• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.952-960
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• 1996

In this paper, a new overload control scheme is proposed for a control system in ATM switching system. The proposed control scheme includes a counter that conunts the number of accepted calls and is decreased at cach D time interval. In overload condition of call processor, the control scheme detects over load condition when the counter value reaches a certain threshold value. Under overload condition, processor utilization is measured and the value of the D is updataed according to the difference between measured processor utilization and target utilization. A new call is accepted accepted only if the value of the counter is less than the threshold value. In overflow condition of cell traffic, accept probability of new call is reduced exponetially according to the elapsed time. The results of simulation show that the proposed overload contorl scheme maintains the target utilization very well under the various processor overload conditions and reduces the cell loss probability under the cell overflow conditions.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.73-76
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• 2002

In electrical machinery and apparatus, the most important problem is protect of machinery and apparatus in due to transient phenomena and overload on operation. Particularly by advanced technology of late, there Is demand for low cost of equipments and high percentage of use of equipments. Therefore, protection of machinery and apparatus In condition of overload is more valued considering that all efficiency increase is passed by operating all machinery and apparatus in condition of heavyload. In this paper, the suggested system is added overload interrupt system using CT in condition of overload.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.28-30
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• 2002

In electrical machinery and apparatus, the most important problem is protect of machinery and apparatus in duo to transient phenomena and overload on operation. Particularly by advanced technology of late, there is demand for low cost of equipments and high percentage of use of equipments. Therefore, protection of machinery and apparatus in condition of overload is more valued considering that all efficiency increase is passed by operating all machinery and apparatus in condition of heavyload. In this paper, the suggested system is add overload protect system using CT in condition of overload.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.209-212
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• 2002

In electrical machinery and apparatus, the most important problem is protect of machinery and apparatus in duo to transient phenomena and overload on operation. Particularly by advanced technology of late, there is demand for low cost of equipments and high percentage of use of equipments. Therefore, protection of machinery and apparatus in condition of overload is more valued considering that all efficiency increase is passed by operating all machinery and apparatus in condition of heavyload. In this paper, the suggested system is add overload protect system using CT in condition of overload.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.21-23
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• 2005

Recently, in power system, even though the needs of digital protection relay are highly increased, there are some problem in the field during apply digital protection relay. When the relay are in the fluctuated overload condition, existing algorithm calculate the trip time only with the measured current of just previous stage, and when the load current fluctuate between overload and normal condition, existing algorithm sometimes dose not make the relay trip. This thesis will study about these kinds of existing algorithm problem in digital protection relay, and will suggest the best suited algorithm for digital protection relay in fluctuated overload condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.328-332
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• 1993

Single overload tests are carried out for SS41. Specimens are used hollow type and solid type that stress condition prevail plane stress and plane strain at surface crack. According to the crack initiation and propagation period, single overload applies to three regime and overload ratios change into 1.5, 2.0. Crack retardation zones at initation range aren't different in both specimens respectively, however at propagation range come into large scale in hollow specimen. Delayed load cycles come into large scale in solid type. And the more the overload ratio increase, the larger the retardation zone increase but the magnitude doesn't exactly equal to the expected from the overload ratio.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.527-532
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• 2012

Recently, in power system, even though the needs of protective IED(Intelligent Electronic Device) is highly increased, there are some problems in the field when use the IED. When the IED is in the fluctuated overload condition, because of the existing algorithm calculate the trip time only with the measured current of just previous measuring stage, the calculated trip time is not a proper value for the overload protection at this kind of condition, and when the load current fluctuate between overload and normal condition, because of the instantaneous reset characteristic of existing algorithm the IED dose not trip. And the non linear loads using power electronic elements seem to be increased. These non linear loads require a counterplan about various harmonics incoming to electric power systems. So we will give solutions about these problems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1741-1747
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• 2010

The development of overload management systems for distribution transformers offers new opportunities for improving the reliability of distribution systems. It allows network planners to optimize the system resource utilization and investment cost. Such an improvement in the flexibility of the distribution network is only possible if the operator has more accurate knowledge of the realtime conditions of distribution transformers. In this paper, we present an improved overload decision system for distribution transformers using realtime monitoring data. Our study can be categorized into two parts: (a) improvement in the criteria for judging the overload conditions of distribution transformers and (b) development of an overload evaluation system using realtime monitoring data. In order to determine the overload criteria, overload experiments are performed on sample transformers; the results of these experiments are used to define the relationship between the transformer overload and the increase in the top-oil temperature. To verify the accuracy of the experimental results, field tests are performed using specially manufactured transformers, the loads and top-oil temperatures of which can be measured. For arriving at online overload decisions, we propose methods whereby the measured load curve can be converted into an overload characteristic curve and the overload time can be calculated for any load condition. The developed system is able to evaluate the overload for individual distribution transformers and calculate the losses using realtime monitoring data.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1079-1088
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• 2018

A line overload emergency control strategy based on the source-load synergy coefficient is proposed in this paper. First, the definition of the source-load synergy coefficient is introduced. When line overload is detected, the source-load branch synergy coefficient and source-load distribution synergy coefficient are calculated according to the real-time operation mode of the system. Second, the generator tripping and load shedding control node set is determined according to the source-load branch synergy coefficient. And then, according to the line overload condition, the control quantity of each control node is determined using the Double Fitness Particle Swarm Optimization (DFPSO), with minimum system economic loss as the objective function. Thus load shedding for the overloaded line could be realized. On this basis, in order to guarantee continuous and reliable power supply, on the condition that no new line overload is caused, some of the untripped generators are selected according to the source-load distribution synergy coefficient to increase power output. Thus power supply could be restored to some of the shedded loads, and the economic loss caused by emergency control could be minimized. Simulation tests on the IEEE 10-machine 39-bus system verify the effectiveness and feasibility of the proposed strategy.

• Journal of Industrial Technology
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• v.31 no.B
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• pp.99-105
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• 2011

Recently, smartphones have been widely used in wireless communications which caused severe data overload in cellular networks. Cellular companies consider increasing wireless data capacity in overloaded areas. Determining overloaded areas is mainly made from user reports which are currently collected by calling or simple apps by some active users experiencing overloads. Since the current reporting method is inconvenient and does not contain detail information about the overload conditions, and therefore is used by only some active users, the overloaded areas determined from the reports are not likely to be accurate. Therefore, we need a new reporting method which is convenient enough for even inactive users to willingly report the overload condition and which delivers detail information about the overloads. In this paper, we design and implement a measurement function of smartphone's WCDMA communication quality including overload condition and management system of mobile wireless communication networks about smartphones' communication quality.