• Nuclear Engineering and Technology
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• 제51권8호
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• pp.1970-1977
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• 2019

Understanding the irradiation hardening effect of structural steels under various irradiation conditions plays an important role in developing advanced nuclear systems. Such being the case, a crystal plasticity model for body-centered cubic (BCC) crystal based on the density of dislocations and irradiation defects is summarized and numerically implemented in this paper. Based on this model, nano-indentation hardness of Chinese A508-3 steels with ion irradiation is calculated. Very good agreement is observed between simulation and experimental data of several different irradiation doses subjected to various operating temperatures, from which, it can be concluded that indentation hardness increases with increasing irradiation dose at both room temperature and high temperature. Consequently, the validity of this model has been proved properly, and furthermore, the model established in this paper could guide the study of irradiation hardening effect and temperature effect to some extent.

• 산업경영시스템학회지
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• 제41권3호
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• pp.61-71
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• 2018

The purpose of this study is to analyze the efficiencies of project management offices in large information system construction projects using the data envelopment analysis. In addition, we tried to estimate the confidence interval of those efficiencies using bootstrap DEA to give a statistical meaning. The efficiency by the CCR model is analyzed as eight project management offices are fully efficient and 22 project management offices are inefficient. On the other hand, there are 15 project management offices are fully efficient, but 15 project management offices are inefficient in the BCC model. As the result of the scale efficiencies, of the inefficient project management offices, 13 project management offices are inefficient in scale. It is possible to eliminate the inefficiency in the CCR model by improving their project performances. And, the nine project management offices showed that the inefficiency was due to pure technical efficiency, and these companies should look for various improvements such as improvement of project execution system and project management process. In order that the inefficient project management offices be efficient, it is analyzed that more efforts must be made for on-budget and on-time as a result of examining the potential improvement potentials of inefficient project management offices.

• 한국콘텐츠학회논문지
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• 제19권5호
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• pp.64-73
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• 2019

본 연구는 전문건설업체의 경쟁력을 평가하기 위해 DEA모형을 활용하여 효율성을 분석하였다. 분석대상기업은 전문건설업 상장업체와 외감업체로 2010년부터 2017년까지 연속자료가 존재하는 300개 기업을 대상으로 하였다. 특히, 전문건설업 유형별 효율성을 비교, 분석하여 그 시사점을 찾는데 중점을 두었다. 의미 있는 분석결과는 다음과 같다. 첫째, 전문건설업체의 효율성은 전반적으로 종합건설업 등과 비교하면 효율성 값이 낮게 분석되었다. 둘째, 전문건설업 유형별 효율성은 시설물축조 및 해체 전문공사업이 가장 높게 나타났다. 이는 해당 업종인 철근 콘크리트공사업, 비계 구조물해체공사업 등이 전문건설업 내에서 상대적으로 효율적임을 의미한다. 셋째, 전문건설업 효율성은 건설경기에 영향을 받는다. 건설경기가 확장국면에 있을 때는 효율성 값이 높고, 수축국면에서는 낮은 효율성 값을 나타내었다. 마지막으로 규모수익성 분석에서 전문건설업은 DRS로 분석되는 경우가 가장 많았다. 이는 규모 확대보다 규모 축소를 통해 기업의 효율성을 높이는 것이 바람직하다는 것을 의미한다.

• 한국유기농업학회지
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• 제30권3호
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• pp.351-374
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• 2022

In recent years, the development of rice industry has been highly valued by the state. In hubei area, due to the development of the modernization and the shortage of labor, traditional way of rice cultivation methods is facing serious challenges, and economic benefits have become the decisive factor for the effective promotion and application of rice cultivation methods. According to the research results, first, in the input-side analysis, in the CCR model, D5, D12, D26, D28, D32, D36 farmers with high efficiency appear. The analysis result shows that among the 60 farmers, the average efficiency is 89%, and there is an inefficiency of 11%. In the BCC model, 14 farmers were identified as high-efficiency farmers, with an average efficiency of 0.9453. Second, in direct seeding cultivation of rice, the average scale efficiency is 0.9227, while the average pure technical efficiency is 0.9644. This shows that the effect of scale efficiency is greater than that of purely technical factors, ignoring the reasons for the low operational efficiency of direct seeding cultivation farmers. It can be predicted that with the further deepening of farmers' understanding of this planting mode, the proportion of rice direct seeding may be further expanded in the future. Relevant agricultural departments should further promote this technology to farmers, study the direct seeding technology using scientific methods, and evaluate the changes of this cultivation mode. The agricultural departments of government should concern about the climate risk assessment of direct seeding rice, the environmental impact assessment caused by the extensive use of herbicides, the application of mechanical technology in the process of direct seeding, the lodging of direct seeding rice, and other related issues.

• International Journal of Contents
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• 제4권3호
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• pp.1-9
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• 2008

The Korean life insurance industry has undergone profound changes, such as the beginning of the variable insurance in July 2001 and the bancassurance enforcement in August 2003. However, little empirical research has analyzed data that includes the bancassurance of life insurance companies operating in Korea. In response to this lack of research, this paper applies DEA (data envelopment analysis) models to measure and decompose their efficiency. We discovered that life insurance companies operating in Korea are a little different in their composition ratio of inputs and outputs, due to the increased variety of distribution channels and new products. We provided efficiency scores, return to scale, and reference frequencies. We also decomposed CCR, BCC, and SBM efficiency into scale efficiency and MIX efficiency. So, we try to investigate whether the sources of inefficiency were caused by the inefficient operation of DMU, disadvantageous conditions, the difference of the composition ratio in inputs and outputs with reference sets, or any combination of the above. Most companies in the sample display had either constant or decreasing returns to scale. The efficiency rankings were less consistent among models and efficient DMUs. In response to this problem, we used the super-efficiency model to rank them and then compared the rankings of the DMUs among the various models. It was also concluded that the availability of panel data, rather than cross-sectional data, would greatly improve the validity of the efficiency estimates.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.1162-1166
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• 2009

본 논문에서는 공간상의 한 점에 대한 연속시간 강우모델로 시간단위의 통계특성을 재현하는데 유용하다고 알려진 BLRPM(Bartlett-Lewis Rectangular Pulse Model)을 이용하여, 측우기 자료를 포함하는 서울지점의 일강우 자료를 분해하고 지속시간별로 집성하여 모의된 시단위 단기 강우의 정량적 장기변화 특성을 분석해 보았다. 모의자료의 전이확률과 발생빈도 분석결과, 측우기 관측계열(CWK)에 비해 근대 우량계 관측계열(MRG)의 무강우 지속기간은 길어지고 강우지속기간은 짧아졌음을 알 수 있다. 이는 과거에 비해 근래의 강우지속기간이 짧아졌음을 의미하고, 근래 강우량의 양적증가와 같이 고려해 보면 근래의 강우강도가 과거보다 매우 높아졌음을 증명해 준다. 1960년대 전후로 구분한 자료계열(BCC와 ACC)에 대하여 지속시간별 모의 강우량의 평균과 분산의 비(증감률)를 월별로 비교한 결과, 전반적으로 9월이 증가의 정도가 가장 컸고 8월도 비교적 큰 증가 경향을 보였다. 그러나 6월은 오히려 약간 감소한 경향을 나타냈다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제35권11호
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• pp.661-670
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• 2008

만족가능성 처리기는 모델 검증 및 임베디드 프로그램 검증과 같이 소프트웨어 공학의 여러 분야에서 활용되고 있다. 만족가능성 처리기를 활용하기 위해서는 주어진 문제를 처리기의 입력인 CNF 형식으로 변환해야 한다. 그러나 이 형식은 소스코드나 소프트웨어 모델보다 표현력이 낮기 때문에 최적화된 변환이 요구된다. 본 논문에서는 "n개에서 인접된 $k{\leq}n$개 선택" 문제를 CNF형식으로 변환하는 최적화된 기법을 제시한다. 제안된 방법을 다양한 일본 퍼즐에 적용한 결과 우수한 성능이 입증되었다. 우리가 알고 있는 한, 인접성에 대한 최적화된 CNF 변환 연구는 거의 없다.

• 수산해양교육연구
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• 제28권6호
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• pp.1629-1639
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• 2016

This study is to estimate the production efficiency of abalone aquaculture and to find its determinants utilizing the survey data of operating expenses in 2015. The first part of the analysis applied both DEA and Super-DEA for the estimation of efficiency of each aquaculture household as DMU. We used wages, feeding costs and area as inputs and annual profits and sales as outputs of the model. The second part of the study applied both Tobit and OLS for the identification of determinants of the efficiency. We investigated cost-ratio, depreciation costs, careers, value of living seeds, cleaning costs of farming ground and a ratio of 1 and 2 year-old abalone at shipment as potential determinants. The estimation results show us that the average technical efficiency, pure technical efficiency, and scale efficiency score turn out to be 72%, 81% and 85% respectively. The Super-BCC and Super-CCR models reveal their average efficiency scores as 81% and 80%. All of the variables used to identify the determinants of the efficiency. The study results suggests that the production efficiency can be improved by cleaning farming ground and hence lowering the death rate of seeds.

• 산업경영시스템학회지
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• 제36권3호
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• pp.126-132
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• 2013

In this paper, efficiencies of core technology development projects, conducted by Ministry of Trade, Industry and Energy, are compared. In the process, DEA (Data Envelopment Analysis) is utilized as a main technique for comparing efficiencies. For DEA, input oriented BCC Model is adopted with government grant, recipient expenditure, the number of participating institutions, and project duration as input factors, and the number of patents, the number of papers, and occurred sales as output factors. As a result, next generation mobile communication project turns out to be the most efficient project of all. Therefore, next generation mobile communication project should be benchmarked for the other projects to follow. However, these results should be used only for reference data since every project has a different objective and, of course, is run under a different environment.

• 대한산업공학회지
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• 제39권4호
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• pp.298-312
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• 2013

This paper compares efficiency results and performance targets for academic departments in a local private college using DEA (Data Envelopment Analysis). Because of an aging society, a smaller school-age population entering colleges, and enhanced accreditation standards by the government, colleges and universities are not recruiting and retaining sufficient students and therefore are struggling for survival. In contrast to popular four-year undergraduate universities concentrated in Seoul and its satellite cities, retaining students is critical for the survival of local private colleges in poor or remote regions. Therefore, it is very important to identify the factors involved in the retention of students in the various departments of a college. However, given the different characteristics of the departments, it is difficult to identify one unique or robust set of standards to evaluate their performance. The purpose of this paper is to maximize student retention capabilities by ensuring that additional resources are assigned to efficient DMUs, while, inefficient DMUs are given benchmarked targets. Based on previous studies and college accreditation standards, this paper presents indices to be used in evaluating the efficiency of academic departments in a college. In evaluating relative efficiency, this paper uses the output-oriented BCC model. To define target levels to be achieved for efficient DMU, a multi-stage DEA procedure is used.