• Journal of Soil and Groundwater Environment
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• v.15 no.2
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• pp.10-17
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• 2010

Advanced oxidation processes (AOPs) have advantages to reduce the processing time and mineralize contaminants dissolved in groundwater. Recently, remediation techniques for organic contamination in groundwater have been studied, and technology using $UV/H_2O_2$ is generally accepted as one of the most powerful and reliable alternative for the remediation of groundwater contamination. In this study, $UV/H_2O_2$ technology, which generates hydroxyl radical ($\cdot$ OH) as known for strong non-selective oxidant, was used to degrade chlorinated solvents (TCE and PCE), and it was expanded to apply continuous stirred tank reactor (CSTR) system (i.e. combinations of three CSTR). The tested parameters for CSTR system were retention time and groundwater/$H_2O_2$ injection volume ratio. To find optimum parameters for CSTR system, various retention time (6 min ~ 90 min) and groundwater/$H_2O_2$ injection volume ratio (5/1 ~ 119/1) were tested. Other conditions for CSTR were adapted from the batch test results, which concentration of $H_2O_2$ and UV dose were 29.4 mM (0.1%) and 4.3 kWh/L, respectively. Based on the experimental results, the optimum parameters for CSTR system were 20 min for retention time and 119/1 for groundwater/$H_2O_2$ injection volume ratio. Applying these optimum conditions, chlorinated solvents (TCE and PCE) were removed at 99.9% and 99.6%. Moreover, the effluent concentrations of TCE and PCE are 0.036 mg/L and 0.087 mg/L, respectively, which are satisfied the regulatory level (TCE 0.3 mg/L, PCE 0.1 mg/L). Consequently, the CSTR system using $UV/H_2O_2$ technology can achieve high removal efficiency in the event of treatment of groundwater contaminated by chlorinated solvents (TCE and PCE).

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.347-356
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• 1997

Solution copolymerization of Styrene(St) and n-Butylmethacrylate(BMA) was carried out with Benzoylperoxide (BPO) as an initiator in toluene at $80^{\circ}C$ in a continuous stirred tank reactor. Reaction volume and residence time were 0.6 liters, 3 hours respectively. The monomer reactivity ratios, $r_1$(St) and $r_2$(BMA) were determined by both the Kelen-Tlidos method and the Fineman-Ross method ; $r_1$=0.75(0.67), $r_2$=0.61(0.56). The cross-termination factor, $\phi$ factor of the copolymer over the entire St compositions ranged from 0.44 to 0.78. The $\phi$ factors of St-BMA copolymer increased with increasing St compositions. Our present system showed that the continuous copolymerization of St with BMA followed second-order kinetic behavior. The simulated conversions and copolymerization rates were compared with the experimental results. The average time to reach dynamic steady-state was three times and half of the residence time.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.188-199
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• 2013

This thesis is the fundamental study on the adaptation of escape device for reducing small size of fish in set-net. The escape devices for experiments were made the grid-type devices with three different slit sizes (15, 20 and 25mm). The experiments of size selectivity on escape devices were conducted by using two kinds of species as black rockfish (Sebastes schlegeli) and sea perch (Lateolabrax maculatusi) in the experimental tank. The size selectivity curve was fitted by using a logistic function and the parameters of selectivity curve were estimated by a maximum likelihood method. In the results; 50% selection ranges for the grid-type escape devices with three different slit sizes were; a black rockfish was 13.30, 19.22 and 22.06cm and a sea perch was 17.64, 20.91 and 22.78cm, respectively. The 50% selection range of a black rockfish was wilder than a sea perch about 1.1~1.3 time. Therefore, the small size of fish are able to reduce by using the grid type escape device. However, the optimum slit size of grid should be decided to consider the size of target species and economics of catches.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.1
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• pp.61-70
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• 2015

In an attempt to improve the maneuvering character of hull form renovated tuna purse seiner. A renovation was carried out on the 3 tuna purse seiner fishing vessel. To grasp the progress of maneuvering and resistance on ship B (730 ton class), new bulbous bow was only attached. The ship A (740 ton class) and C (600 ton class) were modified for new bulbous bow, enlarged slipway and rudder. And then the zigzag and the turning test were carried out. According to the turning test, the advance and the tactical diameter were improved very much for the modified ship. The sea trial was carried out for the original and modified ship A. It is showed that the results of sea trial corresponded with that of the tank test on the whole. In the result of the zigzag test on ship B, the turning ability was improved very much, but the yaw checking ability was deteriorated in just some degree. In the result of the zigzag test on ship C, the turning ability and yaw checking ability were remarkably improved. Ship C was greatly improved among the three ships for the maneuvering character of modified hull form.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2009.05a
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• pp.184-189
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• 2009

The Measurement system of auto parts are currently precious ones in the case of most of them. In this paper We tried to implement low_cost equipment. There are many auto parts. Among them CCP(Canister Controlled Purge Solenoid) which have difficulties in the control of air fluid currently have been main object. According to the use of air amount. Required time to maintain vacuum air pressure constantly need three or four minutes but the aim of this development try to achieve keeping vacuum pressure within less shorter time, Under the constant air pressure, We try to develop control check system of auto parts CCP(Canister Controlled Purge Solenoid).

• Journal of Power System Engineering
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• v.16 no.4
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• pp.17-23
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• 2012

In this study, the numerical simulation and basin model test have been performed to evaluate sea worthiness and resistance performance for a small pre-planning three type of leisure boats which are U, V, Y shapes of hull forms. As a well known commercial CFD code, Maxsurf, was applied for modeling hull forms used as the solver of motion analysis. Also the model resistance test was carried out to estimate the effective power of boat in the basin tank. Numerical simulation and model test results show that Y-shaped hull is better than the other types in terms of heave and pitch motion, having a key effect on a boat sea worthiness. But V-type hull is more efficiency than others cases in resistance performance.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1617-1628
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• 2017

In the passive residual heat removal system of a molten salt reactor, one of the residual heat removal methods is to use the thimble-type heat transfer elements of the drain salt tank to remove the residual heat of fuel salts. An experimental loop is designed and built with a single heat transfer element to analyze the heat transfer and flow characteristics. In this research, the influence of the size of a three-layer thimble-type heat transfer element on the heat transfer rate is analyzed. Two methods are used to obtain the heat transfer rate, and a difference of results between methods is approximately 5%. The gas gap width between the thimble and the bayonet has a large effect on the heat transfer rate. As the gas gap width increases from 1.0 mm to 11.0 mm, the heat transfer rate decreases from 5.2 kW to 1.6 kW. In addition, a natural circulation startup process is described in this paper. Finally, flashing natural circulation instability has been observed in this thimble-type heat transfer element.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.11-19
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• 2011

PADDIMOD2 was deloped to estimate nonpoint source pollution from paddy rice fields. The PADDIMOD2 was enhanced to estimate runoff and pollutant load during non-growing as well as growing season and to be easily used for public by development of Excel based system. Nutrient concentration and hydrology were based on Dirac delta function and continuous source function, and tank model for growing season and Event Mean Concentrations (EMCs) and SCS-Curve Number method for non-growing season. The PADDIMOD2 consists of three main component (input data, parameters data, and output data) by including eight Excel spread sheets. As a result of model application, total precipitation and irrigation were 1,051.7 mm and 439.2 mm, respectivley and surface runoff and water loss including infiltration and evapotranspiration were 463.0 mm and 947.9 mm, respectively. Annual nutrient loadings of T-N and T-P from study area were 6.7 kg/$km^2$/day and 0.5 kg/$km^2$/day, respectively. Development of PADDIMOD2 was focused on minimizing input data and maximizing user friendly system and is expected to be useful tool to evaluate various non-structure BMPs and estimate unit load from paddy rice fields for application at Korean TMDL.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.197.1-197.1
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• 2010

This study was carried out to evaluate the operating performances of the evaporation desalination system with solar energy. This system was designed to use evacuated solar collector as the heat source, supplying the required heat energy and photovoltaic power as the electric source, supplying required power to pumps in the desalination system. The 5kW photovoltaic power generation system to make the electricity, the single-stage fresh water generator with plate heat exchanger, and remote control and monitoring system. Solar desalination system was designed and installed in Jeju-island, Korea in 2006, after about 4 years of operation, usability and stability of solar desalination system was guaranteed. The system comprises of the desalination unit which was designed to have daily fresh water capacity of $2m^3$, a $120m^2$ evacuated tubular solar collector to supply the heat, a $6m^3$ heat storage tank, and a 5.2kW photovoltaic power generation to supply the electricity to hydraulic pumps for the heat medium fluids. On a clear day, average daily solar irradiance in Jeju-island was measured to be $500W/m^2$ and the daily fresh water yield showed to be more than 500 liters under this condition. After around three years of a long term operation of the system from January 2007 to August 2009, average daily freshwater yield was analyzed to be around $330{\ell}$. The relationship equation between solar irradiance and freshwater yield was found to be y=1.1806x - 107.89.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.163-169
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• 2012

We have conducted three experiments to develop a fertilizer-dissolving apparatus used in fertigation or hydroponics cultivation in order to decrease the fertilizer dissolving time and labor input via automation. All of the experiments were conducted twice. In the first experiment, four selected treatments were tested to dissolve fertilizers rapidly. The first treatment was to dissolve fertilizer by spraying water with a submerged water pump, placed in the nutrient solution tank. The water was sprayed onto fertilizer, which is dissolved and filtered through the hemp cloth mounted on the upper part of the nutrient solution tank (Spray). The second treatment was to install a propeller on the bottom of the nutrient solution tank (Propeller). The third treatment was to produce a water stream with a submerged water pump, located at the bottom of the tank (Submerged). Finally, the fourth treatment was to produce an air stream through air pipes with an air compressor located at the bottom of the tank (Airflow). The Spray treatment was found to take the shortest time to dissolve fertilizer, yet it was inconvenient to implement and manage after installation. The Airflow treatment was thought to be the best method in terms of the time to dissolve, labor input, and automation. In the second experiment, Airflow treatment was investigated in more detail. In order to determine the optimal number of air pipe arms and their specification, different versions of 6- and 8-arm air pipe systems were evaluated. The apparatus with 6 arms (Arm-6) that was made of light density polyethylene was determined to be the best system, evaluated on its time to dissolve fertilizer, easiness to use regardless of the lid size of the tank, and easiness to produce and install. In the third experiment, the Submerged and Arm-6 treatments were compared for their dissolving time and economics. Arm-6 treatment decreased the dissolving time by 8 times and proved to be very economic. In addition, dissolving characteristics were investigated for $KNO_3$, $Ca(NO_3)_2{\cdot}4H_2O$, and Fe-EDTA.