• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.703-709
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• 2012

We studied the community fluctuations of benthic macroinvertebrates of forest fired area in Samcheok-si from 2001 to 2009. Total collected macroinvertebrates species were 18 belonging to 14 families, 8 orders, 3 classes, and 2 phyla in 2001, and 70 belonging to 40 families, 15 orders, 7 classes and 5 phyla in 2009 (9 years after the forest fire). During the first four years after the forest fire, dipteran insects were dominant, but after then, ephemeropteran insects have increased in abundance and richness. As time elapsed from the fire, dominance indices were decreasing, while species diversity, richness and species evenness indices were increasing.

• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.419-428
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• 2018

This study is aimed at estimating and mitigating the impact of urban development on watershed hydrology for new town experienced with dramatical change of land use from rural to urban. The climate change scenario, representative concentration pathway (RCP), revealed direct response of runoff depth to precipitation, which increased until year 2100. The types of areas for urban use in addition to climate change affected the efficiencies of bioretention, applied as a low impact development (LID). Combining different areas for urban use suggested that a possible approach to mitigate the urban development impact on watershed hydrology by supplementing captured rainfall potential from area to area and attenuating peak discharge and retarding its time of concentration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4B
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• pp.379-388
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• 2010

This study examined the physical effects on the river changes downstream of Andong dam and simulated the reproduction of sand bars and the geomorphic changes numerically. The river bed downstream of Aandong dam and Imha dam was decreased and the mean diameter of bed materials was increased, and the number of lower channels was increased. The vegetated area was slightly increased after Andong dam construction. Moreover, the area was abruptly increased after Imha dam construction. The bankfull discharges was estimated to 580 $m^3/s$ after the dams construction and 2,857 $m^3/s$ before the dams. A flood mitigation safety by the dams construction considering return period was increased to 5 to 10 times. As a result of meso-scale regime analysis by using banfull discharge, the regime between single bars and multiple row bars before the dams construction was changed to completely the regime of multiple row bars after the dams. The numerical simulation results showed that the sand bars and lower channels were developed before the dams, and braided river was developed after the dams. This meant that the patterns of sand bars was changed by variable discharge due to the dams construction.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.3
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• pp.153-157
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• 2010

We studied the adsorption efficiency of steelmaking slag in removing volatile organic compounds (VOCs) for increasing the recycling rate of steel-making slag. Ceramic filter was prepared by mixing the steel-making slag and the diatomite which is used as adsorbents due to the advantage of the high specific surface area and regular mesopores. The adsorption efficiency for VOCs removal was about 80%, 96% and 85% in acetaldehyde, formaldehyde and ammonia, respectively. The adsorption efficiency over 80% for all The gases showed the practical possibility as the adsorption filter.

• The Korean Journal of Ecology
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• v.16 no.1
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• pp.39-50
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• 1993

The geographical variation of the germination response and the seedling growth of the seed populations of hemistepta lyrata bunge distributed in the southern area of korean peninsula (seoul, yongwol, andong, $Ch^{\prime}angwon, \;Sunch^{\prime}on$)was investigated. Five populations were divided into two principal groups according to the phases of their seed germination. The first group consisting of the seoul and yongwol population was 62% and 64%, respectively, in the final germination percentage of 32%, 24% and 28%, respectively, were Andong, $Ch^{\prime}angwon\;and\;Sunch^{\prime}on$ populations. The seed populations of hemistepta lyrata bunge which hardly germination. the germination of seoul and yongwol populations located at the higher latitudes took plase synchronously in early autumn. On the other hand, andong, $Ch^{\prime}angwon\;and\;Sunch^{\prime}on$ populations located at the lower latitudes showed a tendency to germinata asynchronously in late autumn. the speed of the seedling growth of the populations located at the higher latitudes was greater than that of the populations at the lower latitudes. Therefore the geographical variation in the germination response and the seedling growth of the seed populations of hemistepta lyrate bunge appeared to be an important ecological strategy to maintain their existence in the extreme environmental variations.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.465-472
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• 2014

The tobacco whitefly, Bemisia tabaci, infest the Oriental melon and give significant economic damage along with its virus-vectoring activity. Various biotypes of B. tabaci have been well known and are classified depending on the severity of crop damage and insecticide susceptibility. In this study, B. tabaci adults were collected in the melon fields located in Poongchun-myeon, Andong, Korea and diagnosed on their biotypes using PCR molecular markers. From the all the 11 greenhouses, B. tabaci biotype Q was identified. In addition, biotype B adults were also found from the 4 greenhouses. These results report the first occurrence of B. tabaci at the Oriental melon farms in Gyeongbuk province with mixed infection by the two biotypes in the area.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.520-524
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• 2000

A ejector system is one of the fluid machinery, which has been mainly used as an exhaust pump or a vacuum pump. The ejector system has often been pointed out to have only a limited efficiency because it is driven by pure shear action and the mixing action between primary and secondary streams. In the present work, numerical simulations were conducted to investigate the effects of the geometry and the mass flow ratio of supersonic ejector-diffuser systems on their mixing performance. A fully implicit finite volume scheme was applied to solve the axisymmetric Navier-Stokes equations, and the standard ${\kappa}-{\varepsilon}$ turbulence model was used to close the governing equations. The flow fields of the supersonic ejector-diffuser systems were investigated by changing the ejector throat area ratio and the mass flow ratio. The existence of the second throat strongly affected the shock wave structure inside the mixing tube as well as the spreading of the under-expanded jet discharging from the primary nozzle, and served to enhance the mixing performance.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.459-464
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• 2000

In order to investigate the effectiveness of an orifice system in producing pressure drops and the effect of compressibility on the Pressure drop, computations using the mass-averaged implicit Wavier-Stokes equations were applied to the axisymmetric pipe flows with the operating pressure ratio from 1.5 to 20.0. The standard k-e turbulence model was employed to close the governing equations. Numerical calculations were carried out for some combinations of the multiple orifice configurations. The present CFD data showed that the orifice systems, which have been applied to incompressible flow regime to date, can not be used for the hint operating Pressure ratio flows. The orifice interval did not strongly affect the total pressure drop but the orifice area ratio more than 2.5 led to high pressure drops. The total pressure drop rapidly increased in the range of the operating pressure ratio from 1.5 to 4.0, but it did not depend on the operating pressure ratio over 4.0.

• The Journal of the Petrological Society of Korea
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• v.25 no.1
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• pp.89-93
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• 2016

Yeongju and Andong granites, located in the northeastern Yeongnam massif, reveal very similar emplacement ages but distinct initial isotopic compositions of strontium. However, previous studies used different boundaries to distinguish these batholiths. In this study, we determined Sr isotopic compositions of apatite separated from the granites of the area to find out the proper boundary and propose the location of such boundary based upon analysis.

• Journal of Powder Materials
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• v.25 no.4
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• pp.309-315
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• 2018

In the present work, we synthesize nano-sized ZnO, $SnO_2$, and $TiO_2$ powders by hydrothermal reaction using metal chlorides. We also examine the energy-storage characteristics of the resulting materials to evaluate the potential application of these powders to dye-sensitized solar cells. The control of processing parameters such as pressure, temperature, and the concentration of aqueous solution results in the formation of a variety of powder morphologies with different sizes. Nano-rod, nano-flower, and spherical powders are easily formed with the present method. Heat treatment after the hydrothermal reaction usually increases the size of the powder. At temperatures above $1000^{\circ}C$, a complete collapse of the shape occurs. With regard to the capacity of DSSC materials, the hydrothermally synthesized $TiO_2$ results in the highest current density of $9.1mA/cm^2$ among the examined oxides. This is attributed to the fine particle size and morphology with large specific surface area.