• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.567-575
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• 2008

Transient security assessment(TSA) is becoming an essential requirement not only for security monitoring but also for stabilizing control of power systems under new electricity environments. It has already been pointed out that fast transient stability study is an important part for monitoring and controlling system security. In this paper, we discuss an energy function method for stabilizing control of transiently unstable systems by introducing generator tripping system to enhance the transient stability of power systems. The stabilization with less tripped power can be obtained by tripping the generators faster than out-of-synchronism relay. Fast transient stability assessment based on the state estimation and direct transient energy function method is an important part of the stabilizing scheme. It is possible to stabilize the transiently unstable system by tripping less generators before the action of out-of-synchronism relay, especially when a group of generator are going to be out-of-synchronism. Moreover, the amount of generator output needed for tripping can be decided by Transient Energy Function(TEF) method. The main contribution of this paper is on the stabilizing scheme which can be running in the Wide Area Control System.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.2
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• pp.32-40
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• 2018

Since 2000, the frequency of earthquakes beyond the 5.0 magnitude quake has been increasing in the Korean peninsula. For instance, the 5.0-magnitude earthquake in Baekryong-do in 2003 has occurred, and recent earthquake with Gyeongju(2016) and Pohang(2017) measured respectively magnitude of 5.2 and 5.8 on the Richter scale. As results, the public concern and anxiety about earthquakes are increasing, and therefore it is necessarily required for social infrastructure to reinforce seismic design and energy production facilities directly related to the national economy and security. This study represents the analysis of seismic performance evaluation methodology such as Seismic Margin Assessment (SMA), Seismic Probabilistic Risk Assessment (SPRA), High Confidence Low Probability Failure (HCLPF) in nuclear power plants in order to develop optimal seismic performance improvement. Current methodologies to evaluate nuclear power plants are also addressed. Through review of the nuclear structure evaluation past and current trend, it contributes to be the basis for the improvement of evaluation techniques on the next generation of nuclear power plants.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.9
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• pp.71-77
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• 2022

In times of war or emergencies, weapon systems, such as radars, must receive stable power. This can be achieved using improved onboard portable power systems made of steel containers. However, a breakdown can occur in the event of random vibration during transportation via a vehicle or train. Electrical-power shortages or restrictions pose a significant threat to security. In this study, Composite Wheeled Vehicle(CWV) data and rail cargo data with Acceleration Spectral Density(ASD), specified in MIL-STD-810H METHOD 514.8, were interpreted as input data of the three-axis random vibration method using ANSYS 19.2. Modal analysis was performed up to 500 Hz, and deformations in modes 1 to 117 were calculated to utilize all ASD data. The maximum equivalent stress in the three-axis direction was obtained using a random vibration analysis. Similarly, the margin of safety was calculated using the derived equivalent stress and material properties. Overall, the analysis verified that the portable container designed for the power supply system satisfied the required vibration demands.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.9-16
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• 2017

Recent advances in healthcare technologies along with improved medical care have led to a steady increase in life expectancy over the past few decades. As a result, the world population is aging rapidly. Various researches have been carried out to provide information and communication technologies based solutions that enhance the well-being of elderly people and provide them with a well margin of independency in their daily life. Ambient assisted living can be defined as the use of information and communication technologies in a person's daily living and working environment to enable them to stay active longer, remain socially connected and live independently into old age. Since the information transmitted in ambient assisted living systems is very sensitive, the security and privacy of such data are becoming important issues that must be dealt with. In this paper, we propose a novel lightweight authentication protocol for the ambient assisted living systems. The proposed authentication protocol not only supports several important security requirements needed by the ambient assisted living systems, but can also withstand various types of attacks. In addition, the security analysis results show that the proposed authentication protocol is more efficient and secure than the existing authentication protocols.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.183-186
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• 2006

It is studied the implementation possibility of some encryption algorithms which meet the performance requirements in the smart card used in the TETRA system End-to-End Encryption. It is measured the operation time of the algorithm in the smart card which has 32 bit smart card controller made by Samsung Electronics. The algorithms used in the performance comparison are AES, ARIA, 3DES, SEED, IDEA which are the domestic or international standards. The input and output time of the smart card are measured using the smart card protocol analyzer. The pure algorithm operation time is calculated by the repeated algorithm operations. This measurement results can be used as the criteria for the selection of algorithm which will be used in the TETRA End-to-End encryption system. The algorithm which has better performance can be used for the implementation of additional functions in the smart lard, because of the enough time margin.

• International Journal of Computer Science & Network Security
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• v.24 no.5
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• pp.217-223
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• 2024

The current study aimed to evaluate the effectiveness of using Support Vector Machine (SVM) for political affiliation classification. The system was designed to analyze the political tweets collected from Twitter and classify them as positive, negative, and neutral. The performance analysis of the SVM classifier was based on the calculation of metrics such as accuracy, precision, recall, and f1-score. The results showed that the classifier had high accuracy and f1-score, indicating its effectiveness in classifying the political tweets. The implementation of SVM in this study is based on the principle of Structural Risk Minimization (SRM), which endeavors to identify the maximum margin hyperplane between two classes of data. The results indicate that SVM can be a reliable classification approach for the analysis of political affiliations, possessing the capability to accurately categorize both linear and non-linear information using linear, polynomial or radial basis kernels. This paper provides a comprehensive overview of using SVM for political affiliation analysis and highlights the importance of using accurate classification methods in the field of political analysis.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.1
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• pp.33-43
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• 2023

The National Institute of Standards and Technology (NIST), which is working on the Post-Quantum Cryptography (PQC) standardization project, announced four algorithms that have been finalized for standardization. In this paper, we demonstrate through experiments that private keys can be exposed by Correlation Power Analysis (CPA) and Differential Deep Learning Analysis (DDLA) attacks on polynomial coefficient-wise multiplication algorithms that operate in the process of generating signatures using CRYSTALS-Dilithium algorithm. As a result of the experiment on ARM-Cortex-M4, we succeeded in recovering the private key coefficient using CPA or DDLA attacks. In particular, when StandardScaler preprocessing and continuous wavelet transform applied power traces were used in the DDLA attack, the minimum number of power traces required for attacks is reduced and the Normalized Maximum Margines (NMM) value increased by about 3 times. Conseqently, the proposed methods significantly improves the attack performance.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.129-130
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• 2006

This paper presents a optimal power flow calculation algorithm considering voltage and transient stability. In this method, voltage stability margin and transient stability constraints is incorporated into a optimal power flow calculation formulation to guarantee adequate voltage and transient security levels in power system. In addition, this paper provides the Effect of Nodal Price and decomposed Element in Power System Operation. This Effect can be applied in the Estimation of Electric rates because the Electric market will be Competitive Market. The proposed method is applied to IEEE-24 Reliability Test System and the results shows the effectiveness of the method.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.136-139
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• 2005

On-line dynamic security assessment is becoming more and more important for the stable operation of power systems as load level increases. The necessity is getting apparent under Electricity Market environments due to more various operating conditions. Fast transient stability analysis tool is required for contingency selection. The TEF(Transient Energy Function) method is a good candidate for this purpose. The clustering of critical generators is crucial for the precise and fast calculation of energy margin. In this paper, we propose a new method for fast decision of mode of instability by using stability indices. Case study shows very promising results.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.39-42
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• 2005

This paper presents a optimal power flow calculation algorithm considering voltage and transient stability In this method, voltage stability margin and transient stability constraints is incorporated into a optimal power flow calculation formulation to guarantee adequate voltage and transient security levels in power system. The proposed method is applied to IEEE-24 Reliability Test System and the results shows the effectiveness of the method.