• Journal of Welding and Joining
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• v.32 no.2
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• pp.54-62
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• 2014

Manhole cover, which is usually made of grey cast iron and consists of frame and cover, should have enough strength to support the heavy traffic load. The manhole cover made of cast iron has heavy weight to handle manually and is vulnerable to impact force with its brittle characteristics. Moreover, its production process of casting has been regulated in terms of environmental pollution. In this study, steel manhole cover is proposed to substitute the cast cover with a series of structural analyses to confirm its strength to support the test load for manhole cover. The cover of the proposed steel manhole cover is made of thin circular pate and stiffeners below the plate. Rectangular columns and hollow circular plate were selected for the shape of the stiffener. In order to give enough strength for the cover to behave within elastic range in the loading, strengthening structures of the cover were varied with increasing the number and the size of the stiffeners. The results of the analyses revealed that when both the hollow circular stiffener and cross stiffeners were additionally applied at the same time to the steel cover with longitudinal stiffeners, the maximum stress level in the cover could be reduced to that level presented in the cast cover.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1753-1755
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• 2003

MOF insulating cover used in 22.9 kV substation hasn't shown good performance in terms of electrical safety because of its defect by short clearance MOF cover and each input and output wire junction part. The MOF cover is easily moved by outside environment as wind or rain weather because of different size MOF cover and insulating busing, also can be leaded to breakdown by tracking. Therefore, we propose MOF cover which effectively prevents from electrical accidents in this paper. To decrease the electric field concentrated on specific part, we roundly design the shape of MOF cover and clearance between cover and live part was adjusted to be longer than before. The proposed MOF cover is evaluated by using the electric field solution program.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.1
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• pp.29-37
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• 1999

Land cover classification is an essential basic information in natural environment management; however, land cover classification studies in Korea have not yet been proceeded to a sufficient level. At the present, only a limited number of the precedent studies that only cover definite city area has been conducted. Furthermore, there is almost no research conducted on the land cover classification schemes that could accurately classify the Korea's land cover conditions. This study primarily focuses on the land cover classification scheme which carries the most urgent priority in order to classify and to map out the Korean land cover conditions. In order to develop the most suitable land cover classification scheme, many foreign land cover classification cases and projects that are being carried out were reviewed in depth. The land cover classification scheme this study proposes comprises 3 levels : The first level consists of 7 different classes; the second level consists of 22 different classes; and the third level is made up of 50 classes. The land cover classification map will serve many important roles in natural environment management, such as the conjecture of natural habitats and estimation of oxygen production or carbon dioxide absorption capability of a forest. In water pollution modelling, the land cover classification data can be used to estimate and locate non-point sources of water pollution. If applied to a watershed, modelling it will allow to estimate the total amount of pollution from non-point sources of pollution in the water shed. The land cover classification data will also be good as a barometer data that determines defusion of air pollutants in air pollution modelling.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.96-99
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• 2003

Land cover map is a typical GIS database which shows the Earth's physical surface differentiated by standardized homogeneous land cover types. Satellite images acquired by Landsat TM were primarily used to produce a land cover map of 7 land cover classes; however, it now becomes to produce a more accurate land cover classification dataset of 23 classes thanks to higher resolution satellite images, such as SPOT-5 and IKONOS. The use of the newly produced high resolution land cover map of 23 classes for such activities to estimate non-point sources of pollution like water pollution modeling and atmospheric dispersion modeling is expected to result a higher level of accuracy and validity in various environmental monitoring results. The estimation of pollution from non-point sources using GIS-based modeling with land cover dataset shows fairly accurate and consistent results.

• Journal of computational fluids engineering
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• v.17 no.3
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• pp.18-24
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• 2012

The aerodynamic performance of the pantograph on a high speed train was compared for different pantograph covers which are designed to block the aero-acoustic noise from the pantograph. For the study, two types of cover are designed: wedge and cone types. The lift force of pantograph with cover was compared with the force of pantograph only. The comparison clarified that the cone type cover increases the sideslip angle of the flow and decreases the lift force considerably. However, the wedge type cover changes the flow direction upward and increases the lift force of the pan head. This increment of lift force compensates the decrement of lift force caused by the blocking of the flow into the pantograph lower frame due to cover. Therefore, in case of the wedge type cover, the overall lift force changes slightly compared with the cone type cover.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.767-772
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• 2008

Studies regarding the application of the impervious cover rate as a watershed management index have increased in number due to concerns over watershed management. The impervious cover rate is suggested as an index that can manage not only water quality but also water volume and the water ecosystem. This study intends to prove its applicability through the interconnection of the impervious cover rate and the water environment in Korea. Analysis of a selected watershed with reference to impervious cover rates showed that a watershed with an impervious cover rate of over 30% had a direct runoff in excess of 60% of precipitation, while a watershed with an impervious cover rate of 7% had a direct runoff of 39%. Watersheds with higher impervious cover rates were also found to have higher BOD, though different watersheds showed slightly different aspects in connection with BOD. Monitoring of benthic macroinvertebrates showed that species inhabiting clean water appear more frequently in areas with lower impervious cover rates than areas with higher impervious cover rates, and in mainstream areas, relatively larger numbers of species appeared in areas with lower impervious cover rates. This suggests that impervious cover rates can be appropriately used as an index for watershed management, as it effectively represents changes to the water environment.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.124-129
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• 2011

Since the horizontal global radiation and cloud cover are a main factor for designing any solar energy system, it is necessary to evaluate its characteristics all over the country. The work presented here are the investigation of horizontal global radiation and cloud cover in Korea. The data utilized in the investigation consist of horizontal global radiation and cloud cover collected for 27 years(1982.12~2008.12) at measuring stations across the country. The analysis shows that the annual-average daily horizontal global radiation is $3.61kWh/m^2$ and the annual-average daily cloud cover is 5.1 in Korea. We also constructed the contour map of cloud cover in Korea by interpolating actually measured data across the country.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.12-22
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• 2014

This study was carried out to classify forest communities and to aggregate forest cover types for the complex and diversified natural forest areas of Hwangaksan, Bakseoksan, Deogyusan, and Jirisan in southern region of Baekdudaegan Mountains. The vegetation data were collected by point-centered quarter sampling method. Eight hundred fifty one sample points were subjected to cluster analysis to classify 18 forest communities, which were aggregated into 7 representative forest cover types on the basis of community similarity from composition of canopy species. They were mixed mesophytic forest cover type, the others deciduous forest cover type, Quercus variabilis-Quercus serrata cover type, Quercus mongolica cover type, Pinus densiflora cover type, Carpinus laxiflora cover type, and Abies koreana cover type. The Quercus mongolica cover type was most widely distributed in the study areas, and this cover type tended to occur in the place of higher altitude as latitude was getting lower. Mixed mesophytic forest and the others deciduous forest cover type were commonly distributed in the areas of valley, on the other hand, Quercus mongolica cover type and Pinus densiflora cover type tended to be distributed in the areas of ridge.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.715-720
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• 2002

There are many global/continental or large area land cover mapping projects because land cover is one of key parameters in environmental studies. Though ground truth collection is a important and difficult task in land cover mapping, it is usually performed independently in each project without any cooperation between them. This is the background of the development of Global Land Cover Ground Truth (GLCGT) database by the cooperation of many projects and researchers. The developed GLCGT database will be used freely by any researcher. This cooperative and common development of GLCGT database will realize reliable and continuously improved land cover ground truth data. It also eliminates duplicated efforts of ground truth collection among projects.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1871-1873
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• 2000

There are many electrical accidents between bare wire and line post insulator which is degraded by long time using, causing leakage current on the surface of insulator. In this paper it is presented that the 22.9 Kv-y distribution lines are protected by binding cover which is needed from fog or rainy moisture, surges occurring by switching or lightening pulse. It is analyzed to investigate the unbalanced transfer characteristics and reflection coefficient by using binding cover and non-cover. It was tested the radio interference voltage in the test room and electric field strength by calculation between binding cover and non-cover. In the factory the leakage current causing on the surface of insulator was tested in the state of light load and heavy load.