• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.1-10
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• 2022

Irrigation water supplied to the paddy field is consumed in the amount of evapotranspiration, underground infiltration, and natural and artificial drainage from the paddy field. Irrigation return flow is defined as the excess of irrigation water that is not consumed by evapotranspiration and crop, and which returns to an aquifer by infiltration or drainage. The research on estimating the return flow play an important part in water circulation management of agricultural watershed. However, the return flow rate calculations are needs because the result of calculating return flow is different depending on irrigation channel water loss, analysis methods, and local characteristics. In this study, the irrigation return flow rate of agricultural watershed was estimated using the monitoring and SWMM (Storm Water Management Model) modeling from 2017 to 2020 for the Heungeop reservoir located in Wonju, Gangwon-do. SWMM modeling was performed by weather data and observation data, water of supply and drainage were estimated as the result of SWMM model analysis. The applicability of the SWMM model was verified using RMSE and R-square values. The result of analysis from 2017 to 2020, the average annual quick return flow rate was 53.1%. Based on these results, the analysis of water circulation characteristics can perform, it can be provided as basic data for integrated water management.

• Journal of Korea Water Resources Association
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• v.55 no.8
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• pp.623-634
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• 2022

Due to river maintenance projects such as the creation of hydrophilic areas around rivers and the Four Rivers Project, the flow characteristics of rivers are continuously changing, and the risk of water quality accidents due to the inflow of various pollutants is increasing. In the event of a water quality accident, it is necessary to minimize the effect on the downstream side by predicting the concentration and arrival time of pollutants in consideration of the flow characteristics of the river. In order to track the behavior of these pollutants, it is necessary to calculate the diffusion coefficient and dispersion coefficient for each section of the river. Among them, the dispersion coefficient is used to analyze the diffusion range of soluble pollutants. Existing experimental research cases for tracking the behavior of pollutants require a lot of manpower and cost, and it is difficult to obtain spatially high-resolution data due to limited equipment operation. Recently, research on tracking contaminants using RGB drones has been conducted, but RGB images also have a limitation in that spectral information is limitedly collected. In this study, to supplement the limitations of existing studies, a hyperspectral sensor was mounted on a remote sensing platform using a drone to collect temporally and spatially higher-resolution data than conventional contact measurement. Using the collected spatio-temporal hyperspectral images, the tracer concentration was calculated and the transverse dispersion coefficient was derived. It is expected that by overcoming the limitations of the drone platform through future research and upgrading the dispersion coefficient calculation technology, it will be possible to detect various pollutants leaking into the water system, and to detect changes in various water quality items and river factors.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.257-265
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• 2023

The purpose of this study was to vaccinate every year according to the general characteristics of COVID-19, whether to vaccinate every year according to the vaccination experience, whether to vaccinate every year according to knowledge/attitude about vaccination, and negative responses to the vaccinate every year In order to understand the factors affecting the vaccination physician every year by identifying the factors of Statistical analysis is based on general characteristics, variables based on vaccination experience, and knowledge/attitudes related to vaccination. The doctor calculates the frequency and percentage, A square test (-test) was performed, and if the chi-square test was significant but the expected frequency was less than 5 for 25% or more, a ratio difference test was performed with Fisher's exact test. Through multiple logistic regression analysis using variables that were significant in simple analysis, a predictive model for future vaccination and the effect size of each independent variable were estimated. As statistical analysis software, SAS 9.4 (SAS Institute Inc., Cary, NC, USA) was used, and because the sample size was not large, the significance level was set at 10%, and when the p-value was less than 0.10, it was interpreted as statistically significant. In the simple logistic regression analysis, the reason why they answered that they would not be vaccinated every year was that they answered 'to prevent infection of family and hospital guests' rather than 'to prevent my infection' as the reason for the vaccination. It was 11.0 times higher and 3.67 times higher in the case of 'for the formation of collective immunity of the local community and the country'. The adverse reactions experienced after the 1st and 2nd vaccination were 8.42 times higher in those who did not experience pain at the injection site than those who did not, 4.00 times higher in those who experienced swelling or redness, and 5.69 times higher in those who experienced joint pain. There was a 5.57 times higher rate of absenteeism annually than those who did not. In addition, the more anxious they felt about vaccination, the more likely they were to not get the vaccine every year by 2.94 times.

• Journal of the Korean Orthopaedic Association
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• v.54 no.4
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• pp.336-342
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• 2019

Purpose: To examine the relationship between the progression of a kyphotic deformity and the magnetic resonance imaging (MRI) findings in conservatively treated osteoporotic thoracolumbar compression fracture patients. Materials and Methods: This study categorized the patients who underwent conservative treatment among those patients who underwent treatment under the suspicion of a thoracolumbar compression fracture from January 2007 to March 2016. Among them, this retrospective study included eighty-nine patients with osteoporosis and osteopenia with a bone density of less than -2.0 and single vertebral body fracture. This study examined the MRI of anterior longitudinal ligament or posterior longitudinal ligament injury, superior or inferior endplate disruption, superior of inferior intravertebral disc injury, the presence of low signal intensity on T2-weighted images, and bone edema of intravertebral bodies in fractured intravertebral bodies. Results: In cases where the superior endplate was disrupted or the level of bone edema of the intravertebral bodies was high, the kyphotic angle, wedge angle, and anterior vertebral compression showed remarkably progression. In the case of damage to the anterior longitudinal ligament or the superior disc, only the kyphotic angle was markedly prominent. On the T2-weighted images, low signal intensity lesions showed a high wedge angle and high anterior vertebral compression. On the other hand, there were no significant correlations among the posterior longitudinal ligament injury, inferior endplate disruption, inferior disc injury, and the progression of kyphotic deformity and vertebral compression. The risk factors that increase the kyphotic angle by more than 5° include the presence of injuries to the anterior longitudinal ligament, superior endplate disruption, and superior disc injury, and the risk factors were 21.3, 5.1, and 8.5 times higher than those of the uninjured case, and the risk differed according to the level of bone edema. Conclusion: An osteoporotic thoracolumbar compression fracture in osteoporotic or osteopenic patients, anterior longitudinal ligament injury, superior endplate and intravertebral disc injury, and high level of edema in the MRI were critical factors that increases the risk of kyphotic deformity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.595-601
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• 2008

The purpose of this study is to investigate the trends and patterns of various kind of water uses in a household by metering in Korea. Water use components are classified by toilet, washbowl, bathing, laundry, kitchen, miscellaneous. Flow meters are installed in 140 household selected by sampling in all around Korea. The data are gathered by web-based data collection system from the year 2002 to 2006, considering pre-investigated data such as occupation, revenue, family members, housing types, age, floor area, water saving devices, education, miscellaneous. Reliable data are selected by upper fence method for each observed water use component and statistical characteristics are estimated for each residential type to determine liter per capita per day. Estimated domestic per capita day show an indoor water use with the range from 150 lpcd to 169 lpcd for each housing type as the order of high rise apartment, multi-house, and single house. As the order of consuming amount among water use components, it is investigated that toilet (38.5 lpcd) is the first, and the second is laundry water (30.8 lpcd), the third is kitchen (28.4 lpcd), the fourth is bathtub (24.7 lpcd), the next is washbowl (15.4 lpcd). The results are compared with water uses in U.K. and U.S. As life style has been changed into western style, pattern of water use in Korea is tend to be similar with the U.S. water use pattern. Compared with the surveying results by Bradley, on 1985. Thirty liter of total use increased with the advancement of economic level, and a little change of water use pattern can be found. Especially, toilet water take almost half part of total water use and laundry water shows lowest as 11% in surveying at the year of 1985. But, this study shows that 39 liter, 28% of toilet water, has been decreased by the spread of saving devices and campaign. It is supposed that the spread large sized laundry machine make by-hand laundry has been decreased and water use increased. Unit water amount of each end-use in household can be applied to design factor for water and wastewater facilities, and it play a role as information in establishing water demand forecasting and conservation policy.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.353-365
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• 2023

The effects of climate change on green infrastructure and environmental media remain uncertain and context-specific despite numerous climate projections globally. In this study, the extreme weather conditions in seven major cities in South Korea were characterized through statistical analysis of 20-year daily meteorological data extracted fro m the Korea Meteorological Administration (KMA). Additionally, the impacts of extreme weather on Nature-based Solutions (NbS) were determined through a comprehensive review. The results of the statistical analysis and comprehensive review revealed the studied cities are potentially vulnerable to varying extreme weather conditions, depending on geographic location, surface imperviousness, and local weather patterns. Temperature extremes were seen as potential threats to the resilience of NbS in Seoul, as both the highest maximum and lowest minimum temperatures were observed in the mentioned city. Moreover, extreme values for precipitation and maximum wind speed were observed in cities from the southern part of South Korea, particularly Busan, Ulsan, and Jeju. It was also found that extremely low temperatures induce the most impact on the resilience of NbS and environmental media. Extremely cold conditions were identified to reduce the pollutant removal efficiency of biochar, sand, gravel, and woodchip, as well as the nutrient uptake capabilities of constructed wetlands (CWs). In response to the negative impacts of extreme weather on the effectiveness of NbS, several adaptation strategies, such as the addition of shading and insulation systems, were also identified in this study. The results of this study are seen as beneficial to improving the resilience of NbS in South Korea and other locations with similar climate characteristics.

• Tuberculosis and Respiratory Diseases
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• v.43 no.4
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• pp.600-612
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• 1996

Background : Recent studies deported that untreated patients with obstructive sleep apnea syndrome had high long-term mortality rates, and cardiovascular complications of these patients clad a major effect on mortality. Several data indicates that obstructive sheep apnea syndrome contributes to the development of diurnal systemic hypertension. But the pathophysiological mechanism of the development of systemic hypertension in these patients is still uncertain. This study was performed to evaluate the possible role of sympathetic nervous system activity for the development of systemic hypertension in patients with obstructive sleep apnea syndrome. Method : 35 patients with obstructive sleep apnea syndrome(OSAS) and 13 Control subjects(control) were included in this study. 21 patients of OSAS were normotensives(OSAS-NBP), and 14 patients of OSAS were hypertensives(OSAS-HBP). Full night polysomnography was undertaken to all subjects. We measured plasma norepinephrine(NE) and epinephrine(EP) concentrations during waking and sleep, using high performance liquid chromatography, in all patients and control subjects. Results : In OSAS, OSAS-NBP and control, plasma NE and EP concentrations during sleep were lowed than during waking(p<0.01). But, in OSAS-HBP, these was no difference between during waking and sleep. Plasma NE concentrations during sleep of OSAS, OSAS-NBP and OSAS-HBP were higher than Control(p<0.05). In OSAS-HBP, daytime systolic blood pressure correlated with plasma NE concentration during sleep(r=0.7415, p<0.01), arid correlated inversely with mean arterial oxygen saturation(r=-0.6465, p<0.05) or arterial oxygen saturation nadir(r=-0.6) 14, p<0.05) during sleep. Conclusion : The sympathetic activity during sleep of obstructive sleep apnea syndrome patients was higher than control subjects. In obstructive sleep apnea syndrome patients with systemic hypertension, there was no diurnal variation of sympathetic activity, and there was correlation between daytime systolic blood pressure and sympathetic activity during sleep. These data suggests that chronic hyperactivity of sympathetic nervous system may contribute to the development of diurnal systemic hypertension in patients with obstructive sleep apnea syndrome.

• Journal of Gastric Cancer
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• v.6 no.3
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• pp.154-160
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• 2006

Purpose: According to the 2nd English Edition of the Japanese Gastric Cancer Association (JGCA) in 1998, in case of distal gastric cancer, the 14v (superior mesenteric vein) lymph node (LN) is included in the N2 group. However, in Korea, a modified radical gastrectomy is performed, and a 14v LN dissection is not done as a routine procedure. Thus, we investigated the rate of metastatic 14v LNs, evaluated the necessity of dissection of the 14v LN, and searched for indications of 14v LN dissection. Materials and Methods: From April 2004 to August 2005, we enrolled the patients who were diagnosed as having advanced gastric cancer in the distal third portion of the stomach. We peformed a distal gastrectomy with D2 lymph node dissection as defined in the 2nd English edition of the JGCA classification. We calculated the positive rate of metastatic LNs of each station and analyzed the relationship between the positive rates of No.6 LNs and 14v LNs. We also compared the positive 14v LN group with the negative 14v LN group. Results: The total number of patients was 50, the mean age was 56 (range $30{\sim}80$) years, and sex ratio (Male/Female) was 1.63 : 1. In 47 (94%) cases, distal a gastrectomy with gastroduodenostomy was done, and in the remaining 3 (6%) cases, a distal gastrectomy with gastrojejunostomy was done. The most frequently metastatic LNs were nos. 3 and 6 (54%). The metastatic rate of the f4v LN was 10%, which was similar to that of LN no. 9. In the comparison of the 14v positive group with the 14v negative group, there were significant differences in the numbers of metastatic LNs (mean 25.4 vs 4.91, P<0.001) and the numbers of metastatic no. 6 LNs, (mean 6.8 vs 1.42, P<0.001), and if no. 6 LNs were metastatic, the possibility of metastasis to the 14v LN was 19.2%. In the 14v positive group, all cases were more than stage 3 by the UICC 6th edition. Conclusion: In cases of advanced cancer with metastasis to the no. 6 IN, there was a good chance of metastasis to the 14v LN. Thus, in the operative field, if the tumor is advanced to more than stage 3 by the UICC classification and the no. 6 LN is metastatic, a 14v LN dissection is necessary. However, the usefulness of a 14v LN dissection should be evaluated prospectively through an analysis of tumor recurrence and long-term survival.

• Tuberculosis and Respiratory Diseases
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• v.48 no.4
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• pp.448-463
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• 2000

Background : Pulmonary infiltrate is a frequent cause of morbidity and mortality in patients with leukemia. It is often hard to obtain a reliable diagnosis by clinical and radiologic findings alone. The aim of this study was to evaluate diagnostic and therapeutic benefits of invasive procedures for new lung infiltrates in leukemia. Methods : Patients with leukemia who developed new lung infiltrates from December 1994 to March 1999 were included in this study. These patients were classified into the empirical group who received empirical therapy only and into the invasive group who underwent bronchoscopy or surgical lung biopsy for the diagnostic purpose of new lung infiltrates. A retrospective chart review was done to find the etiologies of new lung infiltrates, the yield of invasive procedures, outcome as well as predicting factors for survival. Results : 1) One hundred-two episodes of new lung infiltrates developed in 90 patients with leukemia. Invasive procedures were performed in 44 episodes while 58 episodes were treated with empirical therapy only. 2) Invasive procedures yielded a specific diagnosis in 72.7%(32/44), of which 78.1% had infectious etiology. Therapeutic plan was changed in 52.3%(23/44) of patients after invasive procedures. None of them showed procedure-related mortality. 3) The overall survival rate was 62.7%(64/102). Survival rate in the invasive group (79.5%) was significantly better than that in the empirical group (50.0%) (p=0.002). 4) Upon multivariate analysis, the performance of invasive procedures, no need for mechanical ventilation and achievement of complete remission of leukemia after induction chemotherapy were the independent predicting factors for survival in patients with leukemia and new lung infiltrates. Conclusion : Bronchoscopy and surgical lung biopsy are useful in the diagnosis of new lung infiltrates in patients with leukemia. However, survival benefits of invasive procedures should be considered together with disease status of leukemia and severity of respiratory compromise.

• Journal of Chest Surgery
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• v.38 no.1 s.246
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• pp.44-49
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• 2005

Although thymomas are relatively common mediastinal tumors, to date not only has a universal system of pathologic classification not been established but neither has a clearly defined predictable relationship between treatment and prognosis been made. Recently, a new guideline for classification was reported by WHO, and efforts, based on this work, have been made to better define the relationship between treatment and pro­gnostic outcome. In the present study a comparative analysis between the WHO classification and Masaoka stage system with the clinical disease pattern was conducted. Material and Method: A total of 98 patients undergoing complete resection for mediastinal thymoma between Juanuary 1993 and June 2003 were included in the present study. The male female ratio was 48 : 50 and the mean age at operation was $49.6{\pm}13.9\;years.$ A retrospective analytic comparison studying the relationship between the WHO classification and the Masaoka stage system with the clinical disease pattern of thymoma was conducted. Pathologic slide specimens were carefully examined, details of postoperative treatment were documented, and a relationship with the prognostic outcome and recurrence was studied. Result: There were 7 patients in type A according to the WHO system of classification, 14 in AB, 28 in B 1, 23 in B2, 18 in B3, and 9 in type C. The study of the relationship between the Masaoka stage and WHO classification system showed 4 patients to be in WHO system type A, 7 in type AB, 22 in B 1, 17 in B2, and 3 in type B3 among 53 $(54{\%})$ patients shown to be in Masaoka stage I. Among 28 $(28.5{\%})$ patients in Masaoka stage II system, there were 2 patients in type A, 7 in AB, 4 in B 1, 2 in B2, 8 in B3, and 5 in type C. Among 15 $(15.3{\%})$ in Masaoka stage III, there were 1 patient in type B1, 3 in B2, 7 in B3, and 4 in type C. Finally, among 2 $(2{\%})$ patients found to be in Masaoka stage IV there was 1 patient in type B1, and 1 in type B2. The mean follow up duration was $28{\pm}6.8$ months. There were 3 deaths in the entire series of which 2 were in type B2 (Masaoka stages III and IV), and 1 was in type C (Masaoka stage II). Of the patients that experienced relapse, 6 patients remain alive of which 2 were in type B2 (Masaoka III), 2 in type B3 (Masaoka I and III) and 2 in type C (Masaoka stage II). The 5 year survival rate by the Kaplan-Meier method was $90{\%}$ for those in type B2 WHO classification system, $87.5{\%}$ for type C. The 5 year freedom from recurrence rate was $80.7{\%}$ for those in WHO type B2, $81.6{\%}$ for those in type B3, and $50{\%}$ for those in type C. By the Log-Rank method, a statistically significant correlation between survival and recurrence was found with the WHO system of classification (p<0.05). An analysis of the relationship between the WHO classification and Masaoka stage system using the Spearman correction method, showed a slope=0.401 (p=0.023), showing a close correlation. Conclusion: As type C of the WHO classification system is associated with a high postoperative mortality and recurrence rate, aggressive treatment postoperatively and meticulous follow up are warranted. The WHO classification and Masaoka stage system were found to have a close relationship with each other and either the WHO classification method or the Masaoka stage system may be used as a predict prognostic outcome of Thymoma.