• 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 Korean Home Economics Education Association
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• v.33 no.1
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• pp.63-79
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• 2021

This study examined yearly trend of sugar-sweetened beverage(SSB) intake and compared nutritional status by SSB intake level in middle school students aged 12~14 years(n=2,543) using the data from 2007~2015 Korea National Health and Nutrition Examination Survey. SSB included carbonated drinks, sports drinks, and caffeinated drinks contained added sugar. Subjects were classified into three groups by SSB intake level obtained from 24-hour recall method: SSB 1(SSB intake 0 g/d), SSB 2(0 g/d < SSB intake < 50th percentile) and SSB 3(SSB intake ≥ 50th percentile). Result of daily intake of SSB was 76.1±6.2 g/d for boys and 59.5±4.7 g/d for girls and it was increased significantly for boys(p-trend 0.0004) and girls(p-trend 0.0038) by year. The most intakes were carbonated drinks followed by fruit juices and sports drinks for boys and girls. Percentage of daily intake compared to the dietary reference was increased for energy and iron while was decreased for calcium and vitamin C toward SSB 3 group. Ratio of excess intake of energy/fat was increased significantly for boys(p=0.0091) and girls(p<0.0001) toward SSB 3 group. Ratio of calcium deficiency was 86.8~94.9% for boys and girls and it was very high. Therefore, it should be emphasized to reduce SSB intake and drink plain water without added sugar, etc. and milk as a source of calcium for improving nutritional status of middle school students through dietary education and social support.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.97-102
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• 2011

Amount of disposed construction materials like waste concrete is growing fast and use of the recycled aggregate for concrete has been seriously considered. But the use of the recycled aggregate is very limited because recycled aggregate has very low quality. Therefore, quality of recycled aggregate is very important in the manufacturing of recycled aggregate concrete. We have studied a series of research according to chemical processes and investigate the alkaline elimination effect of recycled aggregate and quality variation of recycled aggregate by sodium carbonate. Thereafter we have evaluated quality of recycled fine aggregate and experimented quality of this aggregate. As a results, we find that it is easy to eliminate the calcium hydroxide in recycled aggregate by sodium carbonate and the quality of recycled aggregate increase by elimination of alkaline.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.257-262
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• 2015

Recently the world wide efforts reduce occurrence of $CO_2$; global warming main reason. The aim of this study is to improve recycling rate of the fly ash (FA) and fused waste slag (FWS) from the power plant and to carbonate under supercritical condition ($40^{\circ}C$, $80kgf/cm^2$ pressure, 60 min) for $CO_2$ fixation. Specimens of mortar with various mixing ratios of FA, FWS (from 100:0 to 20:80 in 5 steps of 20 % reduction each time), distilled water and 3 M NaOH alkali activators were prepared. As a result, the proportion of weight change ratio increases with CaO content, to 12 % after carbonation under the supercritical condition. There is difference of compressive strength between the carbonated and the alkali activator mortar specimens. The stabilization of $CO_2$ fixation through carbonation which could confirm the applicability of the eco-friendly materials without loss of compressive strength.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.367-375
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• 2007

Critical chloride content for corrosion initiation is a crucial parameter in determining the durability and integrity of reinforced concrete structures, however, the value is still ambiguous. Most of the studies reporting critical threshold chloride content have involved the experimental measurement of the average amount of the total chloride content at arbitrary time. The majority of these researches have not dealt with this issue combined with carbonation of concrete, although carbonation can significantly impact on critical threshold chloride content. Furthermore, the studies have tried to define the critical chloride content within the scope of their experimental concrete mix proportion at arbitrary time. However, critical chloride content for corrosion initiation is known to be affected by a lot of factors including cement content, type of binder, chloride binding, concentration of hydroxyl ions, and so on. It is necessary to define the unified formulation to express the critical chloride content for various mix proportions of concrete. The purpose of this study is to establish an analytical formulation of the critical chloride content of concrete. In this formulation, affecting factors, such as mix proportion, environment, chemical evolution of pore solution with elapsed time, carbonation of concrete and so on are taken into account. Based on the Gouda's experimental results, critical chloride content is defined as a function of $[Cl^-]$ vs. $[OH^-]$ in pore solution. This is expressed as free chloride content with mass unit to consider time evolution of $[OH^-]$ content in pore solution using the numerical simulation programme of cementitious materials, HYMOSTRUC. The result was compared with other experimental studies and various codes. It is believed that the approach suggested in this study can provide a good solution to determine the reasonable critical chloride content with original source of chloride ions, for example, marine sand at initial time, and sea water penetration later on.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.2
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• pp.105-112
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• 2020

As sprout vegetables of interest growing, its maintaining the quality of the technology was needed to solve the problem of increasing growth and maintain quality after harvest. This experiment proved that the quality of radish sprout vegetable was affected by CO₂ treatment during cultivation. Thus, the effect of CO₂ treatment during cultivation on postharvest quality of radish sprout vegetable was investigated in terms of the quality changes in weight loss, gas partial pressure, SPAD, hue angle external appearance during storage at polypropylene film (thickness 30 ㎛) at 10℃. CO₂ treatment used the way to gas with 700 ppm or carbonated water with 700 ppm and 1,400 ppm. The study revealed that growths on CO₂ treated plant were more than those of non-treatment on stem length. After harvesting, the CO₂ treated plant and control growing little different characteristics on fresh weight, plant length and so on. However, there were no differences between the CO₂ treated plant and control on the Fv/Fm and SOD (superoxide dismutase). In gas partial pressure, the O₂ consumption and CO₂ accumulation of the CO₂ treated plant tended to be more than that of non-treated plant. This study also checked that after packaging, the effects of CO₂ treatment during cultivation on the quality of radish sprout vegetable was not significant. However, there were tended to CO₂ treatments were lower value compared to control on SPAD, hue angle and general appearance. CO₂ treatments of radish sprouting vegetable before harvest were improve growth of stem length, but ones were not improving the maintain of quality on radish sprout vegetable during shelf-life period. The results indicated that CO₂ treatment only affected stem elongation until radish sprout vegetable its growth.

• Korean Journal of Human Ecology
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• v.21 no.4
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• pp.805-817
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• 2012

This study was conducted to investigate the preference and consumption status of non-alcohol and alcohol beverages of Korean and Chinese university students in the Jeonbuk area. Self-administered questionnaires were collected from 241 Korean and 198 Chinese students. Statistical data analysis was completed using SPSS v. 12.0. 'Water' was the most commonly consumed non-alcohol beverages by all Korean and Chinese students. The intake frequency of 'carbonated drink' (p<.001), 'fruits/vegetable juice' (p<.05), and 'vinegar drink' (p<.01) of Chinese male students was significantly higher than the Korean male students. The intake frequency of 'ionic drink' (p<.001; p<.01) of Korean male and female students was significantly higher than the Chinese male and female students. The intake frequency of 'fruits/vegetable juice' (p<.001), 'milk' (p<.01), and 'soymilk' (p<.05) of Chinese female students was higher than the Korean female students. For the choosing the non-alcohol beverages, the Chinese female students were more health-oriented than the Korean female students (p<.01). 'Beer' was the most commonly consumed alcohol beverages by the Korean male and female and Chinese male students whereas 'Wine' was the most commonly consumed alcohol beverages by the Chinese female students. The intake frequency of 'Soju' of Korean male (p<.001) and female (p<.001) students was higher than the Chinese male and female students. The intake frequency of 'Wine' of Chinese male (p<.05) and female (p<.001) students higher than the Korean male and female students. Compared with the Chinese female students, the Korean female students more funds have to spend, in order to buy alcohol beverages (p<.01). More 81% of the Korean male and 80% of the female students reported drinking alcohol in 'beer house' whereas 78% of the Chinese male and 65% of female students drunken the alcohol in the 'beer house' or at 'home' (p<.01; p<.001). In conclusion, a practically and foreigner-friendly alcohol policies of university should be devised to reduce the alcohol consumption of students and related problems.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.9
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• pp.1501-1514
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• 2004

The purpose of this study was to evaluate the health condition and nutritional status in female university students in Masan. The 285 subjects aged 20.1 years (18~26 years) were assessed with a set of questionnaire composed of general information, food, smoking, drinking and exercise habits, anthropometric measurements, blood pressure measurements, 24-hour recall and food frequency questionnaire. The rates of smoking and alcohol drinking habits were 1.8% and 82.5%, respectively. All the subjects had the experience of passive smoking. The 11% of the students exercised regularly and 11.6% ate meal regularly. The average height and weight of subjects were 161.0 ㎝ and 53.9 ㎏, respectively and the BMI was calculated as 20.8${\pm}$2.6 ㎏/$m^2$:The 13.3% of subjects were underweight, while 6.7% of them were overweight. The mean value for body fat was 26.4% and subscapular and tricep skinfolds thickness were 14.2 ㎜ and 16.9 ㎜, and waist-hip ratio was 0.72. The systolic/diastolic blood pressure of the subjects was 115.9 ㎜Hg/70.9 ㎜Hg. Except protein, phosphorous, vitamin E, B_6 and C, the average intakes of energy and nutrients were below the Korea recom-mended dietary allowance (RDA). Especially, intakes of calcium, iron and zinc were the lowest, as <70% of RDA. The proportion of energy derived from carbohydrates : protein : fat was 58.0 : 15.8 : 26.2. The 10 frequently consumed food were ssalbap (47.2/mon), kimchi (35.6/mon), onion (16.8/mon), japgokbap (15.1/mon), sesame oil (14.1/mon), carbonated drink (13.3/mon), grapes (12.7/mon), ice cream (12.4/mon), milk (11.9/mon) and water-melon (10.6/mon). Results of this study could be useful for planning nutrition education programs for female university students in this area to improve their dietary habit and health status.

• Journal of Nutrition and Health
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• v.50 no.3
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• pp.270-283
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• 2017

Purpose: This study was conducted to examine coffee consumption behaviors, dietary habits, and nutrient intakes by coffee intake amount among university students. Methods: Questionnaires were distributed to 300 university students randomly selected in Gongju. Dietary survey was administered during two weekdays by the food record method. Results: Subjects were divided into three groups: NCG (non-coffee group), LCG (low coffee group, 1~2 cups/d), and HCG (high coffee group, 3 cups/d) by coffee intake amount and subjects' distribution. Coffee intake frequency was significantly greater in the HCG compared to the LCG (p < 0.001). The HCG was more likely to intake dripped coffee with or without milk and/or sugar than the LCG (p < 0.05). More than 80% of coffee drinkers chose their favorite coffee or accompanying snacks regardless of energy content. More than 75% of coffee takers did not eat accompanying snacks instead of meals, and the HCG ate them more frequently than LCG (p < 0.05). Breakfast skipping rate was high while vegetable and fruit intakes were very low in most subjects. Subjects who drank carbonated drinks, sweet beverages, or alcohol were significantly greater in number in the LCG and HCG than in the NCG (p < 0.01). Energy intakes from coffee were $0.88{\pm}5.62kcal/d$ and $7.07{\pm}16.93kcal/d$ for the LCG and HCG. For total subjects, daily mean dietary energy intake was low at less than 72% of estimated energy requirement. Levels of vitamin C and calcium were lower than the estimated average requirements while that of vitamin D was low (24~34% of adequate intake). There was no difference in nutrient intakes by coffee intake amount, except protein, vitamin A, and niacin. Conclusion: Coffee intake amount did not affect dietary nutrient intakes. Dietary habits were poor,and most nutrient intakes were lower than recommend levels. High intakes of coffee seemed to be related with high consumption of sweet beverages and alcohol. Therefore, it is necessary to improve nutritional intakes and encourage proper water intake habits, including coffee intake, for improved nutritional status of subjects.