• Nuclear Engineering and Technology
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• v.31 no.2
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• pp.192-201
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• 1999

This paper proposes an improved signal processing strategy for accurate feedwater flowrate estimation in nuclear power plants. It is generally known that ∼2% thermal power errors occur due to fouling Phenomena in feedwater flowmeters. In the strategy Proposed, the noises included in feedwater flowrate signal are classified into rapidly varying noises and gradually varying noises according to the characteristics in a frequency domain. The estimation precision is enhanced by introducing a low pass filter with the wavelet analysis against rapidly varying noises, and an autoassociative neural network which takes charge of the correction of only gradually varying noises. The modified multivariate stratification sampling using the concept of time stratification and MAXIMIN criteria is developed to overcome the shortcoming of a general random sampling. In addition the multi-stage robust training method is developed to increase the quality and reliability of training signals. Some validations using the simulated data from a micro-simulator were carried out. In the validation tests, the proposed methodology removed both rapidly varying noises and gradually varying noises respectively in each de-noising step, and 5.54% root mean square errors of initial noisy signals were decreased to 0.674% after de-noising. These results indicate that it is possible to estimate the reactor thermal power more elaborately by adopting this strategy.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1521-1529
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• 2009

There is a serious unfairness problem between upstream and downstream flows of AP in IEEE 802.11 Wireless LAN. This problem is because Wireless LAN's DCF MAC protocol provides AP with equal channel access priority to mobile noded. Also, it makes this problem worse that the TCP's Data segment loss is more effective on throughput than the TCP's ACK segment. In this paper, we first make several simulations to analysis the unfairness in the various point of view and to find reasons of the unfairness. Also, this paper presents AP's scheduling scheme to alleviate the unfairness problem and evaluate the scheme through ns2 simulator.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.41-48
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• 2010

Intrusion detection forms a vital component of internet security. To keep pace with the growing trends, there is a critical need to replace single layer detection technology with multi layer detection. Different types of Denial of Service (DoS) attacks thwart authorized users from gaining access to the networks and we tried to detect as well as alleviate some of those attacks. We have proposed a novel cross layer intrusion detection architecture to discover the malicious nodes. The information available across different layers of protocol stack are exploited in order to improve the accuracy of detection. We have used cooperative and distributive anomaly intrusion detection with data mining technique to enhance the proposed architecture. The simulation of the proposed architecture is done in OPNET simulator and the results are analyzed.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.172-178
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• 2014

In terms of an accident management, the cases causing severe core damage need to be analyzed and arranged systematically for an easy access to the results since the Three Mile Island (TMI) accident. The objectives of this paper are to explain how to identify the plant response and cope with its vulnerabilities using the probabilistic safety assessment (PSA) quantified results and severe accident database SARDB(Severe Accident Risk Data Bank) based on sequences analysis results. Although PSA has been performed for the Korean Standard Power Plants (KSNPs), and that it considered the necessary sequences for an assessment of the containment integrity. The developed Database (DB) system includes a graphical display for a plant and equipment status, previous research results by a knowledge-based technique, and the expected plant behaviour. The plant model used in this paper is oriented to the cases of loss of coolant accident (LOCA) is be used as a training simulator for a severe accident management.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.199-201
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• 2016

The performance of navigational equipments is advanced, but the importance of the practical capability of bridge device by ship's officer, ie the ability of risk prediction and the obligation of avoidance for reducing sea accident, has been constantly augmenting. This abilities and obligation may be represented in the cognitive competence of navigational officer. Different levels of ship's bridge team was carried out rescue maneuvering by ship handling simulator and then it analyzed the resulting of initial response in cognitive progress by case based on trajectory. Further, the data will be used as training and evaluation model of cognitive situation.

• Journal of Navigation and Port Research
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• v.44 no.5
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• pp.375-381
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• 2020

The IMO has established a regulation for the ECDIS installation on ships based on the IHO S-57 standards. The ECDIS supports sailors in achieving a safe voyage by using ENCs and monitoring the information of their ship. However, the S-57 standards were developed as edition 3.1 and prohibited revision for more than 20 years. So, the IHO developed a new standard as S-100 into the hydrography and maritime field instead of updating the S-57 to edition 4.0. In this study, the new S-100 ECDIS was developed and verified with ENCs and the digital maritime safety information by using a ship steering simulator and by conducting an on-board sea-trial test. It evaluated the impact on ship operations if the next-generation navigation support system is introduced. Based on this research, the S-100 ECDIS will generate improvements such as safe voyages by providing various of real-time safety information and up-to-date data to ship and sailors.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.9
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• pp.747-754
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• 2013

This paper describes SCTE(System and Control unit Test Equipment) as an integrated test equipment for airborne SAR system and control unit. SCTE enhances reusability of test equipment by modular design for required functions and strengthens automatic testing and test convenience by providing functions such as script-based testing function and report generation function. Also, it includes a navigation data simulator which can simulate various flight conditions. In this paper, we details SCTE requirements, H/W and S/W design, implementation, and test results with control unit and SAR system.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.585-587
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• 1999

The rotorbody and rotor winding of generator are isolated by an insulator and the output characteristic of the generator is maintained in the best states. Only when an insulation resistance between them is over a certain extent. The aim of this research is to develop the simulator for rotor earth fault detection circuits. It is composed of the power resource which is to control the virtual field voltage, stepping motor which is to give virtual ground. It is possible to inspect with the device and program developed in this study in the same as real operating condition and evaluate the integrity of generator rotor through the function of data acquisition and graphic output. If these technologies will be applied to the inspection, prevent a damage of the generator and contribute to improve maintenance reliance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.912-921
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• 2015

In this paper, we introduce fuzzy inference-based real-time deterioration diagnosis system with the aid of infrared thermal imaging camera. In the proposed system, the infrared thermal imaging camera monitors diagnostic field in real time and then checks state of deterioration at the same time. Temperature and variation of temperature obtained from the infrared thermal imaging camera variation are used as input variables. In addition to perform more efficient diagnosis, fuzzy inference algorithm is applied to the proposed system, and fuzzy rule is defined by If-then form and is expressed as lookup-table. While triangular membership function is used to estimate fuzzy set of input variables, that of output variable has singleton membership function. At last, state of deterioration in the present is determined based on output obtained through defuzzification. Experimental data acquired from deterioration generator and electric machinery are used in order to evaluate performance of the proposed system. And simulator is realized in order to confirm real-time state of diagnostic field

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.189-194
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• 2017

An compressor that is combined with the rotor and pneumatic technology has been researching for the performance of pressure. However, the control of operations, an accurate diagnosis and the maintenance of compressor system are limited though the simple structure of compressor and compression are advantaged to reduce the energy. In this paper, the characteristic of the compressor operating under the normal or abnormal condition is realized. and the efficient diagnosis method is proposed through feature based analysis. Also, by using the GA (genetic algorithm) and SVM (support vector machine) of machine learning, the performance of feature analysis is conducted. Different misalignment mode of learning data for compressor is evaluated using the fault simulator. Therefore, feature based analysis is conducted considering misalignment mode of the compressor and the possibility of a diagnosis of misalignment is evaluated.