• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3878-3887
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• 2022

For the future energy-mix policy for carbon neutrality, demand for the capability of load-follow operation has emerged in nuclear power plants in order to accommodate the intermittency of renewable energy. The short-term decay heat analysis is also required to evaluate the decay heat level varied by the power level change during the load-follow operation, which is a very important parameter in terms of short-term decay heat removal during a grace time. In this study, the short-term decay heat level for 10 days after the shutdown was evaluated for both seasonal and daily load-follow cases. Additionally, the nuclide-wise contribution to the accumulated decay heat for 10 days was analyzed for further understanding of the short-term decay heat behavior. The result showed that in the seasonal case, the decay heat level was mainly determined by the power level right before the shutdown and the amount of each nuclide was varied with the power variation due to the long variation interval of 90 days. Whereas, in the daily case, the decay heat level was strongly impacted by the average power level during operation and meaningful mass variations for those nuclides were not observed due to the short variation interval of 0.5 days.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.6
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• pp.15-24
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• 2005

The normalization on the characteristics of water level change at the upstream gauging station was attempted according to the operation of drainage sluice gate of the Geumgang estuary dam. The characteristics were normalized by the analysis of water level change and by the linear-regression of the water level data measured at the inner station of Geumgang estuary dam and upstream gauging station. The results of normalization may be referred to the management of Geumgang estuary lake, the operation of pumping and drainage stations in the shore of the lake. The mean response time of water level change on Ibpo, Ganggyeong and Gyuam water level station were 39,81 and 160 minutes, when sluice gate was opened respectively. The mean velocity of surface wave, the mean displacement of water level change, the mean time of water level change and the mean rate of water level change varied largely depending on the location of gauging station and the characteristics of stream section of the water level gauging station.

• Nuclear Engineering and Technology
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• v.35 no.4
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• pp.261-273
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• 2003

The characteristics of the recirculation operation of LMR which are different from the conventional plants such as PWR and fossil fuel plants were investigated using a computer code TSGS developed in this study. For simulating the transient behavior of the steam generation system, a water level control algorithm utilizing digital control hardware features was introduced. By investigation, the function of the recirculation operation was defined, the major features of the operation were found. Also good performance of the level control algorithm was confirmed.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.3
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• pp.64-69
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• 2001

Energy recovery in the regenerative region is very important when SRM is used in traction drive, This is to reduce en-ergy loss during mechanical braking and/or to have a high efficiency drive during braking To control excitation voltage in motor operation and regenerative voltage in the generator operation in the SRM multi-level voltage control is effective The paper sug-gests multi-level inverter which is useful for motoring and regenerative operation in SRM

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.10
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• pp.693-700
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• 2000

A direct torque control algorithm for 3-level inverter-fed induction motors is presented. Conventional voltage selection methods provoke some problems such as stator flux drooping phenomenon and undersirable torque control appeared especially at the low speed operation. To overcome these problems, a proposed method uses intermediate voltage vectors, which are inherently generated in 3-level inverters. In the proposed algorithm, both subdivision of the basic switching sectors and applications of tntermediated voltages improve the low speed operation characteristics. This algorithm basically considers applications in which direct torque controlled induction motors are fed by 3-level inverters with low switching frequency around 500Hz. An adaptive observer is also employed to bring better responses at the low speed operation, by estimating some state-variables, motor speed and motor parameters which take a deep effect on the performance of the low speed operation. Simulation and experiment results verify effectiveness of the proposed algorithm.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.37-43
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• 2014

The ground station which operates the LEO satellite performs monitoring state of health of the satellite, sending the commands for the imaging mission of receiving the images during about 10 minutes of contact time. To finish the planned procedure in limited contact time, specific level of autonomy is applied in the satellite and the ground system. For example, the attitude and orbit control logic has high level of autonomy because it must be operated alone for long period without operator intervention. On the other hand, the fault management logic has relatively low level of autonomy because of that failure detection and safing operation are performed on-board, whereas failure identification and recovery are on-ground operation. The level of autonomy of the satellite affects also the ground operation. The command set for mission operation is generated by ground system. If the satellite has higher level of autonomy, some of operation currently done on-ground can be performed on-board, so the ground operation can be simplified. In this paper, we discuss the level of autonomy and propose a concept for improving the level of autonomy of an LEO satellite.

• Journal of the Korean Operations Research and Management Science Society
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• v.41 no.2
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• pp.67-80
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• 2016

Under a rapidly changing environment, firms have attempted to co-operate with organizations that possess high technologies to improve their technical capabilities. Most countries have worked towards developing a suitable strategy for international technology co-operation based on the diagnostic results of their technological capabilities and indices. These diagnostic results indicate the level and degree of international technology co-operation that have been developed in academia. However, identifying the overall conditions of international technology co-operation based on existing indices is a difficult task. Hence, to address this problem, indices that can measure diverse perspectives of core technology co-operation activities need to be developed. This research aims to develop a framework for identifying the current state of international technology co-operation in diverse perspectives at the national level. We develop indices based on relevant literature and formulate an analytical framework for international technology co-operation in diverse perspectives using DEA analysis. The results are expected to contribute to effective technology planning at the national level by diagnosing capabilities for international technology co-operation from diverse perspectives.

• Journal of Chest Surgery
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• v.15 no.4
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• pp.460-466
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• 1982

A analysis of CPK & LDH Isoenzyme was done on the consecutive patients undergoing thoracic operations from July 1982 to October 1982 in the Department of Thoracic and Cardiovascular Surgery, Capital Armed Forces General Hospital. Eighteen patients were analysed by three groups, such as open heart surgery [group A], major thoracic operation [group B] , minor thoracic operation group [group C]. In all patients serial determination of total level and Isoenzyme of CPK, LDH wad done on preoperative operative and up to 8th post-operative day, The results obtained are as follows. 1. The average value of serum CPK before the operation was 61 IU/L. The value of serum CPK was increased following the operation mainly MM portion and reached to the maximal level of 536107 IU/L in A group 1200191 IU/L in B group, 306150 IU/L in C group on the first postoperative day. The enzyme activity was gradually decreased thereafter and returned to the normal range on the 3rd or 4th day after the operation. 2. The average value of serum LDH before the operation was found to be 83 IU/L. The value was increased during the operation and reached to the maximal level of 481108 IU/L in group A, 14827 I U/L in group B, 10035 IU/L in group C on the second day after the operation. The enzyme activity was gradually decreased thereafter and returned to the normal range on the seventh day after the operation. The enzyme activity was dependent to the duration of operation, severity of muscle damage, type of thoracotomy, effect of extracorporeal circulation, state of disease.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.10
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• pp.1012-1017
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• 2007

Rain data and water-level data are importantly used for dam operation at flood period. Because dams are directly controlled by the water-level data, the characteristic of the water-level gauges is necessary to be managed. Thus, we developed the standard test facility and method for testing the water-level gauges which are a float type, a supersonic type and a radar type. And we calculated the uncertainty of the standard test facility to maintain the accuracy of water-level gauges. Through development of this facility, we could obtain the characteristics and the calibration factor of the water-level gauges. And, this study showed that the standard test facility can be widely used for dam operation and basin management.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.341-343
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• 2012

This study introduces a method for computation of process and operation gap in the specific construction operation(i.e., RC frame construction applying a block-grouping scheme) using CYCLONE-based simulation modeling and analysis technique. Since uncertainty of construction environment exists, a thoughtful production planning is required to effectively deal with a risk resulting in schedule delay in advance. This study presents the concepts of a time delay occurred in a process level and operation level in a operation model, and a method of measuring gap-times in each level while the simulation progresses. It helps a site manager to decide how many segmentation in a construction block is suitable for eliminating unproductive time-delays under the constrained resources (e.g., laborer, equipment). A case study presents a network model representing a three segmented RC frame work, and result obtained from the simulation experiment.