• 한국사회정책
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• v.24 no.2
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• pp.61-86
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• 2017

Along with the well-established evidence on the negative effect of social isolation on physical and mental health, increasing attention has been paid to multi-dimensional nature of social isolation. One line of study on social isolation has discussed different pathways between objective and subjective social isolation and health. Another stream of the research focused on the possibly non-linear association between social isolation and health by age cohort groups. Drawing from the two lines of research, this study aimed at empirically examine to what extent objective and subjective social isolation are associated with physical and mental health independently and how the associations vary by three age cohorts(i.e. the middle-aged, the young old, the old-old). Data came from the first wave of Korean Social Life, Health and Aging Project (KSHAP) (N= 814). Findings showed 1) objective subjective isolation were significantly related with worse physical and mental health, interestingly, subjective social isolation was associated with mental health only, 2) pattern of association between social isolation and physical health varied by age cohorts. Specifically, compared to the middle-aged, the young old with higher objective social isolation exhibited lower level of physical health, while the old-old with higher subjective social isolation were likely to experience lower physical health. Based on the findings, we discussed implications and suggestions for future research and relevant policy/program development for ameliorating objective and subjective social isolation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.157-165
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• 2011

Base isolation system is widely used for reduction of dynamic responses of structures subjected to seismic load. Recently, research on a smart base isolation system that can effectively reduce dynamic responses of the isolated structure without accompanying increases in base drifts has been actively conducted. In this study, a smart base isolation system was applied to an arch structure subjected to seismic excitation and its control performance for reduction of seismic responses was evaluated. In order to make a smart base isolation system, 4kN MR dampers and low damping elastomeric bearings were used. Seismic response control performance of the proposed smart base isolation system was compared to that of the optimally designed lead-rubber bearing(LRB) isolation system. To this end, an artificial ground motion developed based on KBC2009 design response spectrum was used as a seismic excitation. Fuzzy control algorithm was used to control MR damper in the smart base isolation system and multi-objective genetic algorithm was employed to optimize the fuzzy controller. Based on numerical simulation results, it has been shown that the smart base isolation system can drastically reduce base drifts and seismic responses of the example arch structure in comparison with LRB isolation system.

• Journal of Korean Association for Spatial Structures
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• v.19 no.3
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• pp.51-59
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• 2019

A hybrid mid-story seismic isolation system with a smart damper has been proposed to mitigate seismic responses of tall buildings. Based on previous research, a hybrid mid-story seismic isolation system can provide effective control performance for reduction of seismic responses of tall buildings. Structural design of the hybrid mid-story seismic isolation system is generally performed after completion of structural design of a building structure. This design concept is called as an iterative design which is a general design process for structures and control devices. In the iterative design process, optimal design solution for the structure and control system is changed at each design stage. To solve this problem, the integrated optimal design method for the hybrid mid-story seismic isolation system and building structure was proposed in this study. An existing building with mid-story isolation system, i.e. Shiodome Sumitomo Building, was selected as an example structure for more realistic study. The hybrid mid-story isolation system in this study was composed of MR (magnetorheological) dampers. The stiffnessess and damping coefficients of the example building, maximum capacity of MR damper, and stiffness of isolation bearing were simultaneously optimized. Multi-objective genetic optimization method was employed for the simultaneous optimization of the example structure and the mid-story seismic isolation system. The optimization results show that the simultaneous optimization method can provide better control performance than the passive mid-story isolation system with reduction of structural materials.

• Structural Engineering and Mechanics
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• v.81 no.6
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• pp.691-703
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• 2022

To obtain the seismic response of lead-cored rubber, shape memory alloy (SMA)-rubber isolation Plate-shell Integrated Concrete Liquid-Storage Structure (PSICLSS), based on a PSICLSS in a water treatment plant, built a scale experimental model, and a shaking table test was conducted. Discussed the seismic responses of rubber isolation, SMA-rubber isolation PSICLSS. Combined with numerical model analysis, the vibration characteristics of rubber isolation PSICLSS are studied. The results showed that the acceleration, liquid sloshing height, hydrodynamic pressure of rubber and SMA-rubber isolation PSICLSS are amplified when the frequency of seismic excitation is close to the main frequency of the isolation PSICLSS. The earthquake causes a significant leakage of liquid, at the same time, the external liquid sloshing height is significantly higher than internal liquid sloshing height. Numerical analysis showed that the low-frequency acceleration excitation causes a more significant dynamic response of PSICLSS. The sinusoidal excitation with first-order sloshing frequency of internal liquid causes a more significant sloshing height of the internal liquid, but has little effect on the structural principal stresses. The sinusoidal excitation with first-order sloshing frequency of external liquid causes the most enormous structural principal stress, and a more significant external liquid sloshing height. In particular, the principal stress of PSICLSSS with long isolation period will be significantly enlarged. Therefore, the stiffness of the isolation layer should be properly adjusted in the design of rubber and SMA-rubber isolation PSICLSS.

• Korean Journal of Veterinary Service
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• v.14 no.1
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• pp.41-48
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• 1991

Bordetella bronchiseptica were isolated from nasal swabs of the pigs being raised in Eastern Gyeong Nam area from September to December, 1990. Servey on isolation frequency, antimicrobial susceptibility and serum agglutination antibody titer were carried out. The results obtained were summarized as follows : 1. Isolation of B. bronchiseptica were 47 pigs in 113, shown 41.6% of isolation rate and isolation rate were higher in non-vaccination group(60.0%) than vaccination group(28.8%), 2. Isolation rate by ages were the lowest below 1 week ages(22.2%), the highest in 78 weeks ages(55.6 %) and sows was shown 39.3%. 3. It was also found that 47 strains of B. bronchiseptica isolated were highly susceptibility to minocyclin, gentamicin, neomycin, colistin and kanamycin, and highly resistant to penicillin, linsmycin, bacitracin, sulphonamides and chloramphenicol. 4. Isolation rate by the difference of seum agglutination antibody titer were more high at low agglutination titer than high agglutination titer.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.7 s.124
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• pp.565-571
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• 2007

In the process of accurate manufacture and measurement, it is necessarily required to isolate external or internal vibration due to external disturbance and internal actuators. The higher vibration isolation system gets damping around resonance, the better it is generally. This paper analyzes the performance of an existing passive air-spring for vibration isolation table by using experiment and simulation. Optimal design for a passive air spring can be obtained by tuning the size of the orifice. Also design for an active isolation system is carried out by applying PID controller and considering non-linearity of pneumatic characteristics with help of look-up table. We have developed the active vibration isolation table with the better isolation performance.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.120-127
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• 2001

Long term earthquake observations at different tunnel sites within a variety of alluvial soil deposits have demonstrated that a circular tunnel is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately. Based on this knowledge, the soil-tunnel interaction and isolation effect for this particular vibration mode is investigated. Interaction effect is considered with the condition of fixed tangential strain between the tunnel and the soil. Isolation effect embodied by covering up the tunnel with isolation materials is discussed as a possible measure for mitigating seismic damage to it. When Poisson`s ratio of isolation material decreases or the shear modulus ratios of the soil to isolation material become large, the isolation effect becomes bigger.

• Smart Structures and Systems
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• v.17 no.5
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• pp.709-724
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• 2016

This study investigates the optimum design parameters of a superelastic friction base isolator (S-FBI) system through a multi-objective genetic algorithm to improve the performance of isolated buildings against near-fault earthquakes. The S-FBI system consists of a flat steel-PTFE sliding bearing and superelastic NiTi shape memory alloy (SMA) cables. Sliding bearing limits the transfer of shear across the isolation interface and provides damping from sliding friction. SMA cables provide restoring force capability to the isolation system together with additional damping characteristics. A three-story building is modeled with S-FBI isolation system. Multiple-objective numerical optimization that simultaneously minimizes isolation-level displacements and superstructure response is carried out with a genetic algorithm in order to optimize S-FBI system. Nonlinear time history analyses of the building with optimal S-FBI system are performed. A set of 20 near-fault ground motion records are used in numerical simulations. Results show that S-FBI system successfully control response of the buildings against near-fault earthquakes without sacrificing in isolation efficacy and producing large isolation-level deformations.

• Journal of Korean Association for Spatial Structures
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• v.20 no.3
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• pp.99-106
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• 2020

If an excessive displacement occurs in the base isolation system, the structure will be damaged due to overturning of the upper structure. In this study, we analyze the behavior of base isolation by applying earthquake to base isolation with anti-uplift device. In the case of structures that generate horizontal reaction forces such as arch structures, horizontal reaction forces must be considered in the design of the base isolation and structural members. And anti-uplift device for preventing the excessive displacement of the base isolation system is needed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.437-444
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• 2006

Recently, as large structures become lighter and more flexible, the necessity of structural control for reducing excessive displacement and acceleration due to seismic excitation is increased. As a means to minimize seismic damages, various base isolation systems are adopted or considered for adoption. In this study, a base isolation system using Magneto-Sensitive(MS) rubbers is proposed and shown to effectively protect structures against earthquakes. The MS Rubber is a class of smart controllable materials whose mechanical properties change instantly by the application of a magnetic field To demonstrate the advantages of this approach, the MS Rubber isolation system is compared to Lead-Rubber Bearing(LRB) isolation systems and judged based on computed responses to several historical earthquakes. The MS Rubber isolation system is shown to achieve notable decreases in base drifts over comparable passive systems with no accompanying increase in base shears or in accelerations imparted to the superstructure.