• Geomechanics and Engineering
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• 제4권3호
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• pp.173-190
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• 2012

With recent growing interests in the Performance-Based Seismic Design and Assessment Methodology, more realistic modeling of a structural system is deemed essential in analyzing, designing, and evaluating both newly constructed and existing buildings under seismic events. Consequently, a shallow foundation element becomes an essential constituent in the implementation of this seismic design and assessment methodology. In this paper, a contact interface fiber section element is presented for use in modeling soil-shallow foundation systems. The assumption of a rigid footing on a Winkler-based soil rests simply on the Euler-Bernoulli's hypothesis on sectional kinematics. Fiber section discretization is employed to represent the contact interface sectional response. The hyperbolic function provides an adequate means of representing the stress-deformation behavior of each soil fiber. The element is simple but efficient in representing salient features of the soil-shallow foundation system (sliding, settling, and rocking). Two experimental results from centrifuge-scale and full-scale cyclic loading tests on shallow foundations are used to illustrate the model characteristics and verify the accuracy of the model. Based on this comprehensive model validation, it is observed that the model performs quite satisfactorily. It resembles reasonably well the experimental results in terms of moment, shear, settlement, and rotation demands. The hysteretic behavior of moment-rotation responses and the rotation-settlement feature are also captured well by the model.

• Asian Pacific Journal of Cancer Prevention
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• 제17권12호
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• pp.5075-5080
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• 2016

Purpose: Factors associated with ever-use and differences between ever-users and non-users of tobacco among adolescent school students from low income families in Mumbai were assessed. Materials and Methods: A self-administered questionnaire, completed by 1918 students from grades 7, 8 and 9 in 12 schools managed by the city municipal corporation in July 2015, gathered data on socio-demographic characteristics, tobacco use and tobacco-related knowledge, attitudes and beliefs. Results: Although only 1% of respondents thought tobacco was cool, nearly 35% were unaware of associations between tobacco use and health problems. Male students were almost twice as likely (OR=2.5, P <= 0.05) to have ever used tobacco compared to females and Supari (areca nut) users were eight times more likely (OR=8.99, P < 0.001) than Supari non -users. Tobacco-users were more likely to agree with statements: 'People who use tobacco have more friends' (OR=2.8, P = 0.004), 'Smoking relieves stress' (OR=5.6, P = 0.002) and 'It is possible to purchase any tobacco product within 100 yards of school' (OR=10.8, P < 0.001). Conclusion: This study highlights the gains made by tobacco prevention campaigns in that almost all students did not consider tobacco as cool or a stress reliever. However, they still need education about health consequences of tobacco-use. In addition, Supari use has to be addressed in school-based tobacco prevention and cessation initiatives. Furthermore, programs must also address perceptions and norms related to peers and tobacco use and ensure active implementation of existing laws. Such integrated measures will help ensure tobacco-free spaces around schools.

• Interaction and multiscale mechanics
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• 제3권1호
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• pp.55-79
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• 2010

The effect of soil-structure interaction on a single-storey, two-bay space frame resting on a pile group embedded in the cohesive soil (clay) with flexible cap is examined in this paper. For this purpose, a more rational approach is resorted to using the finite element analysis with realistic assumptions. Initially, a 3-D FEA is carried out independently for the frame on the premise of fixed column bases in which members of the superstructure are discretized using the 20-node isoparametric continuum elements. Later, a model is worked out separately for the pile foundation, by using the beam elements, plate elements and spring elements to model the pile, pile cap and soil, respectively. The stiffness obtained for the foundation is used in the interaction analysis of the frame to quantify the effect of soil-structure interaction on the response of the superstructure. In the parametric study using the substructure approach (uncoupled analysis), the effects of pile spacing, pile configuration, and pile diameter of the pile group on the response of superstructure are evaluated. The responses of the superstructure considered include the displacement at top of the frame and moments in the columns. The effect of soil-structure interaction is found to be quite significant for the type of foundation considered in the study. Fair agreement is observed between the results obtained herein using the simplified models for the pile foundation and those existing in the literature based on a complete three dimensional analysis of the building frame - pile foundation - soil system.

• Geomechanics and Engineering
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• 제32권1호
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• pp.69-84
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• 2023

This paper proposes a novel frame element on Winkler-Pasternak foundation for analysis of a non-ductile reinforced concrete (RC) member resting on foundation. These structural members represent flexural-shear critical members, which are commonly found in existing buildings designed and constructed with the old seismic design standards (inadequately detailed transverse reinforcement). As a result, these structures always experience shear failure or flexure-shear failure under seismic loading. To predict the characteristics of these non-ductile structures, efficient numerical models are required. Therefore, the novel frame element on Winkler-Pasternak foundation with inclusion of the shear-flexure interaction effect is developed in this study. The proposed model is derived within the framework of a displacement-based formulation and fiber section model under Timoshenko beam theory. Uniaxial nonlinear material constitutive models are employed to represent the characteristics of non-ductile RC frame and the underlying foundation. The shear-flexure interaction effect is expressed within the shear constitutive model based on the UCSD shear-strength model as demonstrated in this paper. From several features of the presented model, the proposed model is simple but able to capture several salient characteristics of the non-ductile RC frame resting on foundation, such as failure behavior, soil-structure interaction, and shear-flexure interaction. This confirms through two numerical simulations.

• Structural Monitoring and Maintenance
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• 제7권1호
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• pp.43-58
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• 2020

Pile foundations of existing bridges lie in soil and water environment for long term and endure relatively heavy vertical loads, thus prone to damages, especially after stricken by external forces, such as earthquake, collision, soil heap load and etc., and the piles may be injured to certain degrees as well. There is a relatively complete technical system for quality inspection of new bridge pile foundations without structures on the top. However, there is no mature technical standard in the engineering community for the non-destructive testing technology specific to the existing bridge pile foundations. The quality of bridge pile foundations has always been a major problem that plagues bridge maintenance. On the basis of many years' experiences in test engineering and theoretical studies, this study developed a new type of detection technology and equipment for the existing bridge piles.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.11-12
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• 2013

It is required to response to the demand for new space due to high density of population and buildings in urban area. In particular, in case of big cities such as Seoul where the lack of new construction site due to the depletion of available space, existing buildings must be demolished for new construction. Utilization of urban underground space can be an alternative to solve for urban space problems. There are applications of underpinning methods using micropiles for existing buildings. Sometimes, the difficulties come from the compact space available for new foundation underneath the existing ones. In this paper, a novel underpinning method is introduced which can solve the space restriction problems underneath existing columns.

• 한국프랜차이즈경영연구
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• 제3권1호
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• pp.92-110
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• 2012

최근 경제적 불안과 실업율의 증가 등의 사회적인 문제로 인하여 창업시장의 수요가 증가 하는 가운데 청년창업 지원방안, 중기청 창업지원 계획 등의 정부의 창업 지원정책을 바탕으로 창업 시장은 지속적인 성장 추세를 보이고 있다. 이 같은 창업 시장의 확대에 힘입은 프랜차이즈 시장의 동반 상승이 예상되는 바, 프랜차이즈 시장에 대한 보다 현실적이고 구체적인 연구는 그 중요성이 점차 커질 것으로 사료된다. 본 연구에서는 가맹희망자의 브랜드 선택에 있어 기존에 선행연구를 개선하여 브랜드 선택에 영향을 미지는 선행 변수로 브랜드이미지, 본사의 지원, 창업비용, 정보탐색활동으로 보고 브랜드 선택에 영향을 미치는 요인을 규명하였으며, 그 결과는 다음과 같다. 첫째, 첫째, 창업업종 연령, 성별, 결혼여부에 따라 브랜드 이미지에 대한 생각 및 창업가능성에는 차이가 있다. 둘째, 예비창업자의 가맹계약의향에 있어 가장 중요한 요소는 경제적 특성이다. 브랜드 이미지 및 가맹지원, 정보탐색활동은 가맹희망자에게 있어 큰 영향을 미치는 속성으로 보기는 어려우며, 오히려 가맹점을 운영하는데 드는 비용(초기 창업비용 및 자기자본과의 일치성, 홍보비용, 운영자금, 시설/장비 재투자 등)이 중요한 속성인 것으로 나타났다. 특히 초기 창업비용과 자기자본과의 일치성은 가맹희망자에게 있어 가장 중요한 요인인 것으로 나타났다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.658-661
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• 2008

최근 세계적으로 유수한 인터넷 사이트들의 해킹으로 인해 네트워크 보안의 중요성이 강조되고 있다. 네트워크 보안을 위해 방화벽보다는 좀 더 신뢰성이 높은 네트워크 및 시스템에 대한 보안 솔루션으로 침입 탐지 시스템(Intrusion Detection System)이 차세대 보안 솔루션으로 부각되고 있다. 본 논문에서는 기존의 IDS의 단점이었던 호스트 레벨에서 확장된 분산환경에서의 실시간 침입 탐지는 물론 이기종간의 시스템에서도 탐지가 가능한 새로운 IDS 모델을 제안 설계하였다. 그리고, 프로토타입을 구현하여 그 타당성을 검증하였다. 이를 위해 서로 다른 이기종에서 분산 침입 탐지에 필요한 감사 파일을 자동적으로 추출하기 위해서 패턴 추출 에이전트를 이용하였다.

• Wind and Structures
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• 제21권6호
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• pp.597-607
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• 2015

With an increasing demand of a renewable energy, new offshore wind turbine farms are being planned in some parts of the world. Foundation installation asks a significant cost of the total budget of offshore wind turbine (OWT) projects. Hence, a cost reduction from foundation parts is a key element when a cost-efficient designing of OWT budget. Mono-piles have been largely used, accounting about 78% of existing OWT foundations, because they are considered as a most economical alternative with a relatively shallow-water, less than 30 m of seawater depth. OWT design standards such as IEC, GL, DNV, API, and Eurocode are being developed in a form of reliability based limit state design method. In this paper, reliability analysis using the response surface method (RSM) and numerical simulation technique for an OWT mono-pile foundation were performed to investigate the sensitivities of mono-pile design parameters, and to find practical implications of RSM reliability analysis.

• Geomechanics and Engineering
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• 제19권6호
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• pp.473-484
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• 2019

In this paper, the geotechnical report of the Northern Fereshteh area in Tabriz is used and the characteristics of shallow foundation of a single pile and compared pile group and geogrid in terms of the settlement of a building foundation on clayey soil. Additionally, impacts of existing variables such as the number of geogrid layers, the length of the pile, and the depth of groundwater level affected by the dynamic load caused by the Taiwan Jiji earthquake via numerical analysis using PLAXIS software are examined. The results of fifty-four models indicated that the construction of a pile group with a diameter of 1 meter and a length of 14 meters significantly diminished the consolidation settlement of the soil in the Northern Fereshteh area, where the settlement value has been triggered by the load inflicted by earthquake. Moreover, the construction of four layers of geogrid at intervals of one meter led to a significant decrease in the settlement. Finally, after reaching a maximum depth, it had no reducing effects on the foundation settlement.