• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.228-234
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• 2004

Dissolved air flotation (DAF), in which suspended solids are removed from water by means of micro-size air bubbles raising slowly up in water and lifting solids from water (smaller than those) attached onto the micro-bubbles as well as those (larger than solids) being attached on these, have been used in water and wastewater since 1920s. The dissolved air flotation technology was originally based on the laminar flow conditions prevailing in water to be treated, but the latest development in that technology has led now to a situation, in which the flow conditions may also be turbulent ones in the modem dissolved air flotation units. Despite of that, the flotation phenomenon used in this unit operation for removal suspended solids from water or wastewater is still the same.

• Plant Journal
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• v.9 no.1
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• pp.36-42
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• 2013

In this study, repowering scenarios are analyzed and evaluated from the economical point of view on a case by case basis. Based on the result of evaluation, the IRR indicates 2.34% on single 750 MW LNG combined cycle unit, 3.56% on 500 MW sub-bituminous PC units and 2.31% on 200 MW circulating fluidized bed combustion units, resulting in not reaching 7% rate of discount rate and being concluded uneconomical. However, proposes that it is most economical and feasible to repower power plant into 750 MW LNG combined cycle unit as long as the economic feasibility can be improved and it is necessary for old anthracite power plant to be repowered than rebuilt under the circumstances of lacking power supply.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.2
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• pp.226-230
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• 1986

Two near-isogenic lines with dark and pale green leaves, derived from the F$\_$7/ generation of wxl26 cross were compared on photosynthetic capacity, growth parameters, grain yield and yield-related characters. Dark green-leaved lines contained much greater content of chlorophyll a and b than pale green-leaved ones, but chlorophyll a to b ratio showed no difference between them. The photosynthetic nte per unit leaf area was higher in dark green-leaved lines than in pale green-leaved ones in the flag leaves at heading stage, but that per unit chlorophyll content showed reversed result. The crop growth rate from transplanting to heading was consistantly higher in the dark green-leaved lines, resulting from their greater net assimilation rate. Dark green-leaved lines produced greater number of panicles and spikelets per hill, out yielding pale green-leaved lines, but ripened grain ratio and 1000-grain weight showed no differences between those lines.

• Journal of the Korean Solar Energy Society
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• v.30 no.3
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• pp.33-38
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• 2010

The evaporative desalination system using solar thermal energy would be the efficient and attractive method to get fresh water from brine due to low carbon dioxide generation. In this research the solar desalination system as a heating source of refrigerant R123 in the evaporator was considered. The circulation of refrigerant in the evaporator can reduce the energy consumption of the system, because of using the latent heat of the refrigerant 123 instead of the sensible heat of present hot water. The system was comprised of the single-stage fresh water production unit on the capacity of 1ton/day with shell and tube type evaporator, heaters instead of solar collector to supply the proper heat to refrigerant, and refrigerant and brine circulation systems. Various operating flowrate and temperature ranges were varied in the experiments to get the optimum design data. The results showed that the optimum flow rate of brine feed rate to evaporator was 1.2Liter/min, and the yield of fresh water was increased as higher temperature of feed brine. It was confirmed that the circulation flowrate of heating source of refrigerant was decrease of one fifth of the present warm water system, and very efficient system for solar desalination.

• Journal of Environmental Science International
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• v.18 no.1
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• pp.49-60
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• 2009

Fabrication and oxidants formation of 1 and 2 component metal oxide electrode, which is known to be so effective to destruct non-biodegradable organics in wastewater, were studied. Five electrode materials (Ru, Pt, Sn, Sb and Gd) were used for the 1 and 2 component electrode. The metal oxide electrode was prepared by coating the electrode material on the surface of the titanium mesh and then thermal oxidation at $500^{\circ}C$ for 1 h. The removed RhB per 2 min and unit W for one component electrode decreased in the following sequences: Ru/Ti>Sb/Ti>Pt/Ti>Gd/Ti>Sn/Ti. The concentration of oxidants generated in 1 and 2 component electrodes was in the order of: $ClO_2$> free Cl>$H_2O_2>O_3$. OH radical was not generated from in entire one and two component electrodes. RhB degradation rate and generated oxidants of the Ru-Sn=9:1 electrode was higher than that of the two component electrode. The exact relationship between the removal of RhB and the generated oxidants concentration was not obvious. However, it was assumed that electrode with high RhB decolorization had high oxidant concentration.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.297-304
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• 2022

The models used for ionosphere error correction in positioning using Global Navigation Satellite System (GNSS) are representatively Klobuchar model and NeQuick model. Although these models can correct the ionosphere error in real time, the disadvantage is that the accuracy is only 50-60%. In this study, a method for polynomial modeling of Global Ionosphere Map (GIM) which provides Vertical Total Electron Content (VTEC) in grid type was studied. In consideration of Ionosphere Pierce Points (IPP) of satellites with a receivable elevation angle of 15 degrees or higher on the Korean Peninsula, the target area for model generation and provision was selected, and the VTEC at 88 GIM grid points was modeled as a polynomial. The developed VTEC polynomial model shows a data reduction rate of 72.7% compared to GIM regardless of the number of visible satellites, and a data reduction rate of more than 90% compared to the Slant Total Electron Content (STEC) polynomial model when there are more than 10 visible satellites. This VTEC polynomial model has a maximum absolute error of 2.4 Total Electron Content Unit (TECU) and a maximum relative error of 9.9% with the actual GIM. Therefore, it is expected that the amount of data can be drastically reduced by providing the predicted GIM or real-time grid type VTEC model as the parameters of the polynomial model.

• Journal of Korean Neurosurgical Society
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• v.46 no.2
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• pp.123-129
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• 2009

Objective: This study was aimed to identify the incidence and risk factors of vancomycin-resistant enterococcus (VRE) colonization in neurosurgical practice of field, with particular attention to intensive care unit (ICU). Methods: This retrospective study was carried out on the Neurosurgical ICU (NICU), during the period from January. 2005 to December. 2007, in 414 consecutive patients who had been admitted to the NICU. Demographics and known risk factors were retrieved and assessed by statistical methods. Results: A total of 52 patients had VRE colonization among 414 patients enrolled, with an overall prevalence rate of 6.1%. E. faecium was the most frequently isolated pathogen, and 92.3% of all VRE were isolated from urine specimen. Active infection was noticed only in 2 patients with bacteremia and meningitis. Relative antibiotic agents were third-generation cephalosporin in 40%, and vancomycin in 23%, and multiple antibiotic usages were also identified in 13% of all cases. Multivariate analyses showed Glasgow coma scale (GCS) score less than 8, placement of Foley catheter longer than 2 weeks, ICU stay over 2 weeks and presence of nearby VRE-positive patients had a significantly independent association with VRE infection. Conclusion: When managing the high-risk patients being prone to be infected VRE in the NICU, extreme caution should be paid upon. Because prevention and outbreak control is of ultimate importance, clinicians should be alert the possibility of impending colonization and infection by all means available. The most crucial interventions are careful hand washing, strict glove handling, meticulous and active screening, and complete segregation.

• Journal of Sensor Science and Technology
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• v.14 no.1
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• pp.22-27
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• 2005

A thermoelectric flow sensor for small quantity of gas flow rate was fabricated using silicon wafer semiconductor process and bulk micromachining technology. Evanohm R alloy heater and chromel-constantan thermocouples were used as a generation heat unit and sensing parts, respectively. The heater and thermocouples are thermally isolated on the $Si_{3}N_{4}/SiO_{2}/Si_{3}N_{4}$ laminated membrane. The characteristics of this sensor were observed in the flow rate range from 0.2 slm to 1.0 slm and the heater power from 0.72 mW to 5.63 mW. The results showed that the sensitivities $(({\partial}({\Delta}V)/{\partial}(\dot{q}));{\;}{\Delta}V$ : voltage difference, $\dot{q}$ : flow rate) were increased in accordance with heater power rise and decreasing of flow rate.

• Journal of Radiation Protection and Research
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• v.44 no.4
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• pp.149-155
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• 2019

Background: Magnetic resonance (MR) image guided radiation therapy system, enables real time MR guided radiotherapy (RT) without additional radiation exposure to patients during treatment. However, MR image lacks electron density information required for dose calculation. Image fusion algorithm with deformable registration between MR and computed tomography (CT) was developed to solve this issue. However, delivered dose may be different due to volumetric changes during image registration process. In this respect, synthetic CT generated from the MR image would provide more accurate information required for the real time RT. Materials and Methods: We analyzed 1,209 MR images from 16 patients who underwent MR guided RT. Structures were divided into five tissue types, air, lung, fat, soft tissue and bone, according to the Hounsfield unit of deformed CT. Using the deep learning model (U-NET model), synthetic CT images were generated from the MR images acquired during RT. This synthetic CT images were compared to deformed CT generated using the deformable registration. Pixel-to-pixel match was conducted to compare the synthetic and deformed CT images. Results and Discussion: In two test image sets, average pixel match rate per section was more than 70% (67.9 to 80.3% and 60.1 to 79%; synthetic CT pixel/deformed planning CT pixel) and the average pixel match rate in the entire patient image set was 69.8%. Conclusion: The synthetic CT generated from the MR images were comparable to deformed CT, suggesting possible use for real time RT. Deep learning model may further improve match rate of synthetic CT with larger MR imaging data.

• Korea journal of population studies
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• v.5 no.1
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• pp.4-16
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• 1982

The Korean Population Control Program has been implementing under the jurisdiction of the Ministry of Health and Social Affairs through an existing network of health centers. This arrangement was successful in bringing population growth down to targeted level by the end of the Fourth Five Year Economic Planning, 1981. It is expected, however, that future goal will be harder to reach due to difficulty of reducing traditional family size norms further and to the projected increasing the number of eligible couples as the past Korean war baby boom generation enters the reproductive activity in the next few years. The recognition of the need for modification of population policy is increasing. The 1980 census shows that the total number of population reached approximately 38.5 million with 1.57 per cent of the growth rate. It was projected that the size of Korean Population will reach around 42 million and 51 million in 1986 and 2000 respectively. Furthermore, there is some argument as to whether decline in the birth rate in Korea is too slow to meet government target. Hence, a new development of population policy and greatly increased amount of effort will be needed in order to achieve Zero Population Growth Rate before the year 2050. The development of future national population policy and its related area are recommended as follow: 1. It is highly recommended that the population planning law governing both vital events of birth and death and population migration should be legislated. 2. The National Population Policy Council, Chaired by Deputy Prime Minister should be activated to implement and coordinate population program within ministries. 3. Responsible organization of population and family planning program should be established as a Bureau unit at central government level. 4. For the improvement of national vital registration, an existing system should be studied and developed.