• 정보보호학회논문지
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• 제19권2호
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• pp.11-21
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• 2009

NTRU는 1990년대 Hoffstein 등에 의해 제안된 격자(Lattice) 기반 공개키 암호체계로서 기존의 공개키 암호와 비교하여 동일한 안전성을 제공하면서 암호화 및 복호화 속도가 빠르며 양자 연산 알고리즘을 이용한 공격에도 강하다는 이점이 있어 많은 주목을 받고 있다. 본 논문에서는 단순 전력 분석 공격과 통계적 특성을 이용한 전력 분석 공격인 상관계수 전력 분석 공격에 대한 NTRU의 안전성을 분석하고, NesC로 구현한 NTRU의 연산을 Telos 모트(mote)에서 수행시켜 측정한 전력 소모 데이터에 상관계수 전력 분석 공격을 적용하여 개인키 정보를 복원하는 실험 결과를 보인다. 또한 이러한 전력 분석 공격을 방지하기 위한 대응 방법을 제시한다. 먼저, 단순 전력 분석 공격을 방지하기 위해 연산 결과를 저장할 배열을 0이 아닌 수로 초기화시키는 방법을 제안하고, 통계적 특성을 이용한 전력분석 공격을 방지하기 위해 연산 순서를 변경하거나 컨볼루션(convolution) 연산에 사용되는 피연산자들에게 무작위성(randomness)을 부여하여 같은 입력에 대해서 랜덤한 전력 소모를 보이도록 하는 방법을 제안한다.

• 제어로봇시스템학회논문지
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• 제19권11호
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• pp.1036-1042
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• 2013

In this paper, an elderly assistance system is developed based on Xenomai, a real-time development framework cooperating with the Linux kernel. A Kinect sensor is used to recognize the behavior of the elderly and A-star search algorithm is implemented to find the shortest path to the person. The mobile robot also generates a trajectory using a digital convolution operator which is based on a Bezier curve for smooth driving. In order to follow the generated trajectory within the control period, we developed real-time tasks and compared the performance of the tracking trajectory with that of non real-time tasks. The real-time task has a better result on following the trajectory within the physical constraints which means that it is more appropriate to apply to an elderly assistant system.

• KIEE International Transactions on Power Engineering
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• 제2A권3호
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• pp.95-101
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• 2002

This paper illustrates a new fuzzy effective load model for probabilistic and fuzzy production cost simulation of the load point of the composite power system. A model for reliability evaluation of a transmission system using the fuzzy set theory is proposed for considering the flexibility or ambiguity of capacity limitation and overload of transmission lines, which are subjective matter characteristics. A conventional probabilistic approach was also used to model the uncertainties related to the objective matters for forced outage rates of generators and transmission lines in the new model. The methodology is formulated in order to consider the flexibility or ambiguity of load forecasting as well as capacity limitation and overload of transmission lines. It is expected that the Fuzzy CMELDC (CoMposite power system Effective Load Duration Curve) proposed in this study will provide some solutions to many problems based on nodal and decentralized operation and control of an electric power systems in a competitive environment in the future. The characteristics of this new model are illustrated by some case studies of a very simple test system.

• 대한전기학회논문지:전력기술부문A
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• 제50권9호
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• pp.431-439
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• 2001

This Paper illustrates a new numerical analysis method using a nodal effective load model for nodal probabilistic production cost simulation of the load point in a composite power system. The new effective load model includes capacities and uncertainties of generators as well as transmission lines. The CMELDC(composite power system effective load duration curve) based on the new effective load model at HLll(Hierarchical Level H) has been developed also. The CMELDC can be obtained from convolution integral processing of the outage capacity probabilistic distribution function of the fictitious generator and the original load duration curve given at the load point. It is expected that the new model for the CMELDC proposed in this study will provide some solutions to many problems based on nodal and decentralized operation and control of an electric power systems under competition environment in future. The CMELDC based on the new model at HLll will extend the application areas of nodal probabilistic production cost simulation, outage cost assessment and reliability evaluation etc. at load points. The characteristics and effectiveness of this new model are illustrated by a case study of MRBTS(Modified Roy Billinton Test System).

• 대한전기학회논문지:전력기술부문A
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• 제48권5호
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• pp.508-516
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• 1999

This paper presents a method for constructing composite power system effective load duration curves(CMELDC) at load points by Monte Carlo method. The concept of effective load duration curves(ELDC) in power system planning is useful and important in both HLII. CMELDC can be obtained from convolution integral processing of the probability function of unsupplied power and the load duration curve at each load point. This concept is analogy to the ELEC in HLI. And, the reliability indices (LOLP, EDNS) for composite power system are evaluated using CMELDC. Differences in reliability levels between HLI and HLII come from considering with the uncertainty associated with the outages of the transmission system. It is expected that the CMELDC can be applied usefully to areas such as reliability evaluation, probabilistic production cost simulation and analytical outage cost assessment, etc. in HLII, DC load flow and Monte Carlo method are used for this study. The characteristics and effectiveness of thes methodology are illustrated by a case study of the IEEE RTS.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.447-450
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• 2005

Multi-channel artificial reverberation algorithm to control perceived direction and distance is described in this paper. In conventional algorithms using IIR filters, reverberation time is the only parameter to be controlled. Moreover, since the convolution-based conventional algorithms apply only same impulse responses, but not considering sound localization, it was not realistic enough. The new algorithm proposed in this paper utilizes early reflections segmented according to the azimuth from which direct sound comes and controls perceived direction by panning the direct sound, and controls perceived distance by adjusting Energy Decay Curve (EDC) of reverberation and gain of the direct sound. In addition, the algorithm enhances Listener Envelopment(LEV) to make late reverberation incoherent among channels.

• 대한전기학회논문지:전력기술부문A
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• 제51권9호
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• pp.425-432
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• 2002

This Paper illustrates a method for evaluating nodal probabilistic production cost using the CMELDC. A new method for constructing CMELDC(CoMposite Power System Equivalent Load Duration Curve) has been developed by authors. The CMELDC can be obtained by convolution integral processing between the probability distribution functions of the fictitious generators outage capacity and the load duration curves at each load point. In general, if complex operating conditions are involved and/or the number of severe events is relatively large, Monte Carlo methods are more efficient. Because of that reason, Monte Carlo Methods are applied for the construction of CMELDC in this study. And IEEE-RTS 24 buses model is used as our case study with satisfactory results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.206-209
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• 2001

This paper illustrates a new method for reliability evaluation at load points in a composite power system. The algorithm includes uncertainties of generators and transmission lines as well as main transformers at substations. The CMELDC based on the new effective load model at HLII has been developed also. The CMELDC can be obtain from convolution integral processing of the outage capacity probabilistic distribution function of the fictitious generator and the original load duration curve given at the load point. The CMELDC based on the new model at HLII will extend the application areas of nodal probabilistic production cost simulation, outage cost assessment and reliability evaluation etc. at load points. The characteristics and effectiveness of this new model are illustrated by a case study of a small test system.

• 한국전산구조공학회논문집
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• 제23권5호
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• pp.525-533
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• 2010

Newmark방법과 같은 직접시간적분법은 시간증분 구간 사이에서 하중이 변하더라도 하중값을 그 시간 구간에서 일정한 하중으로 사용하기 때문에 일정진폭하중과 같은 연속적인 하중함수를 불연속적인 하중함수로 가정하고 수치계산을 수행한다. 따라서 이러한 하중함수의 근사에 따른 오차로 인하여 정확한 수치결과를 계산할 수 없다. 이에 반해, Gurtin의 변분식 에 기초한 유한요소방정식은 하중함수를 시간이력에 대하여 합성적분하여 계산한다. 따라서 시간증분 구간에서 하중이 변하더라도 연속적인 하중함수의 곡선을 따라 가면서 계산하기 때문에 신뢰할 수 있는 수치결과를 구할 수 있다. 본 논문에서는 1차원 막대의 자유단에서 일정진폭하중을 받는 문제를 수치해석하여 Gurtin방법이 Newmark방법 보다 일정진폭하중을 받는 문제에 더 적합한 방법임을 보인다. 또한, Gurtin방법이 일정한 하중을 받는 문제보다 일정진폭하중을 받는 문제에 더 효과적인 방법임을 보인다. Gurtin방법을 FORTRAN으로 프로그래밍하여 해석한 수치결과와 해석용 소프트웨어인 ADINA의 Newmark방법에 의한 수치결과를 비교하여 제시된 수치해의 정확성과 타당성을 검증한다.

• 한국멀티미디어학회논문지
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• 제20권8호
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• pp.1321-1329
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• 2017

A quantum computer, based on quantum mechanics, is a paradigm of information processing that can show remarkable possibilities of exponentially improved information processing. This paradigm can be solved in a short time by calculating factoring problem and discrete logarithm problem that are typically used in public key cryptosystems such as RSA(Rivest-Shamir-Adleman) and ECC(Elliptic Curve Cryptography). In 2013, Lei et al. proposed a secure NTRU-based key distribution protocol for quantum computing. However, Lei et al. protocol was vulnerable to man-in-the-middle attacks. In this paper, we propose a NTRU(N-the truncated polynomial ring) key distribution protocol with mutual authentication only using NTRU convolution multiplication operation in order to maintain the security for quantum computing. The proposed protocol is resistant to quantum computing attacks. It is also provided a secure key distribution from various attacks such as man-in-the middle attack and replay attack.