• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.203-206
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• 2005

본 연구에서는 카오스 2중 Tent 사상에 의한 랜덤 주파수 캐리어 발생기를 제안하고 있다. 제안된 방법은 2중 텐트사상의 분기트리(Bifurcation Tree)에서 카오스 발생 영역인 $\lambda$=0.99을 이용하여 랜덤 수글 발생시키고 있다. 제안된 방법과 종전의 LCG(Linear Congruential Generator)에 의한 방법의 고조파 스펙트럼을 실험에 의하여 비교 검토하였다.

• Industrial Engineering and Management Systems
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• v.15 no.2
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• pp.131-142
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• 2016

We consider a multi-server queueing system without buffer and with two types of customers as a model of operation of a mobile network cell. Customers arrive at the system in the marked Markovian arrival flow. The service times of customers are exponentially distributed with parameters depending on the type of customer. A part of the available servers is reserved exclusively for service of first type customers. Customers who do not receive service upon arrival, can make repeated attempts. The system operation is influenced by random factors, leading to a change of the system parameters, including the total number of servers and the number of reserved servers. The behavior of the system is described by the multi-dimensional Markov chain. The generator of this Markov chain is constructed and the ergodicity condition is derived. Formulas for computation of the main performance measures of the system based on the stationary distribution of the Markov chain are derived. Numerical examples are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.5
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• pp.501-507
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• 2005

This paper proposes a Hybrid Random PWM(HRPWM) technique using a LF2407 DSP board in order to spread the power spectra of an induction motor. The proposed method is composed to the PRBS (Pseudo-Random Binary Sequence) with the Lead-Lag random bit and the random triangular carrier for the logical comparison. Also, a DSP generates the random number, the PRBS and the three-phase reference signal, a MAX038 chip operating as frequency modulator generates the random triangular carrier. For verification of the proposed method, the experiments were conducted with a three-phase adjustable speed a.c drives, and the results of simulations and experiments are presented.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.564-581
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• 2016

We present an efficient hardware prime generator that generates a prime p by combining trial division and Fermat test in parallel. Since the execution time of this parallel combination is greatly influenced by the number k of the smallest odd primes used in the trial division, it is important to determine the optimal k to create the fastest parallel combination. We present probabilistic analysis to determine the optimal k and to estimate the expected running time for the parallel combination. Our analysis is conducted in two stages. First, we roughly narrow the range of optimal k by using the expected values for the random variables used in the analysis. Second, we precisely determine the optimal k by using the exact probability distribution of the random variables. Our experiments show that the optimal k and the expected running time determined by our analysis are precise and accurate. Furthermore, we generalize our analysis and propose a guideline for a designer of a hardware prime generator to determine the optimal k by simply calculating the ratio of M to D, where M and D are the measured running times of a modular multiplication and an integer division, respectively.

• Journal of the Korea Society of Computer and Information
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• v.8 no.4
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• pp.104-110
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• 2003

In this paper, we proposed hybrid cryptosystem of Diffie-Hellman base in Elliptic Curve, and explained for specific protocol design. The proposed system is efficient hybrid cryptosystems system that offer implicit key authentication about sender and receiver unlike existing hybrid system. This system increased safety generating session key using pseudo-random number generator by cryptographic. Because the system is hybrid system, it is more efficient in calculation amount aspect supplementing merit and fault of public key system and secret key system. Also, the system can not get right plaintext except receiver even if sender's secret key is revealed and impersonation attack is impossible. And the system offers security on known keys without influencing in safety of other session's cryptogram even if session key is exposed. And the system is provided safety about mutual entity authentication and replay attack.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.1
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• pp.73-84
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• 1986

A statistical method is proposed which estimates an edge that is one of the basic features in image understanding. The conventional edge detection techniques are performed well for a deterministic singnal, but are not satisfactory for a statistical signal. In this paper, we use the likelihood function which takes account of the statistical property of a signal, and derive the decision function from it. We propose the maximum likelihood edge detection technique which estimates an edge point which maximizes the decision function mentioned above. We apply this technique to statistecal signals which are generated by using the random number generator. Simnulations show that the statistical edge detection technique gives satisfactory results. This technique is extended to the two-dimensional image and edges are found with a good accuracy.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.3
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• pp.3-8
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• 2008

Ephemeral data are easily revealed if state specific information is stored in insecure memory or a random number generator is corrupted. In this letter, we show that Nam et al.'s group key agreement scheme, which is an improvement of Bresson et al.'s scheme, is not secure against session-state reveal attacks. We then propose an improvement to fix the security flaw.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.3
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• pp.61-72
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• 2009

To guarantee security between the tag and back-end server and implementation efficiency in low power tag, we propose two typed mutual authentication protocols in RFID system. One is static-ID authentication scheme which is well suitable in distributed server environments. The other is dynamic-ID scheme which is additively satisfied forward security. In proposed scheme, it does not need any random number generator in tag and requires only one(maximally three) hash operation(s) in tag or server to authenticate each other. Furthermore, we implement the proposed schemes in RFID smart card system and verify its normal operations.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.319-324
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• 1996

Using random pulse stream, a number can be transformed to the pulse stream with the probability value. So the digital value are computed by simple digital gates. Thus it will be possible to build a small and strong noise immunity processing element. We propose a faster convergence algorithm using a new methods for better performance of Random Number Generator(RNG) an the nonlinear transfer function(Sigmoid function)in this paper. And a feedback circuit were fitted for pulse stream in this paper. We proposed method is simulated with C program language and conformed by circuit implementation. Finally a system for hand written number recognition is constructed by FPGA and its performance verified.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1C
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• pp.112-121
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• 2002

In this paper, we present a design of a hash processor for data security systems. Two standard hash algorithms, Sha-1(American) and HAS-1600(Korean), are implemented on a single hash engine to support real time processing of the algorithms. The hash processor can also be used as a PRNG(Pseudo-random number generator) by utilizing SHA-1 hash iterations, which is being used in the Intel software library. Because both SHA-1 and HAS-160 have the same step operation, we could reduce hardware complexity by sharing the computation unit. Due to precomputation of message variables and two-stage pipelined structure, the critical path of the processor was shortened and overall performance was increased. We estimate performance of the hash processor about 624 Mbps for SHA-1 and HAS-160, and 195 Mbps for pseudo-random number generation, both at 100 MHz clock, based on Samsung 0.5um CMOS standard cell library. To our knowledge, this gives the best performance for processing the hash algorithms.