• 한국해양학회지
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• v.30 no.4
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• pp.332-340
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• 1995

To study stratigraphy of tidal basin deposits, related unconformity and source of late Holocene tidal sediments in Namyang Bay, west coast of Korea, total 8 vibracore sediments have been analyzed. The uppermost stratigraphic sequence of the late Holocene Namyang intertidal deposit overlies three different stratigraphic sequences (1) oxidized reddish brown muddy deposit (Yongduri Member), (2) oxidized yellow deposit (Kanweoldo Formation) and (3) the pre-Cambrian gneiss complex unconformably. Accordingly, three unconformities between those different sequences are recognized. The Namyang tidal deposits (late Holocene) with several meter thickness are mostly coarsening upward sequence suggesting transgressive phase during a continuous rise of sea level. The tidal deposit vibracored down to 4.5 m in depth contains clastic glauconite sands (2% in average) from 2.5 m to the vibracore bottom. These glauconite sands are considered to be transported to the site of Namyang Bay tidal sedimentation from offshore continental shelf of the Yellow Sea along the course of late Holocene sea-level rise.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.3
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• pp.135-141
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• 2001

A paleomagnetic investigation was carried out to analyze magnetostratigraphic information and to evaluate the relationship between paleoenvironment and magnetic properties in sedimentary sequences of piston cores recovered from the abyssal basin of the southwestern Pacific. Pateomagnetic results revealed that the sediments had a stable remanent magnetization and recorded both normal and reversal polarities. The age of sediments was from late Pliocene and Pleistocene determined by matching the polarities with the geomagnetic time scale. The sedimentation rates were in the range of 0.63-1.85 mm/$10^3$ year which were extremely low rates. The results of the paleomagnetic analyses indicated that intervals of the magnetically stable layers as well as high value of susceptibility were significantly affected by the input changes which resulted input of large-quantity materials of relatively stable magnetic carriers.

• Economic and Environmental Geology
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• v.29 no.6
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• pp.689-698
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• 1996

The coal-bearing metapelites from the Hoenam area are interbedded within the Ogcheon Supergroup, which are composed mainly of graphite, quartz, muscovite and associated with trace amount of biotite, chlorite, pyrite, rutile and barite. Although the formation was mined for coal, and the contents of V, U and Mo are a higher grade in coal formations than the host metapelites. The ratios of Al/Na and K/Na in coal formation are very heterogeneous and wide range from 10.28 to 90.91 and from 3.73 to 36.60, respectively. The V content increase with increasing Al and Ba contents, but the U and Mo are not related with other elements. Those are suggested that controlled of mineral compositions in coaly metapelites due to substitution, migration and reequilibrium of elements by regional metamorphism. These coal formation were deposited in basin of marine environments and the REE of these rocks are not influenced with metamorphism and hydrothermal alterations on the basis of Al content versus La, La against Ce, the ratios of La/Ce (0.23 to 0.73) and Th/U (0.03 to 16.6). These rocks also show much variation in $La_N/Yb_N$ (0.53 to 14.19), Th/Yb (0.51 to 6.00) and La/Th (0.15 to 18.92), and their origin is explained by derivation from a mixture of sedimentary and metasedimentary rocks. The wide range in trace and REE element characteristics as Co/Th (0.07 to 3.00), La/Sc (0.04 to 23.48), Sc/Th (0.06 to 7.57), V/Ni (2 to 3319), Cr/V (0.03 to 1.06) and Ni/Co (1.00 to 79.85) of these coaly metapelites argues for inefficient mixing of the various source lithologies during sedimentation.

• Parasites, Hosts and Diseases
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• v.46 no.3
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• pp.133-137
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• 2008

This study was performed to investigate prevalence of clonorchiasis among the inhabitants living in villages along the 4 major rivers, Nakdong-gang (= river), Seomjin-gang, Youngsan-gang, and Guem-gang in southern Korea. From January to December 2006, a total of 24,075 stool samples (1 sample per an inhabitant) were collected in 23 localities and examined by the formalin-ether sedimentation technique. Of the inhabitants examined, 3,441 (14.3%) were found to harbor various types of intestinal parasite eggs, cysts or larvae. Numbers of infected people were 2,661 (11.1%) for Clonorchis sinensis, 431 (1.8%) for heterophyids, 226 (0.9%) for Entamoeba spp., 57 (0.2%) for Giardia lamblia, 30 (0.1%) for Trichuris trichiura, and 18 (0.07%) for echinostomes. Prevalence rates of clonorchiasis according to the river basin were 17.1% in Nakdong-gang, 11.2% in Seomjin-gang, 5.5% in Youngsan-gang and 4.6% in Guem-gang. Of the 2,661 C. sinensis egg-positive cases, 57.7% was male. The present findings suggest that clonorchiasis is still highly prevalent among inhabitants in the riverside areas of southern Korea, and it is necessary to implement a systematic control program in the endemic areas.

• Journal of The Geomorphological Association of Korea
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• v.17 no.1
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• pp.29-38
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• 2010

Oegogae wetland is sub-alpine wetland which is formed in piedmont area in Jirisan National Park. Apparently Oegogae wetland seems to be well-protected wetland. Most alpine wetlands are located in the summit area, but Oegogae wetland is located in piedmont area which is transitional zone between the steep slope and relatively flat valley bottom. Oegogae wetland is active in terms of sedimentation and exceeds 1m in depth. Penetration tests show that composing material is soft such as peat and organic-rich sediment. Basal rock of the basin is gneiss and gneissic schist in general, which is good for the formation of wetland because those rocks are easy to form low permeability layer. Baseflow from the wetland takes control of the most of stream flow during the wet season and this is especially true during the dry season. Precipitation during the wet season increases water content and base flow from the wetland.

• Journal of the Korean Geophysical Society
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• v.7 no.3
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• pp.193-206
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• 2004

Geophysical data including chirp (3 7 kHz) subbottom profile and detailed bathymetry were obtained over three seamounts in the Ogasawara Fracture Zone (OFZ) of the western Pacific, as a part of manganese crust survey onboard R/V Onnuri in 2003. The OFZ is a 150-km-wide, 600-km-long rift zone, which separates the East Mariana and Pigafetta Basin. The OFZ is unique in that it includes many seamounts (e.g., Magellan Seamounts andseamounts on the Dutton Ridge). The sub-seafloor acoustic echoes obtained near the OFZ were classified into following types on the basis of their characteristics: types I-1(pelagic sediment with parallel or subparallel reflectors), I-2 (pelagic sediment with no internal reflectors), and III-1 (reef build-up complex) on summit; types II-1 and III-2 (basement outcrop) on flank rift zone and upper slope, respectively; type III-3 (slump) on the lower slope and embayment between the flank rift zones; types II-2 (debrite) on the base of slope and basin floor; and types II-3 (turbidite or pelagic sediment) and II-4 (turbidite) on the basin floor. The mass-wasting that produced the complex of type II-2 debrite and III-3 slump on the lower slope and basin may have been caused by (1) strong tensional stress in the OFZ which may cause the numerous fissures or basement faults and (2) complex of the faults on the summit and steep upper slope. The variations in the echo type of pelagic sediment in the summit of seamounts may be related with the changes in the depositional and/or erosional environments. Type I-2 pelagic sediment, which is characterized by a thin and intermittent coverage, was probably deposited at a sheltered area when the current was strong, whereas type I-1 pelagic deposit occurred during a stage of progressive sedimentation.

• Economic and Environmental Geology
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• v.45 no.3
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• pp.317-333
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• 2012

The Yeongweol Group is a Lower Paleozoic mixed carbonate-siliciclastic sequence in the Taebaeksan Basin of Korea, and consists of five lithologic formations: Sambangsan, Machari, Wagok, Mungok, and Yeongheung in ascending order. Sequence stratigraphic interpretation of the group indicates that initial flooding in the Yeongweol area of the Taebaeksan Basin resulted in basal siliciclastic-dominated sequences of the Sambangsan Formation during the Middle Cambrian. The accelerated sea-level rise in the late Middle to early Late Cambrian generated a mixed carbonate-siliciclastic slope or deep ramp sequence of shale, grainstone and breccia intercalations, representing the lower part of the Machari Formation. The continued rise of sea level in the Late Cambrian made substantial accommodation space and activated subtidal carbonate factory, forming carbonate-dominated subtidal platform sequence in the middle and upper parts of the Machari Formation. The overlying Wagok Formation might originally be a ramp carbonate sequence of subtidal ribbon carbonates and marls with conglomerates, deposited during the normal rise of relative sea level in the late Late Cambrian. The formation was affected by unstable dolomitization shortly after the deposition during the relative sea-level fall in the latest Cambrian or earliest Ordovician. Subsequently, it was extensively dolomitized under the deep burial diagenetic condition. During the Early Ordovician (Tremadocian), global transgression (viz. Sauk) was continued, and subtidal ramp deposition was sustained in the Yeongweol platform, forming the Mungok Formation. The formation is overlain by the peritidal carbonates of the Yeongheung Formation, and is stacked by cyclic sedimentation during the Early to Middle Ordovician (Arenigian to Caradocian). The lithologic change from subtidal ramp to peritidal facies is preserved at the uppermost part of the Mungok Formation. The transition between Sauk and Tippecanoe sequences is recognized within the middle part of the Yeongheung Formation as a minimum accommodation zone. The global eustatic fall in the earliest Middle Ordovician and the ensuing rise of relative sea level during the Darrwillian to Caradocian produced broadly-prograding peritidal carbonates of shallowing-upward cyclic successions within the Yeongheung Formation. The reconstructed relative sea-level curve of the Yeongweol platform is very similar to that of the Taebaek platform. This reveals that the Yeongweol platform experienced same tectonic movements with the Taebaek platform, and consequently that both platform sequences might be located in a body or somewhere separately in the margin of the North China platform. The significant differences in lithologic and stratigraphic successions imply that the Yeongweol platform was much far from the Taebaek platform and not associated with the Taebaek platform as a single depositional system. The Yeongweol platform was probably located in relatively open shallow marine environments, whereas the Taebaek platform was a part of the restricted embayments. During the late Paleozoic to early Mesozoic amalgamations of the Korean massifs, the Yeongweol platform was probably pushed against the Taebaek platform by the complex movement, forming fragmented platform sequences of the Taebaeksan Basin.

• The Korean Journal of Petroleum Geology
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• v.5 no.1_2 s.6
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• pp.36-47
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• 1997

This study presents multi-variable sequence model for a broader application of sequence concept proposed by Exxon group. The concept of the multi-variable model is based on the fact that internal organization and boundary type of the sequences are determined by three varying factors including 3rd-order cycles of eustasy, and tectonic movement and sediment influx with 2nd-order changes. Instead of Exxon group's systems tracts, this model adopts parasequence sets as the fundamental building blocks of the sequence, because they are descriptive stratigraphic units simply defined by internal stacking pattern, reflecting interactions of accommodation and sediment influx. Seven sequence types which vary in number and type of internal parasequence sets are formulated as associations of four types of accommodation development and three grades of sediment influx. In the southwestern margin of Ulleung Basin, the multi-variable sequence analysis of shelf-slope sequence shows systematic changes in stratal patterns and the numbs, of constituent parasequence sets (i.e. sequence type). These changes are interpreted to reflect temporal and spatial changes in type and rate of tectonic movement and sediment influx, as a result of back-arc opening and closing. During the back-arc opening, rapid subsidence, continuous rise of relative sea level, and high sediment influx gave rise to sequences dominantly of single progradational parasequence set. In the early stage of back-arc closing accompanied by local contractional deformation, different types of sequences contemporaneously formed depending on the spatial changes in tectonically-controlled accommodation and influx rates. During the subsequent slow back-arc subsidence, rise-dominated relative sea-level cycle was coupled with moderate to high sedimentation rate to have resulted in sequences consisting of $2~3$ parasequence sets.

• Economic and Environmental Geology
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• v.22 no.1
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• pp.35-63
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• 1989

Geochemical characteristics of the Guryongsan (Ogcheon) uraniferous black slate show that this is an analogue to the conventional Chattanooga and Alum shales in occurrences. Whereas, its highest enrichment ratio in metals including uranium, among others, is explained by the cyclic sedimentation of the black muds and quartz-rich silts, and the uniform depositional condition with some what higher pH condition compared to the conditions of the known occurrences. The cyclic sedimentation, caused by the periodic open and close of the silled basin, has brought about the flush-out) of the uranium depleted water and the recharge with the new metal-rich sea water, which consequently contributed to the high concentration of metals in mud. The metal-rich marine black muds, which mostly occur in the early to middle Palaeozoic times, is attributed by the geologic conditions which related to the atmospheric oxygen contents, and these are scarcely met in the late Precambrian and/or with the onset of Palaeozoic era in the geologic evolution of the earth.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.277-282
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• 2007

For more accurate and practical design of the residual treatment train at water treatment plants(WTPs), a computational program based on the commercial spreadsheet, Microsoft Excel, was developed. The computational program for the design of a residual treatment train(DRTT) works in three steps which estimate the residual production to be treated, analyze the mass balance, and determine the size of each unit process. Of particular interest in the DRTT program, is provision for a filter backwash recycle system consisting of surge tank and sedimentation basin for more efficient recycling of backwash water. When the DRTT program was applied to the Chungju WTP, the program was very beneficial in avoiding errors which might have occurred during arithmetic calculations and in reducing the time needed to get the output. It is anticipated that the DRTT program could be used for design of new WTPs as well as the rehabilitation of existing ones.