• 한국공간구조학회논문집
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• 제18권1호
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• pp.109-116
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• 2018

As the number of high-rise buildings increases, a mid-story isolation system has been proposed for high-rise buildings. Due to structural problems, an appropriate isolation layer displacement is required for an isolation system. In this study, the mid-story isolation system was designed and the seismic response of the structure was investigated by varying the yield strength and the horizontal stiffness of the seismic isolation system. To do this, a model with an isolation layer at the bottom of $15^{th}$ floor of a 20-story building was used as an example structure. Kobe(1995) and Nihonkai-Chubu(1983) earthquake are used as earthquake excitations. The yield strength and the horizontal stiffness of the seismic isolation system were varied to determine the seismic displacement and the story drift ratio of the structure. Based on the analytical results, as the yield strength and horizontal stiffness increase, the displacement of the isolation layer decreases. The story drift ratio decreases and then increases. The displacement of the isolation layer and the story drift ratio are inversely proportional. Increasing the displacement of the isolation layer to reduce the story drift ratio can cause the structure to become unstable. Therefore, an engineer should choose the appropriate yield strength and horizontal stiffness in consideration of the safety and efficiency of the structure when a mid-story isolation system for a high-rise building is designed.

• 대한미생물학회지
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• 제22권4호
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• pp.453-462
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• 1987

A total of 3,879 cases of feces and rectal swab from patient was collected in H. hospital from January 1974 to December 1986 in Seoul. Among the materials, the number of cases of Shigella spp. isolated were 197 strains of 139 patients. Infectous pattern and antibiotic sensitivity of Shigella spp. were as follows; The range of percentage of an identified Shigella spp. among total feces and rectal swabs was $1.5{\sim}12.5%$ yearly. The isolation ratios of Shigella spp. per each patient 1.35 for male and 1.19 for female. The isolation ratio of male to female was 1.28:1 in whole group. The isolated Shigella species was 81.0% in S. flexneri, 1.1% in S. boydii and 17% in S. sonnei. The highest number of Shigella spp. was found in August and September according to monthly isolation, on the other hand the lowest number of Shigella spp. was obserbed in March. The seasonal isolation rate of Shigella spp. was 31.7% in Fall, 27.3% in Summer, 21.6% in Winter and 19.3% in Spring. The age specific frequency of Shigellosis was 46.8% in $0{\sim}9$ year group, 8.6% in $10{\sim}19$, 7.2% in $40{\sim}49$ and 6.5% in $50{\sim}59$. The antibiotics showing over 80% susceptibility against Shigella spp. were gentamicin, kanamycin, amikacin, tobramycin, cefoperazone, cefoxitin, cefamandole nafate, cefotaxine and sisomycin.

• Earthquakes and Structures
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• 제4권4호
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• pp.341-363
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• 2013

Earthquake response calculation, parametric analysis and seismic parameter optimization of base-isolated structures are some critical issues for seismic design of base-isolated structures. To calculate the earthquake responses for such non-symmetric and non-classical damping linear systems and to implement the earthquake resistant design codes, a modified complex mode superposition design response spectrum method is put forward. Furthermore, to do parameter optimization for base-isolation structures, a graphical approach is proposed by analyzing the relationship between the base shear ratio of a seismic base-isolation floor to non-seismic base-isolation one and frequency ratio-damping ratio, as well as the relationship between the seismic base-isolation floor displacement and frequency ratio-damping ratio. In addition, the influences of mode number and site classification on the seismic base-isolation structure and corresponding optimum parameters are investigated. It is demonstrated that the modified complex mode superposition design response spectrum method is more precise and more convenient to engineering applications for utilizing the damping reduction factors and the design response spectrum, and the proposed graphical approach for parameter optimization of seismic base-isolation structures is compendious and feasible.

• Earthquakes and Structures
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• 제10권2호
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• pp.293-311
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• 2016

A parametric study on the nonlinear seismic response of isolated reinforced concrete structural frame is presented. Three prototype frames designed according to the 1954 Hellenic seismic code, with number of floor ranging from 1 to 3 were considered. These low rise frames are representative of many existing reinforced concrete buildings in Greece. The efficacy of the implementation of both lead rubber bearings (LRB) and friction pendulum isolators (FPI) base isolation systems were examined. The selection of the isolation devices was made according to the ratio $T_{is}/T_{fb}$, where Tis is the period of the base isolation system and $T_{bf}$ is the period of the fixed-base building. The main purpose of this comprehensive study is to investigate the effect of the isolation system period on the seismic response of inadequately designed low rise buildings. Thus, the implementation of isolation systems which correspond to the ratio $T_{is}/T_{fb}$ that values from 3 to 5 is studied. Nonlinear time history analyses were performed to investigate the response of the isolated structures using a set of three natural seismic ground motions. The evaluation of each retrofitting case was made in terms of storey drift and storey shear force while in view of serviceability it was made in terms of storey acceleration. Finally, the maximum developed displacements and the residual displacements of the isolation systems are presented.

• Genomics & Informatics
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• 제21권2호
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• pp.27.1-27.7
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• 2023

Recombination events complicate the evolutionary history of populations and species and have a significant impact on the inference of isolation-with-migration (IM) models. However, several existing methods have been developed, assuming no recombination within a locus and free recombination between loci. In this study, we investigated the effect of recombination on the estimation of IM models using genomic data. We conducted a simulation study to evaluate the consistency of the parameter estimators with up to 1,000 loci and analyze true gene trees to examine the sources of errors in estimating the IM model parameters. The results showed that the presence of recombination led to biased estimates of the IM model parameters, with population sizes being more overestimated and migration rates being more underestimated as the number of loci increased. The magnitude of the biases tended to increase with the recombination rates when using 100 or more loci. On the other hand, the estimation of splitting times remained consistent as the number of loci increased. In the absence of recombination, the estimators of the IM model parameters remained consistent.

• Journal of Mechanical Science and Technology
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• 제14권6호
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• pp.583-589
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• 2000

This paper presents a novel fault isolation filter design method using left eigenstructure assignment scheme proposed by the first author et al. The proposed method shows good performance of fault isolation with an exact eigenstructure assignment and guarantees that the corrupted ${\gamma}$ faults can be isolated simultaneously when the number of available output measurements are equal to or larger than (${\gamma}+1$). A numerical example for the fault isolation filter is also included.

• Earthquakes and Structures
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• 제1권2호
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• pp.215-230
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• 2010

The main objectives of this work were to investigate the effects of the nonlinear behavior of the isolation pads on the seismic response of bridges with rubber bearings, and to identify when base isolation improved their seismic performance. To achieve these objectives a parametric study was conducted designing a set of bridges for three different soil types and varying the number of spans, span lengths, and pier heights. The seismic responses (accelerations, displacements and pier seismic forces) were evaluated for three different structural models subjected to three earthquakes with different dynamic characteristics. The first represented bridges without base isolation; the second corresponded to the same bridges including now rubber bearings as an isolation system, with linear elastic behavior that shifted the natural period of the bridge by a factor of 2 to 4. In the third model the seismic response of bridges supported on lead-Rubber bearings was studied accounting for the nonlinear behavior of the lead. The results show clearly the importance of the nonlinear behavior on the seismic performance of the bridges.

• Journal of Microbiology and Biotechnology
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• 제28권1호
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• pp.77-86
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• 2018

The human pathogen and food spoiler Bacillus cereus can form biofilms that act as a persistent source of contamination, which is of public health concern. This study aimed to understand how the source of isolation might affect the behavior of biofilm formation. Biofilm formation abilities of 56 strains of B. cereus isolated from different environments, including human food poisoning, farm, and food, were determined. Crystal violet assay results revealed significant (p < 0.05) differences in biofilm formation abilities among the strains isolated from different sources only at an early stage of incubation. However, strain origin showed no impact on later stage of biofilm formation. Next, correlation of the group of isolates on the basis of their biofilm-forming abilities with the number of sessile cells, sporulation, and extracellular polymeric substance (EPS) formation was determined. The number of sessile cells and spores in biofilms was greatly influenced by the groups of isolates that formed dense, moderate, and weak biofilms. The contribution of extracellular DNA and/or proteins to EPS formation was also positively correlated with biofilm formation abilities. Our results that the source of isolation had significant impact on biofilm formation might provide important information to develop strategies to control B. cereus biofilm formation.

• 한국콘텐츠학회논문지
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• 제5권6호
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• pp.129-137
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• 2005

저궤도 위성통신시스템의 성능분석은 다양한 요소로 다양하게 시도되고 있다. 본 논문은 저궤도 위성통신시스템의 이전까지 연구에 없었던 사용자 밀집도를 고려한 셀 내 단말기 분포에 따른 간섭의 변화를 살펴보고, 단말기 분포 평균 거리에 따른 최대 사용자 수를 살펴보았다. 또한 저궤도 이동 통신시스템에 사용하는 안테나 종류(tapered-apertured antenna gaussian antenna)의 스폿 빔 isolation값에 따른 간섭을 살펴보았다. 이러한 간섭을 저궤도 위성 통신 시스템의 채널용량에 대입하여, 중요한 파라미터(대역폭, 캐리어 수)를 가지고 성능분석을 하였다. tapered-apertured antenna와 gaussian antenna를 비교함으로써, 어느 안테나가 간섭에 더 효과적이고 최적인지 알아보고자 한다.

• 제어로봇시스템학회논문지
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• 제7권5호
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• pp.384-392
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• 2001

In this paper, we propose a novel robust fault isolation filter design method using the left eigenstructure assignment scheme proposed by the authors. The proposed method guarantees that the ${\gamma}$ simultaneous faults can be isolated when the number of available outpur measurements is ${\gamma}$. Moreover, if there exist redundant output measurements, the eigenvaluses of te filter system can be assigned to the desired position or the filter can be designed robustly to, the system parameter variation. Liu & Si developed a filter design method which has the same purpose, fault isolation. However their method cannot use the redundant freedom of the output matrix C. The proposed filter can use the redundant freedom of the matrix C effectively. Beside this in this paper, an eigenstructure assignment methodology that satisfies the required fault isolation conditions is also proposed. The proposed fault isolation filter was applied for isolating the simultaneous faults to a VTOL aircraft in order to verify the fault isolation performance.