• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.36-36
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• 2014

Apple blotch, caused by Marssonina coronaria, induce early defoliation in apple and leading to critical economic losses in apple orchards in Korea. Since M. coronaria is difficult to culture, we developed isolation and cultural method. We collected M. coronaria isolates from Gyeongbuk Province and then constructed phylogentic tree based on ITS regions. As the results, phylogenetic relationship indicated that all Korean isolates formed a same cluster and closely related to Chinese isolates [1]. Ecological characteristic of M. coronaria have been observed in apple orchards which located in Gyeongbuk Province from 2011 to present. As the results, the typical apple blotch symptoms were observed from July, and then the infected leaves were discolored and formed acervuli on the leaves. After rainfall, severe infection of symptoms such as discoloration and early defoliation were continuously observed until October. Also overwintered conidia were observed in next March on the fallen diseased leaves [2]. In the last 5 years, ascopores of M. coronaria were not observed in apple orchards which were severely infected by M. coronaria in Korea. Thus, it is assumed that overwintered conidia could be a primary inoculum of M. coronaria. Meanwhile, apple blotch has long latent periods compare to other apple disease. During the latent period, early diagnosis of apple blotch is the most important to control the disease by spray fungicide. In this reason, we developed novel diagnostic method to detect M. coronaria during latent period using optical coherence tomography (OCT) and Loop-mediated isothermal amplification (LAMP) method [2, 3]. In this presentation, it will introduce ecological characterization of M. coronaria in Korea and unique detection technique of M. coronaria in apple. It will be helpful to develop new strategies to control apple blotch in Korea.

• Journal of Korea Water Resources Association
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• v.41 no.12
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• pp.1199-1210
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• 2008

The mean residence time is the time scale for intermediate status between infiltration and runoff and one of the critical factors for understanding runoff response, erosion, and eco-hydrological processes. This research explored a direct method to estimate the mean residence time over existing indirect, isotope tracer method. Spatial and temporal distributions of soil moisture have been monitored for a year with 2-hours monitoring interval. Mean residence time for soil moisture showed apparent increasing tendency to deeper depth and decreasing trend during summer periods, which had intensive rainfall events. The mean residence times obtained from this research showed similar trend to those obtained from other isotope methods, which means the direct method can be an efficient approach to obtain the mean residence time.

• Journal of Korea Water Resources Association
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• v.53 no.3
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• pp.215-223
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• 2020

The objective of this study is to develop a prediction model of specific degradation using data mining classification especially for the rivers in South Korea river. A number of critical predictors such as erosion and sediment transport were extracted for the prediction model considering watershed morphometric characteristics, rainfall, land cover, land use, and bed material. The suggested model includes the elevations at the mid relative area of the hypsometric curve of watershed morphomeric characteristics, the urbanization ratio, and the wetland and water ratio of land cover factors as the condition factors. The proposed model describes well the measured specific degradation of the rivers in South Korea. In addition, the development model was compared with the existing models, since the existing models based on different conditions and purposes show low predictability, they have a limit about the application of Korean River. Therefore, this study is focusing on improving the applicability of the existing model

• Journal of the Korean Geotechnical Society
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• v.32 no.5
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• pp.37-48
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• 2016

This study aims to figure out the behavior of runoff and drainage of pervious sidewalk block in actual construction environment by experiments. The specimens with surface layer and bedding layer are subjected to the drainage test by considering unsaturated condition and unique rainfall condition in urban areas. The repeated drainage test and clogging test were conducted with time intervals, and 3D X-ray CT image analysis and evaporation test were carried out for a quantitative analysis of drainage test. The results present that the spatial distribution of pores by evaporation for time intervals induces runoff. Especially, the bedding layer under the block is significantly critical in overall hydraulic behavior such as drainage and evaporation compared to the surface layer. Moreover, the sediments in pores promote the change in pores by evaporation and this induces deteriorated drainage capacity which is hard to recover. In addition, it is revealed that the maximum runoff height grows as the drainage capacity declines depending on the pre-wetting condition.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.188-188
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• 2016

The Mekong which is one of the world's most significant rivers plays an extremely important role to South East Asia. Lying across six riparian countries including China, Myanmar, Thailand, Laos, Cambodia and Vietnam and being a greatly biological and ecological diversity of fishes, the river supports a huge population who living along Mekong Basin River. Therefore, much attention has been focused on the giant Mekong Basin River, particularly, the soil erosion and sedimentation problems which rise critical impacts on irrigation, agriculture, navigation, fisheries and aquatic ecosystem. In fact, there have been many methods to calculate these problems; however, in the case of Mekong, the available data have significant limitations because of large area (about 795 00 km2) and a failure by management agencies to analyze and publish of developing countries in Mekong Basin River. As a result, the Universal Soil Loss Equation (USLE) model in a GIS (Geographic Information System) framework was applied in this study. The USLE factors contain the rainfall erosivity, soil erodibility, slope length, steepness, crop management and conservation practices which are represented by raster layers in GIS environment. In the final step, these factors were multiplied together to estimate the soil erosion rate in the study area by using spatial analyst tool in the ArcGIS 10.2 software. The spatial distribution of soil loss result will be used to support river basin management to find the subtainable management practices by showing the position and amount of soil erosion and sediment load in the dangerous areas during the selected 56- year period from 1952 to 2007.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.5
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• pp.1-11
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• 2021

Soil moisture plays a critical role in hydrological processes, land-atmosphere interactions and climate variability. It can limit vegetation growth as well as infiltration of rainfall and therefore very important for agriculture sector and food protection. Recently, due to the increased damage from drought caused by climate change, there is a frequent occurrence of shortage of agricultural water, making it difficult to supply and manage stable agricultural water. Efficient water management is necessary to reduce drought damage, and soil moisture management is important in case of upland crops. In this study, soil moisture was calculated based on the water balance model, and the suitability of soil moisture data was verified through the application. The regional soil moisture was calculated based on the meteorological data collected by the meteorological station, and applied the Runs theory. We analyzed the spatiotemporal variability of soil moisture and drought impacts, and analyzed the correlation between actual drought impacts and drought damage through correlation analysis of Standardized Precipitation Index (SPI). The soil moisture steadily decreased and increased until the rainy season, while the drought size steadily increased and decreased until the rainy season. The regional magnitude of the drought was large in Gyeonggi-do and Gyeongsang-do, and in winter, severe drought occurred in areas of Gangwon-do. As a result of comparative analysis with actual drought events, it was confirmed that there is a high correlation with SPI by each time scale drought events with a correlation coefficient.

• The Journal of Fisheries Business Administration
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• v.52 no.2
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• pp.55-67
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• 2021

Global warming affects critical natural resources, one of which is the oceans that occupy 70% of the total cover of the earth. In other words, ocean warming is a subset of global warming which needs to be addressed urgently. Purple laver (pyropia spp.) is one of the most vulnerable items to climate change although it is a major export product of Korean fisheries. The purpose of this study is to analyze the causality of how climate change caused by global warming affects the increase or decrease of PLP (purple laver production). The target area for analysis was set to Maro-hae between Jindo-gun and Haenam-gun. We selected marine environmental factors and meteorologic factors that could affect PLP as variables, as well as co-integration tests to determine long-term balance, and the Granger causticity tests. As a result, PLP and marine environmental factors WT (water temperature), pH, and DO confirmed that long-term equilibrium relationships were established, respectively. However, there is only causality with WT and it is confirmed that there is only a correlation between pH and DO (dissolved oxygen). There was no long-term equilibrium relationship between PLP and HDD (heating degree days) and there is a causal effect that HDD affects PLP; however, it was less clear than that of WT. The relationship between PLP and RF (rainfall), WS (wind speed), SS (percentage of sunshine), and FF (farm facilities) was all balanced in the long term, and causality exists. Based on the results of the analysis, policy proposals were made.

• The Journal of Engineering Geology
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• v.33 no.3
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• pp.489-502
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• 2023

Urban floods pose significant challenges to cities worldwide, driven by the interplay between urbanization and climate change. This review examines recent studies of urban floods to understand their causes, impacts, and potential mitigation strategies. Urbanization, with its increase in impermeable surfaces and altered drainage patterns, disrupts natural water flow, exacerbating surface runoff during intense rainfall events. The impacts of urban floods are far-reaching, affecting lives, infrastructure, the economy, and the environment. Loss of life, property damage, disruptions to critical services, and environmental consequences underscore the urgency of effective urban flood management. To mitigate urban floods, integrated flood management strategies are crucial. Sustainable urban planning, green infrastructure, and improved drainage systems play pivotal roles in reducing flood vulnerabilities. Early warning systems, emergency response planning, and community engagement are essential components of flood preparedness and resilience. Looking to the future, climate change projections indicate increased flood risks, necessitating resilience and adaptation measures. Advances in research, data collection, and modeling techniques will enable more accurate flood predictions, thus guiding decision-making. In conclusion, urban flooding demands urgent attention and comprehensive strategies to protect lives, infrastructure, and the economy.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.232-232
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• 2022

1차원 관망해석모형과 2차원 지표면범람 해석모형을 이용한 도시지역의 실시간 홍수예·경보시스템 구축은 모형의 모의에 많은 시간이 소요되므로 한계가 있다. 또한, 연구유역에서 시나리오 강우에 대해 침수를 유발시키는 한계강우량을 1-2차원 모형의 시행착오법을 적용한 반복적인 수행을 통해 산정하는 것은 비효율적인 방법이다. 따라서, 본 연구에서는 이에 대한 해결책으로 로지스틱 회귀를 이용하여 배수분구별 침수 발생기준 강우량을 산정하고자 한다. 침수 발생 한계강우량 산정을 배수분구 단위로 제시하기 위하여 로지스틱 회귀분석을 이용하였다. 풍수해저감종합계획(2015)과 침수흔적도를 이용하여 배수분구 별 침수이력에 대한 데이터베이스를 구축하고, 이를 1-2차원 수리해석을 통한 침수심과 함께 로지스틱 회귀모형에 학습하였다. 지속시간 1시간, 10mm 강우부터 500년 빈도의 Huff 3분위 시나리오 17개를 사용하여 확률강우량을 산정하였고, 이를 1-2차원 수리해석을 위한 입력자료로 사용하였다. EPA-SWMM을 통한 1차원 도시유출해석과 FLO-2D를 통한 2차원 침수해석에서 20cm 이상의 침수심이 발생하거나 지상관측자료, 침수흔적도 및 풍수해저감종합계획에서 실제 침수가 발생했을 경우를 1, 그렇지 않은 경우를 0으로 하여 데이터베이스를 구축하여 로지스틱 회귀모형에 학습시켜 침수 발생 한계강우량을 산정하였다. 로지스틱 회귀분석을 통해 서울시 지역의 배수분구별 한계강우량을 산정할 수 있으며, 지속적으로 관측되는 강우 및 침수 발생 유무 자료를 추가함으로써 산정된 침수 한계강우량을 상회하는 강우 사상이 나타났을 시에 침수 발생 유무를 확인하여 본 연구에서 제안한 방법에 대해 검증이 가능할 것으로 보인다.

• Journal of the Korean Geotechnical Society
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• v.30 no.4
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• pp.35-45
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• 2014

Limit equilibrium methods of slope stability analysis have been widely adopted mainly due to their simplicity and applicability. However, the conventional methods may not give reliable and convincing results for various geological conditions such as nonhomogeneous and anisotropic soils. Also, they do not take into account soil slope history nor the initial state of stress, for example excavation or fill placement. In contrast to the limit equilibrium analysis, the analysis of deformation and stress distribution by finite element method can deal with the complex loading sequence and the growth of inelastic zone with time. This paper proposes a technique to determine the critical slip surface as well as to calculate the factor of safety for shallow failure on partially saturated soil slope. Based on the effective stress field in finite element analysis, all stresses are estimated at each Gaussian point of elements. The search strategy for a noncircular critical slip surface along weak points is appropriate for rainfall-induced shallow slope failure. The change of unit weight by seepage force has an effect on the horizontal and vertical displacements on the soil slope. The Drucker-Prager failure criterion was adopted for stress-strain relation to calculate coupling hydraulic and mechanical behavior of the partially saturated soil slope.