• Journal of the Korean GEO-environmental Society
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• v.12 no.5
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• pp.51-57
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• 2011

Generally, ready-mixed concrete(RMC) gets hardened by time, so the remaining concrete in the drum should be cleaned. But if the RMC waste water generated from this is discharged to soil without any treatment, the strong alkaline elements and heavy metals affect water and ecosystem pollution. Although about 10 to 15% of water used for cleaning in the RMC factory is discharged to soil or river, the concrete report of this affecting soil pollution has not been sufficient. Hence, in this study it was analyzed the extraction of cleaning water from RMC factories all over the country and heavy metal and pH components remaining in soil when this is penetrated to various soils having water permeability. The specimens used for the experiment are weathering soil and soils having different particle size, and it is made to be penetrated to those for 24 hours while fixed thickness of the layer is maintained. Cleaning water is divided into that before deposition treatment(sludge water) and that after deposition treatment(upper water) to be penetrated into soil, and according to the result of penetrating sludge water to soil, Cu and Mn, Fe, and Zn were found to be remained over 23 to 90%. However, it is analyzed that in upper water having deposition treatment, Cu and Mn remain as 60% or more only in weathering soil.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.202-207
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• 2022

The study on electrode degradation of Proton Exchange Membrane Fuel Cell (PEMFC) was mainly studied on the particle growth and active area reduction of Pt on the electrode. The degradation of the electrode catalyst Pt in contact with the membrane affects the deterioration of the polymer membrane, but there are not many studies related to this. In this study, the phenomenon of the deposition of deteriorated Pt inside the polymer membrane during the accelerated electrode catalyst degradation test and its effects were studied. The voltage change (0.6 V ↔ 0.9 V) was repeated up to 30,000 cycles to accelerate the platinum degradation rate. When the voltage change cycle was repeated while oxygen was introduced into the cathode, the amount of Pt deposited inside the film was larger than when nitrogen was introduced. As the number of voltage change cycles increased, the amount of Pt deposited inside the membrane increased, and Pt dissolved in the cathode moved toward the anode, showing a uniform distribution throughout the membrane at 20,000 cycles. In the process of the accelerated electrode catalyst degradation test, the hydrogen crossover current density of the membrane did not change, and it was confirmed that the deposited Pt did not affect the durability of the membrane.

• Toxicological Research
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• v.21 no.2
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• pp.87-98
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• 2005

Human exposure to nano-sized particles (NSP) has increased over the last century with anthropogenic sources, and the rapid development of nanotechnology becomes an another source of such exposure. Information regarding the safety of nanotechnology and its product, nanoparticles, is urgently needed when assuming exposure through inhalation, oral intake, and penetration across skin is ever increasing as growing nanotechnology rapidly. The recent advancement of biokinetic studies with NSP and newer epidemiologic and toxicologic studies with ultrafine particles can be the basis for the nanotoxicology. Some concepts of nanotoxicology can be known from the results of these results. Specific small size of NSP, when inhaled, facilitates deposition by difusional mechanism in all regions of the respiratory tract and uptake into cells, ranscytosis across epithelial and endothelial cells into the blood and lymph circulation to reach target sites. Translocation along axons and dendrites of neuron makes an access to CNS and ganglia. These biokinetics are dependent on NSP surface chemistry. Risk assessments of NSP include appropriate and relevant doses/concentration selections, the increase effects in the organism and the benefits of possible desirable effects. An interdisciplinary team approach is desirable for nanotoxicology research and an appropriate risk assessment.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.1
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• pp.82-87
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• 2011

A study was conducted to determine the relationships between triacylglycerol (TAG) of plasma, very low density lipoprotein (VLDL) and fat deposition in two different breeds of chickens. The VLDL apolipoproteins of both breeds were also characterised. The breeds used were crossbred village chicken (AK) (Sasso crossed) and commercial broiler (CB) (Avian). They were housed in six pens with 30 female and 30 male birds of each breed per pen. Three male and three female birds from each pen were slaughtered and the blood was collected. The VLDL was isolated and sub-fractionated using Fast Protein Liquid Chromatography (FPLC). VLDL TAG of CB was significantly lower than AK. The particle size was negatively correlated with VLDL TAG and positively correlated with abdominal fat. Sub-fraction 2 contained more apo E that will enhance the lipolysis process of the VLDL TAG than subfraction 1. CB had a higher proportion of sub-fraction 2 than AK. The results showed that the proportion of sub-fraction 2 was negatively correlated with VLDL TAG concentration and positively correlated with abdominal fat.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.486-492
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• 2004

CMP (Chemical mechanical polishing) is inevitable process to overcome $0.2{\mu}m$ wire thickness in semiconductor industry. In this study, effect of pressure to separate used CMP slurry into solid and liquid for recycle and reuse by ultrafiltration was investigated. Also, water quality after the ultrafiltration such as turbidity and TDS was evaluated. The material of membrane used in the study was PVDF. The used CMP contained 0.5% of solid content and then concentrated up to 18% by weight. The used CMP can not be concentrated higher than 18% because of viscosity and abrasion of pump. The tested feed pressures were 22.1, 29.4 and 36.8 psi. The results have shown that operating at 36.8 psi has advantages on operation time and total flux. The specific flux showed some variation at 1 to 15 of concentration factor but no difference after 15 of concentration factor. Mass balance of solid at initial stage of the operation showed some unbalance because of deposition of solid on the membrane, which was main reason to reduce flux. Turbidity was very stable at lower than 0.2NTU for 22.1 and 36.8 psi of feed pressure.

• Journal of the Korea Computer Industry Society
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• v.8 no.1
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• pp.17-22
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• 2007

Carbon nanotubes (CNTs) were grown by a thermal chemical vapor deposition (CVD) method, which has been regarded as one of the most promising candidates for the synthesis of CNTs due to low cost and high growth yield. The Ethylene $(C_2H_4)$, hydrogen $(H_2)$ and Argon(Ar) gases were used for the growth of CNTs at $700^{\circ}C$. As a catalyst for CNTs growth, Fe thin film and Iron nitrate and Molybdenyl acetylacetonate solution with alumina nano-particle were prepared on $SiO_2/Si$ substrate. The growth properties of CNTs were analyzed by SEM and AFM.

• Journal of the Korean Ceramic Society
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• v.42 no.6 s.277
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• pp.399-404
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• 2005

Anti-reflection film was coated by using spherical silica nano colloidal particles and fumed silica particles. Silica colloid sol was reserved between two inclined slide glasses by capillary force, and particles were stacked to form a film onto the substrate as the upper glass was sliding. The deposition processes were studied to enhance the wavelength dependency of the light transmittance and to control the effective refractive index of the film. Both of the spherical and fumed silica particles showed an enhancement of $4.0-4.4\%$ in light transmittance by one step coating. The dependence of the transmittance on wavelength was largely improved at the longer wavelength by partial coating of fumed particles on the film of spherical particles. The effective refractive index of the film was controlled by removing latex particles that were co-deposited with silica particles. Using this process the light reflectance from one side of the glass substrate could be reduced from $4.2\%$ to $0.6\%$ although zero reflectance was not achieved due to the agglomeration of the latex particles.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.120-129
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• 2002

New method and device for the on-line measurement of soot concentration in a diesel engine oil are proposed, where the measurement principle is based mainly on attenuated internal total reflection. Various laboratory tests of the detector were performed mainly with carbon black particles of different contamination levels. It was found that the proposed detector could be well used to monitor oil deterioration due to soot contamination. Operational range of the detector was found from 0 to 5 mass percentage of soot content. Test results with water and fuel dilution showed that these effects were not remarkable. However, adsorption of carbon black particles to a measurement surface was considered to be a critical problem in the new detector. Effects of particle deposition onto the interface was experimentally evaluated with the oil temperature and turbulence and discussed throughout this work.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.E1
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• pp.17-24
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• 2001

For the purpose of collecting fog droplets as a function of size a new sampling method was developed in this study. Formation of 100$\pm$10㎛ thickness of polymeric water absorbent film (PWAF) on a nuclepore filter could be successfully realized. Also applicability of particle induced X-ray emission (PIXE) method to the chemical analysis of size-segregated fog droplets collected on PWAF was examined experimentally with synthetic fog droplets generated from a nebulizer. Absorption capacity of S-PAAS polymeric water absorbent shows marked decreases in the range less than 1 wt% and slight decrease between 1 and 3.5 wt% of every salt concentration. Dependency of absorption capacity on pH shows the maximum at pH 7. No apparent peak which can influence the quantitative analysis of elements dissolved and suspended in fog droplets was found at PIXE spectrum of PWAF blank. PWAF kept the original shape without rupture under the PIXE analytical conditions of beam intensity for 10 to 60 nA and irradiation time of 4∼5 min. It should be said that the proposed new technique in the work is helpful to get more detailed information of fog droplets, to clarify the fog formation processes, and to develop a model of acid deposition process.

• Korean Journal of Veterinary Service
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• v.25 no.2
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• pp.127-133
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• 2002

The case reports for clostridium type A enterotoxemia in Formosan deer have rarely been reported. This paper describes a natural case of type A enterotoxemia in farmed Formosan deer in Cheongwon-gun. A dead, male 10-month-old Formosan deer was submitted to Chungbuk Livestock and Veterinary Research Institute, March 24, 2001 and examined. That deer was fed with assorted grain feed, oak leaves, acorn and bean curd. Grossly there was no visible external change. Despite of the carcass being examined within 12 hours of death, there was a quite degree of posonortem decomposition. There was severe hemorrhage in the serosa of abomasum and small intestine. Much blood tinged and watery contents were contained in those organs. Also there were severe swelling of spleen, some red foci in hepatic parenchyma. Microscopically there were severe congestion and hemorrhage in mucosa submucosa, muscular layer, and serosa of abomasum and small intestine. Also spleen and pancreas showed severe Congestion and hemorrhage. There were multifocal hemorrhage with hepatic necrosis in periportal area and focal mononuclear cell deposition in sinusoid. In bacterial culture for small intestine, Cl perfringens was isolated. By toxin typing for the strain, that had $\alpha$ -toxin belonged to type A. In electronmicroscopy for feces, no vims particle was detected. Considering clinical signs, gross lesions, microscopic lesions, bacterial culture, and toxin typing of the isolate, this case was diagnosed as enterotoxemia by Cl perfringens type A.