• Current Photovoltaic Research
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• v.10 no.2
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• pp.49-55
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• 2022

With rapid growth in light-harvesting efficiency from 3.8 to 25.8%, organic-inorganic hybrid perovskite solar cells (PSCs) have attracted great attention as promising photovoltaic devices. However, despite of their outstanding performance, the commercialization of PSCs has been suffered from severe stability issues, especially for UV and humidity: (i) UV irradiation towards PSCs is able to lead UV-induced decomposition of perovskite films or catalytic reactions of charge-transporting layers, and (ii) exposure to surrounding humidity causes irreversible hydration of perovskite layers by the penetration of water molecules, resulting considerable decrease in their power-conversion efficiency (PCE). This review investigates current status of strategies to enhance UV and humidity stability of PSCs in terms of UV-management and moisture protection, respectively. Furthermore, the multifunctional approach to increase long-term stability as well as performance is discussed as advanced research directions for the commercialization of PSCs.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4093-4097
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• 2012

We introduced a new UV-cured resin polymer gel as an electrolyte for dye-sensitized solar cells (DSSCs) that is cured with UV irradiation to form a thin film of UV-cured resin polymer gel in the cells. The gel film was characterized and its potential for use as an electrolyte in DSSCs was investigated. This new UV-cured resin polymer gel was successfully applied as a gel polymer electrolyte in DSSCs overcoming the problems associated with the liquid electrolytes in typical DSSCs. The effect of ${\gamma}$-butylrolactone (GBL) on the long-term stability and photovoltaic performance in DSSCs using this UV-cured resin polymer gel electrolyte was also investigated. The results of the energy conversion efficiency, ionic conductivity and Raman spectra of the UV-cured resin polymer gel electrolyte with the addition of 6 wt % GBL to the UV-cured resin polymer electrolyte showed good long-term stability and photovoltaic performance for the DSSCs with the UV-cured polymer gel electrolyte.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.7-7
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• 2011

Poly(ethylene terephthalate)(PET) is one of the most widely used materials in textile industry. It can have a low cost, silk-like handle, and excellent mechanical properties. Low thermal stability of PET had been a common problem limiting its high temperature application. The polyester have been known to have the disadvantage of degradation under ionized irradiation compared to crosslikable polymers such as polyethylene, polypropylene and polystylene. To improve thermal stability of PET, the PET films were photocrosslinked by UV irradiation. A hydrogen-abstractable photoinitiator was used to photocrosslink of PET by continuous UV irradiation. Photoinitiator addition increased the gel fraction. The photocrosslinking was attributed to the recombination of PET radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of the PET polymer chains by the added photoinitiator. Also the crosslinked PET showed higher thermal stability and mechanical strength with increasing UV energy. Polyester type films such as poly(ethylene naphthalate)(PEN) and poly(butylene terephthalte)(PBT) were also increased the gel fraction and improved thermal stability and mechanical properties by UV irradiation.

• Korean Journal of Oriental Medicine
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• v.1 no.1
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• pp.441-459
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• 1995

To study stability of distilled herbal medicine, we chose changes in UV spectrum, pH, conductivity, and HPLC chromatogram. Aconiti Lateralis preparata Radix and Scutellariae Radix were selected and studied. There ws no consistancy in UV spectrums of preparatons and in duration. The changes in pH and conductivity were not correlated to those in UV spectrums. HPLC chromatograms were also compared each other depending on the preparations. One interesting peak of distilled Aconiti solution was appeared at 40 min retention time which was not identified yet. Ingeneral, UV spectrum, pH, conductivity measurements are pretty poor tool to study stability of herbal medicine although HPLC analysis should be studied further.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.265-269
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• 2010

This paper describes the exfoliation and surface modification of muscovite mica for UV coating formulation. For the exfoliation of the mica, hydrothermal process was used in the presence of lithium nitrate ($LiNO_3$). After the cation exchange with $Li^+$ ions, the surface of the mica was modified with several amphiphilic substances to increase compatibility and storage stability in UV coating formulation. Such a hydrophobic surface modification affected colloidal stability as well as dispersibility of the exfoliated mica in UV coating solution. Anticorrosive property of mica/UV coated steel plates was tested by salt spray test (SST) and compared with sodium montmorillonite ($Na^+$-MMT)/UV coated steel plates.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.19-23
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• 2005

The target of this research is a design of constant and high efficiency driving system for a low pressure UV lamp. An UV lamp system is one of wide range electrical equipments for semiconductor manufacturing and sterilization, etc... It is essential the technique of constant output for high added value device. A design target of driving system for low pressure UV lamp of conversion efficiency is 90[%], UV lamp of output stability within ${\pm}7.5[%]$, and lamp power is over 200[W]. The results meet the target of this study well, and have a benefit of domestic market occupation and enable to export. And if protection circuits were developed, it increases the stability of a electronic ballast for UV lamps.

• Corrosion Science and Technology
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• v.19 no.1
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• pp.16-22
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• 2020

It is important to realize that benzoate was intercalated into hydrotalcite (HTC-Bz) by the co-precipitation method. In this case, acrylic coating with 0.5 wt% HTC-Bz was deposited on carbon steel using the spin coating method. Next, the HTC-Bz structure was characterized by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). In fact, an ultraviolet vision spectroscopy (UV-Vis) was used to determine the benzoate content in HTC-Bz, and the UV absorption ability of HTC-Bz. Using electrochemical techniques, water contact angle measurement, and thermal-gravimetric analysis, we compared the protective properties before and after QUV test, hydrophobicity and the thermal stability of acrylic coating containing HTC-Bz. The obtained results showed that HTC-Bz with a plate-like structure was successfully synthesized; benzoate was intercalated into the interlayer of hydrotalcite with a concentration of 28 wt%. Additionally, it was noted that HTC-Bz has an UV absorption peak at 225 nm. In conclusion, the addition of HTC-Bz enhanced the UV stability, hydrophobicity and the thermal stability of acrylic coating.

• Journal of the Korean Applied Science and Technology
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• v.26 no.2
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• pp.191-198
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• 2009

We have tested the stability of paeoniflorin, a new cosmetic ingredient, extracted from the roots of Paeoniae lactiflora. The stability of aqueous paeoniflorin solution at pH 3, 5 and 7 varied by adding buffer solution was tested at $0^{\circ}C,\;25^{\circ}C,\;40^{\circ}C,\;and\;65^{\circ}C$. The test was performed with or without UV light. The solution of paeoniflorin was stable at pH 3.0, however, the recovery rate of paeoniflorin was 40% at pH 7.0. The stability of paeoniflorin solution was decreased as the pH of paeoniflorin solution was increased by pH 7.0. The effect of storage temperature of paeoniflorin solution shows that the stability of paeoniflorin solution was decreased as the temperature was increased. The stability of paeoniflorin was rather good under UV light than the condition given above $40^{\circ}C$. The stability of paeoniflorin in W/O emulsions shows similar pattern to that of aqueous solution.

• Membrane and Water Treatment
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• v.8 no.3
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• pp.211-223
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• 2017

In this work, an attempt was made to compare the effects of UV irradiation on the intrinsic and separation properties of membranes made of two different polymeric materials, i.e., polyvinylidene fluoride (PVDF) and polyetherimide (PEI). The changes on membrane structural morphologies and chemical characteristics upon UV-A exposure (up to 60 h) were studied by FESEM and FTIR, respectively. It was found that cracks and fractures were detected on the PVDF-based membrane surface when the membrane was exposed directly to UV light for up to 60 h. Furthermore, the mechanical strength and thermal stability of irradiated PVDF-based membrane was reported to decrease with increasing UV exposure time. The PEI membrane surface meanwhile remained almost intact throughout the entire UV irradiation process. Filtration experiments showed that the permeate flux of UV-irradiated PVDF membrane was significantly increased from approximately 11 to $16L/m^2.h$ with increasing UV exposure time from zero to 60 h. Oil rejection meanwhile was decreased from 98 to 85%. For the PEI-based membrane, oil rejection of >97% was recorded and its overall structural integrity was marginally affected throughout the entire UV irradiation process. The findings of this work showed that the PEI-based membrane should be considered as the host for photocatalyts incorporation if the membrane was to be used for UV-assisted wastewater treatment process.

• Journal of Conservation Science
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• v.28 no.3
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• pp.229-233
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• 2012

This research was to evaluate conservational stability of cleaning treatment and color recovery by weak acid treatment on ivory. Before this experiment, had an ivory identification such as black light and schreger angle to find whether it is authentic or not. In wet cleaning treatment on ivory, used polar solvents such as distilled water, acetone, ethyl alcohol and acetic acid which usually used for cleaning ivory and bones. After cleaning took a experiment to evaluate conservational stability in surface observation, calculate weight and color difference. Following these results, these polar solvents were stable on the ivory samples. On the other hand, in weak acid treatment, used samples that were exposed by UV-A, UV-B, UV-C for 1 weeks, to restore its color from changed to original color. After treatment, found tiny cracks and exfoliation on the surface. Moreover, the color changed when it is treated by lemon juice, so, it is impossible to adapt.