• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1141-1155
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• 2013

A number of studies have been performed to analyze climate change impacts of water resources system. In this study, a coordinated dam operation is compared with an existing operation strategy for coping with projected future runoff scenarios. GCMs (Global Circulation Models) and the LARS-WG downscaling method was used to project future climate scenarios. The water balance model called abcd was employed to estimate future runoff scenarios. The existing dam operation comes from the national dam construction guideline, which is called the "level-operation method." The alternative coordinated dam operation are constructed as a linear programming using New York City rule for refill and drawdown seasons. The results of annual total inflow in future is projected to decrease to 72.81% for Andong dam basin and 65.65% for Imha dam basin. As a result of applying future runoff scenarios into the dam operation model, the reliability of coordinated dam operation, 62.22%, is higher than the reliability of single dam operation, 46.55%. Especially, the difference gets larger as the reliability is low because of lack of water. Therefore, the coordinated operation in the Andong & Imha dams are identified as more appropriate alternative than the existing single operation to respond to water-level change caused by climate change.

• Journal of Yeungnam Medical Science
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• v.28 no.2
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• pp.124-132
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• 2011

Background: Antiplatelet agent administration is critical in managing coronary-artery disease, but there is a concern regarding operation-related bleeding and an increase in blood transfusion in such, especially when delivering combined antiplatelet agents. This study was conducted to evaluate the effect of the administration of antiplatelet agents on off-pump coronary-artery bypass surgery (OPCAB). Methods: From March 2003 to December 2009, 49 patients who had undergone OPCAB were collected retrospectively. The patients were divided into three groups according to the administration of antiplatelet agents before the OPCAB operation: 21 patients were given an aspirin agent (group 1), 19 patients were given combined agents (aspirin+clopidogrel) (group 2), and nine patients were not given any antiplatelet agent (group 3). The three groups' perioperative hematologic and coagulation profiles, including their platelet counts, hemoglobin levels, hematocrit, prothrombin times, and aPTTs (activated partial thromboplastin times), and their postoperative bleeding, related complications, transfusion requirements, and operation times, were compared. Results: The operation time in group 2 was 4.3 hours, longer than those in the two other groups, and urgent operation was significantly most frequent in group 2 (63%). The amount of blood loss and the number of patients who received blood transfusion were not different in the three groups. The perioperative hemoglobin level, hematocrit, platelet count, prothrombin time, and aPTT were also not significantly different among the three groups. Conclusion: The continuous administration of antiplatelet agents to the patients in this study did not increase their postoperative bleeding or operation-related complications. Therefore, OPCAB may well be considered even if combined antiplatelet agents are being administered.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.842-848
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• 2011

The low-floor tram is a kind of railway vehicles which is operated on the street way track. For reducing the radius of curvature of the track, the tram consists of some carbody modules, and the articulation systems connect and support these carbody modules. The kind of articulation systems would be the hinge type and the pitching type. The hinge type articulation could allow only the yawing motion of the carbody modules, and the pitching type articulation could allow the pitching and yawing motions of the carbody modules simultaneously. With these function of the articulation systems, the tram could be operated on the horizontal and vertical curvature of the track. The number of each type of articulation could be decided with the number of carbody modules, and the manufacturer would decided the position of each type of the articulation in the view of the stability of carbody modules in the operation condition.

• Journal of The Korea Institute of Healthcare Architecture
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• v.29 no.1
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• pp.43-51
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• 2023

Purpose: To accommodate the increasing number of patients during the COVID-19 pandemic, numerous portable HEPA filter units (PHUs) were installed in the general wards of existing medical facilities(EMFs) to convert them into emergency conversion facilities (ECFs). The purpose of this study was to build a dataset in preparation for emerging infectious diseases in the post-COVID-19 era by analyzing the construction and operation of ECFs. Methods: Field investigations were conducted during ECF operation periods based on the analysis of heating, ventilation, and air conditioning (HAVC) system design documents for six ECFs across Korea. Interviews were conducted with facility managers during the field investigations. Results: When constructing an ECF within an EMF, the installation status and characteristics of the existing system should be considered. Field investigations and verifications of the operation of HAVC systems must be conducted beforehand for smooth ECF operations. If heating and cooling are required with indoor air circulation type equipment in an ECF zone, the implementation of a heating and cooling method that can satisfy the comfort requirements of the occupants while minimizing cross-contamination is essential. When using PHUs that do not meet the performance standards required by medical equipment, the noise level resulting from such equipment operation must be evaluated and improved. Implications: For EMFs, various guidelines that can be referred to for the construction and operation of ECFs must be developed to prepare for emerging infectious diseases in the future.

• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.538-545
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• 2012

In this paper a novel cascaded transformer multilevel inverter is proposed. Each basic unit of the inverter includes two DC sources, single phase transformers and semiconductor switches. This inverter, which operates as symmetric and asymmetric, can output more number of voltage levels in the same number of the switching devices. Besides, the number of gate driving circuits is reduced, which leads to circuit size reduction and lower power consumption in the driving circuits. Moreover, several methods to determination of transformers turn ratio in proposed inverter are presented. Theoretical analysis, simulation results using MATLAB/SIMULINK and experimental results are provided to verify the operation of the suggested inverter.

• Transactions on Electrical and Electronic Materials
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• v.7 no.2
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• pp.87-89
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• 2006

We investigated the current limiting characteristics of flux-lock type superconducting fault current limiter(SFCL) according to inductance variation of coil 2. The flux-lock type SFCL consists of two coils. The primary coil is wound in parallel to the secondary coil through an iron core, and the secondary coil is connected to the superconducting element in series. The operation of the flux-lock type SFCL can be divided into the subtractive and the additive polarity winding operations according to the winding directions between the coil 1 and coil 2. The current limiting characteristics in two winding directions were dependent of on the ratio of the number of turns of coil I and coil 2. The fault current increased when the number of turns of coil 2 increased in the subtractive polarity winding. On the contrary, the fault current decreased under the same conditions in case of the additive polarity winding.

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.397-407
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• 2016

This study analyzed the efficiency change and the factors affecting productivity change for the six railway operation corporations that are local public enterprises; study was performed with the DEA-CCR Model and Malmquist Productivity Index, using data collected from 2010 to 2014. Since it was not feasible to collect data on the operating expenses and the number of employees of each of the lines, the efficiencies of each operation corporation were analyzed by integrating the operation corporations, and the Malmquist Productivity Index was used to investigate the trend of the periodical productivity change. Average efficiency for urban railway operation corporations was found to be higher in the case of the bigger corporations. In 2014, the Seoul Metro and the Daejeon Metropolitan Express Transit Corporations were analyzed and found to be the most efficient operation corporations. The Malmquist Productivity Index was used to determine the periodical change; the average MPI was 1.06, with a continuous increase of productivity. The analysis showed that changes of technology were generally more obvious than change of technology efficiency for all six operation corporations.

• IE interfaces
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• v.20 no.1
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• pp.21-32
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• 2007

This paper deals with the simulation model for A-Mart logistic center design and operations. In developed simulation model, receiving docks, conveyor sorter, conveyor system, shipping docks, material handling devices and manual sorting stations are considered. Three types of cargo such as transfer center cargo, distribution center cargo and supermarket cargo are considered. The simulation model and process animation are developed using the simulation package ARENA. Among various design and operation alternatives consisting of the number of workers of receiving dock, allocation of receiving docks by cargo types, conveyor sorter velocity, the number of folk-lift, the number of manual sorting operators and overall layout, the best alternatives of each subsystem are selected by simulation analysis. The major performance measures such as sorter throughput, utilization of operators at each station, receiving docks utilization and folk-lift utilization are considered for the alternative evaluation.

• The Journal of Korean Medicine
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• v.15 no.2 s.28
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• pp.198-211
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• 1994

After giuing some anti-high blood pressure medicine of boiled-compressed fluid and 5-Kinds factors(Hydralazine, Verapamil, Clonidine, Furosemide and Hydrochlorothiazide with Kangsimsan to animals in single or together. I got the following conclusion in comparing blood-pressure and pulse of circulating system with urinating operation. 1. By joint-use of Kangsimsan and Hydralazine. it was found out that the effect of blood-pressure lowering continues longer in together-use than in single. And I coule see that the number of pulse increased. 2. By joint-use of Kangsimsan and Verapamil. the blood-pressure lowering operation was kept better in together-use than in single. the number of pulse was not affected any. 3. By joint-use of Kangsimsan and Clonidine the blood-pressure lowering operation was not found out any concrete result. 4. By joint-use of Kangsimsan and Furosemide. the Remarkble effect of Urinization was recognized to be much better in joint-use than in single. 5. By joint-use of Kangsimsan and Hydrochlorothiazide. the suppressing effect of urinization was recognized to be much better in joint-use than in single. Therefore in consideration of the above study and observation. when the joint-use of Kangsimsan and the blood-pressure lowering medicine. Hydralazine and Verapamil. the period of blood-pressure lowering was kept and I can conclude that in case of joint-use of Furosemide, a kind of good urinization. the effect of urinization by Furosemide is increased, but that of Hydrochlorothiazide is disturbed.

• Nuclear Engineering and Technology
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• v.3 no.3
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• pp.148-154
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• 1971

Some formulae have been derived for the handy calculation of the formation of radioisotope when a reactor is operated regularly on a usual on-off pattern. In particular, the case of isotope production with the present operation condition of tile Korean reactor, which is in operation for 8.2 hours from Monday to Thursday and is not operated on friday and Sunday but is back in operation on Saturday only for 3.2 hours, is discussed herein with special emphasis. Should there be no secondary nuclear reaction resulting in the transformation of produced nuclide, the formula for the calculation of its activity could be derived as follows: (equation omitted) where A: activity (dps), $\Phi$： neutron flux (n cm$^{-2}$ sec$^{-1}$ ), No : number of atoms before the irradiation, $\sigma$ : activation cross section ($\textrm{cm}^2$), λ : disintegration constant of the radioactiveisotope formed (hr$^{-1}$ ), t : elapsed time of target in the reactor (hr), n : number of elasped days of target in the reactor, m : number of days from the first day of sample irradiation to Friday, s, r, q: number of weekday of Friday, Saturday and Sunday, respectively. Since the above formula consists of many invariables on the whole, the activity of each radioisotope to be produced can he easily and conveniently made available from the chart in advance which is made of the invariable terms calculated.