• Journal of Species Research
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• v.11 no.3
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• pp.133-142
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• 2022

In 2020, 24 bacterial strains were isolated from algae, kudzu leaf, mud, pine cone, seashore sand, sea water, soil, tidal flat, and wetland from the Republic of Korea. Isolated bacterial strains were identified based on 16S rRNA gene sequences, and those exhibiting at least 98.7% sequence similarity with known bacterial species, but not reported in Korea, were highlighted as unrecorded species. These isolates were allocated to the phyla Bacteroidetes and Proteobacteria as unrecorded species in Korea. The four Bacteroidetes strains were classified into the families Chitinophagaceae, Flavobacteriaceae, and Sphingobacteriaceae (of the orders Chitinophagales, Flavobacteriales, and Sphingobacteriales, respectively). The 20 Proteobacteria strains belonged to the Aeromonadaceae, Marinobacter, Microbulbiferaceae, Enterobacteriaceae, Erwiniaceae, Morganellaceae, Yersiniaceae, Lysobacteraceae, Halomonadaceae, Moraxellaceae, Pseudomonadaceae, Steroidobacteraceae, Xanthomonadaceae, and Myxococcaceae (of the orders Aeromonadales, Alteromonadales, Cellvibrionales, Enterobacterales, Lysobacterales, Oceanospirillales, Pseudomonadales, Steroidobacter, Xanthomonadales, and Myxococcales). This study focused on the description of 24 unreported bacterial species in Korea in the phyla Bacteroidetes and Proteobacteria belonging to six classes.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.163-172
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• 2007

In this study, fish fauna and stream characteristics were surveyed during October-November 2003 in 31 small streams, which are small sub-tributaries of Geum River. The small streams were classified into 4 types of steep mountainous (SM), mountainous-flatland (MF), flat land (FL), and agricultural watercourse (AW) streams, and their types were categorized by features of stream width, water depth, bottom substrate, riparian vegetation, and landuse patterns. The fishes collected during this survey were identified 4 families and 8 species. Dominant family was Cyprinidae, and the most dominant species was Rhynchocypris oxycephalus with 73% (419 individuals) of the total. Only one species of R. oxycephalus was observed in the all five steep mountainous streams, which was surrounded by 100% forest area and had no point-and non-point pollution sources. The observed frequency of R. oxycephalus (as a relative proportion of species) showed a significant positive correlation (r=0.754, p<0.001, n=31) with the substrate composition of bedrock and boulder, indicating that the species prefer the bedrock and boulder rather than the sand or small pebble. Evidently, all five steep mountainous streams were judged as excellent condition (1st rank) according to the criteria of biological water quality, the Ministry of Environment, Korea. This result was accord with a general tendency of the species in most upper stream of the Koreas streams. One family and one species were found at the steep mountainous types and 4 families 6 species were at the mountainous-flatland. Four families 8 species were found at the flat land, which showed most diverse habitat, and 2 families 2 species were collected agricultural watercourse. These study results of 1st-order streams suggest that R. oxycephalus was considered as one of 1st rank ecological indicator species, and that the dominant area should be protected from various pollutions and disturbances.

• Economic and Environmental Geology
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• v.47 no.6
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• pp.589-599
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• 2014

This study selected optimal sites in Myeongsasimni located in west coast of Korea for stratigraphic research containing extreme climate event during quaternary period by spatio-temporal analyses of changes in sedimentary environment and land use employing 1918 topographic map, 2000 digital terrain map, 1976 and 2012 air photographies. The study area shows no significant changes in topographic characteristics that hilly areas with relatively large variations in elevation are distributed over north and south part of the study area, and sand dues are developed along the coast line. Moreover, flat low lying areas are located at the back side of the sand dues. The movement of surface run off and sediment loads shows two major trends of inland direction flow from back sides of sand dunes and outland direction flow from high terrains inland, and the two flows merge into the stream located in the center of the study area. Two sink with individual area of $0.2km^2$ are observed in Yongjeong-ri and Jaryong-ri which are located in south central part and south part of the study area, respectively. In addition, sea level change simulation reveals that $3.4km^2$ and $3.64km^2$ are inundated with 3 m of sea level rise in 1918 and 2000, respectively, and it would contribute to chase sea level change records preserved in stratigraphy. The inundated areas overlaps well with sink areas where it indicates the low lying areas located in south cental and south part of the study area are identical for sediment accumulation. The areas with minimal human impact on sediment records over last 100 years are $3.51km^2$ distributed over central and south part of the study area with the land use changes of mud and rice field in 1918 to rice field in 2012. The candidate sites of $0.15km^2$ in central part and $0.09km^2$ in south part are identified for preferable locations of geologic record of extreme climate events during quaternary period based on the overlay analysis of optimal sedimentary environment and land use changes.

• Journal of the Korean earth science society
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• v.45 no.3
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• pp.203-213
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• 2024

This study aimed to investigate the seasonal patterns of multiple bar formation in summer and flattening in winter on the macrotidal Sinduri beach in Taean, and to understand the processes their formation and subsequent flattening. Beach profiling has been conducted regularly over the last four years using a VRS-GPS system. Surface sediment samples were collected seasonally along the transectline, and grain size analyses were performed. Tidal current data were acquired using a TIDOS current observation system during both winter and summer. The Sinduri macrotidal beach consists of two geomorphic units: an upper high-gradient beach face and a lower gentler sloped intertidal zone. High berms and beach cusps did not develop on this beach face. The approximately 400-m-wide intertidal zone comprises distinct 2-5 lines of multiple bars. Mean grain sizes of sand bars range from 2.0 to 2.75 phi, corresponding to fine sands. Mean sizes show shoreward coarsening trend. Regular beach-profiling survey revealed that the summer profile has a multi-barred morphology with a maximum of five bar lines, whereas, the winter profile has a non-barred, flat morphology. The non-barred winter profiles likely result from flattening by scour-and-fill processes during winter. The growth of multiple bars in summer is interpreted to be formed by a break-point mechanism associated with moderate waves and the translation of tide levels, rather than the standing wave hypothesis, which is stationary at high tide. The break-point hypothesis for multi-bars is supported by the presence of the largest bar at mean sea-level, shorter bar spacing toward the shore, irregular bar spacing, strong asymmetry of bars, and the 10-30 m shoreward migration of multi-bars.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.175-183
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• 2010

To understand the variation of macro benthos community according to the installation of structure and topographic placement in the shellfish farm on tidal flat, the practical example of the tidal shellfish growing area at Namsung-ri Goheung was observed. The results of the research for the field observation were summarized as follows. (1) The ground gradient of the shellfish farm was very flat below about $1^{\circ}$. The shellfish farm ground took the shape of $\sqcup$ from the shoreline to the place of 150 m seawards, and the shape of $\sqcap$ from there to the low tide line. During ebb tide, the $\sqcup$ shape ground stored the sea water, and the $\sqcap$ shape ground was supposed to act as the effect factor to leak slowly or to prevent the outflow. (2) The oyster shell bag or the type of riprap wall as the boundary in the shellfish farm was classified into five types. The air exposure time and flooding time were 181 and 434 minutes, respectively. (3) In the numerical experiment, the deep-sea water wave coming in the study area had 0.5 m of maximum wave height to show the very stable conditions and the wave direction pattern of S-direction was dominant at Naro great ridge, and SE, SSW and S-direction were distributed strongly around the shellfish farm. (4) By the grain size analysis, the sediment around tidal flat consisted of gravel 0.00~5.81(average 1.70)%, sand 14.15~18.39(average 13.23)%, silt 27.59~47.15(average 30.84)% and clay 35.79~55.73(average 36.19)%, and the sediment type was divided into (g)M(lightly gravelly mud), sM(sandy mud) and gM(gravelly mud) by Folk's diagram. (5) The macro benthos community survey conducted in this site in January, 2010 showed that 1 species of Mollusca, 8 species of Polychaeta and 2 species of Crustacea appeared, and 11 species occupying over 1% of total abundance were dominant.

• Korean Journal of Environment and Ecology
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• v.20 no.1
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• pp.52-69
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• 2006

The flora of vascular plants and the vegetation on the tidal flat was investigated in Jebudo located at Hwaseong city of Gyeonggi-do province from 2004 to 2005. Jebudo has been considered to show difference from the flora which is peculiar to island as it became semi-land by free traffic to mainland with the installation of a road which had enabled entry into the Jebudo in 1991 due to sea-splitting phenomenon. The result of the vascular plants in Jebudo were consissted of 305 taxa; 264 species, 38 varieties and 3 forms of 202 genera of 74 families. As a result of examination by distinctive survey areas within Jebudo, a tidal flat(I) region where the halophyte was being spread has been researched as 7 taxa; 7 species of 6 genera of 5 families. The taxa in Godo-Island(II) was reseached as 50 taxa; 39 species, 11 varieties and 42 genera of 24 families. The taxa in Sand dune area(III) was reseached as 61 taxa; 52 species and 9 varieties of 53 genera of 25 families. The most plant species was reseached in Mt. Tapjae (IV) reaseach area among the reseach areaes 136 taxa; 118 species, 17 varieties and 1 form of 108 genera of 55 families. The taxa in Dangje Mt.(V) was reseached as 119 taxa; 105 species, 13 varieties and 1 form of 95 genera of 45 familes. The taxa in Dongmi Mt. (VI) was reseached as 100 taxa; 85 species and 15 varieties of 83 enera of 43 families. The taxa in Paddy field(VII) was reseached as 120 taxa; 106 species, 13 varieties and 1 form of 86 genera 31 families. Especially, a Crypsinus hastatus community which is a rare plant designated by Korea forest service and a preservation plant designated by the natural environment preservation law (1998) has been discovered at a cliff of Topjae mountain near the ferry located at the northeast side. According to the result of researching halophyte communities which make up the zonation according to the environmental gradient, the communities were being formed in the order of Limonium tetragonum community, Phragmites communis community, Carex scabrifolia community, Triglochin maritimum community and Carex scabrifolia community in accordance with the order of soil particle size with breakwater as their standard.

• Korean Journal of Ichthyology
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• v.32 no.1
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• pp.1-7
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• 2020

Investigations of distribution status and extinction threat evaluation of the Korean endemic species, Iksookimia yongdokensis were undertaken from 2017 to 2018. Among the 22 streams and 97 sampling sites investigated during the study period, samples of I. yongdokensis were collected from 9 streams at 37 sites (from Daejongcheon Stream of Gyeongju-si to Songcheon Stream of Yeongdeok-gun). The appearance of I. yongdokensis was relatively common in streams such as Hyeongsangang River (15 stations), Yeongdeok Oshipcheon Stream (4 stations), Gokgangcheon Stream (4 stations), Chuksancheon Stream (3 stations) and Daejongcheon Stream (3 stations). The main habitat of I. yongdokensis was in pools on flat-land in streams of clean water with slow velocity, and with pebble, gravel and sand bottoms. Previous records of the appearance of I. yongdokensis, indicate they were first seen at seven stations including Jangsacheon Stream, but they were not present in Songcheon Stream. Compared to our results there is evidence as noted for a 38.9% reduction in occupancy within 3 generations (10.5 years), and a decline inhabitat quality. Therefore, I. yongdokensis is now considered vulnerable (VU A2ace) based on the IUCN Red List categories and criteria. The main reasons for the decline were assumed to be dry weathering in the river, the introduction and diffusion of exotic fish species Micropterus salmoides, and river refurbishment project.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.237-243
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• 2000

Agricultural machine is currently operated by man power in the greenhouse, which is oppressively hot and humid, and is for a farmer not to work in comfortable circumstances. In the future, agricultural machine will not have to operate by man power, but it will need do by unmanned power. In order to put into the automatic and unmanned operation of agricultural machine, this system was designed and built to move through the fixed path in the greenhouse. This system was composed of guiders(wires), a limit switch, an operating equipment, its software for automatizing a machine in the greenhouse. The guider was connected between the wall pillars, and the equipment was able to slide over the fixed path made of the guider, by rectilinear and rotational motion. A micro mouse was developed with a stepping motor to calculate on the success rate of its operation with the system As might be expected, this system with the micro mouse was moved the moved the paths with a success rate of 100% on the flat plane surface in our laboratory. However, on the sand plane or the other materials plane, the success rate was not better than 80%. If the micro mouse were well operated, the success rate was would be 100%. Based on the results of this research, this system would be expected to operate well on the path made of a simple wire.

• Journal of Wetlands Research
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• v.9 no.2
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• pp.21-31
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• 2007

Estuarine wetland, where freshwater meets saltwater, is a transitional ecosystem that is valuable ecologically for a variety of reasons, such as feeding and breeding sites for birds, fish, and wildlife. However, research on the spatial distribution and temporal dynamics of estuarine wetlands in Korea is rare. As a fundamental basis for wetland conservation, this study quantified the wetlands in three major estuaries, and evaluated the temporal dynamics of the wetlands since the 1910s. In particular, this study classified the wetland types into mud flat, sand, and emergent-plant types, and estimated the change of each wetland type, using topographic maps produced in the 1910s, 1970s, and 2000s. The wetlands in both the Han and Youngsan River estuaries have declined since the 1910s, but the rate of wetland decline was relatively low before the 1970s, compared to that since the 1970s. The impact of human activities, such as the Youngsan Watershed Comprehensive Development Project and the construction of estuary barrages, has disrupted the estuary cycles and destroyed huge amounts of wetland in the Youngsan estuary. By contrast, estuarine wetlands have been preserved in the small Gahwa estuary, and provide a variety of habitats for plants and wildlife. A special management strategy for wetlands should be established as soon as possible.

• Economic and Environmental Geology
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• v.48 no.5
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• pp.379-390
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• 2015

Multibeam backscatter strength is dependent not only on seafloor sediment facies but also on changed incidence angle due to the actual bottom slope. Therefore, the correction for actual bottom slope should be considered before the analysis of backscatter strength. This paper demonstrates the backscatter correction technique for the actual incidence angle and ensonified area. The target area is a part of the eastern Yellow Sea with water depths of 46~55 m. The area is located between the sand ridges and covered by large dunes with various bottom slopes. The dunes usually have the gentle slopes of about $1{\sim}3^{\circ}$, but show some steep slopes of $5{\sim}15^{\circ}$ on the crest. The backscatter strength values on the crest range from -34 to -23 dB, assuming that the bottom is flat. However, this study shows that the backscatter strength range was somewhat reduced (-32~-25 dB) after correction for actual bottom slope. In addition, the backscatter imagery was significantly improved; high and low backscatter strength values on the crest due to the actual bottom slope were normalized. The results demonstrate that the correction technique in this study is an effective tool for processing backscatter strength.