• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.6
• /
• pp.374-385
• /
• 2013

Sediment particle motions have been numerically simulated over a sinusoidal ripple. Turbulent boundary layer flows are generated by Large Eddy Simulation, and the sediment particle motions are simulated using Lagrangian particle tracking method. Two unsteady flow conditions are used in the experiment by employing two different wave amplitudes while keeping other conditions such as wave period same. As expected, the amount of suspended sediment particles is clearly dependent on the wave amplitude as it is increasing with increasing flow intensity. However, it is also observed that the pattern of suspension may be different as well due to the only different condition caused by wave amplitude. Specially, the time of maximum sediment suspension within the wave period is not coincident between the two cases because sediment suspension is strongly affected by the existence of turbulent eddies that are formed at different times over the ripple between the two cases as well. The role of these turbulent eddies on sediment suspension is important as it is also confirmed in previous researches. However, it is also found the time of these eddies' formation may also dependent on the wave amplitude over rippled beds. Therefore, it has been proved that various flow as well as geometric conditions under waves has to be considered in order to have better understanding on the sediment suspension process over ripples. In addition, it is found that high turbulent energy and strong upward flow velocities occur during the time of eddy formation, which also supports high suspension rate at these time steps. The results indicate that the relationship between the structure of flows and bedforms has to be carefully examined in studying sediment suspension at coastal regions.

• Economic and Environmental Geology
• /
• v.34 no.6
• /
• pp.507-522
• /
• 2001

At the Tongyeong mine, quartz, rhodochrosite (kutnahorite), muscovite, illite, pyrite, galena, chalcopyrite. sphalerite, acanthite, and hessite are the principal vein minerals. They were deposited under epithermal conditions in two stages. Ore mineral assemblages and associated gangue phases in stage can be clearly divided into two general associations: an early cycle (band) that appeared with introduction of most of the sulfides and electrum, and a later cycle in which base metal and carbonate-bearing assemblages (mostly rhodochrosite) became dominant. Tellurides and some electrum occur as small rounded grains within subhedral-to euhedral pyrite or anhedral galena in stageII. Sulfide mineralization is zoned from pyrite to galena and sphalerite. We have used computer modeling to simulate formation of four stages of vein genesis. The reaction of a single fluid with andesite host rock at 28$0^{\circ}C$, isobaric cooling of a single fluid from 26$0^{\circ}C$ to 12$0^{\circ}C$, and boiling and mixing of a fluid with both decreasing pressure and temperature were studied using the CHILLER program. Calculations show that the precipitation of alteration minerals is due to fluid-andesite interaction as temperature drops. Speciation calculations confirm that the hydrothermal fluids with moderately high salinities and pH 5.7 (acid), were capable of transporting significant quantities of base metals. The abundance of gold in fluid depends critically on the ratio of total base metals and iron to sulfide in the aqueous phase because gold is transported as an Au(HS)$_2$- complex, which is sensitive to sulfide activity. Modeling results for Tongyeong mineralization show strong influence of shallow hydrogenic processes such as boiling and fluid mixing. The variable handing in stageII mineralization is best explained by maltiple boilings of hydrothermal fluid followed by lateral mixing of the fluid with overlying diluted, steam-heated ground water. The degree of similarity of calculated mineral assemblages and observed electrum composition and field relationships shows the utility of the numerical simulation method in identifying chemical processes that accompany boiling and mixing in Te-bearing Au-Ag system. This has been applied in models to narrow the search area for epithermal ores.

• Economic and Environmental Geology
• /
• v.50 no.6
• /
• pp.477-486
• /
• 2017

In this study, we analyze precise seabed geomorphology and conditions for comparing the nearshore areas of the Dongdo(East Island) and the Seodo(West Island) using detailed bathymetry data and seafloor backscattering images, in Dokdo, the East Sea. We have been obtained the detailed bathymetry data and the seafloor backscattering data. The survey range is about $250m{\times}250m$ including land of islets to the nearshore areas of the southern part of the Dongdo and the Seodo. As a result of bathymetry survey, the southern area of the Dongdo(~50 m) is deeper than the Seodo(~30 m) in the water depth. The survey areas are consist of extended bedrocks from land of the Dongdo and the Seodo. The underwater rock region of the Seodo is larger than the Dongdo. In spite of similar extended rocks features from islets, there are some distinctive seabed characteristics between the southern nearshore areas of the Dongdo and the Seodo. The Talus-shaped seafloor environment formed by gravel and underwater rocks originating from the land of the Dongdo is up to about 15 m depth. And the boundary line of between extended bedrocks and seabottom is unclear in the southern nearshore of the Dongdo. On the other hand, the southern coast of the Seodo is characterized by relatively large scale underwater rocks and evenly distributed sediments, which clearly distinguish the boundary of between extended bedrocks and seafloor. This is because the tuff layers exposed to the coastal cliffs of the Dongdo are weak against weathering and erosion. It is considered that there are more influences of the clastic sediments carried from the land of the Dongdo compared with the Seodo. Particularly, the land of the Dongdo has been undergoing construction activities. And also a highly unstable ground such as faults, joints and cracks appears in the Dongdo. In previous study, there are dissimilar features of the massive tuff breccia formations of the Dongdo and the Seodo. These conditions are thought to have influenced the different seabed characteristics in the southern nearshore areas of the Dongdo and the Seodo.

• Korean Journal of Food Science and Technology
• /
• v.47 no.4
• /
• pp.504-510
• /
• 2015

This study was carried out to investigate the antioxidant effects of different parts (stems, leaves, and seeds) of the black raspberry for utilization as food materials. Different parts of the black raspberry were subjected to extraction via ultra-sonication extraction methods using water and ethanol at various concentrations (25, 50, 75, and 100%). Antioxidant capability of the extracts were determined by amounts of phenolic compounds, with flavonoid contents, radical scavenging activity, and reducing power. Irrespectively of ethanol concentration, extracts of stem showed the highest total phenolic compounds and antioxidant activities among different parts of black raspberry. The total phenolic compounds extracted from the black raspberry stem using 25 and 50% ethanol showed $348.21{\pm}5.40$ and $343.39{\pm}5.94mg/g$, respectively. Fifty percent ethanol extracts of the black raspberry stem showed the highest DPPH ($EC_{50}$ value: $60.89{\mu}g/mL$) and ABTS radical scavenging activities ($EC_{50}$ value: $82.57{\mu}g/mL$). Further, 25% ethanol extacts of the black raspberry stem ($0.263{\pm}0.004$) was found to have the highest reducing power. The highest antioxidant activity of black raspberry stem indicates that black raspberry stem may be useful source for functional food.

• Horticultural Science & Technology
• /
• v.29 no.3
• /
• pp.165-171
• /
• 2011

Plant growth retardants reduce the plant height by inhibiting stem elongation in Lilium davuricum. To investigate the plant hormones related to stem elongation, we sprayed 50 $mg{\cdot}L^{-1}$ diniconazole to young plants of L. davuricum and quantified the contents of endogenous gibberellic acids (GA) and abscisic acid (ABA). In GA biosynthesis, L. davuricum had not only the early C-13 hydroxylation ($GA_{19}{\rightarrow}GA_{20}{\rightarrow}GA_1$) pathway resulting in $GA_1$ as the active form but also the non C-13 hydroxylation (NCH, $GA_{12}{\rightarrow}GA_{24}{\rightarrow}GA_9{\rightarrow}GA_4$) with $GA_4$ as the active form. However, the main pathway was NCH because $GA_4$ concentration of 55 $ng{\cdot}g^{-1}$ dry wt was much higher than $GA_1$ content of 0.23 $ng{\cdot}g^{-1}$ dry wt in control plant. Diniconazole inhibited GA biosynthesis through NCH pathway from its early stage. $GA_{12}$ content decreased by diniconazole up to 6% level of that of control and this effect continued to $GA_4$. Diniconazole reduced $GA_{12}$ content by 12.7 $ng{\cdot}g^{-1}$ dry wt, whereas that of control plant was 213.8 $ng{\cdot}g^{-1}$ dry wt. ABA content decreased up to one third of control by diniconazole application. From the contents of endogenous $GA_4$, $GA_1$, and ABA in this study, we could conclude that diniconazole reduces the plant height by inhibiting $GA_4$ biosynthesis in L. davuricum.

• Horticultural Science & Technology
• /
• v.30 no.4
• /
• pp.385-391
• /
• 2012

The growth of terminal shoots of persimmon (Diospyros kaki) was analyzed during the first two months from the time of bud sprout to understand the dynamics of their early growth. Field-grown, mature 'Fuyu' and 'Nishimurawase' trees were used in a three-year study at two locations in Gyeongnam province. The growth of terminal shoots was most active from late April, about 10 days after foliation, to early May, followed by a gradual decline by late May. The increase in leaf area continued unabated throughout May. The weight of a flower bud increased slowly until early May and rapidly after flowering. Although its extension growth had been ceased by late May, dry weight (DW) of a terminal shoot continued to increase almost linearly throughout May due to shoot thickening and continued growth of leaves and fruits. In late May, the leaves and the stem accounted for more than 60% and less than 20% of total DW of a shoot respectively; fruit proportion increased to 7 to 17% by then. Relative growth rate (RGR) of the terminal shoot was higher than 213 $mg{\cdot}g^{-1}{\cdot}d^{-1}$ in late April, but declined to less than 63 $mg{\cdot}g^{-1}{\cdot}d^{-1}$ in late May. Like the pattern of seasonal changes in RGR, net assimilation rate (NAR) of the shoots decreased from 1.9 to 2 $mg{\cdot}cm^{-2}{\cdot}d^{-1}$ to 0.5 to 0.8 $mg{\cdot}cm^{-2}{\cdot}d^{-1}$. An early-season 'Nishimurawase' did not differ from a late-season 'Fuyu' in RGR and NAR during the first two months of growth. The early growth of the shoots was affected mainly by the reserves redistributed from permanent organs, however, environmental conditions at the time was also involved.

• Horticultural Science & Technology
• /
• v.28 no.5
• /
• pp.864-870
• /
• 2010

This study was conducted to determine the effects of foliage plants on reducing indoor carbon dioxide ($CO_2$). Five foliage plants such as $Hedera$ $helix$ L., $Ficus$ $benjamina$ L., $Pachira$ $aquatica$, $Chamaedorea$ $elegans$, and $Ficus$ $elastica$ were selected and cultivated in two different growth medium (peatmoss and hydroball). Each plant was placed in an airtight chamber and then treated with the combinations of two different $CO_2$ concentrations (500 or 1,000 ppm) and two different light intensities (50 or $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). The change of $CO_2$ concentration (ppm) in the airtight chamber during day and night was measured and then converted into the photosynthetic rate (${\mu}mol\;CO_2{\cdot}m^{-2}{\cdot}s^{-1}$). As the results, each foliage plant reduced $CO_2$ level in the airtight chamber for one hour by photosynthesis. $Pachira$ $aquatica$ and $Ficus$ $elastica$ absorbed $CO_2$ more effectively compared to the other plants. The plants exposed to higher $CO_2$ concentration (1,000 ppm) and higher light intensity ($200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) showed more effective $CO_2$ elimination rate and photosynthetic rate. The plants that have wide leaves and big leaf areas such as $Pachira$ $aquatica$, $Hedera$ $helix$ L.,and $Ficus$ $elastica$ showed higher photosynthetic rate than the other plants that have smaller leaves. Released $CO_2$ concentration by respiration of the plants during the night was very low compared to the absorbed $CO_2$ concentration by photosynthesis during the day. There was no significant difference between peatmoss and hydroball medium on reducing $CO_2$ concentration and increasing photosynthetic rate. In conclusion, this study suggested that foliage plants can effectively eliminate indoor $CO_2$. Optimum environmental control in relation to photosyntheis and usage of right indoor foliage plants having lots of leaves and showing active photosynthesis even under low light intensity like indoor light condition would be required to increase the elimination capacity of indoor $CO_2$.

• Horticultural Science & Technology
• /
• v.28 no.5
• /
• pp.743-749
• /
• 2010

Objective of this research was to investigate the effect of various potassium concentrations in fertilizer solution on growth of and nutrient uptake by 'Chugyang' eggplant ($Solanum$ $melongena$ L.). Tissue analyses were conducted to determine the threshold levels of potassium in plants when disorders develop for potassium. The lower leaves of K deficient plants became spotted, yellowing in color, and finally necrosis occurred. The necrosis spread inward and upward. K toxic plants developed necrotic spot at the margin of old leaves and the surface of old leaves were twisted. The tissue K contents in the most recently fully expanded leaves and dry weight of full above ground plant tissue at 35 days after transplanting showed linear and quadratic response to elevated K concentrations with the equation of y=1.127+0.3147x ($R^2$=0.8916) and y=14.92+2.2743x-$0.1402x_2$ ($R^2$=0.8659). When 10% reduction in dry weight set to threshold levels, optimum tissue K contents are in the range from 2.1 to 5.1%. The yield through 150 days after transplanting and tissue K contents at 150 days after transplanting also showed quadratic and linear responses to elevated potassium concentrations in fertigation solution with the equation of y=153.24+345.5x-$18.46x^2$ ($R^2$=0.8620) and y=0.9921+0.3860x ($R^2$=0.9611), respectively. When the 10% reduction in yield is set to threshold levels, the tissue K contents for maximum yield should be around 3.4% to 5.9% in most recently fully expanded leaves.

• Horticultural Science & Technology
• /
• v.28 no.5
• /
• pp.728-734
• /
• 2010

We studied the accumulation and partitioning of dry weight (DW) and nitrogen (N) in different parts of field-grown 'Fuyu' persimmon to elucidate that the foliar applications of supplemental N in June or September compared favorably with the traditional soil application in securing leaf area and fruit production. We also estimated the proportion of N permanently removed from the tree at the end of a growing season. Urea was applied either to leaves in June and/or September or to the soil in June and September for three consecutive years, and the trees were excavated in November for analyses. Total DW ranged from 4.2-4.8, 8.7-9.2, and 17.1-21.5 kg in a 4-, 5-, and 6-year-old tree, respectively, without statistical difference among the four treatments. Of the total DW, 3.3-10.2% was in shoots, 5.7-10.5% in leaves, 8.3-31.4% in aerial woods, 13.0-27.0% in root, and 28.0-59.3% in fruits. As the trees became more productive, DW proportion of fruits significantly affected that of the root: in 6-year-old trees, root DW accounted for only 10.6-15.8% of the tree total when fruit DW accounted for 50-60%. N contents ranged from 24.6-28.3, 48.3-53.5, and 98.3-122.6 g in a 4-, 5-, and 6-year-old trees, respectively, without statistical difference among the treatments. Of the total N, 6.2-11.5% was in shoots, 16.7-24.3% in leaves, 17.6-23.5% in aerial woods, 17.2-37.5% in roots, and 16.9-34.4% in fruits. As in DW, the increase in the proportion of N in fruits decreased in the root most significantly. Application methods for supplemental N did not affect the proportion of DW and N removed from the tree through abscising leaves and harvested fruits. Percentage of DW removal was 41 in 4- and 5-year-old trees, but it was 61 in more productive 6-year-old trees; that of N was 39, 43, and 49%, respectively. No significant changes in the contents of DW and N in field-grown trees, as well as their percentages removed from the tree at the end of the season, demonstrated that foliar application of supplemental N was as good as soil applications with much less N.

• Horticultural Science & Technology
• /
• v.28 no.5
• /
• pp.850-856
• /
• 2010

An in vivo oral glucose tolerance test (OGTT) was performed on hyperglycemic male Sprague-Dawley rats to assess the effect of fruits and vegetables ($1g{\cdot}kg^{-1}$ body weight) on blood glucose levels (${\Delta}BGLs$) at different time intervals of 0, 5, 15, 30, 60, 90 and 120 min. The areas under glucose curve (${\Delta}AUCs$) were calculated at 120 min of OGTT by trapezoid method. Total phenolic content (TPC) and anti-oxidant activity (AOA) of fruits and vegetables were assayed in vitro by Folin Ciocalteu and DPPH (2, 2-diphenyl-1-picrylhydrazyl) methods, respectively. At the end of the experiment the correlations among the parameters TPC, AOA and ${\Delta}AUC$ was estimated by Pearson's correlations. Among fruit crops, tangerine, plum, grape and pear and among vegetables, blue leaf mustard, cabbage, chicory, broccoli and others exhibited significant hypoglycemic effects by reducing ${\Delta}BGLs$ with significant ${\Delta}AUC$. The effective ${\Delta}AUC$ ranged from $5548.2{\pm}462.1$ to $3823.3{\pm}282.0mg-min{\cdot}dL^{-1}$. The TPC and AOA ranged from $0.063{\pm}0.00$ to $0.913{\pm}0.14mg{\cdot}g^{-1}$ GAE and $01.05{\pm}0.08$ to $75.46{\pm}0.06%$, respectively. Overall, six fruits and fifteen vegetables exhibited higher TPC and one fruit and four vegetables exhibited higher AOA. There was a better correlation among TPC, AOA and ${\Delta}AUC$ of fruits and TPC & AOA of vegetables. We report that hypoglycemically significant fruits and vegetables investigated in this study have pharmacological importance which reduced ${\Delta}BGLs$ through insulin like activity and AOA in prevention of type-2 diabetes.