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Cho Sungwon,이종무,우종훈 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1
Production planning is a key part of production management of manufacturing enterprises. Since computerization began, modern production planning has been developed starting with Material Requirement Planning (MRP), and today Enterprise Resource Planning (ERP), Advanced Planning and Scheduling (APS), Supply Chain Management (SCM) has been spreading and advanced. However, in the shipbuilding field, rather than applying these general-purpose production planning methodologies, in most cases, each shipyard has developed its own production planning system. This is because the applications of general-purpose production planning methods are limited due to the order-taking industry such as shipbuilding with highly complicated construction process consisting of millions of parts per ship. This study introduces the design and development of the production planning system reflecting the production environment of heavy shipyards in Korea. Since Korean shipyards such as Hyundai, Daewoo and Samsung build more than 10 ships per year (50e70 ships in the case of large shipyards), a planning system for the mixed production with complex construction processes is required. This study draws requirements using PI/BPR (process innovation and business process reengineering) methodology to develop a production planning system for shipyards that simultaneously build several ships. Then, CBD software development methodology was applied for the design and implementation of planning system with drawn requirements. It is expected that the systematic development procedure as well as the requirements and functional elements for the development of the shipyard production planning system introduced in this study will be able to present important guidelines in the related research field of shipbuilding management.
A MAXIMUM PRINCIPLE FOR NON-NEGATIVE ZEROTH ORDER COEFFICIENT IN SOME UNBOUNDED DOMAINS
Cho, Sungwon The Kangwon-Kyungki Mathematical Society 2018 한국수학논문집 Vol.26 No.4
We study a maximum principle for a uniformly elliptic second order differential operator in nondivergence form. We allow a bounded positive zeroth order coefficient in a certain type of unbounded domains. The results extend a result by J. Busca in a sense of domains, and we present a simple proof based on local maximum principle by Gilbarg and Trudinger with iterations.
A CERTAIN EXAMPLE FOR A DE GIORGI CONJECTURE
Cho, Sungwon Chungcheong Mathematical Society 2014 충청수학회지 Vol.27 No.4
In this paper, we illustrate a counter example for the converse of a certain conjecture proposed by De Giorgi. De Giorgi suggested a series of conjectures, in which a certain integral condition for singularity or degeneracy of an elliptic operator is satisfied, the solutions are continuous. We construct some singular elliptic operators and solutions such that the integral condition does not hold, but the solutions are continuous.
The Effect of Population Aging on Stock Prices in Korea
Sungwon Cho 한국자료분석학회 2020 Journal of the Korean Data Analysis Society Vol.22 No.4
This empirical study examines the relationship between population aging and stock prices using the Korean time-series data. The time-series properties of the variables are examined via the unit root and the cointegration test, and error correction model is estimated to investigate the effect of population aging on stock prices in Korea. The proportion of the elderly, aged over 65, to the working age population is used as a measure of population aging. The quarterly data sample covers the period from 1991 to 2020. The unit root test shows that the variables are difference-stationary, and the following cointegration test results indicate a long-run equilibrium relationship exists between population aging and stock prices. Based on the cointegration test result, an error correction model is constructed and estimated. The estimation result of the error correction model shows that the effect of population aging on stock price is statistically insignificant. Empirical results of this paper suggests that population aging would not have significant effect on stock prices in Korea, and the trend of population aging would not adversely affect the Korean stock market.
ON SOME PROPERTIES OF BARRIERS AT INFINITY FOR SECOND ORDER UNIFORMLY ELLIPTIC OPERATORS
Sungwon Cho 한국수학교육학회 2018 純粹 및 應用數學 Vol.25 No.2
We consider the boundary value problem with a Dirichlet condition for a second order linear uniformly elliptic operator in a non-divergence form. We study some properties of a barrier at innity which was introduced by Meyers and Serrin to investigate a solution in an exterior domains. Also, we construct a modied barrier for more general domain than an exterior domain.
A Priori Boundary Estimations for an Elliptic Operator
Cho, Sungwon The Basic Science Institute Chosun University 2014 조선자연과학논문집 Vol.7 No.4
In this article, we consider a singular and a degenerate elliptic operators in a divergence form. The singularities exist on a part of boundary, and comparable to the logarithmic distance function or its inverse. If we assume that the operator can be treated in a pointwise sense than distribution sense, with this operator we obtain a priori Harnack continuity near the boundary. In the proof we transform the singular elliptic operator to uniformly bounded elliptic operator with unbounded first order terms. We study this type of estimations considering a De Giorgi conjecture. In his conjecture, he proposed a certain ellipticity condition to guarantee a continuity of a solution.
Cointegration Relationship between Income Inequality and Economic Growth: The Korean Case
( Sungwon Cho ) 서강대학교 지암남덕우경제연구원(구 서강대학교 시장경제연구소) 2018 시장경제연구 Vol.47 No.2
This study empirically investigates the existence of a cointegration relationship between income inequality and economic growth using Korean time-series data. The income quintile ratio is adopted as the variable representing income inequality. This variable is defined as the ratio between the average income of the top 20% and the bottom 20% income brackets, based on household income data obtained from Statistics Korea. The cointegration test result shows that there is a long-run equilibrium relationship between income inequality and economic growth, and that income inequality is positively correlated with economic growth over the period 1990-2017.
A CERTAIN EXAMPLE FOR A DE GIORGI CONJECTURE
Sungwon Cho 충청수학회 2014 충청수학회지 Vol.27 No.4
In this paper, we illustrate a counter example for the converse of a certain conjecture proposed by De Giorgi. De Giorgi suggested a series of conjectures, in which a certain integral condi-tion for singularity or degeneracy of an elliptic operator is satised, the solutions are continuous. We construct some singular elliptic operators and solutions such that the integral condition does not hold, but the solutions are continuous.