• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.1-7
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• 1983

In spite of extensive knowledge of the surface chemistry and the transport mechanism in filtration systems, there is still insufficient understanding of the physical characteristics of suspensions and the system components. Because of this, no filtration mechanisms are mathematically generalized to the full extent. The purpose of this paper is to propose experimental equations for the filtration process. using the tracer study in filter layer. Some of results are as follows. (1) The Volume of the specific deposit (${\sigma}$) in filtration was directly measurable using the tracer study without interrupting the filtration. (2) It was also confirmed that the head loss in filtration was greatly in fluenced by the micro-air babbles. (3) The correction coefficient(f) was introduced into the Kozeny-Carman equation in order to apply it for the clogging filter media. The coefficient(f) was experimentally obtained. The total head loss of the filter media is given by next equation. $${\frac{h}{h_0}}={\frac{1}{L}}{\int}^{z=L}_{z=0}f({\sigma})g({\varepsilon}_0,{\sigma})dz$$ $$f=aexp(-b{\sigma})$$ The above equation was applicable without regard to the variation of the suspension concentration, the filter medium diameter, the filter depth, the filtration velocity, and the amount of aluminum in all continuous filtration experiments. (4) The total head loss was graphically generalized assuming mathematical filtration models I II (see fig. 7,8) (5) The total head loss was obtained from the filtration model in the field filtration conditions. (see fig. 9,10)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.5
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• pp.375-380
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• 2017

This paper reports the results of an acceleration test to predict the contact-induced failure that could occur at the cylinder-to-hole joint for the fuel rod of a sodium-cooled fast reactor (SFR). To incorporate the fuel life of the SFR currently under development at KAERI (around 35,000 h), the acceleration test method of reliability engineering was adopted in this work. A finite element method was used to evaluate the flow-induced vibration frequency and amplitude for the test parameter values. Five specimens were tested. The failure criterion during the life of the SFR fuel was applied. The S-N curve of the HT-9, the material of concern, was used to obtain the acceleration factor. As a result, a test time of 16.5 h was obtained for each specimen. It was concluded that the $B_{0.004}$ life would be guaranteed for the SFR fuel rods with 99％ confidence if no failure was observed at any of the contact surfaces of the five specimens.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.118-122
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• 2016

When a geometric size of moonpool and an inflow velocity are determined based on the similarity of Froude number, Reynolds number is depending on the scale ratio of moonpool geometry. It means that different characteristics of flow fluctuations in moonpool can be observed depending on the scale ratio of moonpool even though Froude number is the same. In the present study two dimensional numerical simulations were performed to investigate the influence of scale ratios on the flow characteristics inside the moonpool. The inflow velocity at several scale ratios was determined to keep Froude number constant. A periodic response was observed in a small size of moonpool while a large moonpool showed complicated fluctuations with various amplitudes and frequencies, which made it difficult to distinguish the statistical steady-state response from the temporal responses in the case of large moonpool. The similarity of Froude number gave rise to a spectral characteristic which was inversely proportional to the square root of scale ratios ($f_{0.5}{\approx}{\sqrt{2}}f_1{\approx}2f_{2.0}$) but a low frequent occurrence of strong vortex ($f_{2.0}=0.07$)which is observed inside the large moonpool was characterized depending on scale ratios.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.213-219
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• 2006

The Yongjang mine is located in Masan City, Gyeongsangnamdo, which consists of a black shale possessing quartzite veins with othercompositions such as gold, silver, and sublimated sulfur. The average width of the veins is $9{\sim}17cm$ and the average degrees of the gold and silver are 3.6 g/t and 113.6 g/t respectively. A regional and a detailed scale electrical resistivity surveys are conducted to determine the existence of the mineralization zones and the linear structures in the study area. In addition, surveys of a several different array methods are conducted such as dipole-dipole array in the surface and borehole-to-surface array, surface-to-borehole array, and dipole-dipole array in the borehole. The method of element division can be applied to the region in which the borehole is curved, inclined or the distance between the electrodes is shorter than that of nodal points, because the coordinate of each electrode cannot be assigned directly to the nodal point if several electrodes are in an element. Yongjang vein is extended longer under the subsurface than on the surface in the images reconstructed from the 3D inversion. Therefore, it is recognized that the 3-D interpretation of the electrical resistivity survey is a very useful method to figure out the existence of strike and extension direction because the mineralization zones and the linear structures are shown in each depth.

• The Journal of the Petrological Society of Korea
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• v.15 no.1 s.43
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• pp.10-24
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• 2006

Staurolite grains in staurolite, kyanite and sillimanite zones occurred in the Littleton Formation, Northcentral Massachusetts have interpreted to form by Barrovian-type metamorphism during Acadian orogeny. However, various occurrence of staurolite in the three zones, (a) porphyroblast, (b) randomly oriented and coarse-grained muscovite pseudomorph after staurolite, (c) recrystallized staurolite at the margin of garnet porphyroblast and within the pseudomorph, indicates that they have resulted from polymetamorphism. Staurolite in these three metamorphic zones can be formed by demise of chlorite or chloritoid that depends on difference of bulk-rock compositions and changes of P-T conditions. Staurolite modal proportion calculated in MnNCKFHASH system using THERMOCALC program reveals that staurolite could have grown with garnet with increasing pressure and temperature, if it coexist with chlorite. After demise of chlorite and appearance of biotite, staurolite mode decrease with increasing pressure and temperature. Therefore, based on the previous P-T paths for the Acadian metamorhism, staurolite porphyroblast grew with garnet during 400-370 Ma. Randomly oriented and coarse-grained muscovite pseudomorphs after staurolite probably have grown due to heating with appearance of kyanite and sillimanite. Consequently, pseudomorphisrn of staurolite occurred by heating derived from locally intense Alleghanian shearing (ca. 320-300 Ma) overprinted the Acadian metamorphism. Recrystallized fine-grained staurolite in sillimanite zone observed between the grain boundaries of muscovite in the pseudomorphs and at the edge of garnet porphyrobasts has formed during decreasing temperature and pressure (ca. 300-280 Ma) after peak temperature (ca. $700^{\circ}C$) of the Allegllanian metamorphism.

• Economic and Environmental Geology
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• v.39 no.1 s.176
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• pp.39-51
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• 2006

Rare earth elements(REEs) in transgressive shelf core sediments were analysed to identify constraints of REE distribution patterns and sediment provenances in the northern East China Sea(ECS). Sediments of Chinese and Korean rivers, such as Huanghe and Yangtz rivers, Keum and Yeongsan rivers that supply sediments to the northern ECS, were also analysed to figure out their typical REE distribution patterns. The distribution patterns of Chinese and Korean river sediments, which are normalized with upper continental crust (UCC) REE values, appear to be enriched in middle rare earth elements (MREEs) in Chinese river sediments, whereas in light rare earth elements (LREEs) in Korean river sediments. We assign the MREE-enriched convex-type distribution pattern in Chinese river sediments as 'C-type', and the LREE-enriched linearly decreasing pattern in Korean river sediments as 'D-type'. A major constraint of the REE concentration in northern ECS core sediments is interpreted to be LREE-enriched monazite $((Ce,\;La)PO_4)$ that is ubiquitous in and around the study area. Meanwhile, the distribution pattern of northern ECS sediments appears to be between the C-type and the D-type. We suggest that the nothern ECS sediments are the mixture of China and Korea riverine sediments that have been accumulated in paleo-river mouth, paleo-coast, and present-day shelf environment as well.

• Economic and Environmental Geology
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• v.34 no.1
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• pp.147-156
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• 2001

Titanomagnetites, the primary magnetic mineral in submarine basalts, generally has undergone some degree of low temperature oxidation to cation-deficient titanomaghemites. Synthetic analogues of natural titanomaghemite have been prepared by the removal of iron mechanism employing a low-temperature aqueous oxidation method. Along with the low-temperature oxidation of titanomagnetite, magnetic properties of titanomagnetite change sensitively. The results show that as the degree of oxidation increases, the Curie temperature (Tc) increases from $166^{\circ}C$ to $400^{\circ}C$, saturation magnetization (Ms) at room temperature decreases from 126.30 kAlm (25.26 emu/g) to 16.55 kAlrn (3.31 emu/g) monotonously, and coercive force (Hc) and coercivity of remanence (Hcr) increase from 6.13 kAlm (77 Oe) and 23.24 kAlm (292 Oe) to 38.83 kNm (488 Oe) and 47.03 kAlm (591 Oe), respectively. Low field susceptibility (X) decreases from $2023{\times}10^{-6}SI$ to $84{\times}10^{-6}S1$. Based on the results of this study, it is interpreted that the NRM intensity variations of the oceanic crust of presetnt day to 30 Ma is due to the formation of titanomahemites of various degree of oxidation by the low-temperature aqueous oxidation of titanomagnetite, while the magnetic intensity changes of the oceanic crust older than 30 Ma is presumably caused by the combined effect of the formation of titanomaghemites and subsequent inversion of titanomagnemites. DetaileJ causes of the variations of NRM intensity of the oceanic crust may be revealed by systematic studies of the oceanic-floor basalts in the future.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.358-365
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• 2000

To evaluate the influences of stocking and removal of silver carp on plankton communities and physicochemical parameters, fish biomanipulation was conducted in six enclosures constructed on the coast of a hypertrophic lake during the summer of 1997. Of these, three enclosures were established for the fish-stocking experiment; one fishless enclosure used as a control and two enclosures with high and low densities of fish. The other three enclosures for the fish-removal experiment were prepared in an entirely converse process compared to that for fish stocking. The results of randomized intervention analysis (${\alpha}=0.05$) showed significant changes in several physicochemical parameters and plankton communities after fish stocking and removal. Fish stocking decreased water transparency, DO, pH and chi-a (> $40\;{\mu}m$), while increasing the concentration of nitrogen and chi-a (<$2\;{\mu}m$). However, water transparency did not increase by fish removal. Small plankton communities, such as picocyanobacteria, eukaryotic picoplankton and ciliates (<$2\;{\mu}m$) showed significant reciprocal changes after both fish treatments: increase by the presence of fish and decrease by the absence of fish. No count of large sized phytoplankton and zooplankton showed significant change in the presence of fish, while large zooplankton, Diaphanosoma, Cyclopida and nauplii were significantly increased by fish removal. Although the frequent heavy-winds and endless supply of phosphorus from the lake sediment strongly disturbed the fish behavior and enclosure management, the stocking and removal of silver carp showed an obvious reciprocal influences on plankton communities and its physico-chemical parameters in a shallow-hypertrophic lake.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.289-297
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• 2007

Slope failure that is occurred by rainfall generates a lot of property damages and loss of lives. Slope stability management and reinforcement countermeasure can be attained through continuous monitoring about various slope types that adjoin in human's life for reducing slope failure from natural and artificial cut slope hazards. The study area is rock slope that is consisted of gneiss, and large scale joint set is ranging by fault activity. This rock mass is exposed during long period and has lithological weathering property of weathered rock or soft rock. In-situ investigation carried out after divide by natural slope and cut slope. As a result, the natural slope appeared to high possibility of planar failure and wedge failure in few joint points that main joint set is formed. On the other hand, slope failure conformation in cut slope was superior only wedge failure occurrence possibility in eight joint points. In result of numerical analysis using SLIDE 2D, the minimum safety factor was analyzed slope stability for cut slope relatively low than natural slope in this study.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.4
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• pp.169-179
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• 2011

To investigate the controlling factor and accumulation of trace metal concentrations in Chun-su Bay sediments, grain-size, specific surface area, organic carbon content, calcium carbonate content, and concentration of Al, Fe, Na, K, Mg, Ca, Ti, Mn, P, S, Ba, Sr, Li, Co, Cr, Ni, Cu, Zn, As, Cd, Cs, Sc, V, Sn were analyzed. Controlling factors of metals were quartz-dilution, calcium carbonate and coarse sand or K-feldspar. Although the distribution of V, Co, Cr, Ni, Cu, Zn, Sn, and Cd concentration was explained by grain-size effiect, Mn and As showed the similar importance of grain-size effect and coarse sand or K-feldspar factors. By virtue of enrichment factor and 1 M HCl experiment, there were little enrichment in all the trace metals in bay sediments, which were explained well by geochemical properties of sediments. Since the concentration levels of As in coarse sand were high as much as those in fine-grained sediments and it was combined with Mn oxide (1 M HCl leached) and K-feldspar (residual), it was suggested that when the enrichment of As in sediments would be assessed, it is necessary to separate the coarse sand from bulk sediments or to use only sediments with higher than 10% in < $16{\mu}m$ fraction.