• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1317-1326
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• 2008

This paper presents a self.levelling system for a mass, which undergoes a severe acceleration, with integrated displacement feedback control. After a general description of such a system, theoretical analysis is investigated to design an active control device. The self-levelling system can be used to reduce the "quasi-static" deflection while isolating the "dynamic" vibration. A computer simulation model of 45 kg with two air spring mounts is considered to predict the performance of the control system. Important control parameters were acquired to meet the requirement of the system. The results showed the controller can reduce the displacement of the mass to the level of about 1/5 after control. Thus the self-levelling system can be applied usefully to reduce the displacement of a mass which experiences a high g dynamics.

• Journal of Drive and Control
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• v.4 no.1
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• pp.42-49
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• 2007

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.505-508
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• 2006

Self-leveling mortar is walkable bottom mortar which can maintain the horizontality of self fluid and have the the quick-setting quality, the low-human-effort practicable material of high-quality bottom in construction. In accordance with more adhesive strength with bottom side and absorption control, Primer is used for purpose to prevent pin-hole occurrence by self leveling mortar application prior to construction. This study is composed measurement of absorption, adhesive strength. Used material is NP-40 as nonionic emulsifying agent, uses SA-210L as negative ion emulsifying agent, uses APS, SBS as ridical initiator. A result of test, in accordance with image of Primer, as low temperature and application frequency, indicates low absorption rate and adhesive strength, as solid powder and dryness time is increse, absorption rate and adhesive strength lowly shows figure.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.41-49
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• 2018

The purpose of this study is to develop a floor mortar construction technique which has high strength and inherent mechanical properties and does not cause cracks due to shrinkage after construction. It has been demonstrated that compressive strength, bending strength, flow with floor mortar, and crack reduction performance. As a result, it was confirmed that the developed floor mortar had the same or better performance comparing with the existing foreign products. The results of this experiment can be used as a validation material for high performance and high flowable mortar construction technology with excellent material performance, economical efficiency and construction ability by securing the required performance as floor mortar and selecting the optimal formulation.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.224-234
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• 2019

Waterproof layers are installed in civil engineering structures and bridge construction is commonly finished by applying a layer of regular or asphalt concrete above the waterproof layer. However, asphalt materials are susceptible to melting at high temperature due to its superior temperature sensitivity, and this causes the waterproofing material to melt due to the high temperature of the asphalt concrete, thereby increasing the defect occurrence rate due to the thickness reduction. In this study, tensile strength and elongation of hard and soft type of MMA(Methyl Methacrylate) applied to bridges were compared in accordance to standard performance criteria based on different mixture ratios. Results of comparative testing showed that hard MMA resin can display a satisfactory tensile strength, and soft MMA resin displays satisfactory elongation properties, but as the two resin types are separately used, neither types are able to satisfy the standard requirements outlined in KS F 4932. When the amount of the powder exceeds 56.25% of the total amount, voids are generated on the surface after curing and self leveling was impossible and a heterogeneous surface is formed. Furthermore, when the hard resin: soft resin: powder mixture ratio was set to 15g: 85g: 150g. the tensile strength was $1.5N/mm^2$ and the elongation percentage was 133% which satisfy the tensile performance of KS F 4932.