• Journal of Life Science
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• v.25 no.4
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• pp.369-375
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• 2015

Data on the spatial distribution of a plant population among administrative areas is useful for various purposes. In this study, I analyzed the spatial distribution of the geographical distances of Carex siderosticta at Mt. Geumjeong and Mt. Ahop in Korea. The aim was to test a spatial structure within two populations of C. siderosticta. Most natural plots of C. siderosticta are not uniformly distributed in the forest community; for example, uniform plots were aggregately distributed within a space of 6.0 m $\times$ 6.0 m. When the sampling plots were larger than 6.0 m $\times$ 12.0 m, the individuals of C. siderosticta were aggregately distributed. The neighboring patches of C. siderosticta were predominantly 7.5 m to 9.0 m apart, on average; however, if the natural populations were disturbed by human activities, the aggregation occurred in shorter distances than a scale of 9.0 m. Moran's I of C. siderosticta significantly differed from the expected value in only 16 of 40 cases (40%). In conclusion, the geographical distribution of C. siderosticta is not even, with varying degrees of size in the plots, while human activities give rise to density effects in the plots at both Mt. Geumjeong and Mt. Ahop in Korea.

• Korean Journal of Remote Sensing
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• v.12 no.2
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• pp.155-168
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• 1996

Speckle noise has been a primary concern to many applications of synthetic aperture radar (SAR) imagery. In recent years, several satellites with radar imaging systems were launched and the use of SAR data are expected to be increased rapidly The objectives of this study are to provide introductory understanding on radar speckle filtering and to compare the effects of several filtering methods that are relatively unknown to user community. Two study sites were extracted from the RADARSAT SAR data obtained over the suburban areas near Seoul. The study sites include relatively homogeneous cover types, such as reservoir, parking lot, rice pad, and deciduous forest. Five filters (mean filter, median filter, sigma filter, local statistics filter, and autocorrelation filter) were applied to the SAR imagery and their effects were evaluated from the aspects of both image smoothing and edge preservation. In overall, the evaluation results indicate that the local statistics filter and autocorrelation filter, that are based on a speckle model, are more effective to suppress speckle within homogeneous cover type while maintaining the edge sharpness between cover types.

• Korean Journal of Agricultural Science
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• v.46 no.1
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• pp.205-217
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• 2019

The aim of this study was to identify land resources because food production and supply in North Korea have been at risk due to variations in its seasonal climate. More than three-fifths of the soils are locally derived from the weathering of granitic rocks or various kinds of schists developed from crystalline rocks. Well-developed reddish brown soils derived from limestone are found in the North Hwanghae province and in the southern part of the South Pyeongan province. Additionally, a narrow strip of similarly fertile land runs through the eastern seaboard of the Hamgyong and Kangwon Provinces. The loss of clay particles and organic matter are major causes of degradation in the soil physical and chemical properties in North Korea. 75% of the areas converted from forests became croplands, and 69% of the land converted to croplands came from forests. The net forest loss was quite small from the 1990s to the 2000s. However, deforestation in areas with a slightly lower elevation and gentler slope between 1997 and 2014 led to severe soil erosion resulting in a drastic change in the physical and chemical properties of the soil which influenced cropland stability and productivity. Therefore, the drastic changes in land cover as well as in the physical and chemical properties of the soil caused by various geographical features have seriously influenced the productivity of crops in North Korea.

• Korean Journal of Ornithology
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• v.25 no.2
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• pp.126-132
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• 2018

For balanced development of ornithological research in Korea, it is important to review what birds and what research topics have been studied so far. We quantitatively investigated the trends of domestic ornithological research using text-mining and co-word analysis. As a result of studying 372 articles published in the Korean Journal of Ornithology, which is the most representative ornithological journals, words related to research topics such as population and community monitoring, first record of species and breeding ecology, and heavy metal pollution in birds have been widely used in research articles. Except for subjects such as monitoring and first record of species, studies have not been conducted widely. It was also found that research were concentrated on specific birds such as Anas platyrhynchos, Calidris alpina, and Anas poecilorhyncha. The present study, which analyzed the research topics and avian taxa that were relatively active until now and those which were insufficient, suggests what we should do in the future for the balanced development of ornithological research in Korea.

• Journal of Korean Society of Rural Planning
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• v.24 no.4
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• pp.69-80
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• 2018

In this study, we typified the project for revitalizing the rural area through text analysis using news data, and analyzed the main direction and characteristics of the project. In order to examine the factors emphasized among the issues related to the revitalization of rural areas, we used news data related to 'tourism' and 'livelihood', which are the main keyword of the project to promote rural areas. In the analysis, text mining techniques were used. Topic modeling was conducted on LDA techniques for major projects in 'tourism' and 'livelihood' keyword. Based on this, this study typified the projects that are carried out for the activation of rural areas by topic. As a result of the analysis, it was fount that the topics included in the project were distributed in 11 sub-types(Tourism Promotion, Regional Specialization, Local Festival, Development of Regional Scale, Urban and Rural Exchange, Agricultural Support, Community Forest Management, Improve the Settlement Environment, General Welfare Service, Low Class Support, Others). The characteristics of the rural revitalization projects were examined, and it was confirmed that domestic projects were carried out by tourism-oriented projects. To summarize, the government is making projects to revitalize rural areas through related ministries. Within the structure where the project is spreading to the region, a lot of projects are being carried out. It is understood that the tourism and welfare oriented projects are being carried out in the revitalization project of the domestic rural area. Therefore, in order to achieve the goal of rural revitalization, it is believed that it will be effective to carry out a balanced project to improve the settlement environment of the residents.

• Atmosphere
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• v.29 no.1
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• pp.1-12
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• 2019

For the allergy patient who needs to know the situation about the extent of pollen risk, the National Institute of Meteorological Sciences developed a pollen forecasting system based on the Community Multiscale Air Quality Modeling (CMAQ). In the old system, pollen emission from the oak was estimated just based on the airborne concentration and meteorology factors, resulted in high uncertainty. For improving the quality of current pollen forecasting system, therefore the estimation of pollen emission is now corrected based on the observation of pollen emission at the oak forest to better reflect the real emission pattern. In this study, the performance of the previous (NIMS2014) and current (NIMS2016) model system was compared using observed oak pollen concentration. Daily pollen concentrations and emissions were simulated in pollen season 2016 and accuracy of onset and end of pollen season were evaluated. In the NIMS2014 model, pollen season was longer than actual pollen season; The simulated pollen season started 6 days earlier and finished 13.25 days later than the actual pollen season. The NIMS2016 model, however, the simulated pollen season started only 1.83 days later, and finished 0.25 days later than the actual pollen season, showing the improvement to predict the temporal range of pollen events. Also, the NIMS2016 model shows better performance for the prediction of pollen concentration, while there is a still large uncertainty to capture the maximum pollen concentration at the target site. Continuous efforts to correct these problems will be required in the future.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.1
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• pp.70-75
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• 2021

The present study aimed to clarify flora living at the area of Restoration Center for Endangered Species in Yeongyang, Gyeongbuk Province. In May, August, and September 2019 and in May and July 2020, all of vascular plants were recorded, and endangered, Korea endemic, and exotic plant species were further identified. The study site contained a total of 418 floral taxa (98 families, 261 genera, 384 species, 4 subspecies, 27 variations, and 3 formations), in which Magnoliophyta accounted for larger proportion (95.2%) than Pteridophyta (3.6%) and Pinophyta (1.2%). In addition, 1 endangered (Cypripedium macranthos Sw.) and 5 Korea endemic species (Aconitum pseudolaeve Nakai, Eleutherococcus divaricatus var. chiisanensis [Nakai] C.H. Kim & B.-Y. Sun, Lonicera subsessilis Rehder, Paulownia coreana Uyeki, and Weigela subsessilis [Nakai] L.H. Bailey) were detected. The number of exotic species was 33, consisting of 4 invasive-exotic, 4 potentially invasive-exotic, and 25 non-invasive species. Compared to a previous assessment before the establishment of the center (in 2014), there were increases in total floral taxa (from 361 to 418), endangered species (from 0 to 1), and exotic species (from 26 to 33). These results possibly reflect temporal changes in floral community, which should be confirmed through subsequent long term monitoring.

• Journal of Ecology and Environment
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• v.45 no.1
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• pp.62-71
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• 2021

The climate is changing rapidly, and this may pose a major threat to global biodiversity. One of the most distinctive consequences of climate change is the poleward and/or upward shift of species distribution ranges associated with increasing temperatures, resulting in a change of species composition and community structure in the forest ecosystems. The Baekdudaegan mountain range connects most forests from the lowland to the subalpine zone in South Korea and is therefore recognized as one of the most important biodiversity hotspots. This study was conducted to understand the distribution range of vascular plants along elevational gradients through field surveys in the six national parks of the Baekdudaegan mountain range. We identified the upper and lower distribution limits of a total of 873 taxa of vascular plants with 117 families, 418 genera, 793 species, 14 subspecies, 62 varieties, two forms, and two hybrids. A total of 12 conifers were recorded along the elevational gradient. The distribution ranges of Abies koreana, Picea jezoensis, Pinus pumila, and Thuja koraiensis were limited to over 1000 m above sea level. We also identified 21 broad-leaved trees in the subalpine zone. A total of 45 Korean endemic plant species were observed, and of these, 15 taxa (including Aconitum chiisanense and Hanabusaya asiatica) showed a narrow distribution range in the subalpine zone. Our study provides valuable information on the current elevational distribution ranges of vascular plants in the six national parks of South Korea, which could serve as a baseline for vertical shifts under future climate change.

• Smart Structures and Systems
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• v.29 no.1
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• pp.93-103
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• 2022

With the wider availability of sensor technology through easily affordable sensor devices, several Structural Health Monitoring (SHM) systems are deployed to monitor vital civil infrastructure. The continuous monitoring provides valuable information about the health of the structure that can help provide a decision support system for retrofits and other structural modifications. However, when the sensors are exposed to harsh environmental conditions, the data measured by the SHM systems tend to be affected by multiple anomalies caused by faulty or broken sensors. Given a deluge of high-dimensional data collected continuously over time, research into using machine learning methods to detect anomalies are a topic of great interest to the SHM community. This paper contributes to this effort by proposing a relatively new time series representation named "Shapelet Transform" in combination with a Random Forest classifier to autonomously identify anomalies in SHM data. The shapelet transform is a unique time series representation based solely on the shape of the time series data. Considering the individual characteristics unique to every anomaly, the application of this transform yields a new shape-based feature representation that can be combined with any standard machine learning algorithm to detect anomalous data with no manual intervention. For the present study, the anomaly detection framework consists of three steps: identifying unique shapes from anomalous data, using these shapes to transform the SHM data into a local-shape space and training machine learning algorithms on this transformed data to identify anomalies. The efficacy of this method is demonstrated by the identification of anomalies in acceleration data from an SHM system installed on a long-span bridge in China. The results show that multiple data anomalies in SHM data can be automatically detected with high accuracy using the proposed method.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.53-65
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• 2022

Most of the reservoirs managed by the city and county are small and it is difficult to respond to climate change because the drainage area is small and the inflow increases rapidly when a heavy rain occurs. In this study, the current status of reservoirs managed by city and county in Gyeonggi-do was reviewed and flood vulnerability due to climate change was analyzed. In order to analyze the impact of climate change, CMIP6-based future climate scenario provided by IPCC was used, and future rainfall data was established through downscaling of climate scenario (SSP8-8.5). The flood vulnerability of reservoirs due to climate change was evaluated using the concept provided by the IPCC. The future annual precipitation at six weather stations appeared a gradual increase and the fluctuation range of the annual precipitation was also found to increase. As a result of calculating the flood vulnerability index, it was analyzed that the flood vulnerability was the largest in the 2055s period and the lowest in the 2025s period. In the past period (2000s), the number of D and E grade reservoirs was 58, but it was found to increase to 107 in the 2055s period. In 2085s, there were 17 E grade reservoirs, which was more than in the past. Therefore, it is necessary to take measures against the increasing risk of flooding in the future.