• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1593-1598
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• 2011

The purpose of this study is to perform parameter selection and develop a method for the condition monitoring of an LCD conveyance robot. To determine the vibration characteristics of the driving part of the robot, the gear mesh frequency (GMF) of the speed-reducing gearbox is calculated and confirmed by frequency analysis. In order to ensure reproducibility of the measured data, an appropriate working pattern is selected and experiments are carried out. For condition monitoring of the robot, a wireless measurement system is constructed and used in parameter selection, with the GMF as the center. A method involving the use of the standard deviation of the measured data and another method involving the use of multiple value of amplitude are proposed.

• Journal of Korea Water Resources Association
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• v.42 no.2
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• pp.105-115
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• 2009

The objectives of this study are to deduce a problem of existing subcatchment width equation in Storm Water Management Model(SWMM) and to analyze the suitability of a new adjusted subcatchment width equation on both ideally assumed watersheds and an actual urban watershed area. The problems of existing subcatchment equation are issued on the theoretical review of the equation and from the model application on different types of simplified assumed watershed. The adjusted equation, proposed in this study, that considers the pipe flows in addition to the surface flows on small subcatchment can improve the limitation of existing equation when applied on the assumed watersheds. Also, Gunja watershed with 96.3 ha is selected and collected rainfall-runoff events for the feasibility study of the proposed equation on actual urban watershed area. The results represent that the simulated flows from adjusted equation rather than the simulated flows from existing equation are well agreed with observed ones.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.2
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• pp.189-200
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• 2016

The Republic of Tajikistan has ten former uranium mining sites. The total volume of all tailings is approximately 55 million tonnes, and the covered area is more than 200 hectares. The safe management of legacy uranium mining and tailing sites has become an issue of concern. Depending on the performance requirements and site-specific conditions (location in an arid, semiarid or humid region), a cover system for uranium tailings sites could be constructed using several material layers using both natural and man-made materials. The purpose of this study is to find a feasible cost-effective cover system design for the Degmay uranium tailings site which could provide a long period (100 years) of protection. The HELP computer code was used in the evaluation of potential Degmay cover system designs. As a result of this study, a cover system with 70 cm thick percolation layer, 30 cm thick drainage layer, geomembrane liner and 60 cm thick barrier soil layer is recommended because it minimizes cover thickness and would be the most cost-effective design.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.297-302
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• 2008

The main reason of the pollution caused by soils and tailings located at discussed mines is heavy metals and AMD(acid mine drainage). Human health is affected by these pollutants which are spreaded from the abandoned mines. In this study, we try a mathematical approach to predict the pollution level of heavy metals caused by the surrounding soils of abandoned mines. The new approach is established with the correlation between the distance and pH, ORP. The change of pH and ORP can be described by the rate of initial values to experimental values. We demonstrate a realistic possibility of the mathematical approach to assess an environmental impact from disused mines cause the rate range is 0.95 to 1.03 for 60 days. Therefore our proposed approach will be useful as a few promising method for the management of heavy metals in many mines.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.136-145
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• 2011

For a massive project related to building national industrial complexes on a soft ground applied to PVD after dredging and hydraulic fill, laboratory tests were carried out using undisturbed sample taken from various depth. Piezocone penetration and dissipation tests were carried out to assess horizontal coefficient of consolidation and initial stress in field. The ground consists of upper dredged fill and lower original clay layer having both similar marine clays. It should be, however, considered as multi-layered soft ground having different initial void ratio, initial water content, initial effective stress, and permeability and compressibility with directions. To assess initial stress of those soft layers in which have different stress history related to consolidation, CPTu test results, especially excess pore water pressure, were analyzed. It allows to find out distribution of excess pore water pressure and initial stress inner original clay layer.

• The Journal of Engineering Geology
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• v.17 no.3
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• pp.339-350
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• 2007

Content, swelling, concentration, drainage of clay are critical factors that could control rock failures as well as discontinuous geological structures like faults and joints. Especially, the proportional components of clay minerals can be one of few direct indicators to a rock failure caused well by rainfall. Criticality of the role of clay mineral contents gets bigger in the slope and tunnel design. This study, using a horizontal boring core of pelitic/psammitic phyllite from the OO tunnel construction site, aims to investigate mineral composition changes related to fault distribution and their mechanical effects to the activity of these discontinuous layers (i.e., clay-filled fault layers), and eventually to define correlation among rock compositions, weathering products and rock instabilities. Field survey and lab tests were carried out for the composition and strength index of fault clay minerals within the core samples and microscopic analysis of fresh and weathered rock samples.

• Journal of the Korean GEO-environmental Society
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• v.13 no.10
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• pp.43-53
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• 2012

This study deals with the conventional consolidation methods like preloading and vertical drains. For it, Two different mechanism, i.e., increasing of permeability and evaporating of pore water were studied. The marine clays excavated in Incheon were heated at low temperature($90^{\circ}C$) to increase the permeability. Also, Microwave oven and high-temperature electric heater were used for pore water evaporation. Several points raised from the experiments. To fix them, the electric heating system was revised to upgrade the field application and drain efficiency of pore water, and the marine clays were heated by revised electric heater at high temperature($250^{\circ}C$). From Experimental result showed that results, high-temperature heater induced the pore water evaporation and displayed the excellent consolidation behavior. In addition, the cone index of heated clays were increased about 19 times, which suggested that electric heating system could be applied for ensuring the trafficability of heavy equipments.

• Journal of Korea Water Resources Association
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• v.37 no.8
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• pp.613-622
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• 2004

The simulation results of final closing by the developed model considering the flows through tide embankment of non-Darcy and through sluice gate agree well to the observed data which shows the model applicability. In comparative analysis with observed data, the simulation results by Homma(1958) are more accurate than those by Na(1987). The free flow equation with discharge coefficient, regardless of free or submerged flows, by Na based on the submergence ratio is applicable to the engineering practices. Because two simulated discharges are greater than the actual one, the correction of discharge coefficients reflecting the irregular section of actual closing gap situation is necessary. In the hydraulic analysis of final closing, the flow through tide embankment has been generally analysed by Darcy. Hydraulic analysis by the correct discharge through tide embankment of non-Darcy flow is necessary, because the ratio between flows through tide embankment and closing gap is relatively great at final closing.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.437-440
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• 2008

This study enforced to produce the planting concrete block which could be applied to various slopes economically. First of all, the physical properties was investigated with the various types of aggregate and aggregate ratio of the paste for the lead to mixture proportion of the planting concrete. As a result, the orchid stone as aggregate and 30% of aggregate ratio of the paste were used as the basic mixture proportion considering 20${\sim}$30% of maintained void ratio for the growth of plant, over 20% of capillary suction for holding water, and 3MPa as the minimum strength. For the result of the test to the new planting block which was quite different from existing planting concrete block, it could complement the problems and be possible to produce effectively and economically because various slopes like $40^{\circ}{\sim}75^{\circ}$, continual produce by extrusion, and pumping out were possible were possible.

• Journal of the Korean Geographical Society
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• v.40 no.3 s.108
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• pp.274-284
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• 2005

On the subject of Yeoungsan River Yeoungbon c and Seumjin River Seumbon e site discussing as the measuring points of discharge and Quality by the Department of Environment, this study executes the tests of proprieties and examines the methods of flow measuring and assessment. The result of this study may summarize as belows. According to the hydrogeomorphological aspects and artificial effects, Yeoungbon c and Seumbon e site are not proper for the measuring points of the water levels. Also, the methods of river discharge measuring by the specific discharge method, first tried in this study, has an enough reliability which can be used to measure the site where is difficult to measure the flow directly or to select the representative site to measure on the up and downstream. In case of accumulating the specific discharge data throughout the flow observation by seasons and periods for a long time, these may be used to measure the flow as well.