• Atmosphere
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• v.26 no.1
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• pp.85-95
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• 2016

In this study, we investigated the variabilities of wind speed of 850 hPa and precipitable water over the East Asia region using the NCEP Final Analysis data from December 2001 to November 2011. A large variance of wind speed was observed in northern and eastern China during the winter period. During summer, the regions of the East China Sea, the South Sea of Japan and the East Sea show large variances in the wind speed caused by an extended North Pacific High and typhoon activities. The large variances in the wind speed in the regions are shown to be correlated with the inter-annual variability of precipitable water over the inland region of windward side of the Korean Peninsula. Based on the investigation, sensitivity tests to the domain size were performed using the WRF model version 3.6 for heavy precipitation events over the Korean Peninsula for 26 and 27 July 2011. Numerical experiments of different domain sizes were set up with 5 km horizontal and 50 levels vertical resolutions for the control and the first experimental run, and 9 km horizontal for the second experimental run. We found that the major rainfalls correspond to shortwave troughs with baroclinic structure over Northeast China and extended North Pacific High. The correlation analysis between the observation and experiments for 1-h precipitation indicated that the second experiment with the largest domain had the best performance with the correlation coefficient of 0.79 due to the synoptic-scale systems such as short-wave troughs and North Pacific High.

• The Journal of Engineering Geology
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• v.32 no.2
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• pp.257-270
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• 2022

This study evaluated the hydraulic factors contributing to the decreasing groundwater levels across Jeju island. Time-series data for groundwater level, precipitation, and groundwater usage and information on land use were acquired, and the correlations among them were analyzed to evaluate the causes of the decreasing groundwater. The effects of precipitation and groundwater usage on the fluctuations of groundwater level were quantified using response surface analysis and sensitivity analysis, and methods for groundwater quantity management by region were proposed. The results showed that the rate of groundwater decrease in the western region was larger than that in the eastern region. For the eastern region, the influence of precipitation was large and the rate of decrease in the groundwater level was relatively small. The geological formation of this part of the island and continuous seawater intrusion suggest that although the absolute amount of groundwater extracted for use was large, the decrease in the groundwater level was not seen to be great due to an increase in pressure by seawater intrusion. Overall, precipitation and groundwater usage had the greatest effect on the amount of groundwater in the western region, and thus their data would be most useful for informing groundwater management, whereas other factors (e.g., sea level and the location of the freshwater-seawater transition zone) must be considered when understanding Jeju's eastern region. As the characteristics of groundwater level fluctuations in the eastern and western regions are distinct, an optimal management plan for each region should be proposed to ensure the efficient management of groundwater quantity.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.2-11
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• 2006

In the processes of hydrological cycle, when precipitation reaches the ground surface, water may become surface runoff or infiltrate into soil and then possibly further percolate into groundwater aquifer. A part of the water is returned to the atmosphere through evaporation and transpiration. Soil moisture dynamics driven climate fluctuations plays a key role in the simulation of water transfer among ground surface, unsaturated zone and aquifer. In this study, a one-layer canopy and a four-layer soil representation is used for a coupled soil-vegetation modeling scheme. A non-zero hydraulic diffusivity between the deepest soil layer modeled and groundwater table is used to couple the numerical equations of soil moisture and groundwater dynamics. Simulation of runoff generation is based on the mechanism of both infiltration excess overland flow and saturation overland flow nested in a numerical model of soil moisture dynamics. Thus, a comprehensive hydrological model integrating canopy, soil zone and aquifer has been developed to evaluate water resources in the plain region of Huaihe River basin in East China and simulate water transfer among precipitation, surface water, soil moisture and groundwater. The newly developed model is capable of calculating hydrological components of surface runoff, evapotranpiration from soil and aquifer, and groundwater recharge from precipitation and discharge into rivers. Regional parameterization is made by using two approaches. One is to determine most parameters representing specific physical values on the basis of characterization of soil properties in unsaturated zone and aquifer, and vegetations. The other is to calibrate the remaining few parameters on the basis of comparison between measured and simulated streamflow and groundwater tables. The integrated modeling system was successfully used in the Linhuanji catchment of Huaihe plain region. Study results demonstrate that (1) on the average 14.2% of precipitation becomes surface runoff and baseflow during a ten-year period from 1986 to 1995 and this figure fluctuates between only 3.0% in drought years of 1986, 1988, 1993 and 1994 to 24.0% in wet year of 1991; (2) groundwater directly deriving from precipitation recharge is about 15.0% t of the precipitation amount, and (3) about half of the groundwater recharge flows into rivers and loses through evaporation.

• Resources Recycling
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• v.28 no.5
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• pp.42-50
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• 2019

In this study, the precipitation reaction of vanadium and ammonium chloride in aqueous solution was investigated in order to recover vanadium. Ammonium metavanadate having a crystal structure of [$NH_4VO_3$] was precipitated from aqueous solution containing vanadium at pH 9.2 ~ 9.4, and ammonium polyvanadate having a crystal structure of [$(NH_4)_2V_6O_{16}$] was precipitated when the pH of the aqueous solution containing vanadium was adjusted with sulfuric acid. Ammonium polyvanadate [$(NH_4)_2V_6O_{16}$] precipitated at a temperature of $80{\sim}90^{\circ}C$ and pH 2, and at a temperature of $40^{\circ}C$ and pH 6 ~ 8 of aqueous solution. In the acidic region of aqueous solution pH 2, the vanadium content of the aqueous solution should be at least 3,000 mg/L and the precipitation temperature should be maintained at $80^{\circ}C$ or higher in order to obtain a precipitation ratio of 99% or more. When the ammonium vanadate was precipitated in the alkaline region, the vanadium content was more than 10,000 mg/L and the precipitation temperature was maintained at $40^{\circ}C$ to increase the precipitation ratio. Aluminum was not precipitated regardless of the vanadium content and pH of the aqueous solution. However, the iron component reacts with ammonium chloride to precipitate into ammonium jarosite. Therefore, Fe component must be preferentially removed in order to increase the recovery of vanadium.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.417-428
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• 2005

The seasonal variation and frequency of precipitation phenomenon of the Korean Peninsula in summer show strong local weather phenomena because of its topographical and geographical factors in the northeastern area of Asia. The characteristics of the prevailing weather patterns in summer precipitation in Korea have great influences on the variation patterns and the appearances over a ten-day period during the summer precipitation. The purpose of this paper is to induce variation patterns over a period 10 days during the summer precipitation, clarify the variations of their space scales, and study the subdivision of precipitation regions in Korea according to the combinations of precipitation amounts and variation pattern during the period, using the mean values during the years $1991\~2003$ at 78 stations in Korea. The classified precipitation of a period of 10 days of summer precipitation, and the principal component vector and the amplitude coefficient by the principal component analysis were used for this study. The characteristics of variation pattern over the ten-day period can be chiefly divided into two categories and the accumulated contributory rate of these is $64.3\%$. The variation patterns of summer precipitation during period of 10 days in Korea are classified into 9 types from A to K. In addition, regional divisions of summer precipitation in Korea can be classified into 17 types.

• Journal of the Korean Institute of Navigation
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• v.18 no.1
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• pp.23-30
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• 1994

By use of the Climatological Report(1982~1991) and the Marine Casualty Report(1982`1992), marine casualties caused by meteorological factors and climatic characteristics along Korean coast were analysed. Marine casualty by meteorological factors can be classified into three kinds such as collision, aground and sinking. On the whole collision was mainly caused by dense fog and heavy precipitation, and aground and sinking was caused by strong wind and high sea. As results of analysis of the distribution of wind, fog and precipitation at major ports in Korea, climatic characteristics along Korean coast are as follows. in the eastern coast, wind was relatively weak and fog was not so frequently formed, while strong wind blew all the year round and fog appeared from April to August in Ulleung Island. In the southern coast, the wind was strong in both winter and summer, fog formed frequently in late spring through mid-summer and heavy precipitation was in summer. Typhoon affecting Korea was usually passing this area to the East Sea. In the western coast, strong wind was prevailing in winter at southern region and fog was formed very frequently throughout the year.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.2
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• pp.179-187
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• 1996

Sampling of precipitation occurred at Woongchon in Choongnam from the period between May 1994 and April 1995 was made, and analysis on the data was carried out on observed pH values of the precipitations. It was found that weighted mean pH values were .sim. 4.8 and that acid rain occurred at the site of the Yellow Sea's coastal area. The results agree well with the earlier observations made at other sites of a background monitoring network. The annual values observed at the background monitoring sites were too low in comparison with the mean pH values (5.3 .sim. 5.9) obtained from urban stations of the Ministry of Environment. It was observed that values of pH in rain water often changed with time during the event of precipitation, and the low values usually depended on an airflow and a cyclone that originated in the source region.

• The Korean Journal of Ecology
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• v.20 no.2
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• pp.95-102
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• 1997

Ring width chronologies of blue pine (pinus wallichiana) from two mesic sites, Kanasar(2, 400 m) and Gangotri(3, 000 m), in the western Himalayan region. India were developed to understand tree growth-climate relationship and its applicability in proxy climate studies. The resoponse function analyses of the two chronologies show that the site conditions play an important role in modulating the effect of climatic variables on tree growth. Winter temperature, prior to the growth year, has been found to play positive influence on blue pine growth at both sites. Summer temperature also has very similar response except for June and August. June temperature has negative influence at the lower in contrary to at the higher site. Low August temperature favors tree growth to precipitation has been found to vary which could be due to different precipitation regime at the two sites. Winter precipitation is important for tree growth at the higher, whereas summer at the lower sits. The present study suggests that the tree ring materials of blue pine from the temperate Himalayan regions could be used to develop chronologies for the reconstruction of seasonal climatic variables.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.94.2-94.2
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• 2013

We studied the precipitation of magnetospheric energetic electrons into the Earth's atmosphere during magnetic storm times using precipitating electron flux data from the MEPED on board the NOAA Polar Orbiting Environmental Satellites (POES) low.altitude satellite, NOAA-16. We identified a total of 84 storm events between 2001 and 2012 using SYM-H index. We have done a superposition of precipitating electron fluxes for each of three energy ranges (i.e., e1: > 30 keV, e2: > 100 keV, e3: > 300 keV) for the identified storm times. The results show that the fluxes start to increase before the main phase of storm for all energy ranges and reach a maximum level just before the time of SYM-H minimum value. The precipitation timescales are energy-dependent, being shorter for lower energy, ~4.67 hours for e1, ~7.93 hours for e2 and ~26.5 hours for e3. The precipitating fluxes decline during the recovery phase of the storms. We examined the L shell dependence of the precipitating electron flux during the main phase. We found that statistically the precipitation fluxes are dominantly seen at L of ~ 3-4 or higher. This L value roughly corresponds to the plasmapause location during the main phase. Thus the results imply that the electron precipitation mainly occurs outside of the plasmapause. In addition, we classified the storm events by their strength and examined the dependence of precipitation on storm intensity. We found that the electron precipitation occurs on a faster time scale and penetrate into inner L shell region for a stronger storm.

• Asia-Pacific Journal of Atmospheric Sciences
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• v.54 no.4
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• pp.587-598
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• 2018

The impacts of aerosol loading on surface precipitation from mid-latitude deep convective systems are examined using a bin microphysics model. For this, a precipitation case over north central Mongolia, which is a high-altitude inland region, on 21 August 2014 is simulated with aerosol number concentrations of 150, 300, 600, 1200, 2400, and $4800cm^{-3}$. The surface precipitation amount slightly decreases with increasing aerosol number concentration in the range of $150-600cm^{-3}$, while it notably increases in the range of $600-4800cm^{-3}$ (22% increase with eightfold aerosol loading). We attempt to explain why the surface precipitation amount increases with increasing aerosol number concentration in the range of $600-4800cm^{-3}$. A higher aerosol number concentration results in more drops of small sizes. More drops of small sizes grow through condensation while being transported upward and some of them freeze, thus increasing the mass content of ice crystals. The increased ice crystal mass content leads to an increase in the mass content of small-sized snow particles largely through deposition, and the increased mass content of small-sized snow particles leads to an increase in the mass content of large-sized snow particles largely through riming. In addition, more drops of small sizes increase the mass content of supercooled drops, which also leads to an increase in the mass content of large-sized snow particles through riming. The increased mass content of large-sized snow particles resulting from these pathways contributes to a larger surface precipitation amount through melting and collision-coalescence.