• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.575-585
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• 1997

A daily runoff system was constructed to support decision making for water use in the downstream region of multipurpose dams in the Han River. The daily runoff system used the modified model from NWSRFS by Tabios III et al. (1986), and potential evapotranspiration was computed from Penman equation. DWOPER was used for channel routing. While the North Han River is the main river reach in the channel routing system, the South Han River and the Soyang River became tributaries. The rainfall-runoff model was calibrated and verified for five subbasins. Daily runoffs were simulated with the hydrometeorological data in 1986 and1990. The simulations were performed from April to November, and the sum of computed discharges for seven or thirty days were compared with actual releases of the downstream dams. It showed the average absolute errors of 8.7 ~31.6%. The sum of total discharges were 10% or less. While stage errors were produced by 0.5 m or less at Yoju station in the ease of simulation from April to August in 1986, the errors kept under 0.2 m since September. In the simulation for 1990, we compared two simulation results. One is produced from real internal and downstream boundary conditions and the other is one from internal and downstream boundary conditions fixed arbitrarily. The two cases showed similar results.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.37-45
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• 2009

The experimental study was carried out to evaluate the characteristics of the point load index and the uniaxial compressive strength of inherently anisotropic shale in the laboratory. In the testing program the effects of size and the shape on the point load index were investigated both in the axial and diametral direction. In general, the point load index of the shale was constant when the length/diameter (L/D) ratio of the specimen is greater than 1.0 in the diametral direction. The point load index in axial direction shows slight decrease as the L/D ratio is increased and the corner breakage was observed when L/D ratio is greater than unity. The minimum point load index was observed in the bedding angle of $\beta=15^{\circ}{\sim}30^{\circ}$ in the axial point load tests and of $\beta=30^{\circ}$ in the uniaxial compression tests. The relationship between the point load index and the uniaxial compressive strength was linear to ${\sigma}_c=25.0 I_{s(50)}$ for the specimen with the bedding plane angle, $\beta$ at the range of $0^{\circ}{\sim}90^{\circ}$. On the other hand, this relationship was appeared linear to ${\sigma}_c=14.4 I_{s(50)}$ when the bedding angle, $\beta$ is fixed to 90${^{\circ}}$ and this correlation is much different from ${\sigma}c=22 I_{s(50)}, which is generally applied to the rock specimen with no bedding plane in ISRM (1985). The anisotropic strength with different $\beta$ angle shows the shoulder type and this can be suitably modelled by the corrected Ramamurthy'(1993)s equation with the index value of 'n' equal to 3.0.

• Journal of Technology Innovation
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• v.25 no.3
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• pp.51-82
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• 2017

In terms of both economic growth and social welfare, this paper discusses the optimal proportion and size of basic research budget by adding knowledge stock to an endogenous growth model. On the basis of the modified endogenous growth model, this paper derived an equation that consists of kinds of parameters and suggested this equation as a criterion for determining whether allocated basic research budget has been appropriate. This paper also found that the theoretical optimal ratio between government investment spending and investment in basic research is equal to the ratio between the partial elasticity of output with respect of public capital stock and the partial elasticity of output with respect of knowledge stock. In addition, after the required parameters were specified based on precedent literatures, this paper estimated an optimum size of the basic research budget using the theoretical optimal ratio with official statistical records and compared the estimated size to its actual size. This paper therefore is expected to contribute to budget planning and allocation regarding establishing basic research policy, because the results of this paper presents a useful criterion for optimum level and an approximate size of investment in basic research. However, it should be noted that although the optimal solution is optimal in a economic sense, it may not be the best solution from a practical perspective.

• KSTLE International Journal
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• v.7 no.2
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• pp.27-34
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• 2006

Knudsen number is the ratio of molecular mean free path versus mm thickness and the criterion to determine the flow form. When its value is lower than 0.01, the flow can be assumed to has no slip boundary condition. And in the case that the value is between 0.01 and 10, then the flow has slip boundary condition at both the adjacent walls. The condition of the air flow between the rotating journal and top foil in the air foil bearing is determined by the rotating speed and load, and the Knudsen number is also varied by those values. Because the molecular mean free path is variable to the pressure and temperature, more exact formulation is necessary to understand and analyze the flow regime. In this study, the analysis considering Knudsen number formulated with those variables (pressure, temperature and mm thickness) was executed. The approximate value was examined using the equation to confirm whether the flow has the slip or no-slip boundary condition. From the analytic investigation, it was decided to range approximately 0.01 to 1.0 and the flow can be supposed to have the slip boundary condition. Under the condition of the slip flow, the static characteristics of the air foil bearing were examined using modified Reynolds equations. The results were compared with those considering no slip condition. It shows that the slip condition makes the flow decelerates and the load carrying capacity decreases compared with no slip condition. And as the bearing number and eccentricity ratio increase, the load carrying capacity also increased at both the cases. From this result, it can be supposed that the bearing torque also increases. In the analysis of the dynamic characteristics, the perturbed Knudsen number was taken into consideration. Because the Knudsen number is expressed as the terms of each variable, the perturbed equation can be simply derived. The results of both cases considering and not considering Knudsen number were compared each other. In the case of the direct terms of the stiffness and damping coefficients, the difference between both cases was little and increased as the bearing number and eccentricity ratio increased. And the cross terms have less or more differences.

• Journal of Bio-Environment Control
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• v.3 no.1
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• pp.1-9
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• 1994

Wind load or snow load, acting on agricultural structures is working more sensitive than any other load and therefore plays an important role in determination of design loads of agricultural structures. In this study, unit snow weight, greatest gust speed and depth of snow fall were analyzed and applied to determine the amount of frames. The unit snow weights were statistically classified and calculated in the basis of mean temperature and showed considerable differences between the unit snow weights at below and above -1$^{\circ}C$. Equations for estimating greatest gust speed with fastest wind speed were developed for inland and seaside districts. The calculated values from developed equations were little higher than those from the current equation in general. The difference between the depths of snow cover and snow fall, which shows the possibility of reduction of design loads under the adequate management. Design wind speed estimated by a modified equation suggested the amount of frames less than those by current one, and the depth of snow fall as a design snow depth suggested the amount of frames more than those of snow cover. Therefore, it is very important to select the adequate design values considering the characteristics of agricultural structures.

• Journal of the Korean Chemical Society
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• v.17 no.2
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• pp.85-94
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• 1973

The stability constants of the charge-transfer complexes formed between three derivatives of nitrobenzene, i.e., 1,3,5-trinitrobenzene, m-dinitrobenzene, nitrobenzene and eleven organic molecules such as $\alpha-picoline$, pyridine, dimethylsulfoxide, N, N'-dimethylacetamide, tetrahydrofurane, 1, 4-dioxane, diethyl ether, acetonitrile, propylene oxide, epichlorohydrine, and methyl acetate, have been determined by ultraviolet absorption spectroscopy in carbon tetrachloride solution at 25.0$^{\circ}C$. The parameters of the electrostatic effect ($E_D$) and covalent effect ($C_D$) for the eleven organic compounds have been calculated from the modified equation of the double-scale enthalpy,$logK = E_AC_A+E_DC_D$ and also the shift of C=O vibrational frequency in infrared spectra for N,N'-dimethylacetamide have been measured from the solutions of above organic compounds. The empirical equation, ${\Delta}{\nu}_{C=O} = 37.4-5.47E_D+12.1C_D$, related to the parameters and the frequency shift has been derived. It seems that the stabilities of the complexes principally depend on the covalent effect. Especially it is found that $\pi$ orbitals in molecules, in addition to the parameters, play the important role in forming the charge-transfer complexes.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.719-725
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• 2005

Anaerobic fill time and feeding pattern in SBR operation were investigated to find way of minimizing poor nitrogen removal efficiency in BNR process without external carbon addition. The three types of the modified SBR operations that were CO-SBR, IA-SBR, and SF-SBR were tested by lab-scale and pilot-scale SBR processes($2\;m^3/day$). In addition, practical equation for biological nitrogen removal was suggested and the equation considered the effect of ratio of fill volume over whole SBR volume and the ratio of step-feed in SBR. The denitrification efficiency of the SF-SBR was best among the three SBRs and followed by IA-SBR, and CO-SBR. The efficiency was 95%, 61%, and 19%, respectively. Looking at the change of sludge floc density by the length of anaerobic fill time, the density of sludge floc at 1 hour and 2 hours of anaerobic fill time were greater than 3 hours of one. The floc size distributions were $100{\sim}300\;{\mu}m$ and $200{\sim}400\;{\mu}m$ with respect to anaerobic fill time 2 hours and 3 hours, respectively.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.733-739
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• 2004

Model for optimally dimensioned PE film bag was developed according to fruit size to maintain best quality of 'Fuyu' persimmon in modified atmosphere packaging (MAP) storage based on relationship between quality and oxygen and carbon dioxide in PE film bag. Harvested persimmons were graded into five sizes, and average weights were LL:261, L:217, M:188, S:168, and SS:154 g. Five fruit units of each grade were optimized in five PE film bag sizes of $150{\times}376,\;140{\times}357,\;130{\times}344,\;130{\times}333,\;and\;120{\times}3l8\;mm$. To minimize quality deterioration such as softening and discoloration, optimal oxygen and carbon dioxide concentrations in PE film bag were 0.5-1.0 and 6.0-8.0%, respectively, and optimal thickness of PE film bag according to fruit size were LL:45, L:50, M:55, S:60, and $SS:65\;{\mu}m$. For all fruit sizes, model for PE film bag area $(mm^2)$ was good quadratic simple equation by fruit weight (g): $Y=-4055.707+627.993X_1-0.701{X_1}^2$. Model far optimal oxygen and carbon dioxide (Y) concentration in PE film bag was suited to linear multiple equation by fruit weight $(X_1,\;g)$ and PE film thickness $(X_2,\;{\mu}m)$. Equations for oxygen and carbon dioxide concentrations (%) were $Y=5.798-0.0109X_l-0.0491X_2\;and\;Y=-2.427+0.01927X_l +0.09646X_2$, respectively.

• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1439-1452
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• 2015

Purpose: The purpose of this study was to construct a SEM that would further explain the college adaptation for nursing students. Methods: Model construction was based on the variables; mother attachment, self concept, stress, stress of clinical practice, psychological well-being, coping, and college adaptation. The analysis of data was done with both SPSS 20.0 for descriptive statistics and AMOS 20.0 for SEM. Results: The psychological well-being and coping was found to have a significantly direct effect in predicting college adaptation. In addition, mother attachment, self concept, and stress were found to have a significantly direct effect in predicting college adaptation. The final modified model yielded ${\chi}^2=231.1$ (p <.001), ${\chi}^2/df=2.36$, GFI=.91, AGFI=.86, NFI=.91, PNFI=.73 RMSEA=.07, and CFI=.95. Conclusion: To improve adjustment to college life, it is recommended to have a direct method of developing psychological well-being and coping improvement program to improve mother attachment.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.115-124
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• 2004

According to Sagong and Paik (2003), the side resistance of rock socketed drilled shafts is affected by rock quality, types, uniaxial compressive strength, and confining stress. Their approach based upon the Hoek-Brown criterion provides reasonable predictions of the side resistance. In this study, we propose an equation to calculate the side resistance considering size effects of the shafts and investigate the influence of drilled shaft diameter on the side resistance. A new method employs the modified Hoek-Brown criterion together with an empirical size effect of rock core. From the previous field tests, 12 pile load test results were collected and compared with prediction calculated from the equation proposed in this study. In a given condition, similar results between measurement and estimate are observed. From the parametric study on the GSI, confining stress, uniaxial compressive of intact rock and pile size, it is shown that uniaxial compressive strength is the most influential parameter on the side resistance. Though pile size shows the least influence on the resistance, the size effect is apparent as rock quality increases.