• Communications of the Korean Mathematical Society
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• v.18 no.4
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• pp.587-602
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• 2003

본 논문에서는 벡터값을 가지는 함수로 이루어진 벡터 변분 부등식들의 해집합사이의 관계, 미분 불가능한 볼록함수로 이루어진 벡터 볼록 최적화 문제의 해집합들과 볼록함수의 아래미분으로 표현된 벡터 변분부등식의 해집합들과의 관계, 제약집합이 볼록 함수로 구체적으로 주어질 때의 벡터 변분부등식의 해가 될 필요 충분조건, 섭동된 강 단조 벡터 변분부등식의 안정성 결과와 섭동된 벡터 강 볼록 최적화문제에의 적용에 대한 최근 연구 결과를 정리한다.

• The Korean Journal of Applied Statistics
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• v.30 no.5
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• pp.665-679
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• 2017

When measuring productive efficiency, often it is necessary to have knowledge of the production frontier function that shows the maximum possible output of production units as a function of inputs. Canonical parametric forms of the frontier function were initially considered under the framework of stochastic frontier model; however, several additional nonparametric methods have been developed over the last decade. Efforts have been recently made to impose shape constraints such as monotonicity and concavity on the non-parametric estimation of the frontier function; however, most existing methods along that direction suffer from unnecessary non-smooth points of the frontier function. In this paper, we propose methods to estimate the smooth frontier function with monotonicity for stochastic frontier models and investigate the effect of imposing a monotonicity constraint into the estimation of the frontier function and the finite dimensional parameters of the model. Simulation studies suggest that imposing the constraint provide better performance to estimate the frontier function, especially when the sample size is small or moderate. However, no apparent gain was observed concerning the estimation of the parameters of the error distribution regardless of sample size.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.4
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• pp.37-48
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• 1984

The yield-line analysis is used for earring out the limit analysis of reinforced concrete slabs which are for example like those of vertical walls of tanks subjected to the loads of hydrostatical type. It is considered both isotropic and orthotropic reinforcement using the coefficient of orthotropy with different edge conditions. The yield-line analysis is carried out by using the vertical work method and four collapse mechanisms including the fan mechanisms which is more realistic than over diagonal mechanisms is considered. It is found that the fan mechanisms are more complicated than ever simple diagonal mechanisms which have used for the orthotropically reinforced concrete slabs subjected to hydrostatic pressures. Especially Horton's study is extended in this study, and they are formulated to the constrained multi-variables nonlinear optimization problems, which are solved by the Rosen-Brock Hillclimb Procedure Program and are more critical.