• Journal of Environmental Health Sciences
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• v.35 no.6
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• pp.500-509
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• 2009

Passive samplers have been used for many years for the sampling of organic vapors in work environment atmospheres. Currently, all passive samplers used in domestic occupational monitoring are foreign products. This study was performed to evaluate variable parameters for the development of passive organic samplers, which include the geometry of the device and diffusive length for the sampler design. Four prototype diffusive lengths; A-1(4.5 mm), A-2(7.0 mm), A-3(9.5 mm), A-4(12.0 mm) were tested for adsorption performances to a chemical mixture (benzene, toluene, trichloroethylene, and n-hexane) according to the US-OSHA's evaluation protocol. A dynamic vapor exposure chamber developed and verified by related research was used for this study. The results of study are as follows. The results in terms of sampling rate and recommended sampling time test indicate that the most suitable model was A-3 (9.5 mm diffusive lengths on both sides) for passive sampler design in time weighted average (TWA) assessment. Sampling rates of this A-3 model were 45.8, 41.5, 41.4, and 40.3 ml/min for benzene, toluene, trichloroethylene, and n-hexane, respectively. The A-3 models were tested on reverse diffusion and conditions of low humidity air (35% RH) and low concentrations (0.2 times of TLV). These conditions had no affect on the diffusion capacity of samplers. In conclusion, the most suitable design parameters of passive sampler are: 1) Geometry and structure - 25 mm diameter and 490 $mm^2$ cross sectional area of diffusion face with cylindrical form of two-sided opposite diffusion direction; 2) Diffusive length - 9.5 mm in both faces; 3) Amount of adsorbent - 300 mg of coconut shell charcoal; 4) Wind screen - using nylon net filters (11 ${\mu}m$ pore size).

• Fashion & Textile Research Journal
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• v.22 no.4
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• pp.534-539
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• 2020

Experimental research is needed to provide information on the removal of bloodstains since washing clothes contaminated with blood is necessary for medical related fields (such as ambulance workers and doctors) as well as for women of childbearing age. This study investigated efficient washing conditions for the removal of bloodstains with a focus on washing temperature, fiber type and blood ageing time. Polyester/cotton fabric showed the highest detergency from among three fabrics that were influenced by the composition of the fiber and the structure of the yarn and fabric. When examining the effect of detergent, it was concluded that the alkalinity over pH 10 was essential to remove bloodstains and that auxiliary agents such as soil antiredeposition agents and bleach had a significant effect on the removal of bloodstains. Washing temperature showed the highest detergency at 20℃ due to the activity of the enzyme without the denaturalization of blood. Blood-ageing influenced detergency by inducing changes in the adsorption area and chemical bond. A combination of methods such as quick removal after contamination, use of alkaline detergents including soil antiredeposition agents and bleach, and low-temperature washing could help remove bloodstains.

• Membrane Journal
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• v.16 no.1
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• pp.1-8
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• 2006

Nanofiber is a broad phrase generally referring to a fiber with diameter less than 1 micron. Various polymers have been successfully electrospun into nanofibers in recent years. These nanofibers, due to their high surface area and porosity, have a great potential for use as filter medium, adsorption layers in protective clothing, etc. Nanofiber filters will enable new levels of filtration performance in the field of air filtration. In particular, nanofibers provide marked increases in filtration efficiency at relatively small pressure drop in permeability. Therefore, nanofiber filters could be substituted for conventional filter market due to the easy application of process and the possibility of coating to micron-sized non-woven sheets. This review is discussed on the trend of researche and development related to nanofiber filter including future marketability.

• Membrane Journal
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• v.19 no.4
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• pp.333-340
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• 2009

This paper is designed with the purpose of improving the efficiency of the sulfonic acid ion exchange membranes by radiation induced graft polymerization. It has been shown that the porous hollow fiber membranes could cause permeability blocking between pores and ion exchanged graft chains. Addition of crosslinker such as N-ethylene glycol dimethacrylate will permit to increase the permeation flux. In this research, the ethylene glycol dimethacrylate (EDMA) and diethylene glycol dimethacrylate (DDMA) with different length are used as crosslinkers. The ion exchanged cross-linked membrane (EDMA, DDMA) containing sulfonic acid group by radiation induced grafted polymerization are sn died for adsorb metal ions (Pb). It has been shown that adsorbed metal ions ($Pb^{2+}$) for the EDMA and DDMA membranes with the density of sulfonic acid groups, 1.40 mmol/g and 2.14 mmol/g, respectively are 13.82 mg/g, 17.37 mg/g, accordingly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.166-169
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• 2003

In this study, we evaluated the characteristics by the addition of 3 different kinds of nonionic surfactant to improve the dispersion stability of slurries. Slurry stability is an issue in any industry in which settling of particles can result in poor performance. So we observed the variation of particle size and settling rate when the concentration and addition time of surfactant are changed. When the surfactant is added after milling process, the particle size and pH became low. It is supposed that the particle agglomeration was disturbed by adsorption of surfactant on alumina abrasive. The settling rate was relatively stable when nonionic surfactant is added about 0.1~1.0 wt%. When molecular weight(MW) is too small like Brij 35, it was appeared low effect on dispersion stability. Because it can't prevent coagulation and subsequent settling with too small MW. The proper quality of MW for slurry stability was presented about 500,000. Consequently, the addition of nonionic surfactant to alumina slurry has been shown to have very good effect on slurry stabilization. If we apply this results to copper CMP process, it is thought that we will be able to obtain better yield.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.1
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• pp.43-48
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• 2000

Upon the Preparation of activated carbon fiber(ACF) using chemical activation method and vapour activation method, the fiber obtained from the vapour activation method shows excellent surface Properties. The preparation of antibacterial activated carbon fiber was tried to open the new areas in application of carbon materials. The BET specific surface area and the average pore radius of the antibacterial ACFs were in the range of 844.27~1575.6 $cm^2$/g and 10.6~12.9 (equation omitted), respectively. From the adsorption studies on the antibacterial ACFs, typical Type I isotherms were obtained. And, from the SEM morphology results, it was observed that the surface of ACFs was partially coated by antibacterial materials after the treatment. Finally, from the antibacterial effects of antibacteral ACFs against E. coli, excellent antibacterial activity was shown. Concerning the above results, antibacterial ACFs can have wide application in the areas of sterilization, anti-fragrant. anti-insects.

• Polymer(Korea)
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• v.24 no.3
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• pp.299-305
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• 2000

In order to increase the thermal stability at high temperatures, new hybrid ceramic percursors were synthesized by chemical modification of polycarbosilane (PCS). The structure of hybrid ceramic percursors were investigated by using FT-IR and $^1$H-NMR spectrometers. The syntheses of hybrid ceramic precursors were confirmed by monitoring the change of the adsorption peaks appearing at 0893, 1092, 609 $cm^{-1}$ / on the FT-IR spectra, and also by the presence of peaks at 3.8, 2.0, 0.6 ppm on the $^1$H-NMR spectra. The conversion of hybrid ceramic percursor was around 74 and 10 wt% higher than that of the pure PCS. After the heat-treatment at 150$0^{\circ}C$, the crystalline peaks for $\beta$-SiC were observed at 2$\theta$=35.7, 42.2, 61.0$^{\circ}$ on the X-ray powder diffractogram. It showed the conversion of hybrid ceramic percursor to crystalline $\beta$-SiC.

• Polymer(Korea)
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• v.33 no.1
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• pp.84-90
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• 2009

Nitinol alloy (TiNi) has been widely used in vascular stents. To improve the blood compatibility of Nitinol alloy, its surface was chemically modified in this study. Nitinol was first coated with gold, then chemisorbed with L-cysteine (C/N), and followed by grafting of zwitter ionic poly(ethylene glycol) (PEG) (PEG-$N^+-SO_3{^-}$) to produce TiNi-C/N-PEG-N-S. The zwitter ionic PEG grafted on the Nitinol surface was identified by ATR-FTIR, ESCA and SEM. The hydrophilized surface was proven by the decrease of water contact angle. In addition, from the blood compatibility tests such as protein adsorption, platelet adhesion, and blood coagulation time, the surface-modified TiNi alloy exhibited a better blood compatibility as compared to the untreated Nitinol control. These results indicated a feasibility of synergistic effect of hydrophilic PEG and antithrombotic zwitter ion.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.77.2-77.2
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• 2013

In this talk, I will briefly review recent results of my group related to application of atomic layer deposition (ALD) for fabricating environmental catalysts and organic solar cells. ALD was used for preparing thin films of TiO2 and NiO on mesporous silica with a mean pore size of 15 nm. Upon depositing TiO2 thin films of TiO2 using ALD, the mesoporous structure of the silica substrate was preserved to some extent. We show that efficiency for removing toluene by adsorption and catalytic oxidation is dependent of mean thickness of TiO2 deposited on silica, i.e., fine tuning of the thickness of thin film using ALD can be beneficial for preparing high-performing adsorbents and oxidation catalysts of volatile organic compound. NiO/silica system prepared by ALD was used for catalysts of chemical conversion of CO2. Here, NiO nanoparticles are well dispersed on silica and confiend in the pore, showing high catalytic activity and stability at 800oC for CO2 reforming of methane reaction. We also used ALD for surface modulation of buffer layers of organic solar cell. TiO2 and ZnO thin films were deposited on wet-chemically prepared ZnO ripple structures, and thin films with mean thickness of ~2 nm showed highest power conversion efficiency of organic solar cell. Moreover, performance of ALD-prepared organic solar cells were shown to be more stable than those without ALD. Thin films of oxides deposited on ZnO ripple buffer layer could heal defect sites of ZnO, which can act as recombination center of electrons and holes.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.218-222
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• 2017

This study was conducted to remove $NO_x$, which is the main cause of fine dust and air pollution as well as acid rain. $NO_x$ was tested using 3% NO (diluted in He) as a simulated gas. Experiments were sequentially carried out by oxidizing NO to $NO_2$ and absorbing $NO_2$. Especially, we focused on the changes of NO oxidation according to both oxidant ($NaClO_2$) concentration change (1~10 M) and oxidant pH change (pH = 1~5) by adding HCl. In addition, we tried to suggest a method to improve $NO_2$ absorption by conducting $NO_2$ reduction reaction with reducing agent (NaOH) concentration (40~60%). It was found that NO removal efficiency increased as both concentration of oxidant and flow rate of NO gas increased, and NO decreased more effectively as the pH of hydrochloric acid added to the oxidant was lower. The $NO_2$ adsorption was also better with increasing NaOH concentration, but the NO removal efficiency was ~20% lower than that of the selective NO reduction. Indeed, this experimental method is expected to be a new method that can be applied to the capture and removal of fine dust caused by air pollution because it is a method that can easily remove NO gas by a simple device without expensive giant equipment.