• Journal of Wetlands Research
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• v.15 no.4
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• pp.535-541
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• 2013

The urbanization affects significantly on a natural water circulation system by increasing the imperviousness rate. It is also negatively affecting on urban temperature, environmental pollution, water quality, and aqua-ecosystems. The Korea MOE (Ministry of Environment) adapted a new environmental policy in order to reduce the impact of urbanization, which is the Green Stormwater Infrastructure (GSI) program. The GSI can be achieved by protecting conservable green spaces, enlarging more green spaces, and constructing more permeable pavements. The GSI is including many different techniques such as bioretention, rain garden, infiltration trench and so on. Also It is the infrastructures using natural mechanisms of soils, microorganisms, plants and animals on a water circulation system and pollutant reduction. In this research, a multi functional GSI technology with infiltration-filtration mechanisms has been developed and performed lab-scale tests to evaluate the performances about infiltration rate restoration and pollutant reduction. The most of pollutants including metals, organics and particulates were reduced about 50~90% due to water infiltration and storage functions. The clogging was found when the TSS loading rate was reached on $8.3{\sim}9.0kg/m^2$, which value is higher than the values in literatures. It means the new technology can show high performances with low maintenances.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.79-92
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• 2011

In this study, wave pressure of short-period gravity waves and tsunami acting on the upright section of the horizontal-slit type caisson placed on the impermeable or permeable seabed, which is a well-known permeable breakwater with a good wave controlling ability, are investigated via numerical simulations. Further, the permeable seabed was modeled as the porous media with porosity of 0.4. Using the numerical results, the effects of the seabed conditions on the wave pressure on the front wall and inside wall of the chamber have been studied. In the numerical simulations, short-period gravity waves and tsunami(solitary wave or bore) with the same amplitude to the gravity wave are considered. A numerical wave tank is used, which is able to consider a gas-liquid two-phase flow in the same calculation zone. Numerical results show that the wave pressure of the tsunami was 3~5 times higher than the short-period gravity waves acting on the front wall and it was 2~4 times higher than the short-period gravity waves acting on the inner wall.

• The Journal of the Petrological Society of Korea
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• v.13 no.3
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• pp.161-177
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• 2004

The Cretaceous pink granites of the finan area, southwestern Ogcheon belt, are adjacently developed in the eastern part (Keg) and western part (Kwg) as stocks, respectively. Keg of rounded shape occur as mainly medium-coarse grained rocks, whereas Kwg of ellipsoidal shape occurs as medium-coarse grained ones with partly porphyritic and fine-grained textures. Miarolitic cavities of them are often seen and can be observed more frequently in Kwg than Keg. Rose and counter fracture diagrams of the two granites show that Keg and Kwg have more potentiality of non-dimension and dimension to non-dimension stones, respectively. Physical properties such as porosity and absorption ratio have 0.25% and 0.65％, and 0.43% and 1.11%, respectively, which could suggest that emissions of gas phase at later magma stages are abundant in Kwg than those of Keg. From the major and trace elements petrochemisoy, they belong to acidic, peraluminous and calc-alkaline rocks, showing that Kwg are later product than Keg of the same granitic parent magma. REE concentrations normalized to chondrite value have trends of gradual and parallel enriched LREE and depleted HREE. Eu negative anomalies of Kwg are far more severe than those of Keg, which suggest that plagioclase fractionation in Kwg was much stronger than that of Keg. In the magnetic susceptibility vs. petrochemical and modal parameters, they all belong to magnetite-series and I-types, and can be classified as weakly-moderately ferromagnetic rocks. And the above relations could suggest that their susceptibility values are more mainly depended on ferromagnetic opaques than ferromagnetic and paramagnetic assemblages (Bt ＋ Ch ＋ Ser ＋ Op).

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.128-137
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• 1999

In this study, shiitake mushrooms were dried by hot air, vacuum and freeze drying methods and theire physical properties were compared. Since the pore size affects the amount of absorption, the characteristics of water sorption were investigated at various humidities and temperatures. Results showed that the freeze dried product had the greatest pore area and the highest absorption capacity. However, all the dried samples showed similar quality. The browning degrees were severely changed with increased relative humidities and temperatures. Among these drying methods, the freeze drying gave the greatest change in browning degree. The GAB monolayer moisture contents of the dried shiitake mushroom were $5.3{\sim}7.7%$. The prediction model was also provided using parameters such as relative humidity, temperature and pore area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.794-801
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• 2017

When a radial wheel is placed so as to partially overlap a conductive plate and rotated, a lift force is generated on the wheel, a thrust force along the edge, and a lateral force which tends to reduce the overlap region. When several of these wheels are combined, it is possible to realize a system in which the stability of the remaining axes is ensured, except in the traveling direction. To validate the overall characteristics of the multi-wheel system, we propose a transfer system levitated magnetically using radial electrodynamic wheels. The proposed system is floated and propelled by four wheels and arranged in a structure that allows the thrusts generated by the front and rear wheels to offset each other. The dynamic stability of the wheel and the effect of the pole number on the three-axial forces are analyzed by the finite element method. At this time, the thrust and levitation force are strongly coupled, and the only factor affecting them is the wheel rotation speed. Therefore, in order to control these two forces independently, we make use of the fact that the ratio of the thrust to the levitation force is proportional to the velocity and is independent of the size of the gap. The in-plane and out-of-plane motion control of the system is achieved by this control method and compared with the simulation results. The experimental results show that the coupled degrees of freedom can be effectively controlled by the wheel speed alone.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.581-589
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• 2005

Recently, membrane processes have been replacing the conventional processes for waste water treatment to produce better quality of effluent and to meet more stringent regulations because of water shortage. However, using membrane processes for water treatment has confronted with fouling and difficulty in treating dissolved organic pollutants. In this study, membrane process equipped with crossflow microfiltration is combined with coagulation process using alum and PAC to improve permeability and treatment efficiency. The effects of coagulant dosage and optimum membrane operating conditions were investigated from measurement of permeate flow, cumulative volume, total resistance, particle size, dissolved organic pollutant, dissolved aluminium and quality of effluent. Characteristic of PAC coagulation was compared with that of alum coagulation. PAC coagulation reduced membrane fouling because of forming larger particle size and increased permeate velocity and cumulative volume. Less dissolved organic pollutants and dissolved aluminum made decreasing-rate of permeate velocity being lowered. At using $0.2\;{\mu}m$ membrane, cake filtration observed. At using $0.45\;{\mu}m$ membrane, there was floc breakage due to shear stress occurred born circulating operation. It made floc size smaller than membrane pore size, which subsequently to decrease permeate velocity and to increase total resistance. The optimum coagulation dosage was $300{\pm}50\;mg/L$ for both alum and PAC. PAC coagulation was more efficiently used with $0.2\;{\mu}m$ membrane, and the highest permeate flux was in using $0.45\;{\mu}m$membrane. The greatest efficiency of treatment was as follows; turbidity 99.8%, SS 99.9%, $BOD_5$ 94.4%, $COD_{Cr}$ 95.4%, T-N 54.3%, T-P 99.8%.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.2
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• pp.101-107
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• 2001

The experiment was conducted to investigate the agricultural utility of macro-porous calcium-silicate rnineral(CellCaSi) as topsoil mixture, as well as to estimate as a soil conditioner. The bulk density of CellCaSi which is consisted of various particle sizes ranging from 1mm to 3.35mm was about $0.42g/cm^3$, and its maximum porosity was approximately 81.4%. We also investigate gerrnination rates for Cabbage and Lettuce to obtain the suitable mixing ratios of CellCaSi with topsoil. Among 4 different mixing ratios, the germination rates of ropsoil mixed with 10% of CellCaSi were 94.1% and 64.6% for Cabbage and Lettuce, respectively resulted in the mosr suitable for germination. The growth rates for Cabbage and Lettuce showed thar 10% and 20% of CellCaSi treatments signification influenced the fresh weight. To observe the adsorption capacity of CellCaSi, CellCaSi was treated with a chemical fertlizer(N:P:K=18:18:18). lncreasing the contents of N, P and K, the amounts of adsorption by CellCaSi for these element also increased. The most suitable types nutrient resources for growth condition of Cabbage, and Lettuce were Fer-1 and Fer-0.5.

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.511-523
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• 1995

The elastic open activator is one of the modified myodynamic activator. The reduced size of the appliance mass motivates the patients' comfort and longer time of wearing. Its peculiarities in loose fitting and the lack of appliance stabilization in the mouth draws the tongue and the surrounding functional matrices on close interaction with the appliance, consigns the physiologic exertion to target structures, and eventually makes it feasible to the inland of non-extraction treatment In the context of the sagittal malocclusion, the orthodontic trench is dependent upon the growth of basal structure aimed, therefore, it is contemplated to grabble the effects of Elastic Open Activator upon the class II malocclusion of growing child retrospectively. The cephalometric headfilms and study models of nine Class II malocclusion of growing child retrospectively. The cephalometric headfilms and study models of nine class II division 1 and five division 2 patients were evaluated and analyzed, and the following observations were drawn, 1. The maxilla maintained a normal growth pattern in both groups. 2. The mandible grew anteroinferiorly in both groups. 3. The upper incisors tipped ligually in Class II division 1 and tipped labially in Class II division 2 and anterior vertical alveolar growth was interrupted in both groups. 4. The lower incisors tipped labially. 5. There was an arch expansion in both groups and increase of available space in Class II division 2

• Journal of Conservation Science
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• v.27 no.4
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• pp.395-401
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• 2011

After pressurized impregnation treatment, which has been proposed as an effective conservation method for stone cultural property, was executed with methyl metacrylate (MMA), MMA-butyl acrylate (PMB73) mixture and MMA-vinyl trimethoxy silane (PMV5) co-monomer mixture, the physical-chemical properties on the sand stone and the granite impregnated were evaluated. Compared to the case of granite, the impregnation ratios of sand stone showed larger values in the range of 3.2 to 3.7 wt% and these were increased up to 32% when the decompression process was applied to autoclave. The physical properties of sand stone such as anti-moisture property, flexural strength, impact property and ultrasonic velocity were also higher values than those of granite, which can be interpreted by high impregnation ratio resulted in many void within sand stone. The impact failure energy was 1.22 J for PMMA, 1.84 J for PMB73, and 2.8 J for PMV5, respectively. Since the inorganic affinity of treatment agent is more effective than the molecular structure of acrylic agent, PMV5 improved inorganic property indicates the optimum impact property.

• The Journal of Engineering Geology
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• v.10 no.2
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• pp.18-35
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• 2000

The most dominant type of landslide in Korea is debris flows which mostly take place along mountain slopes during the rainy season, July to August. The landslides have been reported to begin activation when rainfall is more than 200mm within 2days. The debris flows are usually followed by translational slips which occur upper part of mountain slopes and they transit to debris flow as getting down to the valleys. Lithology, location, slope inclination, grain size distribution of soil, permeability, dry density and porosity have been proved as triggering factor causing translational slides. The triggering data taken from mapping are statistically analysed to get landslide potential quantitatively. Rock mass creeps mostly occur on well bedded sedimentary rocks in Kyeongsang Basin. Although the displacement of rock mass creep is relatively small about 1m, the creep can cause severe hazards due to relatively large volume of the involved rock mass. Examples are rock mass creep occurred in the mouth of Hwangryongsan Tunnel, in Chilgok and in Sachon in 1999. Although the direct factor of the creeps are due to slope cutting at the foot area, more attention is required A rotational slide occurring within thick soil formation or weathered rock is also closely related to bottom part of slope cutting. It is propagated circular or semi-circular type. Especially in korea, the rotational slide may be frequently occurred in Tertiary tuff area. Because they are mainly composed of volcanic ash and pyroclastic materials, well developed joints and high degree of swelling and absorption can easily cause the slide. The landslide among the Pohang-Guryongpo national road is belong to this type of slide.