• Korean Journal of Heritage: History & Science
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• v.50 no.4
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• pp.122-147
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• 2017

The Jungsandong sites are distributed across quartz and mica schist formations in Precambrian, and weathering layers include large amounts of non-plastic minerals such as mica, quartz, felspar, amphibole, chlorite and so on, which form the ground of the site. Neolithic pottery from Jungsandong exhibits various brown colors, and black core is developed along the inner part for some samples, and sharp comb-pattern and hand pressure marks can be observed. Their non-plastic particles have various composition, size distribution, sorting and roundness, so they are classified into four types by their characteristic mineral compositions. I-type (feldspar pottery) is including feldspar as the pain component or mica and quartz. II-type (mica pottery) is the combination of chloritized mica, talc, tremolite and diopside. III-type (talc pottery) is with a very small amount of quartz and mica. IV-type (asbestos pottery) is containing tremolite and a very small amount of talc. The inner and outer colors of Jungsandong pottery are somewhat heterogeneous. I-type pottery group shows differences in red and yellow degree, depending on the content of feldspar, and is similar to III-type pottery. II-type is similar to IV-type, because its red degree is somewhat high. The soil of the site is higher in red and yellow degree than pottery from it. The magnetic susceptibility has very wide range of 0.088 to 7.360(${\times}10^{-3}$ SI unit), but is differentiated according to minerals, main components in each type. The ranges of bulk density and absorption ratio of pottery seem to be 1.6 to 1.7 and 13.1 to 26.0%, respectively. Each type of pottery shows distinct section difference, as porosity and absorption ratio increase in the order as follows: I-type (organic matter fixed sample) < III-type and IV-type < I-type < II-type (including IV-type of IJP-15). The reason is that differences in physical property occur according to kind and size of non-plastic particles. Although Jungsandong pottery consists of mixtures of various materials, the site pottery has a geological condition on which all mineral composition of Jungsandong pottery can be provided. There, it is thought that raw materials can be supplied from weathered zone of quartz and mica schist, around the site. However, different constituent minerals, size and rock fragments are shown, suggesting the possibility that there can be more raw material pits. Thus, it is estimated that there may be difference in clay and weathering degree.

• Journal of the Korean Geotechnical Society
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• v.29 no.4
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• pp.45-56
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• 2013

In this study, a blast furnace slag with latent hydraulic property is used to cement granular soils without using Portland cement. When the blast furnace slag reacts with an alkaline activator, it can cement soils. The effect of amounts of blast furnace slag and types of alkaline activator on soil strength was investigated for resource recycling. Four different amounts of slag and six different activators (two naturals and four chemicals) were used for preparing specimens. The specimens were air-cured for 3 or 7 days and then tested for unconfined compressive strength (UCS). The UCS of cemented sand with slag increased, in the order of specimens mixed with potassium carbonate, calcium hydroxide, sodium hydroxide and potassium hydroxide. Chemical alkaline activator was better than natural alkaline activator. The maximum UCS of 3-days cured specimens was 3 MPa for 16% of slag with potassium hydroxide, which corresponded to 37% of one with 16% of high-early strength portland cement. As the amount of slag increased, the UCS and dry density of a specimen increased for all alkaline activator cases. As the curing time increased from 3 days to 7 days, the UCS increased up to 97%. C-S-H hydrates were found in the cemented specimens from XRD analyses. Cement hydrates were more generated with increasing amount of slag and they surrounded sand particles, which resulted in higher density.

• Journal of the Korean Geotechnical Society
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• v.30 no.2
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• pp.19-32
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• 2014

Carbonate sand of Sabkha layer in the middle east was made of deposition of shell fragments and it consisted of porous particles containing inner void. Generally, at yield stress the soil structure begins to break down, so the porewater pressure and the settlement are increased rapidly. In carbonate sand, unlike quartz sand if particle crushing happens, the inner voids are exposed and porewater pressure can be decreased under yield stress. Porewater pressure can be determined as the sum of excess porewater pressure due to increase of relative density, inner void expose of particle under particle crushing stress and rearrangement of crushed particle fragments. The porewater pressure can be negative value in case of greater amount of inner void expose, so if particle crushing is bigger, the porewater pressure value is smaller. The negative value zone of porewater pressure from triaxial test result means particle crushing effect is bigger than outer void decrease effect and the particle crushing effect dominant zone size was 1.50∼3.46% from triaxial test result of Sabkha layer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.3
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• pp.359-366
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• 1993

Molds are eucaryotic, multicellular, multinucleate, filamentous organisms that reproduce by forming asexual and sexual spores. The spores are readily spread through the air and because they are very light-weight and tend to behave like dust particles, they are easily disseminated on air currents. Molds therefore are ubiquitous organisms that are found everywhere, throughout the environment. The natural habitat of most molds is the soil where they grow on and break down decaying vegetable matter. Thus, where there is decaying organic matter in an area, there are often high numbers of mold spores in the atmosphere of the environment. Molds are common contaminants of plant materials, including grains and seeds, and therefore readily contaminate human foods and animal feeds. Molds can tolerate relatively harsh environments and adapt to more severe stresses than most microorganisms. They require less available moisture for growth than bacteria and yeasts and can grow on substrates containing concentrations of sugar or salt that bacteria can not tolerate. Most molds are highly aerobic, requiring oxygen for growth. Molds grow over a wide temperature range, but few can grow at extremely high temperatures. Molds have simple nutritional requirements, requiring primarily a source of carbon and simple organic nitrogen. Because of this, molds can grow on many foods and feed materials and cause spoilage and deterioration. Some molds ran produce toxic substances known as mycotoxins, which are toxic to humans and animals. Mold growth in foods can be controlled by manipulating factors such as atmosphere, moisture content, water activity, relative humidity and temperature. The presence of other microorganisms tends to restrict mold growth, especially if conditions are favorable for growth of bacteria or yeasts. Certain chemicals in the substrate may also inhibit mold growth. These may be naturally occurring or added for the purpose of preservation. Only a relatively few of the approximately 100,000 different species of fungi are involved in the deterioration of food and agricultural commodities and production of mycotoxins. Deteriorative and toxic mold species are found primarily in the genera Aspergillus, Penicillium, Fusarium, Alternaria, Trichothecium, Trichoderma, Rhizopus, Mucor and Cladosporium. While many molds can be observed as surface growth on foods, they also often occur as internal contaminants of nuts, seeds and grains. Mold deterioration of foods and agricultural commodities is a serious problem world-wide. However, molds also pose hazards to human and animal health in the form of mycotoxins, as infectious agents and as respiratory irritants and allergens. Thus, molds are involved in a number of human and animal diseases with serious implication for health.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.567-580
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• 2010

Organic carbon (OC) and elemental carbon (EC) concentrations were determined for $PM_{10}$, $PM_{2.5}$ and $PM_{1.0}$ aerosols particles collected at Gosan Superstation on Jeju Island from August 2007 to September 2008. Aerosols were collected on quartz filters for 24 hours and then OC and EC were analyzed by TOR/IMPROVED method. Mean concentrations of OC and EC were $4.66\;{\mu}g/m^3$ and $1.69\;{\mu}g/m^3$ for $PM_{10}$, $3.95\;{\mu}g/m^3$ and $1.69\;{\mu}g/m^3$ for $PM_{2.5}$, and $3.16\;{\mu}g/m^3$ and $1.42\;{\mu}g/m^3$ for $PM_{1.0}$, respectively. The concentrations of OC and EC comprised 16.4% and 6.0% of $PM_{10}$, 22.9% and 9.8% of $PM_{2.5}$, and 23.0% and 10.0% of $PM_{1.0}$. OC and EC showed a clear seasonal variation with the highest in winter and the lowest in summer. The correlations between the two were also the best during the winter ($R^2$=0.87, 0.94, and 0.95 for $PM_{10}$, $PM_{2.5}$ and $PM_{1.0}$). The ratio of OC/EC exhibited the maximum (7.24) during an Asian dust event due to an increase of OC, which was possibly derived from soil. The mass fraction of both OC and EC was the highest in fall. When OC and EC concentrations were highly elevated, EC1 (the first EC fraction determined at $550^{\circ}C$) and pyrolyzed OC (POC) were dominant subcomponents in winter and OC3 (the third OC fraction determined at $450^{\circ}C$) and POC in spring.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.439-454
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• 2008

The purpose of this study was to extensively identify $PM_{10}$ sources and to estimate their contributions to the study area, based on the analysis of the $PM_{10}$ mass concentration and the associated inorganic elements, ions, and total carbon. The contribution of $PM_{10}$ sources was estimated by applying a receptor method because identifying air emission sources were effective way to control the ambient air quality. $PM_{10}$ particles were collected from May to November 2007 in the Yongin-Suwon bordering area. $PM_{10}$ samples were collected on quartz filters by a $PM_{10}$ high-volume air sampler. The inorganic elements (Al, Mn, V, Cr, Fe, Ni, Cu, Zn, Cd, Pb, Si, Ba, Ti and Ag) were analyzed by an ICP-AES after proper pre-treatments of each sample. The ionic components of these $PM_{10}$ samples ($Cl^_$, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $NH_4^+$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$) were analyzed by an IC. The carbon components (OC1, OC2, OC3, OC4, OP, EC1, EC2 and EC3) were also analyzed by DRI/OGC analyzer. Source apportionment of $PM_{10}$ was performed using a positive matrix factorization (PMF) model. After performing PMF modeling, a total of 8 sources were identified and their contribution were estimated. Contributions from each emission source were as follows: 13.8% from oil combustion and industrial related source, 25.4% from soil source, 22.1% from secondary sulfate, 12.3% from secondary nitrate, 17.7% from auto emission including diesel (12.1%) and gasoline (5.6%), 3.1% from waste incineration and 5.6% from Na-rich source. This study provides information on the major sources affecting air quality in the receptor site, and therefore it will help us maintain and manage the ambient air quality in the Yongin-Suwon bordering area by establishing reliable control strategies for the related sources.

• Geotechnical Engineering
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• v.14 no.6
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• pp.113-125
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• 1998

At the end of 1997 about 3 million tons of coal ash was produced as byproducts from the coal fired electrical power plants in Korea. Only about 27% of that byproducts was utilized as the admixtures of cement and concrete industry. But the large quantity of coal fired fly-ash has been used as the soil improvement materials in other countries. So the aim of this study is the estimation of the applicability of the coal fired fly-ash as microfine grouting materials by admixing the superfine particles which were separated from the coal fired fly-ash for the higher values. The 6 types of specimens were manufactured in the laboratory for the purpose of estimating the chemical and physical properties of cement and grouts. These specimens consisted of 2 specific surfaces of 6, 000 and 8, 000$cm^2$/g in Elaine method. And these specimens are devide into 3 ratios (30%, 50%, 70%) of fly-ash by weight. From the estimated properties of the coal fired fly-ash microflne cements and grouts, 50% fly-ash is the most suitable ratio for grouting materials. However, further study of durability is necessary for using fly-ash grouts practically at the field projects. The higher content of the unburned carbon of fly-ash increases the thinner layer of carbon on the surface of solution of grouts, and requires more quantity of surface active agent. As a results of this study, it is found that the microfine fly-ash is very useful as a good grouting material if 50% of fly-ash is added with the microfine portland cement. So, in the near future, if the coal fired fly-ash is able to be used as grouting material in Korea, the demand of fly-ash will increase rapidly.

• Journal of Environmental Science International
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• v.27 no.4
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• pp.241-250
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• 2018

The objective of this study was to estimate air quality trends in the study area by surveying monthly and seasonal concentration trends. To do this, the mass concentration of $PM_{10}$ samples and the metals, ions, and total carbon in the $PM_{10}$ were analyzed. The mean concentration of $PM_{10}$ was $33.9{\mu}g/m^3$. The composition of $PM_{10}$ was 39.2% ionic species, 5.1% metallic species, and 26.6% carbonic species (EC and OC). Ionic species, especially sulfate, ammonium, and nitrate, were the most abundant in the $PM_{10}$ and had a high correlation coefficient with $PM_{10}$. Seasonal variation of $PM_{10}$ showed a similar pattern to those of ionic and metallic species. with high concentration during the winter and spring seasons. $PM_{10}$ showed high correlation with the ionic species $NO_3{^-}$ and $NH_4{^+}$. In addition, $NH_4{^+}$ was highly correlated with $SO{_4}^{2-}$ and $NO_3{^-}$. We obtained four factors through factor analysis and determined the pollution sources using the United States Environmental Protection Agency(U.S. EPA) pollution profile. The first factor accounted for 51.1% of $PM_{10}$ from complex sources, that is, soil, motor vehicles, and secondary particles: the second factor indicated marine sources; the third factor, industry-related sources; and the last factor, heating-related sources. However, the pollution profile used in this study may be somewhat different from the actual situation in Korea because it was from US EPA. Therefore, to more accurately estimate the pollutants present, it is necessary to create a pollution profile for Korea.

• Journal of the Mineralogical Society of Korea
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• v.5 no.1
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• pp.14-21
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• 1992

Allanite crystals rich in rare-earth elements(REE) occur in soil developed on top of anorthositic rocks in the Jungsu-ri area of Okjong-myun, Hadong-run, where large Ti orebodies are embedded in the bed rock. In this study allanite is investigated mainly by transmitted light microscopy, electron microprobe analysis, atomic absoption spectrophotometry, X-ray diffraction, infrared spectrocopy. In addition, its specific gravity and micro=indentation hardness value are measured. Allanite occurs with max. dimension of $3cm{\times}6cm$ and coexists with quartz, epidote, zircon, biotite and muscovite. It shows nearly nonmetamict crystallinity, although ${\alpha}$-particles bombardment from the disintegration of the radioactive element Th is detected by an autoradiography. The allanite is particularly enriched in REE(19.88-23.99 wt.%), but is deficient in CaO(8.35-10.29wt.%). Genesis of the allanite in this area is not understood yet. It is, however, assumed to have been formed from magmatic fluid rich in REE and Ti, based on the facts that it ocexists with zircon and that it has high $TiO_2$(0.89-1.13 wt.%) whose concentration is significant in the country rocks.

• Korean Journal of Plant Resources
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• v.8 no.3
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• pp.237-246
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• 1995

In this study, the callus was induced and regenerated from the immature embryo and ultrastructural characteristics of developmental stages in Citrus junos SIEB, were investigated. The yellowish callus was induced by 5 to 6 week of culture of citrus. In proliferation callus after 6 weeks of culture, large vacuole was formed by fusion between adjacent small ones. In the non-embryogenic callus cultured for 12weeks, re-differentiated cells of callus showed the large nucleus with globular nucleus and amyloplast with large size of starches. In the embryogenic callus cltured for 14-16 weeks, the active exocytosis occurred in cells, secretory vesicles appeared on cell membrane and small particles from cytoplasm were released to intercelluar space. In the embryogenic callus cultured for 24 weeks, a sperical type of chloroplast bounded on cytoplasm by double membrane and typical grana was dispersed equally among matrix. In the normal plantlet after 26 weeks of culture, a lot of vessels and companion cells apperaed in the leaf cell of plantlet. In the normal plantlet after 30 weeks of culture, the immature leaf showed many small companion cells, sieve tubes and central vacuole. Also, the secondary vacuole protruded into the central vacuole and elongated chloroplasts near plasma membrane. In the matured plant habituated on the soil, palisada tissue composed of orderly arranged cells contained the nucleus in the center of the cell and large vacuoles on either side of the nucleus.