• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.652-656
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• 2009

A cylindrical ultraviolet (UV) sterilization system was developed for decreasing microorganisms in takju. The takju was passed through 110 strips of honeycomb-type teflon tubing with 9 UV lamps (1,395 W) set between the teflon tubes. Thus, during passage, the takju was effectively exposed to the UV rays without loss. In terms of the overall quality aspects of the takju, the optimum sterilization condition was set for 4 min at 2 L/min. A 2-3 log cycle decrease in viable cell numbers of total bacteria and fungi was observed at this operating condition. Quality changes in the UV-sterilized takju were examined via UV irradiation of samples followed by storage at 30oC for 8 days. To evaluate the quality changes, pH, amino nitrogen content, acidity, reducing sugar content, and viable cell numbers of total bacteria and fungi were measured. Increases in pH, acidity, and amino nitrogen content were observed in both the takju control and UV sterilized takju with increasing storage time. However, reducing sugar content was decreased in both samples. The L, a, and b values of the control takju and UV sterilized takju showed similar trends over the storage period. Viable cell numbers of fungi did not change in the control or UV sterilized takju during storage, showing approximately $10^8\;CFU/mL$ and $10^4-10^5\;CFU/mL$, respectively. In addition, viable cell numbers of total bacteria remained lower in the UV sterilized takju over 4 days compared to the non-sterilized takju.

• Journal of Conservation Science
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• v.32 no.3
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• pp.377-384
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• 2016

There are physical and chemical method for removement of a lacquered layer existing on the surface when gilding an iron Buddha, these caused environmental pollution by surface degradation and is very noxious for conservation scientist's health. Thus, on this study, we conducted a lacquered layer removement experiments using Nd:YAG Laser which is contactless and eco-friendly. Specimens were made by polishing $5{\times}5$ size of iron(99.9%) specimens surfaces evenly and by differing of number of coating of unrefined lacquer, so there were thickness differences of $10{\mu}m$, $20{\mu}m$, and $30{\mu}m$. The laser machine used in this study was Nd:YAG Laser, and we used two wavelength modes; 1064 nm(160~180 mJ) for infrared light region and 532 nm(50~350 mJ) for ultraviolet light region. The experiment done by investigating the transition of specimens' surfaces with laser wavelength, energy, and numbers of investigation. The remain amount of lacquered layer surfaces before/after laser irradiation was investigated by stereoscopic microscope, observation by SEM, Non-contact Surface Roughness Measurement Device, and FT-IR etc. As a result of each analysis, we could verify the thickness of $10{\mu}m$, $20{\mu}m$ of lacquered layer removed without surface degradation when using 1064 nm wavelength with $1.0J/cm^2$ density. We could find out that Nd:YAG Laser is effective for removing remained lacquered layers when gilding an iron Buddha. In the future, when not only the metal has made various studies also wood lacquered furniture or the like, it seems to be utilized to remove the lacquer without surface damage.

• Journal of Conservation Science
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• v.26 no.1
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• pp.61-67
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• 2010

After selecting five types of adhesive epoxy resin for metallic cultural assets such as $Araldite^{(R)}$ rapid type, $Devcon^{(R)}$, $Araldite^{(R)}$ SV427+HV427, $CDK^{(R)}$520, $Araldite^{(R)}$ AW106+HV953 which had already been studied, this paper approached more closely the problem of yellowing and the signal of aging with time passing by connecting the problems with the safety of metallic cultural assets. The change of physical properties according to the change of state of epoxy adhesives was investigated through the change of flexural strength and the change of surface hardness by artificially providing the possible environmental change factors such as ultra-violet ray, and acid base, and how the epoxy chemically changes in its ingredients by the environment was analyzed through FT-IR. As a result of the experiment, for the most part of adhesives brought about the physical change of flexural strength, the change of surface hardness, and the chemical change of chemical ingredients as the product of alcohol, which were respectively different according to the time of ultraviolet irradiation, and acid base change. Under most of the conditions, SV427+HV427 and $CDK^{(R)}$520 were fairly stabilized under each condition of weatherability, but it seems that they should be refrained from being applied in case that the area to restore is thin and wide because the degree of flexural strength of themselves is low. Also, it is found that the preservation environment is very important not only for artifacts but also for the preservation of resins sused for preservation treatment.

• Journal of Conservation Science
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• v.35 no.5
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• pp.480-493
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• 2019

In this study, the method for processing glue and glue-alum sizing from the dancheong ground treatment was evaluated with respect to weather resistance, and its effect on the conservation of dancheong was analyzed. Viscosity and pH of the glue and glue-alum specimen were measured and classified into three categories(none layer, glue layer, and glue-alum layer), which were further classified according to low concentration(four times for 2%) and high concentration(once for 10%). The base layer formation was subsequently classified into three categories based on pigment adoption, namely, Noerok(celadonite), Seokganju(terra rossa), and Jangdan(red lead). The completed specimen was subjected to a changing-environment experiment for evaluating weather resistance and observing the surface. Color variations were analyzed before and after the experiment. The results indicate that glue-alum sizing comprising 5% alum or 7% alum has strong acidity that can affect the life of dancheong, and the high level of 7% alum makes it difficult to create a solid coating layer. After ultraviolet irradiation, the specimen with 7% alum changes its color to yellow. Furthermore, after moisture absorption and drying, cracks can be observed on the entire specimen surface that corroborate the physical change. Additionally, gas-based corrosion causes marginal surface changes. Hence, the formation of a stable coating layer can be achieved by incorporating a low concentration glue solution that is almost neutral, and the application of glue-alum sizing having 2% concentration can aid in the conservation of dancheong.

• Clean Technology
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• v.26 no.1
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• pp.7-12
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• 2020

Ti-SBA-15 catalysts doped with lanthanide ions (Ln/Ti-SBA-15) were successfully synthesized using conventional hydrothermal method. In addition, they were characterized by XRD, FT-IR, DRS, BET, and PL. The activity of these materials on the photocatalytic decomposition of methylene blue under ultraviolet light irradiation was also examined. Ti-SBA-15 catalysts doped with various lanthanide ions maintained their mesoporous structure. The pore size and pore volume of Ln/Ti-SBA-15 materials decreased but their surface area increased upon the doping of lanthanide ion. Ln/Ti-SBA-15 materials exhibited the type IV nitrogen isotherm with desorption hysteresis loop type H2, which was characteristic of mesoporous materials. The size of hysteresis increased in the doping of lanthanide ions on Ti-SBA-15 material. There was no absorption in the visible region (> 400 nm) regardless of the doping of lanthanide ions to TiO₂ particles, while the broad bands at 220 nm appeared at the Ln/Ti-SBA-15 samples, indicating the framework incorporation of titanium into SBA-15. 1 mol% Pr/ Ti-SBA-15 catalysts showed the highest photocatalytic activity on the decomposition of methylene blue but the Ti-SBA-15 catalysts doped with Eu, Er, and Nd ions showed lower activity compared to pure Ti-SBA-15 catalyst. The PL peaks appeared at about 410 nm at all catalysts while the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of methylene blue.

• Transactions on Electrical and Electronic Materials
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• v.8 no.3
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• pp.135-138
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• 2007

In this study, we investigated the electro-optical (EO) characteristic of fringe-field switching (FFS) mode cell by the two kinds of ultraviolet (UV) alignment method on the organic thin film (polyimide: PI). The suitable organic layers for FFS cell and the aligning capabilities of nematic liquid crystal (NLC) using the in-situ photoalignment method were studied; Disclination is observed after conventional photoalignment method for 1h, and in-situ photoalignment method for 1h. Monodomain alignment of the NLC can be observed via insitu photo alignment method for 2 h and 3 h. It is considered that NLC alignment is due to photo-depolymerization of the polymer with oblique non-polarized UV irradiation on PI surface. An unstable V-T curve of UV-aligned FFS-LCD with conventional photoalignment method can be achieved. However, a stable V-T curve of UV-aligned FFS-LCD with in-situ photoalignment method (1 h), and V-T curve of UV-aligned FFS-LCD with in-situ photo alignment method was much stable comparing with that of other UV-aligned FFSLCD's. As a result, more stable EO performance of UV-aligned FFS-LCD with in-situ photoalignment method for 3h is obtained than that of the other UV-aligned FFS-LCD's.

• Journal of Korean Society on Water Environment
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• v.32 no.4
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• pp.357-366
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• 2016

N-nitrosamines are a class of carcinogenic chemicals that can pose significant hazards to the human life. Ultraviolet (UV) light irradiation is considered as one of the effective methods to reduce N-nitrosamines in the aqueous phase. This study aimed to investigate the pH influence on UV photodegradation of N-nitrosamines (i.e., N-nitrosodibutylamine (NDBA) and N-nitrosopyrrolidine (NPYR)) closely related to water treatment. Photodegradation rate constants of NDBA and NPYR remained between 3.26×10^-2 L/W-min to 5.08×10^-3 L/W-min and 1.14×10^-2 L/W-min to 2.80×10^-3 L/W-min at pH2-10, respectively. This study also focused on the formation of oxidized products (i.e., primarily NO^2- and NO^3-). Under slightly acidic and neutral conditions, NO^2- formation was more prevalent than NO^3- formation, while under strong acidic conditions, NO^3- was more prevalent. There was no significant change in total organic carbon (TOC) and total nitrogen (TN), suggesting negligible loss of N-nitrosamines and degradation products from the system. NDBA was easily photodegraded than NPYR. This study also demonstrated that a lower pH is a favorable condition for photolytic degradation of N-nitrosamines in water.

• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.15-22
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• 2008

Four series (S, M, R, and W) of Alternaria longipes isolates were obtained based on consecutive selection with Dimethachlon (Dim) and ultraviolet irradiation. These isolates were then characterized according to their tolerance to Dim, sensitivity to osmotic stress, and phenotypic properties. All the selected Dim-resistant isolates showed a higher osmosensitivity than the parental strains, and the last generation was more resistant than the first generation in the M, R, and W series. In addition, the changes in the Dim resistance and osmotic sensitivity were not found to be directly correlated, and no distinct morphologic characteristics were found among the resistant and sensitive isolates, with the exception of the resistant isolate K-11. Thus, to investigate the molecular basis of the fungicide resistance, a group III two-component histidine kinase (HK) gene, AlHK1, was cloned from nineteen A. longipes isolates. AlHK1p was found to be comprised of a six 92-amino-acid repeat domain (AARD), HK domain, and response regulator domain, similar to the Os-1p from Neurospora crassa. A comparison of the nucleotide sequences of the AlHK1 gene from the Dim-sensitive and -resistant isolates revealed that all the resistant isolates contained a single-point mutation in the AARD of AlHK1p, with the exception of isolate K-11, where the AlHK1p contained a deletion of 107 amino acids. Moreover, the AlHK1p mutations in the isolates of each respective series involved the same amino acid substitution at the same site, although the resistance levels differed significantly in each series. Therefore, these findings suggested that a mutation in the AARD of AlHK1p was not the sole factor responsible for A. longipes resistance to dicarboximide fungicides.

• Analytical Science and Technology
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• v.25 no.3
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• pp.197-206
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• 2012

Ambers are composed of polymer molecules which contain aromatic moieties such as benzene, naphthalene, phenanthrene and anthracene. They emit fluorescence when irradiated with ultraviolet light, which was used for confirming an amber. The fluorescence of amber, however, tends to decrease as the surface of amber is weathered with light, heat, oxygen for a long time. In this study, the reliability of confirming amber with its fluorescence by measuring the changes of fluorescence after artificial aging. Aging factors were UV light (${\lambda}$=340 nm), oxygen with heat (100%, $90^{\circ}C$) and heat ($90^{\circ}C$) and aging time was for 5, 15, 30 and 60 days, respectively. In the excitation and emission spectra of amber, the intensity decreased and the maximal wavelength was shifted to longer wavelength with artificial aging time. Especially, there was a drastic decrease in the intensity of spectra to 1.7% of initial value after 60 days aging under oxygen with heat. Only in Colombian amber there showed an increase of fluorescence intensity for a certain aging time, which could be explained by the production of aromatic ring in the presence of light and heat. Conclusively, the fluorescence can be lessened by the natural weathering with light, heat and oxygen and it is not accurate to recognize amber just with UV irradiation method.

• Korean Journal of Environmental Biology
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• v.34 no.1
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• pp.48-55
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• 2016

This study investigates the effect of effluent organic matter (EfOM) from sewage wastewater treatment plants on estrogenic activity reduction of bisphenol A (BPA) by UV photolysis. The EfOM and Suwannee River natural organic matter (SR-NOM) as reference were isolated into hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) fractions depending on polarity. The specific ultraviolet absorbance (SUVA) analysis indicated that EfOM showed similar properties to microbially derived organic matters with low hydrophobicity, which is different from SR-NOM having high hydrophobicity. UV irradiation upto 3 hr significantly reduced SUVA values of both EfOM and SR-NOM (p<0.0001), depending on the polarity of organic matters. In the absence of organic matters, the relative estrogenic activity (REA) of BPA ($5.0{\times}10^{-5}M$) was decreased from 86% to 63% by UV photolysis (2 hr). However, the decrease of mean REA was from 68% to 37% in the presence of organic matters, which was significantly independent on the type (EfOM or SR-NOM) and polarity (HPO, TPI or HPI) of organic matters (p>0.05). As a result, the reduced REA by UV photolysis of BPA with and without organic matters was 31% and 23%, respectively, suggesting that both EfOM and SR-NOM accelerated the photolytic reduction of BPA estrogenic activity.