• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.531-537
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• 2014

A catalytic plasma reactor was employed for the oxidation of isopropyl alcohol (IPA) classified as a volatile organic compound (VOC). Copper oxide (Cu : 0.5% (w/w)) supported on a multichannel porous ceramic consisting of ${\alpha}-Al_2O_3$ was used as a catalyst, which was directly exposed to the plasma created in it. The effects of discharge voltage and reaction temperature on the concentrations of IPA and its byproducts were examined to understand the behavior of the catalytic plasma reactor. Without thermal insulation, the reactor temperature increased up to $120^{\circ}C$ at an applied voltage of 17 kV (discharge power : 28 W), and the IPA at a flow rate of $1L\;min^{-1}$ ($O_2$ : 10% (v/v); IPA : 1000 ppm) was completely removed. At temperatures below $120^{\circ}C$, however, besides the desirable product $CO_2$, several unwanted byproducts such as acetone, formaldehyde and CO were also formed from IPA. On the other hand, when the reactor was thermally insulated, the plasma discharge increased the temperature up to $265^{\circ}C$ under the same condition and most of IPA was oxidized to $CO_2$. Without loading CuO on the ceramic support, the plasma discharge in the thermally insulated reactor produced nearly equal amounts of $CO_2$ and CO. On comparison, with the catalyst alone (temperature : $265^{\circ}C$), more than 70% of the removed IPA was simply converted into another type of VOC (acetone), indicating that the catalyst assisted by the plasma is more effective in the oxidation of IPA than that of the catalyst-alone process.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.620-631
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• 2022

This paper shows the numerical prediction of the change in oil outflow rate according to the orifice shape of a damaged ship by using the computational fluid dynamics (CFD) analysis method. It also provides discharge coefficients for various orifice shapes to be used in theoretical prediction approaches. The oil outflow from the model ship was analyzed using a multiphase flow method under the condition that the Froude and Reynolds number similitudes were satisfied. The present numerical results were verified by comparing them with the available experimental data. Along with the aspect ratio of the orifice and the wall thickness of the cargo tank, the effects of the orifice shapes defined by mathematical figures on the oil outflow were investigated. To consider more realistic situations, the investigation of the ef ect of the crushed iron plate around the damaged part was also included. The numerical results confirmed the change in oil outflow time for various shapes of the damaged part of the oil tank, and discharge coefficients that quantify the viscous effects of those orifice shapes were extracted. To verify the predicted discharge coefficients, they were applied to an oil spill estimation equation. As a result, a good agreement between the CFD and theoretical results was obtained.

• Fire Science and Engineering
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• v.26 no.1
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• pp.113-119
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• 2012

In this research, in order to prevent spread of vertical flame from building exterior fire, A head was developed. The performance standards of Head development complied with NFPA 80A 7.7.4.3 (Recommended Practice for Protection of Buildings Exterior Fire Exposures) and the standards are applied to the discharge pressure was 0.05 MPa and the discharge flow rate was 60 l/min. The head was developed about applied to 0.05 MPa and 65 l/min through the process of the experiment of five times, it is processed from drencher head and used in domestic intended use and structure are quite different. An appropriate distances between the head and the head proved as the experimental results to within 3 m~5 m and it selectively applied to the design is being considered depending on the fire hazard strength.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.1
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• pp.40-50
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• 1994

For an accurate prediction of the temperature field induced by heated water discharged into a shallow crossflow, a two-dimensional near-field numerical model is developed. It is based on a 4-equation turbulence model in which the transport equations for mean of the temperature fluctuation squared and its dissipation rate are added to those of a 2-equation turbulence model which cannot give the information of the thermal time scale ratio. Vertical diffusion is also considered by including buoyancy production and turbulence heat flux terms. The developed model is applied to a steady flow in an open channel with simple geometry and the results are compared with existing experimental data and those of the already established 2-equation turbulence model. Numerical results of the model agree with the experimental data better than those of the 2-equation model. The present model also simulates quite adequately the physical characteristics of thermal discharge in the jet entrainment and stable regions.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.2
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• pp.27-36
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• 2015

The objective of this paper was to quantitatively analyze the effect of concentrated animal feeding operations (CAFO) NPS pollution on a small watershed water quality. Monitoring was conducted from March to October, 2013. Monthly flow rate and selected water quality at each monitoring site were measured during dry days. Rainy day monitoring also was conducted. Modeling was conducted to evaluate the effect of CAFO NPS pollution on the water quality at the watershed outlet. The highest and mean concentration of selected water quality indices during rainy days were higher than those in dry days in general. The highest TN concentration measured at the CAFP pollution discharge point was 237.831 mg/L. The results revealed that the CAFO NPS pollution sources could be equally blamed for the water quality degradation of the stream. However, the effect of the NPS pollution from CAFOs seemed not to be very influential to the watershed water quality at the outlet. SWAT modeling revealed that the TN load was reduced by 18.95 %, 23.39 % and 30.53 % at the watershed outlet if the TN load at the CAFO NPS pollution discharge point reduced by 20 %, 40 % and 60 %, respectively. It was thought that the natural attenuation processes played an important role. The modeling was based only on the assumption of the load reduction and not verified by the monitored data. Therefore, it was suggested that a long term monitoring studies for the evaluation of the impact of CAFO NPS pollution on the watershed water quality be conducted.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.13-19
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• 2004

We have been studied on the high concentration ozonized water production technology which substitute for the SPM wet cleaning solution process as the PR strip process after the photolithography process in the semiconductor and flat panel display manufacturing. In this work, we have developed the surface discharge type ozone generator which has the characteristics of the 12 ［wt%］ ozone concentration at the oxygen gas flow of 0.5［ℓ/min］ oxygen per cell and also developed the high efficiency ozone contactor for the mixing ozone gas with deionized water. As the production test results of the ozonized water, we obtained the ozonized water concentration above 80［ppm］ at the 10［wt%］ ozone gas concentration, and also had a good result of the PR strip rate of 147［nm/min］. at the 70［ppm］ ozonized water.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.46-54
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• 2002

A dielectric pellets bedded parallel plates with a membrane centered have been proposed as an ion separation and collection system in water. and effects of the relative dielectric constant and the applied square wave pulse voltage on the characteristics of ion separation and collection in tap water and NaCl dissolved tap water have been investigated. As a result, electrolyzed water of pH 3.1 and 10.6 were obtained with only tap water at the pulse current of 1.0[A] and flow rate of 0.5[LPM]. And the higher ionized water of pH 2.8 and pH 11.7 ware obtained in 0.1[%wt] NaCl dissolved water. When the dielectric pellets of BaTiO$_3$ having the highest dielectric constant were bedded in the ion separation and collection cell, the ionized water of pH 2.7 and pH 11.7 were obtained with only tap water. And the ionized water of pH 2.4 and pH 12.0 were obtained in 0.1[wt%] NaCl dissolved tap water with the dielectrics pellets bedded ones.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.218.1-218.1
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• 2014

In order to measure the absolute plasma density, various probes are proposed and investigated and microwave probes are widely used for its advantages (Insensitivity to thin non-conducting material deposited by processing plasmas, High reliability, Simple process for determination of plasma density, no complicate assumptions and so forth). There are representative microwave probes such as the cutoff probe, the hairpin probe, the impedance probe, the absorption probe and the plasma transmission probe. These probes utilize the microwave interactions with the plasma-sheath and inserted structure (probe), but frequency range used by each probe and specific mechanisms for determining the plasma density for each probe are different. In the recent studies, behaviors of each microwave probe with respect to the plasma parameters of the plasma density, the pressure (the collision frequency), and the sheath width is abundant and reasonably investigated, whereas relative diagnostic characteristics of the probes by a comparative study is insufficient in spite of importance for comprehensive applications of the probes. However, experimental comparative study suffers from spatially different plasma characteristics in the same discharge chamber, a low-reproducibility of ignited plasma for an uncertainty in external discharge parameters (the power, the pressure, the flow rate and so forth), impossibility of independently control of the density, the pressure, and the sheath width as well as expensive and complicate experimental setup. In this paper, various microwave probes are simulated by finite-different time-domain simulation and the error between the input plasma density in FDTD simulations and the measured that by the unique microwave spectrums of each probe is obtained under possible conditions of plasma density, pressure, and sheath width for general low-temperature plasmas. This result shows that the each probe has an optimum applicable plasma condition and reliability of plasma density measurement using the microwave probes can be improved by the complementary use of each probe.

• Journal of the Korean Electrochemical Society
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• v.5 no.2
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• pp.74-78
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• 2002

Zinc Air battery obtain their energy density advantage over the other batteries by utilizing ambient oxygen as the cathode materials, and reusing cathode as recycled form. And specific capacity of zinc powder is as high as 820 mAh/g. However, if the pore size in cathode is small then the flow rate of air decreased, and as a result of that discharge voltage of batteries becomes low. We focused on resistance and porosity of cathode. So we studied the effects of conducting agents to zinc air batteries performance, capacity, power density, average discharge voltage, resistance. And we also measured porosity of cathode by the ASTM. So we have got optimum contents of conducting agent.

• Archives of Plastic Surgery
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• v.35 no.4
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• pp.393-399
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• 2008

Purpose: Chronic infected wounds sustained over 4 weeks with exposed tendon or bone are difficult challenges to plastic surgeons. Vacuum assisted closure (VAC) device has been well used for the management of chronic wounds diminishing wound edema, reducing bacterial colonization, promoting formation of granulation tissue and local blood flow by negative pressure to wounds. But Commercial ready-made VAC device might have some difficulties to use because of its high expenses and heavy weight. So we modified traditional VAC device with silver dressing materials as topical therapeutic agents for control of superimposed bacterial wound infection such as MRSA, MRSE and peudomonas. Methods: We designed the modified VAC device using wall suction, 400 cc Hemovac and combined slow release silver dressing materials. We compared 5 consecutive patients' data treated by commercial ready-made VAC device(Group A) with 11 consecutive patients' data treated by modified VAC device combined with silver dressing materials(group B) from September 2004 to June 2007. Granulation tissue growth, wound discharge, wound culture and wound dressing expenses were compared between the two groups. Results: In comparison of results, no statistical differences were identified in reducing rate of wound size between group A and B. Wound discharge was significantly decreased in both groups. Modified VAC device with silver dressing materials showed advantages of convenience, cost effectiveness and bacterial reversion. Conclusion: In combination of modified VAC device and silver dressing materials, our results demonstrated the usefulness of managing chronic open wounds superimposed bacterial infection, cost effectiveness compared with traditional VAC device and improvement of patient mobility.