• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.70.2-70.2
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• 2000

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.05a
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• pp.59-59
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• 1999

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.140-141
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• 1999

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.443-444
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• 2010

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.171-171
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• 2002

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.245-256
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• 2008

The steel rib, one of the main support of tunnel, plays a very important role to stabilize tunnel excavation surface until shotcrete or rockbolt starts to perform a supporting function. In general, a steel rib at the horizontal funnel is being installed in the direction of gravity which is known favorable in terms of constructability and stability. However, as the direction of principal stress at the inclined tunnel wall is different from that of gravity, the optimum direction of steel rib could be different from that at the horizontal tunnel. In this study, a numerical method was used to analyze the direction of force that would develope displacement at the inclined tunnel surface, and that direction could be the optimum direction of steel rib. The support efficiency of steel rib could be maximized when the steel rib was installed to resist the displacement of the tunnel. Three directions which were recommended for the inclined tunnels in the Korea Tunnel Design Standard were used for the numerical models of steel rib direction. In conclusion, the results show that all displacement angle of the models are almost perpendicular to the tunnel surface regardless of face angle. So if the steel rib would be installed perpendicular to the inclined tunnel surface, the support efficiency of steel rib could be maximized.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.417-426
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• 2015

The representative design elements of the road geometric structure are longitudinal slope, horizontal curve radius, super elevation, and transition curve. According to the function of a road, the design standards of these elements is applied by diverse combinations of them. This study divided expressway into homogeneous segments based on longitudinal slope and horizontal curve radius. And then, data required for analysis were matched to each segment, and the safety performance function was built by using the established data. crash modification factors which can explain traffic accident exposure rate were calculated. When the threshold value of horizontal curve radius R=1,000 m was set to 1.0, the crash modification factors at R=300 m was calculated as 1.33, which means that the accident exposure rate is increased by 33%. When the threshold value of the longitudinal slope 0% was set to 1.0, the crash modification factors demonstrated that the accident exposure rate decreases on the upward slope and the accident exposure rate increases on the downward slope. The results of this study can be used as basic information in the design of expressway geometries during the improvement or the construction of expressways.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.2
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• pp.107-119
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• 2018

The slope monitoring systems which have been operating at home and abroad were investigated and then the real-time monitoring management system for evacuating inhabitants based on Web-EOC(Emergency Operating Center) was constructed. We tried to analyze realistically and precisely the situation by changing from the existing field-centered management to sensor-centered management that measures coordinates and provides in real-time data of measuring/monitoring sensors installed at a field site and developing related viewer programs. In addition, the 3D based monitoring management system, which has alarm functions in case of emergency and provides information about the evacuation place, was constructed on the base that is able to expand to nationwide fields by using Vworld 3D map. Ten steep slope monitoring sites were registered on Web-EOC slope monitoring management system constructed in the research and then application instances were suggested.

• Korean Journal of Metals and Materials
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• v.47 no.1
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• pp.13-20
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• 2009

This work presents functionally graded coatings (FGC) of hydroxyapatite (HA) and metallic powders on Ti-6Al-4V implants using plasma spray coating method. HA has been the most frequently used coating material due to its excellent compatibility with human bones. However, because of the abrupt changes in thermomechanical properties between HA and the metallic implant across an interface, and residual stress induced on cooling from coating temperture to room temperature, debonding at the interface occurs in use sometimes. In this work, FGC of HA and Ti or Ti-alloy powders is made to mitigate the abrupt property changes at the interface and the effect of FGC on residual stress release is investigated by evaluating the mechanical bond strength between the implant and the HA coating layers. Thermal annealing is done after coating in order to crystallize the HA coating layer which tends to have amorphous structure during thermal spray coating. The effects of types and compositional ratio of metallic powders in FGC and annealing conditions on the bond strength are also evaluated by strength tests and the microstructure analysis of coating layers and interfaces. Finally, biocompatibility of the coating layers are tested under ISO 10993-5.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.193-196
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• 2008

Z. Cao had proposed NFRM(new fuzzy reasoning method) which infers in detail using relation matrix. In spite of the small inference rules, it shows good performance than mamdani's fuzzy inference method. In this paper, we propose 2. Cao's fuzzy inference method using learning ability witch is used a gradient descent method in order to improve the performances. Because it is difficult to determine the relation matrix elements by trial and error method which is needed many hours and effort. Simulation results are applied linear and nonlinear system show that the proposed inference method has good performances.