• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.6
• /
• pp.640-647
• /
• 2006

It is difficult to treat wastewater involved in heavy metal in electroplating industry. Recently, many industries adopt the clean technology to prevent production of pollutant in the process or reuse after the appropriate pollutant treatment. In this study, we estimate the ability of recovery of nickel and the efficiency using lab-scale ion exchange and electrodialysis process with electroplating industry wastewater. In the ion exchange experiments with 5 types of resin, the result showed that S 1467(gel-type strong acidic cation exchange resin) has the highest exchange capacity. And it showed that the 4 N HCl has the highest in regeneration efficiency and maximum concentration in the regeneration experiments with various kinds md concentration of the regenerant. During the electrodialysis experiments, we varied the current density, the concentration of electrode rinse solution, the flow rate of concentrate and electrode rinse solution in order to find the optimum operating condition. As a result, we obtained $250A/m^2$ of current density, 2 N $H_2SO_4$ of concentration of electrode rinse solution, 30 mL/min of flow rate of concentrate and electrode rinse solution as the best operating conditions. We performed the scale-up experiments on the basis of ion exchange and electrodialysis experiments. And we obtained the experimental result that exchange capacity of S 1467 was 1.88 eq/L resin, and regeneration efficiency was 93.7% in the ion exchange scale-up experiment, we also got the result that concentration and dilution efficiency increased, and current efficiency kept constant in the scale-up experiments.

• Analytical Science and Technology
• /
• v.28 no.5
• /
• pp.309-316
• /
• 2015

The analytical method of lead in plasma by ICP-MS was validated after securing environment within class 1,000 classification. We tested specificity and accuracy of within-run and between-run. According to measurement of the amount of suspended particulates in a clean room, 0.3~62 particles were detected in 0.3 µm size while 0.0~28.3 particles were observed in 0.5 µm size. Total suspended particulates met required environment with up to 90.3 particles. The MDL (Method detection limit) of the sample which has been fabricated using fetal bovine serum (FBS) blank was 1.77 ng/L, and LOQ (Limit of quantification) was 5.55 ng/L. The slope, intercept and correlation coefficient of the calibration curve were y=1.09×10⁻³x+4.88×10⁻² and r=0.9999, which showed good correlation. The specificity, within-run and between-run accuracy satisfied the standard at more than 50 ng/L. The average lead concentration in plasma of the general people, current workers and retired workers was 55.4 ng/L, 440 ng/L, and 132 ng/L.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.4
• /
• pp.281-288
• /
• 2011

Recently, researches that a variety of contaminants in water are removed by sonolysis technology with oxidation and pyrolysis process from cavitation were conducted. However, there are few studies for sonochemical treatment by a pilot-scale ultrasound system. This research focused on developing pilot-scale ultrasound systems, which could be an continuously effective treatment for a large volumes of contaminants, and demonstrating the feasibility of utilizing these systems to remove naphthalene from groundwater. V-120 type reactor was found to be 1.4~2.2 times higher effective than the normal type. A total of three different pilot scale's systems consisted of installing effluent and irrigation water in order to be a continuos system, including supplemental additives, and applying a V-120 type reactor and a external cooling cycle system. Naphthalene levels treated by three systems were lower than a recommended guideline of naphthalene for drinking water in EPA. Especially, the naphthalene removal efficiencies of PS1 and PS2 systems were over 97%. The pilot-scale continuous ultrasound clean-up system delivered over 84~95% naphthalene removal efficiency for treatment of 10~20 liter of groundwater. In addition, the ultrasound system could be successfully applied to the conditions of artificial and genuine groundwater contaminated with naphthalene.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.8
• /
• pp.817-822
• /
• 2008

In this study, the photocatalytic degradation of methylene blue in TiO$_2$ particles-dispersed water solution was carried out by irradiating microwave and UV light simultaneously. A microwave-discharged electrodeless UV lamp was developed to use microwave and UV simultaneously for photocatalytic reactions. The results of photocatalytic degradation of methylene blue showed that the decomposition rate increased with the microwave intensity, the circulating fluid velocity, and the amount of TiO$_2$ particles and auxiliary oxidizing agents added. Especially, the rate constant of H$_2$O$_2$-added photocatalytic reaction increased about three times from 0.0075 min$^{-1}$ to 0.0250 min$^{-1}$ when microwave was additionally irradiated. This study demonstrates that the microwave irradiation can play a very important role in photocatalytic degradation using peroxides although it is not easy to quantitatively assess the effect of microwave on photocatalytic reactions from the experimental data of this study.

• Membrane Journal
• /
• v.15 no.2
• /
• pp.114-120
• /
• 2005

The purpose of this study is to obtain practical information about membrane coupled $ A_2O$ system for muncipal wastewater treatment. A flat-plate microfiltration (MF) module with a pore size $0.25\;{\mu}m$ was submerged into the aeration basin and treated water was filtrated through the membrane by continuous suction with low pressure. The system was operated with synthetic wastewater to find operational parameters of internal recycle ratio and maximum MLSS showing best water quality and long-term stability. The internal recycle was defined as type 1 for aerobic to anoxic tank and type 2 for anoxic to anaerobic tank, respectively When the flux was maintained at $0.015\;m^3/m^2/hr$ (15 LMH) with 2Q type 1 internal recycle ratio, the optimal operational setting were 10 internal recycle ratio for type 2 and maximum MLSS of 11,000 mg/L among tested conditions. At this condition, removal efficiencies of BOD, CODcr, T-N and T-P showed $97.3\%,\;94.2\%,\;64.0\%,\;63.0\%$, respectively.

• Journal of the Korean Ceramic Society
• /
• v.39 no.6
• /
• pp.610-615
• /
• 2002

Phase formation and proton conduction of L $a_{0.6}$B $a_{0.4}$I $n_{1-y}$ $M_{y}$ $O_{3-{\delta}}$(M=G $a^{3+}$, S $c^{3+}$, Y $b^{3+}$) system were studied. A cubic perovskite structure with a single phase was formed in all of the compositions of this work except for the composition off=G $a^{3+}$ with y=0.5, viz,L $a_{0.6}$B $a_{0.4}$I $n_{1-y}$G $a_{0.5}$ $O_{3-{\delta}}$ For the compositions of M=S $c^{3+}$and Y $b^{3+}$with y=0.25, proton conduction occurred in wet $N_2$ atmosphere(P $h_{H_2O}$=6.1hPa).X>/=6.1hPa).Pa).

• Journal of Korean Society of Forest Science
• /
• v.101 no.2
• /
• pp.175-184
• /
• 2012

This study was conducted to develop new mattress systems with vegetation base materials for protecting stream bank and rapid rehabilitation. Vegetation base materials are primarily compounded with fine soil, organic composts and peat moss as plant fibers, a water retainer and a soil improver. Peat moss can usually provide necessary natural fibers and organic materials in soil. Especially, peat moss can absorb up to 25 times its own weight in water and is therefore valued as a water retainer to prevent drying effect of vegetation base materials which can harm the growth of vegetation in mattresses. Normally mattress systems resist the lateral earth pressures or stream power by their own weight. Therefore, filled materials must have suitable weight, compressive strength and durability to resist the loading, as well as the effects of water and weathering. In this project, 100 to 200-mm clean, hard stones were basically specified, and about 50-mm rubbles were also used. Test application of new mattress system carried out in the stream bank of a small stream in the Gwangreung experimental forest, belonging to Korea Forest Research Institute (KFRI) in December 16th, 2006. As a result of the monitoring of vegetation coverage of test application plots (each plot size is 4 by 2 m), the coverage of all plots reached 100% in the end of May, 2007 (approximately 50 days passed after the first gemination of vegetation). The coverage of the plots using big hard stones and organic composts and the plots containing peat moss increased more rapidly. The results show that peat moss is effective to retain soil moisture and establish more sound environment for vegetation gemination.

• Korean Chemical Engineering Research
• /
• v.54 no.6
• /
• pp.854-862
• /
• 2016

As the demand for a clean energy to replace fossil fuel being depleted increases, hydrogen energy is considered as a promising candidate for future energy source. Water electrolysis which produces hydrogen has high energy efficiency and stability but still has a large overpotential for oxygen evolution reaction (OER). In this study, $Co_3O_4$ catalysts with different morphology were prepared by spray pyrolysis from solutions which contain Co precursor and various organic additives (urea, sucrose, and citric acid), followed by post heat treatment. For the catalysts synthesized, X-ray diffraction (XRD) measurements were performed to identify their crystal structure. Morphology and surface shape of the catalysts were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Surface area and pore volume were examined by nitrogen adsortpion & desorption tests and X-ray photoelectron spectroscopy (XPS) was conducted to confirm nitrogen doping. Linear sweep voltammetry (LSV) was carried out to investigate OER activity of $Co_3O_4$ catalysts. As a result, bare-$Co_3O_4$ which has high surface area and small particle size determined by spray pyrolysis showed high activity toward OER.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.45 no.3
• /
• pp.9-20
• /
• 2017

Camp Page, which has been located in front of Chuncheon Station for about 50 years since 1958, recently opened to the public. Chuncheon City is currently struggling to construct a park on this site due to an uncertainty of general plans and financial difficulties. Accordingly, this research conducted a cognitive survey about site usage with Camp Page users in order to clarify directions for efficient establishment of parks within the former military base. The course of research includes analytical methods such as a survey targeting Chuncheon citizens and tourists both in the field and online, a frequency analysis of 1,360 index samples, a cross analysis and t-test. As a result, firstly, Chuncheon citizens recognized the image of Chuncheon as a city with a fresh, clean lakeshore whereas tourists think of it as a city for sightseeing and leisure. Hence, it was justifiable to conclude that the city should organize various programs for people to enjoy leisure activities while at the same time protecting the environment. Second, the awareness of tourists about Camp Page was relatively low and both citizens and tourists recognize that it was not sufficient enough for enjoyment of free time. The majority answered "space for culture and art and for experiencing the natural environment" when asked about the direction of space creation at Camp Page, which indicates that the site will need to be available both for cultural art and nature experiences. Lastly, it was thought that the direction of developing leisure facilities in Chuncheon city should include the improvement of worn out installations and developing chain products among programs. This research will be able to use fundamental data for the efficient utilization of the returned U.S. military camps that are constantly merging.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.1
• /
• pp.31-37
• /
• 2016

Co-firing of biomass with coal is a promising combustion technology in a coal-fired power plant. However, it still requires verifications to apply co-firing in an actual boiler. In this study, data from the Thermogravimetric analyzer(TGA) and Drop tube furnace(DTF) were used to obtain the combustion characteristics of biomass when co-firing with coal. The combustion characteristics were verified using experimental results including reactivity from the TGA and Unburned carbon(UBC) data from the DTF. The experiment also analyzed with the variation of the biomass blending ratio and biomass particle size. It was determined that increasing the biomass blending ratio resulted in incomplete chemical reactions due to insufficient oxygen levels because of the rapid initial combustion characteristics of the biomass. Thus, the optimum blending condition of the biomass based on the results of this study was found to be 5 while oxygen enrichment reduced the increase of UBC that occurred during combustion of blended biomass and coal.