• Journal of the Korean earth science society
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• v.33 no.6
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• pp.481-496
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• 2012

REE, major and trace elements, and Sr-Nd isotopic ratios of surface sediments around Jeju Island were analyzed for identifying the origin of the sediments. The Chemical Index of Alteration (CIA) between 44.2 to 68.9 (av. 59.4) shows a similarity with the Huanghe sediment. The most sediments found within the study areas show a very similar chondrite-normalized REE pattern that has enriched LREE ($La_{(N)}/Sm_{(N)}$ >3) and small negative Eu anomaly, typically of average shales. The UCC-nornalized REE patterns of the southwestern offshore sediment samples show a very similar pattem with the Changjiang sediment with enriched in most REE and more convex REE pattern than those of the Huanghe and Keum rivers sediments, which indicates that the Changjiang River's suspended sediments have been transported into the western part of Jeju Island. The $^{87}Sr/^{86}Sr$ isotopic ratios vs ${\varepsilon}_{Nd}(0)$ values were thus used as a tracer to discriminate the provenance of sediments in the study area. Based on the discriminated diagram, it clearly showed that most sediments in the western and northwestern part were closely plotted with sediments of the Huanghe River. However, the sediments in the southwestern part near the Changjianf estuary were closely plotted with submerged delta sediments of the Changjiang River. In contrast, the sediment samples of the northeastern part showed discriminative figures from those of the Chinese rivers. It suggests that sediments around Jeju Island must be originated from diverse sources.

• The Korean Journal of Quaternary Research
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• v.23 no.1
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• pp.25-37
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• 2009

Geochemical composition and clay minerals of surface and core sediments around off the Jeju Island were analyzed for identification of sediment origins. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. Smectite is highly concentrated (>8%) in the northwest near the South Yellow Sea and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where fine-grained sediments are discharged from modern and ancient Huanghe River. The relatively high abundance of kaolinite are found in northeastern nearshore area and the southwest near Changjiang estuary. It seems to be supplied from Changjiang River and the southwestern Korea rivers. The sediment accumulation rates measured by $^{210}Pb$ geochronrom mowere 0.20 to 0.54cm/mr or 0.15 to $0.42g/cm^2{\cdot}mr^{-1}$ AOJI, with decreasing rates from the west part to the east part, resulting in the supply of fine-grained suspended sediments from the Changjiang and Huanghe Rivers system. The discrimination diagrams clearly show that the sediments around Jeju Island in the northern East China Sea are ultimately sourced from Chinese rivers, especially from the Huanghe River, whereas the sediment in the northeast part might come from Korean rivers and the Jeju Island.

• Journal of Korean Society of Forest Science
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• v.90 no.6
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• pp.673-682
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• 2001

The objective of this study was to monitor vegetation development process after timber harvesting at (Mt.) Baekwoonsan Seoul National University Forests, Korea. Two monitoring plots were established in 1994 and woody plant were monitored from 1994 to 1999. Vegetation development pattern during last six years(1994-1999) after timber harvesting were as follows; Styrax obassia, Styrax japonica and Lindera erythrocarpa as of the existing tree were competitive species in the first year after clearcut, and Styrax japonica and Lindera erythrocarpa as of sprout tree) and Aralia elata as of seedling were dominant species in the sixth years after clearcut. Species diversity indices of harvested forest interior was decreased at the southwestern slope and increased at the northeastern slope. According to DBH distribution pattern, No. of individuals of Lindera erythrocarpa and Aralia elata showed vigorous growth in the sub-canopy layer and then Styrax japonica, Quercus serrata, Maackia amurensis, Lespedeza maximowixzii, Lindera obtusiloba, Staphylea bumalda, Clero-dendrum trichotomum, Weigela subsessilis, in order showed good growth in the sixth year after clearcut. Lindera erythrocarpa with a reversed J-shaped curve pattern by DBH class will be increased while Aralia elata with a J-shaped curve pattern will be decreased.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.579-587
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• 2018

Chungnam Basin has been known as one of the largest Mesozoic basins in Korea, filled mainly with so-called Daedong Supergroup. The basin has evolved as the Early to Middle Jurassic intra-arc volcano-sedimentary basin developed on top of the Late Triassic to Early Jurassic post-collisional basin in this area, recording evolutionary history of the Mesozoic tectonics in the southwestern Korean Peninsula. This study carries out the geometric interpretations of the Seongjuri syncline and its surroundings in the central part of the Chungnam Basin, based on detailed structural field survey. Based on its doubly-plunging fold geometry, the Seongjuri syncline could be subdivided into the southwestern and northeastern domains. On the down-plunge profiles of the southwestern domain of the Seongjuri syncline as well as the underlying Okma fold, the Okma fault shows typical geometry of a basement-involved reverse fault that propagated up to the sedimentary cover. The profiles illustrate that the Seongjuri syncline occurs in front of the tip of the Okma fault, likely implying its origin as a part of the fault-related fold system. The result of this study will provide better insight into the structural interpretation of the Chungnam Basin, and will further provide useful information for the Mesozoic orgenic events of the southwestern Korean Peninsula.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.493-507
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• 2018

The Wooseok deposit in Jecheon belongs to the Hwanggangri Mineralized Distict of the northeastern Ogcheon Metamorphic Belt. Its geology consists mostly of limestone of the Choseon Supergroup and the Cretaceous Muamsa granite intruded at the eastern area of the deposit. The deposit shows vertical occurrence of skarn and hydrothermal vein ores with W-Mo-Fe and Cu-Pb-Zn mineralization and skarn is developed only at lower levels of the deposit. Skarn minerals are replaced or cut by ore minerals in paragenetic sequence of magnetite-hematite, molybdenite-scheelite-wollframite, and higher abundances of pyrrhotite-chalcopyrite-pyrite-sphalerite-galena. Garnet has chemical compositions of $Ad_{65.9-97.8}Gr_{0.3-32.0}Pyr_{0.9-3.0}$, corresponding to andradite series, and pyroxene compositions are $Hd_{4.5-49.7}Di_{42.3-93.9}Jo_{0.5-7.9}$, prevailing in diopside compositions, both of which suggest oxidized conditions of skarnization. On the FeS-MnS-CdS ternary diagram, FeS contents of sphalerite in vein ores decrease with increasing MnS contents from bottom to top levels, possibly relating to W mineralization in deep and Pb-Zn mineralization in shallow level. Sulfur isotope values of sulfide minerals range from 5.1 to 6.8‰, reflecting magmatic sulfur affected by host rocks. W-Mo skarn and Pb-Zn vein mineralization in the Wooseok deposit were established by spatio-temporal variation of decreasing temperature and oxygen fugacity with increasing sulfur fugacity from bottom to top levels.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1249-1258
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• 2022

Marine debris is defined as a substance that is intentionally or inadvertently left on the shore or is introduced or discharged into the ocean, which has or is likely to have a harmful effect on the marine environments. In this study, the detection of marine debris and the analysis of the amount of change on marine debris were performed using the object detection method for an efficient method of identifying the quantity of marine debris and analyzing the amount of change. The study area is Yuho Mongdol Beach in the northeastern part of Geoje Island, and the amount of change was analyzed through images collected at 15-minute intervals for 32 days from September 12 to October 14, 2022. Marine debris detection using YOLOv5x, a one-stage object detection model, derived the performance of plastic bottles mAP 0.869 and styrofoam buoys mAP 0.862. As a result, marine debris showed a large decrease at 8-day intervals, and it was found that the quantity of Styrofoam buoys was about three times larger and the range of change was also larger.

• Journal of the Daesoon Academy of Sciences
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• v.26
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• pp.215-253
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• 2016

In 2007, according to the records, I made an on-the-spot survey of the place where Doju Cho Jeongsan and his family might have lived in exile in Manchuria and released a paper in which I decided that the site could be the Shuidongchun (village) of Luotongshanzhen in Liuhexian, Jilin Province. Thereafter, sponsored by the Doju Cho Jeongsan's Memorial Project from 2008 to 2013, many times, I carried out the field investigations and researches on Liuhexian, including the visits of the institutions which have the historical documents, in order to find the data related to the participation of him and his family in the anti-Japanese movement. I was, hence, able to reconfirm that the village had been the place of their exile, based on my collected data and the oral reports which the local historians and ethnic Korean elders had provided. In this study, using the historical documents and maps and the oral materials, I made an attempt to prove the historical truth thoroughly once again. First, the existing sources of Doju Cho and his family's settling in Manchuria from March 1909 to 1917, were carefully analyzed which were described in The Jin-gyeong. In doing so, the misspelling of the names and the spatio-temporal errors of the people's activities were corrected. Next, I researched on another town, Shuitungou of Liuhexian in Fengtian Province (in West Gando of Manchuria), which it is known that Doju and his family stayed in, and the Laogushan (mountain), which it is believed that Doju cultivated himself in. Finally, through the attempt, I reached the conclusion that Doju and his family had settled at Shuidongchun (once called Shuidonggou or Shuitongchun) of Luotongshanzhen (once called Datonggou) in Liuhexian, Jilin Province. In the Liuhexian-related documents and maps published in the eras of Republican China and Manchuria, the place name called Shuitungou was not found. However, I discovered a map in the era of Republican China on which Shuitongchun was recorded as Shuidonggou. In addition, considering the administration system of Republic China, tun(屯) and gou(溝) could not be used together in the place names. Accordingly, Shuitungou was more likely misspelled as Korean people in those days mispronounced Shuidonggou. Furthermore, people in China has habitually called the Dagushan(大孤山), located in the north of Gushanzizhen of Liuhexian, as the Laogushan(老孤山). This means that the Korean people who lived in the area then perhaps recorded the mountain as the Nogosan(老姑山), the mountain of the old goddess, according to Korean enunciation, because they had the custom of worshipping the mountain goddess. I tried my best to find the historical documents regarding Doju and his family's anti-Japanese activities to prove the location of exile in which they settled in northeastern China (Manchuria). However, I was not able to reach the initial goal completely due to the shortage of objective evidences, only to leave tasks to be solved. I hope that this study can give a little help to researchers who are interested in this matter.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.407-414
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• 2021

This study investigated the distribution and overwintering of Phanuromyia ricaniae(Hemiptera: Platygastroidea), an egg parasitoid of Ricania sublimata(Hemiptera: Ricaniidea), in order to acquire basic information for biological control. P. ricaniae is distributed in some areas of Gyeonggi, Chungcheong, Jeolla, and Gyeongnam provinces. P. ricaniae is highly prevalent in the southwestern plains, with a tendency to expand to the northeastern area of Korea in line with the dispersal of R. sublimata. The parasitism of P. ricaniae was 1-8% in the field, and the highest in Suncheon, followed by Gurye and Gongju. P. ricaniae overwintered inside the eggs of R. sublimata from September to June of the next year, and transformed into adults in June. The rapid cold-hardiness of P. ricaniae was the highest in the egg state.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.2
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• pp.125-134
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• 2023

The Naedeokri and Nonggeori granites are early Proterozoic granites of the Taebaek-Sangdong area in the northeastern part of the Yeongnam Massif. In this paper, rare earth elements (REEs) concentrations of the minerals in Naedeokri and Nonggeori granites and Rb-Sr mineral isochron age are reported. Except zircon, the constituent minerals such as mica, feldspar, quartz, and tourmaline show LREE-enriched and HREE-depleted REE patterns with relatively large Eu negative anomaly. However, zircon has geochemical characteristic of LREE- and HREE-enriched REE pattern with large Eu positive anomaly. This pattern suggests that zircon should be hydrothermal zircon due to deuteric hydrothermal alteration. In addition, the Rb-Sr mineral age of Naedeokri granite indicates an age value of 1.814±142(2σ) Ma. The Rb-Sr whole rock age including pervious data of Naedeokri and Nogggeori granite indicates an age value of 1,707±74(2σ) Ma. This value is younger than the Sm-Nd isochron of 1.87 Ga, indicating that the Rb-Sr isotope system may be re-homogenized by hydrothermal alteration during the transition from a magmatic to a hydrothermal system.

• Economic and Environmental Geology
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• v.45 no.3
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• pp.217-235
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• 2012

We evaluated the geochemical characteristics and their potential pollution of Asian Dusts in Daejeon, Korea during spring 2007. Compared with the chemical compositions of soils in source area of Asian Dust, those of aerosols in Daejeon were enriched with trace elements (ten to hundred fold), inferring that pollutants from China have affected on local environment in adjoining country such as Korea. Chemical analysis of aerosols during Asian dust showed that fine particles ($PM_{2.5}$) contained high contents of trace elements such as Cr, Cu, Pb, Zn, V, S, As, Cd, Co, Ni, Mo, Sb, Cs, Rb, Th, Sc and Y. In the case of TSP (Total Suspended Particle), Zr, Sr, Ba, Li, Th and U were contained much more than other trace elements. The contents of some elements (i.e. Li, Cs, Co, U, Cr, Ni, Rb, V, Th, Y, Sr and Sc) in aerosols collected in Asian Dust period, which are not likely enriched by air pollutants, were higher (2 - 4.2 fold) than those in Non Asian Dust period, indicating that these elements could be used as indicator elements for determining the occurrence of Asian Dust phenomena (especially, Sr, V, Cr & Li). In the case of Asian Dust coming through the big cities and/or industrial areas of China, the domestic aerosols had higher contents of trace elements (such as S, Cd, Zn, Pb, Cu, Mo and As) than those from Northeastern China via North Korea, indicating that the transportation courses of air mass are very important to determine the pollution degrees. Using the enrichment factors of trace elements in aerosols during Asian Dust and Non Asian Dust, we identified that some elements (i.e. S, Zn, Cu, Pb, As, Mo and Cd) were most problematic in terms of environmental hazard aspects, and these elements could affect adverse effects on human health as well as ecosystem and surface environment (soil and water) through long-lived precipitation.