• Journal of Cardiovascular Imaging
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• v.30 no.1
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• pp.50-58
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• 2022

BACKGROUND: Little is known regarding right ventricular (RV) remodeling immediately after Tetralogy of Fallot (TOF) repair. We sought to describe myocardial deformation by cardiac magnetic resonance imaging (CMR) after TOF repair and investigate associations between these parameters and early post-operative outcomes. METHODS: Fifteen infants underwent CMR without sedation as part of a prospective pilot study after undergoing complete TOF repair, prior to hospital discharge. RV deformation (strain) was measured using tissue tracking, in addition to RV ejection fraction (EF), volumes, and pulmonary regurgitant fraction. Pearson correlation coefficients were used to determine associations between both strain and CMR measures/clinical outcomes. RESULTS: Most patients were male (11/15, 73%), with median age at TOF repair 53 days (interquartile range, 13,131). Most patients had pulmonary stenosis (vs. atresia) (11/15, 73%) and 7 (47%) received a transannular patch as part of their repair. RV function was overall preserved with mean RV EF of 62% (standard deviation [SD], 9.8). Peak radial and longitudinal strain were overall diminished (mean ± SD, 33.80 ± 18.30% and -15.50 ± 6.40%, respectively). Longer hospital length of stay after TOF repair was associated with worse RV peak radial ventricular strain (correlation coefficient (r), -0.54; p = 0.04). Greater pulmonary regurgitant fraction was associated with shorter time to peak radial RV strain (r = -0.55, p = 0.03). CONCLUSIONS: In this small study, our findings suggest presence of early decrease in RV strain after TOF repair and its association with hospital stay when changes in EF and RV size are not yet apparent.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.301-312
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• 2016

This study has performed comparative analysis on characteristics of contaminated 35 tributaries on seasonal variation/point discharge load/pollutant distribution of water quality factors(8) in order to understand the effect of the watershed in Nakdong River Basin. As a results, the water quality of $BOD_5$(Biochemical Oxygen Demand), Chl-a(Chlorophyll a) and Fecal E. Coli shows II grade at tributaries of more than 50% without COD(Chemical Oxygen Demand), TP(Total Phosphate), TOC(Total Oxygen Carbon) and TN(Total Nitrogen) factors. The specific discharge(Q) were occupied about 54.4% (19 sites) as $0.05m^3/sec/km^2$ value. Among these results, the contaminant level of Dalseocheon, Hyeonjicheon, Seokkyocheon 1, Uriyeongcheon and Dasancheon was also high, which has to consider a discharged pollutant load(kg/day). The 35 major tributaries of Nakdong River were included in 7 mid-watershed, such as Nakdong Waegwan, Geumho River, Nakdong Goryung, Nakdong Changnyung, Nam River, Nakdong Milyang, Nakdong River Hagueon. Especially, the discharged pollutant load of Nam River and Geumho River also was high according to the amount of discharge such as Kachang dam, Gongsan dam and Nam river dam. Seasonal difference of the water quality factors such as $BOD_5$, TN, SS and Q was observed largely, on the other hand the TP and Chl-a was not. This is guessed due to the precipitation effect of site, biological and physicochemical degradation properties of pollutant and etc. The co-relationship between the seasonal difference and water quality factors was observed using a Pearson correlation coefficients. Besides, the Multiple Regression analysis using a Stepwise Regression method was conducted to understand the effect between seasonal difference and water quality factors/regression equations. As a result, the Multiple Regression analysis was adapted in the spring, summer and autumn without the winter, which was observed high at spring, summer and autumn in the order COD/TP, Chl-a/TOC, TOC/COD/$BOD_5$ water quality factors, respectively.

• Nuclear Engineering and Technology
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• v.18 no.3
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• pp.200-208
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• 1986

The loss of coolant accident based on a double-ended cold leg break is analyzed with the discharge coefficient (Ca) of 0.4. This analysis covers the whole transient period from the start of depressurization to the complete refilling of the core by using RELAP4/MOD6-EM and RELAP4/ MOD6-HOT CHANNEL for the system thermal-hydraulics and the fuel performance during the blowdown phase respectively, and RELAP4/MOD6-FLOOD and TOODEE2 during the reflood phase. A simple analytical method has been developed to account for the lower plenum filling by approximating steam-water countercurrent flows and superheated wall effects at the downcomer during the refill period. Based on the informations. at the time of EOB (end-of-bypass), the refill duration time and the initial reflooding temperature were estimated and compared with the results from the RELAP4/MOD6, resulting in a good agreement. In addition, some parametric studies on the EOB were performed. The form loss coefficient between upper head and upper downcomer was found to be sensitive to the occurrence of the spurious EOB. Appropriate form loss coefficients should be taken into account to avoid the flow oscillations at the downcomer. The analyses with the six and three volume core nodalizations, respectively, show much similar trends in the system thermal-hydraulic performance, but the former case is recommended to obtain good results.

• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.139-145
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• 2001

Various compositions of iron oxide based materials as a cathode of lithium secondary battery have been fabricated and tested with electrochemical method. A layered form of $LiFeO_2$ was synthesized by mixing and heating the initial materials of $FeCl_3\;6H_2O,\;LiOH$ and NaOH at low temperature. The effect of changing the precursors composition was investigated. As a result, when increasing the additive amount of NaOH, the capacity of the electrode is decreased but the performance and declining rate of capacity became smaller. $LiFeO_2$ synthesized with the weight ratio of $NaOH/FeCl_3/LiOH,\;2/1/7$ showed the largest capacity, but the discharging efficiency was sharply decreased after 30 cycles. Charge-discharge tests of lithium cells with $LiFeO_2$ cathode having the layer structure were performed. This cell showed the reversibility in the range of 1.5-4.5V of cell voltage. By using CPR method, chemical diffusion coefficients were measured in 1M $LiPF_6/EC/DEC$ solution. The value of chemical diffusion coefficient decreased with increasing the lithium content x, In 0.5$10^{-11}^cm^2/s$.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.160-174
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• 2014

The purpose of this paper is to develop a meso-scale grid-based continuous hydrological model and apply to assess the future watershed hydrology by climate change. The model divides the watershed into rectangular cells, and the cell profile is divided into three layered flow components: a surface layer, a subsurface unsaturated layer, and a saturated layer. Soil water balance is calculated for each grid cell of the watershed, and updated daily time step. Evapotranspiration(ET) is calculated by Penman-Monteith method and the surface and subsurface flow adopts lag coefficients for multiple days contribution and recession curve slope for stream discharge. The model was calibrated and verified using 9 years(2001-2009) dam inflow data of two watersheds(Chungju Dam and Soyanggang Dam) with 1km spatial resolution. The average Nash-Sutcliffe model efficiency was 0.57 and 0.71, and the average determination coefficient was 0.65 and 0.72 respectively. For the whole Han river basin, the model was applied to assess the future climate change impact on the river bsain. Five IPCC SRES A1B scenarios of CSIRO MK3, GFDL CM2_1, CONS ECHO-G, MRI CGCM2_3_2, UKMO HADGEMI) showed the results of 7.0%~27.1 increase of runoff and the increase of evapotranspiration with both integrated and distributed model outputs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.311-324
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• 2017

Energy loss at manholes under surcharged flow is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze the flow characteristics to reduce the energy loss in the surcharged four-way combining manhole. In this study, hydraulic experimental apparatus was constructed considering the results of the present survey. Square manholes and pipe diameters were reduced to 1/5 by applying sewer facility standards. Numerical simulations were carried out with the Fluent 6.3 model to derive the invert condition which can reduce the energy loss in the surcharged four-way combining square manhole. The hydraulic experiments were carried out according to the various conditions of the lateral flow rate($Q_{lat}/Q_{out}$), discharge of outflow pipe (2.0, 3.0, 4.0, 4.8 l/sec), and invert shape (rectangle and square open conduit type). The crossed invert was not found to improve the drainage capacity of the surcharged four-way rectangular combining manhole. However, the improved rectangle open conduit type invert and square open conduit type invert were analyzed to improve the drainage capacity by reducing the head loss coefficients by about 8% and 28%, respectively. Therefore, in order to increase the drainage capacity of urban facilities, it is possible to install and use the improved invert proposed in this study.

• Economic and Environmental Geology
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• v.37 no.6 s.169
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• pp.631-645
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• 2004

This study assesses groundwater vulnerability to contaminants in industrial and residential/commercial areas of the city of Changwon, using DRASTIC technique and groundwater data. The DRASTIC technique was originally applied to situations in which the contamination sources are at the ground surface, and the contaminants flow into the groundwater with infiltration of rainfall. Mostly the industrial area has higher DRASTIC indices than the residential/commercial area. However, a part of the residential/commercial area having much groundwater production and great drawdown is more contaminated in groundwater than other industrial and the residential/commercial areas even if it has lowest DRASTIC indices in the study area. It indicates that groundwater contamination in urban areas can be closely related to excessive pumping resulting in a lowering of the water level. The correlation coefficient between minimum DRASTIC indices and the degree of poor water quality for 10 districts is as low as 0.40. On the other hand, the correlation coefficients between minimum DRASTIC indices and the groundwater discharge rate, and between minimum DRASTIC indices and well distribution density per unit area are 0.70 and 0.87, respectively. Thus, to evaluate the potential of groundwater contamination in urban areas, it is necessary to consider other human-made factors such as groundwater withdrawal rate and well distribution density per unit area as well as the existing seven DRASTIC factors.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.4
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• pp.274-281
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• 2015

Thermal and nuclear power plants on shore commonly use the sea water for cooling facility. Discharged cooling water has the high kinematic energy potential due to amount of water flux. Numerical analysis was made to find the suitable combinations between the arrangement of tidal turbines and the overall dimensions of the discharged channel. Several parameters such as the turbine diameter to inlet size, and the axial distance to turbine size were investigated. Power coefficients for various test conditions were also compared to see the effect of inlet configurations such as single inlet and dual inlet. For the single inlet, the mean power coefficient appeared to be gradually decreased with increasing distance, and the maximum power was obtained when the turbine diameter was same as the inlet diameter. For the dual inlet, the tendency was similar so that the better result when the turbine diameter was same as the inlet diameter. It is expected that the present methodology can be extensively utilized to harness the high kinetic energy flow of the discharge channel of power plant.

• Journal of Korea Water Resources Association
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• v.47 no.10
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• pp.867-878
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• 2014

Due to the nature of weather radar, blank areas occur due to impediments to observation, such as the ground clutter. Radar beam blockages have resulted in the underestimation rainfall amounts. To overcome these limitations, this study developed the Hybrid Scan Reflectivity (HSR) technique and compared the HSR results with existing methods. As a result, the HSR technique was able to estimate rainfalls in areas from which no reflectivity information was observable using existing methods. In case of estimating rainfalls depending on reflectivity scan techniques and beam-blockage/non beam-blockage, the HSR accuracy is superior. Furthermore, rainfall amounts derived from each method was inputted to the HEC-HMS to examine the accuracy of the flood simulations. The accuracy of the results using the HSR technique in contrast to the RAR calculation system and M-P relation was improved by 7% and 10%(based on correlation coefficients), and 18% and 34%(based on Nash-Sutcliffe Efficiency), on average, respectively. Therefore, it is advised that the HSR technique be utilized in the hydrology field to estimate flood discharge more accurately.

• Journal of Home Health Care Nursing
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• v.8 no.2
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• pp.135-147
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• 2001

The aim of this descriptive study was to identify the impact of chronic illness on children and their families. Mothers of 177 children with chronic disease were recruited from aged one to 17 years hospitalizing the pediatric nursing unit at one university hospital. 28 questions. a self-complete maternal questionnaire developed by researchers based on literatures and 'The Impact of Childhood Illness Scale' (Hoare & Russell, 1995) assess four aspects of the child's and family's lifestyle with two dimensions for each question. the frequency of the problem and its importance of concern that it cause. In the data analysis. Pearson correlation coefficients and analysis of variance were used to test any association and a statistical comparisons. between individual variables and the impact on child's and family's lifestyle. The results were as follows: 1) There were the higher mean scores on the importance dimension than on the frequency dimension on total impact on child's and family's lifestyle. On the importance dimension. mothers had much higher levels of concern about impact on child's development and adjustment among subscales. On the frequency dimension, mothers had much higher levels of concern about impact on the family daily living on subscales. 2) The impact on child's and family's lifestyle related on individual variables were: (1) On the importance dimension. there was statistically significant low in the impact on child's development and adjustment among subscales in older parent group compared with it of younger parent group. (2) On the frequency dimension. there were statistically significant high in the impact on child's development and adjustment among subscales in the children with leukemia or cancer compared with it of the other children who had another chronic illnesses. And there were statistically significant high in the impact on child's development and adjustment among subscales in less than high school educated mothers compared with it of mothers who was educated college level. (3) On the frequency dimension. There were statistically significant high in the impact on family's daily living among subscales and total impact on child's and family's lifestyle in female children. (4) There was positive correlation between impact on parents daily living and frequency of child's hospitalization on the frequency dimension. but there was negative correlation between the two variables on the importance dimension. (5) There was positive correlation between impact of chronic illness and its treatment and duration of child's hospitalization on the frequency dimension. In conclusion. these results were reflected by the high level of concerns about impact on child's development and adjustment although mothers had frequently responded about the impact on the family daily living. We suggest consistent intervening program that help the family empowering to make children live with and adjust to their chronic illnesses from the point of diagnosis and after discharge from the hospital. We also suggest these results can be utilized as a useful data in the practice of home health nursing for children who have chronic illnesses and their families.