• The Journal of Engineering Geology
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• v.17 no.4
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• pp.655-664
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• 2007

The major geotechnical parameters employed in tunnel design are deformation modulus, Poisson's ratio, friction angle, cohesion, etc. Among these parameters, the deformation modulus is the most significant parameter in tunnel deformation. However, determination of the modulus for rock mass by means of tests is very difficult due to factors affecting including discontinuities and sample size, etc. Thus input values used in the numerical analysis are generally determined by empirical method. A numerical analysis on tunnel was conducted with geotechnical parameters determined through the geological field mapping, laboratory tests, and evaluation of boring data, and some discrepancy between the computed result and tunnel displacements measured was found. Thus, further analyses by changing the deformation modulus of rock mass were performed to determine a relationship between the modulus and computed displacement. Data from two tunnel sites were used to verify the applicability of the proposed method and a correlative equation between deformation modulus and tunnel displacement is proposed. The deformation modulus of rock mass was around 30-40% of young's modulus of intact rock in these cases.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.212-218
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• 2013

Tuff specimens were thermally treated with predetermined temperatures of 200, 400 and $600^{\circ}C$ to construct specimens simulating weathered tuff rocks. Specific gravity, absorption ratio, elastic wave velocity, uniaxial compressive strength, Brazilian tensile strength, Young's modulus, Poisson's ratio and slake-durability index were measured for pre-heated specimens. Heating of rock specimens entailed the degradation of material properties except for slake-durability index. It was found that correlations among P-wave velocity, uniaxial compressive strength, Brazilian tensile strength, Young's modulus and absorption ratio are high. Regression equations which use the P-wave velocity as an independent variable were presented to evaluate uniaxial compressive strength, Brazilian tensile strength, Young's modulus and absorption ratio.

• Geotechnical Engineering
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• v.9 no.1
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• pp.21-30
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• 1993

To know the importance of soil paramters which are used to estimate the deformation and porepressure of soil, the sensitivity for soil parameters in elastic analysis is analyzed. Using the consolidation teat results of several cohesive soils, soil parameters are estimated by back analysis method, and from the parameters the deformations and porepressures of the soil are estimated by elastic analysis, In elastic analysis for soil-deformation and porepressure, the sensitivity for the Young's modulus is large, and the esimation of Young's modulus is more important in pro- portion to the size of stress. Using the measured results during initial short period in small stress, the soil parameters can be correctly estimated by back analysis method. To decrease the iteration number in back analysis and to get the better paramters, the initial measurements in more nodes are required and the more accurate initial measurements are required.

• The Journal of the Acoustical Society of Korea
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• v.10 no.1
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• pp.30-36
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• 1991

Since the Complex Young's Modulus of acoustic materials is a function of frequency under a static load, a cylindrical specimen modelled by rod-like one with losses is used to determine the dynamic characteristics of materials. The specimen is excited into longitudinal vibration at its one end by shaker and at the other end, loaded by a mass corresponding to the desired static load and thus the transfer function of specimen is measured. This transfer function method is analyzed theoretically and experimentally over a frequency range of 50 Hz to 20 KHz. The analysis includes the measurability of the transfer function, the frequency range of the method and lateral motion effect.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.67-74
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• 2016

The yield shear strength of bolt connection in glass fiber reinforced glulam was predicted using a design-based equation, and was compared to the empirical yield shear strength. For the predicted equation, the mechanical properties of member (the elastic modulus, Poisson's ratio, shear modulus) was tested. The fracture toughness factor ($K_{ft}$) of glass fiber reinforced glulam was reflected to the revision of the design equation of bolted connection. The compressive strength properties to grain direction was influenced by annual ring angle and width of lamina. Compared with the revised yield shear strength of reinforced glulam, it was tended to be similar to the empirical yield shear strength on the diameter of bolt and the reinforcements. The revised yield shear strength from proposed formula of KBC was most appropriately matched in the bolt connection of the glass fiber reinforced glulam.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1207-1212
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• 2015

In this paper, we propose three-dimensional (3D) visualization and recognition techniques of micro-objects under photon-starved conditions using photon counting integral imaging microscopy. To capture high resolution 2D images with different perspectives in the proposed method, we use Synthetic Aperture Integral Imaging (SAII). Poisson distribution which is mathematical model of photon counting imaging system is used to extract photons from the images. To estimate 3D images with 2D photon counting images, the statistical estimation is used. Therefore, 3D images can be obtained and visualized without any damage under photon-starved conditions. In addition, 3D object recognition can be implemented using nonlinear correlation filters. To prove the usefulness of our technique, we implemented the optical experiment.

• The Korean Journal of Applied Statistics
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• v.24 no.3
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• pp.485-494
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• 2011

When the observations can take only the non-negative integer values, it is called the count data such as the numbers of car accidents, earthquakes, or insurance coverage. In general, the Poisson regression model has been used to model these count data; however, this model has a weakness in that it is restricted by the equality of the mean and the variance. On the other hand, the count data often tend to be too dispersed to allow the use of the Poisson model in practice because the variance of data is significantly larger than its mean due to heterogeneity within groups. When overdispersion is not taken into account, it is expected that the resulting parameter estimates or standard errors will be inefficient. Since coverage is the main issue for insurance, some accidents may not be covered by insurance, and the number covered by insurance may be zero. This paper considers the zero-inflated model for the count data including many zeros. The performance of this model has been investigated by using of real data with overdispersion and many zeros. The results indicate that the Zero-Inflated Negative Binomial Regression Model performs the best for model evaluation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.325-330
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• 2018

This paper, following the shape parameters of the minimax distribution, describes the special form of the beta distribution, the Minimax distribution, as a function of the shape parameters for the software reliability model based on the non-homogeneous Poisson process. Characteristics and usefulness were discussed. As a result, the case of the shape parameter 1 of Minimax distribution than less than and greate in mean squared error is the smallest, in determination coefficient, appears to be high, the shape parameter 1 of Minimax distribution regard as an efficient model. The estimated determination coefficient of the proposed model is estimated to be more than 95%, which is a useful model in the field of software reliability. Through this study, software design and users can identify the software failure characteristics using mean square error, decision coefficient, and confidence interval can be used as a basic guideline.

• Tunnel and Underground Space
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• v.24 no.4
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• pp.325-333
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• 2014

Hydraulic fracturing is the key technology for production of shale gas, which is one of the major unconventional resources. Brittleness index is one of the most important mechanical properties which determine the efficiency of hydraulic fracturing. It was required that the production of shale gas increases with more brittle behavior. Confusingly, there are numerous definitions available for brittleness of rock. This paper summarizes various definitions of brittleness index, and presents correlation analysis of the brittleness indices by using the laboratory experimental results of 48 shale specimens in Korea. Generally, it shows a very weak positive correlation between the brittleness index ($B_1$) which is the ratio of uniaxial compressive strength to tensile strength and the brittleness index ($B_3$) which is calculated by using the Youngs modulus and Poisson's ratio. In addition, the role of Poissons ratio is not clear in defining brittleness indices. In conclusion, standardization of definition for brittleness index is required to apply it to hydraulic fracturing as a parameter for predicting the efficiency.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.107-111
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• 2008

As high-rise buildings with 100 or more stories are being constructed, it is inevitable to use high-performance materials including high-performance concrete. What is most important in high-performance concrete is extremely high strength in order to reduce the section of members in high-rise buildings. During the last several years, there have been active researches on Ultra-high-strength concrete. While these researches have been mostly focused on strength development, however, other accompanying physical properties have not been studied sufficiently. Thus, this study purposed to obtain and analyze data on the physical-mechanical properties of Ultra-high-strength concrete through experiments and to use the results as basic information on required performance of concrete used in high-rise buildings.