• Spatial Information Research
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• v.16 no.3
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• pp.279-290
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• 2008

Landslide, one of the serious natural disasters, has Incurred a large loss of human and material resources. Recently, many forecasting or alarm systems based on various kinds of measuring equipment have been developed to reduce the damage of landslide. However, only a few of these equipments are guaranteed to evaluate the safety of whole side of land slope with their accessibility to the slope. In this study, we performed some experiments to evaluate the applicability of a terrestrial LiDAR as a surveying tool to measure the displacement of a land slope surface far a slope collapsing protection system. In the experiments, we had applied a slope stability method to a land slope and then forced to this slope with a load increasing step by step. In each step, we measured the slope surface with both a total station and a terrestrial LiDAR simultaneously. As the result of Slope Fracturing analysis using all targets, the LiDAR system showed that three was 1cm RMSE on X-axis, irregularity errors on Y-axis and few errors on Z-axis compare with Total Station. As the result of Slope Fracturing analysis using continuous targets, the pattern of Slope Fracturing was different according to the location of continuous targets and we could detect a continuous change which couldn't be found using Total station. The accuracy of the LiDAR data was evaluated to be comparable to that of the total station data. We found that a LiDAR system was appropriate to measuring the behaviour of land slope. The LiDAR data can cover the whole surface of the land slope, whereas the total station data are available on a small number of targets. Moreover, we extracted more detail information about the behavior of land slope such as the volume and profile changes using the LiDAR data.

• Transactions of Materials Processing
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• v.18 no.7
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• pp.565-571
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• 2009

This paper is concerned with the analysis on the surface stress profiles of perfectly plastic material in backward extrusion process. Due to heavy surface expansion appeared usually in the backward extrusion process, the tribological conditions along the interface between the material and the punch land are very severe. In the present study, the analyses have focused to reveal the surface conditions at the contact boundary for various punch shapes in terms of surface expansion, contact pressure, and relative movement between punch and workpiece which consists of sliding velocity and distance, respectively. Punch geometries adopted in the analysis include concave, hemispherical, pointed and ICFG recommended shapes. Extensive simulation has been conducted by applying the rigid-plastic finite element method to the backward extrusion process under different punch geometries. The simulation results are summarized in terms of surface expansion, contact pressure, sliding velocity and sliding distance at different reduction in height, deformation patterns, and load-stroke relationship, respectively.

• Spatial Information Research
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• v.11 no.4
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• pp.509-518
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• 2003

Impervious surface affects urban climate, flood, and water pollution. With a higher paved rate, expanded heat containing capacity of buildings and roads raises atmospheric temperature, and increased quantity of the outflowed water brings flood during a heavy downpour. Moreover, increased non-point source pollutant load is accountable for water pollution. In this regard, it is definitely important to research and keep monitoring the current situation of paved surface, which influences urban ecosystem, disaster and pollution. In fact, collecting information on urban paved surface, which requires the time and expense, is very difficult due to its complicate structure. In order to solve the problem, this study suggested a method to utilize satellite image data for efficient survey on the current condition of paved surface. It analyzed the paved surface condition of Anyang-si by using IKONOS image and discussed the usefulness and limitation of this method.

• Environmental Engineering Research
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• v.15 no.3
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• pp.167-172
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• 2010

The effects of low impact development (LID) techniques, such as green roofs and porous pavements, on the runoff and pollutant load from an apartment complex were simulated using the Site Evaluation Tool (SET). The study site was the Olympic Village, a preexisting apartment complex in Seoul, South Korea, which has a high percentage of impervious surfaces (approximately 72% of the total area). Using the SET, the effects of replacing parking lots, sidewalks and driveways (37.5% of the total area) having porous pavements and rooftops (14.5% of the total area) with green roofs were simulated. The simulation results indicated that LID techniques reduced the surface runoff, and peak flow and pollutant load, and increased the evapotranspiration and soil infiltration of precipitation. Per unit area, the green roofs were better than the porous pavements at reducing the surface runoff and pollutant loads, while the porous pavements were better than green roofs at enhancing the infiltration to soil. This study showed that LID methods can be useful for urban stormwater management and that the SET is a useful tool for evaluating the effects of LID on urban hydrology and pollutant loads from various land covers.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.5
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• pp.697-702
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• 2010

A WIG(Wing-In-Ground effect) craft flies close to the water surface by utilizing a cushion of relatively high pressurized air between its wing and water surface. This implies that when one designs such craft it is important to have lightweight structures with adequate strength to resist external loads with some margins. To investigate this requirement, this paper deals with the structural analysis of the bottom plate of small WIG craft having a design landing weight of 1.2-ton. As building materials for the WIG craft, pre-preg carbon/epoxy composites are considered. The strength information of the bottom plate is obtained using the first-ply-failure analysis in conjunction with a mid-plane symmetric laminated plate theory. As a result, the first-ply-failure location, load and deflection of the bottom plate are obtained. The calculated strength information is compared with the water reaction load for the bottom plate of seaplanes considered when they land on the water surface -the same fluid-structure interaction mechanism as that of WIG craft. In the calculation of seaplane water reaction load information, the rules shown in FAR(Federal Aviation Regulations) Part 25 are used. Through the comparison, the structural integrity of the bottom plate for the WIG craft is checked.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.79-88
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• 1999

In this paper, the electro-deposition method for the rehabilitation of cracked concrete, based on the electro-chemical technique, is presented. The main purpose of this paper is to apply this technique to reinforced concrete members on land. After cracking with a specified load(crack width 0.5mm), 10$\times$10$\times$20cm concrete specimens with embedded steel bars were immersed in several solutions, then a constant current density between the embedded steel in concrete and an electrode in the solution was applied for 4~20 weeks. The results indicate that electro-deposits formed in this process are able to close concrete cracks and to coat the concrete surface and that formation of these electro-deposits is confirmed to have an effect of protection against detrimental materials. Therefore, it is demonstrated that the electro-deposition method can be usefully applied for the rehabilitation technique of concrete.

• Transactions of Materials Processing
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• v.16 no.7
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• pp.521-529
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• 2007

This paper is concerned with the analysis on the surface expansion of AA 2024 and AA 1100 aluminum alloys in backward extrusion process. Due to heavy surface expansion appeared usually in the backward can extrusion process, the tribological conditions along the interface between the material and the punch land are very severe. In the present study, the surface expansion is analyzed especially under various process conditions. The main goal of this study is to investigate the influence of degree of reduction in height, geometries of punch nose, friction and hardening characteristics of different aluminum alloys on the material flow and thus on the surface expansion on the working material. Two different materials are selected for investigation as model materials and they are AA 2024 and AA 1100 aluminum alloys. The geometrical parameters employed in analysis include punch corner radius and punch nose angle. The geometry of punch follows basically the recommendation of ICFG and some variations of punch geometry are adopted to obtain quantitative information on the effect of geometrical parameters on material flow. Extensive simulation has been conducted by applying the rigid-plastic finite element method to the backward can extrusion process under different geometrical, material, and interface conditions. The simulation results are summarized in terms of surface expansion at different reduction in height, deformation patterns including pressure distributions along the interface between workpiece and punch, comparison of surface expansion between two model materials, geometrical and interfacial parametric effects on surface expansion, and load-stroke relationships.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.9-17
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• 2019

Interest in renewable energy is rapidly growing around the world. One of the most popular renewable energy sources is solar power, and photovoltaic (PV) systems are the most representative route for generating solar energy. However, with the growing adoption of solar power systems, the demand for land on which to install these systems has increased, which has caused environmental degradation. Recently, floating PV systems have been designed to utilize idle water surface areas of dams, rivers, and oceans. Because floating PV systems will be exposed to harsh environmental stresses, the safety of such systems should be secured before installation. In this study, the structural robustness of a floating PV system was analyzed by conducting numerical simulation to investigate whether the system can withstand harsh environmental stresses, such as wind and wave loads. Additionally, conventional wind and wave load predictions based on the design method and the simulation results were compared. The comparison revealed that the design method overestimated wind and wave loads. The total drag of the PV system was significantly overestimated by the conventional design criteria, which would increase the cost of the mooring system. The simulation offers additional advantages in terms of identifying the robustness of the floating PV system because it considers real-world environmental factors.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.568-573
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• 2009

Because of environmental crisis, researchers are seeking and developing a new, clean, safe and renewable energy. Solar cell energy and fuel cell energy have inestimable development potential. The paper introduces hybrid photovoltaic-fuel cell generation systems supplying a remote power load and hybrid system of solar cell and fuel cell considering the advantages of stable and sustainable energy from the economic point of view. Fuel cell power system has been proven a viable technology to back up severe PV power fluctuations under inclement weather conditions. Fuel cell power generation, containing small land us, is able to alleviate the heavy burden for large surface requirement of PV power plants. In addition, the PV-fuel cell hybrid power system shows a very little potential for lifetime $CO_2$ emissions. In this paper shows the I-V characteristics of the solar module which are dependent on the power of the halogen lamp and the I-V characteristics of fuel cells which are connected in parallel. Also, it shows efficiency of the hybrid system.

• Journal of the Korean Solar Energy Society
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• v.30 no.6
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• pp.59-65
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• 2010

Analysis on turbulence intensity profile depending on wind speed is an important process to set up design condition of wind turbine in terms of fatigue load. This paper tests goodness of fit of turbulence intensity empirical equations suggested by the IEC 61400 Standards with Jejudo Gimnyeong met-tower measurement, which is erected at a seashore. Therefore sea breeze and land breeze coexist. Sea breeze case showed apparent increasing trend of turbulence intensity in a high wind speed regime due to increase of sea surface roughness. However, neither inland wind turbine standard IEC 61400-1 nor offshore wind turbine standard IEC 61400-3 fit such a trend adequately. On the other hand, the modified empirical equation of turbulence intensity of IEC 61400-3 derived from Germany FINO1 application study by considering turbulence intensity behavior in a high wind speed regime showed good agreement with the measurement. Therefore, we can reconfirm and conclude that IEC 61400-3 Ed.1 legislated in 2009 needs to be modified.