• Journal of the Korean Society of Groundwater Environment
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• v.7 no.2
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• pp.89-96
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• 2000

Slug tests are the most widely used field method for quantification of hydraulic conductivity of porous media. Well recovery is affected by well casing, borehole radii, screened length, hydraulic conductivity, and specific storage of porous media. In this study, a new slug tests model was developed through finite element approximation and the validity and usefulness of the model were tested in various ways. Water level fluctuation in a well under slug test and cons-equent groundwater flow in the surrounding porous medium were appropriately coupled through estimation of well-flux using an iteration technique. Numerical accuracy of the model was verified using the Cooper et al. (1967) solution. The model has advantages in simulations for monitored slug tests, partial penetration, and inclusion of storage factor. Volume coverage of slug tests is significantly affected by storage factor. Magnitude and speed of propagation of head changes from a well increases as storage factor becomes low. It will be beneficial to use type curves of monitored head transients in the surrounding porous formation for estimation of specific storage. As the vertical component of groundwater flow is enhanced, the influence of storage factor on well recovery decreases. For a radial-vertical flow around a partially penetrated well, deviations between hydraulic estimates by various methods and data selection of recovery curve are negligible on practical purposes, whereas the deviations are somewhat significant for a radial flow.

• Journal of Korean Society of Steel Construction
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• v.29 no.2
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• pp.147-158
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• 2017

The present study focused on the structural performance of newly developed prefabricated composite columns (PSRC composite column) using bolt-connected steel angles. Concentric axial loading tests were performed for four 2/3 scaled PSRC column specimens and two conventional SRC column specimens. The test parameters were the spacing and sectional configurations of lateral reinforcement, and width-to-thickness ratio of steel angles. The test results showed that the axial load-carrying capacity and deformation capacity of the PSRC column specimens were comparable to those of the conventional SRC column specimens. Closely spaced steel plates and Z-shaped steel plates for lateral reinforcement increased the deformation capacity of the PSRC column specimens. The load-carrying capacity was greater than the prediction by current design codes. Numerical analysis was performed for the specimens. The results agreed well with the test results in terms of initial stiffness, load-carrying capacity, except for strength degradation due to cover concrete spalling.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.5
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• pp.452-460
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• 2008

Anti-foaming agents and foam fences have been used to remove the foam at the outfall of power plants, but there are some problems as consumption of maintenance costs and insufficiency of effect. Therefore, development of the methods how to remove the foam by stable coastal structure has been required. In this study, numerical simulation of air entrainment was carried out to design the submerged outlet structure for reducing foam using curtain walls. The air entrainment rate and the discharge of entrained air change according to the shape of weir and curtain wall. Hence, it is necessary to design the optimum section through comparison of each case. The optimum section which has the maximum rate of foam reduction was determined by the simulation results. In addition, it was found that the flow velocity at the submerged outlet is to be smaller than 1 m/s and the submerged depth of curtain wall is to be taller than height of the submerged outlet section.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.638-644
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• 2020

This study examines cracks that occur under the load of an aircraft. The life of aircraft vulnerability structures was analyzed and structural fitting improvements were made. Structural integrity and safety have been achieved through preemptive life expectancy and life management of aircraft structures. The crack size inspection capability of the aircraft under analysis is 0.03inch, compared with 0.032inch, which is the lowest of the three vulnerable parts. In addition, the fatigue life analysis results in approximately 1450 operating hours, the lowest of the three vulnerable parts relative to the aircraft's required life of more than 15000 operating hours, which increased the repeat count of the aircraft's initial and re-inspection times, and hence raised the resulting costs and manpower consumption. Finally, the features were improved through structural fitting of the identified three weak parts. The lowest critical crack size was secured at 0.13 through increased structural resistance to generated cracks and increased aircraft safety. The lowest structural fatigue life for cracks occurring during aircraft operation is 25000 operating hours, which are analyzed above the required structural life, resulting in more optimized improvements than the repair costs and excessive fitting range caused by cracks and fractures.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1146-1153
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• 2008

Numerical simulation was carried out to study the trichloroethylene (TCE) degradation by permeable reactive barrier (PRB), and revealed the effect of concentration of TCE, iron medium mass, and concentration of iron-reducing bacteria (IRB). Newly developed model was based on axial dispersion reactor model with chemical and biological reaction terms and was implemented using MATLAB ver R2006A for the numerical solutions of dispersion, convection, and reactions over column length and elapsed time. The reaction terms include reactions of TCE degradation by zero-valent iron (ZVI, Fe$^0$) and ferrous iron (Fe$^{2+}$). TCE concentration in the column inlet was maintained as 10 mg/L. Equation for Fe$^0$ degradation includes only TCE reaction term, while one for Fe$^{2+}$ has chemical and biological reaction terms with TCE and IRB, respectively. Two coupled equations eventually modeled the change of TCE concentration in a column. At Fe$^0$ column, TCE degradation rate was found to be more than 99% from 60 hours to 235 hours, and declined to less than 1% in 1,365 hours. At the Fe$^{2+}$ and IRB mixed column, TCE degradation rate was equilibrated at 85.3% after 210 hours and kept it constant. These results imply that the ferrous iron produced by IRB has lowered the TCE degradation efficiency than ZVI but it can have higher longevity.http://kci.go.kr/kciportal/ci/contents/ciConnReprerSearchPopup.kci#

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.175-179
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• 1979

One of the major problems in tile activated sludge system has been difficulty in separating the microbial solids from the treated effluent and in returning them to the aeration tank. Another problem has been the digestion of the excess activated sludge. In constrast, it has not been difficult to separate the microbial solids from the treated effluent from the biological fixed-film systems(RBC process, Trickling Filter, FAST process). These systems have also featured less sludge production. Recently, it was proposed to experiment with the RESMAS process in order to eliminate the settling tank and sludge concentration facilities and to reduce the quantity of excess sludge for final disposal. The effluent quality could be predicted by .the concept of the maximum accumulation capacity. However, the hydraulic characteristics of the screen media in the RESMAS reactor were not dynamic. The object of the present study is to evalute the sludge accumulation rate and effluent quality prediction in the REMSMAS process designed in the dynamic hydraulic structure. This process can eliminate the final sedimentation tank and sludge concentration tank needed in the RBC, CMAS, Trickling Filter and FAST processes. Also, the effluent quality is desirable to compare with other processes. It appeared that the value of the sludge holding capacity was higher than those of the RESMAS and FAST processes, and the periods of the critical operating time were proportional to the substrate hydraulic loadings.

• Journal of Yeungnam Medical Science
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• v.14 no.2
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• pp.430-442
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• 1997

Due to the lowering of biological functions resulted from old age, the elderly is known to have many different clinical laboratory data compared with the young adults. But, in korea, such study is lacking. This research is to find the differences between the elderly and the young adults, and also to know the sexual differences, by comparing the outcomes of the clinical. laboratory data. Along with that, it is to help clinical usage of the data in the future. The age of the elderly was between 60 and 83(average age 63.8), and that of the young. controls was between 20 and 35. In both sexes, MCV, MCH, ESR, CRP, AST, ALT, ${\gamma}$GTP, ALP, BUN, total cholesterol were significantly higher in the elderly than in the controls. And lymphocyte count(%), total bilirubin, direct bilirubin, total protein, albumin, $T_3$ were significantly lower in the elderly than in the controls(P<0.05). Hemoglobin, Hct, platelet count, $T_4$ were significantly lower only in the male elderly, and eosinophil count(%), creatinine were significantly higher only in the female elderly(P<0.05). HDL cholesterol was significantly higher only in the male elderly(P<0.01). There were no significant difference between two groups regarding WBC count, segment neutrophil count(%), monocyte count(%), TSH. Many clinical laboratory data are different between the elderly and the young adults, and some clinical laboratory data also have sexual differences.

• The Journal of the Korea Contents Association
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• v.16 no.11
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• pp.330-345
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• 2016

The purpose of this study was the children learn character education situation and the desire of parents to recognize there is a purpose. In D city, the data collected was intended for 170 parents percentage of the frequency analysis SPSS program was performed multiple responses cross-validation analysis, and difference. As a result, first, it has the highest awareness of the need for Children Personality care and education of parents interest also highest. It was the concept of holistic education and character education Children can see that the same interpretation in the context of understanding the concept of Children education and Personality contents were understood as a whole. Second, these activities were Children Personality to training status could see that the character education are being made in this result assumed concentration of Children humanity education conducted in the home and work areas of daily life guidance and basic lifestyle at home talking It was made through the division. Children correct behavioral models for character education has given the values of the parent as the parent greatest impact on the formation of the Personality of children. Third, Children need for parent participation of character education should be made a parent education involvement in what is the result of Children character education out and it was found that it should be carried out life guidance program of parent education programs for Children character education.

• The Journal of the Korea Contents Association
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• v.15 no.4
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• pp.373-379
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• 2015

The purpose of this study is to investigate the effect of the degree of mimetic purchase on product satisfaction. In addition the present study aims to investigate the moderating role of the self esteem and public self in the relationship between mimetic purchase and product satisfaction. Taken together, hypothesis 1 is as in the following. H1 : As the degree of mimetic purchase increases, product satisfaction will increase. To reveal the moderating role of the self esteem and public self in this path, 2 research hypotheses are derived as follows: H2 : The effect of mimetic purchase on product satisfaction is moderated by self esteem. H3 : The effect of mimetic purchase on product satisfaction is moderated by public self. Results from an empirical study showed that as the degree of mimetic purchase increases, product satisfaction increase. Thus, H1 is fully supported. And the results showed that the first interaction effect(H2) between the mimetic purchase and the self esteem is significant. Thus, H2 is also supported. But the second interaction effect(H3) has been shown to be not significant.

• Journal of Navigation and Port Research
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• v.30 no.6 s.112
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• pp.439-446
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• 2006

In ship structures many of the structural plates have cutouts, for example, at inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has a cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed In general, actual ship structure adopted reinforcement of stiffener around the cutout in order to preventing from buckling so it need to examine a buckling and ultimate strength behaviour considering a cutout because In many ship yards used class rule for calculating buckling strength but it is difficult to evaluate perforate stiffened plate with random size. In the present paper, we investigated several kinds of perforated stiffened model from actual ship and then was performed finite element series analysis varying the cutout ratio, web height, thickness and type of cross-section using commercial FEA program(ANSYS) under compressive load.