• The Journal of Natural Sciences
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• v.5 no.1
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• pp.29-36
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• 1992

The experiment was conducted to evaluate the effects of organic fertilizer. Sarang of fermented poultry manure. Miwon glutamic acid fertilizer and poultry manure, on the growth and yield of radish cultivated in spring and autumn. 1) The growth of leaf length, leaf weight, root length, root diameter and root weight of radish in two culture types was stimulated in order of NPK, fermented poultry manure + 1/5NK, fermented poultry manure, poultry manure and control treatment, and chlorophyll and nitrogen content of leaf were increased in order of the above mentioned fertilizers.2) Yield decreased in fermented poultry manure plot of 450kg application comparison with NPK plot but the one of 1800kg fermented poultry manure was increased. The yield of 450kg Sarang plot was sufficient as compared with Korean average yield of spring and autumn culture.3) The difference of growth of radish between treatments of fermented poultry manure and NPK was lowered by continuous application of Sarang organic fertilizer.4) Soil nitrogen content and exchangeable Mg were similar in all treatments but soil pH, the contents of organic matter, $P_2 O_5$ and Ca were high in the fermented poultry manure treatment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.2019-2031
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• 2004

The least-squares formulation for rigid-plasticity based on J$_2$-flow rule and infinitesimal theory and its meshfree implementation using moving least-squares approximation are proposed. In the least-squares formulation the squared residuals of the constitutive and equilibrium equations are minimized. Those residuals are represented in a form of first-order differential system using the velocity and stress components as independent variables. For the enforcement of the boundary and frictional contact conditions, penalty scheme is employed. Also the reshaping of nodal supports is introduced to avoid the difficulties due to the severe local deformation near the contact interface. The proposed least-squares meshfree method does not require any structure of extrinsic cells during the whole process of analysis. Through some numerical examples of metal forming processes, the validity and effectiveness of the method are investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2312-2321
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• 2002

The first-order least-squares meshfree method for linear elasticity is presented. The conventional and the compatibility-imposed least-squares formulations are studied on the convergence behavior of the solution and the robustness to integration error. Since the least-squares formulation is a type of mixed formulation and induces positive-definite system matrix, by using shape functions of same order for both primal and dual variables, higher rate of convergence is obtained for dual variables than Galerkin formulation. Numerical examples also show that the presented formulations do not exhibit any volumetric locking for the incompressible materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1849-1858
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• 2002

An h-adaptive scheme of first-order least-squares meshfree method is presented. A posteriori error estimates, which can be readily computed from the residual, are also presented. For elliptic problem the error indicators are further improved by applying the Aubin-Nitsche method. In the proposed refinement scheme, Voronoi cells are utilized to insert nodes at appropriate positions. Through numerical examples, it is demonstrated that the error indicators reveal good correlations with the actual errors and the adaptive first-order least-squares meshfree method is effectively applied to the localized problems such as the shock formation in fluid dynamics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1605-1612
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• 2001

Least-squares meshfree method is presented. Conventional meshfree methods based on the Galerkin formulation suffer from inaccurate numerical integration. Least-squares formulation exhibits rather different integration-related characteristics. It is demonstrated through numerical examples that least-squares formulation is much more robust to integration errors than the Galerkin's. Therefore efficient meshfree methods can be devised by combining very simple integration algorithms and least-squares formulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.732-735
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• 1995

A meshless method which is the new computational method being developed recently, is applied to the simulation of large deformation problems. Among the many types of meshless methods, the Reproducing Kernel particle method (RKPM) is used and the nearly incompressible hyperelastic materials are employed in simulations. The meshless methods can avoid metsh distortions and mesh entanglements that may frequently happen when the mesh-based methods like finite element method are used for the simulations of largely deformed materials. A general features of meshless methods are reviewed and the formulation of RKPM is presented. Next, the performance of explicit RKPM is demonstrated by examples.

• Computational Structural Engineering
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• v.11 no.1
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• pp.261-274
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• 1998

In this paper, local and global error estimates for the element-free Galerkin (EFG) method are proposed. The essence of proposed error estimates is to use the difference between the values of the projected stress and these given directly by the EFG solution. The stress projection can be obtained simply by taking product of shape function based on a different domain of influence with the stresses at nodes. In this study, it was found that the effectivity index is optimized if the domain of influence in stress projection procedure is the smallest that retains regularity of the matrices in EFG. Numerical tests are shown for various 1D and 2D examples illustrating the good effectiveness of the proposed error estimator in the global energy norm and in the local error estimates.

• Korean Security Journal
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• no.60
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• pp.197-226
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• 2019

The objective of this study is to examine the effects of servant leadership of security martial arts instructors on the exercise commitment and training satisfaction of trainees. To achieve the objective of this study, the data was collected from 300 trainees of security martial arts gyms located in Seoul, Incheon, and Gyeonggi-do regions by using the convenience sampling method. Total 281 questionnaires were used for the analysis after excluding 19 questionnaires. Using the SPSS 23.0 for data-process, this study conducted the frequency analysis, exploratory factor analysis, reliability analysis, correlation analysis, and multiple regression analysis. First, all the variables showed positive(+) correlations. Second, the presentation of vision of instructors' servant leadership had positive(+) effects on the behavioral commitment while the devoted attitude of instructors' servant leadership had positive(+) effects on the cognitive commitment. Third, the presentation of vision, formation of community, and support for growth of instructors' servant leadership had positive(+) effects on the psychological elements while the presentation of vision and support for growth had positive(+) effects on the environmental elements. The presentation of vision and formation of community had positive(+) effects on the physical elements while the presentation of vision and formation of community had positive(+) effects on the educational elements. The presentation of vision, formation of community, and support for growth had positive(+) effects on the social elements. Fourth, both cognitive commitment and behavioral commitment out of trainees' exercise commitment had positive(+) effects on the psychological elements, environmental elements, physical elements, and educational elements of training satisfaction while only the cognitive commitment had positive(+) effects on the social elements. In summary, the security martial arts instructors should show the leadership like presentation of vision and devotion, and also try hard to satisfy the expectation in many areas to raise the exercise commitment.

• Korean Journal of Weed Science
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• v.3 no.1
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• pp.50-56
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• 1983

A study was conducted to evaluate the weed population as affected by repeated application of fertilizers for 15 years (nonfertilized, PK, NK, NPK, NPK+Compost, NPK+Straw and NPK+lime). Alopecurus aequalis authority did not grow at all without P application and lime reduced the population of A. aequalis. Total number of weeds were the largest at 5-10cm soil layer and increased by application of compost and straw. Monochoria vaginalis dominated in NPK+compost and NP plot. Scirpus hotarui dominated in NPK+straw. Both Eleocharis kuroguwai and Potamogeton distinctus dominated in nonfertilized plot. Numbers of M. vaginalis and S. hotarui were larger low pH 6 while that of E. kuroguwai and P. distinctus at pH 6 to pH 7. Incidence of M. vaginalis and S. hotorui was great at pH's lower than 6, while E. kuroguwai and P. distinctus favored pH's ranging from 6 to 7.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.101-105
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• 2001

본 연구는 유연 생산 시스템에서 버퍼 할당 최적화 알고리즘을 제시한다. 기존의 연구들과는 달리 제안된 알고리즘은 시스템의 복잡성과 Combinatorial특성을 모두 다를 수 있다. 알고리즘은 시뮬레이션을 사용하여 시스템의 복잡성을 모델링하고 수정된 유전 알고리즘을 사용하여 Combinatorial특성을 다루며 버퍼를 최적으로 시스템에 할당하게 한다. 제안된 알고리즘은 첫 번째 제한된 버퍼가 있는 상황에서 시스템 Output을 최대화하는 목적함수를 사용하여 최적 버퍼할당을 찾아내는 것과, 두 번째 원하는 Output을 달성할 수 있는 최소의 총 버퍼 수와 할당을 찾아내는 두 가지 목적함수에 적용된다. 마지막으로 유연 생산 시스템의 성능을 결정짓는 다른 요소들과의 관계를 살펴보기 위해 무인 운반 시스템의 발주방식과 무인 운반차의 수 등을 변화시켜 실험을 수행하고 그 결과를 분석한다.