• Journal of Environmental Impact Assessment
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• v.17 no.1
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• pp.1-9
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• 2008

Non-point pollution is caused by many diffusive sources, unlike a point pollution derived from industrial wastewater treatment plants or sewage treatment plants. Runoff of non-point pollutants is originated from rainfall or thawing in short period of time moving over and through the a ground surface. They cause ill effect on the quality of neighboring aquatic environment. To prevent effectively the wash off from non-point pollutant, it should be immediately reduced at the source or be treated after gathering of runoff water. This study has been carried out for the best width of riparian buffer zone. So we implemented the experiment in terms of its depth, width and kind of vegetations and calculated the reduction of pollutants loading. The experimental zone encompasses the watershed of Namhan River (Kyunggido Yangpyunggun Byungsanri). The region was divided into 5 land cover sectors : grass, reed, pussy willow, mixed(grass+pussy willow) and natural zone to compare effectiveness of vegetation. Water samples from four points have been collected in different depths. And the pollutant removal efficiency by sectors with different plant species was yielded through influent with one of each sample. And we obtained the correlation between the width of riparian buffer zone and the removal efficiency of pollutants. Using correlation result, the width of riparian buffer zones which needs to improve the water quality of river could be derived.

• Journal of Environmental Science International
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• v.25 no.1
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• pp.31-40
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• 2016

The purpose of this study was to analyse the runoff characteristics of non-point pollution sources in an urban watershed and determine the effectiveness of newly installed riverwater treatment system to reduce water pollution caused by storm runoff in the urban watershed. The results of this study showed that the levels of BOD5 and suspended solid were highly influenced by first-flush effect and the pollutant load of those two parameters were also very high in the urban watershed. Meanwhile, the effectiveness of riverwater treatment system to reduce the levels of BOD5 and suspended solid was relatively high, but those to reduce the levels of T-N and T-P was low, which needs some additional unit treatment process such as filtration and coagulation. Nonetheless, the riverwater treatment system tested was relatively simple in installation and operation, effective in removing many water pollutants and, most importantly, does not require much space as other treatment systems, so it could be an attractive alternative option to reduce riverwater pollution caused by storm runoff in urban watersheds.

• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.313-318
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• 2015

To study the influence of changes in river discharge on water quality of the main stem of the Geum River, we investigated variation of inflow load from tributaries with river discharge. We also studied the mixing behavior of pollutants during mixing of waters of the main stem and Gap Stream. For this study, we collected water quality data such as suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) representing pre-monsoon, monsoon, and post-monsoon events of 2013 from a website of Water Information System. Based on inflow load, the Gap and Miho streams may be ones of tributaries which may largely influence water quality of main stem in upper river region. The Suksung and Nonsan Streams seemed to further affect water quality downstream. Results of modified EMMA indicated SS and TP may have another source(besides Gap Stream) at pre-monsoon, monsoon, and post-monsoon period. In contrast, TN and organic matter (BOD, COD, TOC) were conservative at pre-monsoon and post-monsoon. However, when river discharge increased, these pollutants may also came from unspecified non-point sources. Therefore, we need to attempt to find non-point sources for the pollutants in the main channel of upper Geum River region.

• Journal of Applied Biological Chemistry
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• v.43 no.4
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• pp.254-257
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• 2000

Water quality monitoring network was established at the agricultural watershed located at the Namdae-chon watershed of Seolchon-myon, Muju-gun, Chollabuk-do, Korea which is 22,560 ha in size. Based on total amount of stream flow loads of nitrogen and phosphorus from the agricultural watershed were estimated. About 4.48 (1,011 ha), 7.02 (1,585 ha), and 86.82% (19,609 ha) of the site were used for paddy fields, upland fields, and forests, respectively. During the period of 6 months from May 1 to October 31, 1999, the total amounts of precipitation and stream flow were 993.2 mm and $148,533,000m^3$ respectively. The loads of agricultural non-point sources accrued by land use were 83,526 kg, 24,508 kg, 49,705 kg, and 215 kg for total-N, ammonia-N, nitrate-N, and total-P, respectively. Results showed that 23.4 and 0.1 % of the applied nitrogen and phosphorus fertilizers, respectively, were estimated to load into the streams as agricultural non-point sources.

• Smart Structures and Systems
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• v.24 no.5
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• pp.649-657
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• 2019

Recently, an advanced video deflectometer based on the principle of off-axis digital image correlation was presented and advocated for remote and real-time deflection monitoring of large engineering structures. In engineering practice, measurement accuracy is one of the most important technical indicators of the video deflectometer. However, it has been observed in many outdoor experiments that data drift often presents in the measured deflection-time curves, which is caused by the instability of imaging system and the unavoidable influences of ambient interferences (e.g., ambient light changes, ambient temperature variations as well as ambient vibrations) in non-laboratory conditions. The non-ideal unstable imaging conditions seriously deteriorate the measurement accuracy of the video deflectometer. In this work, to perform high-accuracy deflection monitoring, potential sources for the drift error are analyzed, and a drift error model is established by considering these error sources. Based on this model, a simple, easy-to-implement yet effective reference point compensation method is proposed for real-time removal of the drift error in measured deflections. The practicality and effectiveness of the proposed method are demonstrated by in-situ deflection monitoring of railway and highway bridges.

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.307-313
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• 2004

Clusters of galaxies are believed to constitute a population of astrophysical objects potentially able to emit electromagnetic radiation up to gamma-ray energies. Evidence of the existence of non-thermal radiation processes in galaxy clusters is indicated from observations of diffuse radio halos, hard X-ray and EUV excess emission. The presence of cosmic ray acceleration processes and its confinement on cosmological timescales nearly inevitably yields in predicting energetic gamma-ray emission, either directly deduceably from a cluster's multifreqency emission characteristics or indirectly during large-scale cosmological structure formation processes. This theoretical reasoning suggests several scenarios to actually detect galaxy clusters at gamma-ray wavelengths: Either resolved as individual sources of point-like or extended gamma-ray emission, by investigating spatial-statistical correlations with unidentified gamma-ray sources or, if unresolved, through their contribution to the extragalactic diffuse gamma-ray background. In the following I review the situation concerning the proposed relation between galaxy clusters and high-energy gamma-ray observations from an observational point-of-view.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.620-627
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• 2007

In this study a general analysis method for watersheds with the entire runoff conditions and corresponding water quality is proposed and its applicability based on the currently available information is investigated. Using the 8-day-interval data set of runoff and water quality observed by Nakdong River Environment Research Center, the flow duration curve and discharge-load relation curve for each unit watershed are established, then the load duration curve is finally constructed. This paper discusses how the load duration curve can be used in the assessment of TMDL. The entire Nakdong river watershed is also divided into prior managing areas of point sources or non-point sources in a way of general management. It is thought that LDC can be a great tool for visualizing overall probabilities of current water quality and thus for the TMDL management.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.1
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• pp.77-83
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• 2012

In this paper, an optimal solution to the harmonic reduction problem in a cascaded multilevel inverter with non-equal DC sources using a genetic algorithm (GA) is presented. Switching angles are generated for different values of modulation index by the proposed algorithm, considering minimum voltage total harmonic distortion (THD) whereas selected harmonics are controlled within the allowable limits at all desired modulation indices including the point of discontinuity. Results are stored as a look-up table to be used to control the inverter for a certain operating point. The computed angles are used in a simulated circuit in Matlab\Simulink to validate the results.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.3
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• pp.15-32
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• 2011

This study was carried out to investigate the soil characteristics and propose the management for the Monument Beobsoo Marsh, Korea. The soil properties of O.M, $Ca^{2+}$, $Na^+$ and CEC were higher and the soil properties of pH_{1:5}$ and $P_2O_5$ were lower the studied sites than other marsh sites in Korea. Although the Heavy metals such as Pb, Hg, Cd, Cu, Zn, Cr and As were lower compare to the safety standard of soil pollution in Korea, the overall conservation management plan based on long-term monitoring should be considered just because it varied by the point and non-point source pollution within the studied marsh. The source of water pollution varied due to non-point polluting origins such as sewage inlet, degraded terrain for agriculture, fishing sites, sites of removed water grasses, pesticides, chemical fertilizers, as well as fallen leaves. The creation of an artificial marsh is recommended due to the soil environment of the studied sites may be changed owing to the accumulated contaminants from the sources of both of point or non-point contaminants. The establishment of the zones of core, buffer and transition which is basic management structure of the UNESCO MaB could be applied to manage the studied site. Simultaneously the promotion of voluntary participation and education of the local residents are needed.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.225-233
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• 2007

Road runoff water is one of the non-point sources (NPSs) of pollution negatively influencing drinking water source. Numerous road runoff NPS waters have been studied for over the last decade. However, the sources of pollution can be conditional, seasonal, or accidental. Therefore, measurement of pollutant loadings in different site is necessary to estimate the effect of road runoff water. The objective of this study was to examine the quality of road runoff water from a city bridge in Seoul, Korea. This study was conducted for two years to assess annual discharge pollution loads. In this study, key water quality parameters including chemical oxygen demand ($COD_{Cr}$), biochemcial oxygen demand ($BOD_5$), total nitrogen (T-N), total phosphorus (T-P), and suspended solid (SS) were measured at 18 different events. The results showed that typically the pollutant concentrations are higher at the beginning of each event and decrease afterwards. The first 20% of the volume of the runoff from each event is transporting 46% ($COD_{Cr}$), 48% ($BOD_5$), 50% (T-N), 34% (T-P), 30% (SS), respectively. The event mean concentrations (EMCs) were $COD_{Cr}$ (199 mg/L), $BOD_5$ (41.2 mg/L), T-N (7.97 mg/L), T-P (0.42 mg/L) and SS (113 mg/L). Although the results were consistent with the previous study (Barbosa and Hvitved-Jacobsen, 1999), $COD_{Cr}$, $BOD_5$, T-N exhibit a stronger first flush effect compared to the other contaminants.