• Ecology and Resilient Infrastructure
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• v.3 no.3
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• pp.189-200
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• 2016

The species distribution model would be a useful tool for understanding how invasive alien species spread over the country and what environmental variables contribute to their distributions. This study is focused on the potential distribution of two invasive alien species, the common ragweed (Ambrosia artemisiifolia) and knotgrass (Paspalum distichum) in the Korean Peninsula. The maximum entropy (Maxent) model was used for the prediction of their distribution by inferring their climatic environmental requirements from localities where they are currently known to occur. We obtained their presence data from the Global Biodiversity Information Facility and the Korean plant species databases and bioclimatic data from the WorldClim dataset. As a results of the modelling, the potential distribution predicted by global occurrence data was more accurate than that by native occurrence data. The variables determining the common ragweed distribution were precipitation of the driest month and annual mean temperature. Both annual and the coldest quarter mean temperatures were critical factors in determining the knotgrass distribution. The Maxent model could be a useful tool for the prediction of alien species invasion and the management of their expansion.

• Journal of Environmental Impact Assessment
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• v.26 no.5
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• pp.291-302
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• 2017

The research was carried out in order to find climate factors which determine the distribution of Eurya japonica, and the potential habitats (PHs) under the current climate and climate change scenario by using species distribution models (SDMs). Four climate factors; the warmth index (WI), the minimum temperature of the coldest month (TMC), summer precipitation (PRS), and winter precipitaion (PRW) : were used as independent variables for the model. Seventeen general circulation models under RCP (Representative concentration pathway) 8.5 scenarios were used as future climate scenarios for the 2050s (2040~2069) and 2080s (2070~2099). Highly accurate SDMs were obtained for E. japonica. The model of distribution for E. japonica constructed by SDMs showed that minimum temperature of the coldest month (TMC) is a major climate factor in determining the distribution of E. japonica. The area above the $-5.7^{\circ}C$ of TMC revealed high occurrence probability of the E. japonica. Future PHs for E. japonica were projected to increase respectively by 2.5 times, 3.4 times of current PHs under 2050s and 2080s. It is expected that the potential of E. japonica habitats is expanded gradually. E. japonica is applicable as indicator species for monitoring in the Korean Peninsula. E. japonica is necessary to be monitored of potential habitats.

• Korean Journal of Environment and Ecology
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• v.30 no.2
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• pp.173-184
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• 2016

Knowledge of the relationships among interspecific competition, spatial distributions and ecological niches plays an important role in understanding biogeographical distribution patterns of species. In this study, the distributional characteristics and ecological niches of the three Viperidae species (Gloydius ussuriensis, G. brevicaudus, and G. saxatilis) in South Korea were determined based on observation data and species distribution model. The effects of interspecific competition on geographical distribution and the division of the ecological niches of the vipers were also examined based on the models of predicted species distribution. The results showed that altitude was the most important environmental variable for their distribution, and the altitudes at which these snakes were distributed correlated with the climate of that region. Although interspecific ecological niches are quite overlapped, their predicted distribution patternsvary by the Taebaek Mountains. When overlaying the distribution models, most of the overlapping habitats were forest areas, which were relatively less overlapped than were the entire research areas. Thus, a parapatric distribution pattern was expected. The abundance of species occurring sympatrically was positively correlated with each other, indicating the lack of serious interspecies competition in this region. In conclusion, although the three Viperidae species in South Korea occupy similar ecological niches, these snakes exhibit parapatric distribution patterns without direct competition. Further research on various geographic variables (e.g., altitude, microhabitat characteristics) using relatively fine grid sizes, as well as further detailed ecological and behavioral research, is needed to determine the causative factors for the parapatric distribution pattern.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.468-468
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• 2016

3차원 동수역학 모델을 이용하여 연안 순환에서 발생하는 이안류의 연직 분포를 조사하였다. 이안류 흐름은 변수심 위에서 발생하는 파의 쇄파와 모멘텀 전달에 의해 발생하는 외해방향의 흐름을 의미하는 것으로 해안의 보전, 유지 및 개발 측면에서 매우 중요한 역할을 한다. 지난 수십년동안 이안류와 관련된 현상을 해석하기 위해 많은 연구들이 수행되어 왔다. 하지만 대부분의 연구들은 수심적분된 2차원 모델을 사용하거나 위상 평균된 3차원 모델을 사용하여 이안류 흐름이 발생할 시 유속의 3차원 분포나 각 종 물리량의 시간적인 변화 등을 모의하기 어려웠다. 본 연구에서는 3차원 동수역학 모델 NHWAVE (Non-Hydrostatic WAVE model)을 이용하여 이안류의 연직분포를 조사하였다. 이안류를 발생시키기 위하여 이상적인 이안류 지형을 만들었으며 여러 지점에서 연직분포를 측정하여 수심적분된 Boussinesq 모델과 비교하여 특성을 파악하였다. 수치모의 수행결과, 두 모델 모두 이안류 현상을 잘 재현하였으나 Boussinesq 모델은 수평유속의 연직방향 변화를 잘 재현하지는 못하였다. 또한, 파고가 상대적으로 큰 경우에는 3차원 모델에서는 작은 순환류가 외해 영역에서 발생하였으나 Boussinesq 모델에서는 관측하지 못하였다.

• Journal of Environmental Impact Assessment
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• v.33 no.2
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• pp.53-63
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• 2024

Biodiversity holds significant importance within the framework of environmental impact assessment, being utilized in site selection for development, understanding the surrounding environment, and assessing the impact on species due to disturbances. The field of environmental impact assessment has seen substantial research exploring new technologies and models to evaluate and predict biodiversity more accurately. While current assessments rely on data from fieldwork and literature surveys to gauge species richness indices, limitations in spatial and temporal coverage underscore the need for high-resolution biodiversity assessments through species richness mapping. In this study, leveraging data from the 4th National Ecosystem Survey and environmental variables, we developed a species distribution model using Random Forest. This model yielded mapping results of 24 mammalian species' distribution, utilizing the species richness index to generate a 100-meter resolution map of species richness. The research findings exhibited a notably high predictive accuracy, with the species distribution model demonstrating an average AUC value of 0.82. In addition, the comparison with National Ecosystem Survey data reveals that the species richness distribution in the high-resolution species richness mapping results conforms to a normal distribution. Hence, it stands as highly reliable foundational data for environmental impact assessment. Such research and analytical outcomes could serve as pivotal new reference materials for future urban development projects, offering insights for biodiversity assessment and habitat preservation endeavors.

• Korean Journal of Environment and Ecology
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• v.31 no.4
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• pp.381-396
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• 2017

Understanding species distribution plays an important role in conservation as well as evolutionary biology. In this study, we applied a species distribution model to predict hotspot areas and habitat characteristics for endangered herpetofauna species in South Korea: the Korean Crevice Salamander (Karsenia koreana), Suweon-tree frog (Hyla suweonensis), Gold-spotted pond frog (Pelophylax chosenicus), Narrow-mouthed toad (Kaloula borealis), Korean ratsnake (Elaphe schrenckii), Mongolian racerunner (Eremias argus), Reeve's turtle (Mauremys reevesii) and Soft-shelled turtle (Pelodiscus sinensis). The Kori salamander (Hynobius yangi) and Black-headed snake (Sibynophis chinensis) were excluded from the analysis due to insufficient sample size. The results showed that the altitude was the most important environmental variable for their distribution, and the altitude at which these species were distributed correlated with the climate of that region. The predicted distribution area derived from the species distribution modelling adequately reflected the observation site used in this study as well as those reported in preceding studies. The average AUC value of the eigh species was relatively high ($0.845{\pm}0.08$), while the average omission rate value was relatively low ($0.087{\pm}0.01$). Therefore, the species overlaying model created for the endangered species is considered successful. When merging the distribution models, it was shown that five species shared their habitats in the coastal areas of Gyeonggi-do and Chungcheongnam-do, which are the western regions of the Korean Peninsula. Therefore, we suggest that protection should be a high priority in these area, and our overall results may serve as essential and fundamental data for the conservation of endangered amphibian and reptiles in Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1731-1740
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• 2013

The design life and durability of the bridges are strongly affected by the Gross Vehicle Weight(GVW) of heavyweight trucks. The Weigh-In-Motion(WIM) systems are typically used to collect information on truck total weight and speed. The statistical analysis of the GVW measured using High Speed WIM systems showed that most of heavy vehicles were from Vehicle Type 7, 10, and 12. The analysis was also carried out to determine goodness of fit with theoretical probability distributions. The normal distribution was shown to best describe the overall distribution of GVW. The top 10% of the GVW appeared to best fit by the Weibull 3 probability distribution.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.410-413
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• 2003

본 논문에서는 네트워크가 막연히 무작위적이라고 하기에는 사회나 세포, 인터넷 등이 어떤 법칙에 따라 짜연진 것처럼 보인다. 하지만 복잡한 네트워크의 모습이 네트워크의 모델과 실제로 똑같은지를 비교하기는 그리 쉬운 문제가 아니다. 무작위적 네트워크의 경우는 수학적으로 엄밀히 말하자면 쁘아송분포를 따른다. 쁘아송분포에서는 모든 점들이 동일한 확률로 여러 점들에 연결되는 기회를 갖는다. 즉 균일한 분포이다. 따라서 상당히 적거나 반대로 상당히 많은 수의 연결선을 가진 점은 극히 드물다. 이 경우 연결선 분포가 종 모양이 된다. 대부분의 점들이 곡선에 해당하는 연결선 수를 갖게 된다. 본 논문에서 쁘아송분포와 회귀분석을 통하여 하나 또는 둘 이상의 변수들 사이에 어떤 관계를 함수관계로 나타내어 분석하는 방법을 보이고 회귀분석 방법에 의해서 미래를 예측하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.360-361
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• 2018

지구관측데이터 공동활용체계로 GEOSS가 제안되면서 한국에서도 K-GEOSS 개발을 통하여 다양한 방식으로 지구관측데이터의 활용 확산에 참여하고 있다. 본 연구에서는 K-GEOSS 시범서비스로 환경 분야의 생물 종 분포 변화 예측 시나리오를 개발하여 미래 생물 종의 서식지 보호를 위한 지구관측데이터의 효과적 사용 사례를 보여준다. 이러한 시범서비스는 K-DMSS 플랫폼을 이용하여 개발하였으며, 데이터 수집 전처리, 모델 학습 평가, 실제 분포 변화 예측까지 모두 자동화하여 수행한다. 최종단에서 다양한 기후모델 및 기후변화 시나리오에 따른 여러 종류의 예측 결과를 제공함으로써 대체 서식지 보호 및 정책수립을 위한 종합적인 의사결정에 도움을 주도록 하였다. 이와 같은 다양한 종류의 시범서비스 개발 및 지구관측데이터의 공동활용 사례 발굴을 통하여 GEOSS 체계의 정착을 보다 앞당길 수 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.857-862
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• 2011

3 dimensional turbine exhaust gas flow was simplified to an axisymmetrical flow and calculated with detailed chemistry models. GRI 35 species-217 reaction step model and simplified 11 species 15 reaction model was applied to the secondary reaction of the turbine exhaust gas and compared. All the model captured the secondary combustion on the base region, and the temperature was 600K higher than that without turbine exhaust gas. This means the local temperature of the base can be higher in the case of real 3 dimensional flow. The simplified model show the similar results to the GRI detailed chemistry model although the former affected the engine plume structure slightly.