• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.435-444
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• 2023

Suitable environmental conditions in Saemangeum frequently favor phytoplankton growth. There have been occurrences of sudden phytoplankton blooms, surpassing the algae management standards. A model was designed to prevent such blooms using scientific predictive techniques to forecast and regulate the possibility of phytoplankton blooms. We propose effective and efficient algae control measures concerning every phytoplankton species optimized through the policy control of nutrients (DIN, PO4-P) from rivers and controlling lake salinity using gate operations. The probability of phytoplankton blooms was initially forecast using an artificial neural network algorithm based on observations. The model's Kappa number fluctuated from 0.7889 to 1.0000, indicating good to excellent predictive power. The Garson algorithm was then utilized to assess the significance of explanatory variables for every species. Meanwhile, the probability of phytoplankton blooms was anticipated depending on the DIN and salinity value changes. Therefore, the model predicted the precise DIN and salinity concentrations to inhibit phytoplankton blooms for each species. Hence, the green algae model can create effective proactive measures to avoid future phytoplankton blooms in enormous artificial lakes.

• Journal of the Korean GEO-environmental Society
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• v.24 no.8
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• pp.5-11
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• 2023

Due to frequent occurrences of concentrated heavy rainfall caused by abnormal climate conditions in recent years, collapses of steep slopes have been occurring frequently due to surface erosion and increased pore water pressure. Various methods are being applied to prevent slope collapses, such as increasing the resistance to movement and reducing pore water pressure. Research on these methods has been consistently conducted as they provide an efficient response to slope collapses by satisfying both the conditions of resistance to movement and pore water pressure simultaneously. Therefore, in this study, we propose an upward slope reinforcement method by burying drainage materials with an upward slope inclination, instead of the conventional horizontal application. This approach aims to satisfy both slope reinforcement and drainage functions effectively, offering a comprehensive solution for slope stabilization. Furthermore, to determine the optimal burial angle that exhibits the most effective reinforcement and drainage effects of the proposed method, we investigated the reinforcement and drainage effects under conditions where the horizontal drainage materials were set at angles ranging from 0° to 60° in increments of 10° on a representative cross-section. Additionally, indoor model experiments were conducted under the conditions of 40°, which showed the most outstanding drainage effect, and 20°, which exhibited the highest safety factor, to validate the numerical analysis results. The results showed that the burial angle of 40° exhibits a relatively higher drainage effect as with the numerical analysis results, while the angle of 20° results in inadequate drainage and observed slope collapse.

• Journal of The Geomorphological Association of Korea
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• v.27 no.1
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• pp.61-89
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• 2020

The objective of this study is to characterize landslide susceptibility depending on various geo-environmental variables as well as to compare the Frequency Ratio (FR) and Evidential Belief Function (EBF) methods for landslide susceptibility analysis of rainfall-induced landslides. In 2013, a total of 259 landslides occurred in Chuncheon, Gangwon Province, South Korea, due to heavy rainfall events with a total cumulative rainfall of 296~721mm in 106~231 hours duration. Landslides data were mapped with better accuracy using the geographic information system (ArcGIS 10.6 version) based on the historic landslide records in Chuncheon from the National Disaster Management System (NDMS), the 2013 landslide investigation report, orthographic images, and aerial photographs. Then the landslides were randomly split into a testing dataset (70%; 181 landslides) and validation dataset (30%; 78 landslides). First, geo-environmental variables were analyzed by using FR and EBF functions for the full data. The most significant factors related to landslides were altitude (100~200m), slope (15~25°), concave plan curvature, high SPI, young timber age, loose timber density, small timber diameter, artificial forests, coniferous forests, soil depth (50~100cm), very well-drained area, sandy loam soil and so on. Second, the landslide susceptibility index was calculated by using selected geo-environmental variables. The model fit and prediction performance were evaluated using the Receiver Operating Characteristic (ROC) curve and the Area Under Curve (AUC) methods. The AUC values of both model fit and prediction performance were 80.5% and 76.3% for FR and 76.6% and 74.9% for EBF respectively. However, the landslide susceptibility index, with classes of 'very high' and 'high', was detected by 73.1% of landslides in the EBF model rather than the FR model (66.7%). Therefore, the EBF can be a promising method for spatial prediction of landslide occurrence, while the FR is still a powerful method for the landslide susceptibility mapping.

• Korean Journal of Construction Engineering and Management
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• v.24 no.6
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• pp.74-80
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• 2023

This study examines the characteristics of architectural review opinions as unstructured data, focusing on the most challenging risk for developers of small and medium-sized apartment projects in response to the increasing number of single-person households in Korea. Using multidimensional analysis methods, the study analyzes the review opinions of 25 projects in B City. Correspondence analysis and MDS (Multidimensional Scale) analysis show that, consistent with prior research, the keywords related to 'structure' and 'planning' dominate architectural review opinions in B City. While the MDS model's stress is very poor at 34.4%, correspondence analysis reveals that this is due to the characteristics of unstructured data in architectural reviews. In addition, the non-structured data analyzed in this study, such as architectural review opinions, exhibited a probability distribution with low kurtosis and high skewness, as they involved various combinations and occurrences of data depending on the discretion of the review committee members and the specific formats of different local governments. This often led to the emergence of keywords that differed significantly from commonly mentioned terms. Although the study has some limitations, it provides a foundation for future detailed analysis by identifying the characteristics of architectural review opinions as unstructured data.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.245-257
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• 2023

The representative crop in the Republic of Korea, rice, is cultivated over extensive areas every year, which resulting in reduced resistance to pests and diseases. One of the major rice diseases, rice blast disease, can lead to a significant decrease in yields when it occurs on a large scale, necessitating early detection and effective control of rice blast disease. Drone-based crop monitoring techniques are valuable for detecting abnormal growth, but frequent image capture for potential rice blast disease occurrences can consume significant labor and resources. The purpose of this study is to early detect rice blast disease using remote sensing data, such as drone and satellite images, along with weather data. Satellite images was helpful in identifying rice cultivation fields. Effective detection of paddy fields was achieved by utilizing vegetation and water indices. Subsequently, air temperature, relative humidity, and number of rainy days were used to calculate the risk of rice blast disease occurrence. An increase in the risk of disease occurrence implies a higher likelihood of disease development, and drone measurements perform at this time. Spectral reflectance changes in the red and near-infrared wavelength regions were observed at the locations where rice blast disease occurred. Clusters with low vegetation index values were observed at locations where rice blast disease occurred, and the time series data for drone images allowed for tracking the spread of the disease from these points. Finally, drone images captured before harvesting was used to generate spatial information on the incidence of rice blast disease in each field.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1235-1243
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• 2023

This study proposes the detection algorithm for the cold water mass (CWM) along the eastern coast of the Korean Peninsula using sea surface temperature (SST) data provided by the Korea Institute of Ocean Science and Technology (KIOST). Considering the occurrence and distribution of the CWM, the eastern coast of the Korean Peninsula is classified into 3 regions("Goseong-Uljin", "Samcheok-Guryongpo", "Pohang-Gijang"), and the K-means clustering is first applied to SST field of each region. Three groups, K-means clusters are used to determine CWM through applying a double threshold filter predetermined using the standard deviation and the difference of average SST for the 3 groups. The estimated sea area is judged by the CWM if the standard deviation in the sea area is 0.6℃ or higher and the average water temperature difference is 2℃ or higher. As a result of the CWM detection in 2022, the number of CWM occurrences in "Pohang-Gijang" was the most frequent on 77 days and performance indicators of the confusion matrix were calculated for quantitative evaluation. The accuracy of the three regions was 0.83 or higher, and the F1 score recorded a maximum of 0.95 in "Pohang-Gijang". The detection algorithm proposed in this study has been applied to the KIOST SST system providing a CWM map by email.

• Journal of Korean Society of Rural Planning
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• v.30 no.1
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• pp.15-31
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• 2024

The study primarily aims to examine the characteristics of the transition from natural landscape to modern agricultural landscape on the Daesan plain in Dong-myeon, Changwon-si, in the lower reaches of the Nakdong River. The periods covered in the transition include the late Joseon Dynasty, the early Japanese colonial period, and the late Japanese colonial period. The study concluded the following: It was found that the Daesan Plain used to function as a hydrophilic landscape before it formed into a rural landscape. This is characterized by the various water resources in the Plain, primarily by the Nakdong River, with its back marsh tributaries, the Junam Reservoir and Jucheon. To achieve its recent form, the Daesan Plain was subjected to human trial and error. Through installation of irrigation facilities such as embankments and sluices, the irregularly-shaped wetlands were transformed into large-scale farmlands while the same irrigation facilities underwent constant renovation to permanently stabilize the rural landscape. These processes of transformation were similarly a product of typical colonial expropriation. During the Japanese colonial period, Japanese capitalists initiated the construction of private farms which led to the national land development policy by the Governor-General of Korea. These landscape changes are indicative of resource capitalism depicted by the expansion of agricultural production value by the application of resource capital to undeveloped natural space for economic viability. As a result, the hierarchical structure was magnified resulting to the exacerbation of community and economic structural imbalances which presents an alternative yet related perspective to the evolution of landscapes during the Japanese colonial period. In addition, considering Daesan Plain's vulnerability to changing weather conditions, natural processes have also been a factor to its landscape transformation. Such occurrences endanger the sustainability of the area as when floods inundate cultivated lands and render them unstable, endangering residents, as well as the harvests. In conclusion, the Daesan Plain originally took the form of a hydrophilic landscape and started significantly evolving into a rural landscape since the Japanese colonial period. Human-induced land development and geophysical processes significantly impacted this transformation which also exemplifies the several ways of how undeveloped natural landscapes turn into mechanized and capitalized rural landscapes by colonial resource capitalism and development policies.

• Journal of Korea Water Resources Association
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• v.57 no.5
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• pp.359-369
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• 2024

Korea prepares for potential floods by designating June 21st to September 20th as the flood season. However, many dams in Korea have suffered from extreme floods caused by different climate patterns, as in the case of the longest consecutive rain of 54 days in the 2020's flood season. In this context, various studies have tried to develop novel methodologies to reduce flood damage, but no study has ever dealt with the validity of the current statutory flood season thus far. This study first checked the validity of the current flood season through the observation data in the 21st century and proved that the current flood season does not consider the effects of increasing precipitation trends and the changing regional rainfall characteristics. In order to deal with these limitations, this study suggested seven new alternative flood seasons in the research area. The rigid reservoir operation method (ROM) was used for reservoir simulation, and the long short-term memory (LSTM) model was used to derive predicted inflow. Finally, all alternatives were evaluated based on whether if they exceeded the design discharge of the dam and the design flood of the river. As a result, the floods in the shifted period were reduced by 0.068% and 0.33% in terms of frequency and duration, and the magnitude also decreased by 24.6%, respectively. During this period, the second evaluation method also demonstrated that flood decreased from four to two occurrences. As the result of this study, the authors expect a formal reassessment of the flood season to take place, which will ultimately lead to the preemptive flood response to changing precipitation patterns.

• Journal of Korean Medicine for Obesity Research
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• v.24 no.1
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• pp.94-101
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• 2024

Herbal medicine (HM)-containing Ephedra Sinica (ES) has been associated with false-positive amphetamine immunoassay (FP IA) results. This study retrospectively evaluated the effects of dose, duration, and withdrawal instructions on FP IA and the safety of HM-containing ES at a clinic in Seoul from 2022 to 2023. The study included 6 patients in the FP IA group and 5 patients in the withdrawal instruction negative (Neg) group. The pre-test ephedrine alkaloids dose in the FP IA group was 95.17±31.90 mg, compared with 88.6±20.43 mg in the Neg group. The FP IA group had taken HM for 226.67±152.87 days before testing, and testing was performed while taking HM. In contrast, the Neg group had taken HM for 147.6±23.49 days and had 5.4±1.50 days of withdrawal period before the test following instructions of Korean medicine doctors. All adverse events (AEs) were moderate in severity, and the number of occurrences was similar: 5 in the FP IA group and 7 in the Neg group. AEs included constipation, insomnia (3 cases each), and palpitations (2 cases). The results of this study show that ES-induced FP IA can be resolved with withdrawal instructions and ES can be safely prescribed and administered by Korean medicine doctors. Further studies are needed to determine how to prevent FP IA after taking ES.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.519-529
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• 2023

The occurrence of eggs and adults of Pochazia shantungensis, Lycorma delicatula, and Lymantria dispar was investigated in 11 cities in the Chungcheongbukdo region. The results showed that the overwintering eggs of P. shantungensis occurred in 24.2% of the region in 2021 and 22.1% in 2022, while adults occurred in 25.2% in 2021 and 24.3% in 2022, indicating the highest occurrence among the pests studied. The occurrence of overwintering eggs of L. delicatula was relatively low, with 2.6% of the region affected in 2021 and 1.9% in 2022. Adult L. delicatula occurred in 3.2% of the region in 2021 and 3.6% in 2022. Overwintering eggs of L. dispar occurred in 4.1% of the area in 2021 and 1.7% in 2022, showing a decreasing tendency compared to the previous year, and their occurrence was only low to middle in terms of the degree of occurrence. Adult L. dispar occurred in 4.6% of the region in 2021 and 2.7% in 2022, showing occurrences that were insignificant compared to L. delicatula. According to a survey of host preferences, both the wintering eggs and adults of P. shantungensis were found in apples and peaches between 2021 and 2022. In both 2021-2022, adult L. delicatula had a high incidence in peaches, apples, and grapes, and winter eggs were the highest in grapes. However, the incidence in apples and peaches was low. A high incidence density of L. dispar moth adults and overwintering eggs was found in apples in both 2021 and 2022.