• 응용통계연구
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• 제27권3호
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• pp.397-406
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• 2014

최소밀도함수승간격 추정법은 Baus 등 (1998)에 의해 처음 소개된 이후 많은 관심의 대상이 되었다. 최소밀도함수승간격 추정량은 우수한 로버스트 성질을 갖고 효율성도 최우추정량에 필적한 것으로 알려져 있다. 본 논문에서는 생물정보학에서 사용되는 노말-지수 분포에 근거한 추정량을 최소밀도함수승간격 추정법을 사용하여 구하는 방법을 다루고자 한다. 그런데 그 과정에서 간격을 적분을 통해 구하는 것이 매우 어려움으로 인해 직접적인 적분 대신 라플라스 근사를 시도할 것을 제안한다. 그 결과 추정량이 다소 효율성이 줄어들지만 로버스트 성질을 갖고 있음을 수학적 방법과 모의실험을 통하여 보였다.

• 한국정보과학회논문지:데이타베이스
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• 제35권6호
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• pp.518-532
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• 2008

모바일 환경에서는 상향링크와 하향링크의 대역특이 비대칭적이며 전력이 한정되어 있기 때문에 보다 효율적인 데이타 전송기술인 브로드캐스팅 방법이 연구되어 왔다. 브로드캐스트에서 인덱스를 사용하면 원하는 데이타가 언제 방송되는지를 알 수 있어 튜닝 시간을 줄이고, 전력의 소비를 줄일 수 있다. 지금까지 연구된 싱글 채널 인덱스 기법들은 모든 데이타 아이템이 동일한 확률로 접근되는 flat 브로드캐스트에 적합한 인덱스 기법들이다. 데이타 아이템에 대한 접근 확률이 편향되는 경우에는 멀티디스크 방송기법을 사용해야 효과적인 전송이 가능하나, 기존의 인덱스 기법들은 인덱스가 한 방송 주기 내에서 반복되어 방송되는 데이타 아이템을 가리킬 수 없기 때문에 멀티디스크 방송 기법에는 효과적이지 않다. 본 논문에서는 싱글 채널 인덱스 기법으로서 멀티디스크 방송에 적용되는 인덱스 기법인 MDEI (Multi-disk Exponential Index) 기법을 제안한다. 본 논문에서 제안하는 MDEI 기법은 각 디스크 별로 인덱스를 구성하기 때문에, 데이타에 대한 접근확률이 편향되는 경우에 flat 브로드캐스트를 사용하는 다른 인덱스 기법들보다 평균 접근 지연시간 시간을 크게 줄일 수 있다. 실험 결과는 데이타에 대한 접근 확률이 편향된 환경에서 MDEI가 평균 접근 지연시간에 있어서 매우 좋은 성능을 갖는 것을 보여준다.

• 조명전기설비학회논문지
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• 제29권7호
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• pp.71-79
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• 2015

This paper is on the development of computer software which can be utilized as a power system analysis tool for reliability assessment education. The input data of the developed software are so simple that even a non-expert easily understand how to use it. The software provides not only reliability indices but also their distributions, moreover, it provides the factors those effect the indices, which made the software even more useful for educational purpose. The developed software utilized Monte-carlo simulation based on the state duration sampling, therefore it can manage various probability distributions such as exponential, Weibull, gamma and lognormal distribution. Within the software, the parameters of the distribution can be decided automatically from its mean and variance, that is another advantage as an educational software.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.3630-3656
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• 2018

Degree distribution can provide basic information for structural characteristics and internal relationship in social network. It is a critical procedure for social network topology analysis. In this paper, based on the mean-field theory, we study a special type of social network with exponential distribution of time intervals. First of all, in order to improve the accuracy of analysis, we propose a spreading coefficient algorithm based on intimate relationship, which determines the number of the joined members through the intimacy among members. Then, simulation show that the degree distribution of follows the power-law distribution and has small-world characteristics. Finally, we compare the performance of our algorithm with the existing algorithms, and find that our algorithm improves the accuracy of degree distribution as well as reducing the time complexity significantly, which can complete 29.04% higher precision and 40.94% lower implementation time.

• Wind and Structures
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• 제31권4호
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• pp.299-309
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• 2020

In this study, wind data such as speeds, loads and potential of Muğla which is located in the southwest of Turkey were statistically analyzed. The wind data which consists of hourly wind speed between 2010 and 2013 years, was measured at the 10-meters height in four different ground stations (Datça, Fethiye, Marmaris, Köyceğiz). These stations are operated by The Turkish State Meteorological Service (T.S.M.S). Furthermore, wind data was analyzed by using Log-Normal and Gamma distributions, since these distributions fit better than Weibull, Normal, Exponential and Logistic distributions. Root Mean Squared Error (RMSE) and the coefficients of the goodness of fit (R²) were also determined by using statistical analysis. According to the results, extreme wind speed in the research area was 33 m/s at the Datça station. The effective wind load at this speed is 0.68 kN/㎡. The highest mean power densities for Datça, Fethiye, Marmaris and Köyceğiz were found to be 46.2, 1.6, 6.5 and 2.2 W/㎡, respectively. Also, although Log-normal distribution exhibited a good performance i.e., lower AD (Anderson - Darling statistic (AD) values) values, Gamma distribution was found more suitable in the estimation of wind speed and power of the region.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.29-31
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• 2006

The most crucial requirement of a power system is o supply quality electric energy to customers without interrution. This problem is directly related to reliability of power system. Reliability assessment of power system has been an important topic for the past several decades. This paper deals with reliability assessment of a 154kV power substation n KEPCO. In his paper, exponential distribution is used to calculate reliablity index. The failure rate data that are utilited for reliablity index based on the realistic system. Also, FTA(Fault Tree Analysis) is used to compute substation reliablity

• Structural Engineering and Mechanics
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• 제89권1호
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• pp.1-11
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• 2024

This article introduces a novel analytical model for examining the impact of porosity on shear correction factors (SCFs) in functionally graded porous beams (FGPB). The study employs uneven and logarithmic-uneven modified porosity-dependent power-law functions, which are distributed throughout the thickness of the FGP beams. Additionally, a modified exponential-power law function is used to estimate the effective mechanical properties of functionally graded porous beams. The correction factor plays a crucial role in this analysis as it appears as a coefficient in the expression for the transverse shear stress resultant. It compensatesfor the assumption that the shear strain is uniform across the depth of the cross-section. By applying the energy equivalence principle, a general expression for static SCFs in FGPBs is derived. The resulting expression aligns with the findings obtained from Reissner's analysis, particularly when transitioning from the two-dimensional case (plate) to the one-dimensional case (beam). The article presents a convenient algebraic form of the solution and provides new case studies to demonstrate the practicality of the proposed formulation. Numerical results are also presented to illustrate the influence of porosity distribution on SCFs for different types of FGPBs. Furthermore, the article validates the numerical consistency of the mechanical property changesin FG beams without porosity and the SCF by comparing them with available results.

• 대한수학회지
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• 제48권2호
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• pp.267-288
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• 2011

In this paper, we construct eight infinite families of ternary linear codes associated with double cosets with respect to certain maximal parabolic subgroup of the special orthogonal group $SO^-$(2n, q). Here q is a power of three. Then we obtain four infinite families of recursive formulas for power moments of Kloosterman sums with square arguments and four infinite families of recursive formulas for even power moments of those in terms of the frequencies of weights in the codes. This is done via Pless power moment identity and by utilizing the explicit expressions of exponential sums over those double cosets related to the evaluations of "Gauss sums" for the orthogonal groups $O^-$(2n, q).

• Journal of Power Electronics
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• 제12권5호
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• pp.830-841
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• 2012

Active power filters (APF) can be employed for harmonic compensation in power systems. In this paper, a fuzzy based method is proposed for identification of probable APF nodes of a radial distribution system. The modified adaptive particle swarm optimization (MAPSO) technique is used for final selection of the APFs size. A combination of Fuzzy-MAPSO method is implemented to determine the optimal allocation and size of APFs. New fuzzy membership functions are formulated where the harmonic current membership is an exponential function of the nodal injecting harmonic current. Harmonic voltage membership has been formulated as a function of the node harmonic voltage. The product operator shows better performance than the AND operator because all harmonics are considered in computing membership function. For evaluating the proposed method, it has been applied to the 5-bus and 18-bus test systems, respectively, which the results appear satisfactorily. The proposed membership functions are new at the APF placement problem so that weighting factors can be changed proportional to objective function.

• Coupled systems mechanics
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• 제4권1호
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• pp.99-114
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• 2015

In this paper, a refined exponential shear deformation beam theory is developed for bending analysis of functionally graded beams. The theory account for parabolic variation of transverse shear strain through the depth of the beam and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. Contrary to the others refined theories elaborated, where the stretching effect is neglected, in the current investigation this so-called "stretching effect" is taken into consideration. The material properties of the functionally graded beam are assumed to vary according to power law distribution of the volume fraction of the constituents. Based on the present shear deformation beam theory, the equations of motion are derived from Hamilton's principle. Analytical solutions for static are obtained. Numerical examples are presented to verify the accuracy of the present theory.