• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.601-610
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• 2023

The comprehension of water-level behavior in rivers is essential for effective flood and river environmental management. The objective of this study is to propose a methodology that can be used by field engineers engaged in actual practice, to readily identify the characteristics of water-level behavior during flood events. To this end, a total of 45 historical water-level records from 2010 to 2022 year, which provide flood information for the flood vulnerable districts of the Han River, were obtained. A Water-level Rise Behavior Curve (WRBC) was developed and suggested to quantify the amount of water-level rise per unit time during flood. As a result, the water-level rises by more than 80% of the total rise within the first 6.2 hours, followed by a gradual rise. The time required to achieve a particular equilibrium varied depending on the area and runoff characteristics of the upstream. Furthermore, the study revealed that the WRBC provides a statistical representation of the water-level rise trend during floods, and can be effectively utilized for flood mitigation measures in waterfront spaces and irrigation facilities.

• Journal of agricultural medicine and community health
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• v.25 no.1
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• pp.51-63
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• 2000

Ten Dongs were selected according to the systematic cluster sampling in Koryong Gun, and the survey was conducted on 571 women in the age between 30-69 years. The first survey was performed for 6 days between August 27 to September 1, 1999 with the investigation rate of 60.3%, and the second survey was performed in November with the investigation rate of 91.8%. The contents of survey included demographic characteristics, health behaviors, dyspepsia symptom score, sleeping induction time and the degree of sleep satisfaction, and degree of stress in the subjects. The dyspepsia symptom score was in the average 13.4 points out of a total 44 points and was the highest in the 50-59 year-old age group with 13.9 points. The sleep induction time was in the average of 35 minutes and was the highest in the 50-59 year-old age group with 40.9 minutes; the degree of sleep satisfaction was in the average of 7.9 points and was the lowest in the 50-59 year-old age group with 7.5 points. The stress score was in the average of 18.3 points and was highest in those subjects in their 40's and 50's with 18.7 points. When the correlation among the stress score, the degree of sleep satisfaction and dyspepsia symptom score was analyzed, the results showed that he stress score and the degree of sleep satisfaction showed a significant negative correlation and that the stress score and dyspepsia symptom score showed a significant positive correlation. Also, a significant negative correlation was found between the degree of sleep satisfaction and dyspepsia symptom score. According to each age group, a significant correlation was revealed among the stress score, dyspepsia symptom score and the degree of sleep satisfaction in those subjects over 40 years of age compared to those subjects who were younger than 40 years of age. As for educational level, the correlation among the stress score, the degree of sleep satisfaction and dyspepsia symptom score was higher in those subjects with less than middle school education compared to those subjects with more than high school education. When those factors that effects on the dyspepsia symptom score were analyzed with multiple regression, the results showed that the level of stress and chronic diseases were selected as significant variables. When those factors that affected on the degree of sleep satisfaction were analyzed, the sleep induction time and presence of chronic diseases and stress were selected as significant variables. Those women in their 50's who live in rural areas showed the highest level of stress, lowest the degree of sleep satisfaction, and highest level of dyspepsia, indicating that they need stress management. Also, since stress was showed to be a significant variable effecting on dyspepsia or the degree of sleep satisfaction, it is concluded that health promotion is possible through stress management. More studies are needed in the future on coping resources that would strengthen coping against stress, and by conducting studies on stress and related factors on community people, the measures of mental health promotion need to be developed.

• The Korean Journal of Applied Statistics
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• v.28 no.4
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• pp.721-739
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• 2015

The importance of the old age income security will increase for an aging society due to the deepening income polarization. The National Pension(NP) is a representative Social Security scheme in charge of old age income security as well as income redistribution for the insured. Studies by Kim (2002), Kim et al. (2003), and Hong (2013) have reported the possibility of unsatisfactory income redistribution of the NP. Recently Choi (2015) attributed those results to an unnoticed defect in the benefit formula. This study is a test for the unsatisfactory income redistribution of the current National Pension using early participants who have now become pensioners. The method aggregates cohorts and combines individual history data before the year 2013 and the results of the actuarial projection model of the 2013 after the year 2014. The results are divided by measures taken. The redistribution is obviously progressive by the income replacement rate; however, it is significantly regressive when measured by the net benefit theoretically as more plausible. Considering the effect of differing lifetime contribution year among income classes, the regressive redistribution will prevail more in the future pensioners.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.519-525
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• 2010

Data from beam-based bond tests for FRP bars in the literature were collected and regression analyses were conducted for the data of splitting failure. Average bond strengths obtained from splice tests were found to be lower and more affected by C/$d_b$ values than average bond strengths from anchorage tests, indicating needs of new design equation for the splice length of FRP bars based on the data of splice tests only. In addition, the variation of bond strengths was greater than that of tensile strengths of FRP bars and, therefore, a new safety factor should be involved for the design equation. Five percent fractile coefficients were used to develop the design equations based on the assumption that load and resistance factors for FRP reinforced concrete structures are same to the factors for steel reinforced concrete structures. The proposed design equations give economical and reliable lengths for development and splice of FRP bars. The proposed equation for splice provides shorter lengths than the ACI 440 equation in case of C/$d_b$ of 3.0 or greater. Because FRP bars are expected to be used in slabs and walls exposed to weather with thick cover and large spacing between bars, the proposed equation gives optimal splice lengths.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.4
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• pp.7-15
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• 2000

The purpose of this work is to evaluate the solderahility and characteristics of solder joints. Bridge defect of solder joint was examined in natural atmosphere and $N_2$ condition. Consequently, wettability was excellent for each of Sn-Pb plated Cu specimen, Sn plated Cu specimen, and Cu polished in $N_2$ condition. The wetting time in $N_2$ condition was shorter than that of natural atmosphere condition, showing the decreasing values of about 0.2~0.45 seconds. The max. wetting force under the $N_2$ condition was more increasing that of natural atmosphere condition, showing the increasing values of about 1.8~2.8 N. With the result of wetting balance test, the wetting time ($t_2$) and wetting farce according to increasing amount of $N_2$ from 10 1/min to 30 1/min, the wetting time ($t_2$) was reduced about 0.25 second and wetting force was increased about 2.3 N. In non-cleaning flux, when $N_2$ gas is applied, it is compensated to decrease of wettability. In the case of using the $N_2$ gas, the wettability was improved. The reason for improving wettability is due to preventing the formation of dross. The generation rate of bridge in $N_2$ condition decreased than that of natural atmosphere, and when the specimen had a fine pitch, the rate of bridge defects was considerably decreased in $N_2$ condition, showing the decreasing rate of 25~75%.

• Journal of Korea Water Resources Association
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• v.37 no.9
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• pp.695-706
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• 2004

This study is to propose the temporal pattern of design rainfall which causes maximum peak discharge, and to analyze the relation of catchment characteristics and critical durations for gauged midsize catchment. Hydrologic analysis has done over the 44 midsize catchments with 50-5,000$\textrm{km}^2$. The type of temporal pattern of design rainfall which causes maximum peak discharge has resulted in Huff's 4 quartile distribution method for effective rainfall(AMC III) The peak discharges of 24hr rainfall duration are similar to those of critical duration for 50-600$\textrm{km}^2$, and the peak discharges of 48hr rainfall duration are similar to those of critical duration for 600-5,000$\textrm{km}^2$. Therefore, if the proper rainfall intensity formula is selected, 24hr or 48hr rainfall duration may be regarded as the critical duration of midsize catchment. A simple regression equation is derived by using a catchment area and critical duration with high correlation for the case of effective rainfall(AMC III). Therefore, it can be used to determine the critical duration of ungauged catchment with 50-5,000$\textrm{km}^2$. Also, dimensionless regression equation is derived by using characteristic values of unit hydrograph.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.7134-7147
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• 2014

This study examined one of the contemporary issues that may be interesting to academics and practitioners regarding the driving force of the growth rate for the firms belonging to the chaebols in the Korean capital markets. With respect to the empirical results obtained from two hypothesis tests, the first hypothesis was to identify any financial determinants on the growth rate by applying both dynamic panel data and static panel data models. The debt ratios relevant to the book- and market-value showed their positive relationships with the DV of GROWTH1, along with other significant IDVs such as one-period lagged DV of GROWTH_1, SIZE1 and FOS with statistical significance. Second, by employing conditional quantile regression (CQR) analysis, the control variables, such as ROA, SMARKET, time dummy variable of F2010 and F2011, and the industry dummies of IND3 and IND10, provided evidence of their significant influences on DV of GROWTH1.

• Water for future
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• v.26 no.1
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• pp.115-124
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• 1993

This study is to determine the critical duration of design rainfall and to utilize it for the design of detention pond with pump station. To examine the effect of the duration and temporal distribution of the design rainfall, Huff's quartile method is used for the 9 cases of durations ranging from 20 to 240 minutes with 10 years return period, and the ILLUDAS model is used for runoff analysis. The storage ration which is the ratio of maximum storage amounts to total runoff volume, is introduced to determine the critical duration of design rainfall. The duration which maximizes the storage ratio is adopted as the critical duration. This study is applied to 18 urban drainage watersheds with pump station in Seoul, of which the range of watershed area is $0.24-12.70\textrm{km}^2.$ The result of simulation shows that the duration which maximizes storage ration is 30 and 60 minutes on the whole. It is shown also that the storage ration of 2nd- and 3rd-quartile pattern is larger than that of 1st- and 4th-quartile pattern of temporal distribution. A simplified empirical formula for Seoul area is suggested by using the regression analysis between the maximum storage ration and the peak ratio, and can be utilized for the preliminary design and planning of detention pond with pump station.

• Journal of Korea Water Resources Association
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• v.42 no.10
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• pp.773-783
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• 2009

The effects of rainfall input uncertainty on predictions of stream flow are studied based extended GLUE (Generalized Likelihood Uncertainty Estimation) approach. The uncertainty in the rainfall data is implemented by systematic/non-systematic rainfall measurement analysis in Weida catchment, Germany. PDM (Probability Distribution Model) rainfall runoff model is selected for hydrological representation of the catchment. Using general correction procedure and DUE(Data Uncertainty Engine), feasible rainfall time series are generated. These series are applied to PDM in MC(Monte Carlo) and GLUE method; Posterior distributions of the model parameters are examined and behavioural model parameters are selected for simplified GLUE prediction of stream flow. All predictions are combined to develop ensemble prediction and 90 percentile of ensemble prediction, which are used to show the effects of uncertainty sources of input data and model parameters. The results show acceptable performances in all flow regime, except underestimation of the peak flows. These results are not definite proof of the effects of rainfall uncertainty on parameter estimation; however, extended GLUE approach in this study is a potential method which can include major uncertainty in the rainfall-runoff modelling.

• Food Science of Animal Resources
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• v.23 no.1
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• pp.32-38
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• 2003

The effects of curing temperatures(1, 5 and 10$^{\circ}C$) and times on the chemical properties and palatability of cured pork loins which were cured in the 7% curing solution were investigated. The pork loins cured at 10$^{\circ}C$ curing temperature showed the decreased level of pH and water holding capacity up to 15 days of curing time. The growth of bacteria in the curing solution and surface region of cured loins, cured at 10$^{\circ}C$ were rapid after 12 days of curing. However, bacteria were not detected(<0.05${\times}$10$^2$ CFU/g) in the central region of cured loin until 15 days of curing. The penetration of salt into the central region of cured loins was faster at 10$^{\circ}C$ curing temperature than at lower curing temperatures for all curing times. The difference of salt contents between surface and central regions in the cured loins was less at higher temperature than at lower temperatures, and the difference decreased in boiling process for all curing times. The color fixation of the cured boiled loins was better at 5 and 10$^{\circ}C$ curing temperatures than at 1$^{\circ}C$. The sensory scores for saltiness and flavor of the cured boiled pork loins were higher at higher temperature than at lower temperatures until 9∼12 days of curing. Palatable cured boiled pork loins could be produced under the curing solution at low temperatures of 1 and 5$^{\circ}C$ for 12 and 9 days, respectively.