• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.2
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• pp.107-118
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• 2021

Due to the acceleration of road construction, the number and extension of tunnels are increasing every year. A lot of research has been done on the collapse of tunnels, but research on the invert heaving is insufficient. Therefore, in this study, a sensitivity analysis was performed using a geotechnical general-purpose program to analyze the effect of the invert curvature of a tunnel excavated on the soft ground. As a result, it was quantitatively confirmed that the stability of a tunnel was increased as the curvature of the tunnel invert was increased so that the safety factor was calculated to be large regardless of the ground conditions and the thickness of the support. In addition, it was confirmed that the stability of the tunnel was increased by reducing the convergence of the tunnel and the maximum bending stress supported by shotcrete. Therefore, when a tunnel is excavated on soft ground, it is believed that applying a curvature to the invert will increase the stability of the tunnel.

• Journal of the Korean GEO-environmental Society
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• v.12 no.6
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• pp.17-23
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• 2011

In this study, a series of experiments were carried out to remove total petroleum hydrocarbon(TPH) and toluene by soil flushing. In batch experiments, Triton X-100 and SWA 1503 showed TPH removal efficiency of 79.0% and 69.0%, respectively. Although the TPH removal efficiency increased as the surfactant was increased in the concentration range 1-11mmol/L, the optimum concentration was 1mmol/L, considering the ratio of the removal efficiency to the amount of surfactant injected. In column experiment, the optimal velocity was 0.3mL/min. The physical aquifer model(PAM) result revealed that the soil flushing removed as much as 5.5% of the toluene under 3 pore volume(PV) conditions. To improve the soil flushing efficiency, it is necessary to find optimal condition through recirculation or reuse of surfactant.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.319-322
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• 2011

N,N'-Dicyclohexylcarbodiimide (DCC) known as powerful dehydrating reagent in amide or ester synthesis is converted into N,N'-dicyclohexylurea (DCU) during the reaction. In the paper, DCU was recovered from the reaction for the synthesis of the hydrophilic derivative of ${\beta}$-sitosterol, and the purification of the recovered DCU and the dehydration of DCU into DCC were investigated. In the presence of tosyl chloride, (TsCl) and triethylamine (TEA), DCU was converted into DCC, and the optimum molar ratio of [DCU] : [TsCl] : [TEA] was found to be 1.0 : 1.5 : 3.0. Pure DCC was obtained with a 46% yield by the sublimation after the purification process, and characterized by GC/MS, FT-IR and $^{13}C-NMR$.

• Journal of the Korean Dietetic Association
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• v.27 no.2
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• pp.67-76
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• 2021

The purpose of this survey was to investigate the food behavior and vegetable preferences of elementary school students in the metropolitan areas of, South Korea. Five hundred and eighty students (277 male and 303 female) studying in grades 5~6 participated in the survey. We assessed food behavior by evauating the Nutrition Quotient (NQ). Through a questionnaire, which consisted of 20 food behavior checklist items. These items were grouped under five factors: balance, diversity, moderation, practice and environment. All data were analyzed using SPSS 25.0. The average NQ score weighted using the five factors was 61.32 points. Among the five factors, moderation showed the lowest score, whereas environment showed the highest score. The average score of the vegetable preference was 3.36 points out of a total of 5 points. The vegetable preference was found to be highest for bean sprouts and followed by tomatoes, lettuce, spinach, Chinese cabbage, sesame leaf, pumpkin, carrot, radish, chives, lotus roots, onions, broccoli, sweet peppers, and eggplant. The results of vegetable preferences by NQ grade were 4.13±0.63 points for the high grade, 3.68±0.75 points for the medium-high grade, 3.41±0.82 points for the medium-low grade, and 2.94±0.78 points for the low grade. There was a significant positive correlation between NQ and vegetable preferences (r=0.477, P<0.001). If vegetables with high preference are frequently provided in school meals, it might contribute to improving overall food behavior.

• Journal of Korea Water Resources Association
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• v.54 no.8
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• pp.599-606
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• 2021

Water Distribution Networks, one of the social infrastructures buried underground, has the function of transporting and supplying purified water to customers. In recent years, as measurement capability is improved, a number of studies related to leak recognition and detection by applying a deep learning technique based on flow rate data have been conducted. In this study, a cognitive model for leak occurrence was developed using an LSTM-based deep learning algorithm that has not been applied to the waterworks field until now. The model was verified based on the assumed data, and it was found that all cases of leaks of 2% or more can be recognized. In the future, based on the proposed model, it is believed that more precise results can be derived in the prediction of flow data.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.574-580
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• 2022

While in the process of electroless plating of dendrite-shape copper with silver, various silver-coated copper (Ag@Cu) particles were prepared by using both displacement plating and reducing electroless plating. The physicochemical properties of Ag@Cu particles were analyzed by scanning electron microscope- energy-dispersive X-ray spectroscopy (SEM-EDS), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Brunauer-Emmett-Teller analysis (BET), and it was confirmed that the silver coated by the reducing electroless plating was formed as nano-particles on the copper surface. Ag@Cu particles were compounded with an epoxy resin to prepare a conductive film, and its thermal stability was evaluated. We investigated the effect of the difference between the displacement plating and reducing electroless plating on the initial resistance and thermal stability of conductive films.

• Korean Journal of Community Nutrition
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• v.27 no.5
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• pp.397-405
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• 2022

Objectives: This study examines the effect on the frequency of ramyeon consumption based on who checks nutrition labels and on the levels of sodium-related nutrition knowledge among middle school students in the Incheon area. Methods: Self-administered questionnaires were completed by 359 students (143 males and 216 females) from May to October 2021. General information as well as ramyeon-eating behaviors were surveyed. The frequency of ramyeon consumption was compared depending on who checks nutrition labels and on the amount of sodium-related nutrition knowledge students have. Both 𝛘² tests and t-tests were conducted for categorical and mean comparisons. Results: Regarding the consumption of ramyeon, 46% of the students replied that they eat it alone at home. The criteria for choosing the kind of ramyeon to eat were taste (79.4%), price (9.2%), brand and new products (4.5%), nutrition (2.2%), weight control (2.2%), and other factors (2.5%). When purchasing ramyeon, more students replied that they did not read nutrition labels (66.0%) compared to those who did read labels (34.0%). Answers to questions on sodium-related nutrition earned an average of 6.84 out of nine points (males, 6.72 points, females, 6.91 points, ns). The average frequency of ramyeon consumption was 1.67 times per week (males, 1.66, females, 1.68, ns). The frequency of ramyeon consumption by students who checked nutrition labels was lower than for students who did not check labels (1.44 times per week vs. 1.79 times per week, P < 0.05). Conclusions: Students who checked nutrition labels reported a lower frequency of ramyeon consumption than students who did not check them. Education on checking nutrition labels may reduce the consumption of processed foods such as ramyeon and may lead to making healthy choices when purchasing food.

• Journal of the Korean Dietetic Association
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• v.29 no.1
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• pp.49-64
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• 2023

Osteoporosis is a major health problem confronting middle-aged women today. Enhancing calcium intake in early adulthood can increase the rate of calcium gain in bone. In this study, we investigated the association of bone health-related nutritional knowledge levels with calcium-related dietary behavior and nutrition education among women. Data were collected using questionnaires from 347 women aged 20~30 residing in Gyeonggi-do. Subjects were categorized into two groups according to their bone health-related nutritional knowledge (high or low-knowledge group). Knowledge related to bone health and calcium, and dietary habits was assessed, and the preference for and intake frequency of calcium-rich food were collected and analyzed using food frequency questionnaires. The high-knowledge group showed a significantly higher rate of nutritional education experience (33.9%) when compared with the low-knowledge group (18.9%). Not only were the perceptions regarding milk and dairy products more positive in the high-knowledge group (P<0.05), but the intake frequency of calcium-rich foods, such as tofu, soybean, and anchovies, was also higher in this group compared to the low-knowledge group (P<0.05). Overall, the preference for all calcium-rich foods was positively correlated to their intake frequency (P<0.05). Nutrition education experience and the recognition of the need for such education were positively correlated with the bone health-related nutrition knowledge score (P<0.05). In conclusion, bone health-related nutritional knowledge can affect calcium-related dietary behavior and increase the intake of calcium-rich food of 20~30-year-old women and this can contribute to the prevention of osteoporosis. To improve bone health-related nutritional knowledge among young women, it may be important to provide nutrition education.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.5
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• pp.373-386
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• 2023

To analyze the prediction of geological conditions and water-bearing zones, TSP was performed in the collapse zone of the fault zone. The results of the TSP were verified by comparing them to the face mapping results of the prediction zone. The rock quality prediction result of the TSP had an error of about 3 to 10 meters compared to the face mapping result, but the overall rock quality change and ground condition were analyzed to be relatively similar. In the water-bearing zones of the face mapping results, the Vp/Vs ratio ranges from 1.79 to 2.37 and the Poisson's ratio ranges from 0.27 to 0.39. In the sections other than the water-bearing zones, the Vp/Vs ratio ranges from 1.61 to 1.89, and the Poisson's ratio ranges from 0.19 to 0.3. As a result of analyzing the Vp/Vs ratio and Poisson's ratio in the water-bearing zones, it is analyzed that the sections with a Vp/Vs ratio of 2.0 or more and a Poisson's ratio of 0.3 or more have a high possibility of being water-bearing zones.

• Clean Technology
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• v.15 no.3
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• pp.224-230
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• 2009

Life Cycle Assessment (LCA) has been studied on the reuse of glass bottles. The system boundary in this study encompassed from gate to gate such as production and transportation. A 360 mL volume of a glass bottle was selected as the functional unit. The environmental impact assessments was studied on 6 categories including abiotic resource depletion, acidification, eutrophication, global warming, ozone depletion, and photochemical oxidant creation. The results showed that the most significant impact categories were abiotic resource depletion (48.63%) and global warming (46.27%), and the rest categories revealed insignificant impacts. In the whole system, the chemicals used for the new bottle production revealed the major contribution to the environmental impacts (71.24%), followed by the use of electricity (16.74%) and transportation (11.8%). In addition, the environmental impact of sodium silicate to be put into the stage of the new bottle production was found to be 45.68%, causing severe influence on abiotic resource depletion and global warming.