• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.143-148
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• 2004

Organic and inorganic substrates commonly used in Korea include peat moss, coir, bark, rice hull, saw dust, perlite, vermiculite, rockwool granulate, clay ball, and so on. The objective of this study was to get analytical results about the physical and chemical properties of these substrates by European standard methods. Organic substrates showed different properties depending on the type, origin and manufacturing processes. Inorganic substrates showed different properties depending on the type and particle size. Further study on physical and chemical properties for more raw materials and commercially available growing media analyzed by European standard method and comparison of the results with those by Korean standard method is needed.

• ALGAE
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• v.19 no.4
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• pp.329-337
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• 2004

Monthly variations of phytoplankton communities were conducted to the investigation at five stations in mid and lower parts of the Nakdong River from December 1995 to November 1996. The phytoplankton communities were identified a total 456taxa which were composed of 136 genera, 427 species, 27 varieties and 2 forma. The standing crops of phytoplankton communities ranged from 2.7 to 52.8 (${\times}$10³)cells·ml$^{-1}$ during the investigation periods. Bacillariophyceae was the dominant classes at all stations. The dominant species were 7taxa and the standing crops of these ranged from 18.3 to 95.1% of the standing crops of phytoplankton communities. The dominant species in the mid parts (st. 1, 2) of this river system were benthic species such as Navicula gregaria, N. viridula var. rostellata and Nitzschia palea, however it was planktonic species (Stephan discus hantzschii, Golenkinia radiata) and meroplanktonic species (Aulacoseira ambigua, A. granulata) in the lower parts (st. 3, 4, 5). The seasonal variations of the dominant species in the lower parts were appeared to the planktonic species (S. hantzschii) from winter to spring, and were the meroplanktonic species (A. ambigua and A. granulata) in from summer to fall. The lower parts of the Nakdong river were entropic states because the dominant species were composed A. ambigua, A. granulate and S. hantzschii which were indicators of entropic water quality. The interrelationships between total standing crops and environmental factors(water temperature, pH, NH$_4$, NO$_2$, NO$_3$ and PO$_4$) were low positive or negative coefficients. S. hantzschii had low positive or negative relations with water temperature, NH$_4$, NO$_2$, NO$_3$ and PO$_4$. As the result, the variations of standing crops of phytoplankton were not caused by a single factor but controlled by the complex factors.

• Journal of Powder Materials
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• v.13 no.5 s.58
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• pp.321-326
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• 2006

Electronic packaging involves interconnecting, powering, protecting, and cooling of semiconductor circuits fur the use in a variety of microelectronic applications. For microelectronic circuits, the main type of failure is thermal fatigue, owing to the different thermal expansion coefficients of semiconductor chips and packaging materials. Therefore, the search for matched coefficients of thermal expansion (CTE) of packaging materials in combination with a high thermal conductivity is the main task for developments of heat sink materials electronics, and good mechanical properties are also required. The aim of this work is to develop copper matrix composites reinforced with carbon nanofibers. The advantages of carbon nanofibers, especially the good thermal conductivity, are utlized to obtain a composite material having a thermal conductivity higher than 400 W/mK. The main challenge is to obtain a homogeneous dispersion of carbon nanofibers in copper. In this paper, a technology for obtaining a homogeneous mixture of copper and nanofibers will be presented and the microstructure and properties of consolidated samples will be discussed. In order to improve the bonding strength between copper and nanofibers, different alloying elements were added. The microstructure and the properties will be presented and the influence of interface modification will be discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1095-1104
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• 2014

This paper presents the results of experimental work on both strength characteristics and durability of concrete or mortar having 50% ground granulate blastfurnace slag(GBS) with different fineness levels (4,450, 6,000 and $8,000cm^2/g$). Compressive and split tensile strength test results indicated that the concrete with a higher fineness level of GBS exhibited a better strength development due to the acceleration of latent hydraulic property at the later curing stage compared with ordinary portland cement concrete. Meanwhile, it was found that a higher fineness level of GBS showed some negative effects on the resistance against freezing-thawing action. However, incorporation of GBS to concrete, irrespective of fineness levels, significantly enhanced the chloride ions penetration resistance. The resistance against sulfate attack of mortar with GBS was greatly dependent on the attacking sources from sulfate environments.

• Journal of Species Research
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• v.4 no.2
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• pp.159-168
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• 2015

Although airborne pollen is invisible to the eye, it has been known as a major source to respiratory allergic reactions. For this reason, airborne pollen is monitoring in many countries to predict pollen concentration based on locality and season. However, the morphological characteristics of airborne pollen and their potential tendency as an allergen are still obscure. In the present study, we selected 52 airborne pollen samples based on previously reported data and investigated their detail pollen characteristics using LM and SEM. Major airborne pollen in Korea has sorted in 19 families (most angiosperms except four gymnosperm families), and all pollen grains are small to medium in size ($P=17.34-49.86{\mu}m$) apart from the bisaccate pollen grains of Pinaceae ($P=46.49-106.20{\mu}m$). The aperture number and shape vary from sulcate to polyporate. While the inaperture pollen has found only in gymnosperm (Cupressaceae and Taxaceae), triporate or polyporate is common pollen type in angiosperm. The sexine ornamentations could divide into several types, but the most sculpturing types are inconspicuous like psilate, rugulate and granulate. Reticulate pollen grains as a semitectum have occurred the species of genera Platanus and Fraxinus only. To estimate the possible relationships between pollen features and allergen, the results are discussed in botanical context.

• Korean Journal of Plant Taxonomy
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• v.45 no.2
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• pp.183-191
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• 2015

The palynological characters of 14 taxa of 4 genera (Cynanchum, Metaplexis, Tylophora, Marsdenia) in Asclepiadoideae were observed and measured using SM and SEM. The orientation and granulate surface patterns of the pollinia were important characters for delimitating the genera. The position of the attachment of the translator arms to the pollinia, considered to be an important character for recognizing the above genera, was an overlapping character among the genera and can therefore be utilized only as taxonomy at the species level. Also, we found for the first time that only Tylophora floribunda has an incised margin of the corpusculum. The quantitative characters of the pollinia, arms and corpusculum were useful keys for the delimitation of the species.

• The Journal of the Korea Contents Association
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• v.10 no.7
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• pp.297-304
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• 2010

As Small Intestine Absorptive Epithelium Cells are surrounded by mucus polysaccharide and lymphocytes and mitochondria, they are sensitive to radiation energy. Damaged cells lead to a deficiency of nutrients and the imbalance of electrolyte metabolism, which in turn can becomes a major cause of an intestine tract death. This research observed ultra structures after injecting propolis into the abdominal cavity in order to reveal the radiation damage mechanism and radioprotection effect of intestine absorptive epithelium cells. The result of this research's observation found that stenosis occurred in the small intestine in some tissues 20 days after 5Gy irradiation, their surface turned black, and their elasticity dropped. Through observation with an optical microscope, it was found that the size of the goblet cells decreased, while the paneth granulate cells atrophied and were vacuolated. Observation with an transmission electron microscope(TEM) revealed that while microvill and lysosome were normally observed in jejunum tissues, mitochondria membrane was damaged and uneven surfaces were formed on lymphocytes. The membrane of absorptive epithelium cells hypertrophied in tissues of the ileum, and vacuole was observed. However, the observation after injecting propolis into the abdominal cavity found that mitochondria damage dropped dramatically, and radioprotection effects were to some extent confirmed, considering that glycocalyx of villi was clear, and M cells could be observed.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.2
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• pp.55-58
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• 2004

The objective of this study was to get information about water retention characteristics of horticultural substrates used in Korea determined by European standard method. Water retention curves were prepared at water volume (v/v, %) in relation to -10 cm, -50 cm, -100 cm water pressure head. Water retention curves showed different properties depending upon the type, the place of origin, particle size, and manufacturing processes of substrates. Peat and coir had easily available water content in the range of 30-40% and showed high water holding capacity, water buffering capacity, and aeration for plant growth. However, bark, sawdust and rice hull showed low water holding capacity about below 10%. The easily available water content of perlite and clay ball was low about 0.1-13.8%, whereas that of vermiculite and rockwool granulate was high about 25.9-52.0%. Understanding water retention characteristics of growing substrates is very important in cstablisliing optimum condition for plant growth. Further study on water retention curves for more substrates, mixture and growing media is needed.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.1-9
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• 2004

This paper represents the permeability of chloride ions and the corrosion performance in the concrete blended with granulate blast furnace slag exposed to chloride environment. An ordinary cement (type I ) and sulfate resisting cement(type V) were used for the experiment. The two cements were combined with $0\%$, $25 \%$, $40\%$, and $55\%$ of the granulated blast furnace slag. The accelerated permeability tests of chloride ions were performed in accordance with ASTM C1202, and the accelerated corrosion tests of steel were carried out by using the method of immersion/drying cycles. After water curing 28 days, 56 days and 91 days, these tests were conducted until 30 cycles. In every cycle, test specimens were wetted in $3\%$ NaCl solution for three days and dried again in $60^{\circ}C$ air for four days. As an experimental results, the diffusion coefficient of chloride ions of the ordinary cement Concrete Combined granulated blast furnace slag was much lower than that of non granulated blast furnace slag concrete. Moreover, the diffusion coefficient of chloride ions of sulfate resisting cement concrete was higher than that of ordinary cement concrete. On the basis of the results of accelerated corrosion tests, corrosion resistance of the concrete mixed with granulated blast furnace slag shows good to corrosion resistance, however, the concrete with sulfate resisting cement shows bad to corrosion resistance.

• Korean Journal of Soil Science and Fertilizer
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• v.15 no.3
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• pp.188-193
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• 1982

Granulation formed from mixture of sulfate of potash (SOP) powder and pulverized silica minerals (Zeolite, Serpentine and Talc) was studied to establish granulation rate and physical properties of granules. These mixtures were granulated in a pan granulator with water and granules of SOP were coated with minerals powder. Mixture of SOP and mineral powder by half (w/w) were increased granulation rate compared with pure SOP powder, and talc was superior to them with SOP. Water was needed about 14% to granulate SOP powder alone, but it decreased by 2% with talc and increased by 4% and 2% with zeolite and serpentine, respectively. Granules of mixture of SOP with zeolite were harder than pure SOP granules but with another minerals powder decreased in hardness. Also breaking rate of granules in vinyl parcel falling from 2m height and abrasion rate of granules by agitation were improved by mixing and coating with zeolite but with the other were of inferior.