• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.206-215
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• 2015

Predicting the changes in the potential distribution of invasive alien plants under climate change is an important and challenging task for the conservation of biodiversity and management of the ecosystems in streams and reservoirs. This study explored the effects of climate change on the potential future distribution of Paspalum distichum var. indutum in the Korean Peninsula. P. distichum var. indutum is an invasive grass species that has a profound economic and environmental impact in the waterfronts of freshwater ecosystems. The Maxent model was used to estimate the potential distribution of P. distichum var. indutum under current and future climates. A total of nineteen climatic variables of Worldclim 1.4 were used as current climatic data and future climatic data predicted by HadGEM2-AO with both RCP 2.6 and RCP 8.5 scenarios for 2050. The predicted current distribution of P. distichum var. indutum was almost matched with actual positioning data. Major environmental variables contributing to the potential distribution were precipitation of the warmest quarter, annual mean temperature and mean temperature of the coldest quarter. Our prediction results for 2050 showed an overall reduction in climatic suitability for P. distichum var. indutum in the current distribution area and its expansion to further inland and in a northerly direction. The predictive model used in this study appeared to be powerful for understanding the potential distribution, exploring the effects of climate change on the habitat changes and providing the effective management of the risk of biological invasion by alien plants.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.115-124
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• 2018

Resilience has been widely used in various fields including design and operation of infrastructures. The resilient infrastructures not only reduce the damage scale of various disasters but also reduce the time and cost required for restoration. However, resilience rarely applied to promote efficient management of agricultural infrastructures. Recently, drought is an aggravating disaster by climate change and need countermeasures. Therefore, we tried to demonstrate evaluating measures in case of drought under consideration of resilience. This study applied the robustness-cost index (RCI) to evaluate alternative solution of the supply problem of a large agricultural reservoir under drought conditions. Four structural alternatives were selected to estimate the robustness index (RI) and the cost index (CI) to obtain the RCI values. Structural alternatives are classified into temporary measures and permanent measures. Temporary measures include the development of a tube wells and the installation of the portable pump, while the permanent measures include the installation of a pumping stations and the pumping water to the reservoir (Yeongsan River-Naju reservoir). RCI values were higher in permanent measures than those of temporary measures. Initial storage of the reservoir also affected RCI values of the drought measures. Permanent measures installation and management of early stage of the reservoir storage shortage was identified as the most resilient system.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.68-76
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• 2006

A thermal time-based two-step phenological model was used to project flowering dates of Japanese cherry in South Korea from 1941 to 2100. The model consists of two sequential periods: the rest period described by chilling requirement and the forcing period described by heating requirement. Daily maximum and minimum temperature are used to calculate daily chill units until a pre-determined chilling requirement for rest release is met. After the projected rest release date, daily heat units (growing degree days) are accumulated until a pre-determined heating requirement for flowering is achieved. Model calculations using daily temperature data at 18 synoptic stations during 1955-2004 were compared with the observed blooming dates and resulted in 3.9 days mean absolute error, 5.1 days root mean squared error, and a correlation coefficient of 0.86. Considering that the phonology observation has never been fully standardized in Korea, this result seems reasonable. Gridded data sets of daily maximum and minimum temperature with a 270 m grid spacing were prepared for the climatological years 1941-1970 and 1971-2000 from observations at 56 synoptic stations by using a spatial interpolation scheme for correcting urban heat island effect as well as elevation effect. A 25km-resolution temperature data set covering the Korean Peninsula, prepared by the Meteorological Research Institute of Korea Meteorological Administration under the condition of Inter-governmental Panel on Climate Change-Special Report on Emission Scenarios A2, was converted to 270 m gridded data for the climatological years 2011-2040, 2041-2070 and 2071-2100. The model was run by the gridded daily maximum and minimum temperature data sets, each representing a climatological normal year for 1941-1970, 1971-2000, 2011-2040, 2041-2070, and 2071-2100. According to the model calculation, the spatially averaged flowering date for the 1971-2000 normal is shorter than that for 1941-1970 by 5.2 days. Compared with the current normal (1971-2000), flowering of Japanese cherry is expected to be earlier by 9, 21, and 29 days in the future normal years 2011-2040, 2041-2070, and 2071-2100, respectively. Southern coastal areas might experience springs with incomplete or even no Japanese cherry flowering caused by insufficient chilling for breaking bud dormancy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.28-34
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• 2020

A reservoir is defined as an artificial facility that stores and controls water during floods and droughts. Korea has constructed and managed reservoirs all over the country to benefit farming communities. The importance of reservoirs has decreased gradually due to urbanization and the spread of tap water, but the importance of water is increasing because of the recent shortage of water and the resulting rise in the price of water resources. Therefore, this study suggests countermeasures through an analysis of the used threshold for agricultural reservoirs. To this end, the forecast of rainfall up to 2100 was first analyzed using flood estimates and RCP scenarios through rainwater data collection. The increase in the RCP 8.5 scenario, the largest increase in the probability rainfall, was calculated by adding it to the current probability rainfall, and it was predicted that the marginal height of Odong Dam would reach its limit in 2028. Therefore, as a countermeasure against this, the measures to secure effective water storage were suggested through measures, such as lowering the height of Yeosu and installing movable beams. Overall, it is expected that effective management of the reservoirs used for agriculture will be possible in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.42-48
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• 2016

Inundation Maps are used to predict potential areas of flooding through the signs of past flooding and flood inundation analysis for flooding expected in the future, and this has led to the development of various forms of disaster-related services by governments. However, each institution has its own individual scenarios for making maps for spatial expression. Therefore, the type of spatial information is not standardized and has many forms and structures. In this study, we attempted to design the metadata that would allow Inundation Map information to be shared and used in various fields. The international standard, ISO 19115, and the domestic standards, KS X ISO 19115, TTAS.IS - 19115 and TTAS.KO - 10.0139/R1 of TTA, were used in the design to derive an appropriate standard for comparative analysis by dividing into maintenance, constraints, metadata, spatial reference system, identification, and distribution. It is expected that inundation maps will be easier to utilize and distribute among institutions and private companies by systematically collecting and managing them through the metadata design based vector space information standard developed in this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3071-3080
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• 2015

The increased demand on the transport of both passengers and goods through rail systems implies higher traffic intensity and congestion on the railways, resulting in greater likelihood of accidents and also degraded passenger services. To cope with the issues, development of an integrated communication network for rails has attracted great deal of attention lately. GSM-R is such an example developed in Europe, which seems to have restrictions in providing various communication services due to network speed limit. For the reason, an LTE-based approach is under study in Korea. After the network development, operation management of the network is necessary. Design of operation management systems has been studied little and thus is the objective of this paper. To do so, a conceptual design has been carried out based on model-based approach. Specifically, a context model has first been created using the use case diagram. Then, SysML models of operational scenarios were developed for the management system. The SysML models have alternatively been expressed as EFFBD models to simulate and verify them. Consequently, the result of the conceptual system design for the operation management of the integrated wireless network is expected to be used as a basis for the detailed design later.

• Journal of Chest Surgery
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• v.49 no.5
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• pp.329-336
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• 2016

Background: Guidelines for esophagogastroduodenoscopy (EGD) in the West allow the continued use of warfarin under therapeutic international normalized ratio (INR) level. In Korea, no guidelines have been issued regarding warfarin treatment before EGD. The authors surveyed Korean cardiac surgeons about how Korean cardiac surgeons handle warfarin therapy before EGD using a questionnaire. Participants were requested to make decisions regarding the continuation of warfarin therapy in two hypothetical cases. Methods: The questionnaire was administered to cardiac surgeons and consisted of eight questions, including two case scenarios. Results: Thirty- six cardiac surgeons at 28 hospitals participated in the survey, and 52.7% of the participants chose to stop warfarin before EGD in aortic valve replacement patients without risk factors for thromboembolism. When the patient's INR level was 2, 31% of the participants indicated that they would choose to continue warfarin therapy. For EGD with biopsy, 72.2% of the participants chose warfarin withdrawal, and 25% of the participants chose heparin replacement. In mitral valve replacement patients, 47.2% of the participants chose to discontinue warfarin, and 22.2% of the participants chose heparin replacement. For EGD with biopsy in patients with a mitral valve replacement, 58.3% of the participants chose to stop warfarin, and 41.7% of the participants chose heparin replacement. Conclusion: This study demonstrated that attitudes regarding warfarin treatment for EGD are very different among Korean surgeons. Guidelines specific to the Korean population are required.

• Journal of Korea Water Resources Association
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• v.46 no.5
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• pp.477-490
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• 2013

A rip-current warning index function, which is estimated from the likelihood of rip current quantified based on numerical simulations under various sea environments and is varied according to real-time buoy-observations, was studied to help protect against rip current accidents at Haeundae beach. For the quantification, the definition of likelihood of rip current, which proposed by Choi et al. (2011, 2012b), was employed and estimated based on Boussinesq modelling. The distribution of likelihood of rip current was evaluated by using various simulations according to scenarios established based on physical quantities(i.e., wave parameters) of buoy-observations. To index the likelihood of rip current, empirical functions were derived based on the distribution and adjusted to observational environments. In this study, the observations from June to September in 2011 at Haeundae beach were applied to the rip-current index functions, and its applications into the real events found based on CCTV images were presented and investigated. In addition, limitations and improvements of the rip-current index function were discussed.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.737-751
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• 2002

Water quality in Daechung Lake was predicted for various discharge conditions of Yongdam dam. The same scenarios were applied as in the previous paper by the authors for Keum River water quality modeling. Effects in water quality due to changes in discharge conditions from Yongdam Dam were less distinct to the Daechung Lake than to the inflowing Keum River due to sink processes in the lake. For the minimum flow year, it is appropriate to maintain Yongdam dam discharge rate to 8.9 $m^3$/sec considering the current field conditions and future predictions of TN and TP concentrations of Yongdam dam. Effect of Yongdam dam discharge conditions to the Daechung Lake water quality were stronger for drier years. However it should be noted that the effects were dependent upon the water quality of Yongdam discharge at the same time. Therefore, water quality management effort should be emphasized before the discussion over the discharge volume of Yongdam dam. The input data sets for simulations in this study were formulated using the available data and assumptions based on authors experiences for the fields. Therefore, continued data collection effort will ensure the validity of this study.

• Economic and Environmental Geology
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• v.52 no.5
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• pp.459-469
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• 2019

We present a quantitative evaluation of density, vesicularity and microtextures for coarse lapilli collected from the Jugam Scoria Deposits, northeastern Ulleung Island. Lapilli from the deposits have modal vesicularities of 61% in the lower part and 67% in the upper part, and vesicle populations dominated by non-interconnected subround vesicles. Clasts of modal vesicularity have margin-parallel zonation, with subaerially quenched rims interpreted to preserve "syn-fragmentation" magmatic textures in microlite-free sideromelane rims, grading "post-fragmentation" tachylitic interiors with vesicle and microlite textures that progressively coarsen from rim to interior. Degassing scenarios are linked to syn-fragmentation vesicle textures to demonstrate that the magmas degassed in dominantly closed systems. And diffusion-controlled cooling rates of trachyandesitic pyroclasts in contact with atmosphere are linked to post-fragmentation evolution of vesicle and microlite textures to infer about transportation and dispersal of the pyroclasts in low shooting jets. These textural analyses show that the Jugam eruptions were strictly applied to the strombolian type, analogous to the hawaiian type among any classical subaerial eruption type.