• Journal of the Korean Vacuum Society
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• v.20 no.1
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• pp.42-49
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• 2011

We deposited $SiN_x$ thin films by using PECVD technique at $200^{\circ}C$ with various flow ratios of the $SiH_4/N_2$ gases. The photoluminescence measurements revealed that the maximum emission wavelength shifted to long wavelength as the ratio increased, however, positions of the several peak wavelengths, such as 1.9, 2.2, 2.4, and 3.1 eV, were independent on the ratio. Changes of the photoluminescence spectra were measured in the $N_{2}-$, $H_{2}-$, and $O_2$-annealed films. The luminescence intensities increased after the annealing process. In particular, the maximum emission wavelength shifted to short wavelength after $H_{2}-$ or $O_2$-annealing. But there were still several peaks on the spectra of all annealed films, several peak positions remained to be unchanged after the annealing. As for the light emission mechanism, we have considered the defect states of the Si- and N- dangling bonds in the $SiN_x$ energy gap, so that the energy transitions from/to the conduction/valence bands and the defect states in the gap were attributed to the light emission in the $SiN_x$ films. The experimental results point to the possibility of a Si-based light emission materials for flexible Si-based electro-optic devices.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.368-375
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• 2006

Single and complex metal oxide catalysts supported onto a commercial DT51D $TiO_2$ have been investigated for gas-phase TCE oxidation in a continuous flow type fixed-bed reaction system to develop a better design approach to catalysts for this reaction. Among the $TiO_2$-supported single metal oxides used, i.e., $CrO_x,\;FeO_x,\;MnO_x,\;LaO_x,\;CoO_x,\;NiO_x,\;CeO_x\;and\;CuO_x$, with the respective metal contents of 5 wt.%, the $CrO_x/TiO_2$ catalyst was shown to be most active for the oxidative TCE decomposition, depending significantly on amounts of $CrO_x\;on\;TiO_2$. The use of high $CrO_x$ loadings greater than 10 wt.% caused lower activity in the catalytic TCE oxidation, which is probably due to production of $Cr_2O_3$ crystallites on the surface of $TiO_2$. $CrO_x/TiO_2$-supported $CrO_x$-based bimetallic oxide catalysts were of particular interest in removal efficiency for this TCE oxidation reaction at reaction temperatures above $200^{\circ}C$, compared to that obtained with $CrO_x$-free complex metal oxides and a 10 wt.% $CrO_x/TiO_2$ catalyst. Catalytic activity of 5 wt.% $CrO_x-5$ wt.% $LaO_x$ in the removal reaction was similar to or slightly higher than that acquired for the $CrO_x$-only catalyst. Similar observation was revealed for 5 wt.% $CrO_x$-based bimetallic oxides consisting of either 5 wt.% $MnO_x,\;CoO_x,\;NiO_x\;or\;FeO_x$. These results represent that such $CrO_x$-based bimetallic systems for the catalytic TCE oxidation on significantly minimize the usage of $CrO_x$ that is well known to be one of very toxic heavy metals, and offer a very useful technique to design new type catalysts for reducing chlorinated volatile organic substances.

• Journal of Food Hygiene and Safety
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• v.27 no.2
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• pp.152-160
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• 2012

The objective of this study was to analyze hazards for the growing stage of 6 tomato farms (A, B, C; soli farms, D, E, F; Nutriculture farms) located in Gyeongsangnam-do to establish the good agricultural practices (GAP). A total of 144 samples for analyzing hazards collected from cultivation environments (irrigation water, soil, nutrient solution, and air) and personal hygiene (hands, gloves, and cloths) were assessed for biological (sanitary indications and major food borne pathogens) and chemical hazards (heavy metals). Total bacteria, coliform, and fungi were detected at levels of 0.2-7.2, 0.0-6.1, and 0.0-5.4 log CFU/g, mL, hand or 100 $cm^2$, respectively. Escherichia coli were only detected in the soil sample from B farm. In case of pathogens, Bacillus cereus was detected at levels of 0.0-4.4 log CFU/(g, mL, hand or 100 $cm^2$), whereas Staphylococuus aureus, Listeria monocytogenes, E. coli O157, and Salmonella spp. were not detected in all samples. Heavy metals as a chemical hazard were detected in soil and irrigation water, but levels of them were lower than the permit limit. In conclusion, chemical hazard levels complied with GAP criteria, but biological hazards at the growing stage of tomato farms were confirmed. Therefore a proper management to prevent microbial contamination is needed.

• Journal of Plant Biotechnology
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• v.45 no.3
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• pp.171-182
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• 2018

Papaya (Carica papaya L.) is one of the crops widely planted in tropical and subtropical areas. The papaya fruit has low calories and are plentiful in vitamins A and C and in minerals. A major problem in papaya production is a plant disease caused by the papaya ringspot virus (PRSV). The first PRSV-resistant GM papaya expressing a PRSV coat protein gene was developed by USA scientists in 1992. The first commercial GM papaya cultivars derived from the event was approved by the US government in 1997. Development of transgenic papayas has been focused on vaccine production and limited agricultural traits, including insect and pathogen resistance, long shelf life, and aluminum and herbicide tolerance. Approximately 17 countries, including the USA and China, produced transgenic papayas and/or commercialized them, which provoked studies on biosafety assessment and development of GM-detection technologies. For the biosafety assessment of potential effects on human health, effects of long-term feeding to model animals have been studied in terms of toxicity and allergenicity. Studies on environmental safety assessment include influence on soil-microbial biodiversity and transfer to soil bacteria of GM selection markers. Many countries, such as Korea, the European Union, and Japan, that have strict regulations for GM crops have serious concerns about unintended introduction of GM cultivars and food commodities using unauthorized GM crops. Transgene- and/or GM event-specific molecular markers and technologies for genomics-based detection of unauthorized GM papaya have been developed and have resulted in the robust detection of GM papayas.

• Journal of Nutrition and Health
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• v.35 no.4
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• pp.464-472
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• 2002

This study was conducted to investigate dietary and other factors affecting bone mineral density in young Korean collage women. Thirty subjects were recruited; the mean age was 22.1 years and the mean age at menarche was 12.6 years. Bone mineral density (BMD) was measured in the spine (LS), femoral neck (FN), ward's triangle (WT), and femoral trochanter (FT) by Dual Energy X-ray Absorptiometry (DEXA), and physical activity was assessed by a questionnaire. Dietary intake data were obtained 8 times by using a 24 hour recall method to evaluate the subjects' usual diet. Bone mineral densities of lumbar spine, femoral neck, ward's triangle and femoral trochanter were 1.149 g/$\textrm{cm}^2$, 0.980 g/$\textrm{cm}^2$, 0.936 g/$\textrm{cm}^2$ and 0.759 g/$\textrm{cm}^2$ respectively. The met energy intake of subjects was 1,790 kcal, and calcium and iron intakes were found to be inadequate compared to the Korean RDA. The BMD of the lumbar spine was significantly and positively related to the BMI and intake of vitamin C, carbohydrate, potatoes, fruits and plant food. The BMD of the femur (FN, WT, FT) was positively related to the BMI, to carbohydrate and fruit intake, and to the percentage of plant food in total food intake. Multiple recession analysis showed that fruit intake was significantly related to the BMD of the LS. The subjects'ages and fruit intakes were significantly related to the BMD of the femur (FN, WT, FT). These results indicate that higher fruit intakes may have a beneficial effect on bone mineral density.

• Journal of Life Science
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• v.21 no.9
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• pp.1214-1218
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• 2011

We investigated the fruits of Rubus crataegifolius Bge, a plant which has been traditionally used in Korea in phytotherapy, to describe antioxidant materials from plant sources. R. crataegifolius fruits were extracted with methanol and further fractionated into n-hexane, diethyl ether, and ethyl acetate. The antioxidant activity of each fraction and the residue was assessed using a 1,1-diphenyl-2-picrylhydrazyl (DPPH), $H_2O_2$ radical scavenging method, and their cytotoxicity on human primary kerationcyte (HK) was determined by an MTS assay. The R. crataegifolius fruit methanol extract showed strong antioxidant activity (75.04%, 50%) compared with vitamin C (79.9%, 54.1%) by the DPPH, and $H_2O_2$ method, respectively. The measured activity from the subsequent extracts of the methanol extract were 20.3% for n-hexane fraction (HF), 68.8% for diethyl ether fraction (DF), 67.1% for ethyl acetate fraction (EF), and 67.1% for the residue fraction (RE) by DPPH and 2.2% for HF, 1.6% for DF, 10% for EF, and 50% for the RE by $H_2O_2$ assay. An oxidative stress model of HK was established under a suitable concentration (1 mM). The cell viability of the RE treated group increased and the percentage of apoptotic cells decreased at concentrations of 0.005-0.02% RE compared with the $H_2O_2$ treated group. Fruit extracts of the medicinal plant R. crataegifolius showed potent antioxidant activity and the ability to relieve cell damage from $H_2O_2$ induced injury to HK.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.397-405
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• 2021

With the recent phenomenon of the Intelligence Information Society, the cyber security paradigm has begun to change. In particular, the increase of the interconnectedness of the hyperlinked society has extended the scope of damage that can be caused by cyber threats to the real world. In addition to that, it can also be a risk to any given individual who could accompany a crisis that has to do with public safety or national security. Adolescents who are digital natives are more likely to be exposed to cyber threats, which is mainly due to the fact that they are significantly more involved in cyber activities and they also possess insufficient security comprehension and safety awareness. Therefore, it is necessary to strengthen cyber security capabilities of every young individual, so that they can effectively protect themselves against cyber threats and better manage their cyber activities. It examines the changes of the security paradigm and the necessity for cyber security education, which is in direct accordance to the characteristics of a connected society that further suggests directions and a basic system of cyber security education, through a detailed analysis of the current state of Domestic and Overseas Cyber Security Education. The purpose of this study was to define cybersecurity competencies that are necessary within an intelligent information society, and to propose a regular curriculum for strengthening cybersecurity competencies, through the comparison and meticulous analysis of both domestic and overseas educational systems that are pertinent to cybersecurity competencies. Accordingly, a cybersecurity competency system was constructed, by reflecting C3-Matrix, which is a cyber competency system model of digital citizens. The cybersecurity competency system consists of cyber ethics awareness, cyber ethics behavior, cyber security and cyber safety. In addition to this, based on the basic framework of the cybersecurity competency system, the relevant education that is currently being implemented in the United States, Australia, Japan and Korea were all compared and analyzed. From the insight gained through the analysis, the domestic curriculum was finally presented. The main objective of this new unified understanding, was to create a comprehensive and effective cyber security competency curriculum.

• Resources Recycling
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• v.31 no.5
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• pp.67-76
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• 2022

The furniture industry has a high possibility to create value-added and a high potential to create new occupations due to the characteristics of the industry, which mainly consists of small and medium-sized enterprises (SMEs). However, the used furniture, which has sufficient reuse value, is also crushed and used as solid refuse fuel (SRF) recently. Besides, the number of waste treatment companies continues to decrease, and it occurs congestion of wood waste. As a way to solve the issue, a business model development of remanufacturing used furniture can be suggested as an alternative due to its high circular economic efficiency. Remanufacturing business including furniture industry creates positive effects in various aspects such as economic, environmental and job creation. In other words, remanufacturing is an effective recycling way to reduce input resources and energy in the production process. The results of economic analysis show that the expected annual revenue from the single worker furniture remanufacturing site was 104 million won which is 3.11 times more than the average income of a single-worker household in Korea and its B/C ratio was estimated about 30 which means high business feasibility. Revenue through furniture remanufacturing also showed 320 times higher than that of SRF production from the perspective of weight. In addition, it is shown that the GHGs reduction from the furniture remanufacturing is 2.2 ton CO₂-eq. per year, which is similar to the amount of GHGs absorption effect of 937 pine trees or 622 Korean oak trees annually. Thus the results of this study demonstrate that it is important to adopt an appropriate recycling method considering the economic and environmental effects at the end-of-life stage.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.4
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• pp.218-227
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• 2006

Purpose: The HSV1-tk reporter gene system is the most widely used system because of its advantage that direct monitoring is possible without the introduction of a separate reporter gene in case of HSV1-tk suicide gene therapy. In this study, we investigate the usefulness of the reporter probe (substrate), $9-(4-[^{18}F]Fluoro-3-hydroxymethylbutyl)$guanine ($[^{18}F]FHBG$) for non-invasive reporter gene imaging using PET in HSV1-tk expressing hepatoma model. Materials and Methods: Radiolabeled FHBG was prepared in 8 steps from a commercially available triester. The labeling reaction was carried out by NCA nucleophilic substitution with $K[^{18}F]/K2.2.2.$ in acetonitrile using N2-monomethoxytrityl-9-14-(tosyl)-3-monomethoxytritylmethylbutyl]guanine as a precursor, followed by deprotection with 1 N HCl. Preliminary biological properties of the probe were evaluated with MCA cells and MCA-tk cells transduced with HSV1-tk reporter gene. In vitro uptake and release-out studies of $[^{18}F]FHBG$ were performed, and was analyzed correlation between $[^{18}F]FHBG$ uptake ratio according to increasing numeric count of MCA-tk cells and degree of gene expression. MicroPET scan image was obtained with MCA and MCA-tk tumor bearing Balb/c-nude mouse model. Results: $[^{18}F]FHBG$ was purified by reverse phase semi-HPLC system and collected at around 16-18 min. Radiothemical yield was about 20-25%) (corrected for decay), radiochemical purity was >95% and specific activity was around >55.5 $GBq/{\mu}\;mol$. Specific accumulation of $[^{18}F]FHBG$ was observed in HSV1-tk gene transduced MCA-tk cells but not in MCA cells, and consecutive 1 hour release-out results showed more than 86% of uptaked $[^{18}F]FHBG$ was retained inside of cells. The uptake of $[^{18}F]FHBG$ was showed a highly significant linear correlation ($R^2=0.995$) with increasing percentage of MCA-tk numeric cell count. In microPET scan images, remarkable difference of accumulation was observed for the two type of tumors. Conclusion: $[^{18}F]FHBG$ appears to be a useful as non-invasive PET imaging substrate in HSV1-tk expressing hepatoma model.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.316-323
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• 1991

We calculated a difference between the YBa$_2Cu _3O_{7-x}$ superconductor (123 system) of critical temperature, 95 K and the YBa$_2Cu_4 O_8$ superconductors (124 system) of critical temperature, 80 K in Y-system superconductors using Extended Huckel Theory (EHT). The valence electron population (VEP), reduced overlap population (ROP) and net charge for the charged cluster models relating to the layer and the chain in 123 and 124 systems were compared. The VEPs of Cu atom in the layer of 123 and 124 systems populated d$_{z^2}$ orbital more than d$_{x^2-y^2}$ orbital, and in the chain of 123 and 124 systems populated d$_{y^2-z^2}$ orbital more than d$_{z^2}$ orbital. The ROP of the Cu(1)-O(1) in the layer of 123 system was larger than the value of the Cu(1)-O(2), but the ROP of the Cu(1)-O(2) in the layer of 124 system was larger than the value of the Cu(1)-O(1). The ROP of Cu(2)-O(4) in the chain of 123 and 124 systems were larger than the value of the Cu(2)-O(3). In 123 system the net charge values of the Cu in the layer was larger than the value of the Cu in the chain. However, in 124 system the net charge value of the Cu in the chain was larger than the value in the layer.