• Tribology and Lubricants
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• v.13 no.2
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• pp.82-88
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• 1997

This paper describes an empirical equation which can be used to predict the engine condition of supersonic aircraft. The equation, which is derived from the trend analysis of JOAP data, represents the concentration of Fe particles in the engine oil. The result of the trend analysis shows that the concentration of Fe particles is a function of running time of engine oil. Meanwhile the slope of Fe concentration is a function of running time of engine. Threfore, the empirical equation was derived as $w=a(t_e).t_o+b$. However, the equation could not enough to diagnose the damaged part of engine quantitatively. To make up for the weak points of the equation, qualitative analysis was carried out. For that purpose wear debris were collected from the abnormal engine and analyzed by EDS to detect the damaged parts of engine.

• Elastomers and Composites
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• v.48 no.3
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• pp.225-231
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• 2013

In this study, we observed the effect of carboxylated SBR latex and zinc oxide on styrene-butadiene-styrene( SBS) composites for improving abrasion and debris. SBS composite, which added only silica, showed poor mechanical properties, NBS abrasion, and debris, caused by strong filler-filler interaction of silica. In case of adding carboxylated SBR latex, mechanical properties, NBS abrasion and debris of SBS composite were improved. Because of carboxyl group of carboxylated SBR latex interacted with silanol group of silica. Both carboxylated SBR latex and zinc oxide were added, SBS composite showed highest mechanical properties, NBS abrasion, and debris by forming ion cluster between carboxylated SBR latex and zinc oxide. By FT-IR analysis, ion clusters were confirmed that observed zinc carboxylated group stretch peak at $1550{\sim}1650cm^{-1}$ range. SBS composite, SC-4, showed excellent mechanical properties ; tensile strength $156kgf/cm^2$, elongation 936%, tear strength 59.4kgf/cm ; and excellent abrasion characteristics ; NBS abrasion 338%. Also, debris of SC-4 was minimized and showed wave-shape in fracture surface.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.274-282
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• 2014

The Korean government is considering the implementation of the marine debris pollution abatement technology program (MDPATP) to mitigate the negative impacts of marine debris and systematically manage marine debris through scientific researches such as monitoring and environmental impact assessment of marine debris. In this regard, this study attempts to analyze the economic feasibility of the MDPATP in order to provide policy-maker with useful information. To this end, the indices for economic feasibility such as net present value (NPV), benefit/cost (B/C) ratio, and internal rate of return (IRR) are presented. The results show that NPV, B/C ratio, and IRR are computed to be 45.7 billion won, 2.72, and 17.12%, respectively, which are bigger than 0, 1.0, and 5.5%, and that the MDPATP passes the cost-benefit analysis. Thus, it is concluded that it is socially profitable to conduct the MDPATP.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.135-141
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• 2010

Reliability model which can calculate the probability of performance failure of storm sewer was developed considering change of roughness coefficient in this study. Roughness coefficient should be re-evaluated due to accumulations of debris in sewer pipe. Therefore, roughness coefficient according to depth of debris in circular sewer pipe was determined for the present study. Reliability analysis was performed with the new roughness coefficient. After the analysis, it was found that capacity of storm sewer can be significantly decreased and probability of performance failure of storm sewer can be significantly increased by increasing the depth of debris in storm sewer. In this study, reliability model was applied for the Daegu and Jeonju using new roughness coefficient which was determined according to accumulation of debris in circular storm sewer. It was observed that if the depth of debris is increased, roughness coefficient is increased simultaneously and probability of performance failure of storm sewer is significantly increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.555-563
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• 2012

In earth orbit, a great number of orbital debris move around in extremely high velocity, and they become serious threats to satellites. In this study, smoothed particle hydrodynamics(SPH) is used to analyze the damage of a low earth orbit satellite due to the hypervelocity impact with orbital debris. The damage of honeycomb sandwich panel(HC/SP) used for walls of a satellite is analyzed with respect to impact velocities. For the additional analysis to examine the safety of interior components of the satellite, an attached electronic box and an offset electronic box are considered. As a result of the analysis considering the orbital debris having a probability of collision more than 2% at altitude of 685km, it is shown that the HC/SP can be perforated but only small craters are formed on both the attached electronic box and the offset electronic box.

• Journal of the Korean GEO-environmental Society
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• v.20 no.4
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• pp.23-29
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• 2019

Heavy rainfall is in causing debris flow by recent climate change and causes much damage in the downstream. The debris flow from the mountainous area runs to the downstream, repeating sedimentation and erosion, and appears as a fluidized soil-water mixture. Continuity equation and momentum equation were applied to analyze the debris flow with strong mobility, and the sedimentation and erosion velocity with fine particle fractions were also applied. This study is to analyze the behavior of debris flow at the downstream end for the variation of the amount of sediments can occur in the upstream of the mountain. Analysis of sediment volume concentration at the downstream end of the channel due to the variance of the length of pavement of the granulated soils resulted in the higher the supply flow discharge and the longer the length of pavement, the greater the difference in the level of sediment concentration and the earlier the point of occurrence of the inflection point. The results of this study will provide good information for determining the erosion-sedimentation velocity rate which can detect erosion and sedimentation on steep slopes.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.4
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• pp.263-273
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• 2015

We estimated the global inflow and stock of plastic marine debris. In South Korea, we estimated that the annual inflow of plastic marine debris (72,956 tons) was about 1.4% of annual plastics consumption (5.2 million tons) in 2012. By applying this 1.4% ratio to global plastics production from 1950 to 2013, we estimated that 4.2 million tons of plastic debris entered the ocean in 2013 and that there is a stock of 86 million tons of plastic marine debris as of the end of 2013, assuming zero outflow. In addition, with a logistic model, if 4% of petroleum is turned into plastics, the final stock of plastic marine debris shall be 199 million tons at the end. As the inflow and the stock are different units of measurement, better indicators to assess the effectiveness of inflow-reducing policies are needed. And, as the pollution from plastic marine debris is almost irreversible, countermeasures to prevent it should be valued more, and stronger preventive measures should be taken under the precautionary principle. As this is a preliminary study based on limited information, further research is needed to clarify the tendency of inflow and stock of plastic marine debris.

• Journal of the Korean Association of Geographic Information Studies
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• v.27 no.1
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• pp.99-114
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• 2024

Domestic coastal debris monitoring encounters challenges due to labor-intensive methods and limited survey scope. Consequently, research is utilizing remote sensing techniques to enhance efficiency in data collection. However, standards for domestic remote sensing based monitoring methods remain insufficient. In this study, we conducted a meta-analysis of 19 coastal debris monitoring studies utilizing drones and other remote sensing devices. We analyzed data collection methods, collected data information, monitoring target details, monitoring status, detection targets, and utilization models. Based on our meta-analysis results, we proposed monitoring criteria, recommended items, and performance standards for monitoring coastal debris using drones. Our findings define necessary conditions and standards for establishing operational guidelines for coastal debris monitoring using drones. Furthermore, we anticipate that incorporating foreign case analyses and field application results will enable the development of national-level guidelines for coastal debris monitoring utilizing remote sensing devices.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.159-159
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• 2017

• Tribology and Lubricants
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• v.15 no.3
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• pp.265-271
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• 1999

Wherever there are rotating equipment and contact between surface, there is wear and the generation of wear particles. The particles contained in the lubricating oil carry detailed and important information about the condition monitoring of the machine. This information may be deduced from particle shape, composition, size distribution, and concentration. Therefore, This paper was undertaken to Ferrography system of wear debris generated from lubricated moving machine surface. The lubricating wear test was performed under different experimental conditions using the Falex wear test of Pin and V-Block type by Ti(C, N) coated. It was shown from the test results that wear particle concentration (WPC) and wear severity Index( $I_{S}$), size distribution in normal and abnormal wear have come out all the higher value by increases sliding friction time. Wear shape is observed on the Ferrogram it was discovered a thin leaf wear debris as well as ball and plate type wear particles. This kind of large wear shape have an important effect not only metals damage, but also seizure phenomenon.