• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4B
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• pp.191-199
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• 2007

Mobile node has to register its current location to Home Agent when it moves to another network while away from home. However, the registration procedure cannot be completed successfully when Home Agent is protected by the VPN gateway which guards MN's home network and discards the unauthorized packets incoming from outside as a lack of security association(SA) between the Care-of address and security policy of the home network so that the binding registration message without SA is discarded smoothly by the VPN gateway. This paper presents the authentication and key exchange scheme using the AAA infrastructure for a user in Internet to access the home network behind the VPN gateway. By defining the role of authentication and tunnel processing for each agent or relay entity, this paper presents the procedure to register the current location to its Home Agent with secure manner. Performance result shows cost improvement up to 40% comparing with existing scheme in terms of the packet loss cost, the property of mobility and traffic.

• Korean Journal of Construction Engineering and Management
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• v.8 no.3
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• pp.106-115
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• 2007

The size and length of road tunnels have been gradually expanded as industry developed. Consequently, the risk has been increased. The decision making process for ventilation system for road tunnels involves a large amount of information on economic feasibility, construction methods, and safety etc. In situation where systematically structured decision making process is unavailable, almost decisions about ventilation systems are made based on engineers' private knowledge and experiences. Procedure and criteria to choose the best optimized ventilation system among many alternatives are proposed, breaking away from the economic dependency-oriented decision making. This paper presents a Multi-Attribute Utility Theory and AHP based function with which planners can calculate overall utility of each alternative. It is anticipated that the effective use of the proposed methodology for decision making on ventilation systems ould be able to reduce the likelihood of the occurrence of potential safety risks as well as increase the overall ventilation performance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.465-473
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• 2013

In this Study, the performance of precast PSC slabs with fire resistance panel for fire resistance of the tunnel system was evaluated by experimentally. The fire test was performed in fire resistance (electric) furnace according to RABT(Richtlinien fur die Ausstatung und den Betrieb von stra${\beta}$entunneln) time heating temperature curve. The test results showed that the measured temperatures at the t=0 mm depth of PSC slab with precast fire resistance panel during a fire was maximum temperature $367^{\circ}C$, lower than $380^{\circ}C$ (ITA 2004), when damage occurs. Also, at the t=25 mm, the maximum temperature was $239^{\circ}C$, which was lower than the damage temperature of rebar, $250^{\circ}C$. From the results, the use of precast fire resistance panel (t=25 mm) improves fire resistance of PSC structures.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.537-540
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• 2010

An Enhanced Huels Type Plasma Torch that generates over $5000^{\circ}C$ plasma arc flow is the core equipment of arc-jet wind tunnel. It is applied to the high-tech areas such as a new materials development and eco-friendly industry. Although the Enhanced Huels Type Plasma Torch produce uniform flow of high purity, its complicated structure and operating condition makes the commercialization of it to be difficult. The 400kW arc-jet generator using the enhanced Huels type plasma torch was tested. The result of this study showed that the torch was operated in the range of 280~320 A and 250~1350 V.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.322-326
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• 2003

Dae-gu subway accident raise whole points in connection with safety facilities and operating of national urban transit system like rolling stocks, facilities, management of human. Rolling stock is made every effort for improvement of performance, guarantee of comfortableness, insurance of economical efficiency. But Security like safety of fire is not thoroughgoing enough. Especially, interior material has used although it is not prove its degree of safety. it is a main cause of Dae-gu subway accident. Safety regulation of urban transit vehicle that legislate for security in March 2000 does not applied manufacturing vehicles before in 2000. It has be prescribed in the regulations that incombustibles must be used. But detailed test standard related with incombustibles is not prescribe. Thus that regulation be required reinforcement of detailed test standard. Main cause of Dae-Gu subway accident is a fire in vehicle. However, many defects are found in infrastructure and operating vehicle of urban transit, such as inexperienced disposal of driver and CCC in early stage of the fire accident, unskilled opening and closing doors, insufficient escape facilities and safety facilities of a station house and tunnel, and incomplete communication system between vehicle and CTC, extraordinary step. Thus the aims of this study are prevention of urban transit accident, improvement plan of safety driving, and proposal of quick action plan through analysis of total faculty of vehicle.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.3.1-3.8
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• 2018

Background: In this research article, we evaluate the use of sub-periosteal tunneling (tunnel technique) combined with alloplastic in situ hardening biphasic calcium phosphate (BCP, a compound of β-tricalcium phosphate and hydroxyapatite) bone graft for lateral augmentation of a deficient alveolar ridge. Methods: A total of 9 patients with deficient mandibular alveolar ridges were included in the present pilot study. Ten lateral ridge augmentation were carried out using the sub-periosteal tunneling technique, including a bilateral procedure in one patient. The increase in ridge width was assessed using CBCT evaluation of the ridge preoperatively and at 4 months postoperatively. Histological assessment of the quality of bone formation was also carried out with bone cores obtained at the implant placement re-entry in one patient. Results: The mean bucco-lingual ridge width increased in average from 4.17 ± 0.99 mm to 8.56 ± 1.93 mm after lateral bone augmentation with easy-graft CRYSTAL using the tunneling technique. The gain in ridge width was statistically highly significant (p = 0.0019). Histomorphometric assessment of two bone cores obtained at the time of implant placement from one patient revealed 27.6% new bone and an overall mineralized fraction of 72.3% in the grafted area 4 months after the bone grafting was carried out. Conclusions: Within the limits of this pilot study, it can be concluded that sub-periosteal tunneling technique using in situ hardening biphasic calcium phosphate is a valuable option for lateral ridge augmentation to allow implant placement in deficient alveolar ridges. Further prospective randomized clinical trials will be necessary to assess its performance in comparison to conventional ridge augmentation procedures.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.75-80
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• 2013

In this study, a forced ignition method with a plasma jet torch is studied in Mach 2 laboratory scaled wind-tunnel. The hyper-mixer is used as a mixer. For two normal injection cases, the one is collided against a wedge plate of the hyper-mixer and the other is directly injected into the cold main flow. For the first case, the hyper-mixer disperses the injected fuel, leading to the mixing enhancement. Furthermore, the fuel-air mixture is provided into the plasma hot gas, which enhances the combustion performance. However, the direct injection into the main flow method spends amount of fuel without ignition in the cold supersonic flow. In the end, for the forced combustion, it is important to supply the fuel-air mixture into the heat source.

• Wind and Structures
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• v.22 no.2
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• pp.211-234
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• 2016

Super long-span bridges provide people with great convenience, but they also bring traffic safety problems caused by strong wind owing to their high decks. In this paper, the large eddy simulation together with dynamic mesh technology in computational fluid dynamics (CFD) is used to explore the mechanism of a moving vehicle's transient aerodynamic force in crosswind, the regularity and mechanism of the vehicle's aerodynamic forces when it passes through a bridge tower's wake zone in crosswind. By comparing the calculated results and those from wind tunnel tests, the reliability of the methods used in the paper is verified on a moving vehicle's aerodynamic forces in a bridge tower's wake region. A vehicle's aerodynamic force coefficient decreases sharply when it enters into the wake region, and reaches its minimum on the leeward of the bridge tower where exists a backflow region. When a vehicle moves on the outermost lane on the windward direction and just passes through the backflow region, it will suffer from negative lateral aerodynamic force and yaw moment in the bridge tower's wake zone. And the vehicle's passing ruins the original vortex structure there, resulting in that the lateral wind on the right side of the bridge tower does not change its direction but directly impact on the vehicle's windward. So when the vehicle leaves from the backflow region, it will suffer stronger aerodynamic than that borne by the vehicle when it just enters into the region. Other cases of vehicle moving on different lane and different directions were also discussed thoroughly. The results show that the vehicle's pneumatic safety performance is evidently better than that of a vehicle on the outermost lane on the windward.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.460-475
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• 2016

The existing Proxy Mobile IPv6 suffers from a long handover latency which in turn causes significant packet loss that is unacceptable for seamless realtime services such as multimedia streaming. This paper proposes an OpenFlow-enabled proxy mobile IPv6 (OF-PMIPv6) in which the control of access gateways is centralized at an OpenFlow controller of a foreign network. The proposed OF-PMIPv6 separates the control path from the data path by performing the mobility control at the controller, whereas the data path remains direct between a mobile access gateway and a local mobility anchor in an IP tunnel form. A group of simple OpenFlow-enabled access gateways performs link-layer control and monitoring activities to support a comprehensive mobility of mobile nodes, and communicates with the controller through the standard OpenFlow protocol. The controller performs network-layer mobility control on behalf of mobile access gateways and communicates with the local mobility anchor in the Proxy Mobile IPv6 domain. Benefiting from the centralized view and information, the controller caches the authentication and configuration information and reuses it to significantly reduce the handover latency. An analytical analysis of the proposed OF-PMIPv6 reactive and proactive handover schemes shows 43% and 121% reduction in the handover latency, respectively, for highly utilized network. The results gathered from the OF-PMIPv6 testbed suggest similar performance improvements.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.137-142
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• 2013

The displacement Deep-V catamaran concept was developed in Newcastle University(UNEW) through development of the systematic Deep-V catamaran series. One of the most important Deep-V catamaran launched to date is Newcastle University's own multi-purpose research vessel, The Princess Royal. The vessel was launched in 2011 and enhanced the Deep-V catamaran concept further with the successful adoption of a novel anti-slamming bulbous bow and tunnel stern for improved efficiency. It was however identified that the vessel has substantial amount of dynamic trim that limited the visibility of the captain. The dynamic trim also increased the wave-making resistance thereby preventing the vessel from attaining its maximum speed in certain sea states. This paper therefore presents the application of devices such as Trim Tabs, Interceptors, Transom Wedges and Integrated Transom Wedges-Tabs to control the dynamic trim and improvement of fuel efficiency of the vessel. All of these energy saving devices were fitted into a model for tests in Newcastle University's Towing Tank. Model test verification confirmed that the optimum appendage was the interceptors, they produced a 5% power saving and 1.2 degree trim reduction at 15 knots, and investigations of full scale trials will be scheduled with and without application of device to compare the improvement of performance.