• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.3
• /
• pp.543-552
• /
• 2020

This study is aimed at determining an algorithm capable of estimating the erosion index of rainfall for the region of Maceió-Alagoas in the northeast of Brazil. The sample of the truncated data from 2003 to 2006 counts 26,889 droplet size distributions integrated per minute, with 680 rain events with duration longer than 10 minutes. The equation proposed to estimate erosion index used as a dependent variable and independent variable, presenting a coefficient of determination of 99%. The statistical significance validated the relation between minimum rainfall intensity and erosion.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.6
• /
• pp.1004-1009
• /
• 2011

Soil erosion in North Korea has been continued to accelerate by deterioration of topographical conditions. However, few studies have been conducted to predict the amount of soil loss in North Korea due to limited data so far. Rainfall erosivity is an important factor to predict the amount of long-term annual soil loss by USLE (universal soil loss equation). The purpose of this study is to investigate rainfall erosivity, which presented the potential risk of soil erosion by water, in North Korea. Annual rainfall erosivities for 27 stations in North Korea for 1983~2010 were calculated using regression models based on modified Institute of Agricultural Sciences (IAS) index in this study. The result showed that annual average rainfall erosivity in North Korea ranged from 2,249 to 7,526 and averaged value was $4,947MJmm\;ha^{-1}\;hr^{-1}\;yr^{-1}$, which corresponded to about 70% of annual average rainfall erosivity in South Korea. The finding was that the potential risk of soil erosion in North Korea has been accelerated by the increase of rainfall erosivity since the late 1990s.

• Journal of Aerospace System Engineering
• /
• v.14 no.2
• /
• pp.50-56
• /
• 2020

In this study, we investigated whether long short-term memory (LSTM) can be used in the future to predict F10.7 index data; the F10.7 index is a space environment factor affecting atomic oxygen erosion. Based on this, we compared the prediction performances of LSTM, the Autoregressive integrated moving average (ARIMA) model (which is a traditional statistical prediction model), and the similar pattern searching method used for long-term prediction. The LSTM model yielded superior results compared to the other techniques in the prediction period starting from the max/min points, but presented inferior results in the prediction period including the inflection points. It was found that efficient learning was not achieved, owing to the lack of currently available learning data in the prediction period including the maximum points. To overcome this, we proposed a method to increase the size of the learning samples using the sunspot data and to upgrade the LSTM model.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.8 no.3
• /
• pp.65-73
• /
• 2005

Because the geological features of Imha basin are composed of clay and shale layer, much soil particle flows into reservoir in shape of muddy water when it rains a lot. Therefore, turbidity data can be indirect-index to estimate the soil erosion of Imha basin. This study evaluated annual soil erosion using GIS-based soil erosion model and applied rainfall weighting value method by time-series rainfall data to estimate monthly soil erosion. In view of 2003 turbidity data, monthly soil erosion with rainfall weighting value is more efficient than monthly soil erosion with rainfall data.

• Journal of Korean Society on Water Environment
• /
• v.31 no.6
• /
• pp.693-699
• /
• 2015

It has been known that torrential rainfall events have been occurring worldwide due to climate change. The accelerated soil erosion has caused negative impacts on water quality and ecosystem of receiving waterbodies. Since soil security issues have been arising in various areas of the world, intensive interests have been given to topsoil management in Korea. Thus in this study, Web GIS-based computing system of physical, chemical, and biological topsoil quality indices were developed. In this study, five soil quality maps at national scale and top soil erosion potential were prepared for evaluation of soil quality based on soil erosion potential. For this system, the open source Web GIS engine, OpenGeo, was used as core engine of the system. With this system, decision makers or related personnel in areas of soil erosion Best Management Practices (BMPs) would be able to find the most appropriate soil erosion BMPs based on soil erosion potential and soil quality at the area of interest. The Web GIS system would be efficiently used in decision making processes because of ease-of-use interface and scientific data used in this system. This Web GIS system would be efficiently used because this system could provide scientific knowledge to decision makers or stakeholders. Currently various BMP database are being built to be used as a decision support system in topsoil management and topsoil quality areas.

• Proceedings of the KIEE Conference
• /
• 1999.07e
• /
• pp.2408-2410
• /
• 1999

The ageing process was checked by leakage current monitoring in Inclined-Plane Method. In order to monitor leakage current, DAS with 12-bit, 8-channel A/D converter was prepared. The monitored components of leakage current were averages of the rms and peak, max peak, cumulative charge, and the number of peaks in the ranges of 1-10, 10-20, 20-30, 30-40, 40-50, >50 mA. And, erosion depth was measured to be used as the index of the ageing. So, the results of leakage current components and erosion depth measurement were compared to find one or more components of which trends of changes were similar to that of erosion.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2010.04a
• /
• pp.239-243
• /
• 2010

This paper shows how to establish vegetation index analysis for reducing soil erosion in mountain watershed. Soil erosion results from a combination of rainfall, soil, topography, and vegetation, so we need much time and costs when analyse it. We comparatively analysed the factors of topography, soil, and vegetation with variable resources, then established GIS DB. The possibility of practical use of this DB was also analysed. The soil and vegetation information of the sediment runoff section, and the NDVI vegetation index from KOMPSAT-2 imagery were referenced for this conducting research.

• Corrosion Science and Technology
• /
• v.20 no.6
• /
• pp.466-474
• /
• 2021

A wet type scrubber for merchant vessel uses super austenitic stainless steels with pitting resistance equivalent number (PREN) of 40 or higher for operation in a harsh corrosive environment. However, it is expensive due to a high nickel content. Thus, electrochemical behavior and cavitation erosion characteristics of UNS S32750 as an alternative material were investigated. Microstructure analysis revealed fractions of ferritic and austenitic phases of 48% and 52%, respectively, confirming the existence of ferritic matrix and austenitic island. Potentiodynamic polarization test revealed damage at the interface of the two phases because of galvanic corrosion due to different chemical compositions of ferritic and austenitic phases. After a cavitation test, a compressive residual stress was formed on the material surface due to impact pressure of cavity. Surface hardness was improved by water cavitation peening effect. Hardness value was the highest at 30 ㎛ amplitude. Scanning electron microscopy revealed wave patterns due to plastic deformation caused by impact pressure of the cavity. The depth of surface damage increased with amplitude. Cavitation test revealed larger damage caused by erosion in the ferritic phase due to brittle fracture derived from different strain rate sensitivity index of FCC and BCC structures.

• Journal of Korean Society of Forest Science
• /
• v.101 no.4
• /
• pp.686-694
• /
• 2012

This study was conducted to investigate that affect benthic macroinvertebrates for installed erosion control works at a mountain torrential stream. The survey was carried out six times from April 2007 to October 2008 at two points where erosion control works were installed and at a control point in the upstream with no such works. Variations in the community structure and cluster of benthic macroinvertebrates and ecological water quality were analyzed in the survey. From the six times survey, the identified benthic macroinvertebrates were 6,922 individuals belonged to 27 species, 24 families, 13 orders, 6 classes and 4 phyla. As the average results of three surveyed sites, the dominant species was Gammarus sobaegensis of Amphipoda. The species diversity index(H') showed the highest as 1.47 at Site 2 of the fourth survey and the lowest as 0.24 at Site 2 of the sixth survey. The evenness Index(EI) showed the highest as 0.823 at Site 2 of the fourth survey and the lowest as 0.194 at Site 1 of the fifth survey. The richness index(RI) showed the highest as 2.794 at Site 1 of the first survey and the lowest as 0.291 at Site 2 of the sixth survey. The ecological score of benthic macroinvertebrate community(ESB) and individual of EPT-group were declined during the survey period. The functional feeding group(FFG) showed the highest SH types during the survey period.

• Journal of Forest and Environmental Science
• /
• v.33 no.2
• /
• pp.136-146
• /
• 2017

We selected 6 plots ($100m^2$) located 2.2-3.8 km from Minamidake Crater on the north flank of Sakurajima Volcano. We conducted a field study to investigate the effects of volcanic activity on vegetation succession and surface erosion rate. The results showed that trees growing in plots further from the crater had a greater diameter at breast height (DBH), total height, and age. In addition, these plots had a greater number of woody plants and species, as well as a greater total cross-sectional area at breast height. The Fisher-Williams index of diversity (${\alpha}$) and the proportion of evergreen broad-leaved trees were higher in plots located further from the crater. Vegetation succession in these plots was not at the level of a climax forest. From 1972 to 2015, the timing for active volcano, the depth of volcanic ash layer, the dry density, and the pH of ground surface were lower for plots located further from the crater. Furthermore, the average annual sheet erosion from 1972 to 2015 was also lower for plots located further away from the crater. Overall, plots further away from the crater have a better environment for vegetation growth and a lower dry density of the volcanic ash surface layer. It is thought that lower dry density results in increased soil permeability, which impedes surface flow. In order to prevent debris-flow disasters, caused by mud and rock flow resulting from impaired soil penetrability, it is essential to promote soil development and restore penetrability by artificial vegetation restoration.