• 해양환경안전학회지
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• 제1권2호
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• pp.107-118
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• 1995

This study is for decision making on distribution of resources so as to improve the effectiveness of initial disaster relief efforts. It is very important that relief efforts should be accomplished appropriately at the initial disaster. Furthermore, efficient allocation of relief resources such as rescuer, shelter, relief goods, relief funds, medical and relief equipments is also the first step to achieve main objective of relief efforts when disaster occurs. For this purpose, this study establishes flood as a imaginery disaster and develops a model for efficient distribution of resources when flood outbreaks. This model fixes initial 72 hours, which is subdivided into three intervals, as a initial disaster range. The model is to set a prioity against alloction of relief resources by each time zone which is related to damaged degree( Red Tag, Yellow Tag, Green Tag). Experts in this field input their experience into this model, and these are analyzed by Analytic Hierachy Process(AHP)/Expert Choice(EC) software. Therefore, we can decide a prioity against distribution of resources by each time zone which is in accordance with damaged degree. The result of this study would be helpful to a person who is in charge of relief from calamity in order him to make a decision toward distribution of resources.

• Journal of Radiation Protection and Research
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• 제43권1호
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• pp.10-19
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• 2018

Background: Monte Carlo (MC) simulation is the most accurate for calculating radiation dose distribution and determining patient dose. In MC simulations of the therapeutic accelerator, the characteristics of the initial electron must be precisely determined in order to achieve accurate simulations. However, It has been computation-, labor-, and time-intensive to predict the beam characteristics through predominantly empirical approach. The aim of this study was to analyze the relationships between electron beam parameters and dose distribution, with the goal of simplifying the MC commissioning process. Materials and Methods: The Varian Clinac 2300 IX machine was modeled with the Geant4 MC-toolkit. The percent depth dose (PDD) and lateral beam profiles were assessed according to initial electron beam parameters of mean energy, radial intensity distribution, and energy distribution. Results and Discussion: The PDD values increased on average by 4.36% when the mean energy increased from 5.6 MeV to 6.4 MeV. The PDD was also increased by 2.77% when the energy spread increased from 0 MeV to 1.019 MeV. In the lateral dose profile, increasing the beam radial width from 0 mm to 4 mm at the full width at half maximum resulted in a dose decrease of 8.42% on the average. The profile also decreased by 4.81% when the mean energy was increased from 5.6 MeV to 6.4 MeV. Of all tested parameters, electron mean energy had the greatest influence on dose distribution. The PDD and profile were calculated using parameters optimized and compared with the golden beam data. The maximum dose difference was assessed as less than 2%. Conclusion: The relationship between the initial electron and treatment beam quality investigated in this study can be used in Monte Carlo commissioning of medical linear accelerator model.

• 대한기계학회논문집
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• 제14권1호
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• pp.138-144
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• 1990

본 연구에서는 피로크랙 진전수명에 대하여 대단히 중요한 초기 크랙 길이 분 포 및 타 파라마터의 크랙 진전수명에 미치는 영향을 폭넓게 논함과 동시에 또 이러한 영향을 손쉽게 예측할 수 있는 실용적 근사식을 제시하는 것이다.

• 한국해양공학회지
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• 제17권5호
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• pp.48-56
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• 2003

This paper has developed an efficient nonlinear finite element method that covers both initial deformations and initial stresses of general distribution in calculating the ultimate strength of ring-stiffened cylinders. The developed method and two widely-used commercial codes (NASTRAN and ABAQUS) were simultaneously applied to the same analysis model within the extent of those commercial codes' coverage to check the validity of the present method. After the validity check, it was used for parametric studies for more general cases of initial stress distribution, which produced some useful information about the imperfection sensitivity of the ultimate strength of ring-stiffened cylinders.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제6권1호
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• pp.51-59
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• 2003

This paper has developed an efficient nonlinear finite element method that covers both initial deformations and initial stresses of general distribution in calculating the ultimate strength of ring-stiffened cylinders. The developed method and two widely-used commercial codes (NASTRAN and ABAQUS) were simultaneously applied to the same analysis model within the extent of those commercial codes' coverage to check the validity of the present method. After the validity check, it was used for parametric studies for more general cases of initial stress distribution, which produced some useful information about the imperfection sensitivity of the ultimate strength of ring-stiffened cylinders.

• 전기학회논문지
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• 제56권3호
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• pp.451-456
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• 2007

This paper presents a problem that reconfigure distribution power system using branch exchange method. Optimal reconfiguration problem calculates line loss, voltage condition about system states of all situations that become different according to line On/off status, and search for optimum composition of these. However, result is difficult to be calculated fast. Because radiated operation condition of system is satisfied using many connection and sectionalize switches in the distribution power system. Therefore, in this paper, optimization method for reducing system total loss and satisfying operating condition of radial and constraints condition of voltage is proposed using the fastest branch exchange. And optimal solution at branch exchange algorithm can be wrong estimated to local optimal solution according to initial operating state. Considering this particular, an initial operating point algorithm is added and this paper showed that optimal solution arrives at global optimal solution.

• 조명전기설비학회논문지
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• 제25권5호
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• pp.15-21
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• 2011

This paper presents an analyzing method of the capacitance of the power transformer for initial voltage distribution and insulation design. When a high incoming surge voltage is accidently occurred in windings of transformer, it does not distribute equally in the windings. This phenomenon makes electric field concentration and the insulating material could be break. Initial voltage distribute mostly depends on capacitances between winding to winding or winding to core in the transformer. If the C network can be structuralized into the equivalent circuit model and be calculated each capacitance element value by circuit analysis and FEM(Finite Element Method) simulation program, the transformer designer could know the place where the structure is to be modified or the insulation to be reinforced. This method quickly provides the data of the voltage distribution in each winding to the designer.

• 한국안전학회지
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• 제8권2호
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• pp.64-71
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• 1993

In this study, the purpose is to investigate the influence of initial residual stresses on the fatigue crack growth behaviors after the distribution of initial residual stresses Is measured when the crack is growing from the compressive residual stresses field to the tensile residual stress field. Also, the Influence of the variation of residual stress distribution on the fatigue crack growth behaviors at the crack tip is studied when the initial crack li applied on base metal, weld metal and HAZ respectively.

• 응용통계연구
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• 제18권1호
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• pp.137-146
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• 2005

신경망은 전통적인 시계열 기법들에 비해 대체적으로 예측성능의 우수함이 입증되었으나 계절성과 추세성을 갖는 시계열자료에 대해 예측력이 떨어지는 단점을 가지고 있다. 최근에는 Ensemble 기법인 Bagging Algorithm과 신경망의 혼합모형인 Bagging Neural Network이 개밭되었다. 이 기법은 분산과 편향을 많이 줄여줌으로써 더 좋은 예측을 할 수 있는 것으로 나타났다. 그러나 Ensemble 기법을 이용한 예측모형은 시계열자료를 적합 시키는데 있어 초기부여확률 및 예측자 선정시의 문제점을 가지고 있다. 이에 본 연구에서는 이러한 문제점을 해결하고 더불어 예측력을 향상시키기 위한 방법으로 초기부여확률이 균일분포가 아닌 순차적인 형태의 분포를 제시하고 신경망을 예측자로 활용한 변형된 Ensemble Algorithm을 제안한다. 또한 예측모형의 평가를 위해 실제자료를 가지고 기존 예측모형들과 제안한 방법을 이용하여 예측하고 각 MSE의 비교를 통하여 예측정확도를 알아보고자 한다.

• 한국자동차공학회논문집
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• 제5권4호
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• pp.207-218
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• 1997

A new blank design method is introduced to predict the blank shape and the strain distribution in the sheet metal forming process. This method deals with only one step from the final shape to the initial blank using the ideal forming theory. Based on this theory, a three-dimensional membrane finite element code has been developed to design an initial blank in the sheet metal forming process. In this paper, the designs of initial blanks for forming a cylindrical cup, a rectangular cup, and a front fender are presented as examples. Also, it compares the two shapes, the target shape with the shape which is deformed from the initial blank using the FEM analysis code. The results illustrate the information that this direct design code is useful in the preliminary design state.