• 한국농공학회논문집
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• 제64권2호
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• pp.47-55
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• 2022

The objective of this study was to analyze the effect of the duration and time distribution of probability rainfall on farmland inundation for the paddy fields in the drainage improvement project site. In this study, eight drainage improvement project sites were selected for inundation modeling. Hourly rainfall data were collected, and 20- and 30-year frequency probability rainfalls were estimated for 14 different durations. Probability rainfalls were distributed using Intensity-Duration-Frequency (IDF) and Huff time distribution methods. Design floods were calculated for 48 hr and critical duration, and IDF time distribution and Huff time distribution were used for 48 hr duration and critical duration, respectively. Inundation modeling was carried out for each study district using 48 hr and critical duration rainfalls. The result showed that six of the eight districts had a larger flood discharge using the method of applying critical duration and Huff distribution. The results of inundation depth analysis showed similar trends to those of design flood calculations. However, the inundation durations showed different tendencies from the inundation depth. The IDF time distribution is a distribution in which most of the rainfall is concentrated at the beginning of rainfall, and the theoretical background is unclear. It is considered desirable to apply critical duration and Huff time distribution to agricultural production infrastructure design standards in consideration of uniformity with other design standards such as flood calculation standard guidelines.

• 대한기계학회논문집A
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• 제28권6호
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• pp.739-746
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• 2004

The plastic deformation behavior of an aluminum alloy containing a particle and porosities was investigated at room temperature during equal channel angular pressing (ECAP). Finite element analysis by using ABAQUS shows that ECAP is a useful tool for eliminating residual porosity in the specimen, and more effective under friction condition. The simulation, however, shows considerably low density distributions for matrix near a particle at which many defects may occur during severe deformation. Finite element results of effective strains and deformed shapes for matrix with a particle were compared with theoretical calculations under simple shear stress. Also, based on the distribution of the maximum principal stress in the specimen, Weibull fracture probability was obtained for particle sizes and particle-coating layer materials. The probability was useful to predict the trend of more susceptible failure of a brittle coating layer than a particle without an interphase in metal matrix composites.

• 대한토목학회논문집
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• 제33권5호
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• pp.1731-1740
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• 2013

교량의 내구성과 설계수명 평가에 있어 대형화물차와 같은 중차량의 총중량 크기와 분포 특성은 큰 영향을 미치며, 총중량의 특성은 WIM 시스템에서의 측정 데이터를 활용하여 파악하고 있다. 고속도로상에 설치된 고속 WIM 시스템을 통해 측정된 중차량의 분포를 분석한 결과, 대부분의 중차량은 7종, 10종, 12종 화물차에서 발생하였다. 이들 화물차의 전체적인 총중량 분포와 상위 총중량 분포에 대한 확률분포 모델을 추정하였다. 전체적인 총중량 분포는 정규확률 분포에 근접하는 것으로 분석되었으며, 상위 10% 데이터는 극치분포의 하나인 Weibull 3 확률분포에 가장 높은 적합도를 갖는 것으로 나타났다.

• Journal of Microbiology
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• 제33권2호
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• pp.95-102
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• 1995

A probability identification matrix of acidophilic Streptomyces was constructed. The phenetic data of the strains were derived from numerical classification described by Seong et al. The minimum number of diagnostic characters was determined using computer programs for calculation of different separation indices. The resulting matrix consisted of 25 clusters versus 53 characters. Theoretical evaluation of this matrix was achieved by estimating the chuster overlap and the identification scores for the Hypothetical Median Organisms (HMO) and for the representatives of each cluster. Cluster overlap was found to be relatively small. Identification scores for the HMO and the randomly selected representatives of each cluster were satisfactory. The matrix was assessed practically by applying the matrix to the identification of unknown isolates. Of the unknown isolates, 71.9% were clearly identified to one of eight clusters. The numerical classification data was also used to design a selective isolation medium for antibiotic-producing organisms. Four chemical substances including 2 antibiotics were determined by the DLACHAR program as diagnostic for the isolation of target organisms which have antimicrobial activity against Micrococcus luteus. It was possible to detect the increased rate of selective isolation on the synthesized medium. Theresults show that the numerical phenetic data can be applied to a variety of purposes, such as construction of identification matrix and selective isolation medium for acidophilic antinomycetes.

• 대한기계학회논문집B
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• 제23권9호
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• pp.1172-1177
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• 1999

Comparisons of measured turbulence properties in the unburned gas region of turbulent premixed flame stabilized by pilot flame, in cases of combusting and non-combusting flow conditions, are presented. Methane-air premixed jet at fuel equivalence ratio of 0.6 and 1.0 and Reynolds number of 7,000 was diagnosed using two-color laser velocimeter to obtain turbulence statistics. Same set of measurements was repeated at 21 locations within the unburned gas region of both combusting and non-combusting conditions. Velocity data were analyzed to evaluate the spatial distribution of turbulence properties including Reynolds stress, probability densities, joint probability densities and auto correlations. Contrary to assumptions of current theoretical models, significant influence of flame was observed in every property that was studied in the present investigation. The effective viscosity increased ten-fold when flame was on from cold flow values. The effect of mixing on joint probability as well as in turbulence intensity was suppressed by the flame. The measurements suggest that common assumptions of premixed flame model may result in sizable error in prediction of flame length and temperature distribution in near-field.

• Wind and Structures
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• 제26권4호
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• pp.231-251
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• 2018

The objective of the investigation is the analysis of wind-tunnel experimental errors, associated with the measurement of aeroelastic coefficients of bridge decks (Scanlan flutter derivatives). A two-degree-of-freedom experimental apparatus is used for the measurement of flutter derivatives. A section model of a closed-box bridge deck is considered in this investigation. Identification is based on free-vibration aeroelastic tests and the Iterative Least Squares method. Experimental error investigation is carried out by repeating the measurements and acquisitions thirty times for each wind tunnel speed and configuration of the model. This operational procedure is proposed for analyzing the experimental variability of flutter derivatives. Several statistical quantities are examined; these quantities include the standard deviation and the empirical probability density function of the flutter derivatives at each wind speed. Moreover, the critical flutter speed of the setup is evaluated according to standard flutter theory by accounting for experimental variability. Since the probability distribution of flutter derivatives and critical flutter speed does not seem to obey a standard theoretical model, polynomial chaos expansion is proposed and used to represent the experimental variability.

• 한국군사과학기술학회지
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• 제14권1호
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• pp.123-131
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• 2011

In this paper, modeling and design of a distributed detection system are considered for an active sonar sensor network. The sensor network has a parallel configuration and it consists of a fusion center and a set of receiver nodes. A system with two receiver nodes is considered to investigate a theoretical aspect of design. To be specific, AND rule and OR rule are considered as the fusion rules of the sensor network. For the fusion rules, it is shown that a threshold rule of each sensor node has uniformly most powerful properties. Optimum threshold for each sensor is obtained that maximizes the probability of detection given probability of false alarm. Numerical experiments were also performed to investigate the detection characteristics of a distributed detection system with multiple sensor nodes. The experimental results show how signal strength, false alarm probability, and the distance between nodes in a sensor field affect the system detection performances.

• 응용통계연구
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• 제6권1호
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• pp.145-162
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• 1993

본 논문에서는 반복적 계속 표본조사에서 일부의 표본을 교체하는 2회 계속조사의 표본 추 출법들을 요약하고 앞 조사시기의 관찰값을 확률측도로 이용한 RHC(Rao-Hartley-Cochran) 유형의 불균등 확률추출법을 제안하였다. 제안된 추출법과 기존의 확률추출법의 비교를 위 하여 둘째 조사시기의 모평균 추정량과 그의 분산을 유도하였으며, 제안된 추출법의 상대 효율은 이론적인 측면과 수치적 시뮬레이션 방법으로 비교 분석되었다. 시뮬레이션 비교를 위하여 한 특별한 시계열 모형을 가정하고 이를 사용하여 인위적인 모집단을 생성하였으며 이 모집단에서 각 추출법에 해당되는 표본을 컴퓨터로 추출하여 각각의 추정치를 계산하여 비교한 결과에서 RHC 유형의 새로 제안된 추출법의 분산과 편차가 일반적으로 적음을 보 였다.

• 응용통계연구
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• 제19권1호
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• pp.69-80
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• 2006

본 연구에서는 매우 민감한 조사에서 모집단이 집락의 크기가 서로 다른 여러 개의 집락으로 구성되어 있을 때, 집락의 크기에 비례하게 추출확률을 부여하는 확률비례추출법(probability proportional to size : pps)을 이용한 확률화응답기법을 제안하고자 한다. 민감한 속성에 대한 모수의 추정치와 분산 및 분산추정량을 구하여 이론적 체계를 구축하고, 확률비례추출법에 의한 확률화응답기법과 등확률 2단계 추출법에 의한 확률화응답기법의 효율성을 비교해 보고자 한다. 또한, 실제조사를 통해 제안한 확률비례추출법에 의한 확률화응답기법에 대한 실용화의 타당성을 검토하고자 한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1157-1162
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• 2003

Behavior of aluminum alloy embedding a particle was investigated at room temperature under ECAP. Finite element analysis by using ABAQUS shows that ECAP is a useful tool for eliminating residual porosity in the specimen, and much more effective under friction condition. The simulation, however, shows considerably low density distributions for matrix near a particle at which rich defects may occur during severe deformation. Finite element results of effective strains and deformed shapes for matrix with a particle were compared with theoretical calculations under simple shear stress. Also, based on the distribution of the maximum principal stress in the specimen, Weibull fracture probability was obtained for particle sizes and particle-coating layer materials. The probability was useful to predict the trend of more susceptible failure of a brittle coating layer than a particle without an interphase in metal matrix composites.