• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.1
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• pp.27-36
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• 2006

Most of domestic multipurpose dams were basin area to be large, therefore, soil loss were occurred by downpour in the rainy season, They have caused to accumulate sediments on the river and dam reservoir that brought the decrease of storage volume and difficulties of the quality management of water. Until now, the measurement cycle of sediments surveying was long and it was designed to use surveying the degree of sediments, Thus there were many difficult things to secure accuracy. In this study, it was intended to analyze the origin position tracing of sediments and the movement route, for this purpose, aerial LiDAR technology was applied to precise sediments surveying. The amount and location of soil loss were evaluated by classified properties of soil, land-cover, and topographical conditions in detail. Therefore, the reliance could be maintained in analyzing the route of soil loss by extracting the flow within a watercourse and using the advanced accurate DEM.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1500-1506
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• 2015

The headcut erosion at the confluence section of a mainstream and tributary can migrate up the tributary streams, and rapid degradation can threaten the stability of hydraulic structures installed in the channel. Therefore, quantitative analysis for the development and mechanism of headcut erosion is needed to prevent damage due to the headcut. In this study, hydraulic experiments for headcut erosion in the channel with noncohesive materials were performed and the knickpoint movement and final bed slope change were analyzed based on the different hydraulic conditions. As a result, the knickpoint movement was 1.5 times faster when the difference in velocity between the upstream and downstream sections was 2.5 times greater and the central part of the cross-section was eroded and collapsed earlier than the left and right sides. The movement length of headcut erosion was longer and the final bed slope was milder as the velocity difference between the upstream and downstream sections was increased. This study showed that a correlation between the knickpoint movement and bed slope change by headcut erosion and the water level difference of upstream and downstream sections was not constant compared to the velocity difference.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.1
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• pp.9-20
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• 1991

The characteristics of the unconsolidated sediment in Gwangyang bay was analyzed from the core samples. The porosity of the sediment showed irregular variation with respect to the sedimentation depth, which indicated that sediment weight-induced consolidation was not significant. Numerical analysis for the mechanical and hydraulic behavior of the unconsolidated sediment due to the tidal sea level change was processed. Because of the delayed excessive pore pressure change in the very low permeable mud medium, the magnitude of the excessive pore pressure for the duration of the minimum sea level exceeded the total stress from the sea water weight, which resulted in the negative (tensional) effective stress below the top surface. The in-situ effective stress, obtained by superposing the tensional effective stress on the solid weight-induced compressive stress, was remained to be tensile (quick-sand condition) near the top surface of the mud deposit. The occurrence of the quirk-sand condition provided a theoretical evidence for the insignificant consolidation and the irregular porosity variation of the sediment. When the sand is distributed on the top surface of the mud layer, the quick-sand condition occurred below the sandy mud layer and the downward movement of sand particles was facilitated.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.1-8
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• 2009

This study used a mesocosm which presumes movement of the nutrient (especially $PO_{4^-}P$) in the wetland. After setting up the mesocosm inside the wetland and adding the $PO_{4^-}P$, observed the movement of the $PO_{4^-}P$ every hour. We analyzed the variables which had the possibility of affecting $PO_{4^-}P$ concentration in the wetland-flora, absorbing rate of algae, settling rate, release rate. Immediately after adding $PO_{4^-}P$, the concentration of the TP in water column at each mesocosm was 0.48, 12.4, 20.4, $23.6\;mg\;L^{-1}$, after 21 days they were 0.6, 1.92, 6.97 and $6.94\;mg\;L^{-1}$ respectively. The concentration of the TP in water column at the mesocosm decreased on average 73.7%. The concentration of the $PO_{4^-}P$ inside reed, algae and sediment in the mesocosm was increased from $0.73mg\;gDW^{-1}$, $3.81mg\;gDW^{-1}$, $466.1mg\;kg^{-1}$ to $0.83mg\;gDW^{-1}$, $4.57mg\;gDW^{-1}$ and $813.3mg\;kg^{-1}$ respectively. Algae is more sensitive than reeds in absorption of the nutrient. TP removal by settling was highest. Budgeting of TP indicated that P moved from particulates in the water column to sediment and algae. Immediately after adding $PO_{4^-}P$, water column (24.2%) and sediment (49.0%) dominated TP storage, with algae (10.3%) and reed (16.4%) holding smaller proportions of TP. After 21 days, Sediment (59.0%) and algae (17.9%) dominated TP storage, with water column (7.1%) and reed (15.8%) holding smaller proportions of TP. Estimation of phosphate movement using mesocosms is an appropriate method because wetlands have many controlling factors. Analysed data can be compared to background data for wetland construction and management.

• 한국석유지질학회:학술대회논문집
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• spring
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• pp.29-37
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• 1998

The sedimentary succession on the northern coast of Jindo and the adjacent area comprises the thinly bedded, fine-grained deposits of an epiclastic sandstone, siltstone, black shale/mudstone, and cherty mudstone (ca. 200m in vertical thickness), which are interpreted as the finely stratified turbidites mainly by density underflow-induced currents. Most deposits can be divided into eight facies: thin-bedded, ash-rich massive sandstone layer (mS), graded and laminated mudstone layer (glM), graded mudstone layer with ripple lamination (rM), laminated and graded siltstone layer (lgZ), finely laminated black shale layer (IBS), structureless mudstone layer (mM), thin-bedded cherty mudstone layer (lCM), and contorted and laminated mudstone layer (dlM), The thin-bedded, ash-rich sandstone facies is interpreted to be deposited from high-density turbid underflows during a relatively large flooding. Most thinly bedded mudstone facies would be deposited from low-density turbid underflows (turbidity currents) with some different hydrodynamic condition and sediment concentration during the high discharge of river water. Whereas the structureless mudstone facies may result from raining down of suspended sediment intermittently supplied by overflows and interflows. From the entire succession, graded and laminated mudstone layers interbedded with thin-bedded, ash-rich massive sandstone are dominant in the lower part of the succession, and graded mudstone layers with ripple lamination ripple lamination occur mainly in the middle part of it. On the other hand, iaminated/raded siltstone and contorted/laminated mudstone layers prevail in the upper part. The transition of facies association is suggestive of the continuous change of main depositional setting from basin plain to lower slope, which could be due to the movement of depocenter by the increase of sediment supply (volcanic activity).

• The Korean Journal of Quaternary Research
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• v.5 no.1
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• pp.33-45
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• 1991

Sand bars associated with strong tidal currents are well developed in the subtidal zone near the Kokunsan islands. Tidal currents measured at sand bar in the area show an asymmetry in magnitude between flood and ebb currents. At the southern flank of the sand bar the currents are flood-dominant whereas the currents are ebb-dominant at the northern flank. The asymmetry is more distinctive as the currents become stronger during spring tide. Moreover, the flood-dominance along the southern flank is stronger than the ebb-dominance along the northern flank. Thus the flood current is more affective to the sand bar. The sandy bottom sediment is mostly transported as bedload by the tidal currents. The magnitude asymmetry of the tidal currents results in a net sediment movement in one direction. The direction is onshore in the south and offshore in the north, which may result in a net counterlookwise rotation of the sands around the sand bar. However, the sand bar may migrate towards onshore due to the more affective flood current in the south. The irregular V-shaped outline of the sand bar in the south also seem to reflect the strong effect of flood current.

• Journal of the Korean association of regional geographers
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• v.10 no.3
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• pp.667-681
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• 2004

This research is aimed to investigate the relationship of the effective wind velocity and the morphological change in coastal dune at Sindu-ri in Korea. Sediment flux was estimated by the measurement of elevation change along eight transects deployed in the study area from July 1999 to July 2000. The results of this study indicated that. first. based on the occurrence of morphological change and winds effective for sand movement. two distinct seasons were identified: a season of deposition and that of erosion. During the depositional season, spanning from November to April, effective winds were dominant and sand accumulation occurred mainly in foredunes and sequentially in dune plains. During the erosional season, from May through October, volume change was small and erosion or sand loss occurred mostly at the dunefoot of foredunes. Secondly, the research revealed that the sediment budget of Sindu coastal dune turned out to be surplus on the whole, but there are some regional differences. Deficit budgets were observed partly in secondary dunes. The utmost northern part of Sindu coastal dune was provided with abundant sand, whereas the central and northern parts were poorly supplied.

• Journal of the Korean Geophysical Society
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• v.2 no.2
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• pp.91-99
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• 1999

A high-resolution seismic profile acquired across the northeastern boundary of the Pungam Basin, one of the Cretaceous sedimentary basins in Korea, has been interpreted to delineate subsurface geological structures across the basin boundary. We identified boundary faults and unconformity surfaces of the basin and divided sediment body into three seismic depositional units (Units I, II, and III from youngest to oldest). Inferred from fault geometry and type, northeastern part of the Pungam Basin has been formed by a strike-slip fault whereas the normal faults near the boundary were formed by transtensional movement along a fault zone. A 350-400 m thick sediment layer is overlying the Precambrian gneiss. Bedding planes of Unit III are dipping westward and are closely related to an anticline in the acoustic basement. Unit II is also tilted westward, suggesting that the eastern part of the fault zone was uplifted after deposition of lower part of the sedimentary body. Afterward, the uplifted sediment layers were eroded and transported to the western part of the basin. Chaotic reflection pattern of sedimentary Units II and III may suggest that strike-slip movement along the fault zone deformed basin-filled sediments.

• Geophysics and Geophysical Exploration
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• v.18 no.2
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• pp.39-53
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• 2015

Analysis of multi-channel seismic reflection profiles acquired from the southwestern margin of Ulleung Basin reveals that the cut and fill structures, which show U-shaped or V-shaped morphology, occur on variable size. The cut and fill structure mostly consists of fine-grained sediments on the well data and is characterized by transparent or semitransparent seismic facies on the seismic section. Such cut and fill structures dominantly occur in the syn-compressional megasequence (MSQ3), which was deposited during basin deformation of late Miocene, among the four megasequences of the study area. These cut and fill structures can be divided into three groups based on their size and formation time. The cut and fill structures of Group I were formed when Dolgorae structure was active, and occurred on a small scale. The cut and fill structures of group II were formed when both Dolgorae structure and Gorae V structure were active, and the number and size of those increased compared with group I. The cut and fill structures of group III were formed when Dolgorae structure was weaken gradually but Gorae V structure kept active, and the number and size of those decreased in comparison with group II. Consequently the cut and fill structures in the southwestern margin of Ulleung basin are interpreted as submarine canyon based on spatial distribution, size and fill sediment. They were controlled by the tectonic movement in response to basin closure and tectonic-induced sediment supply variation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.1
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• pp.1-12
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• 1983

The wave and hydrologic climate at a beach location are everchanging and coastal engineers have always been interested in the deformation of the natural beach caused by wave action over short or long interval of time. The drift of sand on a beach particulary manifests itself when blocked construction of seawalls, jetties, breakerwaters and groins etc.${\cdots}$ For this reason, the understanding and evaluation of littoral drift has been especially important to the coastal engineers. The resulting of the sand drift movement, such as the type of beach profile, width of beach, storage volume of the littoral sand over the profile are rapid everchange. We have studied the geological changes due to the littoral drift on a beach with field investigation and model tests in laboratory. But, it is impossible to make quantative correct analysis because of the factors are everchange and complicate. And then, most of study are incline to qualitative analysis. In this paper, authors studied mainly on the transition of beach profile and sediment storage on the profile using statistical field data as qualitative analytical method. The used theoretical beach transition model by Sonu and Beek have developed to obtain the change of HAEUNDAE beach backed with seawall. Results of this study indicate that the transition model are useful in the analysis of beach profile changement and the littoral drift movement on the beach. Qualitative analysises for HAEUNDAE beach are as follows. 1) Transition sequence of profile has 4 major transition for one cycle. 2) Storage sediment model of beach profile by Sonu and Beek well coincided with HAEUNDAE beach. 3) Seasonal cycle has ill-balanced process for the 5-yr. investigation.