• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.830-837
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• 2011

A turbine control system which has been operated for years in a nuclear power plant was retrofitted with a newly developed digital control system. After completion of the retrofit, turbine valve tests were performed to ensure the integrity of each valve's control function. The sequence of each valve test is composed of a closing process and a reopening process. To minimize megawatt variation which normally occurs during the test sequence, we employed a kind of compensator algorithm in the new digital control system which also have been used in the old system. There were difficulties finding optimal parameter settings for our new compensator algorithm because the power plant didn't allow us to perform necessary tuning procedures while the turbine is on load operation. Therefore an alternative measure for the compensator tuning which is independent of the turbine actual operation had to be implemented. So, a process model for the test was required to overcome this situation. We analyzed the operation data of the test and implemented the process model by use of input and output variable relations. Also we verified the process model by use of another condition's operating data. The result shows that the output of model is similar to the actual operation data.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.4
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• pp.431-436
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• 2023

In order to provide continuous Korea Augmentation Satellite System (KASS) services, the operation organization should continuously and systematically perform operations, maintenance, and technical activities. All subsystems of KASS, all Line Replacement Units (LRUs), and Software Replacement Units (SWRUs) should be operated and maintained continuously. In order to effectively manage these activities, it is necessary to develop an Operation Management Tool (OMT). For this purpose, operation management, operation organization, and operation activities were defined. The defined requirements were divided into general, function, interface, and database for OMT development, and functions and decision-making procedures consisting of site/asset/trouble/work order/schedule management were designed. The OMT developed by reflecting the site and asset information as well as the design content met predefined requirements. The OMT will be actively used in actual KASS operation and will evolve by continuously reflecting the additional requirements of operators. Through this tool, KASS will support continuous service provision.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.209-214
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• 2007

This study is concerned with working hardening of bending operation on hydroforming parts. Generally, hydroforming parts having the complicated shape of the automobile, require a 3-dimentional bending operation. This operation involves several variations in the tube which are the thickness, the mechanical characteristics, the hardness, the circumference etc., on original tube. So, we study those variations and the affect on the hydroforming operation and hydroforming parts. We used two methods, one of which was computer simulation and the other the actual test in the plant.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.487-498
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• 2022

This study aims to determine the importance of each factor considered when operating a rotorcraft in a city. After identifying factors that could affect urban air mobility, we reviewed the influencing factors by applying an analytic hierarchy process (AHP). Level 1 classifies the essential factors of the urban operation of rotorcraft in nominal and off-nominal situations. The factors corresponding to the characteristics of each were composed of lower levels, such as Levels 2 and 3. Using this, the importance of influencing factors was analyzed and the most important factors were determined. The most influential factors of the urban operation of rotorcraft included engine failure, fire situations, and vehicle safety. Accordingly, an environment that can guarantee safe operation by considering the most influential factors in advance in an actual operation stage must be constructed.

• KIEE International Transactions on Power Engineering
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• v.3A no.3
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• pp.148-154
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• 2003

This paper describes the development of KEPCO's 80MVA UPFC electromagnetic transient model and the analysis of its performance in the actual Korean power system. KEPCO's 80MVA UPFC is currently undergoing installation and will be ready for commercial operation from the year 2003. In order to apply a new FACTS device such as the UPFC to the actual power system, the utility needs, in advance, both load flow stability studies and transient studies. Therefore, KEPRI, the research institute of KEPCO, developed a detailed transient analysis model that is based on the actual UPFC S/W algorithm and H/W specifications. This simulation model is implemented by an EMTDC/PSCAD package. The results of the simulation show the effectiveness of UPFC operation in the KEPCO power system.

• Journal of the Korean housing association
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• v.26 no.2
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• pp.29-38
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• 2015

The purpose of this study is to understand the actual condition of Bogumjari Housing Complex residents' management consciousness and to provide suggestions on ways to induce residents' volunteer participation and practice of the apartment management. This study was performed on Bogumjari Housing Complex which was occupied in 2012 and the similar-sized apartment complex of the private condominium to compare and analyze their actual condition of management and consciousness of their residents. The results of the analysis could be summarized as follows: 1) In terms of management of operation, there is no distinct difference. In terms of maintenance management, Bogumjari Housing Complex has difficulty in maintenance because of lack of management manpower. Also, the apartment complex of the private condominium has higher spontaneous participation rate, which seems to be influenced by activation of various organizations. 2) In terms of the satisfaction of management process, Bogumjari Housing Complex has have higher satisfaction with promotion of the apartment Management Rules, but it has lower satisfaction with public hygiene, community facility maintenance and operation of program than that of apartment complex of the private condominium. 3) Bogumjari Housing Complex has higher maintenance and participation consciousness, drawing conclusion that Bogumjari Housing Complexs' residents have higher expectations for apartment, a keen interest and strong will.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.3
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• pp.425-431
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• 2016

Supply Capability of the generator, if the maximum demand occurs, refers to the maximum power that can be stably supplied and it is possible to maintain stable power supply to be greater than actual load. However, unexpected power demand and reduction in supply Capability due to stop of unexpected generator in operation can temporarily make a big chaos in power system. In fact, due to a lack of power supply Capability in the country, enforced emergency load adjustment to the September 15, 2011, the circulation power outage has occurred in several cities. As the result, interrupted operation of the elevator and stopped hospital medical equipment led to a great deal of trouble to people's lives, causing a social problem. At that time, it was found that a failed frequency control because of smaller actual supply Capability than that of predicted. The difference was about 1,170 MW with Gas turbine power plant. By accurately calculating the generator supply capability, we can not only grasp the power reserve rate, but also correspond to the time of power supply instability.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.53-59
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• 2017

The information on the actual voltages and actual currents of the motor is required for the sensorless control of a permanent magnet synchronous motor without rotor position sensors. In the model-based rotor position estimator of a PM synchronous motor, the reference voltages, which are the outputs of the current controller, are commonly used. The reference voltages in over-modulation regions for high-speed operation differ from the actual voltages applied to the motor. Consequently, the estimated rotor position and rotor speed may fail to track the real rotor position and real rotor speed. In this paper, the sensorless control for a PM synchronous motor in over-modulation regions for high-speed operation is proposed. The three-phase voltages applied to the motor are measured by using additional voltage detection circuits, and the performance of the rotor position estimator based on the measured three-phase voltages is validated through the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.442-450
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• 2012

Almost domestic power plants are being operated by foreign distributed control system. Many korean power plants are being operated over their lifetime so they need to be retrofitted. So we are developing the distributed control system to solve this problem by our own technique. The simulator was already made to verify the reliability of the algorithms. The unit loop function tests of all algorithms were finished in the actual distributed control system for installation of power plant and their results were satisfactory. The unit loop function tests are for each unit equipment algorithm. So the total operation tests will be made with all algorithms together in the actual distributed control system to be applied to power plant. When the verification through all tests is finished, algorithms with hardware will be scheduled to be installed and operated in the actual power plant. This research result will contribute to the safe operation of the deteriorated power plant and korean electric power supply as well as domestic technical progress. This entire processes and results for the development are written for the example of boiler feedwater master algorithm out of all algorithms in this paper.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.99-109
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• 2012

Sub-station, key equipment in electric power infrastructure, are being exposed to increasing risk of hacking. For this, soft redundancy sub-station system needs to be formulated with automatic restoration mechanism. For this it is important to assess the reliability of the applicable range of data that are used in actual system operation, as well as the methods and findings of the tests. At the same time performance of soft redundancy system and total security mechanism, which are aligned for the protection of the sub-station, need to be tested. For testing the above-mentioned, this paper presented a viable formation of a soft redundancy practical VPN system within a panel to protect the latter from hacking or cracking incidences, and conducts a test to check if the considered system actually serves the protection function in the actual operation setting, gathering evidence from the data from the testing of the actual performance of the system as well as of emergency scenario simulation operations. Because tested soft-redundancy & restorative sub-station system is expected to be widely applicable for various cases such as Smart-grid or electricity IT system, where VPN with enhanced level of security is required.