• Environmental and Resource Economics Review
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• v.14 no.3
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• pp.595-626
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• 2005

The purpose of this paper is to estimate technical efficiency, scale efficiency, and environmental efficiency by income level of Korean farms, and analyze the factors to decide three efficiencies. Depending on the non-parametric methods, we estimate technical using inputs and outputs of total farms without assuming of goods or behavior of optimization. The average technical efficiency of total firms under constant return to scale and strong disposability is 0.437. The technical inefficiency was caused by 47.7% in pure technical inefficiency, 11.3% in scale failure, and 3.2% in environmental inefficiency. The number of firms under increasing return to scale occupied almost 70% and 27% of total firms respectively. Higher are income class, middle debt & long debt per asset, and N effluents per cultural land, higher technical efficiency. The increases of BOD discharges per cultural land and machines per cultural land deteriorate environmental efficiency.

• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.165-173
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• 2022

Recently, competition to provide specialized services for the information and communications industry has accelerated in terms of future technology and investment strategy of the Fourth Industrial Revolution. Technological innovations related to information and communications can be seen as increasing productivity, creating added value for companies, and playing a pivotal role in the development of economic growth. Therefore, efficient management of the information and communications industry is important. This study analyzes management efficiency stones for the top 30% of KOSDAQ-listed information and communications companies using dea, presents projected values of companies for efficient operation, and confirms benchmarking company references. We evaluated CCR efficiency, BCC efficiency, ranking, Scale Efficiency(SE), and Return To Scale (RTS) of KOSDAQ-listed information and communications businesses. The analysis showed CCR efficiency of 1, 14 companies, and 1 BCC efficiency, and Nanatan companies were analyzed as ten companies. Scale yield was analyzed by the IRS as four companies, 13 CRS and 13 DRS companies.

• Journal of Digital Convergence
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• v.11 no.5
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• pp.119-133
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• 2013

This study aims to provide power generating plants with eco-efficiency information. To implement the purposes, of study, both DEA(Data, Envelopment Analysis) model and interview were incorporated in terms of methodologies. To analyze the managerial efficiency, total labor cost and number of employees were considered as input factors. CO2, NOx, and water also were considered as input factors to analyze eco-efficiency. Both annual total power product and annual total revenue were used as output factors. CRS(Constant Return to Scale) and VRS(Variable Return to) model were facilitated in this analysis. According to the findings, most of the power plants were evaluated as 'Efficient'' taking into consideration of average value, both 0.928 from CCR model and 0.969 from VRS model. 7 DMUs including DMU3 and DMU12 are efficient out of 35 DMUs relatively, other DMUs are inefficient. For results of inefficient output factors distribution, it was found that inefficiency for NOx was marked relatively higher than CO2. In order to improve the eco-efficiency in the power plants in the long term, the target amount of Co2 as well as NOx reduction needs to be properly proposed in consideration of particularity of power plants. In the long run, renewable energy, alternative fuels should be adapted to reduce the eco-inefficient.

• Journal of Navigation and Port Research
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• v.34 no.9
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• pp.719-726
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• 2010

As the competition among the container terminals in Korea has become increasingly fierce, every terminal is striving to increase its investments constantly and lower its operational costs in order to maintain the competitive edge and provide satisfactory services to terminal users. The unreasoning behavior, however, has induced that substantial waste and inefficiency exists in container terminal production. Therefore, it is of great importance for the terminal to know whether it has fully used its existing infrastructures and that output has been maximized given the input. From this perspective, data envelopment analysis (DEA) provides a more appropriate benchmark. This study applies three models of DEA to acquire a variety of analytical results about the operational efficiency to the Korean container terminals. According to efficiency value analysis, this study first finds the reason of inefficiency. It is followed by identification of the potential areas of improvement for inefficient terminals by applying slack variable method and giving the projection results. Finally, return to scale approach is used to assess whether each terminal is in a state of increasing, decreasing, or constant return to scale. The results of this study can provide terminal managers with insight into resource allocation and optimization of the operating performance.

• Journal of Korean Foot and Ankle Society
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• v.23 no.2
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• pp.52-57
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• 2019

Purpose: An ingrown nail is common in military trainees who are exposed to highly demanding activities. Although the matrixectomy procedure has been the main treatment modality, several drawbacks may follow after the procedure, such as infection, periostitis, and continued pain that causes a delayed return to duty. This study examined the outcomes of a simple partial nail extraction with the hypothesis that this procedure may bring an earlier return to duty, lower the perioperative complications, and produce a comparable recurrence rate. Materials and Methods: The medical records of patients who had surgical treatment for an ingrown nail in the authors' institution between April 2016 and December 2017 were reviewed retrospectively. Under the inclusion and exclusion criteria, 28 patients with a simple partial nail extraction (group A) and 29 patients with a partial nail extraction with matrixectomy (group B) were investigated. As the clinical outcome, the visual analogue scale (VAS) and satisfaction score, time to return to duty, complications, and recurrence rate were checked and compared between the groups. Results: The VAS scores of group B were significantly higher during the first (p<0.001) and second (p=0.026) follow-up week than group A. The time to return to duty was shorter in group A (7.8 days) than group B (10.1 days), and this difference was significant (p<0.001). Group B had five patients with complications, whereas group A had none (p=0.028). No differences in the recurrence rate (p=0.197) and patient satisfaction (p=0.764) were found between the groups. Conclusion: In this study, simple partial nail extraction in military trainees resulted in lower postoperative pain, lower complication rates, and earlier return to duty than the procedure with matrixectomy. Military trainees are temporarily exposed to highly demanding activities. Thus, a satisfactory outcome would be expected with simple partial nail extraction without performing a radical procedure, such as a matrixectomy.

• The Korean Journal of Pain
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• v.35 no.1
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• pp.97-105
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• 2022

Background: Percutaneous transforaminal endoscopic discectomy (PTED) has been widely used in the treatment of lumbar degenerative diseases. Epidural injection of steroids can reduce the incidence and duration of postoperative pain in a short period of time. Although steroids are widely believed to reduce the effect of surgical trauma, the observation indicators are not uniform, especially the long-term effects, so the problem remains controversial. Therefore, the purpose of this paper was to evaluate the efficacy of epidural steroids following PTED. Methods: We searched PubMed, Embase, and the Cochrane Database from 1980 to June 2021 to identify randomized and non-randomized controlled trials comparing epidural steroids and saline alone following PTED. The primary outcomes included postoperative pain at least 6 months as assessed using a visual analogue scale (VAS) and the Oswestry Disability Index (ODI). The secondary outcomes included length of hospital stay and the time of return to work. Results: A total of 451 patients were included in three randomized and two non-randomized controlled trials. The primary outcomes, including VAS and ODI scores, did not differ significantly between epidural steroids following PTED and saline alone. There were no significant intergroup differences in length of hospital stay. Epidural steroids were shown to be superior in terms of the time to return to work (P < 0.001). Conclusions: Intraoperative epidural steroids did not provide significant benefits, leg pain control, improvement in ODI scores, and length of stay in the hospital, but it can enable the patient to return to work faster.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.905-912
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• 2006

In this paper, simulation methods of the system dynamics model developed by Das et al. (1997) for activated-sludge wastewater treatment plants are illustrated in an attempt to determine the operating rules and the policies related to capacity expansion of an activated-sludge wastewater treatment plant. For existing conditions, the analyses were performed by varying activated-sludge return rate to observe changes in effluent water quality and treatment efficiency. The effluent water quality is also analyzed for various average daily inflow conditions and activated-sludge return rates. As a result, without expanding the aeration tank, maximum average daily inflow that can satisfy the effluent water quality standard of BOD $0.02kg/m^3$ was determined as $2,840m^3/hr$, subject to 100% of activated-sludge return rate while other factors remain constant. When the activated-sludge return rate is less than 100%, expansion of the aeration tank is necessary and minimum sizes of the aeration tank to satisfy the effluent water quality standard were determined for various activated-sludge return rates. In addition, the total operating and maintenance as well as unit treatment cost regression equations for activated-sludge wastewater treatment plants are suggested by using the cost data that are obtained from Water and Wastewater Division, Ministry of Environment. The regression analyses showed that the economies of scale phenomena exist in the operating and maintenance costs of activated-sludge wastewater treatment plants.

• Journal of Engineering Education Research
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• v.27 no.1
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• pp.50-62
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• 2024

This study examined how emotion regulation strategies specifically function in the interpersonal conflict coping strategies of engineering students. For this purpose, a interpersonal conflict coping strategies and emotion regulation strategies scale was used for 548 engineering students. Multiple regression analysis was conducted. Among the emotion regulation strategies, the "return to body" strategy was related to understanding, validation, focusing, and the "stop action" strategy. In particular, the "stop action" strategy was closely related only to the "return to body" strategy. Among interpersonal conflict coping strategies, the dominating strategy used both positive emotion regulation strategies, such as high refocus on planning, and negative emotion regulation strategies, such as other-blame. Additionally, among negative conflict coping strategies, it was confirmed that both aggression and negative emotional expression, which seem to have similar attributes, share a common feature of having high difficulty in emotional clarity. However, in the case of negative emotional expression, it is characterized by a lack of putting into perspective and high other-blame. On the other hand, the agression strategy seemed to have different characteristics, such as high self-blame and low return to body. By investigating the relationship between interpersonal conflict coping strategies and specific emotion regulation strategies, this study provides implications for education and intervention on which specific emotion regulation strategies need to be cultivated for engineering students to improve their interpersonal conflict resolution capabilities.

• Journal of Soil and Groundwater Environment
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• v.15 no.4
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• pp.21-29
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• 2010

As the target area of this study, the coal mine site of Dongwon Sabuk mine.,ltd. is located in the remote mountainous region. To purify the acid mine water contaminated with heavy metals, a pilot-scale plant was built at the surrounded area of a mine shaft and operated to simulate active treatment system that could not only possibly setup the facility in a small available area, but also has a high efficiency. According to the various conditions of basin sequence, existence of sludge return, and lime injection position, six different types of treatment series were investigated in terms of treatment efficiency. As a result, the aluminum concentrations of the most effluents were in the range of 0.005~0.030 mg/L, which was too low to compare. The manganese concentration in the treated water were in the range of 3~9 mg/L, not following any regular trend. As found in the results of iron concentration, the case of addition of oxidation and sludge return steps showed higher efficiency than the others. As a standpoint of the installation of full-scale physicochemical treatment facility, the experimental results showed that the batch of oxidation and high density sludge return processes are existed and neutralization was followed by oxidation, had a stable treatment efficiency.

• Journal of Information Technology Services
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• v.15 no.2
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• pp.51-63
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• 2016

In this study, we conducted a comparative analysis of R&D investment efficiency and operational efficiency of IT firms using Data Envelopment Analysis (DEA). We categorized thirteen sample firms into two groups-IT manufacturing and IT service-after an extensive literature review on IT industry classification. We adopted an output-oriented two-stage DEA model suggested by Banker et al. (1984) with total asset and R&D investment as input variables. Then, we constructed investment efficiency and operational efficiency by using Return on Equity (ROE) and Return on Asset (ROA) as intervening variables and operating income and Earnings Per Share (EPS) as output variables. The outcome of the analysis is summarized as follows. First of all, IT manufacturing firms were more efficient (57% on average) than IT service firms. To be specific, IT service firms showed decreasing returns to scale (DRS) with diseconomy of scale. In contrast, IT service firms showed higher operational efficiency (81.5% on average) than IT manufacturing firms. Also, we conducted a Mann-Whitney U test to compare the output of IT service firms and IT manufacturing firms. Lastly, we found a negative correlation ($R^2$ = -.754) between R&D investment efficiency and operational efficiency which infers the trade-off between two constructs