• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.37 no.1
• /
• pp.65-70
• /
• 2001

As consumption rate of energy increase rapidly, the facilities of fuel storage tank become large size. Almost all of the industry or public facilities storing fuel in underground fuel storage tank is manufactured by steel materials. Thus, this fuel storage tank made of steel materials is damaged by stray-current corrosion, it become destruction. If fuel storage tank is destructed, petroleum, oil and gas are leaked. So it bring about environmental pollution, energy loss, fire and explosion. Therefor, in this study, for study on the prevention of corrosion damage in underground fuel storage tank, it were investigated by corrosion and stray-current corrosion for SS 400 in dry sea sand and wet sea sand along to specific resistance. The main results obtained are as follows : As specific resistance decrease in wet sea sand, corrosion rate per year increase linearly, in case of back fill up wet sea sand in underground fuel storage tank, if the water is flow into dry sea sand, corrosion tendency of underground fuel storage tank is supposed sensitive.

• Journal of Environmental Health Sciences
• /
• v.29 no.1
• /
• pp.28-33
• /
• 2003

This study was carried out to treat sewage using sand trench combined with septic tank process in rural areas. In order to find optimum parameters, design and operation mode was changed from Run 1 to Run 4. In order to facilitate nitrification and T-P removal, diffuser and iron plate was installed in the 3rd trench of Run 2 period. The septic tank played a role as pre-application process of sand trench system. The removal efficiencies of COD, NH$_4$-N, T-P at steady state were 94.6%, 87.9% and 54.5%, respectively. Addition of diffuser and iron plate in the 3rd trench has increased the removal efficiencies of the NIL-N and T-P. In this system, denitrification were not occurred because of the high DO.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.489-492
• /
• 2007

Understanding the thermohydraulic processes in the aquifer is necessary for a proper design of the aquifer thermal energy utilization system under given conditions. Experimental and numerical test were accomplished to evaluate the relationship between the geothermal heat exchanger operation and hydrogeological conditions in the open-loop geothermal system. Sand tank experiments were designed to investigate the open-loop geothermal system. Water injection and extract ion system as open-loop borehole heat exchanger was applied to observe the temperature changes in time at injection well, extraction well and ambient groundwater. The thermohydraulic transfer for heat storage was simulated using FEFLOW for two cases of extraction and injection phase operation in sand tank model. As one case, the movement of the thermal plume was simulated with variable locations of injection and extraction well. As another case, the simulation was performed with fixed location of injection and extraction well. The simulation and experimental results showed that the temperature distribution depends highly on the injected water temperature and the length of injection time and the groundwater flow and pumping rate sensitively affect the heat transfer.

• Journal of Korean Society on Water Environment
• /
• v.31 no.4
• /
• pp.418-427
• /
• 2015

This study was carried out to evaluate the performance of a lab-scale novel septic tank system for improving the conventional septic tank in the developing countries of water shortages. The lab-scale novel septic tank system consists of sepetic tank, aeration tank with HBC-ring, and sand filter. Optimum HRT was reguired about 1.5days to get a total COD removal efficiency of 90%, COD, BOD and SS removal efficiency was about 70%, 60%, and 85% in sepetic tank only. The structure of sepetic tank with two stages results in the high removal efficiency of organic matter. When sepetic tank, aeration tank, and sand filter were more than HRT 1.5days, 18hrs, and 12hrs, respectively, final effluent was less than 20 mg/L of BOD, 14 mg/L of SS, so that there is a high potential of its use for reusing water in flush toilet. There is no significant effect of HRT change on nutrient removal. Total nitrogen removal efficiency was about 40%, final effluent was 30~40 mg/L of TN, total phosphorus removal efficiency was about 11~25%, final effluent was 9~12 mg/L of TP. Because there is very small amounts of organic nitrogen and phosphorus in effluent, it was possible to reuse water for agricultural use.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.5
• /
• pp.889-898
• /
• 2022

In this study, sand casting process was applied to manufacture a large aluminum turbo-type fan used for tank powerpack. To apply the sand casting method, the turbo fan was reverse engineered, and after designing three gating systems, the optimal gating system design was selected by performing casting simulation. In the case of the bottom up-gating system, there is a significant temperature loss of the molten alloy during blade filling. When the molten alloy is completely filled into the sand mold, the blade upper tip and front shroud are below the liquidus temperature. In the case of the top down-gating system, molten alloy scattering occurs, but the temperature loss while the blade is filled is smaller than that of the bottom up type. And after the inflow of molten alloy into the mold is completed, the blade upper tip and front shroud are higher than the liquidus temperature. A sand mold was manufactured with the top down-gating system and the casting process was performed. The fan was made perfectly in appearance without any unfilled parts.

• Korean Journal of Organic Agriculture
• /
• v.8 no.1
• /
• pp.79-88
• /
• 1999

In order top investigate the growth of water dropwort grown by sandculture irrigated with recirculated tilapia aquaculture water, these experiments were carried out. Fish(tilapia) production and biofiltration provided by sand cultured water dropwort(Oenanthe stolonifera DC.) were linked in a closed system of recirculation water. Water dropwort was irrigated with water drawn from the tilapia tank and drainage from sand beds was returned to the fish tank. The temperature, pH and EC of tilapia culture water were stable. The growth of water dropwort grown by sandculture with aquaculture water was normal. Microbial activity of the biofilterbed irrigated by tilapia rearing water was higher than that of biofilterbed irrigated by tapwater. The feasibility of an integrated, recirculatory system for concurrent production of water dropwort and fish with no additional fertilization application was demonstrated.

• Journal of Aquaculture
• /
• v.22 no.1
• /
• pp.118-121
• /
• 2009

This experiment was conducted to evaluate the effects of different substrates in rearing tank on growth and body composition of juvenile sea cucumber Apostichophus japonicus. Sea cucumber (average weight 3.6) were randomly distributed at a density of 10 juvenile per tank into nine tanks providing three different substrates including free-substrates, sand and wave-shaped plastic sheet as (shelter). Juveniles were fed with a commercial feed once in every 2 days for 8 weeks. At the end of the experiment, survival of sea cucumber was not affected by the presence of substrates (P>0.05). Weight gain and specific growth rate of sea cucumber reared in the tanks with sand were significantly higher than those of sea cucumber reared in the tanks with shelter and without substrate (P<0.05). Crude protein and crude lipid of whole body in sea cucumber reared in free-substrate tanks were significantly higher than those of juvenile reared in the tanks with other substrates (P<0.05). Higher ash content was obtained in sea cucumber reared in the tanks with sand compared to that of juvenile reared in the tanks with other substrates (P<0.05). The results of this study suggest that growth and proximate composition of whole body of sea cucumber was significantly affected by substrates. Among materials tested, sand may be a proper substrate for sea cucumber culture.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2007.11a
• /
• pp.23-26
• /
• 2007

In this study, recently it is urgently required that demolition waste concrete has to be recycled on the construction because urban development is accelerated and redevelopment project is rapidly expanded, production quantity of construction and demolition waste concrete is being increased. On the other hand, it has to be solved urgently the unbalance of demand and supply about the fine aggregate because the sea sand is restricted by exhaustion of river sand and intensification of environment influence evaluation. Therefore, the purpose of the study was to show the performance of the apparatus developed by the study and to propose the direction of the optimum operating conditions by having an experimental and positive evaluation about quality of recycled sand produced to develop a separating and selecting device of impurities for recycling of construction wastes which can have a bigger improvement of economical efficiency, productivity, environmental property and quality through a basic property of matter of recycled sand by each operating condition of sand flux in comparison with the existing production system of recycled sand.

• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.3
• /
• pp.307-311
• /
• 2004

The objective of this work is to evaluate the hypothesis that a good technique for supplying oxygen to the saturated zone in the presence of light nonaqueous phase liquid (LNAPL) pool contamination at the water table is to pass air through the unsaturated zone above the pool. This hypothesis was evaluated in experimental studies performed using a bench-scale, sand-tank reactor, Steady-state abiotic experiments in the sand-tank reactor with air flowing through the reactor headspace demonstrated that oxygen supply through the water table interface into the saturated zone was enhanced when an LNAPL (dodecane) pool was present at the water table. These experimental results confirmed the hypothesis that an LNAPL pool can serve as a high concentration oxygen source to the oxygen-limited area beneath the pool and, as a result, enhance the in situ biodegradation rate.

• Journal of Soil and Groundwater Environment
• /
• v.20 no.2
• /
• pp.41-46
• /
• 2015

The drag of the excess charge in an electrical double layer at the solid fluid interface due to water flow induces the streaming current, i.e., the streaming potential (SP). Here we introduce a sandbox experiment to study this hydroelectric coupling in case of a tracer test. An acrylic tank was filled up with homogeneous sand as a sand aquifer, and the upstream and downstream reservoirs were connected to the sand aquifer to control the hydraulic gradient. Under a steady-state water flow condition, a tracer test was performed in the sandbox with the help of peristaltic pump, and tracer samples were collected from the same interval of five screened wells in the sandbox. During the tracer test, SP signals resulting from the distribution of 20 nonpolarizable electrodes were measured at the top of the tank by a multichannel meter. The results showed that there were changes in the observed SP after injection of tracer, which indicated that the SP was likely to be related to the solute transport.