• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.269-273
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• 2011

본 연구는 도암댐 상류 고랭지 농업지역의 이른 봄철 융설에 의해 발생되는 비점오염 물질의 배출 특성을 규명하고자 수행하였다. 연구는 2010년 2월 중순부터 4월 말까지 수행하였다. 연구지역에서는 2009년 11월 2일부터 2010년 4월 29일까지 눈이 내렸으며, 일 최대 적설량은 2월 11일에 기록된 59.3 cm이고, 총 적설량은 372.1 cm로 나타났다. 연구결과 융설에 의해 발생되는 단위 면적당 유량은 $77.05\;m^3$/ha/day로서 겨울철 평시 유량 $26.99\;m^3$/ha/day에 비해 두배 가까이 증가하였다. 유량의 변화는 기온의 영향을 많이 받는 것으로 나타났으며, 유량의 변화는 탁도와 SS 그리고 $COD_{Mn}$의 농도 변화에 영향을 주는 것으로 조사되었다. 오염물질 항목 중 SS와 COD의 유량가중평균농도는 각각 986.0 mg/L와 16.3 mg/L로서 겨울철 평시 농도보다 크게 증가하였는데, 이는 융설시 발생한 유출수에 의해 미세한 토양입자의 유실과 함께 오염물질도 배출된 결과로 판단된다. 그러나 T-N과 T-P의 농도는 큰 변화가 없는 것으로 조사되었다. 본 연구결과에 기초할 때, 담수호 상류에 위치한 고랭지 지역에서는 겨울철 적설량이 많고 융설에 의한 수질오염 문제가 하는 것으로 판단된다. 따라서 해빙기 융설로 인해 발생되는 비점오염 물질의 정량화에 대한 연구가 체계적이고 지속적으로 수행될 필요가 있다. 특히 우리나라의 겨울철 적설량과 기온은 연도별로 많은 편차가 있고, 연구결과 다량의 오염물질이 배출되기 때문에 융설에 대한 연구는 반드시 수행되어야 할 것으로 판단된다.

• Journal of the Korean association of regional geographers
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• v.8 no.4
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• pp.468-479
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• 2002

This study attempts to characterize Taebaek mountainous region as a natural unit, relating to morphoclimatic milieu and landform development patterns of the mountains of each lithologic type. In the case of granitic mountains of Nothern parts of this region, the slopes presents more or less steep or irregular profile because of abundant microforms of exposed bedrocks and blocks. The development of such landscape is essentially due to differential weathering, associated with difference of joint density. In the case of gneissic mountains, the slopes are well regularized straight steep ones, due not only to generalized superficial weathering but also to massmovement of weathered materials. In the Middle parts of this region, especially in Taegwallyong area, with frequent alternations both of freezing-thawing and of snow accumulation-melting, the roles played by cryo-nival processes proved to be important in weathering of granite as well as in morpho-pedogenesis. In this area, weathered mantle, developed by cryogenic activity under humid condition of nival environment, covered almost all over the slopes. Although Southern parts of this region consist of limestone, on the mountainous volume, distribution of Karst forms are limited while predominate none karst forms such as cockpit type peaks, V-shaped type valleys dissecting steep slopes covered with thin deposits in thickness containing rock debris.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.2
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• pp.257-262
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• 2019

In order to investigate hydrological behavior of the east coast snowfall in February 2014, this study analyzed the changes of the hydrological components due to the snowmelt in the Ssangcheon watershed nearby Sokcho city. The temporal changes of hydrological components through snowfall and snowmelt processes were simulated using SWAT-MODFLOW. As a result of the analysis, snow accumulated until February is fully melted from the late March, 2014, and the stream discharge of April is more than doubled compared to the case of not considering snowmelt. The soil moisture also increased by up to 21 % due to the melting and the groundwater level rose by about 40 cm until the end of April. Thus, the heavy snowfall in February 2014 is considered to play an important role in securing water resources in this region.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.372-372
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• 2021

The agriculture sector plays a vital role in the economy of Pakistan by contributing about 20% of the GDP and 42% of the labor force. Rivers from the top of Himalayas are the major water resources for this agriculture sector. Recent reports have found that Pakistan is one of the most vulnerable country to climate change that can cause water scarcity which is a big challenge to the communities. Previous studies have investigated the impact of climate change on the trend of streamflow, but the understanding of seasonal change in the regional hydrologic regimes remained limited. Therefore, a better understanding of the seasonal hydrologic change will help cope with the future water scarcity issue. In this study, we used the daily stream flow data for four major river basins of Pakistan (Chenab, Indus, Jhelum and Kabul) over 1962 - 2019. Utilizing these daily river discharge data, we calculated the winter-spring center time and the summer-autumn center times. In this study Winter-spring center time (WSCT) is defined as the day of the calendar year during which half of the total six months (Jan-Jun) discharge volume was exceeded. Results show that the four river basins experienced a statistically significant decreasing trend of WSCT, that is the center time keeps coming earlier compared to the past. We further used the Climate Research Unit (CRU) climate data comprising of the average temperature and precipitation for the four basins and found that the increasing average temperature value causes the early melting of the snow covers and glaciers that resulted in the decreasing of 1^st center time value by 4 to 8 days. The findings of this study informs an alarming situation for the agriculture sector specifically.

• Journal of the Korean earth science society
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• v.33 no.2
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• pp.139-147
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• 2012

Mongolia's solar-meteorological resources map has been developed using satellite data and reanalysis data. Solar radiation was calculated using solar radiation model, in which the input data were satellite data from SRTM, TERA, AQUA, AURA and MTSAT-1R satellites and the reanalysis data from NCEP/NCAR. The calculated results are validated by the DSWRF (Downward Short-Wave Radiation Flux) from NCEP/NCAR reanalysis. Mongolia is composed of mountainous region in the western area and desert or semi-arid region in middle and southern parts of the country. South-central area comprises inside the continent with a clear day and less rainfall, and irradiation is higher than other regions on the same latitude. The western mountain region is reached a lot of solar energy due to high elevation but the area is covered with snow (high albedo) throughout the year. The snow cover is a cause of false detection from the cloud detection algorithm of satellite data. Eventually clearness index and solar radiation are underestimated. And southern region has high total precipitable water and aerosol optical depth, but high solar radiation reaches the surface as it is located on the relatively lower latitude. When calculated solar radiation is validated by DSWRF from NCEP/NCAR reanalysis, monthly mean solar radiation is 547.59 MJ which is approximately 2.89 MJ higher than DSWRF. The correlation coefficient between calculation and reanalysis data is 0.99 and the RMSE (Root Mean Square Error) is 6.17 MJ. It turned out to be highest correlation (r=0.94) in October, and lowest correlation (r=0.62) in March considering the error of cloud detection with melting and yellow sand.

• Korean Journal of Remote Sensing
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• v.34 no.2_1
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• pp.237-248
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• 2018

The vertical distribution of hydrometeor before precipitation near the cloud base has been analyzed using a scanning lidar, rawinsonde data, and Cloud-Resolving Storm Simulator (CReSS). This study mostly focuses on 13 Desember 2016 only. The typical synoptic pattern of lake-effect snowstorm induced easterly in the Yeongdong region. Clouds generated due to high temperature difference between 850 hPa and sea surface (SST) penentrated in the Yeongdong region along with northerly and northeasterly, which eventually resulted precipitation. The cloud base height before the precipitation changed from 750 m to 1,280 m, which was in agreement with that from ceilometer at Sokcho. However, ceilometer tended to detect the cloud base 50 m ~ 100 m below strong signal of lidar backscattering coefficient. As a result, the depolarization ratio increased vertically while the backscattering coefficient decreased about 1,010 m~1,200 m above the ground. Lidar signal might be interpreted to be attenuated with the penetration depth of the cloud layer with of nonspherical hydrometeor (snow, ice cloud). An increase in backscattering signal and a decrease in depolarization ratio occured in the layer of 800 to 1,010 m, probably being associated with an increase in non-spherical particles. There seemed to be a shallow liquid layer with a low depolarization ratio (<0.1) in the layer of 850~900 m. As the altitude increases in the 680 m~850 m, the backscattering coefficient and depolarization ratio increase at the same time. In this range of height, the maximum value (0.6) is displayed. Such a result can be inferred that the nonspherical hydrometeor are distributed by a low density. At this time, the depolarization ratio and the backscattering coefficient did not increase under observed melting layer of 680 m. The lidar has a disadvantage that it is difficult for its beam to penetrate deep into clouds due to attenuation problem. However it is promising to distinguish hydrometeor morphology by utilizing the depolarization ratio and the backscattering coefficient, since its vertical high resolution (2.5 m) enable us to analyze detailed cloud microphysics. It would contribute to understanding cloud microphysics of cold clouds and snowfall when remote sensings including lidar, radar, and in-situ measurements could be timely utilized altogether.

• Journal of Korean Society of Forest Science
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• v.106 no.1
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• pp.63-69
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• 2017

This study aimed to investigate orographic precipitation and green dam (water conservation function) characteristics in a deciduous forest watershed in the region of Mt. Ungseok, Sancheong, Gyeongnam, South Korea. The rainfall and runoff of the watershed were monitored for six years (2011~2016) at the weather station and at the weir of the watershed, respectively. During the study period, the rainfall in the watershed (mountainous area) was larger than that of the meteorological station (flat area) nearest to the watershed. Besides, compared to the normal year (1981~2010), the rainfall has increased and the seasonal distribution of rainfall of the mountainous area has changed. These changes might have been caused by climate change. The runoff ratio was highest in spring, followed by winter, summer and fall, whilst the runoff was highest in summer, followed by spring, fall and winter. This difference seems to be due to the melting of snow in dry spring and intensive rainfall in summer. The total runoff in the watershed was calculated as $10,143.8ton{\cdot}ha{\cdot}yr^{-1}$.

• Journal of Climate Change Research
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• v.4 no.1
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• pp.41-49
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• 2013

Recent findings have revealed that black carbon is one of the substantial materials affecting climate change along with greenhouse gases. Usually, black carbon is generated by incomplete combustion of biomass and deposited on snow and ice surface, resulting in increasing adsorption of radiant energy and accelerating ice melting. However, it is still questionable what the emission characteristics of black carbons from biomass combustion is. We investigated the emission characteristics of black carbon generated from a wood stove in this study. We found that the emission of black carbon was highly dependent upon combustion temperature and the amount of combustion air supplied. The emission factors were 1.01 g-BC/kg-Oak for fireplace wood burning under incomplete combustion, 0.37 g-BC/kg-Oak for fireplace wood burning under complete combustion and 0.29 g-BC/kg-Oak for small wood-stove burning.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.4
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• pp.52-67
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• 2020

Recently, the Arctic has been exposed to snow-covered land due to melting permafrost every year, and the Korea Geographic Information Institute(NGII) provides polar spatial information service by establishing spatial information of the polar region. However, there is a lack of spatial information on vegetation sensitive to climate change. This research used a multi-temporal Sentinel-2 image to perform land cover classification of the Ny-Ålesund in Arctic Svalbard. In the pre-processing step, 10 bands and 6 vegetation spectral index were generated from multi-temporal Sentinel-2 images. In image-classification step is consisted of extracting the vegetation area through 8-class land cover classification and performing the vegetation species classification. The image classification algorithm used Random Forest to evaluate the accuracy and calculate feature importance through Out-Of-Bag(OOB). To identify the advantages of multi- temporary Sentinel-2 for vegetation classification, the overall accuracy was compared according to the number of images stacked and vegetation spectral index. Overall accuracy was 77% when using single-time Sentinel-2 images, but improved to 81% when using multi-time Sentinel-2 images. In addition, the overall accuracy improved to about 83% in learning when the vegetation index was used additionally. The most important spectral variables to distinguish between vegetation classes are located in the Red, Green, and short wave infrared-1(SWIR1). This research can be used as a basic study that optimizes input characteristics in performing the classification of vegetation in the polar regions.

• Journal of the Korean GEO-environmental Society
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• v.25 no.2
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• pp.5-14
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• 2024

Reinforced concrete bridge decks are the first to be damaged by vehicle loads and rain infiltration. Concrete deterioration primarily occurs owing to the corrosion of rebars and other metal components by chlorides used for snow and ice melting. The structural condition and concrete deterioration of the bridge decks within the pavement were evaluated using ground-penetrating radar (GPR) survey data. To evaluate concrete deterioration in bridges, it is necessary to develop GPR data analysis techniques to accurately identify deteriorated locations and rebar positions. GPR exploration involves the acquisition of reflection and diffraction wave signals due to differences in radar wave propagation velocity in geotechnical media. Therefore, a full-waveform inversion (FWI) method was developed to evaluate the deterioration of reinforced concrete bridge decks by estimating the radar wave propagation velocity in geotechnical media using GPR data. Numerical experiments using a GPR velocity model confirmed the deterioration phenomena of bridge decks, such as concrete delamination and rebar corrosion, verifying the applicability of the developed technology. Moreover, using the synthetic GPR data, FWI facilitates the determination of rebar positions and concrete deterioration locations using inverted velocity images.