• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.421-433
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• 2014

In this study, monthly and annual aridity indices which are the ratios of precipitation to potential evapotranspiration in Seoul climate measurement station were analyzed for past 50 years (1961~2010), and the ratio of aridity index simulated by climate change scenarios (RCP 4.5 and 8.5) for each future period (2011~2040, 2041~2070, 2071~2100) to aridity index for the past period (1971~2000) was analyzed. Furthermore, 5 different potential evapotranspiration equations (FAO P-M, Penman, Makkink, Priestley-Taylor, Hargreaves) were applied to analyze the effect of potential evapotranspiration equation on estimating aridity index and aridity index variation ratio (%). The study results indicate that the monthly precipitation, average temperature and potential evapotranspiration were increased in each future period as compared to past period for both RCP 4.5 and RCP 8.5. Furthermore, winter period showed more significant increase of potential evapotranspiration than summer period, but aridity index showed different patterns as compared with potential evapotranspiration reflecting the influence of precipitation. Therefore, it is necessary to make preparation for the increment of winter evapotranspiration in terms of water resources management. The monthly and annual aridity indices based on future climate change scenarios were greatly different according to potential evapotranspiration equations; however, monthly and annual patterns of aridity index variation ratio (%) in the future period as compared to past period were very similar regardless of applied potential evapotranspiration equation.

• 한국해양학회지
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• v.29 no.2
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• pp.107-118
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• 1994

An investigation of the annual change and C:N:P ratio in particulate organic matter (POM) in Chinhae Bay, a semi-enclosed bay of the southern coast of Korean Peninsula, was carried out for a period of 12 months between January and December, 1993. The concentrations of POM have a broad range: 198∼4,416 ugC/l, 24∼792 ugN/l and 4.5∼69.0 ugP/l, Marked seasonal changes of POM, particularly particulate organic carbon (POC) and nitrogen (PON), were observed in the surface water. Generally, the concentration of POM peaks in summer. The C:N:P composition ratio of particulate organic matter, which is high in summer, also shows a seasonal change. The C:N assimilation ratio is constant at 6.53, which is consistent with the Redfield ratio. The significant linear relationship between POM and chlorophyll-a in the surface water during the survey period (except for January and February) and the C:N ratio suggest that the concentration of POM is controlled by phytoplankton biomass. POM peaks in summer, a period characterized by high freshwater input and the strong stratification, as a result of the intense proliferation of phytoplankton by a large amount of nutrient loading from the tributaries. On the other hand, the high C:P and N:P ratios in summer indicate that P is limited for phytoplankton growth owing to N-enrichment from a high input of freshwater with a high dissolved inorganic N:P ratio.

• Journal of Gastric Cancer
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• v.1 no.3
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• pp.161-167
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• 2001

Purpose: Although gastric carcinomas occur throughout the world and the incidence is on the decrease, they remain the most common type of carcinoma in Korea. Significant advancements in the diagnostics and the surgical treatment of gastric carcinomas have been achieved during the last three decades. The present retrospective study was undertaken to investigate the chronological changes in the clinical features, including clinicopathological findings, operative treatment, and prognosis of gastric carcinomas. Materials and Methods: A total of 1973 patients with a primary gastric adenocarcinoma who had been treated surgically during the period from 1983 to 1998 at the Department of Surgery, Korea University College of Medicine, were divided into two groups to evaluate chronological changes: 1007 patients had been treated during the period from 1983 to 1992 (early period) and 966 patients during the period from 1993 to 1998 (late period). Chronological changes in age, sex, ratio of early gastric cancer (EGC), and resectability were analyzed in all 1973 cases. For the 1755 resected cases, we also studied the chronological changes in the clinicopathological and treatment factors between the early-period (n=894) and the late-period (n=867) groups. Results: There were significant differences between the two periods with regard to age and ratio of EGC: EGC was more frequent in the late period. Univariate analysis of resected cases showed that gross type, tumor size, depth of invasion, UICC stage, and histological type were statistically significant. The analysis of the treatment factors revealed that total gastrectomies and extended lymphadenectomies were more frequent during the late period. The number of lymph nodes dissected was $26.0\pm12.7$ in the early period and $33.4\pm14.1$ in the late period (p<0.01). The 5-year survival rate in all cases was $51.4\%$ in the early period and $55.9\%$ in the late period. The stage-related survival rates (UICC 4th Ed., 1987) in the early vs. the late periods were $92.9\%\;vs.\;95.5\%$ in stage IA, $82.1\%\;vs.\;91.1\%$ in stage IB, $76.5\%\;vs.\;73.1\%$ in stage II, $46.5\%\;vs.\;52.1\%$ in stage IIIA, $14.5\%\;vs.\;33.6\%$ in stage IIIB, and $2.8\%\;vs.\;8.8\%$ in stage IV. There was a statistically significant difference in survival between stage IIIB and IV. Conclusion: These results suggest that the differences in the clinicopathological findings are related primarily to the increased number of early gastric cancer cases in the late period and that the improved survival noted during the late period for in stage IIIB and IV cancers might be related to extended surgery.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.4
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• pp.359-362
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• 1996

A study was conducted to assess the influence of copper on the total sulphur amino acid requirements of broiler chickens reared under two growing periods. The TSAA levels used were 0.73, 0.83, 0.93% with copper levels of 0, 125, 250 and 375 mg/kg for the starter period and the TSAA levels of 0.72, 0.79 and 0.86% with copper levels of 0, 125, 250 and 375 mg/kg for the grower period. Total feed consumption, body weight gain and feed L gain ratio were used as the parameters for the assessment. The results showed that adding copper at 250 mg/kg to the diets improved feed : gain ratio of the starter broilers and resulted in small improvement of body weight gain and feed : gain ratio of the grower broilers. Growth was depressed in relation to the reduction of feed intake on the chicks fed diet containing 375 mg/kg copper. There was a significant interaction between dietary TSAA and copper levels for feed intake, hence, indicating that the supplementation of copper at the level of 375 mg/kg increased the TSAA requirement of the starter broilers, although no interference with the requirement of grower broilers.

• Journal of Environmental Science International
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• v.29 no.1
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• pp.33-44
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• 2020

Recently, a variety of modeling studies have been conducted to examine the air quality over South Korea during the Korea - United States Air Quality (KORUS-AQ) campaign period (May 1 to June 10, 2016). This study investigates the impact of different meteorological initializations on atmospheric modeling results. We conduct several simulations during the KORUS-AQ period using the Weather Research and Forecasting (WRF) model with two different initial datasets, which is FNL of NCEP and ERA5 of ECMWF. Comparing the raw initial data, ERA5 showed better accuracy in the temperature, wind speed, and mixing ratio fields than those of NCEP-FNL. On the other hand, the results of WRF simulations with ERA5 showed better accuracy in the simulated temperature and mixing ratio than those with FNL, except for wind speed. Comparing the nudging efficiency of temperature and wind speed fields, the grid nudging effect on the FNL simulation was larger than that on the ERA5 simulation, but the results of mixing ratio field was the opposite. Overall, WRF simulation with ERA5 data showed a better performance for temperature and mixing ratio simulations than that with FNL data. For wind speed simulation, however, WRF simulation with FNL data indicated more accurate results compared to that with ERA5 data.

• Earthquakes and Structures
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• v.19 no.5
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• pp.379-393
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• 2020

The purpose of this study is to first evaluate the seismic behavior of ageing arch bridges by using the Intensity Measure - based demand and DCFD format, which is referred to as the fragility-hazard format. Then, an investigation is performed for their seismic vulnerability. Analytical models are created for bridges concerning different features and these models are subjected to Incremental Dynamic Analysis (IDA) analysis using a set of 22 earthquake records. The hazard curve and results of IDA analysis are employed to evaluate the return period of exceeding the limit states in the IM-based probabilistic performance-based context. Subsequently, the fragility-hazard format is used to assess factored demand, factored capacity, and the ratio of the factored demand to the factored capacity of the models with respect to different performance objectives. Finally, the vulnerability curves are obtained for the investigated bridges in terms of the loss ratio. The results revealed that decreasing the span length of the unreinforced arch bridges leads to the increase in the return period of exceeding various limit states and factored capacity and decrease in the displacement demand, the probability of failure, the factored demand, as well as the factored demand to factored capacity ratios, loss ratio, and seismic vulnerability. Finally, it is derived that the probability of the need for rehabilitation increases by an increase in the span length of the models.

• Journal of Environmental Science International
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• v.23 no.10
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• pp.1731-1743
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• 2014

The time variations in relative humidity observed at the Gangjeong (Goryeong) Reservoir in the Nakdong River over a one-year period (September 2012-August 2013) were analyzed with the Bowen ratio. The thermal vertical scale of the reservoir was also evaluated following Yamamoto's method. The study's results showed that the relative humidity at the reservoir was higher than that of the Daegu Meteorological Observatory (inland) all year round. The difference was slightly larger at nighttime (17-20 %) than at daytime (13-15 %) in all seasons except summer. The quantitative order of latent heat flux was summer, spring, autumn, and winter. This finding signifies that the thermal vertical scale of the reservoir corresponds to that of a shallow lake. The Bowen ratio was smallest at midday of the summer season. In other words, the net radiation energy was converted more as latent heat flux than sensible heat flux during a higher temperature period.

• Korea Journal of Hospital Management
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• v.24 no.2
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• pp.1-11
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• 2019

Purpose: The purpose of this study is to identify relationship between work unstability and personal medical expenditure ratio focusing on wage workers' contract period. Method: This study analyzed 2015 yearly data beta version of Korea Health Panel, co-managed by Korea Institute for Health and Social Affairs and National Insurance Corporation for data analysis. When executing linear regression, Household income was applied with equivalized income, and the proportion of personal medical expenditure was naturally logged to perform linear regression and the demographic and socioeconomic factors were taken into account. The demographic and socio-economic factors were also considered. Findings: As a result of reviewing the used factors, it was found that the more unstable work status, the higher personal medical expenditure ratio. This result corresponds to 'The Theory of Fundamental Causes' by Link & Phelan. Conclusion : It indicates that policy efforts should be made to improve the working environment and health level of socially unstable workers.

• Earthquakes and Structures
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• v.22 no.6
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• pp.571-584
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• 2022

The residual displacement ratio (RDRs) response spectra have been generally used as an important means to evaluate the post-earthquake repairability, and the ratios of residual to maximum inelastic displacement are considered to be more appropriate for development of the spectra. This methodology, however, assumes that the expected residual displacement can be computed as the product of the RDRs and maximum inelastic displacement, without considering the correlation between these two variables, which inevitably introduces potential systematic error. For providing an adequately accurate estimate of residual displacement, while accounting for the collapse resistance performance prior to the repairability evaluation, a probability-based procedure to estimate the residual displacement demands using the nonlinear static analysis (NSA) is developed for single-degree-of-freedom (SDOF) systems. To this end, the energy-based equivalent damping ratio used for NSA is revised to obtain the maximum displacement coincident with the nonlinear time history analysis (NTHA) results in the mean sense. Then, the possible systematic error resulted from RDRs spectra methodology is examined based on the NTHA results of SDOF systems. Finally, the statistical relation between the residual displacement and the NSA-based maximum displacement is established. The results indicate that the energy-based equivalent damping ratio will underestimate the damping for short period ranges, and overestimate the damping for longer period ranges. The RDRs spectra methodology generally leads to the results being non-conservative, depending on post-yield stiffness. The proposed approach emphasizes that the repairability evaluation should be based on the premise of no collapse, which matches with the current performance-based seismic assessment procedure.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.4 no.4
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• pp.141-145
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• 2023

This study surveyed the changes in the proportion of Ecological and Natural Map (ENM) grades in Korea, the distribution ratio of ENM 1st-grade areas by region, and the current status of regional public appeals for the five-year period from 2017 to 2021. The nationwide changes in ENM grades revealed an increase in 1st-grade, 3rd-grade, and separately managed areas but a decrease in the ratio of 2nd-grade areas. Nationwide, Gangwon had the highest distribution ratio of 1st-grade areas, at 46.77%, while Gwangju had the lowest, at 0.05%. In the five-year study period, 383 appeals concerning ENM grades were received and processed. Gangwon had the greatest number of appeals, with 96, while Sejong had the fewest, with 1. A significant correlation was observed between the distribution ratio of 1st-grade areas and public appeals.