• Journal of the Korean Geographical Society
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• v.43 no.5
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• pp.681-700
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• 2008

In this study, the spatial and temporal patterns of changes in means and extreme events of temperature and precipitation across the Republic of Korea over the last 35 years (1973-2007) are examined. Over the study period, meteorological winter (December-February) mean minimum (maximum) temperature has increased by $+0.54^{\circ}C$/decade ($+0.6^{\circ}C$/decade), while there have been no significant changes in meteorological summer (June-August) mean temperatures. According to analyses of upper or lower $10^{th}$ percentile-based extreme temperature indices, the annual frequency of cool nights (days) has decreased by -9.2 days/decade (-3.3 days/decade), while the annual frequency of warm nights (days) has increased by +4.9 days/decade (+6.8 days/decade). In contrast, the increase rates of summer warm nights (+8.0 days/$^{\circ}C$) and days (+6.6 days/$^{\circ}C$) relative to changes in summer means minimum and maximum temperatures means are greater than the decreasing rates of winter nights (-5.2 days/$^{\circ}C$) and days (-4.3 days/$^{\circ}C$) relative to changes in winter temperatures. These results demonstrate that seasonal and diurnal asymmetric changes in extreme temperature events have occurred. Moreover, annual total precipitation has increased by 85.5 mm/decade particularly in July and August, which led to the shift of a bimodal behavior of summer precipitation into a multi-modal structure. These changes have resulted from the intensification of heavy rainfall events above 40mm in recent decades, and spatially the statistically-significant increases in these heavy rainfall events are observed around the Taebaek mountain region.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.518-527
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• 2020

The establishment of a green remodeling strategy is focused on technology, so the necessity of establishing a customized strategy considering the field situation has emerged. This paper examined the technology strategy through sensitivity analysis as a methodology for guiding strategy. For a 90-square-meter detached house, nine models of the construction standards of pre-1980s, 1984, and 2010 in Seoul, Daejeon, and Busan were assessed using the optimization method that combines the energy plus engine and the ModeFrontier. Sensitivity analysis was performed, and the remodeling strategy priority was derived. For pre-1980 models, the strategy for enhancing the roof insulation performance had a significant priority. The SHGC values of the windows were found to have the next highest priority regardless of the region and the time of completion, showing that the performance standard, including the SHGC, needs to be expanded. The possibility of remodeling while maintaining the existing geometry was confirmed because the adjustment of the window wall ratio accompanying large-scale demolition works has low priority. The priorities of technology strategies in each case showed very different patterns, suggesting the possibility of establishing a remodeling strategy by a comprehensive evaluation along with economics and constructability analysis.

• Journal of Korea Water Resources Association
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• v.51 no.5
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• pp.425-438
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• 2018

Existing studies that analyze the causes and effects of water circulation use mostly rainfall - runoff models, which requires much effort in model development, calibration and verification. In this study, hydrological sensitivity analysis which can separate quantitatively the impacts by natural factors and anthropogenic factor was applied to the Hwacheon dam upper basin from 1967 to 2017. As a result of using various variable change point detection methods, 1999 was detected as a statistically significant change point. Especially, based on the hydrological sensitivity analysis using 5 Budyko based functions, it was estimated that the average inflow reduction amount by Imnam dam construction was $1.890\;billion\;m^3/year$. This results in this study was slightly larger than the those by existing researchers due to increase of rainfall and decrease of Hwacheon dam inflow. In future, it was suggested that effective water management measures were needed to resolve theses problems. Especially, it can be suggested that the monthly or seasonal analysis should be performed and also the prediction of discharge for future climate change should be considered to establish resonable measures.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.5
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• pp.430-436
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• 2015

Numerical air quality forecasting suffers from the large uncertainties of input data including emissions, boundary conditions, earth surface properties. Data assimilation has been widely used in the field of weather forecasting as a way to reduce the forecasting errors stemming from the uncertainties of input data. The present study aims at evaluating the effect of input data on the air quality forecasting results in Korea when data assimilation was invoked to generate the initial concentrations. The forecasting time was set to 36 hour and the emissions and initial conditions were chosen as tested input parameters. The air quality forecast model for Korea consisting of WRF and CMAQ was implemented for the test and the chosen test period ranged from November $2^{nd}$ to December $1^{st}$ of 2014. Halving the emission in China reduces the forecasted peak value of $PM_{10}$ and $SO_2$ in Seoul as much as 30% and 35% respectively due to the transport from China for the no-data assimilation case. As data assimilation was applied, halving the emissions in China has a negligible effect on air pollutant concentrations including $PM_{10}$ and $SO_2$ in Seoul. The emissions in Korea still maintain an effect on the forecasted air pollutant concentrations even after the data assimilation is applied. These emission sensitivity tests along with the initial condition sensitivity tests demonstrated that initial concentrations generated by data assimilation using field observation may minimize propagation of errors due to emission uncertainties in China. And the initial concentrations in China is more important than those in Korea for long-range transported air pollutants such as $PM_{10}$ and $SO_2$. And accurate estimation of the emissions in Korea are still necessary for further improvement of air quality forecasting in Korea even after the data assimilation is applied.

• Journal of Korea Water Resources Association
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• v.40 no.8
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• pp.585-600
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• 2007

The hydrologic cycle and BOD pollutant loads of all sub-watersheds were analyzed using HSPF (Hydrological Simulation Program-Fortran). At first, sensitivity analyses to water quantity (peak discharge and total volume) and quality (BOD peak concentrations and total loads) were conducted and some critical Parameters were selected. For more precise simulation, the study watershed was divided into four parts according to the landuse characteristics and used climate data and so calibrated and verified respectively. It was found that as the urban area ratio increases in the downstream direction, baseflow decreases (11.1 % $\rightarrow$ 5.0%) and the ratio of direct runoff volume(42.5 % $\rightarrow$ 56.9 %), BOD concentration (3.3 mg/L $\rightarrow$ 15.0 mg/L) and unit loads (55.4 kg/ha/year $\rightarrow$ 354.5 kg/ha/year) increase.

• Atmosphere
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• v.21 no.4
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• pp.391-404
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• 2011

This study investigates the impact of cumulus parameterization scheme (CPS) with different horizontal grid sizes on the simulation of the local heavy rainfall case over the Korean Peninsula. The Weather Research and Forecasting (WRF)-based real-time forecast system of the Joint Center for High-impact Weather and Climate Research (JHWC) is used. Three CPSs are used for sensitivity experiments: the BMJ (Betts-Miller-Janjic), GD (Grell-Devenyi ensemble), and KF (Kain-Fritsch) CPSs. The heavy rainfall case selected in this study is characterized by low-level jet and low-level transport of warm and moist air. In 27-km simulations (DM1), simulated precipitation is overestimated in the experiment with BMJ scheme, and it is underestimated with GD scheme. The experiment with KF scheme shows well-developed precipitation cells in the southern and the central region of the Korean Peninsula, which are similar to the observations. All schemes show wet bias and cold bias in the lower troposphere. The simulated rainfall in 27-km horizontal resolution has influence on rainfall forecast in 9-km horizontal resolution, so the statements on 27-km horizontal resolution can be applied to 9-km horizontal resolution. In the sensitivity experiments of CPS for DM3 (3-km resolution), the experiment with BMJ scheme shows better heavy rainfall forecast than the other experiments. The experiments with CPS in 3-km horizontal resolution improve rainfall forecasts compared to the experiments without CPS, especially in rainfall distribution. The experiments with CPS show lower LCL(Lifted Condensation Level) than those without CPS at the maximum rainfall point, and weaker vertical velocity is simulated in the experiments with CPS compared to the experiments without CPS. It means that CPS suppresses convective instability and influences mainly convective rainfall. Consequently, heavy rainfall simulation with BMJ CPS is better than the other CPSs, and even in 3-km horizontal resolution, CPS should be applied to control convective instability. This conclusion can be generalized by conducting more experiments for a variety of cases over the Korean Peninsula.

• Journal of Environmental Health Sciences
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• v.39 no.6
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• pp.492-504
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• 2013

Objectives: This analysis seeks to evaluate the impact of environmental health factors (EHF; e.g. hospital beds per capita, employees of medical institutions) on extreme-heat vulnerability assessment in Busan Metropolitan City during 2006-2010. Methods: According to the vulnerability concept suggested by the Intergovernmental Panel on Climate Change (IPCC), extreme-heat vulnerability is comprised of the categories of Exposure, Sensitivity, and Adaptive Capacity (including EHF). The indexes of the Exposure and Sensitivity categories indicate positive effects, while the Adaptive capacity index indicates a negative effect on extreme-heat vulnerability. Variables of each category were standardized by the re-scaling method, and then each regional relative vulnerability was computed with the vulnerability index calculation formula. Results: The extreme-heat vulnerability index (EVI) excepting EHF was much higher in urban areas than in suburban areas within the metropolitan area. When EHF was considered, the difference in the EVI between the two areas was reduced due to the increase of the Adaptive capacity index in urban areas. The low EVI in suburban areas was induced by a dominant effect of natural environmental factors (e.g. green area) within the Adaptive capacity category. Conclusions: To reduce the vulnerability to extreme heat in urban areas, which were more frequently exposed to extreme heat than others areas, public health and natural environments need to be improved in sensitive areas.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.178-186
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• 2020

In this study, the elasticity was calculated and sensitivity analysis was performed using air-water temperature data of the major tributaries of the Nakdong River. We developed a nonparametric elasticity analysis technique capable of estimating the confidence interval for elasticity and verifying the hypothesis, and examined its applicability compared to the existing method using the median value. It is analyzed that the elasticity of winter is low and the elasticity of summer and autumn is high, so that the fluctuation of water temperature and water quality according to the fluctuation of air temperature is large. The spatial elasticity tends to be low in the Geumho River area, which is influenced by artificial factors such as sewage treatment plant effluent, small and medium-sized livestock wastewater, and small-scale factory wastewater. Since the elasticity of major tributaries of the Nakdong River is over weak and is reasonable at a significance level of 5%, it was analyzed that the air-water temperature fluctuation caused by climate changes is large.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.6
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• pp.31-40
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• 2019

In order to implement practical alternatives to proactively cope with the agricultural drought, the potential vulnerability of irrigation pumping stations to agricultural drought was quantitatively evaluated. Data for the 124 pumping stations which are correlatable to the three proxy variables, i.e. exposure, sensitivity, and adaptive capacity was collected by the Korea Rural Community Corporation, and then standardized considering distribution of each data set. Finally, the vulnerability index was calculated by multiplying the weights determined by the expert survey. The results showed that the vulnerability index ranged from 0.709 to 0.331 and the most vulnerable pumping stations such as Judam, Wongoo and Jinahn were mostly located in Gyeongbuk province likely because of the climatological characteristics with high temperature and low rainfall around this area. In addition, it was found that the adaptive capacity was a dominant factor comparing to exposure or sensitivity proxy variables in contributing to the vulnerability. It is therefore recommended that more practical alternatives should be employed to effectively reduce the vulnerability of an individual pumping station to agricultural drought. Furthermore, the corresponding data related to adaptive capacity should be systematically organized and managed at a field level to design reliable adaptation strategies.

• Korean Journal of Environmental Biology
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• v.33 no.3
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• pp.345-351
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• 2015

This study was conducted to find out the methodology of carbon budget assessment among soil, atmosphere and plant. Soil respiration, net ecosystem productivity of herbs and net ecosystem productivity of woody plants have been measured in 30 years old pear orchard at Naju. Closed Dynamic Chamber (CDC) method was used to measure soil respiration and net ecosystem productivity of herbs. Net ecosystem productivity of woody plant (pear) was determined by eddy covariance method using the EddyPro (5.2.1) program. As for soil respiration, $429.1mgCO_2m^{-2}h^{-1}$ was released to atmosphere and sensitivity of soil temperature ($Q_{10}$) was 2.3. In case of herbs, respiration was superior to photosynthesis during measurement period. From 20 to 24 Jun 2015, the sum of absorbed and released $CO_2$ by herb's photosynthesis and respiration was $156.1mgCO_2m^{-2}h^{-1}$. Woody plants showed the $680.1mgCO_2m^{-2}h^{-1}$ of absorption by photosynthesis. In a farm scale, the sum of soil respiration, and net ecosystem productivity of herbs and woody plants was $0.04tonCO_2ha^{-1}$ during the measurement period, and it showed that pear orchard act as a $CO_2$ sink. This study using various approaches is expected to present a methodology for evaluating the carbon budget of perennial woody crop plantations.