• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.45-51
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• 1982

An endodontically treated tooth is likely to be brittle than a vital tooth. Internal structure of the tooth has been weakened due to a significant removal of dentin by coronal access, canal preparation. There are many controversies concerning with various methods of reinforcing an intact anterior tooth that has endodontic treatment. In this experiment, 128 extracted maxillary anterior teeth were endodontically treated, and prepared with 4 methods of restorations; Composite resin filling with zinc phosphate cement, composite resin filling without zinc phosphate cement, composite resin filling with post, and metal crown with post. An Instron testing machine was used to measure the fracture loads of the specimens. The means of the failure loads for the 4 groups were compared by F-test statistically and the failure modes were observed. The results were as follows; 1. There were no statistically significant difference between the failure loads of the four methods of restoration. 2. Teeth without post were fractured in a horizontal or oblique plane through upper or middle third of the root. 3. In the posted teeth, fractures were occurred around the post. 4. In the metal crowned teeth with post, the fracture were occurred around the post or coronal area.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1-13
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• 2010

Numerous landslides had occurred in Kangwondo in July 2006 and several restoration works had been done. A-day-accumulative rainfalls from July 12 to July 13 and July 15 to July 16 were 176mm and 202mm respectively. Disaster sites at which slope failures were studied to main causes of slope failures by investigating characteristics of rainfall, geological formation, topography and ground surface exploration around the boundary of landslides. In this study, a series of slope restoration work process is presented for reference which about the landsliding area in Han-Gye-Ryeong to O-Saek in Kwangwon-do where one of the most severe damaged area in 2006. The slope restoration work process includes site investigation, analysis on affected factor, restoration or reinforcing method design, construction procedure and recent status of that area. Also several considering points are suggested while design and construction for the reference at the other restoration works.

• ETRI Journal
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• v.32 no.2
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• pp.241-247
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• 2010

We propose and experimentally demonstrate a service-aware optical transport system. The proposed service-aware optical transport system makes a flow based on service type and priority of traffic. The generated flow is mapped to a corresponding sub-${\lambda}$ for transport over an optical network. Using sub-${\lambda}$ provided by the centralized control plane, we could effectively provide quality-of-service guaranteed Ethernet service and best-effort service simultaneously in a single link. The committed information rate (CIR) traffic and best-effort traffic are assigned to different sub-${\lambda}s$. The bandwidth of the CIR traffic is guaranteed without being affected by violation traffic because the bandwidth is managed per each sub-${\lambda}$. The failure detection time and restoration time from a link failure is measured to be about 60 ${\mu}s$ and 22 ms, respectively, in the ring network. The measured restoration time is much smaller than the 50 ms industry requirement for real-time services. The fast restoration time allows the proposed service-aware optical transport system to offer high availability and reliability which is a requirement for transport networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1421-1425
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• 1999

A restoration scheme is presented when a failure occurs at nodes or links on the ATM network. Each node on the network contains the same topology information for resources on the network by Exchanging NSE(Network State Element) which has the network state information through RCC(Routing Control Channel). We also propose a new establishing algorithm that set up a new alternate path reflecting the state of the network changed dynamically at the source node. In the result of applying our scheme, the rates of restoration can be improved and the number of messages decreased so that fast recovering could be possible by reducing traffics on the network by lowering the rates of the call-setup failure at the stage of CAC(Connection Admission Control).

• Management Science and Financial Engineering
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• v.9 no.1
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• pp.29-49
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• 2003

This paper develops channel reallocation methodologies for survival transmission networks, Any failure on a high-speed telecommunication network needs to be restored rapidly and a channel real-location methodology has an important role for the fast restoration. This paper considers the channel reallocation problems under a line restoration with distributed control, where the line restoration restores the failed channels by rerouting the channels along the two alternative routes. The objective is to determine the optimal number of rerouting channels on the alternative rerouting paths of a given transmission network, where the optimality criteria are the first, the last and the mean restoration times. For each criterion, the problem is formulated as a mixed integer programming and the optimal channel reallocation algorithm is suggested based upon the characterization of the optimal solution.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.265-269
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• 1989

Computerized to techniques have been applied to outage call processing system for rapid restoration of power to customers. This paper presents computer aided outage call processing system called '123' system, which has been in operation since 1987. And, also describes its origins, design conception to be considered and its operation effects. From a positive point of view, it shows the functions needs to be added and some problems to be improved. Additionally, it describes the integrated system which has functions of detecting distribution failure, locating failure position by logical computer processing, and although ADS (Automatic Distribution System) has yet to be built up, the primary purpose of the system is to improve service to the customer by means of rapid restoration of electricity outage.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1620-1622
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• 1998

The failure occurs in the system of the underground transmission line, the time of restoration is very long, the damage from stopping power supply is very serious and the cost of restoration is very great. because of these problems, the system and equipment must be protected from every electrical failure by installing protection unit. This study is summarized and compared the effects of configuration method of cable protection device with respect to surges in EHV (Extra High Voltage) underground transmission system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.6
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• pp.1158-1168
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• 1994

The paper proposes a distributed control self-healing algorithm for a line failure to improve the restoration time. This proposed self-healing algorithm acquired the fast restoration time by reducing the number of control messages and the queueing delay. And the reduction of queueing delay was attained by the ASC_NULL(Available Spare Channel_NULL) message which informs neighbor nodes that a source node has no available spare channel to reduce the waste of time during the rerouting. It is difficult for this proposed self-healing algorithm to be compared with other self-healing algorithms, because each self-healing algorithm has different simulation conditions. So, the performance of the proposed self-healing algorithm was compared with only NETRATS(NETwork Restoration Algorithm for Telecommunication Systems). The results of the simulation showed that the proposed self-healing algorithm was better than NETRATS in the restoration time.

• Journal of Communications and Networks
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• v.16 no.5
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• pp.534-547
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• 2014

Large-scale failures resulting from natural disasters or intentional attacks are now causing serious concerns for communication network infrastructure, as the impact of large-scale network connection disruptions may cause significant costs for service providers and subscribers. In this paper, we propose a new framework for the analysis and prevention of network service disruptions in large-scale failure scenarios. We build dynamic deterministic and probabilistic models to capture the impact of regional failures as they evolve with time. A probabilistic failure model is proposed based on wave energy behaviour. Then, we develop a novel approach for preventive protection of the network in such probabilistic large-scale failure scenarios. We show that our method significantly improves uninterrupted delivery of data in the network and reduces service disruption times in large-scale regional failure scenarios.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.6
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• pp.19-28
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• 2004

Segmental Retaining Wall(SRW) has been variously applying in Civil and Architecture construction. Recently, the application of environmental element in all type's structures came to essential requirement, and the construction cases of retaining wall using reinforced soil and block are more increased than the past. But, this trend more widely was spread environmental element as landscape work for the backside of reinforced retaining wall as well as block itself. New environmental block, Greenstone Block, developed to apply of this tendency. The retaining wall system using Greenstone can be environmental constructing at both block itself and backside of retaining wall. The material tests, the axial compressive strength test of block and bending test of fiber-pipe, exercised to design and construction of vertical SRW, which were satisfied NCMA standard. Through this procedure, Rewall (ver 1.0) was developed, which can be automation design of SRW including internal stability, external stability and local stability. And these can be considered setback of retaining wall, as well the examples of vertical retaining wall using block presented to satisfying the follows; strength of reinforced geotextile, height of retaining wall, surcharge, types of backfill and groundwater level etc. Many problems investigated on after or before of construction were due to local failure, insufficiency of bearing capacity and groundwater level. Especially, the local failure was many occurred to during compaction or after construction, and the cases of SRW construction is similar to the results of model test on vertical SRW.