• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.466-467
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• 2008

In case of a line-to-ground fault at transmission lines, a portion of fault current will flow into the earth through the footings of the faulted tower causing electrical potential rise nearby the faulted tower footings. In this situation, any buried pipelines or structures nearby the faulted tower can be exposed to the electrical stress by earth potential rise. Although many research works has been conducted on this phenomena, there has been no clear answer of the required separation distance between tower footings and neary buried pipeline because of its dependancy on the soil electrical charactersics of the concerned area and the faulted system.

• 복합신소재구조학회 논문집
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• 제4권3호
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• pp.38-44
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• 2013

Glass fiber reinforced plastic (GRP) pipes buried underground are attractive for use in harsh environments, such as for the collection and transmission of liquids which are abrasive and/or corrosive. In this paper, we present the result of investigation pertaining to the structural behavior of GRP flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, experimental and analytical studies are conducted. In addition, vertical ring deflection is measured by the field test and finite element analysis (FEA) is also conducted to simulate behavior of GRP pipe buried underground. Based on the results from the finite element analyses considering soil-pipe interaction the vertical ring deflection behavior of buried GRP pipe is predicted. In addition, analytical and experimental results are compared and discussed.

• Journal of Information Processing Systems
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• 제14권5호
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• pp.1136-1149
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• 2018

With the increasing of urban electricity demand, making the most use of the power cable carrying capacity has become an important task in power grid system. Contrary to the rated ampacity obtained under extremely conservative conditions, this paper presents the various steady value of cable ampacity by using the changing surrounding parameters under operation, which is based on cable ampacity calculation equation under the IEC-60287 standard. To some degree, the cable ampacity analysis of actual surroundings improves the transmission capacity of cables. This paper reveals the factors that influence cable ampacity such as insulating layer thickness, allowable long-term conductor temperature, the ambient temperature, soil thermal resistance coefficient, and so on, then gives the class of the influence of these parameters on the ampacity, which plays a great role in accurately calculating the real-time ampacity and improving the utilization rate of cable in the complex external environment condition. Furthermore, the transient thermal rating of the cable is analyzed in this paper, and temperature variation of the conductor under different overload conditions is discussed, which provides effective information for the operation and control of the system.

• 한국해양공학회지
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• 제26권5호
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• pp.31-39
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• 2012

Anchors are primarily designed and constructed to resist outwardly directed loads imposed on the foundation of a structure. These outwardly directed loads are transmitted to the soil at a greater depth by the anchors. Buried anchors have been used for thousands of years to stabilize structures. Nowadays, various types of earth anchors are used for the uplift resistance of transmission towers, utility poles, submerged pipelines, and tunnels. Anchors are also used for the tieback resistance of earth-retaining structures, waterfront structures, at bends in pressure pipelines, and when it is necessary to control thermal stress. In this research we analyzed the uplift behavior of plate anchors in sand using a laboratory experiment to estimate the uplift behavior of plate anchors under various conditions. To achieve the research purpose, the uplift resistance and displacement characteristics of plate anchors caused by the embedment ratio, plate diameter, and loading rate were studied, compared, and analyzed in various cases.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.379-381
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• 2003

The sharing of common corridors by electric power transmission lines and pipelines is becoming more common place. However, such corridor sharing can result in undesired coupling of electromagnetic energy from the power lines to the near facilities. This causes induced voltages on underground metallic pipelines due to the power line currents. This could cause AC corrosion in the pipeline, which could in turn lead to disastrous accidents, such as gas explosion or oil leakage. This paper investigates for the limitation of induced voltage on the buried metal structures which is used in the inside and outside of the country. And then we measure the earth resistance and leakage current of 22.9kV distribution lines and pipe to soil potential of near pipelines in Seoul Korea. Hereby we can see the leakage current flowing through the earthing electrode have an effect on near pipelines.

• Environmental Engineering Research
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• 제19권3호
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• pp.185-195
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• 2014

Despite the enormous technical and economic efforts to improve environmental conditions, currently about 40% of the global population (or 2 billion people) are still lack access to safe water supply and adequate sanitation facilities. Pollution problems and transmission of water- related diseases will continue to proliferate. The rapid population growth and industrialization will lead to a reduction of arable land, thus exacerbating the food shortage problems and threatening environmental sustainability. Natural systems in this context are a transdisciplinary approach which employs the activities of microbes, soil and/or plants in waste stabilisation and resource recovery without the aid of mechanical or energy-intensive equipments. Examples of these natural systems are: waste stabilisation ponds, aquatic weed ponds, constructed wetlands and land treatment processes. Although they require relatively large land areas, the natural systems could achieve a high degree of waste stabilisation and at the same time, yield potentials for waste recycling through the production of algal protein, fish, crops, and plant biomass. Because of the complex interactions occurring in the natural systems, the existing design procedures are based mainly on empirical or field experience approaches. An integrated kinetic model encompassing the activities of both suspended and biofilm bacteria and some important engineering parameters has been developed which could predict the organic matter degradation in the natural systems satisfactorily.

• Parasites, Hosts and Diseases
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• 제54권5호
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• pp.565-572
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• 2016

Whilst archaeological evidence for many aspects of life in ancient China is well studied, there has been much less interest in ancient infectious diseases, such as intestinal parasites in past Chinese populations. Here, we bring together evidence from mummies, ancient latrines, and pelvic soil from burials, dating from the Neolithic Period to the Qing Dynasty, in order to better understand the health of the past inhabitants of China and the diseases endemic in the region. Seven species of intestinal parasite have been identified, namely roundworm, whipworm, Chinese liver fluke, oriental schistosome, pinworm, Taenia sp. tapeworm, and the intestinal fluke Fasciolopsis buski. It was found that in the past, roundworm, whipworm, and Chinese liver fluke appear to have been much more common than the other species. While roundworm and whipworm remained common into the late 20th century, Chinese liver fluke seems to have undergone a marked decline in its prevalence over time. The iconic transport route known as the Silk Road has been shown to have acted as a vector for the transmission of ancient diseases, highlighted by the discovery of Chinese liver fluke in a 2,000 year-old relay station in northwest China, 1,500 km outside its endemic range.

• Geomechanics and Engineering
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• 제11권6호
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• pp.771-785
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• 2016

The thermal conductivity of soils is an important property in energy-related geotechnical structures, such as underground heat pumps and underground electric power cable tunnels. This study explores the effects of geotechnical engineering properties on the thermal conductivity of soils. The thermal conductivities of quartz sands and Korean weathered silty sands were documented via a series of laboratory experiments, and its variations with effective stress, porosity, and water saturation were examined. While thermal conductivity was found to increase with an increase in the effective stress and water saturation and with a decrease in porosity, replacing air by water in pores the most predominantly enhanced the thermal conductivity by almost one order of magnitude. In addition, we have suggested an improved model for thermal conductivity prediction, based on water saturation, dry thermal conductivity, saturated thermal conductivity, and a fitting parameter that represents the curvature of the thermal conductivity-water saturation relation.

• Geomechanics and Engineering
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• 제17권2호
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• pp.165-173
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• 2019

Plate anchors are generally used for structures like transmission towers, mooring systems etc. where the uplift and lateral forces are expected to be predominant. The capacity of anchor plate can be increased by the use of geosynthetics without altering the size of plates. Numerical simulations have been carried out on three different sizes of square anchor plates. A single layer geosynthetic has been used as reinforcement in the analysis and placed at three different positions from the plate. The effects of various parameters like embedment ratio, position of reinforcement, width of reinforcement, frequency and loading amplitude on the pull out capacity have been presented in this study. The load-displacement behaviour of anchors for various embedment ratios with and without reinforcement has been also observed. The pull out load, corresponding to a displacement equal to each of the considered maximum amplitudes of a given frequency, has been expressed in terms of a dimensionless breakout factor. The pull out load for all anchors has been found to increase by more than 100% with embedment ratio varying from 1 to 6. Finally a semi empirical formulation for breakout factor for square anchors in reinforced soil has also been proposed by carrying out regression analysis on the data obtained from numerical simulations.

• Structural Monitoring and Maintenance
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• 제9권1호
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• pp.1-27
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• 2022

Extensive laboratory tests were conducted to investigate the effect of load amplitude, geogrid position, and number of geogrid layers, thickness of ballast layer and clay stiffness on behavior of reinforced ballast layer and induced strains in geogrid. A half full-scale railway was constructed for carrying out the tests, the model consists of two rails 800 mm in length with three wooden sleepers (900 mm × 10 mm × 10 mm). The ballast was overlying 500 mm thickness clay in two states, soft and stiff state. Laboratory tests were conducted to investigate the response of the ballast and the clay layers where the ballast was reinforced by a geogrid. Settlement in ballast and clay, soil pressure and pore water pressure induced in the clay were measured in reinforced and unreinforced ballast cases. It was concluded that the effect of frequency on the settlement ratio is almost constant after 500 cycles. This is due to that the total settlement after 500 cycles, almost reached its peak value, which means that the ballast particles become very close to each other, so the frequency is less effective for high contact particles forces. The average maximum vertical stress and pore water pressure increased with frequency.