• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.5
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• pp.342-348
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• 2019

The emergency power supplies (EPSs) are required to increase battery sizing for protecting power source loss above designed criteria. This study proposes a sizing method for lithium-based batteries for EPSs in nuclear power plants on the basis of the calculation method for the required energy under variable conditions. The variable conditions are related with the characteristics of lithium-based batteries, such as the temperature of the location of EPS installation, aging, and design margin. The usage of lithium-based battery reduces the cost and installation space and enables the safe and long-term supply of power compared with the use of lead-acid battery.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.2
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• pp.207-213
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• 2009

Electrolytic capacitors have been widely used in power electronics system because of the features of large capacitance, small size, high-voltage, and low-cost. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. This paper proposed a novel fault diagnosis method of an electrolytic capacitor used for voltage smoothing in boost DC converter. The equivalent series resistance(ESR) of electrolytic capacitor estimated from FFT result of filtered waveform of capacitor voltage/current. Main advantage of the proposed method include circuit simplicity and easy implementation. Simulation and experimental results are shown to verify the performance of the proposed method.

• Smart Structures and Systems
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• v.5 no.4
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• pp.369-379
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• 2009

The sudden collapse of Interstate 35 Bridge in Minneapolis gave a wake-up call to US municipalities to re-evaluate aging bridges. In this situation, structural health monitoring (SHM) technology can provide the essential help needed for monitoring and maintaining the nation's infrastructure. Monitoring long span bridges such as cable-stayed bridges effectively requires the use of a large number of sensors. In this article, we introduce a probabilistic approach to identify optimal locations of sensors to enhance damage detection. Probability distribution functions are established using an artificial neural network trained using a priori knowledge of damage locations. The optimal number of sensors is identified using multi-objective optimization that simultaneously considers information entropy and sensor cost-objective functions. Luling Bridge, a cable-stayed bridge over the Mississippi River, is selected as a case study to demonstrate the efficiency of the proposed approach.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.372-376
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• 2010

Electrolytic capacitors have been widely used in power electronics system because of the features of large capacitance, small size, high-voltage, and low-cost. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. The estimation of the equivalent series resistance(ESR) is important parameter in life condition monitoring of electrolytic capacitor. This paper proposes a simple technique to measure the ESR of an electrolytic capacitor. This method uses a switching DC/DC boost converter to measure the DC Bus capacitor ESR of power converter. Main advantage of the proposed method is very simple in technique, consumes very little time and requires only simple instruments. Simulation results are shown to verify the performance of the proposed method.

• Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.10.1-10.14
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• 2019

Fish skin waste accounts for part of the solid waste generated from seafood processing. Utilization of fish skin by bioconversion into high-grade products would potentially reduce pollution and economic cost associated with treating fish processing waste. Fish skin is an abundant supply of gelatin and collagen which can be hydrolyzed to produce bioactive peptides of 2-20 amino acid sequences. Bioactivity of peptides purified from fish skin includes a range of activities such as antihypertensive, anti-oxidative, antimicrobial, neuroprotection, antihyperglycemic, and anti-aging. Fish skin acts as a physical barrier and chemical barrier through antimicrobial peptide innate immune action and other functional peptides. Small peptides have been demonstrated to possess biological activities which are based on their amino acid composition and sequence. Fish skin-derived peptides contain a high content of hydrophobic amino acids which contribute to the antioxidant and angiotensin-converting enzyme inhibitory activity. The peptide-specific composition and sequence discussed in this review can be potentially utilized in the development of pharmaceutical and nutraceutical products.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.209-213
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• 2005

To enhance the reliability of distribution transformers in service and to reduce the cost of maintaining and replaceing these, the condition and life of those insulating system should be evaluated accurately and the time to replace should be determined economically. Since the transformer failures related to insulation failure indicates that the primary cause is normally mechanical failure of integrity due to loss of mechanical strength as a result of degradation, the tensile strength characteristics of paper during ageing under accelerated conditions in insulating oil and research trends for assessing the life of insulating paper were investigated.

• Korean Journal of Organic Agriculture
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• v.21 no.3
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• pp.321-334
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• 2013

This case study surveyed management situations of environmentally friendly farming (EFF) and their awareness situations. Farmers are aging as an average age of 62-year old. The EFF did not increase farmer's income, however, farm income of EFF was more than that of conventional farming. Farm household liabilities showed large deviation among farmers. Livestock and greenhouse farm households have more liabilities because of facilities and feed cost. Farmers of EFF have been also cultivating conventional farming, but they don't plan much conversion intention of conventional farming into EFF owing to lack of differentiated and stable market for their environment-friendly agriculture products. And they are guessing that EFF income will usually not increase more. For increasing of EFF income, they think that it is necessary to enlarge production area, change to high-income crop, develop processing foods, change to organic farming and so on.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.199-204
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• 2010

The objective of this paper is to present new binder systems that can be applied in composite rocket propellants, to improve properties of these propellants not only for better performance, but also to reduce waste and pollution. These novel systems are based on the thermoplastic elastomer (TPE) binders, which consists of copolymers with the addition of a plasticizer, and additives. The effect of the novel TPE binder systems on the burning rate and mechanical properties of AP based propellants was studied. The results show that propellants based on the novel TPE binders have a better energy performance than today's workhorse hydroxyl terminated polybutadine/ammonium perchlorate propellant, exhibit a similar range of burning rate, possess appropriate mechanical properties, and exhibit good processing and aging characteristics at low cost.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.369-376
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• 2022

Accurately evaluating and predicting the performance of facilities is a key task in establishing a maintenance strategy for facilities. The importance of performance evaluation is becoming more pronounced, especially when the aging of facilities requires a huge budget. In this study, performance assessment models were developed for road and railway tunnels. Delphi analysis was performed to identify sub-elements necessary to evaluate the performance of a tunnel. The relative importance of the evaluation factors was derived from the AHP analysis. The correlation analysis was performed between each assessment factor and the final result to verify the significance of the model. For the correlation analysis, the survey data measured through precision safety diagnosis in tunnels in use was applied. The cost effectiveness analysis was also conducted according to the scenarios with different composition of performance factors in order to improve the practical applicability of the evaluation model developed in this study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.6-10
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• 2003

In our country, the housing materials of polymeric outdoor insulators have mainly been used EPDM or silicone rubber. EPDM housing materials had been widely used in the field for the first time. The reason why silicone has the high cost of production. But recently, most of the manufacturers that newly developed polymeric insulators make its choice of silicone housing. EPDM showed a good resistance to tracking. We compared the various characteristics for EPDM and silicone insulators that have similar type and design. Silicone insulators have more performance in flashover voltage test and leakage current measurement because of a good water repellent than EPDM ones. Also, the property of EPDM compared with silicone insulators greatly decreased after aging test in combined acceleration ageing facilities for 1000 hours.