifier (PAP) was investigated. According to results, in a simulated room where an infectious person spoke, the DPS blocked more than 90% of the micron-sized droplets (with a diameter larger than 1 ㎛) transmitted to the front of the infectious person. However, sub-micron droplets (with a diameter smaller than 1 ㎛) passed through the DPS and spread in a room. However, the PAP reduced the amount of both micron and sub-micron droplets transmitted to the front of the infectious person. When the PAP airflow direction was set from the DPS surface to the free space near the infectious person, improved prevention against droplet and airborne transmission was recorded. However, airborne transmission was accelerated when the PAP airflow direction was set from the free space to the DPS surface.

• Korean Security Journal
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• no.49
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• pp.133-154
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• 2016

The Seoul subway system has one of the highest transport shares in the city of Seoul. A high number of passengers means that a high level of crimes of all kinds occur on the city's subway system. As such, Seoul Metro, created the Subway Protective Guards System in 2009, in an effort to enhance safety on the subway. But this innovative new system did not resolve problems. In fact, many citizens came to question the effectiveness of the new system, as it did not yield tangible results. This study seeks to deduce the problems and activation strategy of the Subway Protective Guards System. An in-depth study was conducted by interviewing subway protective guards who were squad leaders with five or more years of relevant work experience. Semi-structured interview analysis was utilized to evaluate their responses. Specifically, their responses were deduced to identify the strengths and weaknesses internal to the system and the opportunities and threats posed by the environment external to the system. This study presents measures to improve the system based on the aforementioned analysis. Measures for improvement focused on the following areas: the adoption of an education system in response to terror; recruitment and the possibility of becoming a permanent employee; obtaining partial judicial powers; improvement of work environment; and intensifying the promotion of the system.

• Nutritional Sciences
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• v.6 no.3
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• pp.160-166
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• 2003

To examine the evidence that wheat bran is protective against breast cancer development and that its main mechanism of action is by modulating estrogen metabolism. This review explores the role of different experimental factors on the anticancer effects of wheat bran and the relationship of changes to estrogen metabolism by wheat bran on breast cancer risk The timing of the experimental diets in relation to carcinogen administration, the length of feeding of the experimental diets, and the level of dietary fat had an impact on the effectiveness of different doses of wheat bran in reducing breast carcinogenesis. Wheat bran supplementation resulted in significant reductions in human plasma estrogen levels but not in that of animals tested. The change in excretory metabolism of estrogen by wheat bran feeding in animals was not related to any of the tumor indices measured. The protective effect of wheat bran in breast carcinogenesis is greatest at the promotional phase and when supplemented in a high fat diet. Doses of wheat bran in the 9-12% range in diet have been consistently protective. The inconsistency observed with higher doses of wheat bran may be dependent on the animal model used. Although wheat bran's inhibitory effects on tumor growth may involve changes to estrogen metabolism, the fiber and phytochemical components of wheat bran may also act through estrogen-independent mechanisms. For a better understanding of the effect of wheat bran on breast carcinogenesis, studies comparing the effects of different wheat bran components both alone and in combination need to be performed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.66-71
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• 2003

Electronic equipments made from integrated circuits and small-sized semiconductors is protected by surge protective devices(SPDs) such as ZnO varistors, Zener diode and gas discharge tube from lightning overvoltages. However the clamping voltage of SPDs is greatly influenced by the method of installing the SPDs. In this paper, the protective effects of SPDs according to types of system groundings were experimentally investigated. The separate grounding is a particularly undesirable way to install SPDs. The effectiveness of the common grounding point for ZnO varistors is more pronounced than that for gas discharge tubes. The common grounding at the terminal of SPDs is recommended as a best method of installing SPDs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.426-433
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• 2014

The high-altitude electromagnetic pulse(HEMP) generated by a high-altitude nuclear explosion. This paper presents the comparison of electric field penetration in Bell laboratories and IEC 61000-2-9 standard when HEMP source penetrates through Naval Warship conducted coupling path and radiated coupling path. Also we analyze the effects of two kinds of coupling and propose Protective measures. Simulation results confirm IEC 61000-2-9 standard is more strict than the Bell Laboratories standard except for a lower frequency band, so we proposed IEC 61000-2-9 standard as a Naval HEMP standard. Finally, we offer the protective measures such as the shielding coating, Honeycomb ventilation, TVS in order to meet the military criteria.

• Corrosion Science and Technology
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• v.6 no.2
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• pp.62-67
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• 2007

Several heavy duty coatings at an every kind industry facilities to various systems currently have been applied review to the many industry fields. Corrosion-protective characteristics in the case of novolac epoxy among them and unsaturated polyester have been applied most widely. epoxy and flake heavy duty coatings are applied for such reason in an every kind facilities(stack, FGD, cooler, chemical tank etc) of a fossil-fuel power plants Cases of the fossil-fuel power plants are exposed to more severe corrosion environment compared with other facilities and It is difficult to display the performance of long-term method at apply to be the partial. Our study shows fluoro-polymer composite coating method to overcome of the limit. The comparison did previous method and heavy duty coating about FGD plants most at a corrosion environment among fossil-fuel power plants. Additionally, other facilities examined different heavy duty method. The design mode of fluoro-polymer composite coating according to an every kind facilities show extensive methods that are characteristic revelation of film(top, middle and primer layer) composition of the paint, film thickness in accordance with a facilities corrosion and the corrosion protective effectiveness to come into being use fluoro-polymer composite with heavy duty paint(epoxy).

• Korean Journal of Pharmacognosy
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• v.15 no.2
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• pp.98-103
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• 1984

A ginseng preparation consisting of ginseng ext., lycii fructus ext., four vitamins and caffeine was chosen and its efficacy was evaluated with respect to nutritional supplement, antifatigue activity and liver protective action. Animals administered orally in both one-third and three fold doses of the preparation showed no significant increments of their body weights when compared with those of the normal animals, suggesting no supplemental activity. However, the preparation in the above two doses significantly prolonged swimming time to 53 and 63%, respectively. Ginseng and lycii fructus ext. were found to be responsible for the antifatigue activity. And also the preparation significantly inhibited lipid peroxidation of mouse liver after ethanol-induced acute intoxication.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.15-18
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• 2009

In recent years electric devices and telecommunication facilities were often damaged by surge generated lightning discharge. When the service was interrupted by failure of electrical devices due to surge the social loss is very enormous. Therefore in order to protect electrical systems against lightning, SPDs(Surge protective device) have been used But damaged SPDs often make some troubles like fire and interrupt of service. In this work, 3rd harmonic leakage current defection method was applied as the diagnosis of SPD degradation and the effectiveness of this method was verified by field survey.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2089-2092
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• 2010

There are many cases that interrupt the production process because of malfunctions caused by electronic circuit boards which control equipment, but it is difficult to distinctly identify the causes in many cases. Especially, CMOS devices with the control logic circuit return automatically to normal state after their own faults. Therefore it is not easy to analyze the problems with electronic circuit boards. Recently, nuclear power plant experienced a failure due to the malfunction of electronic circuit boards and it was identified that the reason of the malfunction was because of latch-up phenomenon caused by external surge in electronic devices. This paper presents the causes and the phenomenon of latch-up by experiment and also a way using counter EMF diodes, noise filters and surge protective devices to prevent latch-up phenomenon from electronic circuit boards, finally confirms the effectiveness of the result by experiment.