• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.561-569
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• 2013

EOF analysis of tidal residual derived from 2003~2009 tide data was used to identify the spatio-temporal variability. The effect of sea surface air pressures and winds on the tidal residual was also investigated by the correlation analysis. The first mode accounting for 68 % of the total variance represented concurrent sea level rise or fall, and the second mode accounting for 21 % of the total variance explained alternative sea level rise and fall between West Sea coast and both South Sea and East Sea coasts. While northerly and southerly winds dominated the tidal residual in the eastern coast of Yellow Sea, the effect of sea surface air pressures on the tidal residual increased along the coastal regions from South Sea to East Sea.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.381-393
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• 1996

Cretaceous volcanics and volcaniclastic sediments are abundantly distributed in the Haenam area located at the tip of the southwestern part of the Yongdong-Kwangju depression zone. The Cretaceous strata correlated with the Yuchon Group of the Kyongsang Supergroup are divided into three formations: Hwawon Formation, Uhangri Formation and Haenam Formation in ascending order. The stratovolcanic Hwawon Formation is mainly composed of andesite and andesitic pyroclastics. The Uhangri Formation is the lacustrine sedimentary deposit. The Haenam Formation is composed of Hwangsan tuff, Haenam tuff, Yongdang tuff, Seoho tuff, and also Acidic lava, both being formed by a cogenetic acidic volcanism. The topographic circular structure of the Cretaceous strata was controlled by the doming of Jurassic Sani granite. Cretaceous volcanism in the study area is characterized by the two stages of intermediate volcanic activity in Cenomanian to Albian, and acidic volcanic activity in Campanian to Coniacian.

• 한국해양학회지
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• v.21 no.1
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• pp.34-45
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• 1986

A Q-mode factor analysis for 115 surficial bottom sediments on the continental shelf off the southeast coast of Korean Peninsula(the Korea Strait) has been carried out to determine the depositional environments. The first four factors are taken as the "principal" factors, and the results are considered to represent the depositional history and sedimentary processes in relation to the Holocene sea-level changes. The fact implies that the sediments are grouped as outer-shelf relict sand sediments, inner-shelf modern muddy sediments, and finally the palimpsest sediments that are mainly distributed within and around the Korea Trough.

• Explosives and Blasting
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• v.21 no.1
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• pp.69-76
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• 2003

Test blasting has been performed with V-cut to investigate the characteristics. Blasting vibrations were measured at two directions, the proceed direction and side direction. Propagation characteristics were determined by regression analysis; square root scaled distance and cube root scaled distance with maximum charge per delay of the blast. Testing result, The cross point was 62m in the allowable vibration velocity of 3mm/sec and 46m In 5mm/sec. Also, vibration level with measuring point was highest and decayed fastest, adapting to cube root scaled distance, for the proceed direction on ground.

• Journal of the Korean earth science society
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• v.27 no.2
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• pp.221-235
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• 2006

In order to understand the transport mechanism of tidal beach sediments in Deukryang Bay, south coast of Korea, beach profiles, surface sediments, sedimentation rates and hydrodynamic conditions have been investigated. The beach is composed of a steep beach face and gentle low-tide terrace, showing general morphologic characteristics of tide dominated beach. Central beach face of an indented coast becomes flattened in summer, but ridge and runnel system developed in other seasons makes the beach profile rather irregular. These seasonal variations of beach profiles and sedimentation rate indicate that beach sedimentation is mainly controlled by both tide and wave processes. Erosion is prevalent in winter when strong wind wave is dominant, while deposition is dominant in other seasons. However, central beach showed an apparent erosional phase in summer. This is caused by strong waves induced by southerly strong winds occurring ephemerally during the summer. On the other hand, sedimentation rates are -89.2 mm/yr on the central beach and 60.5 mm/yr and 38.2 mm/yr on the sides. This result suggests that sediments are eroded on the central beach and subsequently transported to the both sides. Therefore, the central part of Sumun beach, used as a beach bathing site, will be continuously eroded, if nearby dyke continues to prevent the sediment supply from sources.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.4
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• pp.247-256
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• 2008

For the systematic scientific management of tidal flat sediment in Julpo bay of Korea, this study conducted a survey of particle composition, organic matter(l.L) and heavy metals for three lines ; including F, R and L lines in tidal flat sediment. Particle composition of tidal flat sediments consisted predominantly of clay at F line which was in right angle direction to the coast, whereas R and L lines were located horizontally along the coast and consisted predominantly of silt. Mean grain size values of tidal flat sediments were in the range of 3.7 ${\phi}{\sim}$10.4 ${\phi}$(average 7${\phi}$). The contents of heavy metals observed at R and L lines were lower than those at F line. The correlation analysis among heavy metals, organic matter and particle size was found to have a good interrelationship. For the evaluation of heavy metals pollution, two criteria of US NOAA and KEI(in Korea) were applied Heavy metals pollution level of tidal flat sediments belonged in Non polluted and Moderately polluted groups in US EPA criteria, and its pollution levels sat below ERL in NOAA criteria. The results of heavy metals pollution level obtained by KEI criteria were found to be less than the goal level.

• Journal of Wetlands Research
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• v.6 no.1
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• pp.167-178
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• 2004

The southern tidal flat of Kanghwa Island is one of the biggest flats on the west coast of Korea. Tide is typically a semidiurnal with maximum range of about 10m. The tidal flat receives large amount of sediments from Han River system. Surface sediments for sedimentary analyses were sampled at 83 stations in the study area in August 2003. The surface sediments consisted of five sedimentary facies. Generally, sandy mud sediments dominated in the southern tidal flat of Kanghwa Island, whereas sand sediments dominated in channel and subtidal zones of the western part of Kanghwa Island. The area of sandy mud sediment extended to eastward tidal flat compared to sedimentary facies in August 1997. Sedimentary facies analysis of three core sediments from the tidal flat to the south of the Kangwha Island revealed three sedimentary facies: trough-cross-bedded sand, laminated silt, and bioturbated silt. Distribution of the facies in the cores suggested that sedimentation rates has been generally high in the margin of main tidal channel, especially in the east of the Donggeum Island. Twelve-and-half-hour anchoring survey was carried out for measurements of hydrodynamic parameters at Yeomha channel near Choji Bridge(K1) and channel near Donggeum Island(K2) in June 2003. Residual flows indicated strong ebb-dominated tidal currents. Depth-integrated net suspended sediment loads for one tidal cycle were seaward movement with 309,217.9kg/m and 128,123.1kg/m at station K1 and K2, respectively. The higher value of net suspended sediment loads at station K1 suggested that lots of suspended sediments from Han River deposited in the eastern part of tidal flat.

• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.107-116
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• 2018

In this study, the distribution of sedimentary environment and benthic macro-fauna in habitats and non-habitats of Zostera marina were investigated. The purpose of this study was to obtain basic data about the sedimentary environment and benthic macro-fauna in the habitats and non-habitats of Z. marina. Sand was dominant within habitat environments, whereas the non-habitats were predominantly composed of silt. As a result, the habitats of Z. marina have a different grain size and organic matter content compared to the non-habitats. These differences in the sedimentary environment were expected to influence the species composition of benthic animals. Benthic communities in the habitats of Z. marina showed a higher density and a greater number of species than in the non-habitats. As a result of an ecological index evaluation, the species diversity index (H') was $3.44{\pm}0.10$ for the habitat; the non-habitat was analyzed as $2.34{\pm}0.35$. It was also found that the stability of community in the habitats was higher than that in the non-habitats. The cluster analysis also clearly showed that habitats and non-habitats of Z. marina have distinct characteristics.

• Journal of the Korean Magnetics Society
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• v.7 no.4
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• pp.173-179
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• 1997

Change in phases, microstructures, and magnetic properties by the variation of quench rate and heat treatment were investigated for melt-spun $Fe_{77}Pr_{15}C_8$ ribbons. The amorphization of as-spun ribbons increased as the quench rate increased. As a result, the ribbon quenched at 40 m/s was almost entirely amorphous. Similarly to cast alloys, the primary phase in crystalline ribbons quenched at 10 m/s was $\alpha$-Fe followed by the secondary $Fe_{17}Pr_2C_x$. Crystalline phases were still dominant in the ribbon spun at 20 m/s, but in this case crystallization of $Fe_{17}Pr_2C_x$ was remarkable with a little suppression of $\alpha$-Fe. At 30 m/s an amorphous phase obviously dominated in the as-spun ribbons with small fraction of crystals. Therefore, substantial amount of hard magnetic $Fe_{14}Pr_2C$ was not obtained from the as-spun state but, as in cast alloys, produced only by a solid-state transformation. Within a few minutes fine grains of $Fe_{14}Pr_2C$ were easily obtained at relatively low temperature when the degree of amorphization of as-spun ribbons was higher. The grain size of $Fe_{14}Pr_2C$ was well less than 1${\mu}{\textrm}{m}$. The ribbons quenched at 20 or 30 m/s yielded higher coercivities after heat treatment.

• The Korean Journal of Petroleum Geology
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• v.14 no.1
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• pp.12-20
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• 2008

Oil sands in Canada are representative example of unconventional resources whose reserve estimates are as large as those in Saudi Arabia. Typical reservoir rocks of oil sands consist of channel-related deposits formed in a tide-dominated depositional setting. The tidal deposits are commonly characterized by spatially complicated and heterogeneous properties. Successful engineering methods to develop oil sands require in-depth understanding in the spatial distribution of reservoir properties. Geological model for oil sand reservoir characterization can be built on the basis of comparative studies of ancient and modem analogues. In particular, modern analogue studies become increasingly indispensable, since they provide better understanding in the reservoir-rock forming process and more importantly in the external mechanism responsible for the reservoir heterogeneity. Tide-dominated environment along the west coast of Korea is considered as one of the most excellent modem analogues of oil-sand forming depositional environment. Korean tidal environment provides insights on the origin of mud breccia, facies and stratigraphic architecture which are key issues to the characterization of oil sand reservoirs.