• Journal of The Geomorphological Association of Korea
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• v.24 no.1
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• pp.1-12
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• 2017

Planting trees is a very common practice in the coastal dunefields of South Korea as a way to stabilize dune landscapes and protect inland residential areas from strong winds and blown sands. On the other hand, disturbing the original foredune environment may deteriorate the ability of coastal landsto recover from coastal erosion after storms, causing a retreat of coastline. However, there is little information of this sort on the surface of forested dunefields. Airborne LiDAR or drone-based mapping is not easily applicable in such areas. In this study, we developed a digital terrain model of Dasari dunefields, Chungnam Province, based on direct topographic surveys with real-time kinematic GPS and total stations. We also analyzed previous two aerial photographs taken in 1947 and 1966, in order to detect an older landforms of the dunefields. Results suggested that there have been little changes in geomorphology of the Dasari dunefields for the last 50 years, despite continued tree plantings. Today, there are remains of U-shaped structures such as blowouts and parabolic dunes in the dunefields.

• Journal of The Geomorphological Association of Korea
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• v.24 no.4
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• pp.91-101
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• 2017

The Okjukdong dune in Daecheong Island attracts national attention because of its unique landscape that is not covered by vegetation. However, there has been little knowledge on the timing of the dune formation, associated wind regime, and conservational strategies. In this study, we used OSL dating and grain size analyses to reveal the history of the dune development. In addition, we analyzed the wind regime in the dunefield which is surrounded by artificial coastal forest. The fine sand at Okjukdong underlain by a colluvial gravel layer indicates that the dune has been developed since at least 5 ka. Aeolian sands were found to be deposited around 700 years ago. The dunefield appears to have been severely eroded 30~60 years ago. The dune landscape has been destroyed after constructing a windbreak forest around the dunefield. The sand seems to be moving south and north with the season.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.109-112
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• 2022

Lime has been used for the neutralization of acidic waste because it is cheap and available in large quantities. The resulting sludge often contains a considerable amount of unreacted lime due to alkali overdosing, even during automatic neutralization processes, which mainly arises from the poor solubility of lime. The sludge cake from lime neutralization of Ilkwang Mine also contained high percentages of calcium and magnesium. The elemental content of the sludge cake was compared with those obtained from a simulation of the lime neutralization facility installed at Ilkwang Mine. A Goldsim^® model estimated the degree of lime overdosing to be 19.1% based on the fractions of ferrous oxide. The analysis suggests that resolubilization of aluminum hydroxide could occur in the settling basin, in which pH exceeded 10 due to the continued dissolution of the overdosed lime. The present study demonstrated that chemical analysis of sludge combined with process simulation could provide a reasonable estimate of mass balance and chemistry in a neutralization facility for acid mine drainage.

• Journal of Ocean Engineering and Technology
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• v.36 no.6
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• pp.353-363
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• 2022

The azimuth thruster is mainly installed on a vessel that requires a dynamic positioning (DP) function for special purposes. When the azimuth thruster on a vessel operates for DP, the thrust loss is induced by the thruster-hull interaction. This study examined the influence of boundary conditions in numerical simulations for predicting thrust loss. Wind turbine installation vessels (WTIV) and floating production storage and offloading (FPSO) were chosen as a target vessels. In this study, two types of boundaries were defined. The first consideration is that the boundary condition was assigned with consideration of the azimuth angle of the thruster, whereas it is fixed regardless azimuth angle of the thruster. The predicted thrust loss according to these boundary conditions showed a difference. This observation originated from the current load of the vessel. Therefore, the boundary conditions for which the current load is not induced need to be designated to obtain a realistic thrust loss in a numerical simulation.

• Journal of the Korean Association of Geographic Information Studies
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• v.4 no.3
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• pp.21-30
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• 2001

This research was carried out for analyzing watershed and river topography. The method based on experience and map was mainly used, but derived data are too much to effectively analyze. Therefore some researchers have introduced computer system using GIS technique and remote sensing data. This research used GIS and remote sensing technique for classifying and analyzing watershed and river topography. Also dendrochronology method was introduced for guessing the creation times of deposits. Stream order map, sub-basin delineation map, river-bed microtopograpy were produced through this research. These results may be used in planning for Donggang conservation.

• Journal of Korea Water Resources Association
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• v.43 no.7
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• pp.625-633
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• 2010

An integrated water resources management is highly required to use efficient water and preserve water quality due to the limits of water resources development and water pollution. K-WEAP was developed, which supports the water resources planning and evaluation within a fully integrated interactive system. In this study, we present three applications of K-WEAP. First, we examined the usefulness of K-WEAP as a water resources planning tool through its application to the National Water Resources Plan. Second, the conjunctive use of surface water and groundwater in the Geum river basin with K-WEAP was evaluated, and its results show how to support to set up a sustainable groundwater management plan. Finally, we confirmed the function of the integrated water quantity and quality management in K-WEAP, which conducted by comparing the simulated results of water quality in both QUAL2E and K-WEAP.

• Ocean and Polar Research
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• v.27 no.1
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• pp.35-44
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• 2005

The bathymetric and gravity data were obtained in 2001 and 2003 during a survey of seamounts in the northwest of the Marshall Islands, western Pacific. The study areas are located in the Pigafetta Basin which is the oldest part of the Pacific plate and in the Ogasawara Fracture Zone which formed from the spreading ridge between the Izanagi and Pacific plates in the Jurassic. The densities of seamounts and the elastic thickness values of the lithosphere are calculated by using three-dimensional flexure modeling considering the constant sediment layer in the infinite plate model. Very low elastic thickness values (5km), relatively young seamounts, and old lithosphere in the east study area suggest the possibility of the rejuvenation of lithosphere by widespread volcanisms, whereas the elastic thickness values (15km), relatively old seamounts, and young lithosphere of the west study area are suitable for a simple cooling plate model of $300-600^{\circ}C$ isotherm. The gravity residuals of OSM6-1 and OSM6-2 suggest the possibility of different load density or elastic thickness. Relatively older OSM6-2 formed on the younger lithosphere with relatively thin elastic thickness, while younger OSM6-1 on the older lithosphere with relatively thick elastic thickness.

• Journal of the Korean earth science society
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• v.28 no.2
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• pp.159-168
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• 2007

This study developed earth science learning materials based on paleolithic remains in the Youngsan River basin to provide students with curiosity and interest of science. These materials consist of four activities such as orientation, tour of museum, field trip to paleolithic sites, and making of remains. More than 60% of the teachers said that these materials are likely to improve the scientific process skills of students and also suggested that these could be applied to club activity, field trip, and homework. In addition, materials seemed to help students to understand the properties of the mineral and rock. We suggested that these materials could broaden teachers' subject of teaching in science.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.481-493
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• 2009

This study was conducted to performance appraisal of Total Maximum Daily Loads (TMDLs), especially in terms of performance on development & reduction plan and water quality status of unit watershed. Because load allocations for pollution sources were predicted redundantly by uncertainty of prediction, TMDLs master plan has been frequently changed to acquire load allocation for local development. Therefore, It need to be developed more resonable prediction techniques of water pollution sources to preventing the frequent change. It is suggested that the reduction amount have to be distributed properly during the planning period. In other words, it has not to be concentrated on the specific year (especially final year of the planning period). The reason why, if the reduction amount concentrate on the final year of the planning period, allotment loading amount could not be achieved in some cases (e.g., insufficiency of budget, extension of construction duration). If the development plan was developed including uncertain developments, it is necessary to be developed reduction plan considered with them. However, some of the plans in the reduction plan could not be accomplished in some case. Because, it is not considered financial abilities of local governments. Consequently, development plan must be accomplished to avoid uncertain developments, and to consider financial assistance to support the implementation of effective plan. Water quality has been improved in many unit watersheds due to the TMDLs, especially in geum river and yeongsang/seomjin river.

• Korean Journal of Plant Taxonomy
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• v.40 no.4
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• pp.247-250
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• 2010

We report Polygonum plebeium R.Br. (Polygonaceae) as an unrecorded species from the Geumgang River, Buyeo-gun; Galmae-dong, Guri-si; the Chungju Reservoir, Jecheon-si; the Daecheong Reservoir, Okcheon-gun; and the Daecheong Reservoir, Daejeon, in Korea. It is distinguished from P. aviculare by pedicels that articulate in the middle and by its smooth and shiny achenes. The new Korean name, 'Ae-Gi-Ma-Di-Pul', is given considering the small-sized plant. In this study, a description and illustrations of the species and photos of the habitat are provided.