• Journal of the Korea Society of Computer and Information
• /
• v.27 no.10
• /
• pp.123-130
• /
• 2022

In this paper is one of the measures to prevent concrete collapse accidents at construction sites in advance. Analyzed based on accumulated Meteorological Agency data. It is a reliable model that confirms the prediction of the decrease rate occurrence interval, and the verification items such as p_value is 0.5 or less and ecof appears in one direction through the SARIMA model, which is suitable for regular and clear time series data models, ensure reliability. Significant results were obtained. As a result of analyzing the temperature change by time zone and the water reduce ratio by section using the data secured based on such trust, the water reduce ratio is the highest in the 29-31 ℃ section from 12:00 to 13:00 from July to August. found to show. If a factor in the research result interval occurs using the research results, it is expected that the batch plant will produce Ready-mixed concrete that reflects the water reduce ratio at the time of designing the water-cement mixture, and prevent the decrease in concrete compressive strength due to the water reduce ratio.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.63-64
• /
• 2023

In order to reduce the high absorption ratio of spent coffee grounds, this study examined the compressive strength and absorption ratio of mortar replacing coated spent coffee grounds according to the type of water repellent. In order to examine this, as the water repellent used, a silane-based water repellent (fluorine-based water repellent) and an acrylic-based water repellent, which are film-type water repellents, and a silane/siloxane-based water repellent, which are penetration-type water repellents, were used. The spent coffee grounds were coated with each of three water repellents, and mortar was prepared by mixing cement and fine aggregate. As a result of the experiment, the compressive strength and absorption ratio of the mortar replaced with coated spent coffee grounds coated with the film-type water repellent were superior to the penetration-type water repellent. Therefore, in order to reduce the high absorption ratio of spent coffee grounds, a suitable water repellent is a film-type water repellent. Among them, it is judged that the acrylic type has excellent water repellency and is suitable.

• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.614-625
• /
• 2004

The main purpose of this study is to get flowrate coefficient 'q' and to study characteristics of flowrate of screw pump. This study is based on Muskin's formula and depends on the computer simulation. The results of study are as follows. 1. Flowrate coefficient will reduce according to increase of inclination. The larger the pitch ratio is and the smaller the diameter ratio is, the more coefficient reduces. 2. As a rule, the coefficient increases according to reduction of the diameter ratio, but the coefficient tends to reduce when the ratio is less than 0.45. So, in actual application, it is recommended that the ratio should be above 0.45. 3. If the pitch ratio increases, the coefficient increases in case of small inclination and decreases in case of large inclination. 4. The coefficient increases according to number of windings. Especially, singles winding is not used in actual application because it has too small coefficient. 5. The coefficient decreases when the influent water level falls. Flowrate is almost zero when the water level is below $40\%$ of Filling Points.

• Computers and Concrete
• /
• v.3 no.5
• /
• pp.357-373
• /
• 2006

The concepts of four parameters of nominal water-cement ratio, equivalent water-cement ratio, average paste thickness, fly ash-binder ratio were introduced. It was verified that the four parameters and the mix proportion of mortar can be transformed each other. The behaviors (strength, workability, et al.) of mortar primarily determined by the mix proportion of mortar now depend on the four parameters. The prediction models of strength and workability of mortar were built based on artificial neural networks (ANNs). The calculation models of average paste thickness and equivalent water-cement ratio of mortar can be obtained by the reversal deduction of the two prediction models, respectively. A mortar mix proportion design algorithm was proposed. The proposed mortar mix proportion design algorithm is expected to reduce the number of trial and error, save cost, laborers and time.

• Journal of Korean Society on Water Environment
• /
• v.37 no.3
• /
• pp.175-189
• /
• 2021

In this study, 48 streams in the Sapgyo Watershed were selected, and the Load Duration Curves (LDC) were drawn up for each stream using water quality and flow monitoring over the last three years (2018-2020), and it was evaluated whether the target water quality was achieved for each flow section. As a result of evaluating whether or not the target water quality exceeded according to the LDC, it was found that 22 rivers exceeded the target water quality. Five rivers exceeded the target water quality due to point pollutant sources, 13 rivers exceeded the target water quality due to non-point pollutant sources, and 4 rivers exceeded the target water quality due to both point and non-point pollutant sources. Among the rivers that exceeded the target water quality due to point pollutant sources, which included domestic sewage of the untreated population, there is a need to reduce the influx of polluted loads by the untreated population. The use of eco-friendly fertilizers is recommended for rivers with a relatively high farmland ratio among rivers exceeding the target water quality due to non-point pollutant sources, and installation of boiling point reduction facilities that can reduce the amount of polluted load introduced during rainfall or manage water shores. In rivers with a large number of livestock breeding heads, the livestock houses located in these rivers need to be preferentially transferred to livestock manure treatment plants. Due to the high ratio of land area because of urbanization, initial rainwater treatment facilities are required to reduce the amount of pollutant load flowing into the river through the impermeable layer during rainfall.

• Journal of Korean Society on Water Environment
• /
• v.26 no.3
• /
• pp.439-445
• /
• 2010

An emergy analysis of the main energy flows driving the economy of humans and life support systems consists of environmental energies, fuels, and imports, all expressed as solar emjoules. Total emergy use (371 E20 sej/yr) of the Western Nakdong River Basin is 97 per cent from imported sources, fuels and goods and services. Emergy flows from the environment such as rain and geological uplift flux accounted for only 2.9 percent of total emergy use. Emergy yield ratio and environment loading ratio were 1.03 and 33.27, respectively. Emergy sustainability index, a ratio of emergy yield ratio to environment loading ratio, is therefore less than one, which is indicative of highly developed consumer oriented economies. It is necessary for an efficient management of Western Nakdong River Basin to reduce pollution load basically and to restructure economic activities into an environmental friendly industrial structure depending on renewable energy and resources.

• Journal of Korean Society of Water and Wastewater
• /
• v.31 no.1
• /
• pp.51-62
• /
• 2017

For the asset management of a water pipe network, it would be necessary to understand the extent of the maintenance cost required for the water pipe network for the future. This study would develop a method to draw the optimum cost required for the maintenance of the water pipe network in waterworks facilities to maintain the aim revenue water ratio and to achieve the target revenue water ratio, considering the water service providers' waterworks condition and revenue water ratio comprehensively. This study conducted a survey with 96 water service providers as of the early 2015 and developed models to estimate the optimum maintenance cost of the water pipe network, considering the characteristics of the water service providers. Since the correlation coefficient of all the developed models was higher than 0.95, it turned out that it had significant reliability, which was statistically significant. As a result of applying the developed models to the actual water service providers, it was drawn that increasing revenue water ratio to more than a certain level can reduce the maintenance cost of the water pipe network by a great deal. In other words, it is judged that it would be the most efficient to secure the reliability of waterworks management by increasing the short-term revenue water ratio to more than a certain level and gradually increase the revenue water ratio from the long-term perspective. It is expected that the proposed methodology proposed in this study and the results of the study will be used as a basic research for planning the maintenance of water pipe network or establishing a plan for waterworks facilities asset management.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.576-579
• /
• 2004

In order to offer the condition of plant survival, present the method to reduce pH of porous concrete. Water curing is the most suitable method for reducing pH. Water/cement ratio is lower pH in $25\%$ than $30\%$, and to reduce pH, the larger size of coarse aggregate is more proper in the same water/cement ratio, neutralization management after becoming solid than early.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.04a
• /
• pp.202-207
• /
• 1996

Recently, the mortar crack on floor is very serious in construction field, e.g. the crack due to plastic shrinkage and the crack due to drying shrinkage. To prevent this kind of crack, optimum mix propertions not only satisfying the required workability but also minimizing the unit water content were selected. And the expansion admixtures were used to compensate the shrinkage of mortar. This study shows that water/cement ratio used in construction field is about 64%. Even if we reduce water/cement ratio of mortar by the appropriate use the fine aggregate with high fineness modulus and superplastizer, floor mortar can have the required workability. The equations between mortar flow and water/cement ratio, sand/cement ratio, fineness modulus of fine aggregate were proposed in this study. And this equation may provide available mix proportions of floor mortar.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.75-78
• /
• 2003

This study is to investigate the probability to develop the AE Water-reducing agent which can decrease the bleeding by mixing melamine type super-plasticizer(SP) and methyl cellulose(MC) viscosity agent. According to the result, as the mixing ratio of melamine type SP and MC viscosity agent increases, the bleeding is reduced due to a increase of the air content. When the mixing ratio of melamine type SP and MC viscosity agent is 1:2 and 1;3 at the water content of 165kg/$m^3$ and 175kg/$m^3$ respectively, slump and air content are satisfied and bleeding is reduced to some extent, so this is determined as the mixing ratio of AE water reducing agent for reduction of bleeding. It is prove that the developed AE water reducing agent for reduction of bleeding can reduce the amount of bleeding and prohibit the plastic shrinkage crack by slowing down the bleeding speed. Compressive strength of hardened concrete does not make any difference in comparison with plain concrete.