• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.634-645
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• 2011

A newly developed rainwater harvesting (RWH) system reliability model is evaluated for roof area of buildings in Haeundae District of Busan. RWH system is used to supply water for toilet flushing, back garden irrigation, and air cooling. This model is portable because it is based on a non-parametric precipitation generation algorithm using a markov chain. Precipitation occurrence is simulated using transition probabilities derived for each day of the year based on the historical probability of wet and dry day state changes. Precipitation amounts are selected from a matrix of historical values within a moving 30 day window that is centered on the target day. Then, the reliability of RWH system is determined for catchment area and tank volume ranges using synthetic precipitation data. As a result, the synthetic rainfall data well reproduced the characteristics of precipitation in Busan. Also the reliabilities of RWH system for each of demands were computed to high values. Furthermore, for study area using the RWH system, reduction efficiencies for rooftop runoff inputs to the sewer system and potable water demand are evaluated for 23%, 53%, respectively.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.3
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• pp.122-127
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• 2021

Flow features near the ship bow such as wave breaking, small scale phenomena have been studied using numerical methods. In this study, the bow shaped wedge was adopted which is from previous paper [1, 2] and the conditions of simulation were Re = 1.64 × 10⁵) and Fr = 2.93. Star CCM+, one of the commercial CFD programs has been used for the simulations. Simulation results such as wave profiles near the ship bow, shape of plunging jet, air entrainment, and wave breaking process have been compared with previous experimental and numerical studies. Overall results showed good agreements with previous studies. Profiles of bow waves showed that overturning jet has been created and broken along the wedge. Plunging wave breaking has been observed along the wedge and four components of plunging wave breaking process were shown. It is confirmed that velocity near the overturing jet significantly increased during plunging wave breaking.

• Journal of Yeungnam Medical Science
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• v.39 no.3
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• pp.223-229
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• 2022

Background: The first large coronavirus disease 2019 (COVID-19) outbreak outside China occurred in Daegu. In response, we developed infection prevention measures for surgical patients during the outbreak at our hospital and retrospectively reviewed the outcomes of COVID-19-related surgical patients. Methods: We reviewed the medical records of 118 COVID-19-related surgical patients and monitored their clinical outcomes until March 31, 2021. We also interviewed healthcare workers who participated in their perioperative care at Kyungpook National University Chilgok Hospital. The perioperative management guidelines for COVID-19-related patients were prepared through multidisciplinary discussions, including the infection control department, surgical departments, and anesthesiology department before and during the COVID-19 outbreak. Results: One standard operating room was temporarily converted to a negative-pressure room by increasing the exhaust air volume, creating a relative pressure of -11.3 Pa. The healthcare workers were equipped with personal protective equipment according to the patient's classification of the risk of COVID-19 transmission. The 118 COVID-19-related patients underwent emergent surgery in the negative-pressure room, including three COVID-19-confirmed patients and five COVID-19-exposed patients. Conclusion: All surgeries of the COVID-19-related patients were performed without specific adverse events or perioperative COVID-19 transmission. Our experience setting up a negative-pressure operating room and conservative perioperative protocol to prevent COVID-19 transmission will help plan and execute infection control measures in the future.

• Journal of People, Plants, and Environment
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• v.24 no.2
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• pp.195-207
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• 2021

Background and objective: While response measures to particulate matters in rural areas are limited due to poor inventory record keeping in the agricultural sector, it is necessary to control agricultural waste vinyl and the emission of precursors released from open burning and the secondary generation of particulate matters. Currently, the open burning emission calculation method uses the definition prescribed in CAPSS by the National Institute of Environmental Research. Methods: This study presented an open burning emission calculation formula for agricultural waste vinyl, which is included as agricultural waste. As for activity data, the open burning ratio of agricultural waste vinyl, and the annual incineration volume provided in the Status Survey by the Ministry of Agriculture, Food, and Rural Affairs were applied. The emission factor was generated through incineration tests on three agricultural plastic film samples collected by the Korea Environment Corporation. Results: Among precursors, SOx and NOx were selected and their emission features were monitored with incineration experiment infrastructure based on the EPA 5G method. The highest emission concentration by agricultural waste type was concentrated in the first and second quarters. As for emission factor of SO₂, it was calculated at 98.25 g/kg for mulching-use LDPE, 52.31 g/kg for greenhouse-use LDPE, and 14.40 g/kg for HDPE. As for NOx, it was calculated at 18.21 g/kg for mulching-use LDPE, 16.49 g/kg for greenhouse-use LDPE, and 10.67 g/kg for HDPE. Conclusion: This test confirmed the incineration features of PE-based plastics, ascertained the SOx emission factor that had not been included in open burning in the past, and established that low NOx emission concentration is interfered by soil mixed with livestock excretions. The findings from this study are expected to contribute to improving the system for controlling air pollutants in rural environments.

• Korean Journal of Environmental Agriculture
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• v.41 no.2
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• pp.101-107
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• 2022

BACKGROUND: Soil amendment was necessary applied for the sand that had been used to root zone of green ground in golf course because of its low water retention power and cation exchangeable capacity. This study was conducted to evaluate the effect of the mixed ratio of peat moss and coconut coir as soil amendment materials on the soil physicochemical properties applied to rootzone based on sand. METHODS AND RESULTS: The soil amendments were blended at 0, 3, 5, 7 and 10% by soil volume. The pH in the peat moss treatment was lower than that of control (0% soil amendment), and pH and electrical conductivity (EC) in the coconut coir were higher. The blending ratio of peat moss was negatively correlated with pH of rootzone soil (p<0.01), and that of coconut coir positively with EC (p<0.01). As compared with control, capillary porosity, the physical factors such as air-filled porosity, total porosity, and hydraulic conductivity of rootzone soil were increased by applying peat moss and coconut coir. For correlation coefficients between percentage of soil amendments and soil physical factors, peat moss and coconut coir were positively correlated with porosity and hydraulic conductivity (p<0.01). CONCLUSION(S): These results indicated that the application of peat moss and coconut coir affected on the change of physicochemical properties of rootzone soil, and improved soil porosity and hydraulic conductivity.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.861-866
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• 2022

Seoul introduced the shared bicycle system, "Seoul Public Bike" in 2015 to help reduce traffic volume and air pollution. Hence, to solve various problems according to the supply and demand of the shared bicycle system, "Seoul Public Bike," several studies are being conducted. Most of the research is a strategic "Bicycle Rearrangement" in regard to the imbalance between supply and demand. Moreover, most of these studies predict demand by grouping features such as weather or season. In previous studies, demand was predicted by time-series-analysis. However, recently, studies that predict demand using deep learning or machine learning are emerging. In this paper, we can show that demand prediction can be made a little better by discovering new features or ordering the importance of various features based on well-known feature-patterns. In this study, by ordering the selection of new features or the importance of the features, a better coefficient of determination can be obtained even if the well-known deep learning or machine learning or time-series-analysis is exploited as it is. Therefore, we could be a better one for demand prediction.

• Land and Housing Review
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• v.13 no.2
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• pp.117-123
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• 2022

In this study, titanium dioxide photocatalyst was applied to the ventilation system to reduce particulate matter and nitrogen oxides (NOx), which are representative indoor harmful substances. A reaction device capable of installing an ultraviolet lamp was designed and manufactured so that the pollutant decomposition effect of the titanium dioxide photocatalyst identified through previous studies could be applied indoors. The reaction device was used on the indoor ventilation system and applied to the Mock-Up test. As a result of the Mock-up test, the NOx reduction performance according to the change in air volume once per hour and five times per hour was confirmed. As a result, it was confirmed that as the number of ventilation increases, the NOx reduction time decreases proportionally, and the reduction performance increases.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.25-31
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• 2023

In this study, the basic properties of CO₂ immobilized desulfurized gypsum (CFBG) and the possibility of being used as a stimulus for slag cement were reviewed, and performance evaluation was conducted through a concrete mixing test. The main components of CFBG were CaO and SO₃, and CaO and SO₃ increased as the drying temperature increased. The moisture content of undried CFBG was 15.7 %, the drying temperature was 1.7 % and the drying temperature was 0.03 % at 105 ℃. Mortar using CFBG tended to have a lower flow value as the drying temperature increased, and the compressive strength was equivalent to that of the FGB use mixture. As a result of the concrete experiment using CFBG SC, both slump and air volume satisfied the target range after 60 minutes, and the compressive strength tended to increase overall compared to the ternary binder mixture.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.3
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• pp.57-63
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• 1986

Atmospheric particulate matter (A.P.M.) was collected on quartz fiber filters from March 1985 to May 1986 according to particle size using Andersen high-volume air sampler, and 6 heavy metals (Fe, Mn, Cu, Ni, Zn, Pb) in these particulates were analyzed by atomic absorption spectrophotometry. The arithmetic mean concentration of A.P.M. was 195.57$\mug/m^3$. The arithmetic mean concentrations of 6 metals (Fe, Mn, Cu, Ni, Zn and Pb) were 3385.04, 1451.67, 897.94, 159.68, 127.14 and 59.49 $ng/m^3$ respectively. The order of heavy metals contributing to A.P.M. was as follows: Fe > Zn > Pb > Cu > Mn > Ni. These heavy metals were devided into 3 groups according to their particle size distribution. The contents of heavy metals belonging to the 1st group (Fe, Mn) were increased with the particle size. On the contrary, the content of Pb belonging to the 2nd group (Pb) was increased with the decrease in the particle size. The heavy metal contents in the 3rd group (Ni, Cu, Zn) were lowest in the particle size range of 2.0-3.3 $\mum$ compared with particles larger or smaller tha this range. The seasonal variation of heavy metal concentration were as follows: Fe and Mn contents were highest in spring, but Ni and Pb contents were highest in winter. Statistical analysis showed that there was a significant correlation between A.P.M. and Fe in coarse particles, meanwhile between A.P.M. and Pb in the case of fine particles.

• Advances in nano research
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• v.15 no.1
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• pp.1-13
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• 2023

Ti₃C₂T_x MXene, a 2D material, is known to exhibit unique characteristics that are strongly dependent on surface termination groups. Here, we developed a novel annealing approach with Ca as a reducing agent to simultaneously remove F and O groups from the surface of multilayered MXene powder. Unlike H₂ annealing that removes F effectively but has difficulty in removing O, annealing with Ca effectively removed both O and F. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy revealed that the proposed approach effectively removed F and O from the MXene powder. The results of O/N analyses showed that the O concentration decreased by 57.5% (from 2.66 to 1.13 wt%). In addition, XPS fitting showed that the volume fraction of metal oxides (TiO₂ and Al₂O₃) decreased, while surface termination groups (-O and -OH) were enhanced, which could increase the hydrophilic and adsorption properties of the MXene. These findings suggest that when F and O are removed from the MXene powder, the interlayer spacing of its lattice structure increases. The proposed treatment also resulted in an increase in the specific surface area (from 5.17 to 10.98 m²/g), with an increase in oxidation resistance temperature in air from ~436 to ~667 ℃. The benefits of this novel technology were verified by demonstrating the significantly improved cyclic charge-discharge characteristics of a lithium-ion battery with a Ca-treated MXene electrode.