• 물과 미래
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• 제7권2호
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• pp.107-111
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• 1974

Annual runoff in the Nakdong river basin has been analyzed to find the probability functions of best fit to distribution of historical annual runoff. The results obtained are as follows; (1) Log-normal 3-parameter disrtibution is believed as the probability function of best fit to historical distribution (2) Log-normal 3-parameter disrtibution is believed as the best fit probability function among Log-normal dist-ributions. (3) In the test of goodness of fit, $x^2-test$ shows that probability of $x^2-valus$ in Log-normal 3-parameter distribution is nearly more than 90%. But in the Simirnov-Kolmogorov test, hypotheses for the probability distributions cannot be rejected at significance level 5% & 1%. (4) Among 7 gauging stations, Dongchon & Koryung-Bridge's records show lower fitness to the theoretical probability functions than other 5 gauging station's

• 한국도로학회논문집
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• 제19권6호
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• pp.183-190
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• 2017

PURPOSES : The objective of this study is to establish the traffic volume-based warrants of right-turn lanes at unsignalized intersections and to introduce a risk probability methodology based on the warrants. METHODS : In this study, a risk probability of a potential rear-end collision is applied between a right-turn vehicle and the immediately following through vehicle. Using the shifted negative exponential model and the compound probability theorem, the risk probability can be expressed as the function of directional volumes and the percentage of right-turns for a two-lane and four-lane highway, respectively. RESULTS : Based on the risk probablity, guidelines for installing right-turn lanes on two-lane and four-lane highways were developed. The risk probability also showed rationality by comparing with right-turn same-direction conflicts observed in-situ. CONCLUSIONS : The results of our study define the total approaching volumes to encourage a right-turn lane as a function of operating speed, percentage of right-turn, and number of lanes.

• 대한토목학회논문집
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• 제30권5A호
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• pp.425-431
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• 2010

2가지 이상의 재료로 구성된 다상(multi-phase) 재료는 상 분포에 따라 재료 특성이 다르기 때문에, 상 분포를 묘사할 수 있는 적절한 방법이 필요하다. 본 연구에서는 확률 분포 함수 two-point correlation function과 lineal-path function을 사용하여 재료 내부의 상 분포 상태를 확률적으로 묘사하였다. 수치 계산 방법으로 계산되는 확률 분포 함수를 3개의 매개 변수를 사용한 곡선 접합(curve fitting)을 이용하여 수식으로 표현하고, 적용성을 살펴보기 위하여 2상 합금 미세구조 가상 시편과 지반 모델 시편을 사용하였다. 이를 통해, 확률 분포 함수는 곡선 접합을 이용하여 지수 형태의 수식으로 표현이 가능하며, 이는 시편의 RVE로서의 활용 가능성을 판단하는데 사용될 수 있음을 확인하였다.

• Structural Engineering and Mechanics
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• 제38권5호
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• pp.651-674
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• 2011

This paper presents a novel method for predicting the failure probability of structural or mechanical systems subjected to random loads and material properties involving multiple design points. The method involves Multicut High Dimensional Model Representation (Multicut-HDMR) technique in conjunction with moving least squares to approximate the original implicit limit state/performance function with an explicit function. Depending on the order chosen sometimes truncated Cut-HDMR expansion is unable to approximate the original implicit limit state/performance function when multiple design points exist on the limit state/performance function or when the problem domain is large. Multicut-HDMR addresses this problem by using multiple reference points to improve accuracy of the approximate limit state/performance function. Numerical examples show the accuracy and efficiency of the proposed approach in estimating the failure probability.

• 제어로봇시스템학회논문지
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• 제20권8호
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• pp.854-867
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• 2014

This paper deals with the performance comparison of a PSO algorithm inspired in the process of simulating the behavior pattern of the organisms. The PSO algorithm finds the optimal solution (fitness value) of the objective function based on a stochastic process. Generally, the stochastic process, a random function, is used with the expression related to the velocity included in the PSO algorithm. In this case, the random function of the normal distribution (Gaussian) or uniform distribution are mainly used as the random function in a PSO algorithm. However, in this paper, because the probability distribution which is various with 2 shape parameters can be expressed, the performance comparison of a PSO algorithm using the beta probability distribution function, that is a random function which has a high degree of freedom, is introduced. For performance comparison, 3 functions (Rastrigin, Rosenbrock, Schwefel) were selected among the benchmark Set. And the convergence property was compared and analyzed using PSO-FIW to find the optimal solution.

• Structural Engineering and Mechanics
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• 제28권4호
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• pp.373-386
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• 2008

In this study stochastic analysis of non-linear dynamical systems under ${\alpha}$-stable, multiplicative white noise has been conducted. The analysis has dealt with a special class of ${\alpha}$-stable stochastic processes namely sub-Gaussian white noises. In this setting the governing equation either of the probability density function or of the characteristic function of the dynamical response may be obtained considering the dynamical system forced by a Gaussian white noise with an uncertain factor with ${\alpha}/2$- stable distribution. This consideration yields the probability density function or the characteristic function of the response by means of a simple integral involving the probability density function of the system under Gaussian white noise and the probability density function of the ${\alpha}/2$-stable random parameter. Some numerical applications have been reported assessing the reliability of the proposed formulation. Moreover a proper way to perform digital simulation of the sub-Gaussian ${\alpha}$-stable random process preventing dynamical systems from numerical overflows has been reported and discussed in detail.

• 한국전자통신학회논문지
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• 제12권6호
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• pp.1027-1034
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• 2017

본 논문은 양자게이트의 모든 제어 동작점에서 양자들의 확률진폭, 확률, 평균 기댓값 및 정상상태 단위행렬의 행렬요소 등을 수학적 투사로 측정할 수 있는 새로운 함수 임베딩 방법을 제안하였다. 본 논문의 함수 임베딩 방법은 디랙 기호와 크로네커델타 기호를 사용해 각 제어 동작점에 대한 확률진폭의 직교 정규화조건을 2진 스칼라 연산자에 임베딩 한 것이다. 이와 같은 함수 임베딩 방법은 양자게이트 함수를 단일양자들의 텐서 곱으로 표현하는 유니터리 변환에서 유니터리 게이트의 산술 멱함수 제어에 매우 효과적 수단임을 밝혔다. Ternary 2-qutrit cNOT 게이트에 본 논문이 제안한 함수 임베딩 방법을 적용했을 때의 진화연산과 투사측정 결과를 제시하고, 기존의 방법들과 비교 검토하였다.

• 한국안전학회지
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• 제18권1호
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• pp.116-122
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• 2003

몬테칼로법은 복잡한 특히 비선형문제를 푸는데 강력한 공학도구중의 하나이다. 이 방법은 컴퓨터에서의 통계적인 표본추출방법을 이용하여 각종 공학적인 문제에 근사적인 해를 준다. 교량 하나의 요소나 전체교량의 시간 의존적 파괴확률을 예측하는 방법중의 하나로 생애함수가 있다. 이 논문에서는 교량의 요소나 전체 교량의 파괴확률을 예측하기 위하여, 시스템 신뢰성과 생애함수를 이용하여 포트란 프로그램을 개발하였다. 몬테칼로법은 생애함수의 매개변수를 생성하는데 이용되었다. 적용례로서, 개발된 프로그램은 콘크리트-강 합성 교량에 적용되어, 파괴확률을 예측하는데 이용되었다.

• 한국물환경학회지
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• 제24권3호
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• pp.345-353
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• 2008

In order to design storage-based non-point source management facilities, the aspect of statistical features of the entire precipitation time series should be considered since non-point source pollutions are delivered by continuous rainfall runoffs. The 3-parameter mixed exponential probability density function instead of traditional single-parameter exponential probability density function is applied to represent the probabilistic features of long-term precipitation time series and model urban stormwater runoff. Finally, probability density functions of water quality control basin overflow are derived under two extreme intial conditions. The 31-year continuous precipitation time series recorded in Busan are analyzed to show that the 3-parameter mixed exponential probability density function gives better resolution.

• 대한기계학회논문집
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• 제18권4호
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• pp.1039-1049
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• 1994

The intermitternt and transient fuel spray have been investigated from the simultaneous measurement of droplet sizes and velocities by using Phase/Doppler Particle Analyzer(PDPA). Measurement have been done on the spray axis and at the edge of the spray near nozzle at various gas-to-liquid density ratios(.rho./sub g//.rho./sub l/) that ranges from those found in free atmospheric jets to conditions typical of diesel engines. Probability density distributions of the droplet size and velocity were obtained from raw data and mathematical probability density functions which can fit the experimental distribations were extracted using the principle of maximum likelihood. In the near nozzle region on the spray axis, droplet sizes ranged from the lower limit of the measurement system to the order of nozzle diameter for all (.rho./sub g/ /.rho./sub l/) and droplet sizes tended to be small on the spray edge. At the edge of spray, average droplet velocity peaked during needle opening and needle closing. The rms intensity is greatly incresed as the radial distance from the nozzle is increased. The probability density function which can best fit the physical breakage process such as breakup of fuel drops is exponecially decreasing log-hypebolic function with 4 parameters.