• Journal of Wetlands Research
• /
• v.7 no.3
• /
• pp.67-73
• /
• 2005

At research, the river's water which the sewage treatment facility will ask growth suppression the algae in the artificial rivers which it is using or it researched the method for the removal of the algae which grew. At results, when 60ppm of Chlorine was put in, the possibility of getting the result where 90% chlorophyll-a was removed and LC50 was 0.8ppm. The algae did not create even after 20days by which uses prevent agent of creation of the algae. Controlling the chlorine almost there was not an extinction effect of the algae which was already in large quantities multiplied, with in the effect against an water ecosystem widely known it is not. The prevent agent could inhibit creation of the algae, but it was judged with the fact that the methods are directly applied to the field must be researched continuously.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.6
• /
• pp.543-550
• /
• 2018

The RC buildings which are constructed on the seaside are followed by KBC(2016) to achieve the minimization of durability damage. To control the corrosion of the reinforcing steel bar by salt attack, W/C should be under 0.4 and specified concrete strength is higher than 35MPa in the concrete/building construction standard specification. Even though it has been proved that the concrete mixed with mineral admixture such as blast furnace slag and fly ash etc. have high strength and durability in previous researches, the beneficial informations are not applied to the codes. Ready-mixed concretes which usually include the admixtures in Busan were tested to certify the salt attack durability. In the same specified concrete strength, remarkable salt attack durability was evaluated in comparison to OPC. For economical and reliable durability design, chloride ion diffusivity should be measured before applying to new building construction.

• Journal of Korea Water Resources Association
• /
• v.47 no.3
• /
• pp.237-245
• /
• 2014

Volcanic ash components of Mt. Baekdu were estimated to response the change of water quality environment affected by Mt. Baekdu volcanic ash ejected during eruption. Then the change of water concentrations according to the sedimentation of volcanic ash components were analysed. To estimate volcanic ash components of Mt. Baekdu, similar volcanos were selected through the comparison of main foreign volcano's magma type and the selected volcanic ash components supposed as Baekdu Mountain's. To analyse the change of water concentrations, the change of harmful components affected by volcanic ash sedimentation were analysed and the results were compared with domestic drinking water quality standard. As the result, Al, Cd, F, Fe, Pb, Mg, Cl and Sr could affect to water quality. Among those components, concentrations of Cd, F, Fe, Pb and Mg were estimated to exceed the drinking water quality standard.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.31 no.3
• /
• pp.270-276
• /
• 1986

This experiment was conducted to find out the optimum fertilization level and topping depth for flue-cured tobacco in the fields which chinese cabbage and red-pepper were cultivated. The fertilization level were 0, 25, 50, 75kg per l0a as tobacco compound fertilizer and the topping depth were topping floral axis, topping under the second leaf frp, axos and the fourth leaf from floral axis. In order to product good quality tobacco leaves in the fields which vegetables were cultivated, the optimum amount of tobacco compound fertilizer was recommended 50-75kg per l0a for the field of the chinese cabbage cultivated. and 75kg per l0a for the field of the red-pepper cultivated. The optimum topping depth was desirable at topping under second leaf from floral axis for good leaf quality in chinese cabbage and red-pepper cultured field.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.545-548
• /
• 2008

As the corrosion of reinforcing bar in concrete structures exposed to chloride attack is one of main factors to determine the remaining service life, marine concrete structures have to be designed to protect the chloride penetration. Among the durability design methods such as deterministic method and probabilistic method, design method based on the probabilistic theory has been widely studied. However, the most essential material, data of the material properties related to chloride diffusion, are still insufficient. In this paper, the probabilistic distribution of chloride diffusion coefficients and aging coefficients are derived by the experiment and analysis for the chloride coefficients of concrete containing pozzolans, which are generally used in marine structures.

• Journal of Korean Society of Water and Wastewater
• /
• v.12 no.2
• /
• pp.90-98
• /
• 1998

The optimal rechlorination in water distribution systems was investigated by incorporating optimization techniques into a numerical water quality model. For a hypothetical system that consists of 10 junctions including a storage tank and 12 links, the bulk ($k_b$) and pipe-wall ($k_w$) decay-rate constants of chlorine residual are assumed to be 2.0 1/day and 1.5 m/day, respectively. It was also assumed that the lower and upper limits of chlorine residual in the network are 0.2 mg/L and 0.6 mg/L. When the chlorine source is only the storage tank (without rechlorination), the high levels of chlorine residual appear near the storage tank to maintain the chlorine residuals above the lower limit over the junctions. On the other hand, the chlorine residuals in the network are distribute within the desirable range (0.2 - 0.6 mg/L) after the optimal rechlorination through five injection sites including the storage tank. In case of a real water distribution system that comprises 28 junctions including a clear well and 27 links, the bulk and pipe-wall decay-rate constants are 0.3 1/day and 0.2 m/day, respectively. Before rechlorination, the required chlorine residual at the clearwell is 5.1 mg/L to keep the chlorine residuals above the minimum level (0.6 mg/L) over the junctions. By the optimal rechlorination at five injection sites, the chlorine residuals are distributed within a desirable range of 0.6 mg/L through 2.0 mg/L, which can avoid the excess of chlorine residuals near the clear well. Consequently, total chlirine doses are decreased by 81% in the hypothetical distribution network and 69 % in the real distribution network for satisfying the minimum chlorine residuals.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.3
• /
• pp.285-291
• /
• 2016

There has been an accelerating increase in water reuse due to growing world population, rapid urbanization, and increasing scarcity of water resources. However, it is well recognized that water reuse practice is associated with many human health and ecological risks due to numerous chemicals and pathogenic microorganisms. Especially, the potential transmission of infectious disease by hundreds of pathogenic viruses in wastewater is one of the most serious human health risks associated with water reuse. In this study, we determined the response of different bacteriophages representing various bacteriophage groups to chlorination in real wastewater in order to identify a more reliable bacteriophage indicator system for chlorination in wastewater. Different bacteriophages were spiked into secondary effluents from wastewater plants from three different geographic areas, and then subjected to various doses of free chlorine and contact time at $5^{\circ}C$ in a bench-scale batch disinfection system. The inactivation of ${\phi}X174$ was relatively rapid and reached ~4 log10 with a CT value of 5 mg/L*min. On the other hand, the inactivation of bacteriophage PRD1 and MS2 were much slower than the one for ${\phi}X174$ and only ~1 log10 inactivation was achieved by a CT value of 10 mg/L*min. Overall, the results of this study suggest that bacteriophage both MS2 and PRD1 could be a reliable indicator for human pathogenic viruses for chlorination in wastewater treatment processes and water reuse practice.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.6
• /
• pp.180-188
• /
• 2020

To replace Japanese coal ash used in the domestic cement production and to recycle large quantities of domestic pond ash, it is essential to develop the technologies for quality control of cement by using the domestic pond ash. Thus, in this study, the feasibility of using the pond ash as a raw material for cement was investigated through chemical composition and microstructure analysis. As a result, most of the domestic pond ash contained slightly more Fe2O3, chloride, and unburned carbon contents than Japanese coal ash. In particular, the contents of chloride were considerably low in the pond ash that was transferred to fresh water or collected from surface of landfill area. However, since circulating fluidized bed boiler coal ash had relatively high SO3 contents causing durability problems of cement, it was not suitable for use as a raw material for cement. Thus, to replace Japanese coal ash with the domestic pond ash, it is necessary to introduce the adjustment of mixture proportion of cement raw materials and the process of removing chloride in the pond ash.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.215-216
• /
• 2010

This study investigated the development of high durability concrete under an oceanic region through the examination and comparison of the fundamental property and diffusion of chloride ion to apply a high durability admixture on the concrete.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.6 no.4
• /
• pp.289-296
• /
• 2018

In this study, we evaluated the feasibility and performance of LCD waste glass as a replacement for cement by using LCD waste glass powder which is generated from manufacturing process due to development of LCD industry. Experiments were carried out by replacing 10% and 20% cement of LCD waste glass with particle size of $12{\mu}m$ of LCD waste glass with OPC and particle size of $5{\mu}m$, respectively. Through experiments, basic properties, mechanical properties and durability of concrete were evaluated. Experimental results show that the compressive strength is high at 10% replacement ratio compared to 20%. The lower the particle size, the higher the strength. The durability test evaluated the chloride penetration performance through the chloride ion diffusion coefficient. The higher the substitution rate and the smaller the particle size, the lower the chloride ion diffusion coefficient and the better the OPC than the all substitution rate. As a result, LCD waste glass concrete with low granularity and proper replacement ratio is considered to be advantageous for durability under salt environment.