• Journal of KIISE:Computer Systems and Theory
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• v.28 no.5
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• pp.213-217
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• 2001

Excessive memory buffer requirement in continuous media playback is a serious impediment of wide spread usage of on-line multimedia service. Skewed access frequency of available video files provides an opportunity of re-using the date blocks which has been loaded by one session for later usage. We present novel algorithm which minimizes the buffer requirement in multiple sessions of multimedia playbacks. In continuous media playback originated from the disk, a certain amount of memory buffer is required to synchronize asynchronous disk. Read operation and synchronous playback operation. As aggregate playback bandwodth increases, larger amount of buffer needs to be allocated for this synchronization purpose. The focus of this work is to study the asymptotic behavior of the synchronization buffer requirement and to develop an algorithm coping with this excessive buffer requirement under bandwidth congestioon. We argue that in a large scale continuous media server, it may not be necessary to read the blocks for each session directly from the disk. The beauty of our work lies in the fact that it dynamically adapts to disk utilization of the server and finds the optimal way of servicinh the individual sessions while minimizing the overall buffer space requirement. Optimality of the proposed algorithm is shown by proof. The effectiveness and performance of the proposed scheme is examined via simulation.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.1-9
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• 1999

Numerous observations revealed strong evidence of increased middle ultraviolet radiation or UV-B (280 ~ 320 nm) at the earth's surface resulting from stratospheric ozone depletion. UV is the waveband of electromagnetic radiation which is strongly absorbed by nucleic acids and proteins, thus causing damage to living systems. It has been recorded in the East Sea, Korea that solar UV-B impinging on the ocean surface penetrates seawater to significant depths. Recent researches showed that exposure to UV-B for as short as 2h at the ambient level (2.0 Wm$^{-2}$) decreased macroalgal growth and photosynthesis and destroyed photosynthetic pigments. These may suggest that UV-B could be an important environmental factor to determine algal survival and distribution. Some adaptive mechanisms to protect macroalgae from UV-damage have been found, which include photoreactivation and formation of UV-absorbing pigments. Post-illumination of visible light mitigated UV-induced damage in laminarian young sporophytes with blue the most effective waveband. The existence of UV-B absorbing pigments has been recognized in the green alga, Ulva pertusa and the red alga, Pachymeniopsis sp., which is likely to exert protective function for photosynthetic pigments inside the thalli from UV-damage. Further studies are however needed to confirm that these mechanisms are of general occurrence in seaweeds. Macroalgae together with phytoplankton are the primary producers to incorporate about 100 Gt of carbons per year, and provide half of the total biomass on the earth. UV-driven reduction in macroalgal biomass, if any, would therefore cause deleterious effects on marine ecosystem. The ultimate impacts of increasing UV-B flux due to ozone destruction are still unknown, but the impression from UV studies made so far seems to highlight the importance of setting up long-term monitoring system for us to be able to predict and detect the onset of large -scale deterioration in aquatic ecosystem.

• Journal of KSNVE
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• v.10 no.6
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• pp.1059-1066
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• 2000

In this paper. a new indirect feedback active noise control (ANC) scheme barred on the fundamental frequency estimation is proposed for systems with a harmonic noise. When reference signals necessary for feedforward ANC configuration are difficult to obtain, the conventional ANC algorithms for multi-tonal noise do not measure the reference signals but generate them with the estimated frequencies.$^{(4)}$ However, the beating phenomena, in which certain frequency components of the noise vanish intermittently, may make the adaptive frequency estimation difficult. The confusion in the estimated frequencies due to the beating phenomena makes the generated reference signals worthless. The proposed algorithm consists of two parts. The first part is a reference generator using the fundamental frequency estimation and the second one is the conventional feedforward control. We propose the fundamental frequency estimation algorithm using decision rules. which is insensitive to the beating phenomena. In addition, the proposed fundamental frequency estimation algorithm has good tracking capability and lower variance of frequency estimation error than that of the conventional cascade ANF method.$^{(4)}$ We are also able to control all interested modes of the noise, even which cannot be estimated by the conventional frequency estimation method because of the poor S/N ratio. We verify the performance of the proposed ANC method through simulations for the measured cabin noise of a passenger ship and the measured time-varying engine booming noise of a passenger vehicle.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.10
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• pp.520-529
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• 2005

A feature-based 3D modeling algorithm is presented in this paper. Since conventional methods use depth-based techniques, they need much time for the image matching to extract depth information. Even feature-based methods have less computation load than that of depth-based ones, the calculation of modeling error about whole pixels within a triangle is needed in feature-based algorithms. It also increase the computation time. Therefore, the proposed algorithm consists of three phases, which are an initial 3D model generation, model evaluation, and model refinement phases, in order to acquire an efficient 3D model. Intensity gradients and incremental Delaunay triangulation are used in the Initial model generation. In this phase, a morphological edge operator is adopted for a fast edge filtering, and the incremental Delaunay triangulation is modified to decrease the computation time by avoiding the calculation errors of whole pixels and selecting a vertex at the near of the centroid within the previous triangle. After the model generation, sparse vertices are matched, then the faces are evaluated with the size, approximation error, and disparity fluctuation of the face in evaluation stage. Thereafter, the faces which have a large error are selectively refined into smaller faces. Experimental results showed that the proposed algorithm could acquire an adaptive model with less modeling errors for both smooth and abrupt areas and could remarkably reduce the model acquisition time.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.94-101
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• 2008

The aim of this study was to assess the responses of mixed function oxygenase (MFO) and antioxidative systems of feral Javelin goby, Acanthogobius hasta, caught in two sites of different pollution level in Shihwa lake, which has been a highly polluted lake by organic pollutants from nearby industrial complexes and sites. Enzymes analyzed in phase I of MFO system are cytochrome P450 (CYP), NADPH-cytochrome P450 reductase (P450R), NADH-cytochrome b5 reductase (b5R), and ethoxyresorufin deethylase (EROD). Phase II enzyme of glutathione S-transferase (GST) in MFO system was also investigated. Moreover, oxidative-enzyme system including catalase (CAT), glutathione reductase (GR) and total-glutathione peroxidase (GPX) activities and glutathione concentration in both of oxidized (GSSG) and reduced form (GSH) were determined. P450R, b5R, and GST activities of fish are relatively high in the polluted area, whereas hepatic EROD activity levels of fish in polluted area were lower than those of unpolluted area. CYP concentrations are not different between areas. These results indicated that feral Acanthogobius hasta were adaptive to highly polluted environment and exposed to oxidative stress in Shihwa lake.

• Journal of The Korean Association For Science Education
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• v.36 no.4
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• pp.629-641
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• 2016

Understanding of how teachers change instruction can help predict what kind of educational materials is supportive or appropriate. On the basis of this idea, we explored elementary teachers' PCK progression on specific topics of astronomy: planet size and distance in solar system. To identify the development of PCK over time, we utilized learning progression (LP) as a conceptual framework. The progression of teacher PCK can also be illustrated as the hypothetical pathway from novice to expert like LP. Eight 5th grade elementary teachers participated in this study. We observed participating teachers' astronomy classes with the same topic. In order to document topic-specific PCK of participating teachers, we developed an analytic protocol consisting of four categories: knowledge of curriculum, knowledge of teaching strategies, knowledge of assessment, and astronomical thinking practice. In addition, we monitored the changes in the four participating teachers' PCK for two years in order to validate the evidences of the PCK progression. Participating teachers in this study took some intervention by attending a four-week pre-meeting with the researchers to profile an adaptive instruction. Through this research, we profiled four and five different levels of PCK progressions in three knowledge components (curriculum, teaching strategies, student assessment) and one astronomical thinking practice (systems thinking), respectively. Participating teachers demonstrated various levels and pathways in each component of PCK. This study released the empirical evidences in fostering instructional scaffolding, which is appropriate to the level of PCK of science teachers on specific topic.

• The Journal of the Acoustical Society of Korea
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• v.31 no.6
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• pp.373-383
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• 2012

The performance of underwater acoustic communication system is sensitive to the Doppler shift and ISI(Inter-Symbol Interference). Therefore, the simulation algorithm needs to consider time-spread due to multipath arrivals which cause the ISI, and time-varying Doppler shift along with moving source and receiver. For this purpose, VirTEX(Virtual Time series EXperiment) based on Ray model has been developed. In this paper, VirTEX is used to compare the characteristics of ocean waveguide from the experimental data and illustrate the performance. The CIR(Channel Impulse Response) that characterizes the multipath arrivals with representative time-spread due to multipath arrivals is compared between numerically simulated and experimental probe signal. Also, the communication performance analysis for BER(Bit Error Rate) is compared between numerically simulated and experimental data signal. As a result, VirTEX can be useful as a simulation tool for evaluating the performance of underwater acoustic communication system.

• The Korean Journal of Food And Nutrition
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• v.29 no.3
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• pp.431-437
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• 2016

Macrophages play a pivotal role in the innate and adaptive immune systems. This study investigated the immuno-modulatory activities of polysaccharides separated from Chrysanthemum zawadskii var. latilobum (CZPS) in macrophages. Polysaccharides from Chrysanthemum zawadskii var. latilobum were extracted by the ethanol precipitation method. RAW 264.7 mouse macrophage cell line was treated with CZPS (4 to $128{\mu}g/mL$), and there was no cytotoxicity at a dose below $32{\mu}g/mL$. The levels of nitric oxide (NO) and pro-inflammatory cytokines (tumor necrosis factor (TNF)-${\alpha}$ and interleukin (IL)-6, IL-$1{\beta}$) production in the CZPS treated group ($32{\mu}g/mL$) were $6.5{\pm}0.12{\mu}m$ (NO), $1252.8{\pm}79.85$ (TNF-${\alpha}$), $305.4{\pm}29.41$ (IL-6), and $683.3{\pm}59.71$ (IL-$1{\beta}$), respectively, and they were significantly increased when compared to the control group; $2.2{\pm}0.03{\mu}m$ (NO), $452.3{\pm}38.34$ (TNF-${\alpha}$), $31.7{\pm}5.75$ (IL-6), and $184.1{\pm}11.52$ (IL-$1{\beta}$). Additionally, protein expression of inducible nitric oxide synthase (iNOS) and phosphorylation of MAPKs and NF-${\kappa}B$ expression were significantly increased upon CZPS treatment. Therefore, these results indicated that polysaccharides separated from Chrysanthemum zawadskii var. latilobum (CZPS) may have a potential immunomodulatory activity in macrophages through MAPKs and NF-${\kappa}B$ signaling, and this information is useful for the development of immune enhancing adjuvant materials using a natural ingredient.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.655-666
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• 2013

Lately, intensity and frequency of natural disasters such as flood are increasing because of abnormal climate. Casualties and property damages due to large-scale floods such as Typhoon Rusa in 2002 and Typhoon Maemi in 2003 rapidly increased, and these show the limits of the existing disaster prevention measures and flood forecasting systems regarding irregular climate changes. In order to efficiently respond to extraordinary flood, it is important to provide effective countermeasures through an inundation model that can accurately simulate flood inundation patterns. However, the existing flood inundation analysis model has problems such as excessive take of analysis time and accuracy of the analyzed results. Therefore, this study conducted a flood inundation analysis by using the Gerris flow solver that uses quadtree grid, targeting the Baeksan Levee in the Nakdong River Basin that collapsed because of a concentrated torrential rainfall in August, 2002. Through comparisons with the FLUMEN model that uses unstructured grid among the existing flood inundation models and the actual flooded areas, it determined the applicability and efficiency of the quadtree grid-based flood inundation model of the Gerris flow solver.

• Journal of Microbiology and Biotechnology
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• v.30 no.9
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• pp.1420-1429
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• 2020

Corynebacterium glutamicum, an important industrial strain, has a relatively slower reproduction rate. To acquire a growth-boosted C. glutamicum, a descendant strain was isolated from a continuous culture after 600 generations. The isolated descendant C. glutamicum, JH41 strain, was able to double 58% faster (t_d=1.15 h) than the parental type strain (PT, t_d=1.82 h). To understand the factors boosting reproduction, the transcriptomes of JH41 and PT strains were compared. The mRNAs involved in respiration and TCA cycle were upregulated. The intracellular ATP of the JH41 strain was 50% greater than the PT strain. The upregulation of NCgl1610 operon (a putative dyp-type heme peroxidase, a putative copper chaperone, and a putative copper importer) that presumed to role in the assembly and redox control of cytochrome c oxidase was found in the JH41 transcriptome. Plasmid-driven expression of the operon enabled the PT strain to double 19% faster (t_d=1.82 h) than its control (t_d=2.17 h) with 14% greater activity of cytochrome c oxidase and 27% greater intracellular ATP under the oxidative stress conditions. Upregulations of genes those might enhance translation fitness were also found in the JH41 transcriptome. Plasmid-driven expressions of NCgl0171 (encoding a cold-shock protein) and NCgl2435 (encoding a putative peptidyl-tRNA hydrolase) enabled the PT to double 22% and 32% faster than its control, respectively (empty vector: t_d=1.93 h, CspA: t_d=1.58 h, and Pth: t_d=1.44 h). Based on the results, the factors boosting growth rate in C. gluctamicum were further discussed in the viewpoints of cellular energy state, oxidative stress management, and translation.