• Journal of Environmental Science International
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• v.24 no.11
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• pp.1485-1491
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• 2015

There are two treatment processes that are currently applied to ships are the biological treatment process using the activated sludge and the electrochemical treatment. However, neither of them are able to remove both nitrogen and phosphorus due to their limited ability to remove organic matters, which are main causes of the red tide. This study was conducted to identify the characteristics of nitrogen removal factors from manure wastewater by replacing the final settling tank in SBR (Sequencing Batch Reactor) process and applying immersion type hollow fiber membrane. SBR process is known to have an advantage of the least land requirement in special environment such as in ship and the immersion type hollow fiber membrane is more stable in water quality change. As the result, the average in the cases of DO (Dissolved Oxygen) is 2.9(0. 6~3.9) mg/L which was determined to be the denitrifying microorganism activity in anaerobic conditions. The average in the cases of ORP (Oxidation Reduction Potential) is 98.4~237.3 mV which was determined to be the termination of nitrification since the inflection point was formed on the ORP curve due to decrease in the stirring treatment after the aeration, same as in the cases of DO. Little or no variation in the pH was determined to have positive effect on the nitrification. T-N (Total Nitrigen) removal efficiencies of the finally treated water were 71.4%, 72.3% and 66.5% in relatively average figures, thus was not a distinct prominence. In being applied in ships in the future, the operating conditions and structure improvements are deemed necessary since the MEPC (Marine Environment Protection Committee). 227(64) ship sewage nitrogen is less than the standard of 20 Qi/Qe mg/L or the removal rate of 70%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.167-175
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• 2018

Natural gas is a clean fuel that discharges almost no air-contaminating substances. This study examined the simultaneous reduction of $CH_4$ and NOx of NGOC/LNT catalysts for CNG buses related to the improvement of the $de-CH_4/NOx$ performance, focusing mainly on identifying the additive catalysts, loading of the washcoat, stirring time, and types of substrates. The 3wt. % Ni-loaded NGOC generally exhibited superior $CH_4$ reduction performance through $CH_4$ conversion, because Ni is an alkaline, toxic oxide, and exerts a reducing effect on $CH_4$. A excessively small loading resulted in insufficient adsorption capacity of harmful gases, whereasa too high loading of washcoat caused clogging of the substrate cells. In addition, with the economic feasibility of catalysts considered, the appropriate amount of catalyst washcoat loading was estimated to be 124g/L. The NOx conversion rate of the NGOC/LNT catalysts stirred from $200^{\circ}C$ to $550^{\circ}C$ for 5 hours showed 10-15% better performance than the NGOC/LNT catalysts mixed for 2 hours over the entire temperature range. The NGOC/LNT catalysts exhibitedapproximately 20% higher $de-CH_4$ performance on the ceramic substrates than on the metal substrates.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.643-649
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• 2007

Lipase-catalyzed esterification of structural butanol isomers and n-butyric acid was investigated in supercritical carbon dioxide. The experiments were performed in a high pressure cell for 5 hrs with a stirring rate of 150 rpm at 323.15 K and 130 bar. The Candida Antarctica lipase B (CALB) was used in whole system as a catalyst. The experimental results were analyzed by GC-FID using a INNOWax capillary column. The conversion yield and the tendency of the esterification in supercritical carbon dioxide were compared with estimated results by molecular dynamics simulation. Based on the Ping-Pong Bi-Bi mechanism with competitive inhibition, each step of the reaction was optimized; using this result the transition state was predicted. Conformational preference of isomers was also analyzed using molecular dynamics simulations. This kind of approach will be further extended to the prediction of enzyme-catalyzed reactions using computers.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.86-92
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• 2012

A characteristic study of chlorine dioxide generation by the electrolysis system was performed after chlorite ($ClO_2^-$) is adsorbed from sodium chlorite by a polymer ion exchange resin. A strongly basic anion exchange resin was used and a Ti plate coated with Ru and Ir was used as an electrode. Various parameters such as reaction stirring velocity, reaction temperature, chlorine dioxide product concentration, ion exchange resin content and product maker type for the adsorption quantity in the chlorite adsorption of ion exchange resin were investigated and found the ion exchange resin with the maximum adsorption quantity. A generation trend of chlorine dioxide was observed by the electrolysis system and optimum conditions on the desired value were found using response surface design of DOE (Design of Experiments). The strongly basic anion exchange resin with the maximum adsorption quantity was SAR-20 (TRILITE Gel type II) and the adsorption quantity was around 110 mg/IER (g). Observed generation optimum conditions of chlorine dioxide were constant-current (electrode area base; $A/dm^2$) and flow rate of $N_2$ gas (4.7 L/min) at the desired value of sterilization (900~1000 ppm, 1 h).

• Clean Technology
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• v.13 no.1 s.36
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• pp.34-45
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• 2007

Phase behavior of the ternary systems of water-insoluble simvastatin drug, which is well known to be effective drugs for hypercholesterolemia therapy, in solvent mixtures of dichloromethane and supercritical carbon dioxide was investigated to present a guideline of establishing operating conditions in the particle formation of the drugs by a supercritical anti-solvent recrystallization process utilizing dichloromethane as a solvent and carbon dioxide as an anti-solvent. The solubilities of simvastatin in the mixtures of dichloromethane and carbon dioxide were determined as functions of temperature, pressure and solvent composition by measuring the cloud points of the ternary mixtures at various conditions using a high-pressure phase equilibrium apparatus equipped with a variable-volume view cell. The solubility of the drug increased as the dichloromethane composition in solution and the system pressure increases at a fixed temperature. A lower solubility of the drug was obtained at a higher temperature. The second half of this work is focused on the particle formation of the simvastatin drug by a supercritical anti-solvent recrystallization process in a cylindrical high-pressure vessel equipped with an impeller. Microparticles of the simvastatin drug were prepared as functions of pressure (8 MPa to 12 MPa), temperature (303.15 K, 313,15 K), feed flow rate of carbon dioxide, and stirring speed (up to 3000 rpm), in order to observe the effect of those process parameters on the size and shape of the drug microparticles recrystallized.

• Journal of the Korean Applied Science and Technology
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• v.38 no.5
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• pp.1325-1334
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• 2021

This study reports the development of a manufacturing method of synthesizing colloidal gold using catalysts available for cosmetics and an anti-aging ampoule with skin improvement effects using it. Nano-colloidal gold was synthesized by using ascorbic acid and sodium borohydride as a reducing catalyst in hydrogen tetrachloroaurate tetrahydrate. It was confirmed that the particles became smaller as the mass of the content of ascorbic acid, which is a catalyst, increased. On the other hand, as the mass of sodium borohydride increased, the particle size tended to increase. In order to control the colloidal gold reaction rate, particles having 100 to 500 nm of a particle diameter distribution could be obtained using xanthan gum and hydroxyethylcellulose. The optimal synthesis conditions could be obtained by reacting for 1 to 4 hours at 18℃, a reduced pressure state of 20 to 75 mmHg, a stirring speed of 10~50 rpm. The synthesized colloidal gold had a unique smell of dark pink, pH = 5.5, specific gravity of 1.0032, and viscosity of 80 to 310 cps. As an application of skin care cosmetics, anti-aging ampoule has been developed, and it is expected to be used for various prescriptions and formulations using it.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.81-88
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• 2018

This study analyzed the characteristics of 6 recyclable bulking agents which can replace sawdust and rice hulls that are commonly used in livestock manure composting. The content of all the hazardous chemicals found in the bulking agents used in this experiment was between 0.0 and 34.1 ppm, which was noticeably lesser than the maximum content levels of hazardous substances 5.0~900.0 ppm prescribed by the Rural Development Administration(RDA), which means that the bulking agents would be able to replace sawdusts and rice husks. The water content of the bulking agents ranged from a minimum of 12.4% to a maximum of 16.6% in the original state, which was much less than 60%, the optimal moisture content. These results indicate that they would be able to function fully as bulking agents. Their water absorption rate was in the range of minimum 31.9% ~ maximum 600.0%, which showed huge differences among the types of bulking agents. The most appropriate bulking agent in terms of water absorption rate was wood pellets. It was the highest in the wood briquette manufactured by A, which was followed by C and B in the order. The shear strength of the 5 types of bulking agents in the original state was 271.7 N on an average, the highest figure of all, except for the oak briquette whose shear strength could not be measured and the wood pellets in the absorption state. The shear strength in the dry and absorption states then followed, and were 78.0 N and 27.7 N on an average, respectively. The wood briquette of A recorded considerably lower shear strength than that of B and C. Overall, shear strength tended to increase according to lower water absorption rates. Since pine wood chips and oak cuts have relatively greater shear strength even in the absorbing state than the other materials, they will be able to endure some power in the case of stirring with pig droppings.

• Radiation Oncology Journal
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• v.12 no.1
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• pp.27-31
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• 1994

There are a number of reports suggesting that there may be a correlation between the clinical response to radiotherapy in various tumors and the clonogenic survival of cell lines derived from these tumors following exposure to 2 Gy(SF2). Authors conducted this study to determine SF2 for cells in primary culture from surgical specimens. The tumor tissues with squamous cell carcinoma of uterine cervix and head and neck were obtained. The tumor tissues were disaggregated to single cells by incubating with collagenase type w for 2 hours with constant stirring. Single cell suspensions were inoculated in four 24-well plates precoated with cell adhesive matrix. After 24 hours of incubation at 37$ ^{\circ}C $, rows of four wells were then irradiated, consisting of control set and five other sets each receiving doses of 1,2,3,4, and 6 Gy. After incubation for a total of 13 days, the cultures were stained with crystal violet and survival at each dose was determined by quantitative image analysis system, To determine whether cell growth was of epithelial origin, immunocytochemical staining with a mixture of cytokeratin and epithelial monoclonal antibodies were performed on cell cultures. During the period of this study, we received 5 squamous cell carcinoma specimens of head and neck and 20 of uterine cervical carcinoma. Of these, 15 yielded enough cells for radiosensitivity testing. This resulted an overall success rate of 60$ \% $. The mean SF2 value for 15 tumours was 0.55$\pm$0.17 ranging from 0.20 to 0.79. These results indicate that there is a broad range of sensitivities to radiation in same histologic type. So with a large patient population, we plan to determine whether a different SF2 value is associated with tumours that are controlled with radiotherapy than those that are not.

• Journal of agriculture & life science
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• v.53 no.5
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• pp.137-143
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• 2019

To manufacturing of solid fuel by reuse of the wastes, the drying unit which have 500 kg/hr of drying capacity was developed and experimentally evaluate the performance. The spinach grown in Nam-hae island were used for the experiments and investigated of the heated-air drying characteristics as the inlet amount of raw materials, raw material stirring status, conveying type and drying time. The drying air heated by the energy derived from the steam which is supplied from the incineration plant. The moisture contents of raw materials were measured 85.65%. The inlet flow rate of drying air made a difference as the depth of the raw materials loaded on the drying unit and temperature has showed 108~144℃. The drying speed of the mixed drying more than doubled as that of non mixed drying under the same drying type, inlet amount, drying time and drying air temperature. In each experiment, the drying capacity have showed over 500 kg/hr. A drying efficiency of the ratio of drying consumption energy to input energy was 33.46%, lower than the average of 57.76% for the 157 conventional dryers. Because developed dryer must have a drying time of less than one hour, it is considered that the dry efficiency has been reduced due to the loss of wind volume during drying. If waste heat from incineration plant is used as a direct heat source, the dry air temperature is expected to be at least 160℃, greatly improving the drying capacity.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.41-50
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• 2010

We have developed an in-situ benthic chamber (BelcI) for use in coastal studies that can be deployed from a small boat. It is expected that BelcI will be useful in studying the benthic boundary layer because of its flexibility. BelcI is divided into three main areas: 1) frame and body chamber, 2) water sampler, and 3) stirring devices, electric controller, and data acquisition technology. To maximize in-situ use, the frame is constructed from two layers that consist of square cells. All electronic parts (motor controller, pA meter, data acquisition, etc.) are low-power consumers so that the external power supply can be safely removed from the system. The hydrodynamics of BelcI, measured by PIV (particle image velocimetry), show a typical "radial-flow impeller" pattern. Mixing time of water in the chamber is about 30 s, and shear velocity ($u^*$) near the bottom layer was calculated at $0.32\;cm\;s^{-1}$. Measurements of diffusivity boundary layer thickness showed a range of $180-230\;{\mu}m$. Sediment oxygen consumption rate, measured in-situ，was $84\;mmol\;O_2\;m^{-2}\;d_{-1}$, more than two times higher than on-board incubation results. Benthic fluxes assessed from in-situ incubation were estimated as follows: nitrate + nitrite = $0.18\;{\pm}\;0.07\;mmol\;m^{-2}\;d^{-1}$ ammonium $23\;{\pm}\;1\;mmol\;m^{-2}\;d^{-1}$ phosphate = $0.09\;{\pm}\;0.02\;mmol\;m^{-2}\;d^{-1}$ and silicate = $23\;{\pm}\;1\;mmol\;m^{-2}\;d^{-1}$.