• Environmental and Resource Economics Review
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• v.30 no.4
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• pp.557-579
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• 2021

Collective energy is an intermediate stage in energy conversion and has a great influence on the power structure as a distributed power source. However, the problem of the collective energy business has recently emerged due to the worsening profitability of some collective energy operators. This study measured the technical efficiency of major operators through the estimation of the production efficiency of Korean collective energy operators, and based on this, we looked at ways to improve the profit structure of operators. After collecting detailed data from 16 collective energy operators between 2016 and 2019, the production efficiency of operators was estimated using the panel stochastic frontier model. As a result of the estimation, combined steam power operators showed the highest production efficiency and reverse CHP operators showed the lowest efficiency. Furthermore, as a result of examining the factors influencing profitability, it was confirmed that production efficiency has a positive effect on overall profitability. However, businesses with a high proportion of heat production, such as small district electricity operators, profitability was lower. This phenomenon is due to the structural limitations of the current heat sales market. Hence, the adjustment of the heat sales unit price is necessary to improve profitability of collective energy operators.

• Journal of Korea Port Economic Association
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• v.27 no.1
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• pp.185-212
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• 2011

The purpose of this paper is to show the empirical analysis way for measuring the seaport efficiency by using the previous radial model and the newly modified non-radial models( panel additive model, panel RAM model, and panel SBM model)with Spearman rank order correlation coefficient(SROCC) for 20 Korean ports during 11 years(1997-2007) for 1 inputs(port investment amount) and 4 outputs(Number of Ship Calls, Port Revenue, Customer Satisfaction Score for Port Service and Container Cargo Throughput). The main empirical results of this paper are as follows. First, consistency ratio of SROCC in terms of efficiency scores between radial and panel Additive model was over about 76% and overall consistency ratio was about 71.6%. Second, an efficiency of panel RAM model was higher than that of radial model with similarity. However, panel SBM model shows the very similar efficiency scores with panel radial model. Third, the slack size of radial model is smaller compared to non-radial model. Models' ranking orders in terms of efficiency scores, number of efficient ports are panel RAM model, panel SBM model, and radial model. The order from the minimum efficiency scores was the same order like just before. The policy implication to the Korean seaports and planner is that Korean seaports should introduce the new methods like non-radial models(panel additive model, panel RAM model, and panel SBM model) for measuring the port performance.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.227-230
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• 2004

본 연구에서는 유류오염토양 세척유출수내 미세토사의 효율적 제거를 위한 최적의 방안 및 적용 운전 조건을 도출하고자 하였다. 응집제를 주입하지 않은 blank 실험결과, 광운대학교 토양 세척유출수는 pH 7～12의 범위에서 65～75%의 효율을 나타내었고, 우이천 하천퇴적 토양 세척유출수는 pH 7～11의 범위에서 30% 안팎의, pH 12에서는 70% 정도의 낮은 효율을 나타내었다. pH 13에서는 두 가지 세척유출수에서 각각 91%, 85%의 효율을 나타내었다. 응집ㆍ침전 실험 결과, 광운대학교 토양 세척유출수는 FeC13, alum, PAC을 적용하였을 때 대체로 99% 이상의 효율을 보였으나, PAM을 적용하였을 때는 pH 13에서만 약 95%의 효율을 보였을 뿐 pH 7～12의 범위에서는 50～70%의 낮은 효율을 보였다. 우이천 하천퇴적 토양 세척유출수는 alum과 PAC을 적용하였을 때 대체로 90% 이상의 효율을 나타내었으나, FeC13와 PAM을 적용하였을 때는 pH 13일 경우에서만 98%이상의 효율을 보였을 뿐 다른 pH조건에서는 대체로 60%이하의 효율을 보였다. 두 가지 세척유출수에 대하여 높은 효율을 보인 alum과 PAC의 경제성을 비교해본 결과 같은 양의 세척유출수를 응집처리 할 경우 PAC에 비하여 alum을 적용하였을 때 적은 비용이 소요되었다. 따라서 alum이 효율성과 경제성에서 가장 우수함을 알 수 있었다.

• Journal of Korea Port Economic Association
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• v.33 no.4
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• pp.135-148
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• 2017

This study fist raises the following research question. How does the port congestion affect port operational efficiency? To answer the question, this study adopts slacks based measure data envelopment analysis (SBM-DEA) model to analyze the efficiency of port considering the congestion. As a result of the DEA-CCR(Chanres, Cooper and Rhodes) model, both Busan(2011) and Ulsan(2011) are the most efficient decision making units(DMUs). As a result of the DEA-BCC(Banker, Chanrnes, and Cooper) model, Busan(2011), Ulsan(2011), Ulsan(2012), Busan(2012), and Yeosu Gwangyang(2012) are the most efficient DMUs. As a result of SBM-DEA model, Ulsan(2012), Busan(2011), Busan(2012), Incheon(2011), and Ulsan(2011) are the most efficient DMUs considering the port congestion. The result of DEA-CCR BCC model is not identical with the result of SBM-DEA model analysis. It means the port congestion does less affect the port operational efficiency. Should the number of the vessels with the port congestion minimize, Incheon and Yeosu Gwangyang port could save lots of the port congestion cost for a total of three years.

• Journal of Korea Water Resources Association
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• v.53 no.spc1
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• pp.731-742
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• 2020

The purpose of this study was to examine the efficiency of local waters in Chungnam. The Statistics of Waterworks data released by the Ministry of Environment were analyzed by DEA (Data Envelopment Analysis). DEA is a relatively data oriented approach to evaluate the performance of a set of peer entities called decision making units which convert multiple inputs into multiple outputs. It was possible to obtain significant results on the regional efficiency of local waters in 15 regional, the causes and degree of their inefficiency and what areas one could refer to. It was evaluated that the efficiency of Gun regional was insufficient, and it was found that an improvement policy was needed to improve productivity. This study provided implications for entire local waters operation in Chungnam.

• Journal of Environmental Policy
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• v.10 no.2
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• pp.61-92
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• 2011

We analyzed the efficiency of environment investments by taking examples of central government's environmental investment (CGEI hereafter) and investment in prevention of environmental pollution (IPEP hereafter). We expanded the scope of existing studies by decomposing the internal rate of return (IRR hereafter) and present value of benefit (Bpv hereafter) into variable cost (VC hereafter) reduction, investment cost reduction (STC-VC hereafter), and rent. And we found that Bpv checks only the magnitude of benefit, while IRR indicates the existence of efficiency by investigating short-run total cost (STC hereafter) reduction and rent. Finally, by analyzing investment efficiency and changing benefit with respect to CGEI and IPEP through the investment efficiency methodology that compares IRR with market interest rate, we executed retrospective benefit-cost analysis. Accordingly, CGEI and IPEP are not efficient. However, IPEP is even more inefficient than CGEI.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.309-321
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• 2021

While total sales of broadcasting business have been increasing, terrestrial broadcasters' sales are stagnant and comprehensive programming program providers(PPs)' sales are increasing. The purpose of this study is to derive implications by analyzing the relative efficiency and super-efficiency of domestic broadcasters in such an asymmetric situation. In this study, we use input and output data of three central terrestrial broadcasters and four comprehensive programming PPs from 2012 to 2019. For the analysis, Additive DEA model and Additive super-efficiency DEA model are used with the assumption of VRS condition since the broadcasting industry is characterized by economies of scale. As a result, we find out that the input excess of tangible assets is the most decisive cause of inefficiency that reduces the efficiency of central terrestrial broadcasters. On the other hand, for the comprehensive programming PPs, the input excess of tangible assets and the output shortfall of total sales are important factors of inefficiency.

• Convergence Security Journal
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• v.23 no.2
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• pp.95-102
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• 2023

The purpose of this paper was to confirm the operational level of the military department of universities, which plays a key role in the officer training process, through empirical research and confirm meaningful results for improvement. There are 11 university military departments operated through the Army, agreements, and semi-agreement, and the Data Envelopment Analysis (DEA) was applied from the perspective of resource input and performance for each university's military department operation to analyze relative efficiency and confirm specific directions for improvement. As a result of operational efficiency analysis, 6 DMUs (Decsision Making Unit) were found to be efficient in the BCC model out of 11 DMUs, and the evaluation results could be confirmed through classification of efficient and inefficient groups through data capture analysis. This paper may be of practical value in that it checks the efficiency of the comparative university military departments and confirms specific information for development through the DEA-Additive model that reflects several evaluation factors at once. Through this, the operators of each university's military department are admitted.

• Journal of Environmental Policy
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• v.12 no.4
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• pp.23-44
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• 2013

Climate change affects human and natural environment. Many countries, including Korea, are trying to develop climate change adaptation strategies to minimize adverse impacts of climate change. To deal with climate change efficiently, decisions have to be made among many options. The objectives of this paper is to analyzes methodologies for prioritizing climate change adaptation measures. Each methodology has strength and weakness and information requirements are differ. We find multi-criteria analysis is one of useful tools considering current level of understanding on climate change adaptation. We suggest climate change risks(timing, likelihood, intensity of climate change impacts), feasibility of policy (equity, main-streaming, democracy), effectiveness (economic effectiveness, co-benefits, propagation effects) of adaptation measures as main evaluation criteria of prioritization.

• Journal of the Korean Society for information Management
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• v.32 no.3
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• pp.277-293
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• 2015

This study examined the relative retrieval effectiveness after relevance feedback between two systems (Title/Abstract and Full-text) using four different sets of relevance judgment. Four relevance levels (not relevant, marginally relevant, relevant, highly relevant) are also used, each of which is determined by referees giving a relevance score to documents. This study also investigated how much the average precision was improved after relevance feedback when "marginally relevant" documents are included in the relevant class with the Title/Abstract system, and with the Full-text retrieval system as well. It is found that the Title/Abstract system benefited from relevance feedback with the marginally relevant documents. In case of the Title/Abstract system, the higher percentage of improvement was consistently obtained when including the marginally relevant documents in the relevance class, however the result was vice versa in case of the Full-text retrieval system. It implied that the marginally relevant documents in the relevant class had caused noises in the Full-text retrieval system.