• Journal of the Korean Association of Geographic Information Studies
• /
• v.17 no.3
• /
• pp.20-38
• /
• 2014

Vegetation phenology is the most important indicator of ecosystem response to climate change. Therefore it is necessary to continuously monitor forest phenology. This paper analyzes the phenological characteristics of forests in South Korea using the MODIS vegetation index with error from clouds or other sources removed using the HANTS algorithm. After using the HANTS algorithm to reduce the noise of the satellite-based vegetation index data, we were able to confirm that phenological transition dates varied strongly with altitudinal gradients. The dates of the start of the growing season, end of the growing season and the length of the growing season were estimated to vary by +0.71day/100m, -1.33day/100m and -2.04day/100m in needleleaf forests, +1.50day/100m, -1.54day/100m and -3.04day/100m in broadleaf forests, +1.39day/100m, -2.04day/100m and -3.43day/100m in mixed forests. We found a linear pattern of variation in response to altitudinal gradients that was related to air temperature. We also found that broadleaf forests are more sensitive to temperature changes compared to needleleaf forests.

• Journal of the Korean Regional Science Association
• /
• v.34 no.4
• /
• pp.19-34
• /
• 2018

The purpose of this study is to analyze the seasonal issues using the local newspaper articles with the keyword beach from 2004 to 2017. Topic modeling and Time series regression analysis based on open source programs were performed for analysis. Topic modeling results showed 35 topics in spring, 47 topics in summer, 36 topics in autumn and 35 topics in winter. The common themes were 'beaches', 'festivals and events', 'accident and environmental issues', 'tourism', 'development and sale', 'administration and policy' and 'weather'. Time series regression analysis showed in the spring, 5 Hot-Topics and 2 Cold-Topic were found out of the 35 topics. In the summer, 6 Hot-Topics and 3 Cold-Topic were found out of the 47 topics. In the autumn, 4 Hot-Topics and 3 Cold-Topic were found out of the 36 topics. In the winter, 3 Hot-Topics and 3 Cold-Topic were found out of the 35 topics. And for each season, topics that do not fall into the Hot-Topic and Cold-Topic are classified as Neutral-Topic. In this study if seasonal uses are different such as beaches are deemed that seasonal topic modeling for analysis of regional issues will yield more useful results and enable detailed diagnosis.

• Journal of Korean Society of Forest Science
• /
• v.109 no.4
• /
• pp.361-370
• /
• 2020

Long-term observation of the life cycle of plants allows the identification of critical signals of the effects of climate change on plants. Indeed, plant phenology is the simplest approach to detect climate change. Observation of seasonal changes in plants using digital repeat imaging helps in overcoming the limitations of both traditional methods and satellite remote sensing. In this study, we demonstrate the utility of camera-based repeat digital imaging in this context. We observed the biological events of plants and quantified their phenophases in the northern temperate type deciduous broadleaf forest of Jeombong Mountain. This study aimed to identify trends in seasonal characteristics of Quercus mongolica (deciduous broadleaf forest) and Pinus densiflora (evergreen coniferous forest). The vegetation index, green chromatic coordinate (GCC), was calculated from the RGB channel image data. The magnitude of the GCC amplitude was smaller in the evergreen coniferous forest than in the deciduous forest. The slope of the GCC (increased in spring and decreased in autumn) was moderate in the evergreen coniferous forest compared with that in the deciduous forest. In the pine forest, the beginning of growth occurred earlier than that in the red oak forest, whereas the end of growth was later. Verification of the accuracy of the phenophases showed high accuracy with root-mean-square error (RMSE) values of 0.008 (region of interest [ROI]1) and 0.006 (ROI3). These results reflect the tendency of the GCC trajectory in a northern temperate type deciduous broadleaf forest. Based on the results, we propose that repeat imaging using digital cameras will be useful for the observation of phenophases.

• Journal of Wetlands Research
• /
• v.24 no.4
• /
• pp.301-311
• /
• 2022

The purpose of this study is to analyze the seasonal characteristics of water quality using long-term water quality monitoring data. Seasonal characteristics of water quality were analyzed using monitoring data from 34 tributaries where long-term monitoring was performed in the Nakdong River system, and average data analysis of water quality, coefficient of variation analysis, and trend analysis were performed for seasonal analysis. For seasonal analysis, average data analysis of water quality, coefficient of variation analysis, and trend analysis were performed. As a result of the evaluation of the coefficient of variation, tributaries were larger than main streams, and BOD, T-P, and TOC were larger in autumn and T-N were larger in spring. Trend analysis was analyzed using Mann-Kendall and Sen's Slope. BOD, T-N, and T-P tended to decrease, but TOC had a lot to increase. Through this study, it was possible to evaluate the availability of long-term water quality monitoring data and analyze seasonal characteristics, and to analyze the stabilization period of water quality and changes in pollutant sources for watershed management.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.3
• /
• pp.337-352
• /
• 2023

In general, Rainfall-Runoff model parameter set is optimized using the entire data to calculate unique parameter set. However, Korea has a large precipitation deviation according to the season, and it is expected to even worsen due to climate change. Therefore, the need for hydrological data considering seasonal characteristics. In this study, we conducted regional sensitivity analysis(RSA) using the conceptual Rainfall-Runoff model, GR4J aimed at the Soyanggang dam basin, and clustered combining the RSA results with hydrometeorological data using Self-Organizing map(SOM). In order to consider the climate characteristics in parameter estimation, the data was divided based on clustering, and a calibration approach of the Rainfall-Runoff model was developed by comparing the objective functions of the Global Optimization method. The performance of calibration was evaluated by statistical techniques. As a result, it was confirmed that the model performance during the Cold period(November~April) with a relatively low flow rate was improved. This is expected to improve the performance and predictability of the hydrological model for areas that have a large precipitation deviation such as Monsoon climate.

• Journal of the Korean association of regional geographers
• /
• v.19 no.3
• /
• pp.446-453
• /
• 2013

Festivals using plant phenology is one of the examples can represent the ecosystem services. Changwon Jinhae Gunhangje is typical spring festival using cherry blossoms phenology. This research was done to define relationship between flowering of cherry blossoms and Gunhangje. Phenological data (Julian day) of cherry blossoms and visitor number of Gunhangje from 1987 to 2013 were collected. Differences of Phenological phase of cherry blossoms and duration of Gunhangje was analyzed. Trend analysis was performed to know changes of flowering and budding day of cherry blossoms. Correlations between visitor number of Gunhangje and environmental factors was defined by factor analysis and regression analysis. Results are showed that during the 26 years, periodicity of flowering and budding day was not identified or even identified it was not significant. Environmental factors effect on visitor numbers of Gunhangje were defined as temperature factor, day factor, and precipitation factor. Temperature factor was significantly correlated with visitor numbers of Gunhangje. Though Flowering day of cherry blossoms and festival duration was not matched, however, difference of visitor numbers was not showed. These results suggest that fixed duration of Gunhangje would be more effective to visitors than changing the festival duration following the phenological day changes of cherry blossoms.

• Journal of the Korean Geographical Society
• /
• v.42 no.6
• /
• pp.835-850
• /
• 2007

This study examines long-term trends of onset dates and durations of season decomposed by applying a lowpass filtering using observed 80-year(1921-2000) data and projected 2040s and 2090s data based on the IPCC SRES A1B emission scenario in South Korea. As recent climate changes on seasonal cycles in South Korea, the onset dates of spring and summer began earlier after 1970s. But onset dates of autumn and winter were delayed. Winter duration was more shortened during the post-1990 period. Summer duration is longer and winter duration is shorter at southern and eastern coastal area. The different of summer duration and winter duration in coastal area was longer than over the inland. The reduction in winter duration in South Korea agrees with results in overall global warming trends as a climate change signal. Future model output data predict that winter will disappear in Gangneung, Busan and Mokpo in the 2090s

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.9
• /
• pp.56-65
• /
• 2019

This study empirically analyzes the effect of weather on pedestrian volume in an urban space. We used data from the 2009 Seoul Flow Population Survey and constructed a model with the pedestrian volume as a dependent variable and the weather and physical environment as independent variables. We constructed 28 models and compared the results to determine the effects of weather on pedestrian volume by season, land use, and time zone. A negative binomial regression model was used because the dependent variable did not have a normal distribution. The results show that weather affects the volume of walking. Rain reduced walking volume in most models, and snow and thunderstorms reduced the volume in a small number of models. The effects of the weather depended on the season and land use, and the effects of environmental factors depended on the season. The results have various policy implications. First, it is necessary to provide semi-outdoor urban spaces that can cope with snow or rain. Second, it is necessary to have different policies to encourage walking for each season.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2019.10a
• /
• pp.372-374
• /
• 2019

기계를 잘 다루지 못하는 사람들은 스마트폰을 활용할 때 어려움을 겪는다. 따라서 기계에 서툰 사람뿐 아니라 날씨를 확인하기 힘든 바쁜 현대인들이 날씨를 시각적으로 좀 더 쉽게 확인하고, 필요한 용품을 미리 챙겨서 날씨에 대비할 수 있도록 한다. 그뿐만 아니라 사계절이 없는 나라의 사람들에게 다양한 계절을 경험할 수 있게 해준다. 터치스크린을 이용해서 사용자가 원하는 나라를 선택하면 날씨 정보가 화면에 나타나고, 날씨 박스에도 시각적으로 표현이 된다. 날씨 박스로는 인형 소품을 이용해 계절을 알려주고, 조명을 이용해서 황사, 미세먼지 그리고 낮과 밤을 나타내고, 효과음을 이용해서 비 또는 천둥을 표현한다.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.4
• /
• pp.512-519
• /
• 1999

Seasonal variation in species composition and abundance of demersal fish in Yongil Bay were determined by analyzing samples collected using an otter trawl from January to October 1991. Of 59 species identified, Repomucenus lunatus, Tridentiger trigonocephalus, Repomucenus heguenini, Ammodytes personatus and Sillago japonica were dominated in abundance. Number of spiecies and biomass were low in winter and high in spring and summer. Species composition did not show spatial variation but showed seasonal variation. Number of spicies, abundance in number of individuals ($630 inds./10^3\;m^2$) and in biomass ($13,131g/10^3\;m^2$), and species diversity (2.00-2.54) of fish in Yongil Bay were higher than those of the coastal waters in the Yellow Sea or in the South Sea of Korea.