• The Korean Journal of Ecology
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• v.19 no.2
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• pp.165-178
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• 1996

We investigated the role of competition in adaptation to varying water availability levels for two ecotypically-differentiated populations of Impatiens pallida found naturally in low- vs. high-water environments. In a greenhouse experiment, seedlings were grown in pure cultures at two densities (n=1 and 2 plants per pot) and in mixed cultures (n=2) under low-, medium- and high-water treatments. The two populations were shown to be genetically distinct across the range of environmental conditions in the greenhouse experiment, confirming previous findings. The two populations had similar morphological responses to density and water availability in pure cultures and mixtures, but the population from the high-water environment showed a greater growth response to high water availability than did the population from the low-water environment and the difference in growth between the two populations decreased from the high-water to low-water treatment. Relative competitive ability of two populations were compared under three different water treatments and two densities. Differential response to watering treatment and density were not reflected in a difference in relative competitive ability. Relative yield totals were significantly greater than 1 overall. The niche differentiation suggested by RYTs>1 may be responsible for the lack of differential competitive effects observed for populations in the three vatering treatments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1826-1835
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• 2007

In this paper, we present a new approach for automatic detection and tracking for multiple targets. We combine a highest probability data association(HPDA) algorithm for target detection with a particle filter for multiple target tracking. The proposed approach evaluates the probabilities of one-to-one assignments of measurement-to-track and the measurement with the highest probability is selected to be target- originated, and the measurement is used for probabilistic weight update of particle filtering. The performance of the proposed algorithm for target tracking in clutter is compared with the existing clustering algorithm and the sequential monte carlo method for probability hypothesis density(SMC PHD) algorithm for multi-target detection and tracking. Computer simulation studies demonstrate that the HPDA algorithm is robust in performing automatic detection and tracking for multiple targets even though the environment is hostile in terms of high clutter density and low target detection probability.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.192-195
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• 2003

The hight density sludge process (HDS) is a process that has been developed to achieve greatly increased sludge densities compared to those resulting from conventional pH modification systems. This study was carried out to apprehend variation of sludge properties and removal of metals during recycling of the sludge. The principal neutralization and settlement took place in neutralization beaker and mass cylinder. Sludge was recycled, as a volumetric ratios of 20%, 40% and 60%. The pH was controlled in neutralization tanks near 9.5. The average lime consumption rate was about 10g per L of AMD. The increment of sludge density was correlated with the volumetric ratios of recycled sludge.

• Journal of the Korean earth science society
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• v.38 no.5
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• pp.333-344
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• 2017

We present the environmental dependence of the luminosity-size relation of galaxies in the local universe (z < 0.01) along with their dependence on galaxy morphology represented by five broad types (E, dEs, S0, Sp, and Irr). The environmental parameters we consider are the local background density and the group/cluster membership together with the clustercenteric distance for the Virgo cluster galaxies. We derive the regression coefficient (${\beta}$), i.e., the slope of the line representing the least-squares fitting to the data and the Pearson correlation coefficient (c.c.) representing the goodness of the least-squares fit along with the confidence interval from bootstrap resampling. We find no significant dependence of the luminosity-size relation on galaxy morphology. However, there is a weak dependence of the luminosity-size relations on the environment of galaxies, in the sense that galaxies in the low density environment have shallower slopes than galaxies in the high density regions except for elliptical galaxies that show an opposite trend.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.11a
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• pp.1-6
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• 2000

This paper was studied on the crevice corrosion behavior of SS 400 in marine environment. In 0%, 2%, 3.5%, 5% NaCl solution, the aspect of the crevice corrosion and polarization behavior under the crevice corrosion was investigated. And Weight loss rate of SS 400 with crevice and non-crevice was measured according to the NaCl concentration. The main results obtained are as follows : 1) Under crevice corrosion, the corrosion potential become less noble as the concentration of NaCl solution increased. 2) The current density under open circuit potential was high drained as concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5%, the current density was low drained. 3) The weight loss rate of SS400 was increased as concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5%, that of SS400 was decreased.

• Advances in concrete construction
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• v.8 no.3
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• pp.199-206
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• 2019

High performance sandcretes (HPS) are new concretes characterized by particles having a diameter less than 5 mm, as well as very high mechanical strength and durability. This work consists in finding solutions to make sandcretes with good physico-mechanical and durability properties for this new generation of micro-concrete. However, upgrading ordinary sandcrete into high performance sandcrete (HPS) requires a thorough study of formulation parameters (equivalent water/binder ratio, type of cement and its dosage, kind and amount of super plasticizer, and gravel/sand ratio). This research study concerns the formulation, characterization and durability, in a sulphate environment, of a high performance sandcrete (HPS), made from local materials. The obtained results show that the rheological properties of fresh concrete and mechanical strength differ with the mineralogy, density and grain size distribution of sands and silica fume used.

• Journal of Powder Materials
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• v.30 no.3
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• pp.249-254
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• 2023

The influence of MgO addition on the densification and microstructure of alumina (Al₂O₃) was studied. Compacted alumina specimens were manufactured using ball-milling and one-directional pressing followed by sintering at temperatures below 1700℃. Relative density, shrinkage, hardness, and microstructure were investigated using analytical tools such as FE-SEM, EDS, and XRD. When the MgO was added up to 5.0 wt% and sintered at 1500℃ and 1600℃, the relative density exhibited an average value of 97% or more at both temperatures. The maximum density of 99.2% was with the addition of 0.5 wt% MgO at 1500℃. Meanwhile, the specimens showed significantly lower density values when sintered at 1400℃ than at 1500℃ and 1600℃ owing to the relatively low sintering temperature. The hardness and shrinkage data also showed a similar trend in the change in density, implying that the addition of approximately 0.5 wt% MgO can promote the densification of Al₂O₃. Studying the microstructure confirmed the uniformity of the sintered alumina. These results can be used as basic compositional data for the development of MgO-containing alumina as high-dielectric insulators.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_3
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• pp.1289-1295
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• 2023

Polyurethane foam insulation required for storing and transporting cryogenic liquefied gas is already widely used as a thermal insulation material for commercial LNG carriers and onshore due to its stable price and high insulation performance. These polyurethane foams are reported to have different mechanical performance depending on the density, and the density parameter is determined depending on the amount of the blowing agent. In this study, density-dependent polyurethane foam was fabricated by adjusting the amount of blowing agent. The mechanical properties of polyurethane foam were analyzed in the room temperature and cryogenic temperature range of -163℃ at 1.5 mm/min, which is a quasi-static load range, and the cells were observed through microstructure analysis. The characteristics of linear elasticity, plateau, and densification, which are quasi-static mechanical behaviors of polyurethane foam, were shown, and the correlation between density and mechanical properties in a cryogenic environment was confirmed. The correlation between mechanical behavior and cell size was also analyzed through SEM morphology analysis. Polyurethane foam with a density of 180 kg/m³ had a density about twice as high as that of a polyurethane foam with a density of 96 kg/m³, but yield strength was about 51% higher and cell size was about 9.5% smaller.

• Ocean Science Journal
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• v.42 no.3
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• pp.193-197
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• 2007

The food selectivity of tethered females of the copepod Calanus helgolandicus was examined by using the colorimetric approach. First, feeding behavior of the copepod did not show any differences between the red-color stained with neutral red and non-stained diets using the diatom Coscinodiscus curvatulus. Then, the copepods were fed a mixtures of two diets, the diatom C. curvatulus, stained with neutral red, and the dinoflagellate Gymnodinium sanguineum for $14\sim60$ minutes of feeding duration. The foregut colors of females were examined using a stereo-microscope and a video monitor. The foreguts of animals fed with a high density of diatoms in mixed diets showed a dark red color, whereas those fed with a high density of dinoflagellate in mixed diets were a dark yellow. The results suggest that this species of copepod may not selectively feed either one of the diets used for this study. Their feeding activity may be more likely related to the density of available prey in their environment. Therefore, this quick and easy colorimetric approach could provide very useful information, like the pre-screening procedure before designing and conducting the time-consuming and complex feeding experiments to understand the feeding ecology of copepods.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.33.1-33.1
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• 2018

Ram pressure stripping by intracluster medium (ICM) can play a crucial role in galaxy evolution in the high-density environment as seen by many examples of cluster galaxies. Although much progress has been made by direct numerical simulations of galaxies (or a galaxy) as a whole in a cluster environment, the interstellar medium (ISM) in galactic disks is not well resolved to understand responses of the ISM in details. In order to overcome this, we utilize the TIGRESS simulation suite that focuses on a local region of galactic disks and resolves key physical processes in the ISM with uniformly high resolution. In this talk, we present the results from the solar neighborhood TIGRESS model facing the ICM winds with a range of ram pressures. When ram pressure is weaker than and comparable to the ISM weight, the ICM winds simply reshape the ISM to the one-sided disk, but star formation rates remain unchanged. Although there exist low-density channels in the multiphase ISM that allow the ICM winds to penetrate through, the ISM turbulence quickly closes the channels and prevents efficient stripping. When ram pressure is stronger than the ISM weight, a significant amount of the ISM can be stripped away rapidly, and star formation is quickly quenched. While the low-density gas is stripped rapidly, star formation still occurs in the extraplanar dense ISM (1-2kpc away from the stellar disk). Finally, we quantify the momentum transfer from the ICM to the ISM using the mass-and momentum-weighted velocity distribution functions of each gas phase.