• The KIPS Transactions:PartA
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• v.9A no.3
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• pp.295-300
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• 2002

In this paper, we apply the 3-dimension algorithm to the random interleaver and s-random interleaver and analyze the performance of the turbo code system with random interleaver (or s-random interleaver). In general, the performance of interleaver is determined by minimum distance between neighbor data, thus we could improve the performance of interleaver by increasing the distance of the nearest data. The interleaver using 3-dimension algorithm has longer minimum distance and average distance compared to existing random-interleaver (s-random interleaver) because the output data is generated randomly from 3-dimension storage. To verify and compare the performance of our proposed system, the computer simulations have been performed in turbo code system under gaussian noise environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.33-39
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• 2010

Correntropy is a generalized correlation function that contains higher order moments of the probability density function (PDF) than the conventional moment expansions. The criterion maximizing cross-correntropy (MCC) of two different random variables has yielded superior performance particularly in nonlinear, non-Gaussian signal processing comparing to mean squared error criterion. In this paper we propose a new blind equalization algorithm based on cross-correntropy criterion which uses, as two variables, equalizer output PDF and Parzen PDF estimate of a set of randomly generated symbols that complies with the transmitted symbol PDF. The performance of the proposed algorithm based on MCC is compared with the Euclidian distance minimization.

• Annual Conference of KIPS
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• 2012.11a
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• pp.499-502
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• 2012

문양이나 패턴이 없는 민 무늬의 물체에는 동일점 정합에 의해 3 차원 계측을 하는 스테레오 정합방식을 적용할 수 없다. 본 논문에서는 난수 발생 함수로 제작한 랜덤 칼라 패턴을 대상물체에 투영하여, 대상 물체 표면에 특징적인 문양을 인위적으로 생성시키는 것에 의해 민 무늬의 물체를 스테레오 정합법으로 측정하는 방식을 제안한다. 투사된 패턴으로 자체 문양을 지니게 된 물체를 스테레오 카메라로 촬영하였고, 동일점 정합은 전역 스테레오 정합 방식의 일종인 TRW 방식에 의한 컬러 매칭 방식을 사용하였다. 제안된 방식은 원형의 흰색 석고상 3 차원 계측에 적용되었고, 안정적이고 정확한 스테레오 정합 계측 결과를 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4A
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• pp.330-335
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• 2007

This paper proposes a multichannel random access channel allocation scheme for multihop cellular networks to guarantee the stable throughput of a random access. The fundamental contribution is a mathematical formula for an optimal partition ratio of shared random access channels between a base station and a relay station. In addition, the proposed scheme controls the retransmission probability of random access packets under heavy load condition. Simulation results show that the proposed scheme can guarantee the required random access channel utilization and packet transmission delay even if the a random access packet arrival rate is higher than 0.1.

• The Korean Journal of Financial Management
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• v.16 no.2
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• pp.243-261
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• 1999

본 논문은 순이익의 시계열 속성을 조사하고, 순이익의 시계열이 랜덤워크 모형과 일치하는지를 단위근 검증방식을 사용하여 조사하며, 시계열 속성에 근거하여 도출된 예측모형과 흔히 사용되어 온 랜덤워크 모형의 예측능력을 비교하여 선행연구에서 사용되고 있는 랜덤워크 모형에 실증적 타당성을 제시하는 것을 주목적으로 하고 있다. 본 연구는 한국신용평가주식회사의 데이터 베이스에 1980년부터 1996년까지 17년간 자료가 연속적으로 포함되어 있는 금융기업을 제외한 모든 기업(272개)을 표본으로 사용하고 있다. 표본기업의 순이익 시계열에 가장 적합한 과정은 랜덤워크나 AR(1) 또는 AR(2) 모형이다. 또한 본 논문은 대부분의 기업에 때해 순이익이 랜덤워크 과정을 따른다는 가설을 기각할 수 없음을 보였다. 이들 상이한 모형의 표본외 예측력(out-of-sample predictive ability)을 비교한 결과 상수항을 포함한 랜덤워크 모형이 가장 작은 평균 절대 예측오차(mean absolute forecast error)를 갖는 것으로 나타나고 있다. 본 연구는 기존의 연구가 순이익 시계열의 불안정성(nonstationarity) 문제를 무시하거나 명시적으로 다루고 있지 않은 것과는 달리 단위근 검증(unit root test)을 통해 연간 순이익이 대체로 불안정하다는 것을 보였으며, 또한 상이한 모형의 표본외 예측능력을 비교한 결과 선행연구에서 사용하여 온 랜덤워크 모형의 우월성에 대한 실증적 증거를 제공하였다는 데 의의가 있다.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.287-297
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• 1998

RPWM(Random Pulse Width Modulation) is a switching technique to spread the voltage and current harmonics on wide frequency area. Using randomly changed switching frequency of the inverter, the power spectrum of the electromagnetic acoustic noise can be spread into the wide-band area. And the wide-band noise is much more comfortable and less annoying than the narrow-band one. So RPWM have been attracting an interest as an excellent reduction method of acoustic noise on the inverter drive system. In this paper a new RPPWM(Random Position PWM) is proposed and implemented. Each of three pulses is located randomly in each switching intervals. Along with the randomization of PWM pulses, the space vector modulation is processed on the C167 microcontroller also. The experimental results show that the voltage and current harmonics were spread into wide band area and that the audible switching noise was reduced by proposed RPPWM method.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.595-597
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• 2005

청소로봇은 대부분 랜덤방식 또는 바둑판식의 청소알고리즘으로 운용된다. 랜덤 알고리즘은 전체 청소 시간이 오래 걸린다는 단점을 가지고 있다. 랜덤 알고리즘의 문제를 해결하기 위한 바둑판식 알고리즘은 현재까지 가장 좋은 알고리즘으로 알려져 있으나 장애물이 복잡한 공간에서는 청소시간이 길어지는 단점을 가지고 있다. 이런 문제점을 해결하기 위하여 본 논문에서는 Group-k 라는 새로운 청소 알고리즘을 제안한다. Group-k 알고리즘은 청소시간을 단축시키는 목적보다는 청소시간은 같더라도 복잡한 구역일수록 나중에 청소함으로써 가능한 빠른 시간 내에 가장 많은 면적을 청소하는 것을 목표로 한다. 즉 인접한 복잡한 장애물들을 하나의 그룹으로 구성하고 그룹의 복잡성을 계산하여 복잡성이 낮은 그룹부터 먼저 청소하는 방식이다. 시뮬레이션에 기반한 실험을 통해 Group-k 알고리즘이 복잡한 장애물 구역을 그룹화하여 복잡한 공간을 효율적으로 청소함을 보여준다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.1058-1068
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• 2017

In V2X communication, a random based resource selection scheme is needed with considerations of cases that support devices without sidelink reception capabilities and require reduction of UE's power consumption. In this paper, as improvement of D2D's resource section scheme that one TRP is repeated to data subframe pool within a PSCCH period, it is proposed that different TRPs is applied for enhanced random resource selection based on pseudo-random sequence having UE-specific seed value. By results of proposed scheme's performance by numerical analysis, it is confirmed that collision probability among resources allocated to each UE for data TB is reduced, and a number of UEs which can avoid resource collision as much as possible and have simultaneous resource allocation is increased.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1638-1643
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• 2019

In this paper, we propose an adaptive-perturbation-aided opportunistic precoding (APOP) scheme for multiple-input multiple-output (MIMO) systems. To update a precoding matrix in MIMO systems, the proposed algorithm produces a random perturbation in each time slot. Then the additional adaptive perturbation is also applied, which depends on the reports of achievable data-rates from users. If the prior random perturbation increased the data rate, the adaptive perturbation is set to be the same as the prior random perturbation, otherwise the negative value of the prior random perturbation is applied for adaptive perturbation. Furthermore, to enhance the achievable data rates, the information on the stored precoding matrices in the memory as well as the currently generated precoding matrix is used for scheduling. Simulation results show that compared to conventional opportunistic precoding schemes, higher data rates are achieved by the proposed APOP scheme, especially when there are a relatively small number of users.

• 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.