• Journal of the Korean Data and Information Science Society
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• 제18권4호
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• pp.1205-1214
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• 2007

We define a skew-symmetric double Rayleigh distribution by a symmetric double Rayleigh distribution, and derive an approximate maximum likelihood estimator(AML) and a moment estimator(MME) of a skewed parameter in a skew-symmetric double Rayleigh distribution, and hence compare simulated mean squared errors of those two estimators. We also compare simulated mean squared errors of two proposed estimators of reliability in two independent skew-symmetric double Rayleigh distributions.

• Journal of the Korean Data and Information Science Society
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• 제20권6호
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• pp.1199-1206
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• 2009

This paper deals with the estimation based on progressive Type-II censored samples from the double Rayleigh distribution. We derive some estimators of the location and scale parameters of the double Rayleigh distribution based on progressive Type-II censored samples. We compare the proposed estimators in the sense of the mean squared error for various censored samples.

• Communications for Statistical Applications and Methods
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• 제15권3호
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• pp.367-378
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• 2008

In this paper, we derive the approximate maximum likelihood estimators of the scale parameter and the location parameter in a double Rayleigh distribution based on multiply Type-II censored samples. We compare the proposed estimators in the sense of the mean squared error for various censored samples.

• 대한기계학회논문집
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• 제18권12호
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• pp.3297-3304
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• 1994

Experimental investigation have been made to study the double-diffusive nature of convection of an initially stratified salt-water solution heated from below in a cylindrical cavity. The objective is to examine the process of mixed-layer formation, the flow phenomena, the heat transfer characteristics, and temperature and concentration distribution according to the changes in the effective Rayleigh number based on the reference height which represents the relation of temperature and concentration gradient. The types of initially formed flow pattern are categorized in three regimes depending on the effective Rayleigh number ; stagnant flow regime, single mixed-layer flow regime and successively formed multiple mixed-layer flow regime. The temperature and concentration profiles are both uniform in each layer due to convective mixing in the layered flow regime, but both linear in stagnant flow regime and single mixed-layer flow regime. At the interface between adjacent layers, the temperature changes smoothly but the concentration changes rapidly. The layers expand by diffusion of concentration through the interface along with its random fluctuation.

• Structural Engineering and Mechanics
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• 제4권5호
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• pp.541-552
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• 1996

This paper is concerned with the structural optimization problem of maximizing the compressive buckling load of orthotropic rectangular plates for a given volume of material. The optimality condition is first derived via variational calculus. It states that the thickness distribution is proportional to the strain energy density contrary to popular claims of constant strain energy density at the optimum. An engineers physical meaning of the optimality condition would be to make the average strain energy density with respect to the depth a constant. A double cosine thickness varying plate and a double sine thickness varying plate are then fine tuned in a one parameter optimization using the Rayleigh-Ritz method of analysis. Results for simply supported square plates indicate an increase of 89% in capacity for an orthotropic plate having 100% of its fibers in $0^{\circ}$ direction.

• Journal of the Optical Society of Korea
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• 제20권5호
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• pp.541-546
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• 2016

In this paper, by using the Rayleigh-Sommer field theory and the cross-spectral density function, the analytical expression for the intensity distribution of a double half-Gaussian hollow beam in a turbulent atmosphere is obtained. The influence of the initial spot size of this beam on its propagation properties in a turbulent atmosphere is simulated, and the intensity distributions for such beams with different spot sizes are obtained. The results show that the initial spot size has an important influence on the propagation properties in the near field, while this influence in the far field is very weak.

• 대한조선학회지
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• 제26권1호
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• pp.46-62
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• 1989

최근 현대 선박해양연구소 구조연구실에서 4,800대 적재 자동차 전용운반선 2척에 대하여 울산 미국간 각각 왕복 1항차에 걸쳐 실선계측을 수행하였다. 계측의 주요 목적은 자동차 운반선의 부분 횡격벽의 횡강도 검토 및 항해중 파랑하중에 대한 선체 응답의 연구등이다. 계측된 data를 가지고 단기 응답해석(short-term analysis)을 하였는데 항해중 선체에 발생하는 응력의 진폭의 분포는 대체로 Rayleigh 분포를 잘따르고 있다. 그리고 횡격벽에서의 응력은 상갑판의 선측 방향 수평가속도와 밀접한 관계가 있는 것으로 나타났다. 단기 응답해석에서 얻어진 결과를 가지고 선박 운항시 발생 가능한 최대 응답치를 얻기 위하여 장기 응답해석(long-term analysis)을 수행하였다. 해석결과중 본 계측 대상선의 Fr.132 부분 횡격벽의 응력집중 부분에서 10년 동안의 예측 최대응력은 약 $2,150kg/cm^2$이었고 이 부분에 대한 예측 피로수명은 약 200일 이었는데 이 값은 실제 본선이 처녀해항후 crack손상을 입은 기간과 잘 일치하고 있다.