• Communications for Statistical Applications and Methods
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• 제24권3호
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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.

• 한국산업정보학회논문지
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• 제19권2호
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• pp.93-103
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• 2014

본 논문은 Hall(1990)과 Basu(1997)의 모형에 근거하여 생산성추정모형을 설정하고, 분석기간 1975:1-2010:4에 걸쳐서 의료서비스 산업에 있어서 생산성을 5개의 형태로 측정한 다음 생산성의 순환성을 밝히고 실질임금과 측정된 생산성과의 연관성을 분석하였다. 시장지배력을 제거하고 규모의 보수를 고려하여 솔로우잔차항을 측정한 결과 의료서비스 산업에서 시장 지배력이 크게 존재하고 있으며 생산측면에서 규모의 보수가 크게 존재하고 있다는 것이 확인 되었다. 시장지배력을 제거하는 경우 솔로우잔차항은 강한 경기순행성에서 강한 경기역행성으로 전환되었음을 볼 수 있다. 이러한 결과는 시장지배력을 나타내는 대리변수인 산업별 마크업의 경기역행적인 특성이 작용하고 있는 것으로 추론할 수 있다. 또한 실질임금증가율과 생산성과의 관계를 분석할 때 생산성지표로서 노동생산성이나 본래의 솔로우잔차항 또는 시장지배력을 제거한 총비용에 근거한 솔로우잔차항이 적정한 지표로 활용될 수 있음을 밝히고 있다.

• 한국산학기술학회논문지
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• 제9권6호
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• pp.1569-1573
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• 2008

본 논문은 핵발전소 증기발생기의 초음파 비파괴 검사용 프로그램 개발에 관한 것이다. 개발된 프로그램은 A, B, C, D-스캔과 같은 고전적인 해석방법뿐만 아니라 3차원 영상처리 기법을 이용하여 증기발생기 내부에 발생한 결함을 해석하고 검출할 수 있다. 결함의 3차원 영상은 핵발전소의 파이프라인으로부터 얻어진 1차원 초음파 데이터를 EMD(Empirical Mode Decomposition)로 분석해 결함의 위치를 구하고 voxel을 이용하여 구현하였다. 얻어진 3차원 영상은 2차원 해석방법을 사용하지 않더라도 결함의 위치, 형태, 크기 등과 같은 유용한 정보를 얻는데 용이하다. 개발된 프로그램은 이미 결함의 위치 및 모양, 크기 등을 알고 있는 시편의 측정에 사용하여 프로그램의 정확성을 검증하였고, 3차원 영상으로 결함의 입체적 모양을 구현하였다.

• 한국콘텐츠학회논문지
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• 제20권12호
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• pp.13-22
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• 2020

본 연구는 영화 분야 크라우드펀딩 성공요인 실증분석을 위하여 국내 크라우드펀딩 플랫폼 텀블벅의 영화 프로젝트 중, 총 583개 데이터를 수집하여 분석을 진행하였다. 구체적으로 목표 금액, 게시글 정보, 리워드 선택 옵션, 창작자 펀딩 파워, 에디터 추천 여부, 창작자 콘텐츠 파워, 영화 유형, 코멘트 수, 댓글 수, SNS 정보 수 등 10개의 독립변인을 설정하고 크라우드펀딩 최종 달성률을 종속변인으로 설정하여 영향관계를 검증하였다. 연구 결과 영화 크라우드펀딩 프로젝트 달성률에 목표금액, 텍스트 수, 동영상 수, 에디터 추천 여부, 후원자 댓글 수, SNS 정보 수가 유의미한 영향을 미치는 것으로 드러났다. 본 연구는 '에디터 추천 여부'와 '창작자의 SNS 정보 수' 변인을 크라우드펀딩 연구 분야에 접목시켜 두 변인 모두 크라우드펀딩 달성률에 정(+)적인 영향을 미치는 것을 검증했다는 점에서 시사점을 가진다.

• The Journal of Asian Finance, Economics and Business
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• 제9권5호
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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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• 제56권4호
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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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• 제2권4호
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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.

• 대한전기학회논문지
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• 제39권8호
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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.

• 신재생에너지
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• 제8권1호
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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.

• 한국군사과학기술학회지
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• 제14권4호
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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.