• 대한수학회지
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• 제23권2호
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• pp.167-173
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• 1986

• Structural Engineering and Mechanics
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• 제33권6호
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• pp.675-696
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• 2009

In this paper, a unified solution method is presented for the classical beam theory. In Strength of Materials approach, the geometry, material properties and load system are known and related with the unknowns of forces, moments, slopes and deformations by applying a classical differential analysis in addition to equilibrium, constitutive, and kinematic laws. All these relations are expressed in a unified formulation for the classical beam theory. In the special case of simple beams, a system of four linear ordinary differential equations of first order represents the general mechanical behaviour of a straight beam. These equations are solved using the numerical differential quadrature method (DQM). The application of DQM has the advantages of mathematical consistency and conceptual simplicity. The numerical procedure is simple and gives clear understanding. This systematic way of obtaining influence line, bending moment, shear force diagrams and deformed shape for the beams with geometric and load discontinuities has been discussed in this paper. Buckling loads and natural frequencies of any beam prismatic or non-prismatic with any type of support conditions can be evaluated with ease.

• IEIE Transactions on Smart Processing and Computing
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• 제4권4호
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• pp.291-296
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• 2015

This paper describes the design of a high-speed comparator for high-speed automatic test equipment (ATE). The normal comparator block, which compares the detected signal from the device under test (DUT) to the reference signal from an internal digital-to-analog converter (DAC), is composed of a rail-to-rail first pre-amplifier, a hysteresis amplifier, and a third pre-amplifier and latch for high-speed operation. The proposed continuous comparator handles high-frequency signals up to 800MHz and a wide range of input signals (0~5V). Also, to compare the differences of both common signals and differential signals between two DUTs, the proposed differential mode comparator exploits one differential difference amplifier (DDA) as a pre-amplifier in the comparator, while a conventional differential comparator uses three op-amps as a pre-amplifier. The chip was implemented with $0.18{\mu}m$ Bipolar CMOS DEMOS (BCDMOS) technology, can compare signal differences of 5mV, and operates in a frequency range up to 800MHz. The chip area is $0.514mm^2$.

• 정보보호학회논문지
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• 제24권6호
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• pp.1117-1127
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• 2014

차분 오류 공격(Differential Fault Analysis)은 블록 암호 알고리즘의 안전성 분석에 널리 사용되는 부채널 기법 중 하나이다. 차분 오류 공격은 대표적인 블록 암호인 DES, AES, ARIA, SEED와 경량 블록 암호인 PRESENT, HIGHT 등에 적용되었다[1,2,3,4,5,6]. 본 논문에서는 최근 주목 받고 있는 국내 경량 블록 암호 LEA(Lightweight Encryption Algorithm)에 대한 차분 오류 공격을 최초로 제안한다. 본 논문에서 제안하는 LEA에 대한 차분 오류 공격은 300개의 선택적 오류 주입 암호문을 이용하여 $2^{35}$의 시간 복잡도로 128 비트 마스터키 전체를 복구한다. 본 연구의 실험 결과, Intel Core i5 CPU, 메모리 8 GB의 일반 PC 환경에서 수집한 오류 주입 암호문을 이용하여, 평균 40분 이내에 마스터 키를 찾을 수 있음을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.3810-3830
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• 2015

In this paper, we investigate the differential game theoretic approach for distributed dynamic cooperative power control in cognitive radio ad hoc networks (CRANETs). First, a payoff function is defined by taking into consideration the tradeoff between the stock of accumulated power interference to the primary networks and the dynamic regulation of the transmit power of secondary users (SUs). Specifically, the payoff function not only reflects the tradeoff between the requirement for quickly finding the stable available spectrum opportunities and the need for better channel conditions, but also reveals the impact of the differentiated types of data traffic on the demand of transmission quality. Then the dynamic power control problem is modeled as a differential game model. Moreover, we convert the differential game model into a dynamic programming problem to obtain a set of optimal strategies of SUs under the condition of the grand coalition. A distributed dynamic cooperative power control algorithm is developed to dynamically adjust the transmit power of SUs under grand coalition. Finally, numerical results are presented to demonstrate the effectiveness of the proposed algorithm for efficient power control in CRANETs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권2호
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• pp.600-616
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• 2021

SIMON and SPECK are two families of lightweight block ciphers that have excellent performance on hardware and software platforms. At CRYPTO 2019, Gohr first introduces the differential cryptanalysis based deep learning on round-reduced SPECK32/64, and finally reduces the remaining security of 11-round SPECK32/64 to roughly 38 bits. In this paper, we are committed to evaluating the safety of SIMON cipher under the neural differential cryptanalysis. We firstly prove theoretically that SIMON is a non-Markov cipher, which means that the results based on conventional differential cryptanalysis may be inaccurate. Then we train a residual neural network to get the 7-, 8-, 9-round neural distinguishers for SIMON32/64. To prove the effectiveness for our distinguishers, we perform the distinguishing attack and key-recovery attack against 15-round SIMON32/64. The results show that the real ciphertexts can be distinguished from random ciphertexts with a probability close to 1 only by 2^8.7 chosen-plaintext pairs. For the key-recovery attack, the correct key was recovered with a success rate of 23%, and the data complexity and computation complexity are as low as 2⁸ and 2^20.1 respectively. All the results are better than the existing literature. Furthermore, we briefly discussed the effect of different residual network structures on the training results of neural distinguishers. It is hoped that our findings will provide some reference for future research.

• 영어어문교육
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• 제12권4호
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• pp.211-234
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• 2006

The purpose of the present study was to investigate how two types of cooperative groupworks will affect learners' academic self-efficacy and English achievement in the first graders of Middle school. Experimental class A was done by similar-level groupwork, experimental class B by differential-level groupwork, and controlled class C by whole classwork. In order to accomplish the goals of the study, questionnaires on learners' academic self-efficacy were examined before and after the experiment. Also English achievement tests were done during the experiment. The analytic results of the questionnaires and English achievement tests were like the following conclusions: First, two types of cooperative groupworks were more effective on improving learners' academic self-efficacy than the whole classwork. Second, two types of cooperative groupworks were more effective on improving two levels' (higher and medium) academic self-efficacy. Third, among three types of classworks, differential-level groupwork was the most effective on improving learners' English achievement. Fourth, in case of medium-level learners, differential-level groupwork was more effective on improving their English achievement than similar-level groupwork.

• 한국의류학회지
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• 제19권4호
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• pp.565-579
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• 1995

The purpose of this study was 1) to investigate the effect of male clothing type and facial attractiveness on the subjects' inferences of occupational and appearance characteristics for the wearers. The subjects 'inferences of occupational and appearance characteristics for the wearers were measured by means of semantic-differential scales and open-ended questionnaires. The stimuli were composed of 18 color photographs which were made of 3 levels of facial attractiveness in combination with 6 types of clothing. The subjects were 216 male and 216 female university students. The results were as follows: First, the responses to the semantic-differential scales were factor analyzed to identify the underlying constructs of occupational characteristics. As the result, 4 factors were emerged. The first factor was interpreted to Appearance·Ability, the second, Individuality, the third, Dominance, and the fourth, Naivety. Second, the type of clothing influenced on all the 4 factors, and was more influencial than the facial attractiveness which influenced on the 3 factors except the Naivety factor. Third, There were differences perceptions for the wearers beteen subjects 'sex type; The male subjects perceived for the wearers with categorization more exactly than the female's. Fourth, there were accordances between free-association and inference in semantic-differential scales for the wearers.

• 대한수학회지
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• 제32권3호
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• pp.401-413
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• 1995

This paper is concerned with the problem given below $$ (1.1) i\frac{dx}{du_1(x,\lambda)} + q1(x)u_2(x,\lambda) = \lambdau_1(x,\lambda) 0 \leq x < \infty - i\frac{dx}{du_2(x,\lambda)} + q2(x)u_1(x,\lambda) = \lambdau_2(x,\lambda), $$ $$ (2) u_2(0,\lambda) - hu_1(0,\lambda) = 0 $$ where $\lambda$ is a complex parameter and h is a non-zero complex number.

• 대한수학회보
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• 제48권3호
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• pp.627-636
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• 2011

In this paper, we obtain some applications of first order differential subordination and superordination results for higher-order derivatives of p-valent functions involving certain linear operator. Some of our results improve and generalize previously known results.