• International Journal of Reliability and Applications
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• 제6권2호
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• pp.101-115
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• 2005

This article provides a new class of multivariate linear failure rate distributions where every component is a mixture of linear failure rate distribution. The new class includes several multivariate and bivariate models including Marslall and Olkin type. The approach in this paper is based on the introducing a linear failure rate distributed latent random variable. The distribution of minimum in a competing risk model is discussed.

• 대한수학회지
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• 제32권3호
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• pp.447-459
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• 1995

A fundamental problem is to construct linear systems with given transfer functions. This problem has a well known solution for unitary linear systems whose state spaces and coefficient spaces are Hilbert spaces. The solution is due independently to B. Sz.-Nagy and C. Foias [15] and to L. de Branges and J. Ball and N. Cohen [4]. Such a linear system is essentially uniquely determined by its transfer function. The de Branges-Rovnyak construction makes use of the theory of square summable power series with coefficients in a Hilbert space. The construction also applies when the coefficient space is a Krein space [7].

• International Journal of Reliability and Applications
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• 제10권2호
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• pp.63-79
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• 2009

A new bivariate linear failure rate distribution is introduced through a shock model. It is proved that the marginal distributions of this new bivariate distribution are linear failure rate distributions. The joint moment generating function of the bivariate distribution is derived. Mixtures of bivariate linear failure rate distributions are also discussed. Application to a real data is given.

• 제어로봇시스템학회논문지
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• 제4권5호
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• pp.644-650
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• 1998

In this paper , a state space model for flexible beam is presented using the assumed-modes approach. The state space equation is derived for a flexible beam in which one end is connected to a motor and is driven by a torque equation and the other end is free. Many of the transfer function proposed thus far use the torque to the flexible beam as the input and the tip deflection of the flexible beam as the output. The Technique for the analysis and synthesis of the dual-input describing function(DIDF) is introduced here and the construction of a non-linear compensator, based on this technique, is proposed. This non-linear compensator, properly connected in the direct path of a closed-loop linear or non-linear control system. The above non-linear network is used to compensate linear and non-linear systems for instability, limit cycles, low speed of response and static accuracy. The effectiveness of the proposed scheme is demonstrated through computer simulation and experimental results.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제2권1호
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• pp.43-51
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• 1995

In this paper, we introduce the almost linear spaces, a generalization of linear spaces. We prove that if the almost linear space X has a finite basis then, as in the case of a linear space, the cardinality of bases for the almost linear space X is unique. In the case X = Wx ＋ Vx, we prove that B'= {$\chi$'$_1,...,x'_n} is a basis for the algebraic dual X$^#$ of X if B = {$\chi$'$_1,...,x'_n} is a basis for the almost linear space X. And we have an example X($\neq$Wx ＋ Vx) which has no such a basis.

• ETRI Journal
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• 제32권1호
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• pp.93-101
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• 2010

A true random number generator (TRNG) is widely used to generate secure random numbers for encryption, digital signatures, authentication, and so on in crypto-systems. Since TRNG is vulnerable to environmental changes, a deterministic function is normally used to reduce bias and improve the statistical properties of the TRNG output. In this paper, we propose a linear corrector for secure TRNG. The performance of a linear corrector is bounded by the minimum distance of the corresponding linear error correcting code. However, we show that it is possible to construct a linear corrector overcoming the minimum distance limitation. The proposed linear corrector shows better performance in terms of removing bias in that it can enlarge the acceptable bias range of the raw TRNG output. Moreover, it is possible to efficiently implement this linear corrector using only XOR gates, which must have a suitable hardware size for embedded security systems.

• 전기학회논문지
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• 제62권11호
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• pp.1544-1549
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• 2013

Recently, the linear compressors with the free piston driven by the linear motor have widely attention in the cooling apparatus such as a refrigerator due to high efficiency. The method of using triacs as a linear motor drive is not satisfactory to improve the efficiency of the linear compressor. In this paper, the performance of the linear compressor using a PWM inverter such as the efficiency is investigated with the variations of both mechanical resonant frequency and electrical resonant frequency. The control loop for controlling both the piston stroke and efficiency is suggested. Through simulation and experimental studies, the performance of both the stroke and angle controls for improving the efficiency of the linear compressor is verified.

• ETRI Journal
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• 제39권1호
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• pp.108-115
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• 2017

ARIA is a 128-bit block cipher that has been selected as a Korean encryption standard. Similar to AES, it is robust against differential cryptanalysis and linear cryptanalysis. In this study, we analyze the security of ARIA against differential-linear cryptanalysis. We present five rounds of differential-linear distinguishers for ARIA, which can distinguish five rounds of ARIA from random permutations using only 284.8 chosen plaintexts. Moreover, we develop differential-linear attacks based on six rounds of ARIA-128 and seven rounds of ARIA-256. This is the first multidimensional differential-linear cryptanalysis of ARIA and it has lower data complexity than all previous results. This is a preliminary study and further research may obtain better results in the future.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.785-790
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• 2001

Linear motors can drive a linear motion without intermediate gears, screws or crank shafts. Linear motors can successfully replace ball lead screw in machine tools, because they have a high velocity, acceleration and good positioning accuracy. On the other hand, linear motors emit large amounts of heat and have low efficiency. In this paper, heat sources of a synchronous linear motor with high velocity and force are measured and analyzed. To improve the thermal stiffness of the linear motor, an insulation layer with low thermal conductivity is inserted between cooler and machine table. Some effects of the insulation layer are presented.

• 한국정밀공학회지
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• 제19권3호
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• pp.123-130
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• 2002

Linear motors can drive a linear motion without intermediate gears, screws or crank shafts. Linear motors can successfully replace ball lead screw in machine tools because they have a high velocity, acceleration and good positioning accuracy. On the other hand, linear motors emit large amounts of heat and have low efficiency. In this paper, heat sources of a synchronous linear motor with high velocity and force measured and analyzed. To improve the thermal characteristics of the linear motor, an insulation layer with low thermal conductivity is inserted between cooler and machine table. Some effects of the insulation layer are presented.