• Journal of the Mineralogical Society of Korea
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• v.27 no.3
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• pp.159-168
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• 2014

Holocene plaeoenvironmental changes were interpreted by grain size and mineral analyses of a piston core (HB 13-2), obtained along the western slope of the Hupo Basin, Korea. The core sediments are characterized by two discrete, sedimentary facies: upper unit (0-0.4 mbsf) dominated by bioturbation structures with weak lamination, and lower unit (0.4-3.3 mbsf) characterized by intensified bioturbation toward bottom. Analysis of sensitive grain size and sortable silt demonstrated that the inflow of the Tsushima Warm Current (TWC) into the Hupo Basin strengthen from the period of sediment deposition over 0.82 mbsf. The minerals of the core sediments are composed mainly of quartz, microcline, orthoclase, albite and clay minerals including chlorite, kaolinite and illite. No noticeable changes of the mineral percentage was observed according to the grain size and depth of the samples. The integral breadth (${\Delta}^{\circ}2{\theta}$) of clay minerals from 1.4 mbsf to top layer shows an increasing trend, which clearly means climate warming from the period of sediment deposition above 1.4 mbsf. This interval correlates with the Holocene climate optimum at Mid Holocene.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.4
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• pp.196-203
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• 2004

To understand the geochemical processes in the Han River Estuary, distributions and behaviors of nutrients, dissolved organic matters, and uranium were investigated and analyzed during estuarine tidal mixing in June 2000 and February 2001. The distribution of inorganic nutrients showed very dynamic distributional patterns implying an apparent nitrification process and a concave non-conservative mixing along the salinity gradient. Dissolved organic carbon was high in the upstream region and decreased sharply in the low salinity region of around 5 psu. The 3-D fluorescence characteristic of dissolved organic matter showed two distinct fluorophores in the study area. Biomacromolecules originated mainly from the indigenous biochemical processes and geomacromolecules from terrestrial humic materials. In the study area, the distribution of geomacromolecule showed a concave non-conservative property along the salinity gradient presumably due to the flocculation and removal processes in the estuary. Meanwhile, distribution of the dissolved uranium, mainly in the form of stable uranium carbonate complex, also showed a concave non-conservative property along the salinity gradient in the Han River Estuary. From this study, the removal rate of dissolved uranium in the Han River Estuary was estimated to be about 7.1 ton per year.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.605-612
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• 2012

Spalling of concrete occurs due to vapor pressure ignited explosion, temperature difference across a section, and combination of these factors. Factors affecting spalling can be classified into internal and external factors such as material property and environmental condition, respectively, have to be considered to precisely understand spalling behavior. An external environmental factor such as differences in heating rate cause internal humidity cohesion and different vapor pressure behavior. Therefore, spalling property, vapor pressure and thermal strain property were measured from concrete with compressive strengths of 30 MPa, 50 MPa, 70 MPa, 90 MPa, and 110 MPa, applied with ISO-834 standard heating curve of $1^{\circ}C/min$ heating rate. The experimental results showed that spalling occurred when rapid heating condition was applied. Also, when concrete strength was higher, the more cross section loss from spalling occurred. Also, spalling property is influenced by first pressure cancellation effect of thermal expansion caused by vapor pressure and heating rates.

• Korean Security Journal
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• no.32
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• pp.123-150
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• 2012

The purpose of this study was to seek practical intelligences for certain persons who wish to be a guard by studying for what practical public guards' recognition of organization and vocation is. The results of this study were as follows. First, Six study participants presented 'Respect within members', 'Atmosphere like family', 'Premium members', and 'Economic compensation & wealth of budget' as essential requirements for the best guard organization. Second, they also presented 'Systematic daily task & training', 'Exact selection system', and 'Strong cohesion & teamwork' as strong points of their organization. Third, they mentioned 'Internal evaluation system', 'Lack of education contents', and 'Limited position circulation' as weak points of their organization. Fourth, they mentioned that they feel encouraged itself as they work in the best guard organization, while they were skeptical when the citizens did not cooperate with them and they were not fully rewarded for their injury. Fifth, they expressed 'Difficulty of business cooperation', 'Unstable living patterns', 'Inconsistent assessment', and 'Continuing tension' as difficulties for performing the duties and stress causes. Lastly, they recognized of job security and self-esteem as they work in the best guard organization as advantages of a job, while they recognized of controlled life, low salaries and welfare level compared to duty importance and risks as disadvantages of a job. Consequently, students who wish to be a guard should consider job and organization attributes and set their career goals refer to these results.

• Journal of the Korean Vacuum Society
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• v.17 no.5
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• pp.466-472
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• 2008

Purple Gold is the alloy consisting of 78wt%Au-22wt%Al, and is expressed as a chemical formula, $AuAl_2$. Lately it is being used for the material of accessories or the decorative ornaments, being one of the colored golds having the peculiar purple color, like White Gold and Pink Gold. Purple Gold has the weak point in shaping through casting process due to the bad malleability and castability, being the intermetalic compound of Au and Al. Therefore, it is possible to produce the final product only by the cutting and the grinding process or to use it as a decorative coat with the thin film evaporation. This study implemented two kinds of thin film experiments. One is the case that heat treatment was made after Au and Al deposition evaporated separately with a weight ratio 78:22 on the 200nm$SiO_2$/Si substrate. The other is the case that the surface deposition was made through the vacuum evaporation, keeping the glass substrate temperature remain room temperature, using the bulk $AuAl_2$ as a source. The final film property was measured, focusing on the Purple Gold's color and thickness through the bare eye inspection, the microstructure analysis, the surface resistance analysis, the color difference analysis, and XRD analysis. Purple Gold was not formed, as the excessive surface agglomeration occurred, in case of being produced and treated thermally with 12.5nmAu/40nmAl/200nm$SiO_2$/Si structure. Our results suggest that of Purple Gold films, showing the same purple color as the bulk's, were successfully deposited with the direct thermal evaporation from the $AuAl_2$ bulk source.

• Korean Journal of Microbiology
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• v.38 no.1
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• pp.26-30
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• 2002

A ubiquitous bacterium,Effects of Lead, Copper and Cadmium on Pseudomonas cepacia KH410 Isolated from Freshwater Plant Root was isolated from freshwater plant root and interactions of lead, copper and cadmium with this strain was studied. Mass production of dry cell weight 2.72 g-DCW/ι-medium was obtained by cultivation in a nutrient medium containing 1% yeast extract, 1% soytone and 0.5% NaCl, pH 7.0, at temperature of 28℃ for 24 hrs under aeration. The mass of dry cell produced after exposure with 100 mg/ι of heavy metal was 1.98 g/ι for lead, 1.58 g/ι for copper and 0.20 g/ι for cadmium, respectively. The minimal inhibitory concentrations (MIC) for each heavy metal was 1.3 mM for lead,0.8 mM for copper and 0.4 mM fur cadmium, respectively. Cell aggregation occurred by each heavy metal exposure was observed from 1 day to 4 days by an optical microscope. Entrapment, precipitation effects on cell by heavy metals between 10 min and two hours were examined by an electron microscopy. Cadmium appeared to be the most toxic on cells and the order of toxicity was cadmium>copper>lead.

• Korean Journal of Environmental Agriculture
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• v.21 no.2
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• pp.130-135
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• 2002

Water-dispersible colloids are suspected to facilitate transport of contaminants to groundwater. This study evaluated some soil chemical properties in relation to the stability of colloids in soils of Jeju citrus orchards. Thirty surface soil samples were collected, and pH, organic matter content oxalate-extractable Al and Fe contents, and water-dispersible colloid content were measured. In soils of higher pH, water-dispersible colloid contents were higher. The stability of colloids was found to be significantly promoted at pH above 5$\sim$6. Since organic matter can act as a flocculant organic matter content significantly enhanced the colloid stability. In soils of less than 5% organic C, water-dispersible colloid content was expected to be significantly higher. In soils of higher oxalate-extractable Al and Fe contents, colloids remaining in suspension were lower. This indicated that amorphous oxides and hydroxides play important stabilizing roles in soil structure and can stabilize soil clay against dispersion. Therefore in soils of higher pH, lower organic matter, and lower amorphous clay minerals, the stability of water-dispersible colloids and the potential of colloid-mediated transport of organic chemicals to groundwater could be higher.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.311-316
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• 2010

This study aimed to prepare antimony-doped tin oxide (ATO) dispersion with high stability. The methods to achieve this goal were sought by investigating the changes of ATO particle size, size distribution, dispersion property as wet ball milling treatment time increased. And the changes of wet ball milled ATO dispersion property were also investigated, as pH increased. The changes of ATO particle size and size distribution, according to wet ball milling treatment time were evaluated with laser diffraction particle size analyzer and scanning electron microscope (SEM). The changes of ATO dispersion property, as wet ball milling treatment time and pH increased, were evaluated with zeta potential analysis and Turbiscan. By 60 min wet ball milling treatment time, ATO particle size decreased and size distribution became narrower, as the treatment time increased. After 60 min milling, the ATO particle size decreased to less than 30% of the initial size and the size distribution was narrowed to $0.1{\sim}5{\mu}m$ from $1{\sim}35{\mu}m$. However, more than 60 min milling, ATO particles aggregated and the particle size increased. ATO dispersion stability also increased as the treatment time and pH increased because the reduced particle size increased particle surface energy and repulsion between particles and the increased pH enhanced particle surface ionization. Hence, after proper length of wet ball milling treatment, highly stable ATO dispersion can be prepared, as increasing pH of the dispersion.

• Korean Journal of Food Science and Technology
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• v.47 no.3
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• pp.293-298
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• 2015

This study aimed at characterizing the rheological properties and molecular weight of tara gum fractionated with ammonium sulfate. Tara gum was separated into six fractions (F1-F6) at different concentrations of ammonium sulfate, ranging from 12.21 to 28.67% (w/w). The yield of the tara gum fractions ranged between 4.98 and 17.47%, and their intrinsic viscosity ranged from 9.38 to 12.44 dL/g. The highest values of Huggins coefficient (k') and viscosity-molecular mass were observed in fraction F3. The shear viscosity of the tara gum fractions was measured by a cone-plate viscometer, clearly showing shear thinning behavior. Size-exclusion chromatography results showed that the molecular weight ranged between 635.42 and 776.71 kg/mol, and the F3 fraction exhibited higher values of molecular weight.

• Korean Journal of Food Science and Technology
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• v.49 no.5
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• pp.494-501
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• 2017

Waffles with cinnamon powder added in different proportions (0-12% of wheat flour) were baked to investigate the effects of baking on the physicochemical properties and antioxidant activity. Compared with the control without cinnamon, baking loss was lower in waffles with cinnamon, which led to a decrease in waffle hardness. This was attributable to the higher water-holding capacity of cinnamon than wheat flour. With the increase in the amount of cinnamon, the springiness, resilience, and cohesiveness of the waffle decreased, which was thought to result from the decrease in gluten formation by the proportional decrease of wheat flour. The total reducing capacity and DPPH radical scavenging activity of the waffle was significantly increased. This was substantially in agreement with the observations that cinnamon had an appreciable total reducing capacity and radical scavenging activity that were unchanged by heat treatment. This indicates that the antioxidant functionality of cinnamon could be effectively added to thermally processed food.