• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.151-151
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• 2018

The present study is aimed to quantifying the uncertainty in the general circulation model (GCM) selection and its impacts on hydrology studies in the basins. For this reason, 13 GCMs was selected among the 26 GCM models of the Fifth Assessment Report (AR5) scenarios. Then, the climate data and hydrologic data with two Representative Concentration Pathways (RCPs) of the best model (INMCM4) and worst model (HadGEM2-AO) were compared to understand the uncertainty associated with GCM models. In order to project the runoff, the Precipitation-Runoff Modelling System (PRMS) was driven to simulate daily river discharge by using daily precipitation, maximum and minimum temperature as inputs of this model. For simulating the discharge, the model has been calibrated and validated for daily data. Root mean square error (RMSE) and Nash-Sutcliffe Efficiency (NSE) were applied as evaluation criteria. Then parameters of the model were applied for the periods 2011-2040, and 2070-2099 to project the future discharge the five large basins of South Korea. Then, uncertainty caused by projected temperature, precipitation and runoff changes were compared in seasonal and annual time scale for two future periods and RCPs compared to the reference period (1976-2005). The findings of this study indicated that more caution will be needed for selecting the GCMs and using the results of the climate change analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.107-107
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• 2018

기후 변화가 심해짐에 따라 한반도의 기후 또한 온대에서 아열대로 변화하고 있다. 기후대가 변하게 되면 수문학적 순환 및 식생의 분포 또한 달라지게 된다. 식생의 분포는 결국 토지 이용을 의미하며, 서로 다른 토지 이용은 대기와의 상호작용을 통해 각기 다른 반응을 보이게 된다. 본 연구에서는 기후대가 가장 빠르게 변화하고 있는 제주도를 대상으로 기후 변화 및 토지 이용 변화에 따른 생태수문학적 영향을 Ecosystem Demography Model version 2.2(ED-2.2) 모형을 사용하여 살펴 본다. 제주도의 플럭스 타워 및 산림 조사 자료를 활용하여 ED-2.2 모형을 검증하였다. CRU-NCEP 기상자료 및 Land-Use Harmonization (LUH) 토지이용자료를 활용하여 과거기간(1500~2015)의 잠재 식생 및 실제 식생 상태를 산정하고 그 차이를 분석하였다. 산정된 최종 실제 식생 상태를 바탕으로 기후 및 토지이용 시나리오(RCP 3.0 및 6.0)를 적용하고, 다양한 전지구모형(GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, MIROC5)의 기상자료에 따라 물 순환, 탄소 순환 및 식생의 분포가 어떻게 달라지는 지 분석한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.457-457
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• 2017

최근 기후변화에 따른 수문환경의 변화로 인해 도시지역에 침수피해가 빈번히 발생하고 있으며, 이는 도시화로 인한 인구밀도 증가 및 불투수율이 높아짐으로써 땅속으로 스며들지 못한 빗물이 지표면으로 유출되어 침수피해로 나타나고 있다. 또한, 복잡한 하수관망의 정비와 관리가 어렵다는 점이 침수를 유발하는 원인이 되기도 한다. 강남역과 울산 태화강 침수 피해를 대표적인 예로 들 수 있다. 강남역 일대는 대한민국의 대표적인 상업의 중심지라고 할 수 있으며, 2010년부터 3년간 내수침수가 발생하여 사회적인 이슈가 되었으며, 2016년 울산 및 제주도에서는 제 18호 태풍 차바(CHABA)의 한반도 상륙으로 하천이 범람하고 내수침수가 발생하여 많은 재산 피해를 입혔다. 이처럼 기후변화로 인한 태풍 발생 빈도 증가 및 국지성 호우는 도시지역에 많은 침수피해를 발생시키기 때문에 정확한 침수분석과 취약성 평가를 실시해야 한다. 따라서 본 연구에서는 서울시 강남역 일대를 대상으로 강우-유출모형을 구축하였으며, 기상청에서 제공하는 HadGEM3-RA(12.5km격자자료)를 이용하여 미래 기후변화에 따른 불확실성을 고려한 취약성 평가하였다. 이는 상습침수지역에 대한 근본적인 침수원인을 파악하고 사전에 예방할 수 있는 객관적 평가자료로 활용가능할 것으로 기대된다.

• Journal of Climate Change Research
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• v.7 no.4
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• pp.407-419
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• 2016

The low flow is the necessary and important index to establish national water planning, however there are lots of uncertainty in the low flow estimation. Therefore, the objectives of this study are to assess the climate change uncertainty and the effects of hydrological models on low flow estimation. The 5 RCMs (HadGEM3-RA, RegCM4, MM5, WRF, and RSM), 5 statistical post-processing methods and 2 hydrological models were applied for evaluation. The study area were selected as Chungju dam and Soyang river dam basin, and the 30 days minimum flow is used for the low flow evaluation. The results of the uncertainty analysis showed that the hydrological model was the largest source of uncertainty about 41.5% in the low flow projection. The uncertainty of hydrological model is higher than the other steps (RCM, statistical post-processing). Also, VIC model is more sensitive for climate change compared to SWAT model. Therefore, the hydrological model should be thoroughly reviewed for the climate change impact assessment on low flow.

• Journal of Climate Change Research
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• v.8 no.3
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• pp.187-199
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• 2017

We attempted to assess the impact of climate change on rice yields in Cambodia and to investigate adaptation strategies to climate change including more drastically shifting the planting dates and considering more fertilizer application levels. The potential yields of two wet season rice cultivars (Sen Pidao and Phka Rumduol) under two climate change scenarios in Cambodia were simulated using the CERES-Rice model. Field experiments conducted at the Cambodian Agricultural Research and Development Institute (CARDI), in 2010, 2011, and 2013 and climate variables from the HadGEM3-RA model were collected for this study. Compared with the baseline (1991-2000), yields of Sen Pidao rice will decrease under climate change and yields of Phka Rumduol rice could increase or decrease depending on fertilizer rates and the periods (2040s, 2050s, and 2080s). In general, the variations in the simulated effects of climate change on yields were more sensitive at fertilizer N100-N200 and less sensitive at fertilizer N0-N50. It is likely that forward shifts of planting date from the baseline plating date for the two cultivars in the future can be more benefitted than backward shifts. It is concluded that the CERES-Rice model can be useful to provide efficacious adaptation strategies in Cambodia.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.168-168
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• 2018

최근 기후변화로 인하여 전 세계적으로 과거 강우사상에서 확인되지 않는 극치사상이 빈번하게 관측되고 있으며 이에 따른 피해도 증가하고 있다. 미래의 기상학적 변동성 및 기후변화 영향은 지구순환모형 (General Circulation Models, GCM)을 통해 구체화되며 가장 일반적인 기후변화 전망자료로서 활용된다. 그러나 산정된 기후변화 시나리오마다 서로 그 특성에 차이가 있으며 이러한 이유로 다양한 원인으로 인해 큰 변동성을 가지는 미래 극치강우를 하나의 시나리오로 분석하기에는 무리가 있다. 또한 다양한 시나리오를 통해 분석한 결과값이 상이하며 이러한 시나리오별 산정 결과의 차이는 사용자에게 혼란을 야기할 수 있어 이를 하나의 결과로 나타낼 필요성이 있으나 정량적인 대푯값을 얻기 위해 특정 시나리오를 선택하는 것은 신뢰성에 문제가 있다. 본 연구에서는 시나리오들을 정량적 지표에 의거하여 혼합된 하나의 시나리오로 표출하고자 하였다. CORDEX-RCMs 시나리오 중 HadGEM3-RA, RegCM, SNU_WRF 및 GRIMs를 입력 자료로 하여 다중모형앙상블(Multi-Model Ensemble, MME)을 통해 낙동강 유역의 극치강우에 대한 하나의 최적 기후변화 시나리오를 도출하고자 하였으며 계층적 베이지안 (Hierarchical Bayesian Model, HBM) 기법을 통하여 기후변화 시나리오에 내제된 불확실성에 대한 정량적인 해석을 수행하였다.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.34-45
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• 2018

The cleat system in coalbed methane (CBM) reservoirs is generally occupied by water which liberated during the coalification process, and behavior of water have influence on CBM production performance. Therefore, it is essential to investigate the effect of the water saturation to operate the degasification process and predict the CBM production performance properly. In this study, type curve analyses were performed on CBM reservoirs under various water saturation to improve the prediction of production performance. A CBM reservoir models with fully-, modestly-, and undersaturated reservoir were built to get production data using GEM by CMG Ltd., and the data were matched with Fetkovich, Palacio-Blasingame(P-B), and Agarwal-Gardner (A-G) type curve. The results showed that undersaturated reservoir was successfully matched by A-G type curve, while the Fetkovich type curve was inappropriate for matching in the late time. The modestly saturated model could be almost corresponded with all the type curve methods at late production period. For the fully saturated model, after peak production had been reached, both P-B and A-G methods showed a proper match to the reservoir production data without long-term production period. Based on the results, merit and demerit of each type curve under specific water saturation were analyzed and listed. Therefore, it is believed that the production data analysis with proper type curve model considering water saturation can be performed to predict accurate production performance.

• Journal of the Mineralogical Society of Korea
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• v.20 no.2 s.52
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• pp.97-102
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• 2007

NMR experiments with various pulse repetition delay time were carried out for the $^{15}N\;and\;^{13}C$ of a natural gem diamond and synthetic diamonds. The natural gem diamond had a weak $^{13}C$ peak at 34.1ppm when 30 second pulse repetition delay time was applied. Similar but more prominent $^{13}C$ peaks were observed at 34.2 ppm with 0.5 second pulse repetition delay time and at 34.7 ppm with 50 second pulse repetition delay time for the synthetic diamonds. Any meaningful $^{15}N$ peak was not observed for either natural or synthetic diamonds due to extremely low content of the $^{15}N$. Significant relationship was observed between relative spin-lattice relaxation times we estimated and the content of impurities. however, it was not possible to distinguish natural diamond from synthetic diamonds due to very similar characteristics of their $^{13}C$ NMR signals except relative spin-lattice relaxation times.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.151-159
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• 2010

The effect of calcite and gypsum on the hydration of Portland cement was investigated using GEM-PSI, a geochemical model. Addition of calcite and gypsum up to 5 wt% of total cement clinker into Portland cement was found to influence the hydrate assemblage of the hydrated cement in different ways. The results of geochemical modelling showed that the fraction of calcium monocarbonate increased by the hydration of cement with the increase of calcite addition. The results of modelling also indicated that gypsum increased the fraction of ettringite in the assemblage of hydrated cement as the amount of gypsum added increases. This study showed that porosity generated by the hydration of cement had a significant relation with the amount of calcite and gypsum added. The porosity of hydrated cement was lower when calcite added up to 3 wt% of cement clinker compared to the hydrated cement with the same amount of gypsum addition. However, when calcite added more than 3% of cement clinker, the porosity of hydrated cement were higher than that of hydrated cement with the same amount of gypsum addition.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.77-80
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• 2004

For the development of the alternative control system against the major forest pests, Beauveria spp. F-101, isolated from a dead larva of Thecodiplosis japonensis, was selected because this isolate showed high pathogenicities against T. japonensis and Acantholyda parki. Beauveria spp. F-101 had irregular clustered conidio-phores and conidia borne on a distinctive apical zigzag extension, and it showed typical characteristic of the genus, Beauveria in morphology. For molecular based-identification, the ribosomal ITS region of Beauveria spp. F-101 was amplified with ITS1 and ITS4 primers, and cloned into pGEM- T Easy vector. The amplified PCR product was 569 bp in size and completely sequenced. The similarities of the cloned ITS sequence were 99 ％ and 97％ to those of B. bassiana and B. brongniartii, respectively. In comparison to other species among the genus Beauveria, the ITS region of Beauveria spp. F-101 showed a similarity of 95％ to B. amorpha, 95％ to B. tenella, 89％ to B. vermiconia and 69％ to B. alba, respectively. In addition, in comparison to different genus, it had 95％ similarities to Cordyceps militaris and 91％ to Paecilomyces tenuipes. Accordingly, the current result suggests that Beauveria spp. F-101 was a variant of B. bassiana and it seems to be a new isolate considering sequence variation in ITS region.