• Journal of the Korea Safety Management & Science
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• v.11 no.1
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• pp.93-101
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• 2009

The use of the gas turbine for power supply is increasing recently. Accordingly, the operation and maintenance cost of the gas turbine is gradually increasing and the various efforts to cut the cost are needed. For an operation and maintenance cost saving of the gas turbine, reductions of the new purchasing charge and the reproduction repair cost of the hot gas parts are required through more effective operation and life management methods for the hot gas parts. The hot gas parts are the main parts of the gas turbine and they are replaced with the periodic. In this research, efficient operation and life management methods for the hot gas parts were presented with the cases. The methods were analyzed and verified based on real data and the cases for improving a lifetime were utilized in the field.

• Journal of the Semiconductor & Display Technology
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• v.15 no.1
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• pp.47-51
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• 2016

Human visual system infers 3D vision through stereo disparity in the stereoscopic images, and stereo visioning are recently being used in consumer electronics which has resulted in much research in the application field. Basically, stereo vision system consists of four processes, which are cost computation, cost aggregation, disparity calculation, and disparity refinement. In this paper, we present and evaluate the existing various methods, focusing on cost aggregation for stereo vision system to comparatively analyze the performance of their algorithms for a given set of resources. Experiments show that Normalized Cross Correlation and Zero-Mean Normalized Cross Correlation provide higher accuracy, however they are computationally heavy for embedded system in the real time systems. Sum of Absolute Difference and Sum of Squared Difference are more suitable selection for embedded system, but they should be required on improvement to apply to the real world system.

• Journal of Power Electronics
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• v.19 no.2
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• pp.529-539
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• 2019

The modular multilevel converter (MMC) has become a promising topology for high-voltage direct current (HVDC) transmission systems. To control a MMC system properly, the ac-side current, circulating current and submodule (SM) capacitor voltage are taken into consideration. This paper proposes a low-computation indirect model predictive control (IMPC) strategy that takes advantages of the conventional MPC and has no weighting factors. The cost function and duty cycle are introduced to minimize the tracking error of the ac-side current and to eliminate the circulating current. An optimized merge sort (OMS) algorithm is applied to keep the SM capacitor voltages balanced. The proposed IMPC strategy effectively reduces the controller complexity and computational burden. In this paper, a discrete-time mathematical model of a MMC system is developed and the duty ratio of switching state is designed. In addition, a simulation of an eleven-level MMC system based on MATLAB/Simulink and a five-level experimental setup are built to evaluate the feasibility and performance of the proposed low-computation IMPC strategy.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.2
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• pp.33-41
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• 2019

The purpose of this study is to provide a basic data for energy efficient apartment designs by analyzing electricity and gas usage according to horizontal locations of dwelling units in apartment buildings. The data for this research are collected from J-apartment complex, located at 'Wolbae' district in Daegu City. The data are sorted into several groups according to inner and outer locations, East-West locations, and the size of units. By the performance efficiency analysis, the study derives the result as follows: 1) generally inner units are more efficient than outer units. 2) West units are more efficient than East units. 3) The group that is most efficient in overall energy consumption is West-inner units (Group-D) and the least efficient group is East-outer units (Group-A1). 4) However, as units are getting bigger, inner units consumes more energy than outer units because of the gas usage patterns. The study also established cost analysis that shows the cost differences of usages for 30, 40, 50 years between each group. The result says Inner-outer location with East-West location affects a significant amount of the management costs. In terms of economic and social life of an apartment building, energy design standards need to be tuned and make the least efficient units perform as efficient as the most efficient units to optimize the social life of an apartment building.

• Water Engineering Research
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• v.2 no.4
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• pp.199-207
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• 2001

A computer-assisted desktop is developed for layout design of a concrete gravity dam on the basis of safety and economy. Using a set of regression equations, a dam layout is proposed. With reference to the regression equations and relevant input data, overall dam dimensions are determined by satisfying the stability criteria jointly under usual, unusual, and extreme loading conditions with the desired hydraulic conformity. Among several feasible alternatives, the program enables a designer to select the optimum layout, which corresponds to the minimum total cost of the structure. The method is applied to a case study to examine dimensions of proposed alternatives and to compare them with those of an existing dam.

• Journal of Korea Port Economic Association
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• v.21 no.1
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• pp.23-44
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• 2005

The port environment is rapidly changing in North-East Asia. Containerships are getting larger and faster and major shipping companies are converting to Hub & Spoke port networks on the transport systems. Therefore, the main ports in North-East Asia are intensively competing with each other for hub port. In terms of geopolitical position, locational conditions and external reputation of ports, Busan and Kwangyang ports have a comparative advantage in comparison with main ports in other countries. But in terms of weight of transshipment cargos in total container cargos, the quality of infrastructure in ports, the environment of logistics service and the cost of, using ports, Busan and Kwangyang ports have a comparative disadvantage. For the growth into hub port in North-East Asia, it is necessary that Busan and Kwangyang ports improve their weakness. Besides It is necessary to develope ports and hinterland quickly, offer uniformity of foreign investment laws and incentive systems.

• International Journal of Computer Science & Network Security
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• v.21 no.2
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• pp.181-187
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• 2021

The purpose of this study is to examine empirically the short- and long-run determinants of entrepreneurial activity in a sample of 15 the Middle East and North African economies between 2006 and 2018. More specifically, four groups of determinants are considered in the analysis, namely economic, demographic, business environment, and institutional. Given the autoregressive feature of the entrepreneurial activity process, a dynamic panel data model is estimated using the system GMM estimator. Findings reveal that unemployment, trade openness, population density, and economic freedom are the main drivers of new business creation in the short-run, while the cost and number of procedures to start a new business negatively affect entrepreneurship. In the long-run, the same findings hold true. Moreover, education and political stability and the absence of violence/terrorism positively affect entrepreneurial activity. Policy recommendations are accordingly designed.

• Journal of Korean Academic Society of Home Health Care Nursing
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• v.26 no.2
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• pp.133-144
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• 2019

Purpose: This study was conducted to verify the effectiveness of a cost management education program, focusing on the differences between a web-based group and a mobile-based group. Method: This was a quasi-experimental study using a two-group pretest-posttest design. Participants were 74 nurses in a web-based group and 69 nurses in a mobile-based group. Data were collected between January 2 and February 10. The cost management education program was configured such that the participants studied eight modules over four weeks. The after-program post-test was conducted for one week. Results: Both the web-based group and the mobile-based group showed significantly higher values for cost management knowledge (S=5.98, p<.001 and S=2.76, p=.006, respectively). The web-based group had statistically significantly higher values for cost management knowledge (S=4,461.50, p<.001) than the mobile group. Conclusion: The cost management education program showed improvement in knowledge in both the web-based and mobile-based groups; however, the web-based approach was more effective for nurses. A cost management education program which can be implemented effectively across all range of nurses is recommended.

• Journal of Korean Academy of Nursing
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• v.49 no.5
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• pp.586-600
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• 2019

Purpose: This study aimed to develop a web-based cost management program for visiting nursing centers (CMP-VNC), using time-driven activity-based costing (TD-ABC), and to analyze effects of the program. Methods: The CMP-VNC was developed using the combined prototyping approach and system developing life cycle method following four stages: need analysis with comprehensive literature reviews and focus group interviews, design and development of program algorithm, evaluation of the developed program validity using experts and users group, and application and effects analysis. The non-equivalent control group pretest-posttest design was used to analyze the effects of the program. The program demonstration was conducted for four weeks with 60 visiting nurses in 35 visiting centers. Results: The web-based program was developed. It has five interfaces with basic and special functions using TD-ABC, namely, input, visiting nursing activity, visiting nursing activity cost, cost efficiency, and cost calculation report. The experimental group showed significantly higher cost perception and cost confidence than control group. Conclusion: We found that the CMP-VNC can be an effective tool to increase visiting nurses' competency of costing and enhance efficiencies of visiting nursing centers.

• Plant Journal
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• v.5 no.1
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• pp.40-44
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• 2009

This study presents an operational technique to maximize the profit of a cogeneration power plant under cost-based pool power market. In benefit side energy sale profit, heat sale profit, and supplementary fund profit for electric power industry are included and the changeable cost was considered in cost side. The profit of a cogeneration power plant is varied enormously by the operation conditions, and constraint conditions. The result of this case study can be used as a reference to a cogeneration power plant under the same power trading system.