• Journal of Korea Foundry Society
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• v.39 no.1
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• pp.7-13
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• 2019

Few studies of large blooms over 700 mm thick among those used for the forging of raw materials have been reported. The cooling rate difference between the surface and the center of a large bloom is large, and the degradation of the mechanical properties is likely in cases involving excessively coarse precipitates resulted from the slow cooling rate of a large bloom after casting. Therefore, a schematic investigation of the growth behaviors of precipitates while varying their locations in blooms is necessary. The dissolution behaviors of precipitates were investigated by simulating a reheating process during which the bloom is heated to a high temperature. The segregation behavior of the as-cast large bloom was also investigated. Reheating specimens were obtained after an isothermal heat treatment at $1150^{\circ}C$ with various holding times to simulate the reheating process, with the samples undergoing a subsequent water quenching step. The precipitates were extracted using an electrolytic extractor and a particle size analysis was conducted with the aid of SEM, EDS, and TEM. In the present work, Al oxide, MnS and Nb carbide were mainly observed.

• Journal of Korea Multimedia Society
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• v.11 no.12
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• pp.1688-1696
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• 2008

We propose a hierarchical service management method using Bloom filters for large MANETs. In this paper, a MANET is comprised of logical grid hierarchy, and each mobile node within the lowest service region multicasts the Attenuated Bloom Filter (ABF) for services itself to other nodes within the region. To advertise and discovery a service efficiently, the server node of the lowest server region sends the Summary Bloom Filter (SBF) for the ABFs to the server node of upper server region. Each upper server has the set of SBFs for lower vicinity service regions. The traffic load of the proposed method is evaluated by an analytical model, and is compared with that of two alternative advertisement solutions: complete advertisement and no advertisement. As a result, we identify that the traffic load of the proposed method is much lower than that of two alternative advertisement solutions.

• Proceedings of the KSRS Conference
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• v.1
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• pp.328-331
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• 2006

Eight years of SeaWiFS data quantify variability in the time/space patterns of spring bloom development in the Gulf of Maine (GOM). Maximum and earliest spring bloom are usually observed over Georges Bank, later on the deep basins from the west to the east GOM, and latest development along the eastern Maine coast in cold, tidally mixed water. Pronounced interannual variability of spring bloom timing, spatial position, and magnitude are shown in the GOM. Strongest negative anomalies are present in April 1998 and 2001 over Georges Bank and the eastern GOM, and in January to April of 2005 over the most of GOM. Positive anomalies are strong in April 2001, 2003 and 2004 in varying locations as well as in February and March 1999. It is suggested that interannaul variability in spring phytoplankton bloom concentrations is strongly associated with changes in water mass and stratification which might be influenced by basin-scale forcing due to large climate change.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.3
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• pp.457-464
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• 2017

The large breeding of algae in rivers has caused the algal bloom and has becoming a serious national problem for the safety of water sources. Therefore, in order to supply stable water resources through securing clean water, it is necessary to develop technology for prevention of water pollution caused by algal bloom. The purpose of this study is to improve the water quality management ability of river by applying the algal bloom detection technique using UAV. Unmanned aerial images were acquired for the Dodong in the middle region of the Nakdong River where algal bloom are frequent. In addition, the phytoplankton concentration was acquired through the sampling of algal bloom and the examination of water quality. Correlation between phytoplankton concentrations and the results of applying the algal bloom index to the Unmanned aerial images showed a strong positive correlation. The remote sensing method suggested in this study is expected to improve the initial response capability of river water pollution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1113-1120
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• 2017

As the size of the data is getting larger and larger due to improvement of the telecommunication techniques, it would be main issues to develop and process the database. The bloom filter used to lookup a particular element under the given set is very useful structure because of the space efficiency. In this paper, we analyse the main factor of the false positive and propose the new parallel type bloom filter in order to minimize the false positive which is caused by other hash functions. The proposed method uses the memory as large as the conventional bloom filter use, but it can improve the processing speed using parallel processing. In addition, if we use the perfect hash function, the insertion and deletion function in the proposed bloom filter would be possible.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.503-509
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• 2005

The growth characteristic of a predominant planktonic blooming species, Mallomonas elongata in a small shallow eutrophic pond was investigated In the field (from October 2004 to September 2005) and laboratory, Dense blooming (max. 17,600 cells $mL^{-1}$) of this silica-scaled chrysophytes was observed for a short time period in early spring (water temperature 12-$18^{\circ}C$ and pH 8.4-9.5), The growth characteristics of M. elongata isolated from this pond was investigated at various temperatures and pH under batch culture. The unialgal culture of M. elongata showed maximum growth rate (${\mu}max$) at $15^{\circ}C$ similar to the natural conditions. However, the optimal pH of the isolated batch culture was lower than the pond water pH at which M. elongata appeared in large population density.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.290-296
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• 2004

The effects of potassium, sodium, calcium, magnesium, and iron on cyanobacterial bloom potentials were investigated in Daechung Reservoir, Korea. Potassium showed the highest correlation with the cyanobacterial cell number (r=0.487, P<0.05) and phycocyanin concentration (r=0.499, P<0.05). However, it was not likely that the potassium had directly affected the bloom formation, because the variations of its concentration were not significantly large. In contrast, the Fe concentration fluctuated drastically and exhibited a negative correlation with the cyanobacterial cell number (r=- 0.388, P<0.1) and phycocyanin concentration (r=-0.446, P<0.05). Accordingly, the K:Fe atomic ratio would appear to reflect the extent of cyanobacterial bloom more precisely than K or Fe alone. The K:Fe ratio specifically correlated with cyanobacterial percentage, the cyanobacterial cell number and phycocyanin concentration (r=0.840, P<0.001; r=0.416, P<0.05; r=0.522, P<0.01, respectively). With the K:Fe atomic ratio of over 200, the chlorophyll-a concentration, cyanobacterial cell number, and phycocyanin concentration exceeded $10\mu$g $1^{-1}$20,000 cells $ml^{-1}$, and 20 pM, respectively, the general criteria of eutrophic water.

• Journal of Korean Elementary Science Education
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• v.31 no.1
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• pp.1-12
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• 2012

The purpose of this study was to explore instructional objectives of 'Wise Life' based on Bloom's Revised Taxonomy of Educational Objectives. It was to extend understanding the 7th and the revised Wise Life 2007 as well. The written objectives of two curriculum of Wise Life were divided into two, the 'knowledge' dimension and the 'cognitive process' dimension based on Bloom's Revised Taxonomy of Educational Objectives. Major activity subjects presented in the 7th and the revised Wise Life 2007 were dominantly the basic inquiry activity types. It was found from this research that the 'factual' knowledge of the 'knowledge' dimension and the 'understand' of the 'cognitive process' dimension took a large proportion of the revised Wise Life 2007 objectives. The 'meta-cognitive' knowledge was increased. 'Remember' of the 'cognitive process' dimension was decreased and the high level objectives as 'analyze' and 'create', in the 'cognitive process' dimension was increased from the 7th to the revised curriculum. The 'factual' knowledge, 'conceptual' knowledge and 'metacognitive' knowledge were engaged with 'understand' and the 'procedural' knowledge were engaged with 'apply'. The 'meta- cognitive' were engaged with 'create' is the 'procedural' knowledge in the revised Wise Life 2007. 'Remember' was decreased. 'Create' was increased in the basic inquiry activities. It was analysed in zero percent of 'Observing', 'Investigating and Presenting', and 'Making'.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.325-328
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• 2004

This paper deals with void crushing behavior by ingot forging process which consists of sequential operations of upset forging and bloom forging. The predicted results of void crushing behavior by the simplified global-local method using F.E. analysis showed that the inherent void at the top region of the ingots remains incompletely crushed even after several forging operations. From the results of the hot upset forging test using the billets with drilled voids, it was found that the bonding efficiency of the void after forging process increases with an increase in deformation, and a decrease of initial diameter of voids.

• Journal of Korean Society on Water Environment
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• v.29 no.5
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• pp.641-647
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• 2013

We installed mesocosms including zooplankton, fishs, artificial marshy land and aquatic macrophytes in Kyoungan stream to study the reduction effects of algae from Sep. 16 to Oct. 28, 2011. The control tendency of phytoplankton taxa was compared by analyzing community structure and dominant species in each mesocosm. Under the condition where Bluegill was absent, Daphnia similoides showed good effect of algal control since it has large food area and has high grazing pressure. Bluegill selectively preys upon large zooplankton, Daphnia similoides, as it also preys on small zooplanktons that flow in. In condition that Bluegill was absent, Daphnia similoides preyed selectively large phytoplankton (Cryptomonas ovata). Due to the shading of light, removal of nutrients and providing refuge for small zooplanktons, aquatic macrophytes and artificial marshy land showed high level of algal control. In corrals with aquatic macrophytes and artificial marshy land, the dominancy of genus Coelastrum and Pediastrum, which are difficult for small zooplanktons to feed on, relatively increased. In conclusion, under conditions of small number of predators such as Bluegill, Daphnia similoides is thought to be useful in algal bloom; however, when lots of predators are present, using small sized zooplanktons along with artificial marshy land and aquatic macrophytes is thought to be more useful than using large zooplanktons.