• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.530-543
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• 2023

Societal value of the benefits forests provide has grown significantly, given their pivotal role in mitigating climate change and fostering the shift toward a carbon-neutral society. Due to the economic and public value of forests, which extends far beyond landowners and foresters, the forestry sector mutually interacts with society as a whole. Thus, understanding public perceptions and preferences concerning forests and forest policies from the societal viewpoint is vital for shaping future forest policy decisions. This research delved into evolving perceptions over the past 32 years, using a time-series analysis of data gathered from the 'Public awareness survey on forests'. This survey, conducted seven times between 1991 and 2023 by opinion poll agents, provides insights into changing sentiments. The findings reveal a notable increase in public satisfaction with overall forest policies. Specifically, positive sentiments were observed regarding forest rehabilitation, forest trails, education initiatives, and the establishment and functioning of forest recreation facilities. Conversely, the study highlights areas where public satisfaction remained relatively low, notably in matters concerning the use and conversion of mountainous regions, forest disaster prevention, and international forest cooperation. Additionally, the respondents emphasized the need for heightened attention to forest management, the development of forest roads, and increased efforts in overseas afforestation compared to current initiatives.

• Journal of Korea Water Resources Association
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• v.56 no.10
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• pp.619-629
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• 2023

Recent intensification of climate change has led to an increase in damages caused by droughts. Currently, in Korea, the Standardized Precipitation Index (SPI) is used as a criterion to classify the intensity of droughts. Based on the accumulated precipitation over the past six months (SPI-6), meteorological drought intensities are classified into four categories: concern, caution, alert, and severe. However, there is a limitation in classifying drought intensity solely based on precipitation. To overcome the limitations of the meteorological drought warning criteria based on SPI, this study collected emergency water supply damage data from the National Drought Information Portal (NDIP) to classify drought intensity. Factors of SPI, such as precipitation, and factors used to calculate evapotranspiration, such as temperature and humidity, were indexed using min-max normalization. Coefficients for each factor were determined based on the Genetic Algorithm (GA). The drought intensity based on emergency water supply was used as the dependent variable, and the coefficients of each meteorological factor determined by GA were used as coefficients to derive a new Drought Severity Classification Index (DSCI). After deriving the DSCI, cumulative distribution functions were used to present intensity stage classification boundaries. It is anticipated that using the proposed DSCI in this study will allow for more accurate drought intensity classification than the traditional SPI, supporting decision-making for disaster management personnel.

• Journal of Korea Water Resources Association
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• v.57 no.5
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• pp.311-320
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• 2024

Climate change has been intensifying drought frequency and severity. Such prolonged droughts reduce reservoir levels, thereby exacerbating drought impacts. While previous studies have focused on optimizing reservoir operations using historical data to mitigate these impacts, their scope is limited to analyzing past events, highlighting the need for predictive methods for future droughts. This research introduces a novel approach for predicting minimum inflow at the Seomjingang dam which has experienced significant droughts. This study utilized the Stochastic Analysis Modeling and Simulation (SAMS) 2007 to generate inflow sequences for the same period of observed inflow. Then we simulate reservoir operations to assess firm yield and predict minimum inflow through synthetic inflow analysis. Minimum inflow is defined as the inflow where firm yield is less than 95% of the synthetic inflow in many sequences during periods matching observed inflow. The results for each case indicated the firm yield for the minimum inflow is on average 9.44 m³/s, approximately 1.07 m³/s lower than the observed inflow's firm yield of 10.51 m³/s. The minimum inflow estimation can inform reservoir operation standards, facilitate multi-reservoir system reviews, and assess supplementary capabilities. Estimating minimum inflow emerges as an effective strategy for enhancing water supply reliability and mitigating shortages.

• Journal of Environmental Impact Assessment
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• v.32 no.1
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• pp.49-59
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• 2023

The rapid advance of technology has accelerated global warming. As 50.4 percent of South Korea's population is concentrated in the Seoul Metropolitan Area, which has become a considerable emitter of greenhouse gases, the city's average temperature is expected to increase more rapidly than in other areas in the country. A rise in the average temperature would affect everyday life and urban ecology; thus, appropriate measures to cope with the forthcoming disaster are in need. This study analyzed the changes in plant phenological phases from the past to the present based on temperatures (average temperature of Feb, Mar, April) observed in seven different weather stations nearthe Seoul Metropolitan Area (Ganghwa, Seoul, Suwon, Yangpyeong, Icheon, Incheon, and Paju) and the first flowering dates of Plum tree (Prunus mume), Korean forsythia (Forsythia koreana), Korean rosebay (Rhododendron mucronulatum), Cherry tree (Prunus serrulate), Peach tree (Prunus persica), and Pear tree (Pyrus serotina). Then, RCP (Representative Concentration Pathways) 2.6 and 8.5 scenarios were used to predict the future temperature in the Seoul Metropolitan Area and how it will affect plant phenological phases. Furthermore, the study examined the differences in the flowering dates depending on various strategies to mitigate greenhouse gases. The result showed that the rate of plant phenological change had been accelerated since the 1900s.If emission levels remain unchanged, plants will flower from 18 to 29 earlier than they do now in the Seoul Metropolitan Area, which would be faster than in other areas in the country. This is because the FFD (First Flowering Date), is highly related to temperature changes. The Seoul Metropolitan Area, which has been urbanized more rapidly than any other areas, is predicted to become a temperature warming, forcing the FFDs of the area to occur faster than in the rest of the country. Changes in phenology can lead to ecosystem disruption by causing mismatches in species interacting with each otherin an ecosystem. Therefore, it is necessary to establish strategies against temperature warming and FFD change due to urbanization.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.764-776
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• 2015

This study aims to identify the structure of the plant community, and the ecological succession sere and the change in the forest ecosystem in Jungdaesa-Birobong area, Odaesan National Park_(i._e., located at high altitudes(over 1,000m)). It seeks to offer the basic data for the planning of vegetation management. In order to verify the status of the forest vegetation between Jungdaesa-Birobong, seventeen plots(size is $20m{\times}20m$) were set up as research sites at high altitudes. Importance value, distribution by diameter at breast height(DBH), the growth volume and age of the sample trees, similarity index and species diversity index of each survey plot were analysed. According to the results of DCA(Detrended Correspondence Analysis), one of the multivariate statistical techniques. It was found that the plant communities were classified into five groups: community I_(Quercus mongolica-Tilia amurensis community), community II_(Q. mongolica-Deciduous broad-leaved community), community III_(Q. mongolica-Pinus koraiensis community), community IV_(Abies holophylla-Q. mongolica community) and community V_(A. holophylla-Deciduous broad-leaved community). Community I which is dominated by Quercus mongolica and Deciduous broad-leaved communities is located at an altitude of over 1,300 meters(ranging from 1,335m to 1,495m), the community IV and V which are dominated by Abies holophylla are located at an altitude of under 1,200 meters(ranging from 1,115m to 1,175m) and the community II and III which include the main species of Quercus mongolica, Pinus koraiensis and Abies holophylla are located at an altitude of between 1,160 meters and 1,300 meters. The results showed that Quercus mongolica tends to have a higher importance value of woody species at a higher altitude while Abies holophylla tends to have higher importance value at a lower altitude. For the importance value woody species and -DBH class distribution, the communites I, II and III are expected to continuously maintain the present status. Whereas, for the influence of communities IV and V, Q. mongolica is predicted to be weakened. The age of sample trees was between 85 and 161; the average age was 123. The index of Shannon's Species diversity (H') showed heterogeneity was found among community I_(i._e., located at high altitude) and communities IV and V_(i._e., located at low altitude). As a results of analysing the index of Shannon's Species diversity (H': unit: $400m^2$), community III showed the highest diversity intex with 1.1109 followed by community II with 1.0475, community I with 1.0125, community IV with 0.9918 and community V with 0.8686. This study verified that the index of Shannon's species was significantly different by plant communities. For instance, when comparing the index of Shannon's species diversity in Quercus mongolica communities of this study and that of past relevant research, the value of index is very similar. However, the diversity index for the community which is dominated by Abies holophylla showed lower value when compared to the results from past relevant research.

• Journal of the Korean earth science society
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• v.40 no.6
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• pp.613-623
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• 2019

Over the past decades, daily sea surface temperature (SST) composite data have been produced using periodically and extensively observed satellite SST data, and have been used for a variety of purposes, including climate change monitoring and oceanic and atmospheric forecasting. In this study, we evaluated the accuracy and analyzed the error characteristic of the SST composite data in the sea around the Korean Peninsula for optimal utilization in the regional seas. We evaluated the four types of multi-satellite SST composite data including OSTIA (Operational Sea Surface Temperature and Sea Ice Analysis), OISST (Optimum Interpolation Sea Surface Temperature), CMC (Canadian Meteorological Centre) SST, and MURSST (Multi-scale Ultra-high Resolution Sea Surface Temperature) collected from January 2016 to December 2016 by using in-situ temperature data measured from the Ieodo Ocean Research Station (IORS). Each SST composite data showed biases of the minimum of 0.12℃ (OISST) and the maximum of 0.55℃ (MURSST) and root mean square errors (RMSE) of the minimum of 0.77℃ (CMC SST) and the maximum of 0.96℃ (MURSST) for the in-situ temperature measurements from the IORS. Inter-comparison between the SST composite fields exhibited biases of -0.38-0.38℃ and RMSE of 0.55-0.82℃. The OSTIA and CMC SST data showed the smallest error while the OISST and MURSST data showed the most obvious error. The results of comparing time series by extracting the SST data at the closest point to the IORS showed that there was an apparent seasonal variation not only in the in-situ temperature from the IORS but also in all the SST composite data. In spring, however, SST composite data tended to be overestimated compared to the in-situ temperature observed from the IORS.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.3
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• pp.273-283
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• 2020

Because of climate change, the occurrence of localized and heavy rainfall is increasing. It is important to predict floods in urban areas that have suffered inundation in the past. For flood prediction, not only numerical analysis models but also machine learning-based models can be applied. The LSTM (Long Short-Term Memory) neural network used in this study is appropriate for sequence data, but it demands a lot of data. However, rainfall that causes flooding does not appear every year in a single urban basin, meaning it is difficult to collect enough data for deep learning. Therefore, in addition to the rainfall observed in the study area, the observed rainfall in another urban basin was applied in the predictive model. The LSTM neural network was used for predicting the total overflow, and the result of the SWMM (Storm Water Management Model) was applied as target data. The prediction of the inundation map was performed by using logistic regression; the independent variable was the total overflow and the dependent variable was the presence or absence of flooding in each grid. The dependent variable of logistic regression was collected through the simulation results of a two-dimensional flood model. The input data of the two-dimensional flood model were the overflow at each manhole calculated by the SWMM. According to the LSTM neural network parameters, the prediction results of total overflow were compared. Four predictive models were used in this study depending on the parameter of the LSTM. The average RMSE (Root Mean Square Error) for verification and testing was 1.4279 ㎥/s, 1.0079 ㎥/s for the four LSTM models. The minimum RMSE of the verification and testing was calculated as 1.1655 ㎥/s and 0.8797 ㎥/s. It was confirmed that the total overflow can be predicted similarly to the SWMM simulation results. The prediction of inundation extent was performed by linking the logistic regression with the results of the LSTM neural network, and the maximum area fitness was 97.33 % when more than 0.5 m depth was considered. The methodology presented in this study would be helpful in improving urban flood response based on deep learning methodology.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1181-1186
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• 2013

Due to climate change, the occurrence of abnormal weather conditions has become more frequent, causing damage to vegetable crops grown in Korea. Hot pepper, Chinese cabbage and radish, the three most popular vegetables in Korea, are produced more in the field than in the greenhouse. It has been a trend that the time for field transplanting of seedlings is getting earlier and earlier as the spring temperatures keep rising. Seedlings transplanted too early in the spring take a longer time to resume the normal growth, because they are exposed to suboptimal temperature conditions. This study examined the influence of air temperature during seedling growth on the time required to reach the first fruit maturity and yield of hot pepper. Seedling plants of 'Super Manita' hot pepper was grown in temperatures $2.5^{\circ}C$ and $5.0^{\circ}C$ lower than the optimum temperature (determined by the average of temperatures for the past 5 years). Seedlings were transplanted into round plastic containers (30-cm diam., 45-cm height) and were placed in growth chambers in which the ambient temperature was controlled under natural sunlight. The growth of seedlings under lowered temperatures was reduced compared to the control. The mineral (K, Mg, P, N) concentrations in the leaf tissues were higher when plants were grown with the ambient temperature $2.5^{\circ}C$ lower than the optimum, regardless of changes in other growth parameters. Tissue calcium (Ca) concentration was the highest in the plants grown with optimum temperature. The carbohydrate to nitrogen (C/N) ratio, which was the highest (18.3) in the plants grown with optimum temperature, decreased concomitantly as the ambient temperature was lowered $2.5^{\circ}C$ and $5.0^{\circ}C$. The yield of the early harvested fruits was also reduced as the ambient temperature became lower. The first fruit harvest date for the plants grown with optimum temperature (June 27) was 13 days and 40 days, respectively, earlier than that in plants grown with $2.5^{\circ}C$ (July 10) and $5.0^{\circ}C$ (Aug 6) lower ambient temperatures. The fruit yield per plant for the optimum temperature (724 g) was the greatest compared to those grown with $2.5^{\circ}C$ (446 g) and $5.0^{\circ}C$ (236 g) lower temperatures. The result of this study suggests that the growers should be cautioned not to transplant their hot pepper seedlings too early into the field, since it may delay the time of first harvest eventually reducing total fruit yield.

• Journal of the Korean earth science society
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• v.41 no.5
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• pp.504-519
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• 2020

Oceanic fronts, which are areas where sea water with different properties meet in the ocean, play an important role in controlling weather and climate change through air-sea interactions and marine dynamics such as heat and momentum exchange and processes by which properties of sea water are mixed. Such oceanic fronts have long been described in secondary school textbooks with the term 'Jokyung water zone (JWC hereafter) or oceanic front', meaning areas where the different currents met, and were related to fishing grounds in the East Sea. However, higher education materials and marine scientists have not used this term for the past few decades; therefore, the appropriateness of the term needs to be analyzed to remove any misconceptions presented. This study analyzed 11 secondary school textbooks (5 middle school textbooks and 6 high school textbooks) based on the revised 2015 curriculum. A survey of 30 secondary school science teachers was also conducted to analyze their awareness of the problems. An analysis of the textbook contents related to the JWC and fishing grounds found several errors and misconceptions that did not correspond with scientific facts. Although the textbooks mainly uses the concept of the JWC to represent the meeting of cold and warm currents, it would be reasonable to replace it with the more comprehensive term 'oceanic front', which would indicate an area where different properties of sea water-such as its temperature, salinity, density, and velocity-interact. In the textbooks, seasonal changes in the fishing grounds are linked to seasonal changes in the North Korean Cold Current (NKCC), which moves southwards in winter and northwards in summer; this is the complete opposite of previous scientific knowledge, which describes it strengthening in summer. Fishing grounds are not limited to narrow coastal zones; they are widespread throughout the East Sea. The results of the survey of teachers demonstrated that this misconception has persisted for decades. This study emphasized the importance of using scientific knowledge to correct misconceptions related to the JWC, fishing grounds, and the NKCC and addressed the importance of transferring procedures to the curriculum. It is expected that the conclusions of this study will have an important role on textbook revision and teacher education in the future.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.194-199
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• 2020

Unlike in the past, the world is facing water shortages due to climate change and difficulties in simultaneously managing the risks of flooding. The Four Major Rivers project was carried out with the aim of realizing a powerful nation of water by managing water resources and fostering the water industry, and the construction period was relatively short compared to the unprecedented scale. Therefore, the prediction and analysis of how the river environment changes after the Four Major Rivers Project is insufficient. Currently, part of the construction section of the Four Major Rivers Project is caused by repeated erosion and sedimentation due to the effects of sandification caused by large dredging and flood-time reservoirs, and the head erosion of the tributaries occurs. In order to solve these problems, the riverbed maintenance work was installed, but it resulted in erosion of both sides of the river and the development of new approaches and techniques to keep the river bed stable, such as erosion and excessive sedimentation, is required. The water agent plays a role of securing a certain depth of water for the main stream by concentrating the flow so much in the center and preventing levee erosion by controlling the flow direction and flow velocity. In addition, Groyne products provide various ecological environments by forming a natural form of riverbeds by inducing local erosion and deposition in addition to the protection functions of the river bank and embankment. Therefore, after reviewing the method of determining the shape of the Groyne structure currently in use by utilizing the mobile limit flow rate and marginal reflux force, a new Critical Movement Velocity(${\bar{U}}_d$) and a new resistance coefficient formula considering the mathematical factors applicable to the actual domestic stream were developed and the measures applicable to Groyne installation were proposed.