• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.173-182
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• 2008

Promoting quality of streaming service in wireless networks has attracted intensive research over the years. Instable wireless channel condition causes high transmission delay and packet loss, due to fading and interference. Therefore, they lead to degrade quality of video streaming service. The IEEE 802.11 Working Group is currently working on a new standard called IEEE 802.11e to support quality of service in WLANs. And several schemes were proposed in order to guarantee QoS. However, they are not adaptable to network condition. Accordingly, they suffered video quality degradation, due to buffer overflow or packet loss. In this paper, to promote quality of video streaming service in WLANs, we propose a cross-layer architecture based on IEEE 802.11e EDCA model. Our cross-layer architecture provides differentiated transmission mechanism of IEEE 802.11e EDCA based on priority of MPEG-4 video frames and adaptively controls the transmission rate by dropping video frames through the efficient bandwidth estimation based on distinction of each AC. Through the simulation, proposed scheme is shown to be able to improve end-to-end qualify for video streaming service in WLANs.

• The KIPS Transactions:PartB
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• v.10B no.4
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• pp.373-380
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• 2003

Most of low cost digital cameras reveal relatively high lens distortion. The purpose of this research is to compensate the degradation of image quality due to the geometrical distortion of a lens system. The proposed method consists of two stages : calculation of a lens distortion coefficient by a simplified version of Tsai´s camera calibration and subsequent image warping of the original distorted image to remove geometrical distortion based on the calculated lens distortion coefficient. In the lens distortion coefficient calculation stage, a practical method for handling scale factor ratio and image center is proposed, after which its feasibility is shown by measuring the performance of distortion correction using a quantitative image quality measure. On the other hand, in order to apply image warping via inverse spatial mapping using the result of the lens distortion coefficient calculation stage, a cubic polynomial derived from an adopted radial distortion lens model must be solved. In this paper, for the purpose of real-time operation, which is essential for embedding into an information device, an approximated solution to the cubic polynomial is proposed in the form of a solution to a quadratic equation. In the experiment, potential for real-time implementation and equivalence in performance as compared with that from cubic polynomial solution are shown.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.131-147
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• 2018

In the present study, the safety of the near surface disposal facility for low- and intermediate-level radioactive waste (LILW) is examined based on the fluid-flow simulation model. The effects of the structural design and hydrological properties of the disposal system are quantitatively evaluated by estimating the flux of infiltrated water at the boundary of the structure. Additionally, the safety margins of the disposal system, especially for the cover layer and vault, are determined by applying the various scenarios with consideration of possible facility designs and precipitation conditions. The overall results suggest that the disposal system used in this study is sufficiently suitable for the safe operation of the facility. In addition, it is confirmed that the soundness of both the cover layer and the vault have great impact on the safety of the facility. Especially, as shown in the vault degradation scenario, capability of the concrete barrier of the vault make more positive contribution on the safe operation of the facility compared to that of the cover layer.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.227-231
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• 2008

The purpose of this study is to clarify the behavior of stranded crude oil and to estimate the restoration of seawater infiltration by application of dispersant as one of cleaning techniques. We made visualization of infiltration process of seawater and stranded crude oil on the sandy beach sediments by using of a model sandy beach. Major conclusions derived from this study are as follows. The seawater infiltration volume was reduced by the stranded crude oil. However, thirty percentage of the sweater infiltration into the sediments was restored by dispersant application to the penetrated oil in sandy beach. The penetration depth of stranded oil were dropped at first falling tide, but were not significantly fluctuated after that. Moreover, oil concentration was most high within the upper 2 cm. The stranded crude oil was broken into small size droplets and dispersed into the sediments by the dispersant application. Therefore, dispersant applications play an important roles in the large increase of surface area of given volume of oil, and it resulted in promoting to biological degradation process at the oil/water interface, dispersing the stranded oil into the water column and restoration of the supplement of the dissolved oxygen and nutrients to the benthic organisms.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.1006-1015
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• 2005

We investigated the effect of hydroxyl radicals on the photolysis of triclosan (TCS), which is a potent broad-spectrum antimicrobial agent. TCS degradation during the initial reaction time of 5 min followed a pseudo-first order kinetic model ai all light intensities at a wavelength of 365 nm and at the low light intensities at a wavelength of 254 nm. The photodegradation rate significantly increased with decreasing wavelength and increasing the UV intensities. The activity of hydroxyl radicals was suppressed when methanol was used as the solvent instead of water. An increase in the photon effect was observed when the UV intensity was higher than $5.77{\times}10^{-5}$ einstein $L^{-1}min^{-1}$ at 254 nm, and lower than $1.56{\times}10^{-4}$ einstein $L^{-1}min^{-1}$ at 365 nm. The quantum yield efficiency for the photolysis of TCS was higher at 365 nm than at 254 nm among the above mentioned UV intensities. Dibenzodichloro-p-dioxin (DCDD) and dibenzo-p-dioxin were detected as intermediates at both UV intensities of $1.37{\times}10^{-4}$ and $1.56{\times}10^{-4}$ einstein $L^{-1}min^{-1}$ at 365 nm. Dichlorophenol and phenol were also detected in all cases. Based on our findings, we presented a possible mechanism of TCS photolysis.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.1
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• pp.73-86
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• 2015

The use of complimentary indicators, other than radiation dose and risk, to assess the safety of radioactive waste disposal has been discussed in a number of publications for providing the reasonable assurance of disposal safety and convincing the public audience. In this study, the radionuclide flux was selected as performance indicator to appraise the performance of engineered barriers and natural barrier in the Wolsong low- and intermediate-level waste disposal facility. Radionuclide flux showing the retention capability by each compartment of the disposal system is independent of assumptions in biosphere model and exposure pathways. The scenario considered as the normal scenario of disposal facility has been divided into intact or degraded silo concrete conditions. In the intact silo concrete, the radionuclide flux has been assessed with respect to the radionuclide retardation performance of each engineered barrier. In the degraded silo concrete, the radionuclide flux has been explored based on the performance degradation of engineered barriers and the relative significance of natural barrier quantitatively. The results can be used to optimally design the near-surface disposal facility being planned as the second project phase. In the future, additional complimentary indicators will be employed for strengthening the safety case for improving the public acceptance of low- and intermediate-level waste disposal facility.

• KIISE Transactions on Computing Practices
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• v.22 no.6
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• pp.284-289
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• 2016

In the Hadoop-based Big Data analysis model, the data movement between the legacy system and the analysis system is difficult to avoid. To overcome this problem, a unified Big Data file system is introduced so that a unified platform can support the legacy service as well as the analysis service. However, major challenges in avoiding the performance degradation problem due to the interference of two services remain. In order to solve this problem, we first performed a real-life simulation and observed resource utilization, workload characteristics and I/O balanced level. Based on this analysis, two solutions were proposed both for the system level and for the technical level. In the system level, we divide I/O path into the legacy I/O path and the analysis I/O path. In the technical level, we introduce an aggressive prefetch method for analysis service which requires the sequential read. Also, we introduce experimental results that shows the outstanding performance gain comparing the previous system.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.2
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• pp.230-236
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• 2018

Objective: Two ex vivo experiments were conducted to verify the effect of barley grain (Nusrat cultivar) treated with alkaline compounds (AC) including alum, ammonium, and sodium hydroxide or cation-exchanged organic extracts (OE) prepared from alfalfa hay, sugar beet pulp and Ulva Fasciata, on extent and digestion of starch. Methods: In the first study, the in vitro first order disappearance kinetic parameters of dry matter (DM), crude protein (CP) and starch were estimated using a non-linear model ($D_{(t)}=D_{(i)}{\cdot}e^{(-k_d{\cdot}time)}+I$, where: $D_{(t)}$ = potentially digestible residues at any time, $D_{(i)}$ = potentially digestible fraction at any time, $k_d$ = fractional rate constant of digestion (/h), I = indigestible fraction at any time). In the second experiment, the ruminal and post-ruminal disappearance of DM, CP, and starch were determined using in situ mobile nylon bag. Results: Barley grains treated with alum and alfalfa extract had a higher constant rate of starch digestion (0.11 and 0.09/h) than others. Barley grain treated with OE had a higher constant rate of CP digestion and that of treated with AC had a higher constant rate of starch digestion (0.08 and 0.11/h) compared with those of the other treatments. The indigestible fraction of starch treated with alum and sugar beet pulp extract was higher than that of the control group (0.24 and 0.25 vs 0.21). Barley grain treated with AC and OE had significant CP disappearance in the rumen, post-rumen and total tract, and also starch disappearance for post-rumen and total tract compared with the untreated (p<0.001). Conclusion: This study demonstrated that AC and OE might have positive effects on the starch degradation of the barley grain. In addition, treating barley grain with alum and sugar beet pulp extract could change the site and extend digestion of protein and starch.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.420-431
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• 2010

Simple material budget models were developed to predict the dry season water quality for a river-type reservoir in Paldang, Republic of Korea. Of specific interest were the total phosphorus (TP), chlorophyll ${\alpha}$ (Chl. ${\alpha}$), 5-day biochemical oxygen demand (BOD), and chemical oxygen demand (COD). The models fit quite well with field data collected for 20 years and have enabled the identification of the origins of organic materials in the reservoir. The critical hydraulic load that determines the usability of phosphorus for algal production appeared to be about $1.5m\;d^{-1}$. When a hydraulic load was smaller than the critical value, the concentrations of $Chl.{\alpha}$, COD, and BOD in the reservoir water became sensitive to internal algal reactions such as growth, degradation, and settling. In spite of the recent intensive efforts for organic pollutant removal from major point sources by central and local governments, the water quality in the reservoir had not been improved. Instead, the concentration of COD increased. The model analysis indicated that this finding could be attributed to the continuing increase of the algal production in the reservoir and the allochthonous load from non-point sources. In particular, the concentrations of COD and BOD of algal origin during 2000~2007, each of which is comprised of approximately one half of the total, were approximately 2.5 times higher than those observed during 1988~1994 and approximately 1.3 times higher than those between 1995~1999. The results of this study suggested that it is necessary to reduce the algal bloom so as to improve the water quality of the reservoir.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.273-278
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• 2007

As a model compound of PAHs (polycyclic aromatic hydrocarbons) phenanthrene has been regarded as a toxic material, mutagen and carcinogen in various animals. Biodegradation conditions of phenanthrene such as pH, temperature, shaking speed, stabilizer and cofactor of degrading enzymes were investigated with Trametes versicolor and its transformant T. versicolor MrP1 in YMG medium, minimal medium and soil microcosm. T. versicolor MrP1 can overexpress mrp gene encoding Mn-repressed peroxidase that is involved in fungal degradation. Biodegradations of phenanthrene by T. versicolor and T. versicolor MrP1 were optimally performed in conditions of weak-acid (pH 6.0), $30^{\circ}C$, shaken culture and medium containing 5 mM veratryl alcohol or tryptophan. In these optimal conditions, biodegradation of phenanthrene by T. versicolor MrP1 is 31% higher than that of wild type strain in a minimal medium for 20 days. Biodegradation of phenanthrene by T. versicolor MrP1 was also higher than that of wild type in soil microcosm. T. versicolor MrP1 can be a excellent candidate for the bioremediation of PAHs contaminated environments.