• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.11a
• /
• pp.46-47
• /
• 2018

High performance concrete with low water-to-cement ratio has been widely used with increased demand of high rising buildings and huge scaled structures. Additionally, for high performance concrete, various SCMs are replaced to improve its performance from fresh state to hardened state. With the drawback of increased viscosity of the concrete mixture for high performance concrete, low-viscosity typed high range water reducer is the relatively new admixture. Therefore, as a goal of the research, under using various SCMs with wide range of content, the performance of low-viscosity typed high range water reducer was evaluated. Especially, in this research, the influence of low-viscosity typed high range water reducer on rheological properties including plastic viscosity and yield stress were assessed. As a result of the research, it is expected to provide a fundamental information of low -viscosity typed high ranged water reducer on high performance concrete with various conditions of SCMs.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.10a
• /
• pp.731-736
• /
• 2011

In this study, the safety of the driving gear reducer of ESW traveling sea water screen was evaluated through seismic analysis. Mode analysis of gear reducer was performed for reliability of analysis. Seismic analysis was performed in Operating Basis Earthquake(OBE) and Safe Shutdown Earthquake(SSE), which was applied as design condition using Floor Respnse Spectrum(FRS). The maxsimum displacement of gear reducer under OBE and SSE were 0.0137 mm and 0.0241 mm, respectively. The maximum stress of gear reducer under OBE and SSE were 2.42 MPa and 4.36 MPa, respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.7
• /
• pp.599-604
• /
• 2012

In this study, the safety of the driving gear reducer of ESW(essential service water) traveling sea water screen was evaluated through seismic analysis. Mode analysis of gear reducer was performed for reliability of analysis. Seismic analysis was performed in operating basis earthquake(OBE) and safe shutdown earthquake(SSE), which were applied as design condition using floor response spectrum( FRS). The maximum strain of gear reducer under OBE and SSE were 20.4 ${\mu}$ and 33.6 ${\mu}$, respectively. The maximum stresses were 2.42 MPa under OBE condition and 4.36 MPa under SSE condition, which were smaller than the allowable strength of material.

• Journal of the Korea Institute of Building Construction
• /
• v.13 no.6
• /
• pp.594-601
• /
• 2013

One of the important problems associated with building demolition is the dust generated during the work. The only way to reduce the demolition dust is to use a dust net during water spraying. However, it is difficult to supply the necessary amount of water to remove demolition dust, thus making it difficult to apply this method on a demolition site. This work attempted to find an alternative approach to dust removal by incorporating surfactant and high range AE water reducer in the water being sprayed. Through the experiment, it was found that the addition of surfactant did not contribute to the removal of demolition dust. However, the use of high range AE water reducer showed better performance than spraying plain water, indicating that some amount of demolition dust had been adsorbed on the high range AE water reducer.

• Journal of the Korea Institute of Building Construction
• /
• v.17 no.5
• /
• pp.429-435
• /
• 2017

The aim of the research is, for normal strength range concrete mixture, to evaluate the fluidity development and robustness of the mixture depending on various water reducers. Although a usage of water reducer has been essential to make a concrete under the current conditions of worsen aggregate quality, selection of appropriate performance of water reducer is significant. Hence, in this research, regarding the normal strength range mortar, three different performance of water reducers were evaluated in aspects of securing fluidity, and robustness, rheological behaviors. Additionally, for the concrete mixture, the fluidity change was evaluated depending on unit water content for each different water reducer, and the water reducing performance with manufacturing cost was compared and analyzed. By the result of this research, it is expected to provide a case of determining appropriate kind of water reducer and to contribute on conditions of securing sufficient fluidity with stable quality and economical advantage.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.13 no.1
• /
• pp.1-6
• /
• 2017

In this paper, the flow characteristics of water in the water supply pipes of a WBC array were evaluated. We simulated the flow velocities and pressures for a standard pipe, an expansion pipe with a concentric reducer, and an expansion pipe with an eccentric reducer using computational fluid dynamics. In the case of the standard pipe, when the inlet flow velocities were 0.5 m/s and 2.0 m/s, the maximum flow velocities at the center of the WBC array were 0.54 m/s and 2.74 m/s, respectively, which were the greatest values among those of all the pipe models considered. In the case of the expansion pipe, the maximum flow velocities at the center of the WBC array were almost the same under the same conditions regardless of the type of reducer. The pressure losses in the pipe due to the concentric and eccentric reducers were found to be (165.09 ${\times}$ inlet $velocity^{1.6677}$) and (210.98 ${\times}$ inlet $velocity^{1.6478}$), respectively. The coefficient of determination at this time was greater than 0.99 and was the same for both the models. As a simulation result, it was found that in order to reduce the pressure loss when pipe with WBC array is connected with a conventional pipe, diameter of the pipe with WBC array at that section should be enlarged by one step, and then connected to the conventional pipe with a concentric reducer.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.11a
• /
• pp.115-116
• /
• 2015

Since concrete has evolved to the development of the quality and performance there currently being used civil engineering, as the most important material in the construction sector. But the discovery of alternative building materials and indiscriminate use is negligible. So that is the situation facing the shortage of natural aggregate. Accordingly, this study reviewed the mechanical properties by replacing the aggregate through the mud flat of eco-friendly materials and analyze the usability by adding a high-performance water reducer for promoting workability.

• Journal of Microbiology
• /
• v.37 no.4
• /
• pp.206-212
• /
• 1999

In order to isolate a Fe(III)-reducer from the natural environment, soil samples were collected from various patty fields and enriched with ferric citrate as a source of Fe(III) under anaerobic condition. Since the enrichment culture was serially performed, the Fe(III)-reduction activity was serially diluted and cultivated on an agar plate containing lactate and ferric citrate in an anaerobic glove box. A Gram negative, motile, rod-shaped and facultative anaerobic Fe(III)-reducer was isolated based on its highest Fe(III)-reduction activity, Bacterial growth was coupled with oxidation of lactate to Fe(III)-reduction, but the isolate fermented pyruvate without Fe(III), The isolate reduced an insoluble ferric iron (FeOOH) as well as a soluble ferric iron (ferric citrate). Using the BBL crystal enteric/non-fermentor identification kit and 16S rDNA sequence analysis, the isolate was identified as Shewanella putrefaciens IR-1.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.11
• /
• pp.1399-1406
• /
• 2011

The reducer of the mixer is one of the main parts of the processor used for water and wastewater treatment. In this study, an advanced reducer with a drywell structure was developed in order to prevent oil leakage during operation in the field. During the development of the advanced reducer prototype, a mockup, a metal mold, and a cast were made using CAD and a CNC machine. The structural safety of the reducer prototype's lower housing (drywell structure) was checked using the ALGOR commercial FEM analysis code, which yielded a von Mises stress of about 123 N/mm2, which is below the yield stress of 250 N/$mm^2$, and a natural frequency of about 650-700 Hz. In addition, the torque transmission efficiency for the advanced prototype was 95.87%, which is about 8% more than that found in a previous study, 88.45%, and the sound level was below 75 dB. Furthermore, no oil leakage or abnormal sound or vibration occurred. Therefore, an optimally designed advanced reducer prototype has been successfully developed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.2
• /
• pp.1541-1548
• /
• 2015

In this study, strengthening methods of floor surface finishing mortar are investigated to prevent the cracks using crack inhibitor agents, water reducer agent and resin. As a results, The number of crack and compressive strength of the specimen containing water reducer agent or resin had more effective than other specimens containing inhibitor agents at 7 days. And the highest compressive strength specimen showed the relatively no crack, but the lowest compressive strength specimen showed a lot of crack. Therefore the relationship between the crack growth and the compressive strength had proportional connection. A base on the mock-up test, long-term monitoring of the on-site applied to mixing design type3 showed the few cracks.