• Environmental and Resource Economics Review
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• v.17 no.1
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• pp.121-146
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• 2008

The purpose of this paper IS to estimate efficiency and loss of productivity under environmental regulation, and analyze the environmental efficiency index empirically. Using the panel data for 20 member countries of OECD during 1985~1999, environmental efficiency index can be constructed by comparing the production processes under alternative assumptions of disposability, by using a hyperbolic measure of productive efficiency. As a result of estimation for the environmental efficiency index, EE of OECD countries gradually shows a downward trend. In terms of the treatment of pollutants, Japan, Germany and France are countries that have a considerable burden in getting rid of the pollutants. In case of EE, Korea displayed high environment efficiency, but in the latter half of the 1990's, the environmental efficiency of Korea became slightly worse. During the same period, Korea had a burden in dealing with NOx just like the other OECD countries.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.268-275
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• 2017

The photosynthetic rates of crops depend on growth environment factors, such as light intensity and temperature, and their photosynthetic efficiencies vary with growth stage. The objective of this study was to compare two different models expressing canopy photosynthetic rates of romaine lettuce (Lactuca sativa L., cv. Asia Heuk romaine) using three variables of light intensity, temperature, and growth stage. The canopy photosynthetic rates of the plants were measured 4, 7, 14, 21, and 28 days after transplanting at closed acrylic chambers ($1.0{\times}0.8{\times}0.5m$) using light-emitting diodes, in which indoor temperature and light intensity were designed to change from 19 to $28^{\circ}C$ and 50 to $500{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. At an initial $CO_2$ concentration of $2,000{\mu}mol{\cdot}mol^{-1}$, the canopy photosynthetic rate began to be calculated with $CO_2$ decrement over time. A simple multiplication model expressed by simply multiplying three single-variable models and a modified rectangular hyperbola model were compared. The modified rectangular hyperbola model additionally included photochemical efficiency, carboxylation conductance, and dark respiration which vary with temperature and growth stage. In validation, $R^2$ value was 0.849 in the simple multiplication model, while it increased to 0.861 in the modified rectangular hyperbola model. It was found that the modified rectangular hyperbola model was more suitable than the simple multiplication model in expressing the canopy photosynthetic rates affected by environmental factors (light Intensity and temperature) and growth factor (growth stage) in plant factory modules.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.93-101
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• 2020

In order to predict the nonlinear behaviour of the soil, the elasto-plastic hyperbolic model was selected, which was considered to be relatively simple and highly predictable. The soil parameter determination and the behavior analysis program were developed by formalizing the functions related to the constitutive model. Each soil parameter was determined from the results of the drained triaxial compression tests of Baekma river sand with the change of relative density. The stress-strain behavior was predicted using the soil parameters determined under each condition. As a result, the deviator stress for the axial strain is verified to have a good match between the measured value and predicted value at each relative density. In the relationship between the volumetric stain and the axial strain, when the relative density is loose, the measured value and predicted value tend to match, and when relative density is dense, the predicted value of the volumetric strain appears somewhat smaller than the measured value due to the limitation of the constitutive model.

• Journal of the Korean GEO-environmental Society
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• v.19 no.12
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• pp.47-58
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• 2018

Duncan & Chang(1970) proposed the Duncan-Chang model that a linear relation of transformed stress-strain plots was reconstituted from a nonlinear relation of stress-strain curve of triaxial compression test using hyperbolic theory so as to estimate an initial tangent modulus and ultimate deviator stress for the soil specimen. Although the transformed stress-strain plots show a linear relationship theoretically, they actually show a nonlinearity at both low and high values of strain of the test. This phenomenon indicates that the stress-strain curve is not a complete form of a hyperbola. So, if linear regression analyses for the transformed stress-strain plot are performed over a full range of strain of a test, error in the estimation of their linear equations is unavoidable depending on ranges of strain with non-linearity. In order to reduce such an error, a modified regression analysis method is proposed in this study, in which linear regression analyses for transformed stress-strain plots are performed over the entire range of strain except the range the non-linearity is shown around starting and ending of the test, and then the initial tangent modulus and ultimate deviator stresses are calculated. Isotropically consolidated-drained triaxial compression tests were performed on compacted weathered soil with a modified Proctor density to obtain their model parameters. The modified regression analyses for transformed stress-strain plots were performed and analyzed results are compared with results estimated by 2 points method (Duncan et al., 1980). As a result of analyses, initial tangent moduli are about 4.0% higher and ultimate deviator stresses are about 2.9% lower than those values estimated by Duncan's 2 points method.

• Geotechnical Engineering
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• v.10 no.4
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• pp.83-102
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• 1994

For estimation of Ko value depending upon the stress history of dry sand, a new type of Ko oedometer apparatus is devised, and the horizontal earth pressure is accurately measured. For this study, 2 types of one-cyclic Ko loading/unloading models have been studied experimentally using four relative densities of the sand. The results obtained in this test are as follows Kon, the coefficient of earth pressure at rest for virgin loading is a function of the angle of internal friction of the sand and is determined as Kon=1-0.914 sin, Kou the coefficient of earth pressure at -rest for virgin unloading is a function of K. and overconsolidation ratio(OCR), and is determined as Kou : Kon(OCR)". The exponent u, increases as the relative density increases. Ko,, the coefficient of earth pressure at rest for virgin reloading decreases in hyperbola type as the vertical stress, cv', increases. And, the stress path at virgin reloading lends to the maximum prestress point, independent upon the value of the minimum unloading stress. The gradient of this curve, mr, increases as OCR increases.ases.

• Geotechnical Engineering
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• v.13 no.6
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• pp.95-106
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• 1997

A pressuremeter is an expandable tube which is placed in the soil, and then expanded under controlled condition against the soil. From this test a pressure expansion curve of the soil can be obtained. However soil disturbance during the test has significant influence on the results of tests. A general governing equation for pressuremeter test can be theoretically derived on the basis of the hyperbolic soil model and the cavity expansion theory. The curve fitting technique was used to establish the pressure-strain curve without disturbance of soil during testing. This interpretation makes use of both the loading and unloading portions of the test. An interpretation methodology is described and illustrated with pressuremeter test data carried out in the weathered granitic soil to estimate initial shear modulus. Standard penetration test is a very common site investigation technique in Korea. Therefore the blow counts of standard penetration test are discussed by comparing them with initial shear modulus.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11C
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• pp.702-711
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• 2011

In this paper, we derived a closed-form equation of a Best Linear Unbiased Estimator (BLUE) and its Crammer-Rao Lower Bound (CRLB) for the estimation of the position of the emitter based on the Time Difference of Arrival (TDOA) teclmique. The BLUE and CRLB were derived for the case of estimating 2 dimensional position of the emitter with 3 base stations or sensors, and for this purpose, we nsed an approximated equation of the TDOA hyperbola equation obtained from the first order Taylor-series after setting the reference points of the position. The derived equation can be used for any kind of noises which are uncorrelated in each other in the TOA measurement noises and for a white Gaussian noise also.

• Geotechnical Engineering
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• v.13 no.3
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• pp.63-76
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• 1997

To investigate the engineering characteristics of crushed rockfill material, the large-scaled triaxial tests have been carried out, The rpckfill is made from the greywacke, and the 3 parallel gradations with different maximum particle size(dmu=38.1mm, 25.4mm and 19.1mm) were designed for the test. The dimension of the specimen is 300mm in diameter and 600mm in height, and the applied confining stress varied from 5t/$51.6^{\circ}$ to 60t/$51.6^{\circ}$. The test results show that the influence of the maximum particle size on the stress -strain r$51.6^{\circ}\; to\; 40.5^{\circ}$ when the confining stress increases from 5t/$51.6^{\circ}$ to 60t/$51.6^{\circ}$ The hyperbolic parameter values estimated from the test result for rockfill are much different from the recommended values by Duncan et. at(1980) for GW and GP material, especially in the $\phi$ ad K-values.

• Journal of Astronomy and Space Sciences
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• v.2 no.1
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• pp.19-33
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• 1985

The singularities of differential Newtonian equation of motion in three body problem cause the loss of accuracy and the considerable increase of the computer time. These singularities could be eliminated during the process of regularization to transform the independent variables and the coordinate of Newtonian equations of motion. In this study, we calculated the positions and velocities of three body along the time scale to find out the unique solution of regularized Newtonian equations of motion with the $5^{th}$ order Runge-Kutta method by assuming the suitable initial velocities and positions. As the results of these calculations it is shown that the tripe stellar system eventually distintegrated, two of them formed a binary, and the last one escaped from this system with a hyperbolic orbit. This may suggest one possible explanation for the binary formation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.789-794
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• 2017

Subthreshold current model is presented using analytical potential distribution of junctionless cylindrical surrounding-gate (CSG) MOSFET and threshold voltage shift is analyzed by this model. Junctionless CSG MOSFET is significantly outstanding for controllability of gate to carrier flow due to channel surrounded by gate. Poisson's equation is solved using parabolic potential distribution, and subthreshold current model is suggested by center potential distribution derived. Threshold voltage is defined as gate voltage corresponding to subthreshold current of $0.1{\mu}A$, and compared with result of two dimensional simulation. Since results between this model and 2D simulation are good agreement, threshold voltage shift is investigated for channel dimension and doping concentration of junctionless CSG MOSFET. As a result, threshold voltage shift increases for large channel radius and oxide thickness. It is resultingly shown that threshold voltage increases for the large difference of doping concentrations between source/drain and channel.