• 한국컴퓨터정보학회논문지
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• 제8권3호
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• pp.124-129
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• 2003

최근들어 인터넷상에서 디지털 컨텐츠의 보안 방법은 절실해 지고 있는 상황이다. 그 방법으로 가시적인 워터마크를 컨텐츠에 삽입한 경우가 많은데, 이는 원래의 컨텐츠를 훼손시킬 뿐만 아니라 워터마크를 손쉽게 제거가 가능하다. 본 논문에서는 로고 영상을 비가시적인 워터마크로 삽입하고, 이를 검출하는 알고리즘을 제안한다. 기존의 연구들은 이에 대해 뚜렷이 제시한 논문이 없고 이의 필요성이 절실한 상황이다. 실험 결과 제안한 알고리즘이 타당함을 증명하였으며, 향후 이용 가치가 충분히 있는 것으로 판명되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.217-219
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• 2003

This paper presents a distance relaying algorithm for a transmission line protection with MAS. First, the voltage and fault current of the opposite side are represented as a function of those of the measuring end using source voltages of both ends. These voltages are assumed to be obtained from the transformers protecting agents, periodically in normal state. Then, the fault location expression, independent of fault resistance, is derived with voltage and current in only one end of faulted line used. The suggested algorithm is applied to a simple system with two power sources to show its effectiveness.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.23-24
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• 2007

Most of modern wind turbines employs a doubly-fed induction generator (DFIG) system because it has many advantages due to variable-speed operation, relatively high efficiency and it small converter size. The DFIG system uses a wound rotor induction machine so that the magnetizing current of the generator can be fed from both the stator and the rotor. This paper presents a protection relaying algorism for DFIG using the DQ equivalent circuits. The induced voltages calculated from the stator and rotor sides are nearly the same in the steady state. They become different in the DQ equivalent circuits during an internal fault. The proposed algorithm compares the inducted voltages estimated from the stator and the rotor circuit converted into the stationary reference frame. If the difference between the induced voltages exceeds the threshold, the proposed algorithm detects an turn-to-turn fault.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.14-16
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• 2004

A DC railway system has low feeder voltage, The remote fault current can be smaller than the current of load starting. So it is important to discriminate between the small fault current and the load starting current. The load starting current increases step by step but the fault current increases all at once. As for the load starting current, the time constant of load current at each step is much smaller than that of the fault current. To detect faults in DC railway systems, an algorithm using the time constant calculated by the method of least squares was presented. But, It have a weakness about harmonic to calculate time constant. So in this paper, new protection algorithm for DC railway systems using estimation of time constant based on fourier transform was presented.

• 한국정보통신학회논문지
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• 제12권1호
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• pp.215-222
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• 2008

본 논문에서는 기존 RFID 보안 기법에서 나타나는 도청으로 인한 정보 유출 문제를 분석하고 이를 해결하기 위하여 RFID에 SEED 보안 알고리즘을 응용한 부분 라운드 및 부분 암호화 기법을 적용하고자 한다. 기존에 제시된 많은 태그보안 기법들이 있으나, 보안과 구현의 문제에서 아직 현실적인 접근이 미비한 실정이다. 따라서, 본 논문을 통해 보다 현실적인 구현의 관점에서 하나의 아이디어를 제공하고, SEED기반의 비밀키 기반 암호화 알고리즘 기법을 적용하여 태그에서 리드간의 전송 취약구간인 백워드 채널상의 정보보안을 해결책을 제시하였다.

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.58-63
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• 2019

Lithium-ion batteries used for IT, automobiles, and industrial energy-storage devices have battery management systems (BMS) to protect the battery from abnormal voltage, current, and temperature environments, as well as safety devices like, current interruption device (CID), fuse, and vent to obtain positive temperature coefficient (PTC). Nonetheless, there are harmful to human health and property and damage the brand image of the manufacturer because of smoke, fire, and explosion of lithium battery packs. In this paper, we propose a systematic protection algorithm combining battery temperature, over-current, and interconnection between protection elements to prevent copper deposition, internal short circuit, and separator shrinkage due to frequent and instantaneous over-current discharges. The parameters of the proposed algorithm are suggested to utilize the experimental data in consideration of battery pack operating conditions and malicious conditions.

• 전기학회논문지P
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• 제63권3호
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• pp.149-156
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• 2014

Generator of hydroelectric generating unit is to be protected by the digital protection IED. Now, any IED of large capacity for hydro power plant was not developed by domestic technology. This is because it is required for the generator of the high reliability technology and considered as due to the sale of the market of IED device is small. However, the protection IED must be develop by domestic technology to meet the advanced needs of the construction and replacement of electrical equipment in accordance with the new power plant development. In this paper, a digital algorithms for protection IED of large size of hydroelectric generating unit were designed. The algorithms consist of the stator protection, anti-motoring, overexcitation and loss of excitation. The performance of the algorithms were evaluated by using the simulation data collected from the PSCAD/EMTDC software. From test results, it can be seen that the developed algorithms were not maloperation.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.612-620
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• 2017

Relay coordination in power system is a complex problem and so far, meta-heuristic algorithms and other methods as an alternative approach may not properly deal with large scale relay coordination due to their huge time consuming computation. In some cases the relay coordination could be unachievable. As the urgency for a proper approach is essential, in this paper an innovative and simple relay coordination method is introduced that is able to be applied on optimization algorithms for relay protection coordination. The objective function equation of operating time of relays are divided into two separate functions with less constraints. As the analytical results show here, this equivalent method has a remarkable speed with high accuracy to coordinate directional relays. Two distribution systems including directional overcurrent relays are studied in DigSILENT software and the collected data are examined in MATLAB. The relay settings of this method are compared with particle swarm optimization and genetic algorithm. The analytical results show the correctness of this mathematical and practical approach. This fast coordination method has a proper velocity of convergence with low iteration that can be used in large scale systems in practice and also to provide a feasible solution for protection coordination in smart grids as online or offline protection coordination.

• 전기학회논문지
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• 제57권4호
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• pp.706-714
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• 2008

In this paper, we suggest a practical and flexible system architecture for JTAG(Joint Test Action Group) protection of application processors. From the view point of security, the debugging function through JTAG port can be abused by malicious users, so the internal structures and important information of application processors, and the sensitive information of devices connected to an application processor can be leak. This paper suggests a system architecture that disables computing power of computers used to attack processors to reveal important information. For this, a user authentication method is used to improve security strength by checking the integrity of boot code that is stored at boot memory, on booting time. Moreover for user authorization, we share hard wired secret key cryptography modules designed for functional operation instead of hardwired public key cryptography modules designed for only JTAG protection; this methodology allows developers to design application processors in a cost and power effective way. Our experiment shows that the security strength can be improved up to $2^{160}{\times}0.6$second when using 160-bit secure hash algorithm.

• 한국멀티미디어학회논문지
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• 제17권7호
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• pp.769-777
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• 2014

With the rapid interest in Geographic Information System (GIS) contents, a large volume of valuable GIS dataset has been distributed illegally by pirates, hackers, or unauthorized users. Therefore the problem focus on how to protect the copyright of GIS vector map data for storage and transmission. At this point, GIS security techniques focusing on secure network and data encryption have been studied and developed to solve the copyright protection and illegal copy prevention for GIS digital map. But GIS vector map data is very large and current data encryption techniques often encrypt all components of data. That means we have encrypted large amount of data lead to the long encrypting time and high complexity computation. This paper presents a novel selective encryption scheme for GIS vector map data protection to store, transmit or distribute to authorized users using K-means algorithm. The proposed algorithm only encrypts a small part of data based on properties of polylines and polygons in GIS vector map but it can change whole data of GIS vector map. Experimental results verified the proposed algorithm effectively and error in decryption is approximately zero.