• Kyungpook Mathematical Journal
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• 제50권2호
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• pp.255-266
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• 2010

We consider a delayed predator-prey system with Holling II functional response. Firstly, the paper considers the stability and local Hopf bifurcation for a delayed prey-predator model using the basic theorem on zeros of general transcendental function, which was established by Cook etc.. Secondly, special attention is paid to the global existence of periodic solutions bifurcating from Hopf bifurcations. By using a global Hopf bifurcation result due to Wu, we show that the local Hopf bifurcation implies the global Hopf bifurcation after the second critical value of delay. Finally, several numerical simulations supporting the theoretical analysis are given.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.452-457
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• 2008

In this paper, the vibrations of floor systems of which buildings are under construction are studied by experimental and analysis method. The first step is to measure the operational response data and FRF at the supporting points of the utility and the second step is to calculate the dynamic load by TPA Method which provided by LMS VirtualLab System Analysis Module. The dynamics we used to identify is expressed by below equation; $$\{F_{oper}\}=[H]^{-1}\;{\cdot}\;\{{.. \atop x_{oper}}\}$$ Where, H(Transfer function between position of the force and response) and x(response) are measured by vibration test.

• Earthquakes and Structures
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• 제14권1호
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• pp.85-94
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• 2018

The paper focuses on the seismic responses of a hyperbolic cooling tower resting on soil foundation represented by the three-parameter Vlasov elastic soil model. The three-parameter soil model eliminates the necessity of field testing to determine soil parameters such as reaction modulus and shear parameter. These parameters are calculated using an iterative procedure depending on the soil surface vertical deformation profile in the model. The soil and tower system are modeled in SAP2000 structural analysis program using a computing tool coded in MATLAB. The tool provides a two-way data transfer between SAP2000 and MATLAB with the help of Open Application Programming Interface (OAPI) feature of SAP2000. The response spectrum analyses of the tower system with circular V-shaped supporting columns and annular raft foundation on elastic soil are conducted thanks to the coded tool. The shell and column forces and displacements are presented for different soil conditions and fixed raft base condition to investigate the effects of soil-structure interaction. Numerical results indicate that the flexibility of soil foundation leads to an increase in displacements but a decrease in shell membrane and column forces. Therefore, it can be stated that the consideration of soil-structure interaction in the seismic response analysis of the cooling tower system provides an economical design process.

• Steel and Composite Structures
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• 제52권1호
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• pp.1-14
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• 2024

This paper introduces a system allows for seismic isolation of the pallet from the rack in the down-aisle direction, occupies minimal vertical space (5 cm) and ±7.5 cm of deformation range. A conceptual model of the isolation system is presented, leading to a constitutive equation governing its behavior. A first experimental campaign studying the response of the isolation system's components was conducted to calibrate the parameters of its constitutive equation. A second experimental campaign evaluated the response of the isolation system with mass placed on it, subjected to cyclic loading. The results of this second campaign were compared with the numerical predictions using the pre-calibrated constitutive equation, allowing a double-blind validation of the constitutive equation of the isolation system. Finally, a numerical evaluation of the isolation system subjected to a synthetic earthquake of one component. This evaluation allowed verifying attributes of the proposed isolation system, such as its self-centering capacity and its effectiveness in reducing the absolute acceleration of the isolated mass and the shear load transmitted to the supporting beams of the rack.

• Wind and Structures
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• 제22권6호
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• pp.617-633
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• 2016

In this paper, the analysis of hyperbolic cooling tower on elastic subsoil exposed to unsymmetrical wind loading is presented. Modified Vlasov foundation model is used to determine the soil parameters as a function of vertical deformation profile within subsoil. The iterative parameter updating procedure involves the use of Open Application Programming Interface (OAPI) feature of SAP2000 to provide two way data flow during execution. A computing tool coded in MATLAB employing OAPI is used to perform the analysis of hyperbolic cooling tower with supporting columns over a hollow annular raft founded on elastic subsoil. The analysis of such complex soil-structure system is investigated under self-weight and unsymmetrical wind load. The response of the cooling tower on elastic subsoil is compared with that of a tower that its supporting raft foundation is treated as fixed at the base. The results show that the effect of subsoil on the behavior of cooling tower is considerable at the top and bottom of the wall as well as supporting columns and raft foundation. The application of a full-size cooling tower has demonstrated that the procedure is simple, fast and can easily be implemented in practice.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.59-64
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• 2018

In recent years, the solar cell market has steadily grown with the demand for new energies. And wire sawing is one of the most critical processes in manufacturing solar cell wafer which is supposed to affect the breakage of wafers most during the process and afterwards. Generally, the defects of the wafers are generated from the structural vibrations of the machine. In the sawing process, the vibrations cause unnecessary normal stress on the cut surface of wafers, and eventually create the surface damage or leave the residual stress. In this study, the dynamic properties of a wire saw have been analyzed through the frequency response test and the computer simulation. And the effects of the design alterations have been investigated to stabilize the machine structure and further to reduce the vibrations. The result shows that relatively simple design alterations of supporting structure without any change of major parts of the machine can suppress the vibrations of the machine effectively.

• Geomechanics and Engineering
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• 제33권5호
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• pp.439-451
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• 2023

The construction of shield tunnelling in urban sites is facing serious risks from complex and changeable underground conditions. Construction problems in the sand-clay mixed ground have been more reported in recent decades for its poor control of soil loss in tunnel face, ground settlement and supporting pressure. Since the limitations of observation methods, the conventional physical modelling experiments normally simplify the tunnelling to a plane strain situation whose results are not reliable in mixed ground cases which exhibit more complicated responses. We propose a new method for the study of the mixed ground tunnel through which mixed lays are simulated with transparent soil surrogates exhibiting different mechanical properties. An experimental framework for the transparent soil modelling of the mixed ground tunnel was established incorporated with the self-developed digital image correlation system (PhotoInfor). To understand better the response of face stability, ground deformation, settlement and supporting phenomenon to tunnelling excavation in the sand-clay mixed ground, a series of case studies were carried out comparing the results from cases subjected to different buried depths and mixed phenomenon. The results indicate that the deformation mode, settlement and supporting phenomenon vary with the mixed phenomenon and buried depth. Moreover, a stratigraphic effect exists that the ground movement around mixed face reveals a notable difference.

• Structural Engineering and Mechanics
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• 제40권6호
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• pp.763-782
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• 2011

Results from nonlinear time-history analyses of wall-frame structural models indicate that the condition of vulnerable foundations -for which uplifting and reaching the bearing capacity of the supporting soil can occur before yielding at the base of the shear walls- may not be necessarily detrimental to the drift response of buildings under strong ground motions. Analyses also show that a soil-foundation system can inherently have deformation capacity well in excess of the demand and thus act as a source of energy dissipation that protects the structural integrity of the shear walls.

• 한국사회복지학
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• 제43권
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• pp.76-105
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• 2000

In the last two decades, the welfare states have undergone the changes of restructuring towards two ways. One is a restructuring of workfare and the other is a restructuring of the gender model of welfare state. In Korea, the workfare is reflecting on the DJ Welfarism 'Productive Welfare', but the gender model has a little effect on the public policies. By the way, It is imported that has the gender perspective in approaching the self-supporting program in the public assistance representing of the DJ Welfarism. Because almost 60% of the beneficiaries of the program are women. The Gender-mainstreaming strategy criticizes for the laws, the public policies, the public programs that considered gender-neutral or gender-blinded, and then complete the equality between women and men through the modification or development of those. The approach of Gender-mainstreaming is very important strategy for not only women who are self-reliance recipient but also successful settlement of self-supporting program. Nowadays that program is not execute yet. Then we hardly have information about recipients and the results that expected from that. At this point of gender-mainstreaming, this report suggest the strategy to development and settlement of the self-supporting program in the basics of analysis for the low-income unemployed and the government policy response to unemployment. For the gender models of the self-supporting program, the most important thing is throwing the male breadwinner model and adoption the dural-earner model (the gender model) about that program. Then we must produce gender-statistics data, develop programs for public work, job replacement, job training, evaluating system, etc. with gender perspective.

• 자원ㆍ환경경제연구
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• 제24권1호
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• pp.225-249
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• 2015

우리나라 전력시장에서도 보다 선진화된 요금체계가 도입되어야 한다는 관점에서 가정부문에서의 선택적 전력요금제 도입이 논의되고 있다. 본 연구에서는 고정요금제, 실시간 요금제(RTP), 계시별 요금제(TOU)를 도입하였을 때의 효과를 분석하기 위해 행위자기반모형을 구축하였다. 시간대별 전력소비 유형이 다른 행위자를 설정하였으며, 전력수요와 전력가격을 연동시키기 위해 발전부문도 모형에 도입하였다. 분석 결과, 소비자 유형이 피크부하 때 덜 사용하는 경우에는 실시간 요금제인 RTP나 TOU를 택했을 때의 비용절감 효과가 컸으며, 특히 스마트 계량기 등을 이용하여 전력사용 시간을 최적화할 수 있는 경우에는 그 편익이 더욱 증가한 것으로 나타나 향후 스마트 전력소비를 위한 인프라 구축이 필요함을 알 수 있다.