• Communications for Statistical Applications and Methods
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• v.24 no.3
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• pp.241-254
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• 2017

Drawing a sample can be costly or time consuming in some studies. However, it may be possible to rank the sampling units according to some baseline auxiliary covariates, which are easily obtainable, and/or cost efficient. Ranked set sampling (RSS) is a method to achieve this goal. In this paper, we propose a modified approach of the RSS method to allocate units into an experimental study that compares L groups. Computer simulation estimates the empirical nominal values and the empirical power values for the test procedure of comparing L different groups using modified RSS based on the regression approach in analysis of covariance (ANCOVA) models. A comparison to simple random sampling (SRS) is made to demonstrate efficiency. The results indicate that the required sample sizes for a given precision are smaller under RSS than under SRS. The modified RSS protocol was applied to an experimental study. The experimental study was designed to obtain a better understanding of the pathways by which positive experiences (i.e., goal completion) contribute to higher levels of happiness, well-being, and life satisfaction. The use of the RSS method resulted in a cost reduction associated with smaller sample size without losing the precision of the analysis.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.2
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• pp.93-103
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• 2014

This paper establishes the empirical model based on Hall's(1990) and Basu' s(1996) models, estimates the five types of productivity in the medical service industry over the period 1975:1-2010:4, and analyzes the cyclicality of measured productivities and their correlations with the industrial real wage. The empirical results are summarized as the followings. First, there proved to be substantial market power in pricing and returns to scale in production for the medical service industry. Second, the three types of productivity among 5 types showed to be procyclical. Third, the average labor productivity, the original Solow residual, and the cost-based Solow residual are expected to provide reasonable indexes in analyzing the relationship between productivity and real wage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1569-1573
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• 2008

This paper describes a development of Ultrasonic NDE software to analyze steam generator of nuclear power plant. The developed software includes classical analysis method such as A, B, C and D-scan images. And it can analyze the detected internal cracks using 3D image processing method. To do such, we obtain raw data from specimens of real pipeline of power plants, and get the envelope signal using Empirical Mode Decomposition from obtained ultrasonic 1-dimensional data. The reconstructed 3D crack images offer useful information about the location, shape and size of cracks, even if there is no special 2D image analysis technique. The developed analysis software is applied to specimens containing various cracks with known dimensions. The results of application showed that the developed software provided accurate and enhanced 2D images and reconstructed 3D image of cracks.

• The Journal of the Korea Contents Association
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• v.20 no.12
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• pp.13-22
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• 2020

This study aims to find out success factors of crowdfunding on movie projects. For empirical analysis, we collected 583 data of the movie projects from the crowdfunding platform 'Tumblbug'. To figure out the success factors, we examined effects of 10 independent variables on 1 dependent variable. The independent variable includes target amount, project information, reward options, creator funding power, editor recommendation, creator contents power, movie type, number of comments, number of replies, and number of SNS information. The final achievement rate of crowdfunding was set as dependent variable. This study found that the target amount, number of text information, number of video information, editor recommendation, number of backers' reply, and number of SNS information had a significant impact on the achievement rate of the movie crowdfunding project. This study has implications in that it has discovered a variable of editor recommendation and the number of SNS information, and both of them have a positive effect on crowdfunding achievement.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.5
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• pp.201-211
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• 2022

The economic development of most countries in the world has negatively impacted fossil energy resources. Fossil energy sources such as petroleum and coal are increasingly depleted. When energy sources are exhausted, renewable energy sources are growing strongly. Renewable energy development can help to replace diminishing fossil fuels. Furthermore, the usage of renewable energy can contribute to a green economy and sustainable development by protecting the environment. Solar power on the roof is one of the many renewable energy sources available. But at present, the investment in roof voltage systems has not developed strongly in Vietnam. This paper uses the SEM model to evaluate the factors affecting investment in rooftop solar power in some provinces of Vietnam. The article uses the household interview method. The article has given 8 factors affecting the decision to invest in rooftop solar power for households. Research results show that most of the factor variables have a positive impact on the decision to invest in rooftop solar power. Based on assessing the factors affecting the decision to invest in rooftop solar power, the article will provide conclusions and policy suggestions to increase investment in rooftop solar power in Vietnam.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1234-1243
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• 2024

The pressing need to mitigate greenhouse gas emissions has stimulated a renewed interest in nuclear energy worldwide. However, while numerous countries have shown interest in nuclear power over the course of history, many of them have not continued their pursuit and chosen to defer or abandon their peaceful nuclear power projects. Scrapping a national nuclear power program after making initial efforts implies significant challenges in such a course or a waste of national resources. Therefore, this study aims to identify the crucial factors that influence a country's decision to terminate or hold off its peaceful nuclear power programs. Our empirical analyses demonstrate that major nuclear accidents and leadership changes are significant factors that lead countries to terminate or defer their nuclear power programs. Additionally, we highlight that domestic politics (democracy), lack of military alliance with major nuclear suppliers, low electricity demand, and national energy security environments (energy import, crude oil price) can hamper a country's possibility of regaining interest in a nuclear power program after it has been scrapped, suspended, or deferred. The findings of this study have significant implications for policymakers and stakeholders in the energy sector as they strive to balance the competing demands of energy security, and environmental sustainability.

• International Journal of Automotive Technology
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• v.2 no.4
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• pp.157-164
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• 2001

The vehicle electric power system, which consists of two major components: a generator and a battery, which have to provide numerous electrical and electronic systems with enough electrical energy. A detailed understanding of the characteristics of the electric power system, electrical load demands, and the driving environment such as road, season, and vehicle weight is required when the capacities of the generator and the battery are to be determined for a vehicle. An easy-to-use and inexpensive simulation program may be needed to avoid the over/under design problem of the electric power system. A vehicle electric power simulator is developed in this study. The simulator can be utilized to determine the optimal capacities of generators and batteries. To improve the expandability and easy usage of the simulation program, the program is organized in modular structures, and is run on a PC. Empirical electrical models of various generators and batteries, and the structure of the simulation program are presented. For executing the vehicle electric power simulator, data of engine speed profile and electric loads of a vehicle are required, and these data are obtained from real driving conditions. In order to improve the accuracy of the simulator, numerous driving data of a vehicle are logged and analyzed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.8
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• pp.779-791
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• 1990

This paper presents a knowledge based system to solve reactive power/voltage control problem in a power system. A need is recognized for new methods to alleviate a bus voltage limit violation more quickly when a power system becomes an emergency state due to contingency. To cope with this object, a set of indices concept which is used to make bus order list of reactive power injection priority is introduced. A set of indices, based on the overall system conditions, consists of steady state stability index, reactive power transmittance indes, voltage severity index and generator fuel cost index. This scheme and empirical rules of the knowledge on the basis of the human expert result in fast decision-making of the reactive power compensation devices since only the amount of devices is determined by the inference in the knowledge based system when the voltage violation is detected. In this approach, control devices such as shunt capacitor (reactor), transformer tap settings and generator voltages are utilized. Also the developed system herein can be used to minimize control action taken or generator fuel cost according to the user's option on the weighting factor. The results of a case study are also presented.

• New & Renewable Energy
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• v.8 no.1
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• pp.8-17
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• 2012

The Korean government pushed ahead various policies to disseminate photovoltaic (PV), wind power, small hydro, bio-fuel, etc. Renewable energy system (RES) budget of the Korean government increased from 118 billion won of 2003 to 876.6 billion won of 2010. The R&D budgetary supports for RES increased by 6.8 times in the period 2003-2010. It is necessary to confirm RES budget expenditure that renewable energy promotion policy makes good performance evaluated in quantity level. This paper made Input-Output Table 2009 contains photovoltaic power generation equipment industry as a dependent sector and analyzed induced production effect by demand of photovoltaic power generation equipment industry. From the empirical analysis result, additional demand in photovoltaic power generation equipment induced 1.932 times of induced production in Korea. Each of industry sector has positive induced production from the additional demand in photovoltaic power generation equipment. Renewable energy promotion in photovoltaic power generation is considered together with industry policy as the option to sustain economic growth.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.732-739
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• 2011

A fuel cell/secondary battery hybrid power generation system could extend well beyond the efficiency and interoperability of the conventional diesel generator. The suggested power source system consists of 2.3 kW class PEMFC, 100 Ah lithium polymer battery, and two DC/DC converters by serial connection type. It was known that interoperability of sub-systems is the key factor for stable and optimal control of the hybrid power generation system. The modeling and simulation methods have been proposed to reduce the number of configurations and performance tests for components selection and select the optimized control condition of the power generation system. The control model for power source system is implemented based on the empirical formulation and carried out in the Matlab/Simulink environment. The results show that the simulation can be used to establish the algorism of prototype and increase the durability of the power source system.