• Advances in environmental research
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• v.12 no.1
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• pp.17-40
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• 2023

This article presents studies of the adsorption process in a continuous system of fluoride solutions at a concentration of 30 mg/L using a bone char packed in fixed-bed columns, as well as regeneration studies in the same system using HNO₃, HCl and NaOH at 0.01, 0.1 and 1 M. The Thomas Model, Artificial Neural Networks (ANNs), Numerical Integration and Mass Transfer Zone were used for the modeling of asyemmetrical breakthrough curves obtained from the fluoride adsorption on bone char. The maximum adsorption capacity of the breakthrough curves was estimated, and various design parameters of the columns were obtained for the different operating conditions. Results showed that an improvement in the modeling capabilities of the Thomas model can be obtained using ANNs. Moreover, ANNs are useful for determining reasonable and accurate design parameters of packed-bed adsorption columns. This modeling approach can be useful for the process system engineering of dynamic adsorption systems involved in the field of water treatment and purification. It is important to highlight that the obtained results indicate that, when using HCl or HNO₃ at a concentration of 0.1 M, a large number of adsorption-desorption cycles are obtained and, therefore, the highest values of adsorption capacity, which leads to a reduction in operation costs.

• Journal of The Korea Institute of Healthcare Architecture
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• v.25 no.4
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• pp.93-104
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• 2019

Purpose: To establish the building guidelines and to analyze the function of Regional Public Hospitals, the survey was conducted primarily on the current status focusing on the location and relationship of the department, area composition ratio, area per bed, and area per operating room. Methods: The research methods of this paper are as follows. 1) A literature survey on the function of the operating and related departments, 2) A drawing analysis for spatial composition and net area calculation. Results: The area of the Operation Department in the Regional Public Hospitals with 200 to 300 beds are as follows. Area ratio: 3.35%, area per Bed: 2.53㎡/bed, the number of beds per operating room: 64.37bed, area per operating room: 146.46㎡/n, area per operating room by plan type: integration corridor 133.84㎡/n, separation corridor 184.82㎡/n. Implications: This paper analyzed data on the current state of Operation Departments for setting up the function and role for the Regional Public Hospital. In the future, it is also required to provide size that takes into account user behavior and the user's psychological aspect in order to suggest appropriate area.

• Solar Energy
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• v.14 no.2
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• pp.91-101
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• 1994

Heat release characteristics of a CaO packed bed reactor which is used for a chemical heat storage device has been studied. We employed Cu-plate fins to release the heat of reaction of the CaO packed bed inside the reactor fast and effectively. Two-dimensional analysis of unsteady state heat flow inside the bed was performed as a function of time and under various conditions of the Cu-plates. It is noted that the time required to release the heat of reaction with Cu fins is reduced more than twice fast compared to that without Cu fins. That was largely dependent upon the number of Cu-plate, as well.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.307-312
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• 2020

Fluidized bed reactors operated in subatmospheric pressure has been focused because several industrial applications such as vacuum drying and plasma cvd requires reduced pressure fludization. However, the hydrodynamics of fluidized beds in subatmospheric pressure has not been extensively investigated. The pressure drop in the fluidized bed has been measured with variation of downstream pressures from 1.33 to 101.3 kPa in the shallow and deep fluidized beds under the sub-atmospheric pressures. The obtained minimum fluidization velocity of powders is a function of pressure due to the changes of gas density and mean free path. We can experimentally determine the critical Knudsen number and the critical pressure to define the slip regime significantly to influence the hydrodynamics of fluidized beds.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.3 s.116
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• pp.79-90
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• 2006

Tamarix chinenis blooms twice a you and its flowers, branches and leaves make the adjustment of tree shape. Propagation methods and growth characteristics of T. chinensis were studied in order to ascertain its potential use as one of vegetation resources for coast forestation and landscaping. The study results indicated that 1 or 2 you old hard wood cuttings showed higher rooting ratio than greenwood or semi hard wood cuttings. One to one mixture between vermiculite and pearlite appeared to be the best for bed soil, and sea sand and silt(loess) mixture was the next. Sea sand and granitic soil followed after. In terms of seasonal differences, spring cuttings showed the best rooting ratio, root number, and root length. Fall cuttings followed after spring cutting, and summer cuttings showed worst results regarding rooting ratio, root number, and root length. The best rooting promotion effects of growth regulators were observed with sea sand bed soils. There was no significant difference among growth regulators in terms of rooting and shoot growth. Low concentration below 100 ppm of growth regulators was enough for rooting promotion effect. In general, the number and mean length of roots and shoots were showed the excellent records in the sites with high rooting ratio. The study result strongly showed that T. chinensis can be considered as a suitable tree for coast forestation and landscaping because of its easy cutting propagation and rapid growth on saline lands.

• Korea Journal of Hospital Management
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• v.14 no.2
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• pp.1-20
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• 2009

The purpose of this study is to find the determinant variables to make profitability in regional public hospitals. The data come from financial statements and annual reports of 34 regional public hospitals for five years (from year 2003 to year 2007). The T or F-test and hierarchical multiple regression analysis are used. The dependant variables are the profitability indicators, ordinary income to total asset and operating margin to gross revenue, and the independent variables are general characteristics, diagnosis and treatment patterns, financial and public benefits. The findings of this study are summarized as follows. First, Variables affecting the profitability indexes revealed from DEA results is the bed occupancy rate, number of hospitalized patients to outpatients, ratio of first medical examination for outpatients, number of daily patients per medical specialist, labor cost per patient and managerial expenses per patient. Second, the ordinary income to total asset representing the asset usage performance is affected by the average hospitalized days, bed occupancy rate, labor cost per patient and ratio of patients with medical insurance coverage. Third, the operating martin to gross revenue obtained from the actual operations of hospitals has its significance with the bed occupancy rate, number of hospitalized patients to outpatients, managerial expenses per patient and public benefit indicator. This study has some restriction not to use pannel data analysis, although it used data for five years. Accordingly, various additional studies should be done to supplement such problems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1264-1270
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• 2006

In this study, semi-two dimension numerical model(GSTARS 2.1 model) were applied to study on the hydraulic and sedimentologic characteristics of downstream channel section in Dal stream. GSTARS 2.1 model was applied for the four selected sediment transport formulas(Meyer-Peter and Muller, Acker and White's, Engelund and Hanson, Yang formula) from 1984 to 1992 measured data on each section. The simulation results of Meyer-Peter and Muller formula for long-term bed changes are good when compared to the measured data. When quantitatively compared, it appears that the results data is relatively underestimated compared to the 1992 measured data on each section. Using Meyer-Peter and Muller formula, analyse the effects of bed changes by stream tube number.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.227-233
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• 2013

A total of 25 species, 3,880 individuals and 3,145.1 g of fishes were collected by a surf net from the eelgrass bed in Minyang. Most fishes collected in the eelgrass bed belong mainly to small fish species or juveniles. The dominant fish species were Gymnogobius heptacanthus, Rudarius ercodes, Pholis nebulosa, Chaenogobius gulosus, and Gymnogobius castaneus which accounted for 89.1% of total number of individuals collected. The number of individuals and biomass were higher from June to September when the water temperature was high. However, both the number of individuals and species showed the lowest from January and February. Highest species diversity index (H') was observed in April, 2012.

• Journal of Environmental Science International
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• v.20 no.5
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• pp.555-564
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• 2011

This study examines the potential restoration of abandoned channels of the Mangyeong River in South Korea. To analyze the morphological changes and equilibrium conditions, a flow duration analysis was performed to obtain the discharge of 255 m3/s with a recurrence interval of 1.5 year. It is a gravel-bed stream with a median bed diameter of 36 mm. The reach-averaged results using HEC-RAS showed that the top width is 244 m, the mean flow depth is 1.11 m, the width/depth ratio is very high at 277, the channel velocity is 1.18 m/s, and the Froude number is also high at 0.42. The hydraulic parameters vary in the vicinity of the three sills which control the bed elevation. The total sediment load is 6,500 tons per day and the equivalent sediment concentration is 240 mg/l. The Engelund-Hansen method was closer to the field measurements than any other method. The bed material coarser than 33 mm will not move. The methods of Julien-Wargadalam and Lacey gave an equilibrium channel width of 83 m and 77 m respectively, which demonstrates that the Mangyeong River is currently very wide and shallow. The planform geometry for the Mangyeong River is definitely straight with a sinuosity as low as 1.03. The thalweg and mean bed elevation profiles were analyzed using field measurements in 1976, 1993 and 2009. The measured profiles indicated that the channel has degraded about 2 m since 1976. The coarse gravel material and large width-depth ratio increase the stability of the bed material in this reach.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.711-723
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• 2000

Existing equations of bed load transport have large variations in their forms and adopt different variables so that it is very difficult to understand the characteristics of each equation. Different sets of measurement data have been employed for the development of various equations, and the comparison between them is completely dependent on the choice of the data for the verification. Several equations seem to have some defects in their basic assumptions. Various non-dimensional physical numbers directly associated with the mechanism of bed load transport are related with each other, and one of them is chosen for the unification of the form. Good ideas introduced in a certain equation are employed for the refinement of other equations. Then optimum values of empirical parameters have been determined by using the data collected by Brownlie(1981) and a new bed load equation has been developed, which is considered widely valid and relatively very accurate.curate.