• Journal of electromagnetic engineering and science
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• 제6권4호
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• pp.197-202
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• 2006

This paper presents a study on the differential signaling for the rectangular power-bus structure. The full-wave modal analysis method analyzes how the differential-signaling can lower the power-bus resonance noise levels. The methodology is validated by the use of the FDTD method and reference measurements.

• KIEE International Transactions on Power Engineering
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• 제4A권3호
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• pp.146-151
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• 2004

The most widely used primary protection for the internal fault detection of the power transformer is current ratio differential relaying (CRDR) with harmonic restraint. However, the second harmonic component could be decreased by magnetizing inrush when there have been changes to the material of the iron core or its design methodology. The higher the capacitance of the high voltage status and underground distribution, the more the differential current includes the second harmonic during the occurrence of an internal fault. Therefore, the conventional second harmonic restraint CRDR must be modified. This paper proposes a numerical algorithm for enhanced power transformer protection. This algorithm enables a clear distinction regarding internal faults as well as magnetizing inrush and steady state. It does this by analyzing the RMS fluctuation of terminal voltage, instantaneous value of the differential current, RMS changes, harmonic component analysis of differential current, and analysis of flux-differential slope characteristics. Based on the results of testing with WatATP99 simulation data, the proposed algorithm demonstrated more rapid and reliable performance.

• 정보처리학회논문지C
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• 제18C권4호
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• pp.213-216
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• 2011

차분전력공격(Differential Power Analysis, DPA)의 효율성은 수집신호 정렬도를 비롯한 다양한 잡음에 많은 영향을 받는다. 최근에 Ryoo등은 잡음 신호를 극복하여 DPA의 분석성능 향상을 가져오는 효과적인 신호처리기법을 소개했다. 본 논문에서는 기존에 제안된 신호처리기법이 적용되지 않은 경우를 보이고, 이에 대한 해결방안으로 차분파형모델(Differential Trace Model, DTM)을 제안한다. 또한 제안된 DTM이 DPA 분석에 적합한가에 대해 이론적으로 증명하고 실험을 통해 검증한다.

• 한국정밀공학회지
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• 제21권4호
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• pp.170-178
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• 2004

Continuously variable transmission (CVT) mechanisms considered here are input coupled types that combine the functions of a 2K-H II type differential gear and a V-belt type continuously variable unit (CVU). For the 8 different mechanisms, 4 of them are power-circulation modes while the other 4 are power-split modes, various performance analysis (speed ratios, power flows, divisions of power transmission in a differential gear and a CVU, and theoretical efficiencies) are performed to vary design parameters. Experimental studies are executed to validate fundamental relations (speed ratios, power flows, efficiencies, occurrence of geared neutral). Some useful characteristics associated with performance also are discussed in the mechanisms.

• 대한기계학회논문집B
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• 제27권7호
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• pp.938-947
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• 2003

In this paper, we derived the formula for estimating the power of the electric motors needed to operate the Decanter-type centrifuge. In the derivation of the formula the sludge-removal torque is to be supplied from the formula derived in the first paper. The intricate nature of the transmission mechanism in the planetary gear trains of the sludge-removal power and torque has been clarified in this second paper. In particular we considered two-motor system, where the main motor drives the machine while the differential-speed control motor plays the role of braking in adjusting the differential speed. Sample calculation for the specific design treated in the first paper showed that the selection criterion for the main motor depends on the lower limit of the differential speed; when the lower limit is set low, it should be selected based on the steadily operating power, while it should be selected based on the starting power when the lower limit is set high. The total power required by both the main motor and the differential-speed control motor increases as the differential speed is decreased. It is suggested that the power loss in the differential-speed control motor could be minimized by attaching an electric generator to it.

• 정보보호학회논문지
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• 제20권4호
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• pp.109-115
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• 2010

차분 전력 분석(Differential Power Analysis, DPA) 기법은 암호화 과정 중 발생하는 누설정보를 이용하는 효과적인 부채널 공격(side-channel attack, SCA) 종의 하나로 알려져 있다. 그러나 공격에 사용되는 누설 전력 신호에는 암호화와 관련이 없는 동작에 의해 야기된 전력 신호가 함께 포함되어 있으며, 이로 인해 공격의 효율성이 크게 저하된다. 따라서 본 논문에서는 차분 전력 분석 기법의 공격 성능을 향상시키기 위해, 측정된 전력 신호로부터 암호화 과정에 관련된 부분만을 추출하는 전처리 방법을 제안한다. 모의실험 결과를 통해 제안된 전처리 방법을 적용한 차분 전력 분석 공격은 기존의 차분 전력 분석 공격에 비해 매우 적은 수의 누설 전력 신호만으로도 암호화 알고리즘에 사용된 비밀 키를 찾을 수 있음을 보인다.

• Journal of Power Electronics
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• 제19권5호
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• pp.1289-1302
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• 2019

In this paper, an optimal allocation method of a hybrid active power filter in an active distribution network is designed based on the differential evolution algorithm to resolve the harmonic generation problem when a distributed generation system is connected to the grid. A distributed generation system model in the calculation of power flow is established. An improved back/forward sweep algorithm and a decoupling algorithm are proposed for fundamental power flow and harmonic power flow. On this basis, a multi-objective optimization allocation model of the location and capacity of a hybrid filter in an active distribution network is built, and an optimal allocation scheme of the hybrid active power filter based on the differential evolution algorithm is proposed. To verify the effect of the harmonic suppression of the designed scheme, simulation analysis in an IEEE-33 nodes model and an experimental analysis on a test platform of a microgrid are adopted.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.155-158
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• 2008

In 1989, Kocher et al. introduced Differential Power Attack on block ciphers. This attack allows to extract secret key used in cryptographic computations even if these are executed inside tamper-resistant devices such as smart card. Since 1989, many papers were published to improve resistance of DPA. At FSE 2003 and 2004, Akkar and Goubin presented several masking methods to protect iterated block ciphers such as DES against Differential Power Attack. The idea is to randomize the first few and last few rounds(3 $\sim$ 4 round) of the cipher with independent random masks at each round and thereby disabling power attacks on subsequent inner rounds. This paper show how to combine truncated differential cryptanalysis applied to the first few rounds of the cipher with power attacks to extract the secret key from intermediate unmasked values.

• ETRI Journal
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• 제38권2호
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• pp.387-396
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• 2016

This paper introduces a new type of collision attack on first-order masked Advanced Encryption Standards. This attack is a known-plaintext attack, while the existing collision attacks are chosen-plaintext attacks. In addition, our method requires significantly fewer power measurements than any second-order differential power analysis or existing collision attacks.

• 정보보호학회논문지
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• 제15권1호
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• pp.99-107
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• 2005

ARIA는 128비트 블록 암호 알고리즘으로 128, 192, 256 비트 암호키를 사용한다. 또한 SPN (Substitution and Permutation encryption Network) 구조와 Involution 이진 행렬을 사용하여 초경량 환경 및 하드웨어 구현에 최적으로 개발되었다. 본 논문에서는 실제 스마트카드에 부주의한 ARIA 구현이 차분 전력 분석 공격 (Differential Power Analysis)에 취약함을 널이고자 한다. ARIA에 적용된 공격시점은 S-box 출력에 대한 소비 전력이며 이는 매우 현실적이며 위협적이다. 또한 두 개의 라운드 키만을 이용하여 ARIA의 master key (MK)를 얻을 수 있다.