• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.3
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• pp.75-90
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• 1998

The improper use of input and output factors in DEA has a critical and negative impact on the efficiency measurement and the discernment of decision making units(DMUs) : hence the proper selection Process of the factors should precede the actual applications of DEA. In this paper, we propose a new approach to selecting proper factors based on Tofallis' partial efficiency evaluation method(1996). With the approach, the factors aye clustered by measuring their respective partial efficiencies and analyzing the rank correlations of them. The method and procedure we propose in this paper are then applied to measure the efficiencies of the public libraries in Seoul District area, and the results show that the proposed approach can provide meaningful information to improve discernment of the DMUs while using less number of input factors (and less information). The proposed method can be effectively used in the situation where the number of the DMUs to be considered is relatively small compared to the number of available input and output factors, which usually lessens the power to identify the inefficient units in DEA.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.1
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• pp.29-43
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• 2012

We design a DEA-AR model using multiple regression analysis with new methods which limit weights. When there are multiple input and single output variables, our model can be used, and the weights of input variables use the regression coefficient and coefficient of determination. To verify the effectiveness of the new model, we evaluate the efficiency of the Regional Corporations in Korea. Accordance with statistical analysis, it proved that there is no difference between the efficiency value of the DEA-AR using AHP and our DEA-AR model. Our model can be applied to a lot of research by substituting DEA-AR model relying on AHP in the future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.7
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• pp.529-536
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• 2007

The perforated type element for a heat recovery ventilation system has been studied to improve the performance. Four holes of diameter of 6mm are punched out for each flow channel to break the boundary layer development and increase the turbulence. KS cooling and heating conditions and test procedures are applied for study. The efficiencies are compared to those of the typical element with smooth surface. For cooling operations, the temperature, latent and enthalpy efficiencies increase 2.5%, 18% and 8%, respectively. For heating operations, the temperature, latent and enthalpy efficiencies increase 3%, 5% and 3.2%, respectively.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.93-104
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• 2000

Passive agents participate in team activities passively, that is, only upon requst, whereas active agents involve themselves voluntarily. Teams composed of active agents are generally believed to perform better than those with passive agents. In this paper, by using a computational simulation model we examine the effect of agent activeness on the efficiency of decision-making teams that access different amout of information. "Team-Soar" is a computational fraemwork that consists of a group of interconnected individual Al agents (i.e., Soar). A simulation experiment using Tearm-Soar was performed. Results of the simulation provide valuable insights on the roles of agent activeness. For example, the impact of having more active agents becomes more sigfniciant as the amout of information to process increases and when the team decision efficiency is important. Some of the results are counter-intultive and therefore provides an opportunity to understand the roles of the agnet activeness more deeply. For instance, the simulation results reveal that having more active agents did not always enhance team efficiency. Conclusively, the simulation experiment demonstrates how computational models contribute to the research of agents social characteristics.teristics.

• Journal of the Korean Operations Research and Management Science Society
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• v.40 no.1
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• pp.91-116
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• 2015

This study aims to provide public sectors with eco-efficiency information. To implement the purposes of the study, environmental and economic variables of Eco-Efficiency were identified through decision tree model, then the relative Eco-Efficiencies of 243 public sectors were evaluated through input-oriented DEA (Data Envelopment Analysis) model. Specifically, the amount of public purchasing per a staff and the amount of energy use per a staff were considered as input factors. Sales per a staff was considered as output factor. The result shows that most of the public sectors (94.2%) were evaluated as "inefficient" taking into consideration of average value, 0.501 from market-based public corporations, 0.288 from local public corporations, 0.28 from quasi-market-based public corporations, 0.269 from fund-management-based quasi-governmental institutions, 0.09 from non-classified public institutions, and 0.078 from commissioned-service-based quasi-governmental institutions. Furthermore, it is possible to establish a plan for internal Eco-Efficiency improvement based on information of the reference set. In order to improve the Eco-Efficiency in the public sectors in the long term, environmental impacts of the overall public sectors' operations (e.g., energy saving, water saving, waste reduction, and purchasing of green products) needs to be properly proposed in consideration of BSC (Balanced Scorecard) indicators of public sectors.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.977-985
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• 2011

Airborne separation assurance is a key requirement for Free Flight Airspace operations, This paper study the feasibility of airborne separation assurance for free flight Airspaces operations by evaluating the efficiency measurement models. Three qualitatively different methods are utilized; one based Ground and Air conflict probability model, other based Dynamic Density model. the other based Direct operating cost model. The evaluation is Direct Operating Cost model and Two metrics are utilized for the efficiency measurements; airborne separation assurance performed quite well in the Free Flight evaluation; (1) 2 scenario of the conflict situations are resolved; (2) The MD-80 flight peformed separation assurance and efficiency, Not only appling for geometric method algorithm is more efficiently than potential method, but also the most efficiently geometric combined method.

• Tunnel and Underground Space
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• v.32 no.4
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• pp.254-271
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• 2022

The performance of truck haulage operations in an underground mine was evaluated using the time usage model and key performance indicators (KPIs) proposed by Global Mining Guidelines Group (GMG). An underground mine that mainly produces iron and titanium iron was selected as a study area, and truck haulage data were collected using Bluetooth beacons and tablet PCs. The collected data were analyzed to identify unit operations, activities, events, and required time of truck haulage operations, and time categories were classified based on the time usage model. The performance of the haulage operations was evaluated using nine indicators in terms of availability, utilization, and effectiveness. As a result, in terms of availability, uptime was 33.9%, physical availability was 95.7%, and mechanical availability was 94.9%. In the case of utilization, use of availability was 83.1%, asset utilization was 28.1%, and operating and effective utilization were 79.6% and 77.7%, respectively. Also, in terms of efficiency, operating efficiency was high at 97.6%, and production effectiveness was found to be 49%.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.1
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• pp.113-119
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• 2015

Recently, even though firefighting operations are supposed to be incorporated into single body IAW restructuring of the government organizations, in terms of efficiency it is still difficult to find any significant improvements due to the centrally and locally segregated operating bodies and also, as with organizations firefighting manpowers are divided nationally and locally, which results in differing firefighting functioning. Although governments firefighting bodies are changed to operate better, there are always limitations in firefighting operations. This study explores firefighting organizations, manpower, equipment and operations itself to optimize firefighting operations, and ultimately, to provide the future-oriented functions and roles of the firefighting aviation corps.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.4
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• pp.1-8
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• 2022

In this study, we propose trajectory-based arrival management using CDO (Continuos Descent Operations). The operational procedures with TBO (Trajectory-Based Operations) concept were established to allow aircraft and ground system to share the trajectories with each other in real time. The proposed operational concept was validated in the air traffic control simulation environment, which consists of controller working position, pseudo pilot system, air traffic generation system, and controllers' decision support system for arrival management using CDO. Simulation results compared with actual flight data indicate that proposed concept could improve the efficiency of traffic flow management in terms of total descending time and fuel consumption. And it was confirmed that if there is a system that can share and utilize the synchronized trajectory, it can be helpful to control arrival aircraft and apply CDO concept.

• Journal of the Korean Dietetic Association
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• v.8 no.4
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• pp.387-397
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• 2002

Foodservice information systems management practices were assessed in hospital foodservice operations. A total of 46 dietetic departments were responded for the study and their practices of foodservice information systems were analyzed. The respondents were questioned about general characteristics of respondents as well as hospital foodservices implementation status of information systems. Statistical data analysis was completed using the SPSS package program for descriptive analysis, factor analysis, t-test and ANOVA test. 43.2% of total respondents gained informations by benchmarking of other hospital foodservice operations, but 7.8% gained through career education. They expected the enhanced efficiency of their tasks through implementing information systems. Based on factor analysis, information systems were divided into 6 management areas such as database management, meal management, nutrition management, purchasing management, production management and foodservice management. The average implementing scores were : database management 3.77, meal management 3.26, nutrition management 3.52, purchasing management 3.26, production management 2.73 and foodservice management 3.70 (score 1 indicates very poor and score 5 is very good). Among database management areas, standard recipe database and food item specifications database build-up scores(3.91) were relatively very high, but meal assessment and foodservice management reporting scores(2.43) were very low. The results suggest that it is necessary to build up automated foodservice management reporting system for the improvement of efficiency and productivity of operational tasks.