• Journal of Wetlands Research
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• v.23 no.1
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• pp.85-93
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• 2021

Sewage separation which often involves installing a new pipe to separate wastewater flow from stormwater runoff flow can be costly and depends highly on its feasibility in a site. To be able to develop a potentially more economical alternative that can also lessen major road traffic disturbance during this process, a different approach where a smaller sewage separator pipe is installed inside an existing combined sewer pipe was investigated. A small-scale of a box sewer and the proposed sewage separator pipe was constructed in the laboratory to observe and compare the deposition of solids and other solid-associated major pollutants at different flow rates. In addition, three-dimensional flow simulations considering five different scenarios were conducted using Ansys Fluent to observe the effect of the proposed sewage separator pipe to the hydraulic flow if installed inside the combined sewer pipe. Results revealed that the deposition of TSS, TCOD, TN, and TP were reduced by at least 60% when the wastewater was conveyed by the sewage separator pipe instead of the combined sewer pipe. Moreover, the flow simulations conducted showed that there was little to no major disturbance in hydraulic flow and velocity distribution when the sewage separator was installed inside a straight pipe and even at pipe transitions such as intersections, turns, and drop in elevation. Considering the pipe dimensions and the results of the study, the proposed approach can be promising in terms of reduction in pollutant deposition without a major effect on the hydraulic flow. Further investigation and cost-analysis should be done in the future to support these preliminary findings and help alleviate the problems caused by combined sewer overflows by introducing an alternative approach.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.12
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• pp.963-969
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• 2021

The wind data measured from local meteorological masts is used to evaluate wind speed distribution and energy production in the specified site for wind farm However, wind data measured from meteorological masts often contain missing information or insufficient desired height or data length, making it difficult to perform wind turbine control and performance simulation. Therefore, long-term continuous wind data is very important to assess the annual energy production and the capacity factor for wind turbines or wind farms. In addition, if seasonal influences are distinct, such as on the Korean Peninsula, wind data with seasonal characteristics should be considered. This study presents methodologies for generating synthetic wind that take into account fluctuations in both wind speed and direction using the hidden Markov model, which is a statistical method. The wind data for statistical processing are measured at Maldo island in the Kokunnsan-gundo, Jeonbuk Province using the Automatic Weather System (AWS) of the Korea Meteorological Administration. The synthetic wind generated using the hidden Markov model will be validated by comparing statistical variables, wind energy density, seasonal mean speed, and prevailing wind direction with measurement data.

• Journal of Korea Water Resources Association
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• v.55 no.7
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• pp.531-543
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• 2022

Integrated water resources management (IWRM) has focused on efficient response to various water related disasters by climate change. In particular, more flexible usage of conventional water resources infrastructures is expected to provide an eco-friendly water management. Multi-purpose dams and water supply dams are well known as water management facilities for securing and supplying water in drought season. Recently, based on the report '2021 multi-purpose use of hydropower dams in Han river', contribution of hydropower dams on water resources management is becoming more significant beyond the traditional role of hydropower generation. In drought conditions, the dams control water supply depending on the pre-defined drought stages. In the case of multi-purpose dams, an operation standard during drought has been already prepared and applied; however, for the hydropower dams, specific standards are not fully prepared yet in South Korea. In this study, a method for calculation of standard water storage and discharge reduction of hydropower dams according to drought stage is newly proposed reflecting the characteristics of hydropower dams. The proposed method was applied to the hydropower dams in Han river, where six hydropower dams are located. A case study of the historical droughts occurred in 2014-2017 demonstrated that the proposed hydropower dam operation rule could improve the water supply stability under severe drought conditions compared to the conventional operations. In the future, the role of hydropower dams for water resources management is expected to become more important, and this study can be widely used for water supply planning such as drought response using hydropower dams.

• Parasites, Hosts and Diseases
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• v.60 no.4
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• pp.241-246
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• 2022

Felids are the unique definitive host of Toxoplasma gondii. The intestine of felid is the only site for initiating Toxoplasma gondii sexual reproduction. T. gondii excretes millions of infectious oocysts from the intestine, which are the primary source of infection. There are many difficulties in developing vaccines and drugs to control oocyst excretion due to the lack of an appropriate experimental model. Here, we established an in vitro feline intestinal epithelial cell (IEC) infection system and an efficient animal model of T. gondii Chinese 1 genotype, Wh6 strain (TgCtwh6). The Kunming mice brain tissues containing TgCtwh6 cysts were harvested 42-day post-infection. The bradyzoites were co-cultured with cat IECs in vitro at a ratio of 1:10. Five 3-month-old domestic cats were orally inoculated with 600 cysts each. The oocysts were detected by daily observation of cat feces by microscopy and polymerase chain reaction. We found that the parasite adhered and invaded cat IECs in vitro, transformed into tachyzoites, and then divided to form rose-like structures. These parasites eventually destroyed host cells, escaped, and finished the asexual reproduction process. Schizonts associated with sexual reproduction have not been observed during development in vitro cultured cells. However, schizonts were detected in all infected cat intestinal epithelial cells, and oocysts were presented in all cat feces. Our study provides a feasible cell model and an efficient infection system for the following studies of T. gondii sexual reproduction, and also lays a foundation to develop drugs and vaccines for blocking excretion and transmission of oocysts.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.91-96
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• 2021

The enhancement of thermoelectric figure of merit was achieved by the simple processes of sieving and high energy ball milling, respectively, which are enable to reduce the grain size of n-type Bi₂Te₃ thermoelectric materials. By optimizing the grain size, the electrical conductivities and thermal conductivities were controlled. In this study, spark plasma sintering was employed for hindering the grain growth during the sintering process. The thermoelectric figure of merit was measured to be 0.78 in the samples with 30 min high energy ball milling process. Notably, this value was 40 % higher than that of pristine Bi₂Te₃ sample. This result shows the properties of thermoelectric materials can be readily controlled by optimization of grain size via simple ball milling process.

• Journal of Appropriate Technology
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• v.6 no.2
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• pp.136-145
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• 2020

Agriculture is the backbone of the economy of most developing countries. In these countries, agriculture or farming is mostly done manually with little integration of machinery, intelligent systems and data monitoring. Irrigation is an essential process that directly influences crop production. The fluctuating amount of rainfall per year has led to the adoption of irrigation systems in most farms. The absence of smart sensors, monitoring methods and control, has led to low harvests and draining water sources. In this research paper, we introduce a 433 MHz Radio Frequency and 2G based Smart Irrigation Meter System and a water prepayment system for rural areas of Tanzania with no reliable internet coverage. Specifically, Ngurudoto area in Arusha region where it will be used as a case study for data collection. The proposed system is hybrid, comprising of both weather data (evapotranspiration) and soil moisture data. The architecture of the system has on-site weather measurement controllers, soil moisture sensors buried on the ground, water flow sensors, a solenoid valve, and a prepayment system. To achieve high precision in linear and nonlinear regression and to improve classification and prediction, this work cascades a Dynamic Regression Algorithm and Naïve Bayes algorithm.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.650-657
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• 2020

Purpose: In this study, the effectiveness of pilot project of PLSP (Priority Lane and Signal Preference) system, which was operated in Cheongju City, was analyzed. Method: The priority signal was operated by a police officer switching to a blue signal when approaching a fire truck through CCTV, and the priority lane of emergency vehicles was displayed on the road to enable preferential traffic. VISSIM simulation analysis was performed for the 1.2km section (3.8km) of the pilot project section and vehicle data was analyzed for some of the test operation sections. Result: Simulation analysis shows that the moving speed of the emergency vehicle can be increased by 42 km/h with the introduction of PLSP, which can be increased by approximately twice the speed. Travel time was reduced by about 3 minutes, and considerable improvements of 69% compared to cities that are not operating was analyzed. The pilot operation of Cheongju City showed a time-shortening effect of about two minutes on average, with the average time reaching 4 minutes and 14 seconds in the first period and the average time reaching 5 minutes and 40 seconds in the second period. Conclusion: The system has been shown to be effective in minimizing time-to-site arrival of emergency vehicles.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.935-942
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• 2022

In doing interventional treatment under the guidance of ultrasonography, the medical team detects the legion site with ultrasonic equipment at first, and insert angio needle. In this situation, if the position of legion and the depth of inserted needle on the ultrasonographic screen are different from real position and depth, the needle is likely to damage a major blood vessel or tissue. Accordingly, we had wondered how much such differences between screen image and reality, and so decided to examine them. Using five ultrasonographic equipments manufactured from different companies in different years, this study tried to compare the lengths of the needle on the screen images and real lengths of it, and find out the factors affecting skewness of them. This study used hog meat chunk to mimic human flesh, and sausages as the target of needle. It compared penetrating depths of the needle as the images on the five equipments using single sample t test in the SPSS 22 statistical program. It was found that all the errors were statistically significant(<.05). So, this study decided that it was wrong to evaluate performances of the equipments by the makers and ages of them. It is necessary to do periodic quality controls of equipments and improve the skillfulness of sonographers to reduce error rates between real treatment areas and the images of them.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.6
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• pp.51-64
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• 2022

Along with the urbanization, the risk of urban flooding due to climate change is increasing. Flood regulation, one of the ecosystem services, is implemented in the different level of function of flood risk mitigation by the type of ecosystem such as forests, arable land, wetlands etc. Land use changes due to development pressures have become an important factor in increasing the vulnerability by flash flood. This study has conducted evaluating the urban flood regulation service using InVEST UFRM(Urban Flood Risk Model). As a result of the simulation, the potential water retention by ecosystem type in the event of a flash flood according to RCP 4.5(10 year frequency) scenario was 1,569,611 tons in urbanized/dried areas, 907,706 tons in agricultural areas, 1,496,105 tons in forested areas, 831,705 tons in grasslands, 1,021,742 tons in wetlands, and 206,709 tons in bare areas, the water bodies was estimated to be 38,087 tons. In the case of more severe 100-year rainfall, 1,808,376 tons in urbanized/dried areas, 1,172,505 tons in agricultural areas, 2,076,019 tons in forests, 1,021,742 tons in grasslands, 47,603 tons in wetlands, 238,363 tons in bare lands, and 52,985 tons in water bodies. The potential economic damage from flood runoff(100 years frequency) is 122,512,524 thousand won in residential areas, 512,382,410 thousand won in commercial areas, 50,414,646 thousand won in industrial areas, 2,927,508 thousand won in Infrastructure(road), 8,907 thousand won in agriculture, Total of assuming a runoff of 50 mm(100 year frequency) was estimated at 688,245,997 thousand won. In a conclusion. these results provided an overview of ecosystem functions and services in terms of flood control, and indirectly demonstrated the possibility of using the model as a tool for policy decision-making. Nevertheless, in future research, related issues such as application of models according to various spatial scales, verification of difference in result values due to differences in spatial resolution, improvement of CN(Curved Number) suitable for the research site conditions based on actual data, and development of flood damage factors suitable for domestic condition for the calculation of economic loss.

• Journal of Korean Neurosurgical Society
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• v.65 no.2
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• pp.224-235
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• 2022

Objective : Since the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, neurointerventionists have been increasingly concerned regarding the prevention of infection and time delay in performing emergency thrombectomy procedures in patients with acute stroke. This study aimed to analyze the effects of changes in mechanical thrombectomy protocol before and after the COVID-19 pandemic on procedure time and patient outcomes and to identify factors that significantly impact procedure time. Methods : The last-normal-to-door, first-abnormal-to-door, door-to-imaging, door-to-puncture, and puncture-to-recanalization times of 88 patients (45 treated with conventional pre-COVID-19 protocol and 43 with COVID-19 protection protocol) were retrospectively analyzed. The recanalization time, success rate of mechanical thrombectomy, and modified Rankin score of patients at discharge were assessed. A multivariate analysis was conducted to identify variables that significantly influenced the time delay in the door-to-puncture time and total procedure time. Results : The door-to-imaging time significantly increased under the COVID-19 protection protocol (p=0.0257) compared to that with the conventional pre-COVID-19 protocol. This increase was even more pronounced in patients who were suspected to be COVID-19-positive than in those who were negative. The door-to-puncture time showed no statistical difference between the conventional and COVID-19 protocol groups (p=0.5042). However, in the multivariate analysis, the last-normal-to-door time and door-to-imaging time were shown to affect the door-to-puncture time (p=0.0068 and 0.0097). The total procedure time was affected by the occlusion site, last-normal-to-door time, door-to-imaging time, and type of anesthesia (p=0.0001, 0.0231, 0.0103, and 0.0207, respectively). Conclusion : The COVID-19 protection protocol significantly impacted the door-to-imaging time. Shortening the door-to-imaging time and performing the procedure under local anesthesia, if possible, may be required to reduce the door-to-puncture and door-to-recanalization times. The effect of various aspects of the protection protocol on emergency thrombectomy should be further studied.