• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.1-8
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• 2018

A fuel cell is an energy conversion device that converts a chemical energy directly into an electrical energy and has higher energy efficiency than an internal combustion engine, but solid oxide fuel cell (SOFC) consisting of brittle ceramic material remains as a major issue regarding the mechanical properties as the crack formation and propagation. In this study, the stress distribution and crack behavior around the crack tip were evaluated, due to investigated the effects of the surface crack at the operating condition of high temperature. As a result, the difference of the generated stress was insignificant at operating conditions of high temperature according to the surface crack length changes. This is because, the high stiffness interconnect has a closed structure to suppress cell deformation about thermal expansion. The stress intensity factor ratio $K_{II}/K_I$ increased as the crack depth increased, at that time the effect of $K_{II}$ is larger than that of $K_I$. Also the maximum stress intensity factor increased as the crack depth increased, but the location of crack was generated at the electrolyte/anode interface, not at the crack tip.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.235-236
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• 2008

Recently, the power load is growing larger and because of the environmental limitation of generation, the expansion of generation facilities are becoming more difficult. For that reason the importance of the demand-side resources come to be higher. One method of the demand-side resource, the DLC Program, has executed, and moreover, the loads which are available to be controlled are increasing. It should be considered of some kinds of power system components such as DLCs, because the fact that using the demand resources will be an important part of the power system. This paper considers the power factor of the load-bus which is shedded in the direct load control program. and then analyze the power system using flow sensitivity and voltage sensitivity. In this paper, we assumed two scenarios through the rank of the load power factor at each bus and to compare and evaluate each case, we used Power World for the simulation.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1126-1139
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• 2016

In this research, for the first time, a new optimization method, i.e., strength Pareto evolutionary algorithm II (SPEA-II), is developed for the burnable poison placement (BPP) optimization of a nuclear reactor core. In the BPP problem, an optimized placement map of fuel assemblies with burnable poison is searched for a given core loading pattern according to defined objectives. In this work, SPEA-II coupled with a nodal expansion code is used for solving the BPP problem of Kraftwerk Union AG (KWU) pressurized water reactor. Our optimization goal for the BPP is to achieve a greater multiplication factor ($K_{eff}$) for gaining possible longer operation cycles along with more flattening of fuel assembly relative power distribution, considering a safety constraint on the radial power peaking factor. For appraising the proposed methodology, the basic approach, i.e., SPEA, is also developed in order to compare obtained results. In general, results reveal the acceptance performance and high strength of SPEA, particularly its new version, i.e., SPEA-II, in achieving a semioptimized loading pattern for the BPP optimization of KWU pressurized water reactor.

• Journal of the Korea Safety Management & Science
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• v.21 no.4
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• pp.31-37
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• 2019

When the foundation work of the underground part of the building structure or the excavation work of the civil engineering structure is carried out, there is the earthwork work by the inevitable process. As the economic situation continues to develop, construction in urban areas is becoming bigger and higher in scale due to the expansion of infrastructure and the rescue of urban dwellings in urban areas, and excavation of underground roads is inevitable. Excavation of the underground part may cause problems in the process difficulty and safety of the earthworks due to the complexity and various characteristics of the ground selected without consideration of the ground characteristics and site conditions. In order to complete the required facilities, it is necessary to secure the design and construction of the retaining walls. In order to complete the required construction, It is an important factor satisfying construction period and economical efficiency.

• Iberoamérica
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• v.12 no.1
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• pp.241-265
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• 2010

The main purpose of this study is to reveal the historical origins of Latin American economic underdevelopment, by answering two research questions; 1)'Why is Latin America underdeveloped?' and 2)'How has colonial experience impacted on the economic growth in Latin America?' First, this essay analyzes long-term tendency of growth domestic product(GDP) per capita data. The data verify that current underdevelopment of Latin American economy is the result of economic stagnation during the eighteenth and nineteenth centuries, when Latin America suffered political and economic instability before and after the independence from Spain and Portugal. It elucidates that colonial experience affected on the economic growth in Latin America. Second, this essay reviews key independent variables of the relationship between colonial experience and economic growth in Latin America. To do so, the study categorizes extant literature into two groups according to the type of its independent variables: 1)internal factor and 2)external factor. Finally, the essay surveys the role of institutions in Latin American economic growth and development. The survey confirms that the importance of institutions in the study of Latin American economic history. In addition, the essay suggests some tasks for further research in Latin American economic history; 1)the construction of basic economic data, 2)the substantialization of the role and characteristics of institutions, and 3)the expansion of research on institutions which overcomes ideological rigidity of existing institutional approach.

• Geomechanics and Engineering
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• v.36 no.6
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• pp.631-640
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• 2024

In the traditional slope stability analysis, ignoring the spatial variability of slope soil will lead to inaccurate analysis. In this paper, the K-L series expansion method is adopted to simulate random field of soil strength parameters. Based on Random Limit Equilibrium Method (RLEM), the influence of variation coefficient and fluctuation range on reliability of soil slope supported by micro-pile is investigated. The results show that the fluctuation ranges and the variation coefficients significantly influence the failure probability of soil slope supported by micro-pile. With the increase of fluctuation range of soil strength parameters, the mean safety factor of the slope increases slightly. The failure probability of the soil slope increases with the increase of fluctuation range when the mean safety factor of the slope is greater than 1. The failure probability of the slope increases by nearly 8.5% when the fluctuation range is increased from δ_v=2 m to δ_v =8 m. With the increase of the variation coefficient of soil strength parameters, the mean safety factor of the slope decreases slightly, and the probability of failure of soil slope increases accordingly. The failure probability of the slope increases by nearly 31% when the variation coefficient increases from COV_c=0.2, COV_φ=0.05 to COV_c=0.5, COV_φ=0.2.

• The Korean Journal of Health Service Management
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• v.9 no.3
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• pp.115-126
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• 2015

Objectives : This research was performed to investigate the characteristics and determination factors of health care policy satisfaction and welfare recognition for health insurance & health care financing. Methods : The utilized data were 4,174 cases who responded to a welfare recognition survey in the 8th wave of the Korea Welfare Panel Study (2013). The statistical methodology used in this study is the multiple regression model. Results : The significant affecting factors of health care policy satisfaction were age, education, household income, welfare attitudes, and health status. Medical utilization & private medical insurance were not related to health care policy satisfaction. The affecting factors of health insurance reinforcement were age, health status, welfare attitudes. The affecting factors of health care financing expansion were age, economic activity type, medical utilization, welfare attitudes. The affecting factors of welfare attitudes were age, economic activity type, household income, health insurance, and health status. Conclusions : Health care policy satisfaction, health insurance reinforcement, and health care financing expansion were all affected by age and welfare attitude; but this was not the case for private health insurance. This study recommended that the Korean government provide active planning for reinforcement of health insurance and publicity of the health care system in order to accord with the prospects of people.

• Journal of Power System Engineering
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• v.13 no.4
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• pp.11-17
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• 2009

This paper deals with the effects of pulsating flow on volumetric efficiency, which may be generated during the gas exchange procedure, due to piston motion, valve event on intake and exhaust stroke and unsteady flow of turbocharger of a three-cylinder four stroke turbo-charged diesel engine. Consequently, volumetric efficiency affects significantly the engine performance; torque characteristics, fuel economy and further to emission and noise level. As the expansion ratio became larger the engine speed varies and torque increases, the pressure pulsation in an exhaust gas pipe acts as an increasing factor of intake air charging capacity totally. The phase and amplitude of pressure pulsation in the intake system only affects volumetric efficiency favorably, if it is well matched and tuned effectively to the engine. Thus, to verify the exact phase and amplitude of the pressure variation is the ultimate solution for the air-flow ratio assessment in the intake stroke. Some experimental results of pressure diagrams in the intake pipe and gas-flow of turbine in-outlet are presented, under various kinds of operating condition.

• Health Policy and Management
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• v.20 no.1
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• pp.1-18
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• 2010

This article examines social determinants of population health in OECD countries, where life years, infant mortality, and PYLL are used as proxy variables of health. The unit of analysis is a country which is the OECD affiliate. A panel regression estimation is chosen as a method, using OECD Health Data. The results are: the increasing national health expenditure affected positively to improve population health. Education was rather a significant determinant of health than income level. The government direct investment for public health did not contribute positively to enhance population health. The expansion of health care coverage was working positively for improving health, but with a time lag. The supply of doctors was a most influential determinant of health. In case of Korea, the coverage expansion of health care was the most important determinant of health. The supply of doctors was, however, not a positive factor for better health, which is different result with the case of OECD countries.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.2
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• pp.21-31
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• 2015

The world air transport industry has grown steadily with quantitative expansion. The volume of air transport in the world is skyrocketing with the open-sky trend. Air passengers from or to South Korea has shown 5% of annual growth for the last couple of decades which caused South Korea now ranking in 18th in the World for air transport market size. Quantitative expansion of Air transport affects in policy making of air transport operators, such as airports, airlines or authorities, directly and indirectly. Especially, Aviation Safety field should be supported by policy regime with the growth of air transport volume, assured resources for continuous monitoring is standing out as a vital factor. This study is to estimate social costs caused by aviation accidents and investment costs for aviation safety by airports, airlines and authorities as operators. Estimated investment costs for aviation safety verified by comparing and analysing them. Precedent studies were reviewed to refer research methodology to calculate aviation accident costs and safety costs of operators. Safety costs of operators was calculated with literature researches and interview surveys among professionals of each operators in rational range.