• Earthquakes and Structures
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• 제13권2호
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• pp.103-118
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• 2017

In vertical seismic isolation (VSI), a building is partitioned intentionally by vertical layers into two dynamically different substructures for seismic response reduction. Initially, a 1-story frame was partitioned into two substructures, interconnected by viscous and visco-elastic links, and seismic responses of the original and the vertically isolated structures (VIS) were obtained, considering a large number of stiffness and mass ratios of substructures with respect to the original structure. Color contour graphs were defined for presentation and investigation of large amounts of output results. Dynamic characteristics of the isolated structures were studied by considering the non-classical damping of the system, and then the effects of viscous and visco-elastic link parameters on the modal damping ratios were discussed. On this basis, three states of mass isolation, interactional state, and control mass were differentiated. Response history analyses were performed by Runge-Kutta numerical method. In these analyses, interaction of isolation ratios and link parameters, on response control of VIS was studied and the appropriate ranges for link parameters as well as the optimal ranges for isolation ratios were suggested. Results show that by using the VSI technique, seismic response reduction up to 50% in flexible substructure and even more in stiff substructure is achievable.

• 토지주택연구
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• 제4권2호
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• pp.185-192
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• 2013

이 논문에서는 저층 경량건물을 대상으로 고성능 내진을 구현하기 위하여 적용된 복합면진시스템의 적용효과가 비선형해석과 현장실험을 통하여 제시되었다. 이 연구에서 적용된 복합면진시스템은 슬라이딩베어링(sliding bearing)과 적층고무베어링(laminated rubber bearing)을 혼용하는 방법으로 전체 면진시스템의 고유주기를 신장시키는데 있어서 적층고무베어링이 지니는 한계를 극복하기 위한 것이다. 비선형해석결과, 복합면진시스템을 채용하여 설계된 면진건물은 아주 드물게 발생하는 강진에 대해서도 최대응답변위가 허용설계변위 이내이며, 최대응답전단력이 설계지진력 이하이므로 안전하게 유지될 수 있음을 알 수 있었다. 또한 현장실험결과, 면진층의 강성은 설계 등가강성 값의 약 95.8%에 해당하는 값을 나타내 전체 면진시스템의 실제 특성이 설계값과 잘 일치하고 있음을 확인할 수 있었다.

• Structural Engineering and Mechanics
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• 제75권1호
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• pp.33-47
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• 2020

In this paper the dynamic behavior of an isolated building subjected to idealized near-fault pulses is investigated. The building is represented with a simple 2-DOF model. Both linear and non-linear behavior of the isolation system is considered. Using dimensional analysis, in conjunction with closed form mathematical idealized pulses, appropriate dimensionless parameters are defined and self-similar curves are plotted on dimensionless graphs, based on which various conclusions are reached. In the linear case, the role of viscous damping is examined in detail and the existence of an optimum value of damping along with its significant variation with the number of half-cycles is shown. In the nonlinear case, where the behavior of the building depends on the amplitude of the excitation, the benefits of dimensional analysis are evident since the influence of the dimensionless 𝚷-terms is easily examined. Special consideration is given to the normalized strength of the non-linear isolation system that appears to play a complex role which greatly affects the response of the 2-DOF. In the last part of the paper, a comparison of the responses to idealized pulses between a linear fixed-base SDOF and the respective isolated 2-DOF with both linear and non-linear damping is conducted and it is shown that, under certain values of the superstructure and isolation system characteristics, the use of an isolation system can amplify both the normalized acceleration and displacement of the superstructure.

• Journal of Plant Biotechnology
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• 제36권3호
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• pp.261-267
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• 2009

The coexistence policy of GM and non-GM crops is still on the debates in EU since “the recommendation on guidelines for the development of national strategies and best practices to ensure the coexistence of GM crops with conventional and organic farming” has been reported in 2003. The major issues are maximum tolerance level of GMO admixture and minimum isolation distances of GM fields with others including conventional, organic and seeds production. Majority of member states in EU proposed that the tolerance level of GMO admixture must be more strictly controlled, in particular in the fields for organic crops and seeds production. To this end, it was proposed that minimum isolation distances to segregate GM crops from fields with organic crops and seeds production need to be further extended than those of conventional crops since cross pollination with other crops adjacent GM fields is known as the most prevalent source for GMO contamination. In these circumstances, it is strongly suggested that the current legislations need to be revised including the minimum isolation distances of fields for each species before field cultivation for a commercial GM crop is approved for the first time in South Korea.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.93-100
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• 2003

Seismic isolation systems can improve the seismic safety of nuclear power plants by decreasing seismic force transmitted to structures and equipment. This study evaluates the effectiveness of equipment seismic isolation systems by the comparison of core damage frequencies in non-isolated and isolated cases. It can be found that the seismic isolation systems increase seismic capacity of nuclear equipment and decrease core damage frequencies significantly. The effect of equipment isolation is more significant in the PGA range of 0.3g to 0.5g.

• 한국구조물진단유지관리공학회 논문집
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• 제23권3호
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• pp.65-74
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• 2019

본 연구에서는 노후화된 공동주택 수직 증축 리모델링 시 면진시스템의 적용성을 검토 및 면진시스템 적용을 위한 기초자료를 제공할 목적으로 동일한 구조로 수직 증축 시 수직 층수와 면진주기에 따른 최적 면진주기를 산정하였다. 해석결과, 3개층 수직 증축 시에는 면진주기를 비면진 건물 주기의 2배 이상, 2개층 수직 증축 시에는 비면진 건물 주기의 3배 이상을 확보하여야만 충분한 면진효과를 나타내는 것을 알 수 있었다. 또한, 1개층 수직 증축 시에는 비면진 건물 주기의 4배 이상을 확보하여야만 면진효과를 나타내었다. 위의 결과를 활용하여 3개층 수직증축 리모델링 대상 공동주택에 면진시스템을 적용하여 그 효과를 검증하였다. 최상층 최대응답가속도가 비면진 건물의 최대응답가속도 보다 X방향의 경우에는 약 70%로, Y방향의 경우에는 약 65%의 감소를 나타내었다. 또한, 밑면 전단력의 경우, 비면진 건물과 비교하여 X방향 및 Y방향 모두 약 30% 감소하는 것으로 나타났다.

• 한국동물위생학회지
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• 제14권1호
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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.

• 한국소음진동공학회논문집
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• 제17권7호
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.831-836
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• 2006

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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.185-190
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• 2007

최근 반도체 및 디스플레이 산업 등에서 초정밀 가공, 측정 등이 필요함에 따라, 외란과 내부 진동을 차단하는 방진 시스템에 대한 연구가 활성화 되고 있다. 기존에 소개된 여러 방진 시스템 중에서 가장 많이 연구되는 공기스프링은 압축 공기를 이용하여 큰 하중을 지지할 수 있으면서 상대적으로 낮은 강성으로 낮은 고유진동수를 유지할 수 있다. 본 연구는 기존의 레벨링 밸브를 이용한 수동 방진 시스템을 분석하여 이를 개선하고 능동 방진 시스템을 설계한다. 공기의 비선형 특성에 기인하는 복잡한 비선형 시스템 제어에 PID 제어기 보다 유리한 퍼지 제어기를 설계하였고, 실험과 해석을 비교하였다.