• The Korean Journal of Quaternary Research
• /
• v.5 no.1
• /
• pp.15-31
• /
• 1991

A total of 90 surface sediment samples, collected from the continental margin area bordering east and southeast coast of Korea, were subject to the geochemical analyses with the aim of filling the gap in our knowledge of this environment. The analyzed items included the major elements (Al, Fe, Mg, Ca, K, Na, p and Mn), organic carbon, and some trace metals (Ba, Co, Cu, Sr and Zn). The sediment grain-size exerted a predominant influence on the contents of most elements, with the exceptions of Ca, K, Sr and Ba. The Ca and Sr contents, being closely interrelated each other, were mainly controlled by the calcium carbonate content. The K content, on the other hand, appeared to be influenced by both illite and feldspar. The Ba content showed a certain relationship with that of K, suggesting a common source of these two elements; potassium feldspar. The R-mode factor analysis result also reaffirmed the above-mentioned controlling factors on the sediment geochemistry. The grain-size dependency of trace metals obscures their areal distribution pattern from the total contents. However, with the metal/aluminum ratios we could differentiate the subtle difference in the metal enrichment. Hence, sediments of the southern coastal area appear to receive some anthropogenic inputs of metals, though the effect is still negligible.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.49 no.2
• /
• pp.105-109
• /
• 2004

Field studies were conducted in the southeastern Korea ($36^{\circ}$N) on a commerce silt loam soil at paddy field. Seed were manually planted on 16 July 2003. Plants were planted with plant densities of 70${\times}$10 cm (row width x plant spacing), 50 x 10 cm, and 30 ${\times}$10 cm. Two seedlings per hill were taken prior to V3 stage. Fertilizer was applied prior to plant at a rate of 30-30-34 kg (N-$\textrm{P}_2\textrm{O}_5$-$\textrm{K}_2\textrm{O}$) per ha. Experimental design was a randomized complete block in a split plot arrangement with three replications. Yield from different planting densities responded similarly in three soybean cultivars and increased when planting density increased. Somyeongkong showed the highest increasing rate of yield about 26% by 338 g $\textrm{m}^{-2}$ at 30 x l0 cm compared to yield of conventional planting density (70 x 10 cm). Also, the planting density significantly affected pod and seed number and seed weight, but not seed per pod. The tallest plant appeared at 30${\times}$10 cm. The change of leaf area according to days after emergence showed differently in soybean cultivars. The highest and lowest total dry matter production per square meter appeared at 30 x 10 cm and at 70 x 10 cm, respectively. Crop growth rate (CGR) showed greater at R3∼R4 stages compared with V7∼R2 or R2∼R3 growth stages and showed the greatest at 30 x 10 cm in three soybean cultivars. As late planted soybean, there was a significant relation between seed yield and CGR, and leaf area index (LAI) according to planting densities at before and after the flowering stage. Relationship between seed yield and CGR in three planting densities showed a highly significant positive relation ($\textrm{R}^2$=0.757) at R3 to R4 stages, and significant relations ($\textrm{R}^2$=0.505, 0.617) at V7 to R2 and V2 to V3. Also, there was a highly significant positive difference between seed yield and LAI during R3 to R4 and R2 to R3 stages.

• Journal of the Mineralogical Society of Korea
• /
• v.23 no.1
• /
• pp.15-23
• /
• 2010

The absolute clay mineral compositions and regional distribution of the 131 bulk marine surface sediments around the Jeju Island was compared to their relative compositions and distribution using quantitative X-ray diffraction analysis. Average absolute clay mineral composition is illite 15.3% (0.5~40.5%), chlorite 2.6% (0~7.9%), and kaolinite 1% (0~5.6%). Total contents of the clay minerals are very high in the South Sea of Korea, northwestern part and southern offshore of Jeju Island. The average relative composition is illite 70.9% (16.7~89%), chlorite 21.5% (8.4~68.5%), and kaolinite 7.6% (0~29.3%). Relative illite contents are high in the northwestern and southeastern part of study area, and southern part of Jeju Island. Chlorite contents are high in the eastern part of study area and western part of Jeju Island. Kaolinite contents are high in the western and southern part of Jeju Island, and southern offshore of Jeju Isand. Absolute Distribution patterns are very similar to those of fine-grained (from clay to silt) sediment, whereas relative distribution patterns do not show any relationship with those of fine-grained sediment.

• Korean Journal of Plant Taxonomy
• /
• v.46 no.4
• /
• pp.361-370
• /
• 2016

An area comprising Juwangsan National Park and its adjacent mountains (southeastern Korean Peninsula) is a good model system for testing the effects of physical barriers to gene flows in plant populations. We predicted that plant species consisting of isolated populations are genetically more differentiated than those that are rather continuously distributed. Most populations of Sedum polytrichoides occur in four isolated valleys, and we assessed the genetic variability and structures using twelve allozyme loci in ten populations. We also compared the present results to earlier findings pertaining to the two co-occurring herbs Hylotelephium ussuriense (${\equiv}$ Sedum ussuriense) (growing only in the four isolated valleys) and S. kamtschaticum (rather continuously distributed). We found moderate levels of within-population genetic variation in S. polytrichoides ($H_{e}=0.112$). Estimates of among-population divergence in S. polytrichoides were also moderate ($F_{ST}=0.250$) and, as expected, very similar to that of H. ussuriense (0.261) but considerably higher than the variation in S. kamtschaticum (0.165). An analysis of molecular variance (AMOVA) revealed that S. polytrichoides and H. ussuriense had higher percentages of among-valley variation (19% each) than S. kamtschaticum (4%). Most of this variation, as also indicated by the STRUCTURE program, was due to differences in genetic profiles between the two central valleys. We concluded that the genetic differences observed between species (S. kamtschaticum vs. S. polytrichoides and H. ussuriense) are mainly due to differences in their distribution within the study area.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.24 no.3
• /
• pp.58-72
• /
• 2021

In July 2021, UNCTAD classified Korea as a developed country. After the Korean War in the 1950s, economic development was promoted despite difficult conditions, resulting in epoch-making national growth. However, in order to respond to the rapidly changing global economy, it is necessary to continuously study the domestic industrial ecosystem and prepare strategies for continuous change and growth. This study analyzed the industrial ecosystem of the automobile industry where it is possible to obtain transaction data between companies by applying complexity spatial network analysis. For data, 295 corporate data(node data) and 607 transaction data (link data) were used. As a result of checking the spatial distribution by geocoding the address of the company, the automobile industry-related companies were concentrated in the Seoul metropolitan area and the Southeastern(Dongnam) region. The node importance was measured through degree centrality, betweenness centrality, closeness centrality, and eigenvector centrality, and the network structure was confirmed by identifying density, distance, community detection, and assortativity and disassortivity. As a result, among the automakers, Hyundai Motor, Kia Motors, and GM Korea were included in the top 15 in 4 indicators of node centrality. In terms of company location, companies located in the Seoul metropolitan area were included in the top 15. In terms of company size, most of the large companies with more than 1,000 employees were included in the top 15 for degree centrality and betweenness centrality. Regarding closeness centrality and eigenvector centrality, most of the companies with 500 or less employees were included in the top 15, except for automakers. In the structure of the network, the density was 0.01390522 and the average distance was 3.422481. As a result of community detection using the fast greedy algorithm, 11 communities were finally derived.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.24 no.2
• /
• pp.83-94
• /
• 2022

In order to actively prepare to frost damage that occurs in the process of growing crops, the spatial and temporal distribution of frost occurrence in South Korea was derived using frost observation data from 20 regions over the past 21 years (2000~2020). The main products are the number of frost days, first frost day, and last frost day by region. And the climatic trends of these results were identified by performing the Mann-Kendall trend test and Sen's slope estimator. In South Korea, a lot of frost occurs in the inland area to the west of the Taebaek and Sobaek Mountains. Relatively closer to the coastal area, the number of frost days is small, the first frost day is slow, and the last frost day is early. The east coast region has fewer frost days, the first frost day is later, and the last frost day is earlier than the west coast region. The southern sea, the southeastern sea region, and the island region rarely experience frost. As a result of the annual time series trend analysis, although South Korea is a country where climate warming is progressing, there was no trend in reducing the number of frost days and slowing the first frost day, and it was found that the last frost day is delayed by 0.5 days per year.

• Korean Journal of Mineralogy and Petrology
• /
• v.35 no.3
• /
• pp.235-258
• /
• 2022

We interpreted the evolutionary history of the southwestern part of the Pohang Basin, the largest Miocene basin in the southeastern part of the Korean Peninsula, based on the detailed geological mapping and analysis of the geological structures. The southwestern part of the Pohang Basin can be divided into the Bomun Domain in the west and Ocheon Domain in the east by an NNE-trending horst-in-graben. These two domains have different geometries and deformation histories. The Bomun Domain was rarely deformed after the incipient extension of the basin, whereas the Ocheon Domain is an area where continued and overlapped deformations occurred after the basin fill deposition. Therefore, the Bomun Domain provides critical information on the initial extension mode of the Pohang Basin. The subsidence of the Bomun Domain was led by the zigzag-shaped western border fault that consists of NNE-striking normal and NNW-striking dextral strike-slip fault segments. This border fault is connected to the Yeonil Tectonic Line (YTL), a regional dextral principal displacement zone and the westernmost limit of Miocene crustal deformation in SE Korea. Therefore, it is interpreted that the Pohang Basin was initially extended in WNW-ESE direction as a transtensional fault-termination basin resulting from the movement of NNE-striking normal and/or oblique-slip faults formed as right-stepover in the northern termination of the YTL activated since approximately 17-16.5 Ma. As a result, an NNE-trending asymmetric graben or half-graben exhibiting an westward deepening of basin depth was formed in the Bomun Domain. Afterward, crustal extension and deformation were migrated to the east, including the Ocheon Domain.

• Land and Housing Review
• /
• v.15 no.2
• /
• pp.57-71
• /
• 2024

This study aims to develop an evaluation method for solar power facilities considering disaster impacts and to analyse the vulnerabilities of existing facilities. Haenam-gun in Jeollanam-do, where the reassessment of existing facilities is urgent, was selected as the study area. To evaluate the vulnerability from a more objective perspective, principal component analysis and entropy methods were utilised. Seven vulnerability assessment indicators were selected: maximum hourly rainfall, maximum wind speed, number of typhoon occurrence days, number of rainfall days lasting more than five days, maximum daily rainfall, impermeable area ratio, and population density. Among these, maximum hourly rainfall, maximum wind speed, maximum daily rainfall, and number of rainfall days lasting more than five days were found to have the highest weights. The overlay of the derived weights showed that the southeastern regions of Haenam-eup and Bukil-myeon were classified as Grade 1 and 2, whereas the northern regions of Hwawon-myeon, Sani-myeon, and Munnae-myeon were classified as Grade 4 and 5, indicating differences in vulnerability. Of the 2,133 facilities evaluated, 91.1% were classified as Grade 3 or higher, indicating a generally favourable condition. However, there were more Grade 1 facilities than Grade 2, highlighting the need for countermeasures. This study is significant in that it evaluates solar power facilities considering urban disaster resilience and is expected to be used as a basic resource for the installation of new facilities or the management and operation of existing ones.

• Journal of the Korean earth science society
• /
• v.45 no.3
• /
• pp.224-238
• /
• 2024

This study analyzed lineaments and fault-related landforms in Chungcheongnam-do, central Korean Peninsula, based on historical and instrumental records, given its susceptibility to future earthquakes. We extracted 151 lineaments associated with fault-related landforms. In regions with the Dangjin and Yesan faults, lineaments with strikes matching these faults were densely distributed. Conversely, in the Hongseong Fault area, the number of lineaments was smaller, and those with strikes similar to the fault were less discernible. This is likely due to the extensive distribution of alluvium and surface deformation from long-term weathering, erosion, and cultivation, which obscures geomorphic evidence of faults. At five key fault points, we identified fault-related landforms, such as fault saddles, knickpoints in Quaternary alluvium, and linear valleys, along the lineament, which may indicate an actual fault. However, the displacements of the Quaternary layer within the lineaments appear to be influenced more by external factors, such as artificial disturbances (e.g., cultivation) or stream erosion, than by direct fault movement. The differences between the fault-related landforms in this study area and those in the southeastern Korean Peninsula suggest a specific relationship between fault types and their associated landforms.

• Economic and Environmental Geology
• /
• v.50 no.6
• /
• pp.445-466
• /
• 2017

Yeongdong area is located in the contact zone between central southeastern Ogcheon belt and Yeongnam massif, in which Cretaceous Yeongdong basin exists. Therefore, the study area has complex geological environment of various geological age and rock types such as Precambrian metamorphic rocks, age-unknown Ogcheon Supergroup, Paleozoic/Mesozoic sedimentary rocks, Mesozoic igneous rocks and Quaternary alluvial deposits. This study focuses on the link between the various geology and water type, and discussed the source of some major ions and their related water-rock interaction. For this study, the field parameters and ion concentrations for twenty alluvial/weathered and eighty bedrock aquifer wells were used. Statistical analysis indicates that there was no significant differences in groundwater quality between wet and dry seasons. Although various types were observed due to complex geology, 80 to 84 % of samples showed $Ca-HCO_3$ water type. Some wells placed in alluvial/weathered aquifers of Precambrian metamorphic and Jurassic granitic terrains showed somewhat elevated $NO_3$ and Cl concentrations. $Mg-HCO_3$ typed waters prevailed in Cretaceous Yeongdong sedimentary rocks. The deeper wells placed in bedrock aquifers showed complicated water types varying from $Ca-HCO_3$ through $Ca-Cl/SO_4/NO_3$ to $Na-HCO_3$ and Na-Cl type. Groundwater samples with $Na-HCO_3$ or Na-Cl types are generally high in F concentrations, indicating more influences of water-rock interaction within mineralized/hydrothermal alteration zone by Cretaceous porphyry or granites. This study revealed that many deep-seated aquifer had been contaminated by $NO_3$, especially prominent in Jurassic granites area. Based on molar ratios of $HCO_3/Ca$, $HCO_3/Na$, Na/Si, it can be inferred that Ca and $HCO_3$ components of most groundwater in alluvial/weathered aquifer wells were definitely related with dissolution of calcite. On the other hand, Ca and $HCO_3$ in bedrock aquifer seem to be due to dissolution of feldspar besides calcite. However, these molar ratios require other mechanism except simple weathering process causing feldspar to be broken into kaolinite. The origin of $HCO_3$ of some groundwater occurring in Cretaceous Yeongdong sedimentary rock area seems to be from dissolution of dolomite($MgCO_3$) or strontianite($SrCO_3$) as well.