• Journal of Korea Water Resources Association
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• v.47 no.7
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• pp.643-656
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• 2014

The homogeneity analysis of temporal (monthly, seasonal and annual) climate aridity index trend was accomplished for 43 climate measurement stations in South Korea. Furthermore, 43 stations were grouped into 9 different regions and the temporal and regional homogeneity of climate aridity index trends in each region and entire 9 regions were analyzed. For analysis, monthly, seasonal and annual climate aridity indexes of 43 study stations were estimated using precipitation and potential evapotranspiration calculated from FAO Penman-Monteith equation. The Mann-Kendall statistical test for significant trend was accomplished using the estimated climate aridity indexes and the results of trend test (Z scores) were used to analyze the temporal and regional homogeneity of climate aridity index trends. The study results showed the temporal and regional homogeneity of climate aridity index trends for individual and entire 9 regions. However, the homogeneity and the extent of aridity index trend showed different patterns temporally and regionally.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.115-125
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• 2012

The comparison between the spatial and temporal variability of aridity index, precipitation effectiveness and runoff during El-Nino and La-Nina periods and that of the normal period was conducted to evaluate the regional impacts of El-Nino, La-Nina in hydrologic variables. Aridity index and precipitation effectiveness were estimated using 59 nationwide weather stations data and runoff data of WAMIS were used. The ratio of the difference between El-Nino, La-Nina year value and that of normal year was analyzed. Temporal variation demonstrated that aridity index, precipitation effectiveness and run-off discharge increase in March, April, August, November, December and decrease in February, June, September, October according to El-Nino effect. Aridity index, precipitation effectiveness and run-off discharge increase in March, May, September and decrease in June, August, November, December according to La-Nina effect. The spatial variation of those variables analyzed for different basins showed that impacts in the Han river basin relatively higher than that of other basins.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.146-146
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• 2019

The aridity index, which is determined as the ratio of potential evapotranspiration to precipitation, is one of key parameters in drought characterization. Whereas the evaporative index, which is defined as the ratio of actual evapotranspiration to precipitation, represents the fraction of available water consumed by the evapotranspiration process. This study investigates variation of the aridity and evaporative indexes due to climate change during the 21st century in South Korea. Estimations of the aridity and evaporative indexes are obtained using SWAT mode based on ensemble of 13 different GCMs over 5 large basins of South Korea for 2 RCP scenarios (RCP 4.5 and RCP 8.5). The results shows the opposite trends of the two indexes, where the aridity index is projected as always increase, while the evaporative index is expected to decrease in all of 3 future period (2011-1940, 1941-1970, 1971-2099). The estimated results also suggest that land cover influenced significantly evapotranspiration along with the change of climate. The study indicates that South Korea will be facing with a high risk of water scarcity in future due to climate change, which is seriously challenging for water planing and management in the country.

• 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.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.613-627
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• 2013

In this study, to understand the May aridity condition of each region for the year of the worst drought on record in each duration (1-, 3-, 6-, 12-, 24 months), monthly climate data recorded from 1973 to 2006 at 53 climatological stations in South Korea were used to estimate the FAO Penman-Monteith reference potential evapotranspiration (RET). Monthly precipitation and RET were used to estimate P/RET as aridity index and variation index (VI) of P/RET, and these indexes are compared with SPI (Standard Precipitation Index). Fifty three climatological stations were grouped into 20 regions, so that May aridity conditions of 20 regions were studied. Furthermore, regional trend of May aridity index was studied by applying Mann-Kendall trend analysis, Spearman rank test, and Sen's slope estimator. The study results show that variation index (VI) of P/RET and SPI have close correlation. Throughout the country, as the duration is shorter, May aridity was more severe. In case of 3-month and 6-month duration, most of region show significant or non-significant decreasing trend of aridity index. However, no region show significant decreasing trend of aridity index in case of 12-month and 24-month duration.

• Journal of Ecology and Environment
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• v.46 no.1
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• pp.76-84
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• 2022

Background: Climate and livestock grazing are key agents in determining current Mongolian steppe vegetation communities. Together with plant coverage or biomass, palatability of steppe community is regarded as a useful indicator of grassland degradation, in particular, at grazing hotspots in arid and semi-arid grasslands. This study analyzed relationships between livestock grazing pressure and steppe vegetation palatability at three summer pastures with different aridity (dry, xeric, and mesic) and livestock numbers (1,100, 1,800, and 4,100 sheep units, respectively). At each site, it was surveyed coverage, biomass, and species composition of different palatability groups (i.e., palatable [P], impalatable [IP], and trampling-tolerant [TT]) along a 1-km transect from grazing hotspots (i.e., well) in every July from 2015 to 2018. Results: In results, total vegetation coverage increased with wetness, 7 times greater at mesic site than dry one in averages (33.1% vs. 4.5%); biomass was 3 times higher (47.1 g m^-2 vs. 15.7 g m^-2). Though P was the dominant palatability group, the importance of IP in total coverage increased with aridity from mesic (0.6%) to dry (40.2%) sites. Whereas, TT increased with livestock numbers across sites. Locally, IP was observed more frequently near the wells and its spatial range of occurrence becomes farther along the transects with aridity across sites from mesic (< 100 m) to dry (< 700 m from the well). Conclusions: Our results showed that the importance of IP and its spatial distribution are different at both local and regional scales, indicating that the palatability parameters are sensitive to discern balance between selective-grazing demand and climate-driven foraging supply in Mongolian rangelands.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.193-193
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• 2017

Trend analysis can enhance our knowledge of the dominant processes in the area and contribute to the analysis of future climate projections. The results of previous studies in South Korea showed that southeast regions of Korea had the highest value of evapotranspiration. Thereby, it is of interest to determine the trend analysis in hydrological variables in this area. In this study, the recent 35 year trends of precipitation, reference evapotranspiration, and aridity index in monthly and annual time scale will be analyzed over three stations (Pohang, Daegu, and Pusan) of southeast Korea. After removing the significant Lag-1 serial correlation effect by pre-whitening, non-parametric statistical Mann-Kendall test was used to detect the trends. Also, the slope of trend of the Mann-Kendall test was determined by using Theil-Sen's estimator. The results of the trend analysis of reference evapotranspiration on the annual scale showed the increasing trend for the three mentioned stations, with significant increasing trend for Pusan station. The results obtained from this research can guide development if water management practices and cropping systems in the area that rely on this weather stations. The approaches use and the models fitted in this study can serve as a demonstration of how a time series trend can be analyzed.

• Journal of Environmental Science International
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• v.16 no.4
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• pp.399-407
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• 2007

The characteristics of meteorological conditions relevant to Asian dust (AD) outbreaks and their occurrence frequencies were analyzed in four source regions (R1 to R4) during spring months (March to May) of 1995-2002. Moreover, the concentration variations of AD (e.g., $PM_{10}$) observed in Korea were investigated during the study period. In the relationship between AD outbreaks and three meteorological parameters (i.e., air temperature, wind speed, and aridity), the largest AD outbreaks in April (${\sim}250$ observations) mostly occurred in R2 when air temperature ranging from 10.0 to $15^{\circ}C$ and surface wind speed from 7 to $9m\;s^{-1}$ were recorded. Moreover, the aridity ($\geq4$) in April was significantly high in R2 with the maximum frequency of AD outbreaks (i.e., 206 observations). On the other hand, the number (percentage) of days belonging to AD events observed in five Korean cities were found to be 116 (44%), 121 (46%), and 26 days (10%) in March, April, and May, respectively. The mean $PM_{10}$ concentrations were found to range from 150 to 220, 150 to 200, and 95 to $120{\mu}g\;m^{-3}$ in March, April, and May, respectively. Consequently, this implied that the AD events in Korea were found to be gradually frequent in early spring and to be affected from the large AD outbreaks observed in the source regions.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.4
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• pp.51-60
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• 2017

Bottom ash(BA) from coal-fired power plants is burnt and remaining ash at high temperature. Since the BA is baked at high temperature, it is considered to be the same function as the elvan. Nowadays, the demand for mortar with far infrared rays, antibacteria, antifungus, deodorization, aridity and humidity function is increasing as the materials such as Hwangtoh(yellow soil) and elvan rather than general mortar. As a result of comparing the functionality of eco-friendly bio BA mortar with that of general mortar, the far infrared ray emissivity is about $0.02{\times}10^2W/m^2$ more and the deodorization function is about 26% or more. Even in the case of humidity control, BA motors showed about 1.8 times higher than general mortar, and more than 10% higher than the "good" standards of moisture absorption and damp proofing construction materials established by the Ministry of Land, Transport and Maritime Affairs.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.2
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• pp.82-94
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• 2014

The purpose of this study is to investigate the cause of increasing dry zones through analyzing relationships between land cover and Vegetation Temperature Condition Index(VTCI) using Landsat 4-5 TM satellite images in Central Dry Zones of Myanmar. As a result of land cover classifications, while vegetation areas gradually decrease, residential area and cropland were increased. VTCI analysis shows that region (a) showed a gradual decrease in the area of severely arid, and increase in the area of moderate dry and wet, which sums up to a slight decrease in aridity. Region (b) also showed to increase in dry areas and severe aridity. The result of relational analysis between VTCI and land cover change showed high ratio of land cover change, from severe arid area to forest and residential farmland. The average VTCI decreased in the changed land covers, which indicates the relationship between aridity and land cover change and a gradual increase in the arid area was identified.