• Ocean and Polar Research
• /
• v.36 no.3
• /
• pp.209-223
• /
• 2014

The community structure of benthic meiofauna was investigated from seasonal surveys at seventeen stations off the Saemangeum area, in 2007. Ten meiofaunal taxa were identified. Nematodes were the dominant faunal group in all seasons and harpacticoids were dominant only at a few stations. The mean density of meiofauna was 383 indiv. $10cm^{-2}$, highest in May and November (434 indiv. $10cm^{-2}$), lowest in February (284 indiv. $10cm^{-2}$). Meiofaunal mean biomass was $80.49{\mu}gC{\cdot}10cm^{-2}$, highest in November ($99.54{\mu}gC{\cdot}10cm^{-2}$), lowest in February ($51.56{\mu}gC{\cdot}10cm^{-2}$). Cluster analysis revealed that the study area was composed of three benthic meiofaunal communities. There were significant correlations between major meiofaunal groups and sediment composition and the concentrations of heavy metals. The abundance of harpacticoids are positively correlated with silt (0.559, p < 0.01) and clay (0.340, p < 0.01), and negatively correlated with sand (-0.548, p < 0.01). Harpacticoids also showed positive correlations with heavy metals. The community structure of meiofauna in the study area varied seasonally in response to the change of sediment composition.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.39 no.spc1
• /
• pp.189-197
• /
• 2006

To elucidate the organic matter sources in soft-bottom macrozoobenthos at Tongyeong, Korea, macrozoobenthos and their potential food sources were sampled in May 2004, and their C and N stable isotope compositions were analyzed. In total we collected 128 macrozoobenthic species, which ranged from 465 to 3,775 individuals/$m^2$(average 2,108 ind.$m^2$) in density and from 47.8 to 539.9 gwwt/$m^2$(average 366.0 gwwt/$m^2$) in biomass. Cluster and multi-dimensional scaling analyses indicated that the macrozoobenthic community was divided into two distinct groups. Coastal inner stations, where commercial fish cages were established, were dominated by Amphioplus ancistrotus, Scoletoma longifoila and Tharyx sp., whereas open sea stations were dominated by Chaetozone spinosa, Scoletoma longifolia and Capitella capitata. ${\delta}^{13}C$ values of sedimentary organic matter showed a distinct gradient in the range of -18.4 to $-15.2\%_{\circ}$, with a declining trend from the coastal inner stations to open sea stations. This probably reflects the settling rate of organic wastes such as feces and pellets from fish cages near the coastal inner stations. The macrozoobenthos showed a broad ${\delta}^{13}C$ range from -19.5 to $-8.9\%_{\circ}$ at the coastal inner stations, and a relatively narrow range from -21.3 to $-12.9\%_{\circ}$ at the open sea stations. ${\delta}^{13}C$ values of macrozoobenthos paralleled those of sedimentary organic matter, Our isotope results suggested that macrozoobenthos near the coastal inner stations used organic wastes derived from fish cages along with phytoplankton, whereas the macrozoobenthos near the open sea stations used organic wasters derived mainly from phytoplankton.

• Journal of Internet Computing and Services
• /
• v.15 no.5
• /
• pp.95-105
• /
• 2014

In this paper, we present a novel ant-based hierarchical clustering algorithm, where ants repeatedly hop from one node to another over a weighted directed graph of k-nearest neighborhood obtained from a given dataset. We introduce a notion of node pheromone, which is the summation of amount of pheromone on incoming arcs to a node. The node pheromone can be regarded as a relative density measure in a local region. After a finite number of ants' hopping, we remove nodes with a small amount of node pheromone from the directed graph, and obtain a group of strongly connected components as clusters. We iteratively do this removing process from a low value of threshold to a high value, yielding a hierarchy of clusters. We demonstrate the performance of the proposed algorithm with synthetic and real data sets, comparing with traditional clustering methods. Experimental results show the superiority of the proposed method to the traditional methods.

• Journal of Communications and Networks
• /
• v.13 no.6
• /
• pp.664-677
• /
• 2011

In order to control interference and improve spectrum efficiency in the femtocell and macrocell overlaid system (FMOS), we propose a joint frequency bandwidth dynamic division, clustering and power control algorithm (JFCPA) for orthogonal-frequency-division-multiple access-based downlink FMOS. The overall system bandwidth is divided into three bands, and the macro-cellular coverage is divided into two areas according to the intensity of the interference from the macro base station to the femtocells, which are dynamically determined by using the JFCPA. A cluster is taken as the unit for frequency reuse among femtocells. We map the problem of clustering to the MAX k-CUT problem with the aim of eliminating the inter-femtocell collision interference, which is solved by a graph-based heuristic algorithm. Frequency bandwidth sharing or splitting between the femtocell tier and the macrocell tier is determined by a step-migration-algorithm-based power control. Simulations conducted to demonstrate the effectiveness of our proposed algorithm showed the frequency-reuse probability of the FMOS reuse band above 97.6% and at least 70% of the frequency bandwidth available for the macrocell tier, which means that the co-tier and the cross-tier interference were effectively controlled. Thus, high spectrum efficiency was achieved. The simulation results also clarified that the planning of frequency resource allocation in FMOS should take into account both the spatial density of femtocells and the interference suffered by them. Statistical results from our simulations also provide guidelines for actual FMOS planning.

• Journal of Life Science
• /
• v.19 no.8
• /
• pp.1062-1066
• /
• 2009

N-Acetylglucosamine kinase (GlcNAc kinase or NAGK; EC 2.7.1.59) catalyzes the phosphorylation of GlcNAc to GlcNAc-6-phosphate (GlcNAc-6-P). Despite detailed characterization of the enzyme itself, there have been few studies on the expression of NAGK in mammalian tissues. In the rat hippocampal neuron in culture, NAGK-immunoreactivity (IR) formed clusters in somatodendritic domains. In this study we characterized the NAGK clusters that protrude out the long axis of dendritic shafts. By double-labeling of the neurons with antibodies against NAGK and various synaptic proteins, we show that NAGK is positioned at the base of spines, while there were no NAGK protrusions into inhibitory postsynaptic sites. Immunoblot analysis showed that NAGK was included in synaptosomes but not in PSD fractions. Our results indicate that the NAGK clusters at the dendritic periphery protrude into spines.

• Clinical and Experimental Pediatrics
• /
• v.55 no.4
• /
• pp.128-135
• /
• 2012

Purpose: Unbalanced diets and decreased physical activity have contributed to increased prevalence of obesity and metabolic syndrome in adolescents. We have performed a systematic review and data analysis to examine the association between dietary pattern and metabolic syndrome risk factors in adolescents. Methods: We searched the PubMed and BioMedLib databases for appropriate articles published during the past 10 years and selected 6 articles. The studies reviewed applied factor analysis or cluster analysis to extract dietary patterns. For data analysis, we examined the association between dietary patterns and the prevalence of metabolic syndrome risk factors using data of 3,168 adolescents (13 to 18 years) obtained from 4 consecutive Korean Nutrition Health and Nutrition Examination Surveys (1998, 2001, 2005, and 2007 to 2009). Results: Our systematic review confirmed that western dietary patterns are positively associated with metabolic syndrome risk factors such as obesity and elevated triglycerides, while traditional dietary patterns were negatively associated. Data analysis found that the number of adolescents aged 16 to 18 years who had "Rice & Kimchi" dietary pattern decreased, while the number having western dietary patterns increased during the 1998 to 2009 time frame. There were no changes in the dietary patterns in adolescents aged 13 to 15 years. The risk of elevated serum triglycerides and reduced serum high density lipoprotein cholesterol was high in the "Rice & Kimchi" dietary pattern compared to the other dietary pattern groups. Conclusion: Because adolescents' dietary patterns are changing continuously and have long-term effects, further studies on the dietary patterns of adolescents and their health effects into adulthood are necessary.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.35 no.2
• /
• pp.130-134
• /
• 2002

The ovary of the rockfish, Sebastes inermis was cystovarian condition and consists of numerous ovarian lobules. Previtellogenic oocytes were embedded in the connective tissue of the ovarian lobules. As the oocytes grows, it protruded into the ovarian cavity and form grapes cluster-like structure with egg stalk-like structure. Yolk granules and zona radiata were not observed in the embedded early oocytes about 20 $\mu$m in diameter. In the oocytes about 80 $\mu$m in diameter, yolk granules with electron dense were abundant in the ooplasm near the egg stalk-like structure. However, pinocytosis was not obsened in the pore canal system of the zona radiata. In this stage, microfilaments, developed endoplasmic reticula, tubular mitochondria, granular materials with low electron density and active multivesicular bodies were observed in the egg stalk-like structure. This results suggest that the egg stalk-like structure of the rockfish are related with the oocyte attachment and exogenous vitellogenesis of the intial vitellogenic oocyte.

• Restorative Dentistry and Endodontics
• /
• v.38 no.2
• /
• pp.65-72
• /
• 2013

Objectives: To evaluate the inhibitory effect of ursolic acid (UA)-containing composites on Streptococcus mutans (S. mutans) biofilm. Materials and Methods: Composite resins with five different concentrations (0.04, 0.1, 0.2, 0.5, and 1.0 wt%) of UA (U6753, Sigma Aldrich) were prepared, and their flexural strengths were measured according to ISO 4049. To evaluate the effect of carbohydrate source on biofilm formation, either glucose or sucrose was used as a nutrient source, and to investigate the effect of saliva treatment, the specimen were treated with either unstimulated whole saliva or phosphate-buffered saline (PBS). For biofilm assay, composite disks were transferred to S. mutans suspension and incubated for 24 hr. Afterwards, the specimens were rinsed with PBS and sonicated. The colony forming units (CFU) of the disrupted biofilm cultures were enumerated. For growth inhibition test, the composites were placed on a polystyrene well cluster, and S. mutans suspension was inoculated. The optical density at 600 nm ($OD_{600}$) was recorded by Infinite F200 pro apparatus (TECAN). One-way ANOVA and two-way ANOVA followed by Bonferroni correction were used for the data analyses. Results: The flexural strength values did not show significant difference at any concentration (p > 0.01). In biofilm assay, the CFU score decreased as the concentration of UA increased. The influence of saliva pretreatment was conflicting. The sucrose groups exhibited higher CFU score than glucose group (p < 0.05). In bacterial growth inhibition test, all experimental groups containing UA resulted in complete inhibition. Conclusions: Within the limitations of the experiments, UA included in the composite showed inhibitory effect on S. mutans biofilm formation and growth.

• Journal of the Korean Chemical Society
• /
• v.60 no.1
• /
• pp.9-15
• /
• 2016

The theoretical investigation has been performed to predict detonation velocity, detonation pressure, and thermodynamic stability of HMX/LLM-116 cocrystal. All possible geometries of HMX, LLM-116, and cocrystal have been optimized at the B3LYP/cc-pVTZ level of theory. The binding energy for the trigger bond and cluster has been calculated to predict the thermodynamic stability. The MP2 binding energies were obtained using single point energy calculation at the B3LYP optimized geometries, and the density has been calculated from monte carlo integration. The detonation velocity and detonation pressure have been calculated using Kamlet-Jacobs equation, while enthalpy has been predicted at the CBS-Q level of theory.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.73.2-73.2
• /
• 2012

Matusoka & Kawara (2010) showed that the number density of the most massive galaxies (log $M/M_{\odot}=11.5-12.0$) increases faster than that of the next massive group (log $M/M_{\odot}=11.0-11.5$) during 0 < z < 1. This appears to be in contradiction to another important empirical concept of "downsizing". We attempt to understand the two observational findings in the context of the hierarchical merger paradigm using semi-analytic techniques. Our models closely reproduce the result of Matusoka & Kawara (2010). Downsizing can also be understood as larger galaxies have on average smaller assembly ages but larger stellar ages. Our fiducial models further reveal the details on the history of stellar mass growth of massive galaxies. The most massive galaxies (log $M/M_{\odot}=11.5-12.0$ at z=0), which are mostly brightest cluster galaxies, obtain roughly 70% of their stellar components via merger accretion. The role of merger accretion monotonically declines with galaxy mass: 45% for log $M/M_{\odot}=11.0-11.5$ and 20% for log $M/M_{\odot}=10.5-11.0$ at z = 0. The specific accreted stellar mass rates via galaxy mergers decline very slowly during the whole redshift range, while the specific star formation rates sharply decrease with time. In the case of the most massive galaxies, merger accretion becomes the most important channel for the stellar mass growth at z ~ 2. On the other hand, in-situ star formation is always the dominant channel in the $L_*$ galaxies.