• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.762-763
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• 2012

• Magazine of RCR
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• v.12 no.4
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• pp.40-46
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• 2017

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.443-458
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• 2005

Late Quaternary deposits of the core in the western area of the Nakdong River delta consist of four sedimentary units: Unit I, II, III and IV, in ascending order, controlled by the sea-level change since the last interglacial period. Unit I unconformable overlying Cretaceous basement rocks is composed of sandy gravel and sand deposited in a fluvial channel before the first marine transgression. Unit II composed of stiff massive mud is interpreted as a shallow marine deposits formed during the last interglacial period (probably MIS 5). The development of the fissures coated with oxidized materials in the upper part of Unit II is a feature of subaerial exposure, which indicates erosional contact with the upper Unit III. Unit III is made up of soft massive mud and soft shelly massive mud deposited in a tidal flat and a inner shelf, respectively, since the Holocene transgression (about 9,000 yr BP). Unit Ⅳ consisted of soft shell bedded mud and yellowish sandy mud was deposited in the delta environments during the regression (after about 5,000 yr BP). The lower shell bedded mud was deposited in a tidal flat and the upper sandy mud was deposited in the floodplain corresponding to present site of the Nakdong River delta.

• Journal of the Korean Geotechnical Society
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• v.31 no.12
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• pp.71-76
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• 2015

Recently, people are increasingly interested in horizontal directional drilling (HDD) to construct oil and gas pipeline and utility pipeline in the urban area as one of trenchless methods. One of major issues during the HDD is the collapse of borehole, which may be the potential causes of ground collapse. This study investigated the effect of mud pressure on the borehole stability, using finite element analysis. Since the borehole is being drilled with a certain angle, three dimensional analysis should be performed. The borehole stability was examined by applying two different types of mud pressures, i.e., uniform and non-uniform, to the exterior surface of borehole. The results show that the high mud pressure at the beginning of drilling, i.e., at shallow depth, causes the borehole collapse, whereas the borehole was stable even at high mud pressure as the drilling depth increases. It can be said that the determination of maximum mud pressure is strongly related to the drilling depth.

• Journal of the Korea Institute of Building Construction
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• v.22 no.5
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• pp.431-439
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• 2022

In this study, Neutralized red mud(LRM+S) at a pH of 6-8 was prepared by adding sulfuric acid to liquefied red mud(LRM) at a pH of 10~12. After adding LRM and LRM+S to the cement paste, the hydration heat, compressive strength, and hydration products were examined. The observed accumulated hydration heat revealed that the calorific value of the cement paste with LRM was low and its and peak was delayed when compared with that of plain cement paste(referred to as Plain), whereas the calorific value of the cement paste with LRM+S was similar to that of Plain. At the age of 28 days, the compressive strength of the cement paste with 20% LRM was 55% of the strength of Plain. Using X-ray diffraction, it was determined that the cement paste with 20% LRM exhibited a Ca(OH)₂ peak after 3 days, whereas the cement paste with 20% LRM+S and Plain exhibited a Ca(OH)₂ peak after an hour. Thus, the strength degradation of cementitious materials was improved by adding neutralized red mud prepared by adjusting the pH of highly alkaline LRM with sulfuric acid.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.386-393
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• 2023

The domestic marine healing industry is undergoing significant revitalization efforts, with a focus on understanding the efficacy and effectiveness of marine healing resources. This study establishes utilization and management standards through a detailed analysis of the active components within well-recognized marine healing mud materials. Samples of mud materials were collected from domestic tidal flats. These samples exhibited an average composition of 7.87% sand, 74.95% silt, and 17.17% clay, with a combined mud content (silt+clay)(silt+clay) consistently exceeding 90%. Notably, SiO₂ emerged as the most prevalent effective ingredient at 68.4%, followed by Al₂O₃ (13.3%)>Fe₂O₃ (4.0%)>K₂O (2.9%)>Na₂O (2.3%)>MgO (1.6%)>CaO (1.0%)>TiO₂ (0.7%), in terms of average content. Subsequently, through an analysis of effective ingredients, Si, Al, Fe, K, Na, Mg, and Ca were identified as elements demonstrating significant functionality. Among these, key indicator ingredients were selected for quality control, all of which were found to possess efficacious properties. Notably, K, Mg, and Ca exhibited particularly high concentrations. Based on these findings and referencing existing literature, it is recommended that domestic tidal flat mud resources earmarked for utilization as marine healing resources should possess a raw material mud content of no less than 70.0%. Moreover, the cumulative index components K₂O+MgO+CaO should meet or exceed a threshold of 5.0% for optimal effectiveness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12C
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• pp.1177-1183
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• 2009

In this paper, support vector machines (SVM) are applied to multi-user detector (MUD) for direct sequence (DS)-CDMA system. This work shows an analytical performance of SVM based multi-user detector with some of kernel functions, such as linear, sigmoid, and Gaussian. The basic idea in SVM based training is to select the proper number of support vectors by maximizing the margin between two different classes. In simulation studies, the performance of SVM based MUD with different kernel functions is compared in terms of the number of selected support vectors, their corresponding decision boundary, and finally the bit error rate. It was found that controlling parameter, in SVM training have an effect, in some degree, to SVM based MUD with both sigmoid and Gaussian kernel. It is shown that SVM based MUD with Gaussian kernels outperforms those with other kernels.

• Ocean and Polar Research
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• v.24 no.1
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• pp.55-61
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• 2002

Eelgrass, Zostera marina L. widely spreads throughout all the coastal areas of the Korean Peninsula. However, some previously reported eelgrass populations disappeared. The disappearance was probably caused by anthropogenic disturbance such as reclamation and pollutant or exceeded nutrient release. Eelgrass beds occurred from the intertidal to the subtidal zone, mainly in lagoon, estuaries, ports, barrier reef and bays. Eelgrass beds were also found at the intertidal mud and sand flats, subtidal mud and sandbank in more exposed areas. Habitat characteristics of eelgrass beds distributed on the coasts of the Korean Peninsula varied among coast areas. Eelgrass distributed constantly throughout the southern coast of Korea, while the distribution was limited at lagoon, bay, port, or barrier reef on the eastern coast, because of steep water depth and high wave energy in that coast. On the western coast, eelgrass mainly appeared at the intertidal and subtidal zones in islands. Sediment characteristics of the Z. marina beds varied with locality, tidal current and water motion. Sediments of Z. marina beds were composed of sand, muddy sand, sandy mud and mud. Mean grain size ranged from 1.5 to 4.1 phi.

• Geomechanics and Engineering
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• v.16 no.1
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• pp.105-112
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• 2018

This paper presents results of a compressive investigation conducted on weathered soil stabilized with ground bottom ash (GBA) and red mud (RM). The effects of water/binder ratio, RM/GBA ratio, chemical activator (NaOH and $Na_2SiO_3$) and curing time on unconfined compressive strength of stabilized soils were examined. The results show that the water/binder ratio of 1.2 is optimum ratio at which the stabilized soils have the maximum compressive strength. For 28 days of curing, the compressive strength of soils stabilized with alkali-activated GBA and RM varies between 1.5 MPa and 4.1 MPa. The addition of GBA, RM and chemical activators enhanced strength development and the rate of strength improvement was more significant at the later age than at the early age. The potential environmental impacts of stabilized soils were also assessed. The chemical property changes of leachate from stabilized soils were analyzed in terms of pH and concentrations of hazardous elements. The observation revealed that the soil mixture with ground bottom ash and red mud proved environmentally safe.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.1-5
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• 2017

In this paper, multiuser detector (MUD) based on radial basis function (RBF) is proposed and simulated for a multicode direct sequence/code division multiple access (DS/CDMA) system in a multipath fading channel. The performance of RBF-based MUD is compared with that of many suboptimal multiuser detectors in terms of bit error probability. From the simulation results, it is confirmed that the RBF-based MUD outperforms decorrelating detector, and achieves near-optimum performance under various environments. The results in this paper can be applied to design of MUD for a multicode DS/CDMA system.