• Horticultural Science & Technology
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• v.34 no.4
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• pp.596-606
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• 2016

The growth and contents of anthocyanins and ascorbic acid in lettuce(Lactuca sativa L., 'Jeokchima') as affected by supplemental UV-A LED irradiation under different light quality and photoperiod conditions were analyzed in this study. Five light qualities, namely B (blue LED), R (red LED), BUV (blue LED+UV-A LED), RUV (red LED+UV-A LED) and Control (white fluorescent lamps) with photoperiods of 12/12 hours (day/night), 16/8 hours, or 20/4 hours were provided to investigate the effects of light quality and photoperiod on the growth and accumulation of anthocyanins and ascorbic acid in lettuce leaves. As measured 28 days after transplanting, the number of leaves, leaf length, leaf width, leaf area, shoot fresh weight and dry weight of lettuce were significantly affected by light quality and photoperiod. The number of leaves, leaf length, leaf width, leaf area, shoot fresh weight and dry weight of lettuce grown under R treatment increased with increasing light period. By contrast, leaf development was inhibited, but chlorophyll content increased, under B treatment. Supplemental UV-A irradiation significantly decreased leaf length, leaf width, leaf area and shoot fresh weight. Anthocyanins in lettuce increased significantly with decreasing dark period under B treatment. A synergistic effect of supplemental UV-A LED irradiation on anthocyanins accumulation was found for lettuce leaves grown under R treatment but not B treatment. Ascorbic acid in lettuce was greatly affected by photoperiod. Ascorbic acid content at BUV and RUV treatments increased by 20-30% compared to without UV-A LED irradiation. From these results, it was concluded that growth and contents of anthocyanins and ascorbic acid in lettuce are significantly affected by supplemental UV-A LED irradiation. The results obtained in this study will be informative for efforts to improve the nutritional value of leafy vegetables grown in plant factories.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.386-392
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• 2017

This study was conducted to examine the growth and phytochemical contents of spinach (Spinacia Oleracea L. 'Sushiro') as affected by different fluorescent lamps in a closed-type plant production system. Seeds were sown in a 128-cell plug tray filled in rockwool. The seedlings were transplanted into a DFT (deep floating technique) system with recycling nutrient solution (EC $1.5dS{\cdot}m^{-1}$ and pH 6.5) in a closed-type plant production system. The seedlings were grown under 3 types of fluorescent lamp, #S (NBFHF 32S8EX-D, CH LIGHTING Co. Ltd., China), #O (FHF32SSEX-D, Osram Co. Ltd., Germany), and #P (FLR32SS EX-D, Philips Co. Ltd., The Netherlands) at $150{\mu}mol{\cdot}m-2{\cdot}s^{-1}\;PPFD$ with a photoperiod of 14/10 (light/dark) hours. Plants were cultured under condition of $25{\pm}1^{\circ}C$ temperature and $60{\pm}10%$ relative humidity after transplanting. Thirty plants per each treatment were cultivated for $6^{th}$ week after transplanting. And growth and phytochemical contents were measured at $3^{rd}$ and $6^{th}$ week. At the $3^{rd}$ week after transplanting, the parameter values of plant height and leaf width were higher in the #O than the others. However, fresh and dry weights of root were the greatest in the #P. In addition, total phenolic concentration was the greatest in the #P. At $6^{th}$ week after transplanting, the #O had the greatest growth of spinach in the plant height and fresh and dry weights of shoot. The total phenolic contents significantly increased in the #O and showed significantly difference. However, there was no significant difference all treatments in antioxidant activity. Therefore, these results suggest that the #O was suitable for the growth and phytochemical accumulation of spinach in a closed-type plant production system.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.254-262
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• 2003

Dental caries has a multifactorial aetiology in which there is an interplay of three principal factors: the host(saliva and teeth), the microflora(dental plaque) and the substrate(diet), and a fourth factor time. There is no single test that takes into consideration all these factors and can accurately predict an individual's susceptibility to dental caries. The risk of dental caries can be evaluated by analysing and integrating several causative factors. The objective of the study was to clarify the relationship between caries activity and the status of caries of primary teeth and the relationship between the quantity of S. mutans in the dental plaque and the status of dental caries. Forty nine children ages 5 were examined with caries indices, Dentocult-SM and quantity of S. mutans. The results were as follows: All the survey results were similar with national means of 5-6 years Korean preschool children. The deft index of subjects was 5.46 and defs index was 9.81. There was 8.6% of negative, 10.9% of mild, 28.1% of moderate and 52.3% of active results at screening strip test. 8.6% was negative, 17.2% was mild, 33.6% was moderate and 40.6% was active in site strip test. The Spearman correlation coefficient was 0.775, and overall kappa index was 0.496 between screening strip test and site strip test. There also was a high correlation between caries incidence, Dentocult-SM test, and quantity of S. mutans. Dentocult-SM test as a caries activity test is a reliable method for measuring the status of dental caries in primary teeth.

• Journal of the Mineralogical Society of Korea
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• v.30 no.2
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• pp.59-70
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• 2017

$SiO_2$ is one of the most abundant constituents of the Earth's crust and mantle. Probing its electronic structures at high pressures is essential to understand their elastic and thermodynamic properties in the Earth's interior. The in situ high-pressure x-ray Raman scattering (XRS) experiment has been effective in providing detailed bonding transitions of the low-z materials under extreme compression. However, the relationship between the local atomic structures and XRS features at high pressure has not been fully established. The ab initio calculations have been used to overcome such experimental difficulties. Here we report the partial density of states (PDOS) of O atoms and the O K-edge XRS spectra of ${\alpha}-quartz$, ${\alpha}-cristobalite$, and $CaCl_2$-type $SiO_2$ phases calculated using ab initio calculations based on the full-potential linearized augmented plane wave (FP-LAPW) method. The unoccupied O PDOSs of the $CaCl_2$-type $SiO_2$ calculated with and without applying the core-hole effects present significantly distinctive features. The unoccupied O p states of the ${\alpha}-quartz$, ${\alpha}-cristobalite$ and $CaCl_2$-type $SiO_2$ calculated with considering the core-hole effect present similar features to their calculated O K-edge XRS spectra. This confirms that characteristic features in the O K-edge XRS stem from the electronic transition from 1s to unoccupied 2p states. The current results indicate that the core-hole effects should be taken in to consideration to calculate the precise O K-edge XRS features of the $SiO_2$ polymorphs at high pressure. Furthermore, we also calculated O K-edge XRS spectrum for $CaCl_2$-type $SiO_2$ at ~63 GPa. As the experimental spectra for these high pressure phases are not currently available, the current results for the $CaCl_2$-type $SiO_2$ provide useful prospect to predict in situ high-pressure XRS spectra.

• The Journal of Korean Society for School & Community Health Education
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• v.14 no.3
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• pp.27-40
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• 2013

Objectives: This study was conducted at a request for cooperation through an analysis of the effect of toothbrushing facilities at a public health center in Seongdong-gu. Also, with the aim of furnishing basic data to the proposal of a program for improving the ability of school aged children in managing oral cavities and developing a correct toothbrushing habit, the study conducted an investigation of how toothbrushing facilities affect change in the oral environment management ability and behavior of oral health care. Methods: From among elementary schools located in Seongdong-gu, Seoul the study selected A Elementary School where toothbrushing facilities were established and have been operated since 2008, B Elementary School in an adjacent region within the jurisdiction of Seongdong-gu where the demographic environment was similar among schools where toothbrushing facilities were newly established in 2012, and C Elementary School without toothbrushing facilities. Then the study was aimed at first grade students of the schools and an investigation was carried out from April to December 2012. Through a dental checkup, the study evaluated the teeth and periodontal health conditions, and a test of the oral environment management ability was undertaken three times. Regarding change of oral health care behavior, the study carried out a self-recording survey. Results: 1. Concerning decayed and filled tooth(dft) and decayed and filled surface (dfs), A Elementary School where toothbrushing facilities have been established and operated from the past showed a relatively lower decayed, missing, and filled teeth index than B Elementary School where toothbrushing facilities were established in 2012 or C Elementary School without toothbrushing facilities; however, there was no significant difference (p>0.05). For CPI, there was no significant difference by school; however, in looking into the difference between boy students and girl students, Code (0) was discovered higher in boy students whereas Code (1) was shown higher in girl students. 2. In the PHP index test in accordance with the existence of toothbrushing facilities before the installation of toothbrushing facilities, for A Elementary School where toothbrushing facilities have been established and operated from the past, the school recorded 4.28 points whereas B Elementary School where the facilities were established in 2012 recorded 3.51 points. Meanwhile C Elementary School without the facilities posted 4.30 points. Therefore there was a statistically significant difference according to the existence of toothbrushing facilities (p<0.05). 3. In a comparison of teeth health care behavior according to the existence of toothbrushing facilities, the number of answers that the respondent did not brush their teeth after lunch over the past one week was higher in B Elementary School and C Elementary School where there were no toothbrushing facilities. Regarding the average number of brushing after lunch for one week, it was discovered higher in A Elementary School (p<0.01). 4. In change of teeth health care behavior before and after the establishment of toothbrushing facilities, the case of answering that the respondents did not brush their teeth after lunch for one week increased more after establishment than before establishment. Also the average number of teeth brushings after lunch for one week decreased further after the establishment of toothbrushing facilities; however, it did not show a significant difference (p>0.05). One of the reasons that they do not brush their teeth, "the lack of a place", decreased significantly after establishment than before establishment (p<0.05), whereas the answer, "because their friends do not brush their tooth" increased greatly after establishment than before establishment; however, there was no significant difference (p>0.05). 5. In the comparison of the degree of knowledge about dental health according to the existence of toothbrushing facilities, the degree of knowledge about dental health was shown significantly higher in A Elementary School with toothbrushing facilities than in B Elementary School and C Elementary School where there were no toothbrushing facilities (p<0.01). Conclusions: Given the above results, it is difficult to attract change in behavior only with an environmental improvement; therefore, it is deemed necessary to develop an educational program that will help children to make a habit of oral health care not only through a school but also through a related policy and financial support of government organizations as well as the construction of the basis of a systematic and consistent cooperative system with relevant organizations.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.85-93
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• 2021

In hydroponic cultivation, in order to investigate the change of lettuce growth and physiologically active substances through CO2 tablet treatment in nutrient solution, we used a solid carbonated tablets commercially available in the Netherlands. The experiment consisted of 0.5-fold, 1-fold, and 2-fold treatment groups with no treatment as a control. As a result, the atmospheric CO2 concentration in the chamber after CO2 tablet treatment showed the highest value at 472.2 µL·L-1 in the 2-fold treatment zone immediately after treatment, and the pH in the nutrient solution decreased the most to pH 6.03 in the 2-fold treatment zone. After that, over time, the CO2 concentration and pH recovered to the level before treatment. Leaf width and leaf area of lettuce showed the highest values of 17.1cm and 1067.14 ㎠ when treated 2-fold with CO2 tablet, while fresh weight and dry weight of the above-ground part were highest at 63.87 g and 3.08 g in 0.5-fold treatment. The root length of lettuce was the longest (28.4 cm) in the control, but there was no significant difference in the fresh weight and the dry weight among the treatments. Apparently, it was observed that the root length of the lettuce was shortened by CO2 tablet treatment and a lot of side roots occurred. In addition, there was a growth disorder in which the roots turned black, but it was found that there was no negative effect on the growth of the above-ground part. As a result of analyzing the bioactive compounds of lettuce by CO2 tablet treatment, chlorogenic acid and quercetin were detected. As a result of quantitative analysis, chlorogenic acid increased by 249% compared to the control in 1-fold treatment, but quercetin decreased by 37%. As a result of comparing the DPPH radical scavenging ability showing antioxidant activity, the control and 0.5-fold treatment showed significantly higher values than the 1-fold and 2-fold treatments. This suggests that carbonated water treatment is effective in increasing the growth and bioactive compounds of hydroponic lettuce.

• Journal of agriculture & life science
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• v.53 no.1
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• pp.13-21
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• 2019

This study was carried out to acquire basic data for a long-term hydroponic culture through investigating water and inorganic ion uptake characteristics at different EC level of nutrient solution of three tomato varieties. Three different tomato varieties, the European type(cv. Daphnis), the Asian type(cv. Super Doterang) and cherry type(cv. Minichal), were used for the investigation. Also, the deep flow technique(DFT) was applied. The three different electrical conductivity(EC) level(1.0, 2.0, 3.0, and 4.0 dS·m-1) of hydroponic nutrient solution were used as variable. At a high EC level of nutrient solution, the leaf area and fresh weight decreased in the early stage, and its growth(plant height, leaf number, leaf area, fresh-weight) was poor with salt stress. Result showed that the higher the EC level of the nutrient solution, the lesser was water uptake. The water uptake was not significantly different from varieties in the first survey, but In the second survey, the 'Daphnis' did not show a significant decrease in water uptake in the EC level higher than 2.0 dS·m-1., on the other hand, 'Super Doterang' presented very low water uptake. At a low EC level, N, P, and K, were absorbed more than the concentration of the irrigation water, while Ca, Mg, S uptake were low. At a high EC level, almost ions absorbed less than 50% of the initial concentration of irrigation water. Thus, imbalance among ions was severe at low EC level compared to high EC level. 'Daphnis' was a variety that effectively utilize nutrients under nutrient stress, showing high absorption at low concentration condition and low absorption at high concentration condition. However, 'Daphnis' suffered most seriously by absorbing nutrients excessively.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.1-9
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• 2021

This study was conducted to examine the changes of photosynthesis, growth, chlorophyll contents and functional material contents in light intensity and EC concentration of wild baby leaf vegetable, Indian lettuce (Lactuca indica L. cv. 'Sunhyang') in DFT hydroponics. The cultivation environment was 25±1℃ of temperature and 60±5% of relative humidity in growth system. At 14 days after sowing, combination effect of light intensity (Photosynthetic Photon Flux Density (PPFD 100, 250, 500 µmol·m-2·s-1) and EC level (EC 0.8, 1.4, 2.0 dS·m-1) of nutrient solution was determined at the baby leaf stage. The photosynthesis rate, stomatal conductance, transpiration rate and water use efficiency of Indian lettuce increased as the light intensity increased. The photosynthesis rate and water use efficiency were highest in PPFD 500-EC 1.4 and PPFD 500-EC 2.0 treatment. The chlorophyll content decreased as the light intensity increased, but chlorophyll a/b ratio increased. Leaf water content and specific leaf area decreased as light intensity increased and a negative correlation (p < 0.001) was recognized. Plant height was the longest in PPFD 100-EC 0.8 and leaf number, fresh weight and dry weight were the highest in PPFD 500-EC 2.0. Anthocyanin and total phenolic compounds were the highest in PPFD 500-EC 1.4 and 2.0 treatment, and antioxidant scavenging ability (DPPH) was high in PPFD 250 and 500 treatments. Considering the growth and functional material contents, the proper light intensity and EC level for hydroponic cultivation of Indian lettuce is PPFD 500-EC 2.0, and PPFD 100 and 250, which are low light conditions, EC 0.8 is suitable for growth.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.225-236
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• 2019

BACKGROUND: Hydroponics is one of the methods for evaluating plant production using the inorganic nutrient solutions, which is applied under the artificial light conditions of plant factory system. However, the application of the conventional inorganic nutrients for hydroponics caused several environmental problems: waste from culture mediums and high nitrate concentration in plants. Organic nutrients are generally irrigated as a supplementary fertilizer for plant growth promotion under field or greenhouse conditions. Hydroponic culture using organic nutrients derived from the agricultural by-products such as dumped stems, leaves or immature fruits is rarely considered in plant factory system. Effect of organic or conventional inorganic nutrient solutions on the growth and nutrient absorption pattern of green and red leaf lettuces was investigated in this experiment under fluorescent lamps (FL) and mixture Light-Emitting Diodes (LEDs). METHODS AND RESULTS: Single solution of tomatoes (TJ) and kales (K) deriving from agricultural by-products including leaves or stems and its mixed solution (mixture ration 1:1) with conventional inorganic Yamazaki (Y) were supplied for hydroponics under the plant factory system. The Yamazaki solution was considered as a control. 'Jeockchima' and 'Cheongchima' lettuce seedlings (Lactuca sativa L.) were used as plant materials. The seedlings which developed 2~3 true leaves were grown under the light qualities of FL and mixed LED lights of blue plus red plus white of 1:2:1 mixture in energy ratio for 35 days. Light intensity of the light sources was controlled at 180 μmol/㎡/s on the culture bed. The single and mixture nutrient solutions of organic and/or inorganic components which controlled at 1.5 dS/m EC and 5.8 pH were regularly irrigated by the deep flow technique (DFT) system on the culture gutters. Number of unfolded leaves of the seedlings grown under the single or mixed nutrient solutions were significantly increased compared to the conventional Y treatment. Leaf extension of 'Jeockchima' under the mixture LED radiation condition was not affected by Y and YK or YTJ mixture treatments. SPAD value in 'Jeockchima' leaves exposed by FL under the YK mixture medium was approximately 45 % higher than under conventional Y treatment. Otherwise, the maximum SPAD value in the leaves of 'Cheongchima' seedlings was shown in YK treatment under the mixture LED lights. NO₃-N contents in Y treatment treated with inorganic nutrient at the end of the experiment were up to 75% declined rather than increased over 60 % in the K and TJ organic treatment. CONCLUSION: Growth of the seedlings was affected by the mixture treatments of the organic and inorganic solutions, although similar or lower dry weight was recorded than in the inorganic treatment Y under the plant factory system. Treatment Y containing the highest NO₃-N content among the considered nutrients influenced growth increment of the seedlings comparing to the other nutrients. However effect of the higher NO₃-N content in the seedling growth was different according to the light qualities considered in the experiment as shown in leaf expansion, pigmentation or dry weight promotion under the single or mixed nutrients.