• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.10
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• pp.550-555
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• 2004

Fault section isolation and service restoration are very important for function of DAS. In Japan, a progressive protection method is used for the line to ground fault section isolation and service restoration. But the progressive protection method has a drawback that the customer will experience outage time and that the rate in use of the feeder is not over 50%. This paper presents a new Service Restoration Algorithm which is for the line to ground fault section isolation and service restoration method for a ungrounded distribution system. If the proposed algorithm is used, the rate in use of the feeder can improve than before because a distribution system can change multi connection of feeder and the customer's outage time can be reduced. The proposed algorithm has been successfully tested in a distribution system.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.2
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• pp.111-117
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• 2008

This paper presents a new continuation-based quasi-steady-state(CQSS) time-domain simulation algorithm incorporating a multiplicative aggregated load model for power systems. The authors' previous paper introduced a CQSS algorithm, which has the robust convergent characteristic near the singularity point due to the application of a continuation method. The previous CQSS algorithm implemented the load restoration in power systems using the exponent-based load recovery model that is derived from the additive dynamic load model. However, the reformulated exponent-based model causes the inappropriate variation of short-term load characteristics when switching actions occur, during time-domain simulation. This paper depicts how to incorporate a multiplicative load restoration model, which does not have the problem of deforming short-term load characteristics, into the time simulation algorithm, and shows an illustrative example with a 39-bus test system.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.7
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• pp.507-517
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• 2003

A single fiber failure in mesh-based WDM networks may result in the loss of a large number of data. To remedy this problem, an efficient restoration algorithm for a single fiber failure in the mesh- based WDM network is necessary. We propose a new algorithm for restoration scheme in WDM networks and compare it with previous schemes. Path restoration and link restoration are two representative restoration schemes which deal with only a single link failure. In this paper, we propose two kinds of efficient restoration scheme. In the proposed schemes the restoration path for each link failure is not secured. The mesh network is decomposed into a number of small loops. In one algorithm, any link failure in a certain loop is regarded as the failure of the loop and the restoration lightpath is selected by detouring the failed loop. In another scheme any link failure in a certain loop is restored within the loop. We compare performance of the proposed schemes with conventional path restoration scheme and link restoration scheme. Simulation results show that CPU time in the proposed schemes decreases compared with that in path restoration scheme and link restoration scheme, although total wavelength mileage usage increases by 10% to 50%.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.229-234
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• 2021

Iris dichotoma Pall. found on Daechung Island in Korea has been designated as an endangered species. To aid in conservation efforts of this species, this study investigated its germination characteristics and seed dormancy type. Four sets of seeds were incubated at different temperatures (4/1℃, 15/6℃, 20/10℃, and 25/15℃). One set of seeds was cold stratified (4 weeks at 4/1℃). The final germination rate and mean germination time showed that the optimal germination temperature was 25/15℃. Final germination rates were ~70%, showing no significant difference among temperature treatments. However, mean germination time were significantly different among all temperature treatments except for 4/1℃. Mean germination time for seeds with temperature treatments of 15/6℃, 20/10℃, and 25/15℃ were 3.2, 2.1, and 1.5 weeks, respectively. At 25/15℃, the mean germination time was half of that at 15/6℃. Seeds of I. dichotoma had fully developed embryos at the time of dispersal. No additional growth of the embryo was observed. Cold stratification did not affect the final germination rate or the mean germination time. This study shows that seeds of I. dichotoma have no physiological or morphological dormancy, unlike other members of the Iris genus known to have seed dormancy that needs a relatively high incubation temperature (≥25/15℃) for mass propagation to occur. These results will be useful for understanding ecophysiological mechanisms related to the species' habitat. They are also useful for mass propagation of I. dichotoma for the purpose of conserving this endangered species.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.5
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• pp.53-61
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• 2004

This paper proposes two types of sub-network based on dynamic restoration schemes to improve survivability of GMPLS networks and analyzes characteristics of these two schemes. The first proposed scheme divides with a whole GMPLS network into several sub-networks, applies a mixture of both restoration and protection methods according to fault location. The other scheme divides a whole GMPLS network into primary and secondary sub-networks, applies a restoration method in each sub-network according to fault location. In our simulation, we evaluate the performances of network resource utilization, restoration success rate, and mean restoration time and conduct its comparative analysis with conventional schemes. The simulation results show that the efficiency of network resource utilization in the proposed schemes is increased as compared with conventional restoration schemes (l＋l, 1:1, 1:N) in case of single-failed link. By contrast, we found that the performances of restoration success rate and mean restoration time in case of multi-failed link is lower than conventional restoration schemes. However, the probability that multi-failed link is occurred is very low so that the problem in practical GMPLS network is negligible.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.6
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• pp.83-93
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• 2018

In Germany has a long history of ecological restoration and restoration management. At the beginning of the 1990s, the "Erfolgskontrolle" was used as an evaluation program after the restoration project and many exchanges of views took place. It is the time, in Korea, there is a need for a comprehensive evaluation program after the restoration project, as there is no evaluation method yet. At this time it may be the "Erfolgskontrolle" in Germany as a practical model for the Korean restoration management program. The purpose of this study is to identify the concept and character of the "Erfolgskontrolle" and to demonstrate the implication and potential of application, through the analysis of the implementation example of the revaluation of river revitalization. To achieve the goal was carried out theoretical and 3 exemplary revitalization research cases. And it was endeavored to deliver the German way of acting and the basic idea to Korea. For the restoration, the "precautionary principle" should be considered first, the upper legal regulation should not be violated. In order to apply "Erfolgskontrolle" in practice, the goal formulation should be clear and systematically evaluated. And through the collection of typified cases, the comprehensive and unified theory should be established, it is possible, thus the qualitative assessment of the restoration project.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1805-1811
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• 2014

After an occurrence of a fault in any distribution system, it is desired to limit the effects of the fault to smallest possible area and restore the un-faulty areas as soon as possible. Due the advancements in communication technologies, this task can be achieved in multiple efficient ways. In order to decrease the restoration time in the Smart Grid Distribution Management System (SDMS) a communication based algorithm is proposed in this paper, in which the restoration can be done during reclosing. This paper also analyzes various communication failures with power failures cases including the entire network of communication failures. Results of all these cases have been verified by doing simulations.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.7-10
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• 2004

This paper investigated the possibility of quality restoration of deteriorated concrete caused by long distance delivery using chemical admixtures such as superplasticizer. AE agent and retarding agent. According to test results, long distance delivery lead to reducing fluidity and air content markedly, while setting time accelerated. Quality restoration agent(QRA) was made by combining super- plasticizer. AE agent and retarding agent with the proportion of 1:0.0025:0.1. It was confirmed that deteriorated concrete achieved quality restoration with the level of target slump, air content and setting time without strength loss when using QRA with proper amount.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.94-105
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• 2003

OBS(Optical Burst Switching) networks which decouple the burst from its header has characteristic one-way reservation. Therefore, the fault of a fiber link may lead to the magnitude of burst loss. Since sending a header packet and using an offset time before the transmission of the corresponding burst. In this paper, we analysis a offset time based on the burst loss rate resulting from only link failure and by applying the restoration schemes in an optical burst switching networks. The simulation results in terms of the effect of a offset time is evaluated in our network model to verify that comparing the numerical analysis with simulation result. Finally, and through these results, We propose the new restoration scheme based on offset time considered Quality of Service.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.660-668
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• 2007

In order to improve the efficiency of service restoration function in the current Distribution Automation System (DAS), in this paper it is proposed a more advanced and efficient service restoration approach using Multi-Agent technique based on distributed networks. In the current DAS, communication networks or protocol structures are centralized with communications between the central station and FRTU through 1:1 connection. In order to maintain the current systems and enhance the proposed Multi-Agent based service restoration scheme, a device of communication and intelligence, named MASX, is newly developed to make a FRTU as an agent to cooperate each others. the proposed system applied in a demo system for an distribution automation system and shows 8 times reduction of restoration time in restoration of blackouts.