• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.685-694
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• 2018

We measured ecological niche space (ENS) using carbon and nitrogen stable isotope ratios of benthic macroinvertebrates to estimate its applicability for large river assessment. In particular, we compared ENSs of selected macroinvertebrates between upper and lower area of Seungchon Weir in Yeongsan River to estimate the impact of weir on biological community. We also measured basic water quality and community indices including benthic macroinvertebrates index (BMI) to estimate their correlations with calculated ENS. ENS was calculated using the Bayesian Stable Isotope in R statistics (package "SIBER"). The results showed that seasonal variations in water quality and community indices were found, but there was no apparent tendency between upper and lower area of the Seungchon Weir in June (before rainy season) and August (after rainy season). However, ENS of benthic macroinvertebrates markedly decreased across the weir in both June and August regardless of changes in water quality. This means the physical change of the stream due to the weir cause decrease of ecological isotopic niche space of benthic macroinvertebrates regardless of water quality, suggesting physical modification by the weir can affect the interaction between habitat condition and macroinvertebrates. Therefore, the ecological isotopic niche space can be a useful supplementary indicator for the river ecosystem assessment.

• Advanced Industrial SCIence
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• v.2 no.3
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• pp.22-28
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• 2023

In this study, we conducted research on the automated trading of U.S. stocks through a volatility strategy using the Fear and Greed index. Volatility in the stock market is a common phenomenon that can lead to fluctuations in stock prices. Investors can capitalize on this volatility by implementing a strategy based on it, involving the buying and selling of stocks based on their expected level of volatility. The goal of this thesis is to investigate the effectiveness of the volatility strategy in generating profits in the stock market.This study employs a quantitative research methodology using secondary data from the stock market. The dataset comprises daily stock prices and daily volatility measures for the S&P 500 index stocks. Over a five-year period spanning from 2016 to 2020, the stocks were listed on the New York Stock Exchange (NYSE). The strategy involves purchasing stocks from the low volatility group and selling stocks from the high volatility group. The results indicate that the volatility strategy yields positive returns, with an average annual return of 9.2%, compared to the benchmark return of 7.5% for the sample period. Furthermore, the findings demonstrate that the strategy outperforms the benchmark return in four out of the five years within the sample period. Particularly noteworthy is the strategy's performance during periods of high market volatility, such as the COVID-19 pandemic in 2020, where it generated a return of 14.6%, as opposed to the benchmark return of 5.5%.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.516-529
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• 2021

Coniferous forests in the Baekdudaegan protected area are gradually losing their landscape diversity and uniqueness along with their ecological stability due to changes in vegetation composition and structures caused by various disturbance factors, such as climate change, vegetation succession, and human interference. This study provides basic data for establishing a comprehensive conservation plan for coniferous forests in the Baekdudaegan protected area. We classified the vegetation unit types using the Zurich-Montpellier School of Phytosociology and two-way indicator species analysis methods and analyzed the species diversity and structural characteristics based on the vegetation information of 755 stands collected in the natural resources change survey of the Baekdudaegan mountains (2016 to 2020) by the Korea Forest Service. Therefore, the vegetation of the coniferous forests of theBaekdudaegan protected area was classified into 15 types under the vegetation unit hierarchy of two community groups, four communities, seven sub-communities, and 14 variants. Furthermore, we compared the total coverage among vegetation types, importance values, constancy classes, life-forms, and diversity indices. Additionally, the average total coverage and number of species per 100 m² of all coniferous forests were 232% and 21 species, respectively, with the species diversity and dominance indices averaging 1.907 and 0.222, respectively.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.5 s.45
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• pp.63-74
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• 2005

The purpose of this study is to assess the seismic performance of reinforced concrete bridge columns using inelastic finite element analysis. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Damage index aims to provide a means of quantifying numerically the damage in reinforced concrete bridge columns sustained under earthquake loading. The proposed numerical method for the seismic performance assessment of reinforced concrete bridge columns is verified by comparison with reliable experimental results.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.21-33
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• 2006

The purpose of this study is to assess the seismic performance of reinforced concrete bridge columns using nonlinear finite element analysis. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Damage index aims to provide a means of quantifying numerically the damage in reinforced concrete bridge columns sustained under earthquake loading. The proposed numerical method for the seismic performance assessment of reinforced concrete bridge columns is verified by comparison with reliable experimental results.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.11
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• pp.619-630
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• 2015

This study was conducted to propose the methodology of human risk assessment specialized to domestic mine areas and to quantify the human risk of heavy metal (As, Cd, Cu, Pb, and Zn) contamination around two abandoned metal mines. To attain the goals, we established a relevant exposure scenario, including 7 exposure pathways and extracted a variety of exposure factors reflecting the characteristics of inhabitants around abandoned metal mine areas. Finally, carcinogenic and non-carcinogenic risks were compared between two areas, exposure pathways, heavy metal contaminants, and receptors. The total excess carcinogenic risks of two mine areas of concern were calculated to be larger than the acceptable carcinogenic risk ($1{\times}10^{-6}$), indicating those two areas are not safe for carcinogenic hazard. In addition, the hazard indices of two areas were computed to be higher than unit risk (1), suggesting that the areas of concern have non-carcinogenic risk. Ingestion of crop and intake of groundwater were evaluated to be main exposure pathways contributing to carcinogenic and non-carcinogenic risks within the areas. Also, the results show that carcinogenic and non-carcinogenic hazards were mostly attributed to As and As, Cd, and Pb, respectively.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.891-901
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• 2021

In this study, a hydrological cycle soundness evaluation method was developed using monthly meteorological observation data. The Gyeongan stream watershed was divided into five sub-basins and eight criteria were established for hydrological cycle evaluation: the number of non-rainfall day, the number of non-rainfall day fluctuation, over 30 mm per day, over 30 mm per day fluctuation, average river level, average river level fluctuation, average groundwater level and average groundwater level fluctuation. Observation data were normalized and weights for evaluation by each sub-basin were calculated using the entropy method. The hydrological cycle soundness evaluation indices were calculated using TOPSIS applying the calculated weight value. As a result of the study, it was found that the hydrological cycle soundness was unstable in the Gyeongan-upstream from November to January, the Gyeongan-suwipyo from February to April, Gonjiam stream from April to May, and the Gyeongan-downstream from November to February. In this study, the developed technique is expected to serve as a quantitative basis for policy decision to recover hydrological cycle soundness.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.4_1
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• pp.343-351
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• 2014

The correlation between regional Walkability Index and their physical socio-economic characteristics has evaluated by the spatial statistical analysis to understand the urban pedestrian environments, where has been emerging the significance, recently. Following to the study, the Walkability Indexes were calculated quantitatively from two administrative districts of Busan and measured Global Local spatial autocorrelation indices. Additionally, the Geographically Weighted Regression model was applied to define the correlation between Walkability Indexes and urban environmental variables. The spatial autocorrelation values and clusters on the Walkability Indexes were derived in statistically significant level. Furthermore, the Geographically Weighted Regression model has been derived more improved inference than the OLS regression model, so as the influence of local level pedestrian environment was identified. The results of this study suggest that the spatial statistical approach can be effective on quantitative assessing the pedestrian environment and navigating their associated factors.

• Journal of Environmental Policy
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• v.5 no.4
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• pp.51-84
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• 2006

The current study suggested plans to maintain excellent natural environment of national parks by prohibiting excessive use and introduced the concept of environment capacity using GIS. This paper is that researches on National Parks in the past studied were mostly on the natural resources, human resources, facilities and visitors as well as standard for management of these issues from individual perspective, this study defined concept of integrated (principle of overlay) carrying capacity. It also estimated environmental ecological conservation value considering ecological conservation and environment-ecological index and estimated visit attraction index based on attraction value of nature and facilities in the parks. And it suggested management index as a management plan for effective analysis and management of carrying capacity. As a result, in case of Mt. Jiri National Park, Grade 5 area requiring inducement occupied 71% while Grade 1 area requiring dispersion occupied 0.1%, which means the necessity of appropriate dispersion in the site. Moreover, this research aims to find a monitoring method, utilizing the concept of ubiquitous, for the continuous systematic monitoring on immense natural resources, facilities, and visitors. The continuable national park management plan was proposed by establishing quantitative, and qualitative objective of the environment capacity from the decision based on GIS public opinions from the gathered information. Through the GIS public opinion system and ubiquitous based technology, I propose the effective management technology method for national park.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.179-190
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• 2019

In this study, a fish survey was conducted to investigate the habitat status of black shinner (Pseudopungtungia nigra) designated as endangered species level from the lower part of Yongdam Dam to the upper part of Daecheong Dam. Biodiversity analysis was performed on the basis of the number of fish emerged, and biological health and physical habitat environment were quantitatively analyzed using collected P. nigra. According to the survey, the habitat range of P. nigra was found from Banguri-myeon, Buri-myeon, Geumsan-gun, downstream of Yongdam Dam. The biodiversity analysis results of all species appeared to be low in overall dominance index and relatively high in species diversity and uniformity index. In addition, P. nigra collected in this study was confirmed to have normal growth and nutritional status by the full-length-weighted relativities and condition factor. The physical habitat environment of P. nigra was 0.3 - 0.6 m in depth, 0.3 - 0.7 m/s in flow rate, and bed materials showed high frequency of occurrence in the range of cobbles (64.0 - 256.0 mm) to boulders (>256.0 mm). These results are expected to be used as data for habitat restoration and management in the future as basic data on the spatial range and preferred physical habitat environment of P. nigra in Geumgang.