This study evaluated the generalizability of five models to select a suitable approach for landslide susceptibility modeling in data-scarce environments. In total, 418 landslide inventories and 18 ...landslide conditioning factors were analyzed. Multicollinearity and factor optimization were investigated before data modeling, and two experiments were then conducted. In each experiment, five susceptibility maps were produced based on support vector machine (SVM), random forest (RF), weight-of-evidence (WoE), ridge regression (Rid_R), and robust regression (RR) models. The highest accuracy (AUC=0.85) was achieved with the SVM model when either the full or limited landslide inventories were used. Furthermore, the RF and WoE models were severely affected when less landslide samples were used for training. The other models were affected slightly when the training samples were limited.
The objective of this study was to investigate the effectiveness of applying gypsum and rice straw compost on improvements in soil quality during the desalination of previously reclaimed coastal ...tideland soils. The four treatments were control (without amendment), gypsum, rice straw compost, and gypsum+rice straw compost. The experiments were carried out in a completely randomized design with three replicates. Saturated electrical conductivity (ECe) and exchangeable sodium percentage (ESP) values of soils treated with gypsum, or gypsum+rice straw compost, reached the salinity and sodicity classification limits of 4dSm−1 and 15% (US Salinity Laboratory Staff, 1954), respectively, after eight years of leaching experiments. However, despite 10years of leaching experiments, neither the control nor the rice straw compost alone treatment reached the salinity and sodicity classification limits. The addition of gypsum and rice straw compost resulted in a reduction in soil bulk density and a corresponding increase in soil porosity in highly saline-sodic soils (p≤0.05). The results of mean weight diameter (MWD) showed that the application of soil amendments increased MWD significantly (p≤0.05); the highest MWD was observed for the gypsum+rice straw compost treatment and was twice the magnitude of the control.
•Long-term application of gypsum and rice straw compost was affected significantly soil physical indicators.•Addition of gypsum and rice straw compost increased soil aggregate MWD.•Addition of gypsum and rice straw compost decreased both ESP and EC.
The Taebaeksan Basin is located in the mid‐eastern part of the southern Korean Peninsula and tectonically belonged to the Sino‐Korean Craton (SKC). It comprises largely the lower Paleozoic Joseon ...Supergroup and the upper Paleozoic Pyeongan Supergroup which are separated by a disconformity representing a 140 myr−long hiatus. This paper explores the early Paleozoic paleogeographical and tectonic evolution of the Taebaeksan Basin on the basis of updated stratigraphy, trilobite faunal assemblages, and detrital zircon U–Pb ages of the Joseon Supergroup. The Joseon Supergroup is a shallow marine siliciclastic‐carbonate succession ranging in age from the Cambrian Series 2 to Middle Ordovician. The Ongnyeobong Formation is the sole Upper Ordovician volcanic succession documented in the Taebaeksan Basin. It is suggested that in the early Paleozoic the Taebaeksan Basin was a part of an epeiric sea, the Joseon Sea, in east Gondwana. The Joseon Sea was the depositional site for lower Paleozoic successions of the SKC. Early Paleozoic sedimentation in the Joseon Sea commenced during the Cambrian Stage 3 (∼ 520 Ma) and ceased by the end of the Darriwilian (∼ 460 Ma). In the early Paleozoic, the SKC was located at the margin of east Gondwana and was separated from the South China Craton by an oceanic basin with incipient oceanic ridges, the Helan Trough. The spreading oceanic ridges and associated transform faults possibly promoted the uplift of the Joseon Sea, which resulted in cessation of sedimentation and break‐up of the SKC from core Gondwana by the end of the Ordovician.
The Taebaeksan Basin is the site for the Paleozoic strata in Korea and was tectonically a part of the Sino‐Korean Craton. The lower Paleozoic strata of the Sino‐Korean Craton were deposited in an epeiric sea located at the margin of east Gondwana and was separated from the South China Craton by an oceanic basin with incipient oceanic ridges. The spreading oceanic ridges and associated transform faults may have played a major role in the cessation of early Paleozoic sedimentation and break‐up of the Sino‐Korean Craton from core Gondwana by the end of the Ordovician.
Sensitive high-resolution ion microprobe (SHRIMP) zircon U–Pb ages, and whole-rock chemical and isotopic (Sr–Nd) compositions, have been measured on some Middle Triassic plutonic rocks associated ...with post-collisional magmatism in the Gyeonggi Massif (Hongseong, Namyang and Yangpyeong areas), South Korea. Plutonic rocks from the southwest (Hongseong) and central (Yangpyeong) Gyeonggi Massif and central Okcheon Belt (Cheongsan) have ages of ca. 227–226, 231 and 225 Ma, respectively. The plutonic rocks from Hongseong are dominated by granite and quartz syenite, from Namyang by granite, and from Yangpyeong by quartz monzonite to quartz syenite and gabbro. Three rocks from the Gyeonggi Massif have the depletions in Ta–Nb, P and Ti, and enrichment in large ion lithophile elements (LILE) characteristic of plutonic rocks that are subduction-related or derived from an arc-related crustal source. The Hongseong quartz syenite and Yangpyeong quartz monzonite to quartz syenite have features of shoshonitic and high Ba–Sr granitoids, with LREE enrichment and no significant Eu anomaly. The plutonic rocks from the Gyeonggi Massif have high initial
87Sr/
86Sr ratios (0.7083–0.7144) and strongly negative
ε
Nd(
t) (−
20.3 to −
10.4), indicating derivation of the magmas from sources in the middle to upper crust. These high-K calc-alkaline and shoshonitic plutonic rocks formed during periods of relaxation that separated the culminations of post-orogenic uplift/collapse in the transitions from orogenic to anorogenic events after the Early–Middle Triassic continent–continent collision (249–229 Ma) between the North and South China blocks in South Korea. The plutonic rocks of the Gyeonggi Massif support therefore a possible eastern extension of the Early–Middle Triassic Dabie–Sulu collision belt in China.
Comprehensive mineral chemistry, 40Ar–39Ar dating, and whole-rock geochemical data, including Sr–Nd–Pb isotopes, in late Cenozoic (19–6 Ma) alkali basalts (basanite and trachybasalt) from ...Baengnyeong, Pyeongtaek, and Asan in the Korean Peninsula were determined to constrain their mantle source lithologies and spatial distribution. Olivines have high-Ni and low-Ca contents compared with those derived from peridotite sources. In a Sr–Nd isotope diagram, the samples define a mixing array between Indian MORB and the bulk silicate Earth. In Pb–Pb isotope space, they plot closer to the EM1 than to the EM2 end-member. Values of Δ8/4Pb are positive and range from +47.5 to +210.0, whereas Δ7/4Pb values vary from −3.9 to +14.3. On a primitive mantle-normalized multi-element diagram, the basanites show carbonatite-like compositions, with significant negative anomalies in Rb, K, Zr, Hf, and Ti. By contrast, the trachybasalts exhibit positive anomalies in (K), Pb, Sr, and P. Compared with the trachybasalts, the basanites have lower SiO2, and higher FeO* and P2O5 contents for a given MgO content. The REE ratios of the Baengnyeong basanites plot along the modeled trend for carbonated garnet-lherzolite-derived melts. Taken together, these observations suggest that the mantle source of the studied samples comprised three enriched components located at sub-lithospheric depths, namely recycled ancient K–Th-enriched pelagic sediments, eclogite, and carbonates. The mixing proportions of these source materials were different for each volcanic region. Comparison with late Cenozoic intraplate basalts in northeastern Asia indicates no meaningful spatial trend for the EM1 component.
•The Sr–Nd–Pb isotopic systematics define an Indian MORB-EM1 mixing array.•Values of Δ8/4Pb are positive (+48–210), whereas Δ7/4Pb values vary from −4 to +14.•The mantle source contain K–Th-enriched pelagic sediment, eclogite, and carbonate.•There is no meaningful spatial trend for the EM1 component in basalts in NE Asia.
Several isolated lensoidal mafic and serpentinized ultramafic bodies occur in the Hongseong area, South Korea, which is the Korean extension of the Dabie–Sulu collisional belt of China and the ...northern margin of the South China Block. The mafic and ultramafic bodies are important in any interpretation of the Neoproterozoic tectonics of northeast Asia related to the amalgamation and break-up of the Rodinia supercontinent. The Singok, Gwangcheon, and Hongseong ultramafic rocks are significant bodies of ultramafic rock in the Hongseong area. The orthopyroxenes in the Singok harzburgite plot mostly in the forearc peridotite fields of major element classification diagrams. The Singok olivines also classify as forearc peridotite on the basis of their Fo and NiO contents. The spinels of the Singok harzburgite plot within the mantle array on an Al2O3 versus Cr2O3 diagram, and they fall in the ophiolite and supra-subduction zone peridotite (SSZ) fields on several tectonic discrimination diagrams. These data indicate that the Singok harzburgite is a segment of residual mantle that formed in a SSZ tectonic setting before the amalgamation of the Rodinia supercontinent as the Bibong and Baekdong ultramafic rocks in the Hongseong area. The spinels from the Gwangcheon harzburgite and Hongseong dunite have similar geochemical characteristics with those from ultramafic rocks formed in the Lesvos incipient rift. They plot in the mantle array on the Al2O3 versus Cr2O3 diagram and have higher Mg/(Mg+Fe2+) than abyssal peridotites and lower Cr/(Cr+Al) than SSZ and forearc peridotites. These data together with field evidence indicate that the Gwangcheon and Hongseong ultramafic rocks formed in a continental rift tectonic setting during the break-up of the Rodinia supercontinent. These two types of ultramafic rock from the Hongseong area, which formed in different tectonic settings, are correlated well with the two periods of Neoproterozoic magmatic activity along the northern margin of the Yangtze Block which experienced a subduction and continental rifting stages before and after the amalgamation of the Rodinia supercontinent, respectively.
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•There are two types of ultramafic rocks in the Hongseong area, Korea.•The Hongseong area is correlated to the northern margin of the Yangtze Block, China.•One type formed in a SSZ tectonic setting before amalgamation of Rodinia.•The other type formed in a continental rift during breakup of Rodinia.•The preliminary compositional range of spinels formed in a continental rift.
•Our cross-sectional study analyzed the trends in the prevalence of counseling for stress and depression among over two million South Korean adults from 2009 to 2022.•Throughout our observation, ...including the pandemic, there was a significant increase in the prevalence of counseling for stress and depression.•Increasing trends in the prevalence of counseling for stress and depression had a significant surge after the pandemic.•Female sex, urban residence, low income, low self-rated health, low sleeping time, and high COVID-19 worries were linked to a higher prevalence of counseling for stress and depression.
To investigate the long-term trends in counseling for stress and depression using data from a nationwide survey in South Korea. We conducted a nationwide serial, large-scale, cross-sectional, survey-based study using data from 2,903,887 Korean adults from the Korea Community Health Survey, 2009–2022. Our study investigated the trends and risk factors for counseling for stress and depression during the pre-pandemic (2009–2019) and pandemic era (2020–2022). The prevalence of counseling for stress and depression increased across pre-pandemic (counseling for stress: β, 0.217 95 % CI, 0.194 to 0.241; counseling for depression: β, 0.136 0.118 to 0.154) and pandemic periods (β, 0.324 0.287 to 0.360; β, 0.210 0.182 to 0.239, respectively). The prevalence of counseling for stress and depression showed steeper slopes for increasing trends after the outbreak. In addition, subgroups with female sex, urban residence, lower household income, lower self-rated health, shorter sleep time, and higher worries about contracting COVID-19 were the risk factors associated with the increased prevalence of counseling for stress and depression. Our study analyzed the trends in counseling for stress and depression among over two million South Korean adults in 2009–2022, revealing a significant escalation during the pandemic. These findings emphasize the need for mental health policies to support vulnerable groups during the pandemic.
Every year, the Republic of Korea experiences numerous landslides, resulting in property damage and casualties. This study compared the abilities of frequency ratio (FR), analytic hierarchy process ...(AHP), logistic regression (LR), and artificial neural network (ANN) models to produce landslide susceptibility index (LSI) maps for use in predicting possible landslide occurrence and limiting damage. The areas under the relative operating characteristic (ROC) curves for the FR, AHP, LR, and ANN LSI maps were 0.794, 0.789, 0.794, and 0.806, respectively. Thus, the LSI maps developed by all the models had similar accuracy. A cross-tabulation analysis of landslide occurrence against non-occurrence areas showed generally similar overall accuracies of 65.27, 64.35, 65.51, and 68.47 % for the FR, AHP, LR, and ANN models, respectively. A correlation analysis between the models demonstrated that the LR and ANN models had the highest correlation (0.829), whereas the FR and AHP models had the lowest correlation (0.619).
India and South Korea relationship has seen remarkable journey in the last three decades. Apart from rising political and economic weights of both the countries, India and South Korea have also ...emerged as important soft powers in the region. Their soft powers are based on their rich cultural and historical heritages, their democratic traditions and productions of world famous entertainment contents such as movies, dramas, music and so on. The awareness of the cultural connection between the two countries might have been less than expected but both the countries are indeed committed to reach out each other through these connections. Actually soft powers of both the countries are also useful in connecting them bilaterally as well as providing them access to the Southeast Asian countries. This paper tries to look at the role of soft powers of both the countries in their bilateral relations. When the small and middle powers of the region are forced by the US-China contests to work more on their hard powers and alliances/partnerships, the paper argues that a cooperative narrative may emerge in the region through the soft powers reach outs of India and South Korea and their attempts of agenda setting for the region. The paper would also try to explore trajectory of India-South Korea people-to-people connections and flag problems and prospects in the process.
The exhibition, Beyoug Folding Screens 2, which ran from January to April 2023 at the Amorepacific Museum of Art in South Korea, is analysed with a focus on the shift in perspective in presenting ...traditional historical art in museums. The review illustrates how a historical object can be presented in diverse ways, each telling a unique story, while also actively engaging visitors in the exhibition.
