• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.405-412
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• 2008

This study was aimed to investigate whether an oxygen inhibition layer (OIL) is essential for the interfacial bonding between resin composite layers or not. A composite (Z-250, 3M ESPE) was filled in two layers using two aluminum plate molds with a hole of 3.7 mm diameter. The surface of first layer of cured composite was prepared by one of five methods as followings, thereafter second layer of composite was filled and cured: Group 1 - OIL is allowed to remain on the surface of cured composite; Group 2 - OIL was removed by rubbing with acetone-soaked cotton; Group 3 - formation of the OIL was inhibited using a Mylar strip; Group 4 - OIL was covered with glycerin and light-cured; Group 5 (control) - composite was bulk-filled in a layer. The interfacial shear bond strength between two layers was tested and the fracture modes were observed. To investigate the propagation of polymerization reaction from active area having a photo-initiator to inactive area without the initiator, a flowable composite (Aelite Flow) or an adhesive resin (Adhesive of ScotchBond Multipurpose) was placed over an experimental composite (Exp_Com) which does not include a photoinitiator and light-cured. After sectioning the specimen, the cured thickness of the Exp_Com was measured. The bond strength of group 2, 3 and 4 did not show statistically significant difference with group 1. Groups 3 and 4 were not statistically significant different with control group 5. The cured thicknesses of Exp_Com under the flowable resin and adhesive resin were 20.95 (0.90) urn and 42.13 (2.09), respectively.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.3
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• pp.135-141
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• 2005

The static friction coefficients of 4 samples against each different temperatures were similar values. Compared against RT, at $80^{\circ}C$ the static friction coefficients decreased from 0.130 to 0.116 that was equal from 88% to 90% of the static friction coefficients respectively. Otherwise the dynamic friction coefficients compared against RT, decreased from 0.138 to 0.088 which was from 71% to 77.5% respectively at $80^{\circ}C$. The noise characteristics were judged by s/d value. And when the s/d value was limited less than 0.8, noise concerns were released. At 3000 engaging cycles the static friction and the dynamic friction coefficient were 0.137 and 0.073 respectively. When plate pressure rose up to $195kg_f/cm^2$, the static friction coefficient decreased from 0.137 to 0.125 but this decreasing could be considered as stable. When speed rose up to 2200rpm, the static friction coefficient decrease from 0.14 to 0.13 but this decreasing could be considered as stable. At 3000 engaging cycles the amount of worn out was 0.04 : the thickness of disc was decrease from 4.72mm to 4.68mm. But regarding the normal operation condition, further more worn-out could not be expected. Therefore concerning worn-out, the basic oil could be considered as appropriate.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.131-136
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• 2011

In commercial vehicle, sub-frame which equipped in main frame supporting dump deck and oil tanker. This is the main structure for all equipment which including joint function. Sub-frame is made by welding process, this susceptible to deform and crack by its longitudinal size. Also various kind of sub-frame make it difficult to standardization in manufacturing process and exclusive jig is not adapted yet. Frame size is over 6~8m and weight is more than 300kg this make re-work more difficult. If manufacturing company made precise sub-frame, this is not only convenient for customers but also save the company money by reducing the working time. In this study manufacture the sub-frame be suitable for its main function and develop exclusive welding jig for obtain checking fixture function as well.

• Journal of Korea Port Economic Association
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• v.34 no.4
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• pp.39-52
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• 2018

The Seosan-Daesan Port is a representative trade port in Chungnam, and has the sixth largest total cargo throughput and the third largest oil cargo throughput in Korea. However, research on this port's development is lacking relative to that for Busan Port, Incheon Port, and Gwangyang Port, and no study exists that suggests the direction of the development strategy for Seosan-Daesan Port. This study discusses the future role of Seosan-Daesan Port in preparation for a rapidly changing future and the development strategy that should be established. Using the AHP, a development strategy is provided for Seosan-Daesan Port from short/mid-term and long-term viewpoints for three aspects: operation activation, infrastructure construction, and policy support. Operation activation is chosen as the most significant factor from a short/mid-term viewpoint, whereas infrastructure construction is recognized as important from a long-term viewpoint. Specifically, from a short/mid-term viewpoint, sustainable container cargo attraction, multipurpose dock construction, management pier construction, and opening of international passenger ferry lines are important factors while from the long-term viewpoint, hinterland construction, petrochemical industry cluster construction, automobile industry cluster construction, and management improvement system are important. Establishing action plans for each strategy and a cooperative network for sharing goals and strengthening cooperation is necessary.