• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.287-293
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• 2019

Domestic thermal power plant fly ash is at a situation which emissions are increasing every year. Comparing to Fly Ash, Bottom Ash is only 15 %, but it's recycling rate is low, so most of them is being buried in the ground. However, landfill site of every power plant is full, and the construction of a new landfill is difficult. To solve this problem, the best solution is to use Bottom Ash as a landfill of large-scale civil engineering projects. The purpose of this study was to investigate the compression strength behavior characteristics of weak clay and uniaxial compression test to examine the applicability of surface soil solidification method of mixed soils mixed with industrial waste coal ash and weak clay which is buried in bulk. As a result of the test, the fluidity of the Mixed soil with clay + bottom ash + cement was improved to 200 mm at the water content of 91-92 %. The uniaxial compressive strength was also good for the mixed soils (clay + bottom ash + cement) meeting the required strength of 159 kN/㎡ at 28 days. However, the other samples did not meet the required strength. In this study, the prediction equations for the compression strength behavior by cement and curing period were presented.

• Journal of the Korean Institute of Gas
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• v.5 no.1
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• pp.60-72
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• 2001

This paper presents the user-interactive productivity analysis model based on material balance as well as deliverability equations equipped with EOS model to perform a productivity analysis for Gorae V structure, Donghae-1 gas field. This model is designed to be able to analyse the productivity in the case of reservoir contacting with the aquifer. Also, in order to investigate the effect of condensation on productions, condensation phenomenon is considered as an apparent skin effect in the computation of bottomhole pressure from average reservoir pressure. By utilizing the developed model, we investigate the productivity analysis for B2 layer of Garae V structure with the various production cases in volumetric and non­volumetric reservoirs that contact with aquifer. From the results in the case of 5500 MMSCF/year of production and reservoir-aquifer contacting angle 270$^{\circ}C$ with aquifer size of 10 times greater than reservoir, B2 layer could maintain peak production rate even after 8.5 years of production by considering the bottomhole pressure which is estimated above the operating pressure of 1298 psia. It is also found that condensate will be formed after 1100 days of production and existed throughout the reservoir at 1270 days. Note that the computed reservoir pressure of B2 layer is maintained sufficiently high enough for production due to the water influx into the reservoir, and skin effect caused by condensation is not significant.

• Journal of Soil and Groundwater Environment
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• v.10 no.1
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• pp.26-34
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• 2005

The effects of soil-chemical contact time (aging) on sorption and desorption of atrazine were studied in soil slurries because aging is an important determinant affecting on the sorption and desorption characteristics of organic contaminants in the environment. Sorption isotherm and desorption kinetic experiments were performed, and soilwater distribution coefficients and desorption rate parameters were evaluated using linear and non-linear sorption equations and a three-site desorption model, respectively. Aging time for sorption of atrazine in sterilized soil slurries ranged from 2 days to 8 months. Atrazine sorption isotherms were nearly linear $(r^2\;>\;0.97)$ and sorption coefficients were strongly correlated to soil organic carbon content. Sorption distribution coefficients $(K_d)$ increased with increasing aging in all soils studied. Sorption non-linearity did not increase with increased aging except for the Houghton muck soil. Desorption profiles were well described by the three-site desorption model. The equilibrium site fraction $(f_{eq})$ decreased and the non-desorbable site fraction $(f_{nd})$ increased as a function of aging time in all soils. In all soils studied, it was found that when normalized to soil organic matter content the concentration of atrazine in desorbable sites was comparatively constant, whereas that in non-desorbable site increased as aging increased.

• Economic and Environmental Geology
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• v.47 no.3
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• pp.237-246
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• 2014

In this study, it is estimated how many changes of macroeconomic variables are happened under the proposition of import substitution of mining products 1% using macroeconometric input-output model. For this, used macroeconometric input-output model is composed of 141 behavioral equations representing the macroeconomy structure. In general, macroeconometrics models are constructed mainly on the side of the expenditure then it is not easy to estimate the effects of the shocks occurred from industry level. To mitigate that, this study tries to construct a macroeconometric input-output model. Macroeconometrics model which is useful to estimate the effects of macroeconomic shocks, economic policy and more, in this study, is linked with input-output table through the NDI(national disposable income) derived from compensation of employee. And this paper presents the estimation results of import substitution effects of mining products on Korean economy. As a results, GDP is increased 0.00073%, gross labor employed 0.00029%, current balanace 0.00010% and unemployment rate is mitigated 0.00233%.

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.479-484
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• 1986

Two different types of solar collector for farm dryer- the flatplate type and the modified tubular type-were constructed and analyzed on their performances. The transparent plastic film, black painted galvanized iron sheet and black vinyl film were used for the cover and absorber of the flat-plate types. The simplified tubular type was constructed with transparent films for the cover and black vinyl films for the absorber Two elliptical iron rings were used to form a tubular shape through which air could pass. No remarkable differences were found in thermal efficiences between the absorbers made with galvanized iron sheet and black vinyl film. The average thermal efficiencies of the solar collectors were 42.8%(max.48.2%, min.38.2%) for flat plate type and 22.971 (max. 25.4%, min. 14.8%)) for tubular one. The empirical equations were proved to be applicable to the prediction of temperature elevation. The tubular solar heat collector was successfully applied to red peppers drying as a practical farm dryer. The drying rate was almost doubled compared to a conventional sun drying.

• Clinical and Experimental Pediatrics
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• v.50 no.9
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• pp.862-867
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• 2007

Purpose : The impulse oscillometry (IOS) is applicable to young children because it requires minimal cooperation and a non-invasive method to measure the mechanics of respiratory system. This study aimed to develop the reference values in school-aged children in Korea, using IOS which is a modification of forced oscillation technique (FOT). Methods : Measurements were performed in 92 previously untrained healthy children, aged 7 to 12 years old, using IOS. We analyzed the relationships between the data about their age, height, weight, body surface area (BSA), body mass index (BMI) and the result of IOS using the linear regression test. Results : The success rate of IOS was 92.4%. Stepwise multiple regression of resistance of respiratory system (Rrs) and reactance of respiratory system (Xrs) in natural form for age, height, weight, BSA, BMI showed that height was the most significant predictor and altogether of 5 variables explained the Rrs and Xrs most. Our regression equations at multiple frequencys were comparable to published reference values, especially about the Rrs obtained at 5 Hz. Conclusion : IOS is a feasible method to measure the respiratory resistance in untrained children. We got the reference values using IOS and it seems to be useful to diagnose a variety of respiratory diseases.

• Clinical and Experimental Pediatrics
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• v.54 no.2
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• pp.64-68
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• 2011

Purpose: The normal values for lung resistance and lung capacity of children, as determined by impulse oscillometry (IOS), are different for children of different ethnicities. However, reference values there is no available reference value for Korean preschool children have yet to be determined. The aim of the present study was to determine the normal ranges of IOS parameters in Korean preschool children. Methods: A total of 133 healthy Korean preschool children were selected from 639 children (aged 3 to 6 years) who attended kindergarten in Seongnam, Gyeonggi province, Korea. Healthy children were defined according to the European Respiratory Society (ERS) criteria. All subjects underwent lung function tests using IOS. The relationships between IOS value (respiratory resistance (Rrs) and reactance (Xrs) at 5 and 10 Hz and resonance frequency (RF)) and age, height, and weight were analyzed by simple linear and multiple linear regression analyses. Results: The IOS success rate was 89.5%, yielding data on 119 children. Linear regression identified height as the best predictor of Rrs and Xrs. Using stepwise multiple linear regressions based on age, height, and weight, we determined regression equations and coefficients of determination ($R^2$) for boys ($Rrs_5=1.934-0.009{\times}Height$, $R^2$=12.1%; $Xrs_5=0.774+0.006{\times}Height-0.002{\times}Age$, $R^2$=20.2% and for girls $(Rrs_5=2.201-0.012{\times}Height$, $R^2$=18.2%; $Xrs_5=-0.674+0.004{\times}Height$, $R^2$=10.5%). Conclusion: This study provides reference values for IOS measurements of normal Korean preschool children. These provide a basis for the diagnosis and monitoring of preschool children with a variety of respiratory diseases.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.3
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• pp.291-303
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• 2016

Recently, various forms of diverging sections in tunnels have been designed as the demand for underground passageway in urban areas increases. Therefore, the complexity of the ventilation system in tunnels with diverging sections requires a ventilation analysis method different from the conventional method for the straight tunnels. None of the domestic and foreign tunnel ventilation design standards specifies the method for the ventilation network analysis, and the numerical analysis methods have been most widely used. This paper aims at reviewing the ventilation network analytical method applicable as the design standard. The proposed method is based on the characteristic equations rather than the numerical analysis. Thanks to the advantages of easy application, the Hardy-Cross method has been widely applied in the fields of mine ventilation and tunnel ventilation. However, limitations with the cutting errors in the Taylor series expansion and the convergence problem mainly caused by the mesh selection algorithm have been reported. Therefore, this paper examines the applicability of the ventilation analysis method for network-type tunnels with the gradient method that can analyze flow rate and pressure simultaneously without the configuration of mesh. A simple ventilation analysis method for network-type tunnels is proposed.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.10
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• pp.1567-1574
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• 2007

A study was carried out to study the response of total purine derivatives (PD) excretion in urine to determine microbial N (MN) supply at four fixed levels of feed intake (namely 95, 80, 60 and 40% of voluntary intake). The crossbred (CB) calves were allocated according to a $4{\times}4$ Latin Square Design and fed wheat straw and concentrate (1:1). The rate of PD excretion (mmol/d) as a linear function of feed intake was 15.85/kg DMI and 20.12/kg DOMI. Based on the endogenous and PD excretion rates obtained in this study, a relationship between daily urinary PD excretion (Y, mmol) and daily microbial protein supply (X, mmol) was developed for crossbred calves as Y = 0.83X+0.296 kg $W^{0.75}$. The derived microbial N values using this equation differed (p<0.001) among the 4 groups and was the highest in L-95 followed by L-80, L-60 and L-40. The relationship between urinary nitrogen loss (Y, g/d) and DOMI (X, kg/d) was established as: Y = 6.038X+21.753 ($r^2$ = 0.663, p<0.01). When urinary excretion of PD (Y, mmol/d) was plotted against intake of DM and DOM (X, kg/d), the equations obtained were: Y = 7.1711X+8.674 ($r^2$ = 0.889, p<0.01) and Y = 12.434X+7.683 ($r^2$ = 0.896, p<0.01), respectively. The proportional contribution of allantoin and uric acid to total PD remained stable irrespective of level of feed intake. Similarly, urinary excretion of creatinine did not differ (p>0.05) between animals fed at different levels. The MN supply was the highest to animals at intake levels L-95, and decreased linearly with corresponding decrease in feed intake. However, the MN supply when expressed per kg DOMI remained statistically (p>0.05) similar irrespective of level of intake. The results revealed that the excretion of urinary purine derivatives were positively correlated with the level of feed intake as well as rumen microbial supply and thus it could be a good indicator for measuring the microbial protein supply and nutritional status of animals.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.663-672
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• 2009

In this studies, the adsorption test using Chlorella pyrenoidosa was conducted to examine the effect of Pb adsorption according to various immobilized methods such as Ca-alginate, K-carrageenan, and Polyacrylamide. From the results, the duration to need to reach adsorption equilibrium was delayed according to the immobilization. And, the higher adsorption capacity of immobilized Chlorella pyrenoidosa was represented in the higher concentration of Pb, the smaller amount of immobilizing agent, and the higher pH of solution. The maximum adsorption capacity of Pb was shown in the adsorption test using Chlorella pyrenoidosa immobilized with Ca-alginate even though it was sensitive pH. The adsorption results properly represented with Freundlich isotherm equations. And, pseudo second-order chemisorption kinetic rate equation was applicable to all the biosorption data over the entire time range. The FT-IR analysis showed that the mechanism involved in biosorption of Pb by Chlorella pyrenoidosa was mainly attributed to Pb binding of carbo-acid and amide group. Adsorbed Pb on immobilized Chlorella prenoidosa was easily desorbed in the higher concentration of desorbents(NTA, HCl, EDTA, $H_2SO_4,\;Na_2CO_3$). Among the several desorbents, NTA showed the maximum desoption capacities of Pb from Chlorella pyrenoidosa immobilized with Ca-alginate and K-carrageenan and EDTA was the most effective in Chlorella pyrenoidosa immobilized with polyacrylamide. The desoprtion efficiency in the optimum condition was 90.0, 83.0, and 80.0%, respectively.