• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.43-52
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• 2011

The characteristics of shear zone in granular soils largely affect the stability of geo-structures. The goal of this study is to evaluate shear zone in a direct shear test using shear wave, electrical resistivity, and cone tip resistance. Bender elements and electrical resistivity probe are embedded into the wall of a direct shear box made of transparent acrylic material to estimate the shear wave velocities and the electrical resistivity at shear and non-shear zones. At the point of peak and residual strength, micro cone penetration test which can be available to measure tip resistance has been performed. Experimental results show that the shear wave velocities at upper shear zone increase during shearing while the values remain constant at bottom and lower shear zone. Also, resistivities at lower shear zone depend on relative density while resistivities at bottom remain constant. The results of cone penetration test demonstrate the correlation of the cone tip resistance and small strain shear modulus at shear zone. This study suggests that the application of the modified direct shear box including shear wave, electrical resistivity and the micro cone tip resistance may become effective tools for analyzing the characteristics of a shear zone.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.111-122
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• 2009

Dissolution of some of geo-materials may yield the loss of the soil strength and the settlement of earth structures. The goal of this study is to monitor the several physical behaviors of soluble mixtures during dissolution. Sand-salt mixtures are used to monitor the meso to macro response including the settlements and shear waves. The mixtures of photoelastic and ice disks are used to monitor micro to meso behavior of soluble mixture including the void ratio, force chain, coordination number and horizontal force changes. In the sand-salt mixtures, shear waves are measured by using bender elements in conventional oedometer cells. In the photoelastic disk - ice disk mixtures, micro to meso response are measured by digital images and load cells. The shear wave velocity decreases at the initial stage of the dissolution, and then increases and approaches to asymptotic value. The larger dissoluble particle and the more random packing produces the severe horizontal fore change. After dissolution, the void increases and the coordination number decreases. This study demonstrates that the particle level behavior such as the changes of the force chain, void ratio, and coordination number affects the global behavior such as the change of the shear wave velocity and horizontal force of the system.

• Asian Journal of Atmospheric Environment
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• v.6 no.2
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• pp.73-82
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• 2012

This study was aimed to thoroughly estimate the characteristics of indoor particulate matter (PM) collected on subway platforms by the cooperative approach of semi-bulk and single particle analyses. The size-resolved PM and its number concentration were measured on the platform in a heavily traveled subway station in Fukuoka, Japan. Particle Induced X-ray Emission (PIXE) and micro-PIXE techniques were applied to the chemical analyses of semi-bulk and single particle, respectively. There was the close resemblance of timely fluctuation between PM number concentration and train service on the third basement floor (B3F) platform compared to the second basement floor (B2F) and its maximum level was marked in rush hour. Higher number counts in large particles ($>1{\mu}m$) and lower number counts in fine particles ($<1{\mu}m$) were shown on the platform compared to an above ground. PM2.5 accounted for 58.2% and 38.2 % of TSP on B3F and on B2F, respectively. The elements that were ranked at high concentration in size-resolved semi-bulk PM were Fe, Si, Ca, S, and Na. The major elements tending to have more elevated levels on B3F than B2F were Fe (4.4 times), Ca (17.3 times), and Si (46.4 times). Although concentrations were very low, Cr ($11.9ng\;m^{-3}$ on B3F, $2.4ng\;m^{-3}$ on B2F), Mn ($3.4ng\;m^{-3}$ on B3F, $0.9ng\;m^{-3}$ on B2F), and Pb ($0.6ng\;m^{-3}$ on B3F, $1.6ng\;m^{-3}$ on B2F) were detected from PM2.5. Individual PM was nearly all enriched in Fe with Si and Ca. Classifying and source profiling of the individual particles by elemental maps and particle morphology were tried and particles were presumably divided into four groups (i.e., train/rail friction, train-rail sparking, ballast/abrasive, and cement).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.1
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• pp.49-59
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• 1995

Nine species of edible seaweed [green laver (Monostroma nitidium) and sea staghorn ( Codium fragile) of green algae; sea mustard (Undaria pinnatifida), seaweed fusiforme(Hizikia fusiforme), gulf weed (Sargassum fulvellium), and sea tangle (Laminaria japonica) of brown algae; seaweed dilatata (Halimeniopsis dilatata), seaweed furcata (Gloiopeltis furcata), and laver (Porphyra tenera) of red algae] collected from Kijang, Chungmu, and Yosu in Korea, were examined and compared on their chemical and mineral composition depending on their harvesting season. Crude protein $(N\pm6.25)$ showed about $45\%$ on moisture free basis (the contents of every components described below are shown as moisture free basis) for laver and $30\%$ for green laver collected from ever seasons and sites. Sea tangle showed the highest content in crude lipid $(10\%)$ among brown seaweeds and green laver had $6\%$ of crude lipid regardless their habitats. Ash and carbohydrate in sea staghorn hold about $90\%$ of total solids but those levels were only $50\%$ in laver. The relationship between ash and carbohydrate content showed a tendency with reverse correlation. Mineral compositions were examined on green laver, sea mustard, and seaweed furcata collected from Kijang. Sodium was eminent element (1,798-7,334mg/l00g) followed by potassium. Magnesium and calcium content were low level compared with sodium and potassium. As a micro-element iron was appraised the highest status (165-330mg/100g) in green laver, however, iron in sea mustard and seaweed furcata was comparatively low amount (2.7-47.4mg/100g). The level of zinc was also comparatively high and that was varied on habitats. In conclusion, chemical compositions of these algae were distinctively varied on species and habitats, and mineral compositions were notably changed by the harvesting season.

• Journal of Conservation Science
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• v.17 s.17
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• pp.39-56
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• 2005

The Gwangtonggyo(bridge) on the Cheonggyecheon(river) is mainly composed of biotite granite with coarse grain. The rock consists mainly of quartz, plagioclase, microcline, orthoclase and biotite with lesser amount of muscovite, sericite and chlorite. Muscovite and sericite may be formed from feldspars and chlorite from biotite by alteration(including weathering). These rocks are relatively deteriorated by weathering, polluted water running the river and heavy traffic. The main phenomena of damages are surface exfoliation, grain separation, deceleration, pollution of organic and heavy chemical elements, cracks and breakage. These phenomena have been analyzed by polarized microscope, XRD and SEM/EDX. The analyzed results show organic pollution and secondarily formed gypsum and apatite on the rock surface and micro-pores. NaCl and $CaCO_3$ as rock salt and calcite probably may be formed secondarily in some points. Also heavy chemical elements such as Cr, Pb, Pd, W, La, Zn and Nd are polluted in some samples. The contacts between rocks are generally breakdown in small scale or cracks are developed due to mainly load and vibration shock of heavy traffic.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1087-1093
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• 2014

Stainless steels stabilized with Ti or Nb are largely used in offshore and shipbuilding industries due to its excellent corrosion resistance. In this study, carbide stabilizers, Ti and Nb, were added to stainless steel 304 specimens with different concentrations(Ti: 0.26%, 0.71%, Nb: 0.29%, 0.46%, 0.71%), and their mechanical and electrochemical characteristics were evaluated. Micro-Vickers hardness testing was employed to characterize the mechanical characteristics with alloying elements. Electrochemical evaluation techniques including Tafel analysis, cyclic polarization experiment, galvanostatic experiment were utilized to compare the corrosion characteristics of the specimens. The result of hardness tests revealed that Nb containing specimens showed increasing hardness with increasing alloying contents while adding Ti had little effect on increase in hardness. In the case of electrochemical measurements, the electrochemical characteristics of the specimens were enhanced with increasing Nb contents while they were deteriorated with increasing Ti contents. As a result, different stabilizers and their contents may produce significant differences in electrochemical characteristics, and there such effect must be taken account of in development of stainless steels for marine environment.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.5 no.2
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• pp.24-30
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• 1999

The migration mechanism of trace elements, Pb, Cd, Cu, Zn and Sn from brass food-contact utensiles was investigated. The migration of metals from brass was affected by the migration temperature (30, 60, 80 and $95^{\circ}C$), the simulant pH (2.5, 4.3, 6.0 and 7.0) and the migration time (30, 90, 180 and 360 min.). The amount of Pb migration was maximum at $95^{\circ}C$ with pH 2.5. This study indicated that the equilibrium of Pb migration was reached at 180 minutes. The mechanism of Pb migration was investigated with Scanning Electron Microscope (SEM) and Electron Probe Micro Analyzer (EPMA). To correlate the relations between the migration and the content of Pb in brass samples, ten brass samples having known content of Pb (the quantities of Pb in brass ; 0, 0.02, 0.09, 0.1, 0.2, 0.5, 0.9, 1.4, 5.4 and 9.2% (w/w)) were tested in the following conditions, 4% acetic acid, $95^{\circ}C$ and 30 minutes. The result represented that content of Pb in brass samples must be below 0.2% (w/w) to satisfy the 1.0 ppm (as Pb) of Korea Food Code.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.3
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• pp.207-216
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• 2015

The study was conducted to determine the effects of forest restoration methods and stand structure on solar radiation, air temperature, relative humidity, soil temperature, and soil water content, based on volume, in forest stand after forest fire. The changes of the micro-climate elements in naturally and artificially restored forest after forest fire were measured in Goseong and Samcheok, Gangwon province. Pinus spp. were commonly appeared in ridges, barren lands or planted areas of the study sites while the other areas were dominated by Quercus spp. In the early stage, trees in the naturally regenerated site grow better than the trees in artificially rehabilitated site. However, the growth ratio rapidly decreased by time passed in natural regeneration area. The environmental conditions (solar radiation, air temperature, relative humidity, soil temperature and soil water content) were significantly different by the regions and the methods (p<.05). However, the coefficients of variations of the environmental conditions were not significantly different at 95% confidence level. As the coverage and tree height in crown layer increased, the relative humidity and soil water content were increased while the temperature and solar radiation were decreased. Especially, the relative humidity, solar radiation, and soil water content were clearly affected by the tree height and coverage ratio ($R^2$ means from 0.628 to 0.924). Even though the data should have collected at least more than 5 years in meteorological analysis, the two year results show some clear relationship between forest structure and microclimate elements.

• Journal of Life Science
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• v.26 no.7
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• pp.855-867
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• 2016

The horse is relatively earlier domesticated animal species. Domesticated horses have been selected for their ability of racing, robustness, and disease-resistance. As a result, the thoroughbred horse genome has been condensed many genotypes related to exercise ability. In recent years, with the advent of NGS technologies, many studies were concentrated on finding superior genetic species in the horse genome in terms of genomics. Consequently, GWAS (Genome-wide Association study) is applied to horse genome, then genetic marker is revealed for superior racing ability. In addition, RNA-Seq is utilized as a method for analyze of whole transcript profiling in specific samples. By using this approach, specific gene expression patterns and transcript sequences can be revealed in various samples such as each individual, before and after exercise state, and each tissue. DNA methylation, a strong factor that regulate gene expression without the change of DNA sequence, have got a lot of attention. In horse genome, exercise- or individual-specific DNA methylation patterns were detected, and could be useful to develop selective marker of superior horses. MicroRNAs inhibit gene expression, and transposable elements accounted for half of the mammalian genome. These two elements are the crucial factors in functional genomics, and could be applied to the selection of superior horses. As the functional genomics and epigenomics advance, then these technologies introduced in this paper were applied to select superior horses. In this paper, the studies for selection of superior horses through genetic technologies, and development possibilities of these studies were discussed.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.4
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• pp.215-220
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• 1980

This is a review of the theory and practical uses of the $Hom{\grave{e}}s$' systematic variations in the fertilizer experiments. General characteristics of the method are as follows : 1 ) It could be recommended as a reasonable met hod for fertilizer experiments in order to improve the weak points in the conventional methods. 2 ) This met hod is a determination of the total amount of nutrients and the relative proportion of each nutrient in the total. 3 ) Concerning of the high yields of crops this met hod should be adapted for the systematic fertilization. 4 ) This is an usable method not only for the macro- but also micro elements investigations.