• Membrane Journal
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• v.24 no.1
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• pp.31-38
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• 2014

Rainwater harvesting is a process by which rainwater collected from rooftop or other catchment is purified so that the water can be directly or indirectly used by human beings for beneficial uses. As rainwater is increasingly considered for high quality purposes, membranes have gained an important place in rainwater treatment. It has advantages such as the production of high quality water, small footprint, and affordable energy consumption. Nevertheless, membrane fouling is regarded as a serious problem similar to the cases of water treatment and wastewater reclamation. In this study, we applied microfiltration (MF) membranes for rainwater treatment. In addition, a low pressure ultraviolet (UV) process was also use as a pretreatment to control notonly. To quantify the effect of UV on organic matters, both total organic carbon (TOC) and UV absorbance (UVA) were measured. Moreover, the effect of UV pretreatment on membrane fouling was investigated. Experimental results indicated that the pretreatment of membranes using LPUV was effective to control fouling of MF membranes only when the rainwater was contaminated by algae. This was attributed the reduction and modification of organics after UV treatments. It is likely that the UV/MF process is a promising option for water treatment in decentralized water treatment such as micro water grid systems.

• Journal of the Korean Society of Radiology
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• v.4 no.4
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• pp.5-10
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• 2010

The $Ca_2SiO_4$ phosphors doped by La with 0.1 wt%, 0.3 wt%, 0.5 wt%, and 1.0 wt% concentration were prepared by sintering at $1000^{\circ}C$ for 90 minutes in N2 atmosphere. The phosphors were ground in powdered form and were grouped in $100{\mu}m$ size, then the samples had been exposed to low energy X-ray and UV light. The TL glow curves were measured by heating the phosphors at $10^{\circ}C/s$ rate. There was no significantly meaningful correlation between the TL intensity and the doping level. The intensities of the TL peak measured from X-ray irradiated samples doped with 0.1 wt% were relatively strong. The activation energy and the frequency factor were 0.434 ~ 0.516 eV and 0.5 ~ 0.56, respectively. The intensities of the TL peak measured from UV irradiated samples doped with 0.3 wt% were relatively strong. The activation energy and frequency factor were 0.415 ~ 0.477 eV and 0.5 ~ 0.53, respectively. The TL process were found to be the 2nd order for both X-ray and UV irradiation. The TL intensity was increased linearly with the increase of the radiation dose. In summary, the $Ca_2SiO_4 phosphors developed in this study showed good TL characteristics at low energy X-ray and UV light. We believe they will be used as TLDs in near future for personal and environmental radiation detection dosimetry.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.8
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• pp.1273-1279
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• 2009

This study examined the difference in the mechanical properties of cotton fabrics treated with nano silver. Nano silver powder, UV-absorber, and DMDHEU are applied to cotton fabrics. The reagents added in a finishing solution were Triton X-100 and $MgCl_2$ $6H_2O$. The mechanical properties of the fabrics were measured by KES-FB system. From these, the primary hand values were evaluated by the conversion equation (KN-202-DS). The results of this study are summarized as follows. The fabric tensile properties and bending properties are increased by the application of nano silver, DMDHEU, and UV-absorber mixed. The values of tensile properties in the warp direction were significantly lower than those in the weft direction. However, the values of bending properties in the warp direction were higher than those in the weft direction. The differences in the values of compression parameters by nano silver coating were unnoticeable. However, the compression energy and resilience of compression in each fabric was increased by DMDHEU treatment. The SMD values of cotton fabrics are decreased by nano silver, DMDHEU, and UV-absorber mixed treatment.

• Laser Solutions
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• v.12 no.3
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• pp.1-6
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• 2009

This paper describes the method for the fabrication of micro dot array on a plastic mold steel using DPSS (diode pumped solid-states) UV laser and wet etching process. We suggest the process of the ablation of a photoresist (PR) coated on plastic mold steel and wet etching process using solutions of various concentrations of $FeCl_3$, $HNO_3$ in water as etchant. This method makes it possible to fabricate metallic roller mold because the microstructures are directly fabricated on the metal surface. In the range of operating conditions studied, $17\;{\mu}J$ laser pulse energy and 50 ms laser exposure time, an etchant containing 40wt% $FeCl_3$, 5wt% $HNO_3$ and etch time for 45 s gave the $10\;{\mu}m$ of micro dot pattern on plastic mold steel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1091-1096
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• 2003

Ion implantation in polymeric materials can induce dramatic chemical modifications, such as bond breaking, cross linking, formation of new chemical products, which have strong influences on the macroscopic properties of the materials. In this study ion implantation was performed onto polymer, PC(polycarbonate), in order to investigate change of the optical transmittance property focusing ultraviolet ray range(200-400nm). PC was irradiated with N, Ar, Kr, Xe ions at the ion energy of 50keV and the dose range of 5 ${\times}$ 10$\^$15/, 1 ${\times}$ 10$\^$16/, 7${\times}$10$\^$16/ ions/$\textrm{cm}^2$. FT-IR, XPS, UV/Vis transmittance spectroscopy measurement technologies were employed to obtain chemical. structural properties and optical transmittance of irradiated polymer. The original PC(unimplanted) is quite transparent that it has more than 88% transmittance in the range UV-A(320∼400nm), but after ion implantation, surface colors were changed to the dark brown and the transmittance of UV ray decreased for all implantation condition, and the absorption edge was shift to visible range with increasing mass of implanted ion species and dose.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.665-668
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• 1997

We fabricated a number of optical fiber Bragg gratings by varying the UV beam parameters such as the laser energy density, pulse repetition rate and exposing time. The reflectance and the Bragg wavelength shift of the fiber Bragg gratings formed with a KrF excimer laser in real time depend strongly on the UV beam parameters. The index changes in the gratings during the exposing time are well fitted to the well known equations.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.178.1-178.1
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• 2014

본 연구에서는 RF스퍼터링법에 의하여 유리기판에 NiO를 40 nm만큼 증착시킨후, 30분 동안 각각 상온, $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$로 후 열처리 하였다. 박막의 전자적, 광학적 특성은 XPS (X-ray Photoelectron Spectroscopy), REELS (Reflection Electron Energy Loss Spectroscopy)와 UV-Spectrometer를 이용하여 =측정하였고, Hall Effect를 이용하여 전기적 특성을 측정하였다. XPS측정결과, $400^{\circ}C$ 후 열처리 한 NiO박막은 NiO 결합인 Ni2+가 줄어 들면서 금속 결합인 Ni0가 증가하면, 상온에서 띠틈이 4.0eV, 3.4eV로 줄어드는 것을 REELS로 확인 했다. 이 값은 UV-Spectrometer를 이용한 광학적 띠틈과 같음을 보였다. Hall Effect측정 결과 $400^{\circ}C$ 후 열처리한 샘플에서 P-type에서 N-type으로 바뀜을 보였으며, 비저항이 낮아지는 경향을 보였다. UV-Spectrometer를 이용한 광학적 특성을 측정해본 결과, 가시광선영역인 380 nm~780 nm에서의 투과율이 75%이상으로 투명전자소자로의 응용이 가능하다는 것을 보여 주었다.

• Textile Coloration and Finishing
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• v.24 no.2
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• pp.97-105
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• 2012

Compared with conventional adsorption-based coloration, the photoreactions of dyes such as photo-copolymerization and photo-crosslinking under UV irradiation can be employed for the coloration of textiles, which can be carried out without salt addition at room temperature. C.I. Reactive Black 5, a homo-bifunctional reactive dye containing two sulfatoethylsulfone groups, is used as a photo-reactive dye for wool fibers. Upon UV irradiation, the photo-reactive dye was grafted onto wool fabrics without photoinitiators. Since the disulfide bonds in the cystine residues of wool can be easily photodecomposed to active thiyl radicals which initiate the polymerization, the dye can be polymerized to an oligomeric dye of a degree of polymerization of 12 or more. The grafted fabrics reached a grafting yield of 2.3% o.w.f. and a color yield (K/S) of 18.2 by the photografting of an aqueous dye concentration of 9% using a UV energy of 25J/$cm^2$. Furthermore, the photochemically dyed wool fabric showed higher colorfastness properties to light, laundering and rubbing comparable to conventional reactive dyeing.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.97-98
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• 1998

1. Introduction : Polypropylene(PP) membrane is widely used in the field of microfiltration and ultrafiltration. However, the hydrophobicity of PP causes the adsorption of hydrophobic and amphoteric solutes in the feed. Surface modification techniques of membrane through the treatment of hydrophilizing agents, coating of hydrophilic compounds, UV, plasma and high energy irradiation, etc. can have a great effect on propensities to prevent the protein from staining membranes. Among them, the modification to hydophilize membrane surface using UV is very simple and effective. Recently many studies for more effective surface modification have been conducted. Iwata et al. prepared membranes by grafting polyethylene glycol diacrylate macromer(PEGDA) onto polysulfone with plasma using a glow discharge reactor which prevent the oil from staining the membrane. The primary mechanism contributing to the membranes is preventing the oil from directly contacting the surface of the membrane as the PEGDA chains dissolved into emulsion. To evaluate their feasibility for use as a anti-fouling separation membrane, we prepared hydrophilic membranes by UV irradiation method and investigated their characteristics.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.931-937
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• 2012

In this study, we assessed environmental impacts of compound humidifiers using environmental life cycle assessment and presented the ways to improvements in energy consumption of them. We found eco-design parameters and $CO_2$-eq emissions in each stage of raw material acquisition, manufacturing, transportation, use and disuse in life cycle of the compound humidifiers. The highest $CO_2$ emission is found to be in the stage of use among all stages of life cycle, which is mainly due to power consumption in thermal heating of heating coil for sterilization during humidification. The power consumption and $CO_2$ emission in the stage of use can be reduced to 1/4 and 1/3 at the highest estimate through improvement of sterilization method, respectively. We suggested the replacement of conventional thermal heating coil by ultra violet light-emitting diodes (UV-LED) for sterilization and then presented the experimental results on the sterilization effects of UV-LEDs.