• Geomechanics and Engineering
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• 제35권4호
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• pp.449-464
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• 2023

Advanced nonlinear effective stress constitutive models are started to be frequently used in one-dimensional (1D) and two-dimensional (2D) site response analysis for assessment of porewater generation and liquefaction potential in soft soil deposits. The emphasis of this research is on the assessment of the implementation of this category of models at the element stage. Initially, the performance of a coupled porewater pressure (PWP) and constitutive models were evaluated employing a catalogue of 40 unidirectional cyclic simple shear tests with a variety of relative densities between 35% and 80% and effective vertical stresses between 40 and 80 kPa. The authors evaluated three coupled constitutive models (PDMY02, PM4SAND and PDMY03) using cyclic direct simple shear tests and for decide input parameters used in the model, procedures are recommended. The ability of the coupled model to capture dilation as strength is valuable because the studied models reasonably capture the cyclic performance noted in the experiments and should be utilized to conduct effective stress-based 1D and 2D site response analysis. Sandy soils may become softer and liquefy during earthquakes as a result of pore-water pressure (PWP) development, which may have an impact on seismic design and site response. The tested constitutive models are mathematically coupled with a cyclic strain-based PWP generation model and can capture small-strain stiffness and large-strain shear strength. Results show that there are minor discrepancies between measured and computed excess PWP ratios, indicating that the tested constitutive models provide reasonable estimations of PWP increase during cyclic shear (r_u) and the banana shape is reproduced in a proper way indicating that dilation and shear- strain behavior is well captured by the models.

• 한국지반공학회논문집
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• 제36권6호
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• pp.17-34
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• 2020

일반적으로 잔교식 구조물의 내진설계를 위한 응답스펙트럼 해석 시 기준서들에서는 지진응답해석을 통해 증폭된 가속도를 입력가속도 활용하도록 제시하고 있으나, 기준서에 따라 방법이 상이하여 설계 시 혼란을 야기할 수 있다. 이에, 본 연구에서는 동적원심모형실험을 통해 지반 내 다양한 깊이에서 지반 가속도를 산정하였으며, 산정된 지반가 속도를 활용하여 응답스펙트럼 해석을 수행하였다. 이후 실험 및 해석을 통해 도출된 잔교식 안벽 구조물의 모멘트 결과를 비교하였으며, 응답스펙트럼 해석 시 적절한 입력지반가속도를 결정하기 위한 방법을 제시하고자 하였다. 실험 및 해석을 비교한 결과, 탄성 지반 스프링을 적용하는 경우 구조물의 고유주기를 가장 적절하게 모사하는 것으로 나타났으며, 상부 지표면에서 증폭된 지진파를 입력가속도로 활용하는 것이 사질토 지반에 관입된 구조물 응답을 가장 합리적으로 모사하는 것으로 나타났다.

• KIEAE Journal
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• 제10권1호
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• pp.45-55
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• 2010

While Korean construction companies are adapting themselves to rapidly changing business landscape at home and abroad, intensifying competition among competitors in local as well as global market deteriorates the profitability of construction industry, which leads to another problem. In response to such challenges, many construction companies continue to innovate their business portfolio and organization structure, with strong commitment to business process innovation. Furthermore, they need to analyze the productivity of project site management manpower overhauling business processes systematically and develop effective alternative strategies. This research aims to analyze the productivity of project site management manpower. Current operational practices of construction site organizations have been analyzed with focus on large construction companies in Korea and data gathered from project sites have been analyzed from a wide range of perspectives, In so doing, this research is expected to provide basic inputs for any subsequent attempt to estimate proper resource requirement for site management tasks in construction projects and analyze the management productivity of such resources by enabling construction companies to better understand the current operational status of site organization.

• Structural Engineering and Mechanics
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• 제36권1호
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• pp.111-127
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• 2010

This paper studies the effects of spatially varying ground motions on the responses of a bridge frame located on a canyon site. Compared to the spatial ground motions on a uniform flat site, which is the usual assumptions in the analysis of spatial ground motion variation effects on structures, the spatial ground motions at different locations on surface of a canyon site have different intensities owing to local site amplifications, besides the loss of coherency and phase difference. In the proposed approach, the spatial ground motions are modelled in two steps. Firstly, the base rock motions are assumed to have the same intensity and are modelled with a filtered Tajimi-Kanai power spectral density function and an empirical spatial ground motion coherency loss function. Then, power spectral density function of ground motion on surface of the canyon site is derived by considering the site amplification effect based on the one dimensional seismic wave propagation theory. Dynamic, quasi-static and total responses of the model structure to various cases of spatially varying ground motions are estimated. For comparison, responses to uniform ground motion, to spatial ground motions without considering local site effects, to spatial ground motions without considering coherency loss or phase shift are also calculated. Discussions on the ground motion spatial variation and local soil site amplification effects on structural responses are made. In particular, the effects of neglecting the site amplifications in the analysis as adopted in most studies of spatial ground motion effect on structural responses are highlighted.

• 대한전기학회논문지:전력기술부문A
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• 제48권5호
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• pp.494-501
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• 1999

In this research, ANN modeling method of SMES unit is developed for stability analysis, and the optimal site is selected to maximize stabilization effect of SMES unit. The ANN is trained by learning data which is obtained through the application of complex test function into the traditional mathematical mode. In order to verify the validity of proposed modeling method, fault data of sample power system is applied to both the traditional and the ANN models. When the response of traditional and proposed models are compared, the average error for the active and reactive power are 2.51[%], and 0.24[%], respectively. From the comparison, the relevance of proposed method is validated. For the transient stability analysis, an application method of the proposed model is presented, and the transient stability performance index, which describes system stabilization effect of SMES at disturbance, is also suggested, and optimal site selection method of SMES is presented. In the viewpoint of the voltage stability, system stabilization criterion of local bus is presented from P­V curve, and then optimal site which can maximize the voltage stabilization of the whole power system, is decided from the proposed voltage stability performance index.

• Geomechanics and Engineering
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• 제11권6호
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• pp.821-845
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• 2016

Extensive researches on distribution of earthquake induced damages in different regions have shown that geological and geotechnical conditions of the local soils significantly influence behavior of alluvial areas under seismic loading. In this article, the site of Babol city which is formed up of saturated fine alluvial soils is considered as a case study. In order to reduce the uncertainties associated with earthquake resistant design of structures in this area (Babol city), the required design parameters have been evaluated with consideration of site's dynamic effects. The utilized methodology combines experimental ground ambient noise analysis, expressed in terms of horizontal to vertical (H/V) spectral ratio, with numerical one-dimensional response analysis of soil columns using DEEPSOIL software. The H/V spectral analysis was performed at 60 points, experimentally, for the region in order to estimate both the fundamental period and its corresponding amplification for the ground vibration. The investigation resulted in amplification ratios that were greater than one in all areas. A good agreement between the proposed ranges of natural periods and alluvial amplification ratios obtained through the analytical model and the experimental microtremor studies verifies the analytical model to provide a good engineering reflection of the subterraneous alluviums.

• 농업과학연구
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• 제42권3호
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• pp.277-283
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• 2015

This study aims at analyzing determinants of non-farming income activities of female farmers, and presenting how to support their participation in non-farming activities. The result of logistic regressive analysis whose subjects are female farmers in the Chungnam area indicates that human and economic capital variables that can predict non-farming income activity participation statistically significantly are persons at the age of 40s to 50s and female farmers who returned to the rural areas. Farming characteristic variables are households that receive subsidiary and participate in two different types of farming whose main farming is rice. The female farmers who spend longer hours doing household chores participate in non-farming income activities more actively. In terms of policy and on-site response variables, the interest in farming and farming businesses shows positive relation, and that of farming and community organization participation presents negative relation. These analysis results indicate that the local government must present the policy that can select non-farming income activity participation groups strategically. This study suggest that it is necessary to expand community centered-non-farming income activities, and to expand or make laws to support female farmer's participation in non-farming activities.

• 한국소음진동공학회논문집
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• 제16권1호
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• pp.19-26
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• 2006

The test blasts were carried out by detonating some single blastholes at two upper sites of the underground storage cavern for the crude oil. One was performed at the entrance site of the construction tunnel and the other at the middle area of the underground storage cavern. Based on the blast-induced nitration measured by the test blasts, we suggested the propagation equations of blasting vibration that were capable of estimating the peak particle velocity. In addition, in order to assess the stability of the adjacent ground storage tank, we did the frequency analysis and the response spectrum analysis with the particle velocity-time history and the particle acceleration-time history that were measured by the test blast carried out on the entrance site of the construction tunnel. In result, it was predicted that the displacement on the highest part of the tank shell was less than the allowable displacement.

• Earthquakes and Structures
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• 제8권3호
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• pp.681-697
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• 2015

Iran as one of the countries located on the Alpine-Himalayan seismic belt has recently experienced a few number of catastrophic earthquakes. A well-known index of how buildings are affected by earthquakes is through assessment of probable Peak Ground Acceleration (PGA) and structures' response spectra. In this research, active faults around Kerman and Birjand, two major cities in eastern parts of Iran, have been considered. Seismic catalogues are gathered to categorize effects of surrounding faults on seismicity of the region. These catalogues were further refined with respect to time and space based on Knopoff-Gardner algorithm in order to increase statistical independency of events. Probabilistic Seismic Hazard Analysis (PSHA) has been estimated for each of cities regarding 50, 100, 200 and 500 years of structures' effective life-span. These results subsequently have been compared with Deterministic Seismic Hazard Analysis (DSHA). It has been observed that DSHA not necessarily suggests upper bound of PSHA results. Furthermore, based on spectral Ground Motion Prediction Equations (GMPEs), Uniform Hazard Spectra (UHS) and spectral acceleration were provided for 2% and 10% levels of probability of exceedance. The results show that increasing source-to-site distance leads to spectral acceleration reduction regarding each fault. In addition, the spectral acceleration rate of variation would increase if the source-to-site distance decreases.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.479-484
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• 2005

The test blasts were carried out by detonating some single blastholes at two upper sites of the underground storage cavern the crude oil. One was performed at the entrance site of the construction tunnel and the other at the middle part of the underground storage cavern. Based on the blast-induced vibration measured by the test blasts, we suggested the propagation equations of blasting vibration that were capable of estimating the peak particle velocity. In addition, in order to assess the stability of the nearest ground storage tank, we did the frequency analysis and the response spectrum analysis with the particle velocity-time history and the particle acceleration-time history that were measured by the test blast carried out on the entrance site of the construction tunnel. In result, it was predicted that the displacement on the highest part of the tank shell was less than the allowable displacement.