• Korean Journal of Environmental Agriculture
• /
• v.27 no.4
• /
• pp.314-320
• /
• 2008

During the summer season, more than half of the annual precipitation in Korea occurs during the summer season due to the geographical location in the Asian monsoon belt. So, this causes severe soil erosion from croplands, which is directly linked to the deterioration of crop/land productivity and surface water quality. Therefore, much attention has been given to develop accurate estimation tools of soil erosion. The aim of this study is to assess the performance of using the empirical Universal Soil Loss Equation (USLE) and the physical-based model of the Water Erosion Prediction Project (WEPP) to quantify eroded amount of soil from agricultural fields. Input data files, including climate, soil, slope, and cropping management, were modified to fit into Korean conditions. Chuncheon (forest) and Jeonju (level-plain) were selected as two Korean cities with different topographic characteristics for model analysis. The results of this current study indicated that better soil erosion prediction can be achieved using the WEPP model since it has better power to illustrate a higher degree of spatial variability than USLE in topography, precipitation, soils, and crop management practices. These present findings are expected to contribute to the development of the environmental assessment program as well as the conservation of the agricultural environment in Korea.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.203-203
• /
• 2018

기후변화로 인한 몬순 강수량 변동은 세계에서 가장 인구가 많은 몬순 지역의 농업, 수자원, 에너지, 경제 및 사회와 밀접한 관련이 있으므로, 미래의 몬순 강수량 변화를 예측하는 것은 매우 중요하다. 결합 모델 상호 비교 프로젝트의 5 단계(CMIP5)에서는 복사 강제력이 2100년 이후에 약 2.6, 4.5, 6.0 및 $8.5Wm^{-2}$의 증가로 안정화된다고 가정하는 4가지의 다양한 시나리오(RCP 2.6, 4.5, 6.0, 8.5) 자료를 제공하고 있다. 본 연구에서는 한반도의 강수량에 큰 영향을 미치는 동아시아 여름 몬순의 기후 변화에 대해 더욱 집중하고자 한다. CMIP5 모형 자료에 대하여 대표 GCM 모형 선정을 하기 위해, 수문 분야에서 활용 가능한 기후모델 성능 평가 matrix를 구축하였다. 본 연구에서 사용된 평가 matrix는 동아시아 및 한반도 지역을 대상으로 CMIP5 모형의 강수 및 최고?최저기온에 대한 평균 기후장(spatial climatology)과 연변동성(interannual variability)의 모사력을 각 모형별, 계절별 비교뿐만 아니라 극한기후 모사력도 함께 고려하여, 대표 GCM을 선정하였다. 기후변화에 따른 동아시아 지역의 몬순 특성을 더욱 자세히 살펴보기 위해, 대표 GCM으로 선정된 모형들의 2가지 시나리오(RCP4.5와 RCP.5)에 대해 동아시아 지역에서의 여름 몬순 강수 변동 및 특성을 분석 및 비교하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2023.11a
• /
• pp.46-47
• /
• 2023

겨울철에 동아시아는 시베리아 대륙으로부터 부는 북서계절풍의 영향을 크게 받는다. 지속성이 강한 계절풍은 선박의 안전운항과 기상재해에 큰 영향을 미친다. 이 연구에서는 30년간(1992-2021년)의 장기간의 데이터를 이용하여 동아시아에 위치해 있는 우리나라와 일본에서의 겨울철 계절풍의 변화를 분석하였다. 분석한 결과는 다음과 같다. 우리나라 서해안에 위치한 군산에서의 풍속은 시간의 흐름과 함께 약해지는 경향을 보이나, 인천에서는 큰 변화가 보이지 않는다. 우리나라 제주도에 위치한 고산은 다른 두 지역보다 월등히 강한 풍속을 보이나, 이 지역 또한 시간의 흐름과 함께 풍속이 약해지고 있음을 확인하였다. 인천, 군산 및 고산 중에서 풍속이 가장 강한 곳은 고산이고, 그 다음은 인천, 군산의 순이다. 일본의 아키타, 와지마, 하마다의 겨울철 풍속은 세 지역 모두 점진적으로 약해지고 있으나, 2000년에 세 곳 모두 풍속이 급격히 강해진 특징을 보였으며 2005-2007년에는 풍속이 다시 약해졌다. 풍속이 가장 강한 곳은 아키타이며, 그 다음으로는 하마다, 와지마 순이다. 우리나라와 일본을 비교하였을 때, 고산을 제외하고는 일본이 우리나라보다 평균적으로 풍속이 더 강한 양상을 띠고 있어, 서해보다 동해에서 계절풍이 더 강하게 불고 있음을 확인하였다.

• Asian-Australasian Journal of Animal Sciences
• /
• v.9 no.1
• /
• pp.91-99
• /
• 1996

About 7.7 million tons of straw dry matter are being rotten during the monsoon. The objective of this trial was to develop a technique to preserve straw under wet condition. To simulate the moisture content of wet straw, a dry straw was deeped overnight in water. After draining the excess water, the wet straw(668 g moisture $kg^{-1}$) was divided into twenty fractions and preserved with 0, 30, 50 ro 70 g urea $kg^{-1}$ dry matter for either of 30, 60, 90, 120 or 180 days in sealed plastic container. Considering the colour, smell, fungal infestation and pH, the wert straw was preserved excellently up to 180 days when 50 or 70 g of urea per kg DM was used. Urea preservation increased the crude protein contents of straw by 3.6 to 6.4 times (174 to $364g{\cdot}kg^{-1}$) over that of the dry straw ($48g{\cdot}kg^{-1}$). Although the NDF content of straw was not effected by the level of urea or by the length of the preservation period, but the ADF content increased (p > 0.05) by 0.086 to $0.889g{\cdot}kg^{-1}$ straw DM for each g increase in the urea level. At 48 hours, the DM degradability of dry straw was $350g{\cdot}kg^{-1}$, which increased to $633g{\cdot}kg^{-1}$ when preserved with 50 g urea $kg^{-1}$ for 180 days. For the same straw, both the rate(0.0388 vs. 0.0136 fraction $h^{-1}$), the extent(717 vs. $631g{\cdot}kg^{-1}$) of straw degradation and the estimated ME(9.55 vs. $6.51MJ{\cdot}kg^{-1}$ straw DM) were higher in the preserved than the dry straw.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.5
• /
• pp.633-636
• /
• 2002

Six adult Garole rams maintained under a semi-intensive system were used as semen donors for this study. Semen was collectied daily during the monsoon season with the help of an artificial vagina and examined for its quality characteristics. Ejaculates of thick consistency, rapid wave motion, ${\geq}80%$ motility and intense movement of motile spermatozoa were diluted at the rate of 1:1 with egg yolk McIllvaine glucose diluent at $30^{\circ}C$ in water bath. Estrus in ewes was detected by parading aproned rams of proven vigour at 12 h intervals. The ewes (54 Malpura and 23 Avikalin) in estrus were artificially inseminated with fresh diluted ram semen. The overall conception rate was 94.8%, (range 91.7 to 100%). The overall lambing percent was 80.5 with a range of 75.0 to 84.6%. There was no significant (p>0.05) difference in lambing and conception rate because of individual rams. Fertility was significantly lower (p<0.05) in ewes of less than two years and more than six years of age. Breed (Malpura and Avikalin) effect was not observed in conception and lambing rate (p>0.05). No significant difference (p>0.05) in birth weight and 12 month weight was observed between Garole${\times}$Avikalin and Garole${\times}$Malpura crossbred lambs but there was significant (p<0.05) difference at three month and six months body weight of both the crossbred lambs.

• Journal of the Korean association of regional geographers
• /
• v.17 no.5
• /
• pp.521-535
• /
• 2011

This study intended to explain the relationship between climate change and magnetic susceptibility of estuarine sediment. Data of OSL dating and magnetic susceptibility from estuarine tidal sediment were compared with various climate change data. During the last Holocene, the intense of magnetic susceptibility related with weaker Siberian High and stronger Asian Summer Monsoon. It is explained that high precipitation and runoff made much fluvial sediment input to the estuary. From the early to mid Holocene, there is no clear relationship between climate change and MS because of the much coastal sediment input caused by rapid sea level rise and the formation of upland soil and coastal marsh. These results contribute to reconstruct paleo-environmental changes of west coast of Korea, in the way of using benefit of ubiquitous estuarine tidal flats and relatively useful magnetic susceptibility methodoloy.

• Journal of Korean Society on Water Environment
• /
• v.28 no.4
• /
• pp.561-573
• /
• 2012

The object of this study was to analyze long-term water quality gradients during 1992-2008 at six sites of Geumho River and near-by two sites of Nakdong River and their influences on fish trophic guilds and tolerance guilds along with ecological health. Water quality including biological oxygen demand (BOD), chemical oxygen demand (COD), conductivity, total phosphorus (TP), total nitrogen (TN), and total suspended solids (TSS) varied largely depending on the sampling locations and seasons. Values of ambient BOD, COD, TP, and TN were greater in the downstream than in the upstream reach, and seasonal and interannual variabilities were also higher in the downstreams. This phenomenon was evident due to a dilution by the Asian monsoon rainfall during the monsoon. These outcomes indicate that point sources near the downstream are important for the chemical conditions, but also seasonal stream runoff was considered as an important factor regulating the chemical conditions. Conductivity decreased rapidly during the summer due to ionic dilution, and nutrients (N, P), BOD, COD had an inverse function of seasonal precipitation. Based on the water quality, we selected two sites (control site = $C_s$ vs. impacted site = $I_s$) for impact analysis of water chemistry on fish community and trophic/tolerant guilds. Fish guild analysis showed that species diversity was higher in the headwater stream ($C_s$) than the impacted downstream ($I_s$), and that the proportion of tolerant and omnivore species were greater in the impacted site of downstream. Comparisons of water quality between Geumho River and Nakdong River indicated that Geumho River was considered as a point source which degradated water quality to the Nakdong River. Overall, chemical water quality and fish guild analysis suggest that even if current chemical quality got better after 1996 due to continuous constructions of wastewater disposal plants near the downstreams, fish compositions of tolerant and omnivores were still dominated the community. Thus, biological restoration based on ecological health is required for the ecosystem conservation.

• Asian Journal of Atmospheric Environment
• /
• v.6 no.3
• /
• pp.234-243
• /
• 2012

The wintertime high loading for atmospheric pollutants is certainly expected in the Byunsan Peninsula of Korea because of a great-scale reclamation project having construction of 33 km tidal sea dike impounding an area of over 40,000 ha and long-range transport. The goal of this study is to trace the origin of this wintertime burden for ambient particulate matter (hereafter called "PM") in the Byunsan Peninsula of Korea. The size-segregated (i.e., cutoff size from 0.01 ${\mu}m$ to 4.7 ${\mu}m$) PM sampling was conducted at a ground-based site of Byunsan Peninsula located in the west coast of Korean Peninsula during the height of dike constructing. Data archived in this study are the mass concentrations of ionic, elemental, and carbonic components in size-fractioned PM. The elemental mass of individual submicrometer particles was also analyzed. The sum of 5-source (i.e., elemental carbon, organic materials, inorganic secondary pollutants, crustal matter, and sea-salts) concentrations shows the bimodal distribution (major and minor peaks formed around $D_p$, 0.65 ${\mu}m$ and $D_p$, 4.7 ${\mu}m$, respectively) by border with 0.19 ${\mu}m$ of cutoff size. The concentrations of EC in $PM_{1.1-0.01}$ in winter and spring times were 4.62 ${\mu}g\;m^{-3}$ and 3.74 ${\mu}g\;m^{-3}$, respectively. Elemental masses of submicron individual particles are classified into two groups, i.e., the major elements (Cl, Al, Si, S, and P) and the minor trace elements. Cluster analysis differentiated the elements in submicron individual particles into 4-cluster. Among them, three clusters are in agreement with the major (Al, Si, S, and P), minor (Fe, Ca, and K), and trace compositions of coal burning. Meanwhile, Cl classified as an independent cluster has different source profile which was mainly due to the Saemangeum seawall project. Some highly toxic elements (e.g., Cr, Mn, and As (and/or Pb)) were also detected in some part of submicron individual PM. As a consequence, the combination of the Saemangeum project and winter monsoon played a considerable part in the double aggravation of wintertime air pollution in the Byunsan Peninsular.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.5
• /
• pp.581-588
• /
• 2019

A long-term trend analysis of cold water masses along eastern coast of South Korea was performed during summer, based on wind speed, wind direction, and sea surface temperature (SST) data. Wind data collected over a 22-year period (1997-2011) were compared with another set of data collected over the successive 7-year (2012-2018), highlighting a general decrease in the frequency and speed of south winds. However, both the frequency and speed of these winds have been higher in June between 2012-2018, rather than between 1997-2011. The cold water season between July and August was faster during the 7-year period; moreover, the SSTs registered around Gangneung (EN) rose by $0.5^{\circ}C- 1.8^{\circ}C$, while those around Yeongdeok (EC) and Gijang (ES) increased by only $0.1^{\circ}C-0.3^{\circ}C$. The number of cold water days during the 7-year period, compared to those recorded during previous years (1990-2011, satellite SST data by NOAA/AVHRR), decreased in the proximity of Yeongdeok and Gijang, but increased in the proximity of Kangneung. Additionally, the number of cold water days around Kangneung, Yeongdeok, and Gijang increased in June highlighting a geographical and temporal change in the occurrence of cold waters. These observation can be explained by variations in the pressure distribution that should have weakened the East Asian monsoon, affecting the direction and speed of winds that regulate the flow of cold waters.

• Journal of the Korean earth science society
• /
• v.44 no.1
• /
• pp.1-12
• /
• 2023

Oceanic wind waves have been recognized as one of the important indicators of global warming and climate change. It is necessary to study the spatial and temporal variability of significant wave height (SWH) and wave direction in the Yellow Sea and a part of the East China Sea, which is directly affected by the East Asian monsoon and climate change. In this study, the spatial and temporal variability including seasonal and interannual variability of SWH and wave direction in the Yellow Sea and East China Sea were analyzed using European Center for Medium-Range Weather Forecasts (ECMWF) Reanalysis 5 (ERA5) data. Prior to analyzing the variability of SWH and wave direction using the model reanalysis, the accuracy was verified through comparison with SWH and wave direction measurements from Ieodo Ocean Science Station (I-ORS). The mean SWH ranged from 0.3 to 1.6 m, and was higher in the south than in the north and higher in the center of the Yellow Sea than in the coast. The standard deviation of the SWH also showed a pattern similar to the mean. In the Yellow Sea, SWH and wave direction showed clear seasonal variability. SWH was generally highest in winter and lowest in late spring or early summer. Due to the influence of the monsoon, the wave direction propagated mainly to the south in winter and to the north in summer. The seasonal variability of SWH showed predominant interannual variability with strong variability of annual amplitudes due to the influence of typhoons in summer.