• Structural Engineering and Mechanics
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• v.82 no.6
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• pp.785-799
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• 2022

The effect of earthquakes in earthquake resistant structure design stages is influenced by the highest ground acceleration value, which is generally a strength-based approach in seismic codes. In this context, an energy-oriented approach can be suggested as an alternative to evaluate structure demands. Contrary to the strength-based approach, the strength and displacement demands of the structure cannot be evaluated separately, but can be evaluated together. In addition, in the energy-oriented approach, not only the maximum effects of earthquakes are taken into account, but also the duration of the earthquake. In this respect, it can be said that the use of energy-oriented earthquake parameters is a more rational approach besides being an alternative. In this study, strength and energy-oriented approaches of earthquake parameters of 11 different periods of single degree of freedom systems were evaluated over 28 different earthquake situations. The energy spectra intended to be an alternative to the traditional acceleration spectra were created using the acceleration parameter equivalent to the input energy. Two new energy parameters, which take into account the effective duration of the earthquake, are proposed, and the relationship between the strength-oriented spectral acceleration parameters and the energy parameters used in the literature is examined by correlation study. According to the results obtained, it has been seen that energy oriented earthquake parameters, which give close values in similar period situations, will be a good alternative to strength oriented earthquake parameters. It was observed that the energy parameters were affected by the effective duration of the earthquake, unlike the strength-based parameters. It has been revealed that the newly proposed energy parameters considering the effective duration give good correlations. Finally, it was concluded that the energy parameters can be used in the design, and the newly proposed effective energy parameters can shorten the analysis durations.

• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.325-330
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• 2019

Band convergence is known to be effective in improving thermoelectric performance by increasing the Seebeck coefficient without significantly reducing electrical conductivity. Decoupling of the Seebeck coefficient and electrical conductivity in converged bands is the key requirement. Yet, the degree of decoupling depends on the band parameters of the converging bands. Herein, we report theoretical transport properties of two valence bands as their energy difference changes from 0.25 eV to 0 eV. In order to demonstrate the effect of band parameters in transport, we first conducted calculations for the case where the two bands have the same parameters. Then, we conducted the same calculation by doubling the density-of-states effective mass of one valence band. Given that there are two bands, each band's effective mass was doubled one at a time while the other band's effective mass remained constant. We found that the decoupling was strongest when the bands participating in convergence had the same band parameters.

• Structural Engineering and Mechanics
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• v.56 no.2
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• pp.257-273
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• 2015

Numerical value of correlation between effective parameters in the strength of a structure is as important as its stochastic properties in determining the safety of the structure. In this article investigation is made about the variation of coefficient of correlation between effective parameters in corrosion initiation time of reinforcement and the time of concrete cover cracking in reinforced concrete (RC) structures. Presence of many parameters and also error in measurement of these parameters results in uncertainty in determination of corrosion initiation and the time to crack initiation. In this paper, assuming diffusion process as chloride ingress mechanism in RC structures and considering random properties of effective parameters in this model, correlation between input parameters and predicted time to corrosion is calculated using the Monte Carlo (MC) random sampling. Results show the linear correlation between corrosion initiation time and effective input parameters increases with increasing uncertainty in the input parameters. Diffusion coefficient, concrete cover, surface chloride concentration and threshold chloride concentration have the highest correlation coefficient respectively. Also the uncertainty in the concrete cover has the greatest impact on the coefficient of correlation of corrosion initiation time and the time of crack initiation due to the corrosion phenomenon.

• Journal of Environmental Science International
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• v.2 no.3
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• pp.193-199
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• 1993

This study has two objectives. One is developing the runoff model for Hoe-Dong Reservoir basin located at the upstream of Su-Young River in Pusan. To develop the runoff model, basic hydrological parameters - curve number to find effective rainfall, and storage coefficient, etc. - should be estimated. In this study, the effective rainfall was calculated by the SCS method, and the storage coefficient used in the Clark watershed routing was cited from the report of P.E.B. The other is the derivation of transfer function for Hoe-Dong Reservoir basin. The linear, discrete, input-output model which contained six parameters was selected, and the parameters were estimated by the least square method and the correlation function method, respectively. Throughout this study, rainfall and flood discharge data were based on the field observation in 1981.8.22 - 8.23 (typhoon Gladys). It was observed that the Clark watershed routing regenerated the flood hydrograph of typhoon Gladys very well, and this fact showed that the estimated hydrological parameters were relatively correct. Also, the calculated hydrograph by the linear, discrete, input-output model showed good agreement with the regenerated hydrograph at Hoe-Dong Dam site, so this model can be applicable to other small urban areas. Key Words : runoff, effective rainfall, SCS method, clark watershed iou상ng, hydrological parameters, parameter estimation, least square method, correlation function method, input-output model, typhoon gladys.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1758-1771
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• 2017

In this study, to determine the most effective alloy for shielding against gamma-rays, the gamma-ray shielding parameters of six types of cerrobend alloys have been investigated. Gamma-ray interaction with the cerrobend alloys has been discussed mainly in terms of total mass attenuation coefficient (${\mu}_t$), half value layer (HVL), tenth value layer (TVL), effective atomic number ($Z_{eff}$), and effective electron density ($N_{eff}$). These parameters have been calculated by theoretical approach using the ParShield program in a photon energy range between 0.1 MeV and 100 GeV. The dependence of these parameters on the incident photon energy and chemical composition of the cerrobend alloys has been studied.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.35-39
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• 1998

Determination of effective EDM parameters is significant to increase productivity. However, With the complexity of EDM phenomena, a universal selection method of EDM parameters has not been established yet. Moreover, No attempt has been tried before to suggest a logical method in determining essential machining parameters for effective electrical discharge machining. Peak current, one of the most significant factors in EDM, is proportional to EDM area. This paper presents a method that can be Z-map modeling from CMM data, and calculate EDM area using Z-map.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.33-38
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• 2008

A ground-loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. The Size and performance of this heat exchanger is highly dependent on ground thermal properties. A proper design requires certain site-specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U-tube configurations on ground effective thermal conductivity. In this study, thermal response tests were conducted using a testing device with 9-different ground-loop heat exchangers. From the experimental results, the length of ground-loop heat exchanger affects to the effective thermal conductivity. Among the various grouting materials, the bentonite-based grout with silica sand shows the largest thermal conductivity value.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.811-816
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• 2022

This work presents the methodology used to expand the capabilities of the Monte Carlo code OpenMC for the calculation of reactor kinetic parameters: effective delayed neutron fraction β_eff and neutron generation time L. The modified code, OpenMC(Time-Dependent) or OpenMC(TD), was then used to calculate the effective delayed neutron fraction by using the prompt method, while the neutron generation time was estimated using the pulsed method, fitting Λ to the decay of the neutron population. OpenMC(TD) is intended to serve as an alternative for the estimation of kinetic parameters when licensed codes are not available. The results obtained are compared to experimental data and MCNP calculated values for 18 benchmark configurations.

• Computers and Concrete
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• v.9 no.1
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• pp.1-19
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• 2012

The size-effect study of various fracture parameters obtained from two parameter fracture model, effective crack model, double-K fracture model and double-G fracture model is presented in the paper. Fictitious crack model (FCM) for three-point bend test geometry for cracked concrete beam of laboratory size range 100-400 mm is developed and the different fracture parameters from size effect model, effective crack model, double-K fracture model and double-G fracture model are evaluated using the input data obtained from FCM. In addition, the fracture parameters of two parameter fracture model are obtained using the mathematical coefficients available in literature. From the study it is concluded that the fracture parameters obtained from various nonlinear fracture models including the double-K and double-G fracture models are influenced by the specimen size. These fracture parameters maintain some definite interrelationship depending upon the specimen size and relative size of initial notch length.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.963-969
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• 2008

The wear particles are relative to the failure and the life of machine elements directly. But it is not laid down to calculate shape parameters of wear particle. To analyze a variation of distributed characteristics of wear particles on moving conditions, its shape parameters such as diameter and roundness were calculated the quantitative values by digital image processing, and had to be defined the effective method of using those data. Up to the present, the shape parameters have been used simply into the average values. But these values are not effective to analyze a variation of distributed characteristics of occurred wear particles on moving conditions. In this study, the relative histograms of shape parameters of wear particles were used for the purpose of analyzing the distribution of wear particles in various conditions. The results showed that the relative histogram of shape parameters can be effectively represented to study a wear mechanism.