• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.11
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• pp.1374-1381
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• 1999

This paper describes development of a package for generator maintenance scheduling program with user-friendly interactive mode. Generator maintenance scheduling is to select desirable maintenance periods of generators in the given interval satisfying reliability or economic criteria. Window-based system for user-friendly mode and Oracle-based database system for efficient data management are established in our package. Reserve rate levelization and LOLP minimization are performed in calculation mode, which is composed of DLL programs. Many graphs and charts are illustrated for the user-analysis. Operation is carried out by day-based unit, not by week. The case study has been conducted with the data of practical KEPCO power system in 1999 and successfully demonstrated its effectiveness.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.74-84
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• 2005

In this paper, a new coexistence mechanism between IEEE 802.15.4 and IEEE 802.11, ACROS (Active Channel Reservation for coexistence), is proposed. The key idea of ACROS is to reserve the channel for IEEE 802.15.4 transmission. During the reservation, IEEE 802.11 transmissions cannot be occurred. Request-to-send/clear-to-send mechanism of IEEE 802.11 is used to reserve channel. The proposed ACROS mechanism is implemented into PC based prototype. By the experiments, the $e{\pm}ciency$ of ACROS is proved.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.790-792
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• 1996

According to increase in electric power demand, the increasing rate of peak load compared with that of base load grows larger every year. Thus this paper deals with the optimal dynamic dispatch problem due to power rate limits and spinning reserve with loss or without loss. The first is adjusting module for gradual change of generator power by Object-Oriented Programming. The latter is an efficient dispatch module for the consideration of reasonable spinning reserve requirements. The proposed algorithm has been shown efficiency in real power system with loss.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.399-405
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• 2014

For stable integration of large-scale wind farms, integration standards (Grid codes) have been proposed by the system operator. In particular, voltage control of large-scale wind farms is gradually becoming important because of the increasing size of individual wind farms. Among the various voltage control methods, Secondary Voltage Control (SVC) is a method that can control the reactive power reserve of a control area uniformly. This paper proposes hybrid SVC when a large-scale wind farm is integrated into the power grid. Using SVC, the burden of a wind turbine converter for generating reactive power can be reduced. To prove the effectiveness of the proposed strategy, a simulation study is carried out for the Jeju system. The proposed strategy can improve the voltage conditions and reactive power reserve with this hybrid SVC.

• The Korean Journal of Health Service Management
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• v.14 no.2
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• pp.15-27
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• 2020

Objectives: The purpose of this study is to compare analysis of financial performance in university hospitals. Methods: Data from 2005 to 2017 were collected from income statement, balance sheet, and annual reports in 23 university hospitals. The dependent variables are used financial performance, namely, medical profit to total assets, medical profit to medical revenue, and net profit to medical revenue. The independent variables are establishment type, hospital province, bed, open liquidity, stability, and activity. Results: From 2005 to 2007, university hospitals steadily increased medical revenues, nonmedical revenues, medical profit, net profit, and reserve fund for essential business by investing fixed assets using financial leverage. From 2015 to 2017, the debt ratio was minimized based on existing management performance. Results showed that university hospitals maintained high profitability by actively investing in medical equipment, medical environment, and facilities using reserve fund for essential business. Conclusions: Results suggest that this will be the basic data for efficient management of university hospitals.

• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.443-448
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• 1996

Sequential brain SPECT imaging has been used to assess the cerebral perfusion reserve(CPR) in cerebrovascular diseases(UD). We have realized parametric images of CPR using deadtime correction of gamma camera and normalized difference ratio. For the anatomical localization of CPR, the parametric images were registered to the contours of the cerebral regions using optimal threshold method, which showed to reflect the CPR more reliably and distinctively than the simple subtraction. We conclude that the quantitative estimation of CPR using normalized difference ratio image could be useflll for the diagnosis and prognostic assessment of CVD.

• International Journal of Reliability and Applications
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• v.4 no.1
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• pp.13-26
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• 2003

This paper presents a comparative study of a few commonly used maintenance scheduling methods for small utilities that consists solely of thermal generating plants. Two deterministic methods and a stochastic method are examined. The deterministic methods employ the leveling of reserve capacity criterion, of which one uses a heuristic rule to level the deterministic equivalent load obtained by using the product of the unit capacity and its corresponding forced outage rate. The stochastic method simulates the leveling of risk criterion by using the peak load carry capacity of available units. The results indicate that for the size and type of the maintenance scheduling problem described In this study, the stochastic method does not produce a schedule which is significantly better than the deterministic methods.

• Imaging Science in Dentistry
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• v.54 no.1
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• pp.109-113
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• 2024

A 54-year-old male patient presented for a periodic check-up at the dental clinic. A panoramic radiograph showed bilateral ossification of the stylohyoid ligament with an oval radiopacity on the right side. Cone-beam computed tomography revealed a well-defined, homogenous hyperdense entity from the lower third of the ossified stylohyoid ligament on the right side. The differential diagnosis of osteoma on the stylohyoid chain includes Eagle syndrome and benign tumors of the stylohyoid chain and adjacent structures. Osteoma rarely manifests in the neck. Even more infrequent are tumors originating from the stylohyoid chain, with only a single documented case of osteoma reported in the literature in 1993. Due to the asymptomatic status, no surgical intervention was advised, and the case would be monitored periodically. This case report describes the details of an osteoma that emerged from the stylohyoid chain, marking it as the second recorded occurrence of this highly rare condition.

• Proceedings of the Korean Society of Crop Science Conference
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• 2006.11a
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• pp.33.1-33.1
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• 2006

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2009.10a
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• pp.129-132
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• 2009