• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3173-3177
• /
• 2007

Recently, we have many problems on the process of the sludge. In past, the sewage sludge was treated by reclaimed land or thrown away in the sea. But these methods caused environmental pollution. Today, many researchers are studying various methods for reducing its volume. One of these method, this study is to reduce the moisture of sewage sludge and to solidify it using a dryer and curing equipment. In this research, we investigated about design parameter and operation condition of the equipment. The curing equipment reduces the percentage of water content from 30% of dryer to 10%. So, we have to study the curing characteristics and performance of curing equipment. For example, there are internal flow characteristics and change of the percentage of water content. And we investigated the change of data at outlet along the initial condition, temperature, humidity and air flow. Using this data, we achieve the experimental results of curing efficiency by each geometry and operating condition. And we also investigated numerical analysis of internal flow using CFD code. This research is basic study for optimal design of the curing equipment.

• Korean Journal of Environmental Agriculture
• /
• v.24 no.1
• /
• pp.12-16
• /
• 2005

As a silicate source to rice, a coal ash was selected and mixed with phosphor-gypsum (50:50, wt $wt^{-1}$) to reduce the potential of boron toxicity and to supply calcium element. We expected that high con tent of calcium in this mixture might convert water-soluble phosphorus to less soluble forms and then reduce the release of soil phosphorus to surface runoff. The mixture was applied with the rate of 0, 20, 40, and 60 Mg $ha^{-1}$ in paddy soil (Nagdong series, a somewhat excessively drained loamy fine sand) in Daegok, Jinju, Korea The mixture reduced significantly water-soluble phosphorus (W-P) in the surface soils by shifting from W-P and Fe-P to Ca-P and Al-P during whole rice cultivation. In contrast with W-P, plant available phosphorus increased significantly with the mixture application due to high content of phosphorus and silicate in the mixture. The mixture of coal ash and phosphor-gypsum (50:50, wt $wt^{-l}$) would be a good alternative to reduce a phosphorus export in rice paddy soil together with increasing rice yields.

• Preventive Nutrition and Food Science
• /
• v.22 no.3
• /
• pp.216-222
• /
• 2017

Antioxidant rich green leafy vegetables including garden spinach leaf, water spinach leaf, Indian spinach leaf, and green leaved amaranth were selected to evaluate the effects of water boiling and oil frying on their total phenolic content (TPC), total flavonoid content (TFC), reducing power (RP), and antioxidant capacity. The results revealed that there was a significant increase in TPC, TFC, and RP in all the selected vegetables indicating the effectiveness of the cooking process on the antioxidant potential of leafy vegetables. Both cooking processes enhanced significantly (P<0.05) the radical scavenging ability, especially the oil fried samples showed the highest values. There is a significant reduction in the vitamin C content in all the vegetables due to boiling and frying except in the Indian spinach leaf. However, the present findings suggest that boiling and frying can be used to enhance the antioxidant ability, by increasing the bioaccessibility of health-promoting constituents from the four vegetables investigated in this study.

• Journal of Industrial Technology
• /
• v.22 no.A
• /
• pp.177-184
• /
• 2002

Reinforced concrete(R/C) is commonly used to structures because they have many merits that compressive strength, economy and so on. However, reinforced concrete has a crack at the tensile section which is due to the relatively lower tensile strength than its compressive strength Latex modified concrete(LMC) has higher tensile and flexural strength than the ordinary portland cement, due to the interconnections of hydrated cement and aggregates by a film of latex particles. The purpose of this study was to investigate the flexural behavior of reinforced concrete beam with latex modified concrete, having the main experimental variables such as concrete types(ordinary portland cement concrete, latex modified concrete), latex contents(0%, 15%), flexural steel ratios(0.012, 0.0235), and with/without shear reinforcement. The beam of LMC showed considerably higher initial cracking loads and ductility than that of OPC, but, similar to ultimate strength and deflection. This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation. The beam with latex modified concrete could be adopted at field for controlling and reducing the tensile crack due to its higher tensile strength.

• The Korea Journal of Herbology
• /
• v.22 no.2
• /
• pp.127-135
• /
• 2007

Objective : Investigation of the anti-stress effects of Sihosogansan Methods : Passive avoidance test(PAT) was performed after applying immobilization stress in water to rats. Also, forced swimming test(FST) was performed to another rats and after FST, the degree of Tyrosine Hydroxylase(TH) expression was measured with immunohistochemical method in the regions of locus coeruleus(LC) and ventral tegmental area (VTA). Results : In the PAT after immobilization stress in water, response latency was significantly increased in the Sihosogansan(400mg/kg) group in comparison with the control group. In the FST, immobility was significantly decreased in the Sihosogansan groups (100mg/kg, 400mg/kg), comparing with the control group. Stress-induced TH increases were suppressed in the Sihosogansan groups (100mg/kg, 400mg/kg) at the LC and the VTA region respectively. Conclusion : Sihosogansan can improve memory ability of rats, reduce behavior of depression in rats, decrease TH-immunoreactive cells at the LC and VTA region in rat, and it may be concluded that Sihosogansan has significant effect in reducing stress.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.3
• /
• pp.1-8
• /
• 2006

The objective of this research is to study on the analysis of long-term performance characteristics of various solar thermal system for heating protected horticulture system for reducing heating cost, increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Long term field test for the demonstration was carried out in horticulture complex in Jeju Island. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Optimum operating condition and its characteristics were closely investigated by changing the control condition based on the temperature difference which is the most important operating parameter. However, it is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• Journal of Korean Society on Water Environment
• /
• v.29 no.4
• /
• pp.459-465
• /
• 2013

A sequencing batch reactor was operated under different pH conditions to see the influence of pH to microbial community in enhanced biological phosphorus removal (EBPR) systems. Long term influences of different steady-state pH conditions on the microbial community composition were evaluated by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH). The shift in populations from polyphosphate-accumulating organisms (PAOs) to Alphaproteobacteria was observed when pH was changed from 7.5 to 7.0. Alphaproteobacteria with the typical morphological traits of tetrad-forming organisms (TFOs) eventually became dominant members. The alphaproteobacterial TFOs were the phenotype expected for glycogen-accumulating organisms (GAOs), which accumulate large amount of glycogen into the cell. The results strongly suggested that low operational pH condition encourages the appearance of the GAOs in EBPR process, significantly reducing the EBPR capacity.

• Journal of Korean Society of Water and Wastewater
• /
• v.19 no.5
• /
• pp.647-654
• /
• 2005

Recently, the economic losses caused by inundation are increasing due to the urbanization and industrialization, i.e., intensive land utilization and concentration of population and properties. It is regarded that the role of the storm sewer systems in urban areas becomes more important as one of the effective countermeasures for reducing the inundation losses. In this study, the effects of rainfall design frequency enhancement on the construction cost of the storm sewer systems were analyzed by increasing the design frequency from the present design frequency of the sewer systems, which is 5~10 years, to 15 years, 20 years and 30 years. The change rate functions of the design discharge and construction cost based on the various design frequencies were derived by regression analysis. According to the analysis, change the rate of design discharge at 15, 20, 30 years rainfall design frequencies were increased by 10%, 17.1%, and 27.2%, respectively, when compared to that at 10 year frequency. Furthermore, it was found that by increasing the design frequency from 10 years to 15 years, 20 years and 30 years, the construction costs were increased by 5.0%, 8.0% and 12.4%, respectively. Finally, their reliabilities need to be tested by applying the rate functions to the real storm sewer districts.

• Journal of Korean Society of Water and Wastewater
• /
• v.19 no.1
• /
• pp.53-60
• /
• 2005

Ferrous cement hydrates made from hydrating Portland cement doped with Fe (II) were reported to reductively dechlorinate chlorinated organics and to reduce Cr (VI) to Cr (III). In this study, kinetics of nitrate removal by ferrous cement hydrates were investigated. Nitrate removal kinetics were characterized by experimental variables such as cement hydration, amount of cement addition, Fe (II) dose, pH, and byproducts. As a result, hydrated cement showed better performances than non-hydrated cement due to the formation of LDH (layered double hydroxide). Doping of Fe (II) into the cement was found to improve removal efficiency at high pHs by association with Fe (II) sorbed on cement hydrates as a reactive reductant. Reduction of nitrate produced ammonium as a major product, which accounted for 63.5% of the final products, and nitrite (0.15%) as a minor product. These results indicate that the developed media are effective as sorbent/reducing agents in the nitrate removal and the reaction mechanisms of nitrate removal are sorption and reduction.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.3
• /
• pp.315-322
• /
• 2007

The purpose of this study was to investigate the biodegradability and performance of organic removal and methane production rate when treating piggery wastewater using a granule of two-phase anaerobic process applied UASB. BMP test was conducted as simple means to monitor relative biodegradability of substrate and to determine methane production of an organic material. The two-phase anaerobic process is consisted of a continuous flow stirred-tank reactor (CFSTR) for the acidification phase and an Upflow Anaerobic Sludge Blanket reactor (UASB) for the methanogenesis. The acidogenic reactor played key roles in reducing the periodically applied shock-loading and in the acidification of the influent organics. A stable maximum biogas production rate was 400mL. The methane contents ranged from 73 to 80% during the experimental period. It is known that most of the removed organic matter was converted to methane gas, and the produced biogas might be high quality for its subsequent use.