• Fire Science and Engineering
• /
• v.30 no.1
• /
• pp.17-23
• /
• 2016

Membrane structures can be used to create diverse lightweight structural forms using ductile membranes made of coated fabric. Using membrane structures, it is possible to construct large covered spaces relatively quickly and economically, and hence, they are being applied within various applications. The structures are light-weight, transparent, flexible in their application, economical and easy to maintain, and as such, their usage is being expanded. However, despite their prevalence, the standard for membrane material performance in terms of fire safety is still inadequate, and the development of membrane materials with excellent flame resistance performance is being demanded. This study determined flame resistance performance of architectural membranes, including PTFE, PVDF, PVF and ETFE film membranes, through flammability testing and incombustibility testing.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.445-448
• /
• 2011

최근 재료 및 시공 기술의 지속적 발전으로 인하여, 사장교, 현수교 등 장대교량의 건설이 증가하고 있다. 이러한 장대교량들은 사회적 및 경제적인 중요성이 매우 크므로 교량 완공 후 유지관리 및 구조적 건전성을 모니터링하기 위하여 교량 각 주요 구조부재에 다양한 센서를 설치함으로써 교량모니터링시스템을 구축하여 외부하중에 의한 교량구조물의 거동을 감지, 수집, 분석하여 교량의 건전성을 파악하기 위하여 장대교량의 공용성과 안전성 확보에 많은 연구가 진행 되고 있으며 현재 국내외 다수의 장대교량들에는 다양한 센서로 이루어진 구조 건전성 모니터링 시스템이 설치, 운용되고 있다. 실제로 서해대교, 광안대교, 홍콩 TsingMa Bridge, 미국 Bill Emerson Memorial Bridge와 같은 실제 교량에도 적용된 바 있다. 하지만, 이상의 구조 건전성 모니터링 시스템 기술이 널리 활용되는 데는 여러 가지 장애물이 있는데, 그 중에서 가장 큰 것이 시스템을 구축하는 데 과다한 비용이 소요된다는 점이다. 예로 홍콩의 Tsing Ma 대교의 경우 350개의 센서를 설치하는데 약 8백만불이 넘는 금액이 들었으며(Farrar 등, 2004), Celeby(2002)의 보고에 의하면 각 센서의 채널 당 케이블의 설치 비용으로 약 5000불의 비용이 소모되고 있다. 이에 본 연구에서는 이러한 불편함을 극복하기 위하여 무선 센서를 개발하고, 이를 한강 상 교량 중 올림픽대교에 적용, 사장교의 구조 건전성을 저비용 및 높은 편의성으로 모니터링 하기 위한 테스트베드를 구축하여 무선 계측 시스템의 정확성 및 적용성을 확인하였다.

• Computational Structural Engineering
• /
• v.4 no.4
• /
• pp.125-133
• /
• 1991

For the purpose of efficiently calculating the design sensitivity and the reliability for the complicated structures in which the structural responses or limit state functions are given by implicit form, the probabilistic finite element method is introduced to formulate the deterministic design sensitivity analysis method and incorporated with the second moment reliability methods such as MVFOSM, AFOSM and SORM. Also, the probabilistic design sensitivity analysis method needed in the reliability-based design is proposed. As numerical examples, two thin plates are analyzed for the cases of plane stress and plate bending. The initial yielding is defined as failure criterion, and applied loads, yield stress, plate thickness, Young's modulus and Poisson's ratio are treated as random variables. It is found that the response variances and the failure probabilities calculated by the proposed PFEM-based reliability method show good agreement with those by Monte Carlo simulation. The probabilistic design sensitivity evaluates explicitly the contribution of each random variable to probability of failure. Further, the design change can be evaluated without any difficulty, and their effect on reliability can be estimated quickly with high accuracy.

• Environmental Analysis Health and Toxicology
• /
• v.21 no.3 s.54
• /
• pp.219-228
• /
• 2006

폴리우레탄, 폴리에스테르, 바이페놀, PVC 외 각종 농약 등을 생산하는 울산의 모 화학공장에서, 다양한 종류의 휘발성유기화합물질들(VOCs)이 배출되고 있다. 평균적인 휘발성유기화합물질의 배출 농도는 7283 ppm으로, 톨루엔, 페놀을 포함하여 Trimethyl-pentene, trimethyl-hexene, dimethyl-cyclohexane 등이 검출되었다. Trimethyl-pentene, trimethyl-hexene, dimethyl-cyclohexane등은 인화성이 강하며 화재를 일으킬 위험성이 매우 큰 것으로 알려져 있고, 특히 톨루엔과 페놀의 경우는 호흡이나 피부접촉 등을 통한 인체로의 유입이 있을 경우 유독성을 나타내게 된다. 이러한 VOCs제거를 위하여 겨울철 기간에 파이로트-규모의 바이오필터 적용 실험이 진행되어 졌다. 본 연구의 목적은 바이오필터 운영이 진행되는 가운데 온도, 함수비, 하중, 압력손실 등의 제한요소들이 미디어 내부에서 변화하는 상황에 대한 관찰 및 평가에 있다. 이러한 제한요소들은 바이오필터의 디자인과 오염물질 제거에 심대한 영향을 미치게 된다. 바이오필터는 옥외에 설치되어 총 44일간 운영되어 졌는데, 외부 영하온도의 영향을 최소화하기 위하여, 7cm두께의 파이버-글래스 소재 단열설비가 반응기 외부에 설치되었고 또한 $150^{\circ}C$의 스팀이 바이오필터 반응기와 단열설비 사이에 제공되어 졌다. 바이오필터 반응기 내부에는 23개의 온도 측정 센서와 함수비 센서, 공기샘플포트, 습도계 등이 각기 다른 장소에 설치되어 온도, 함수비 등의 제한요소 영향연구가 진행되었다. 미디어 내부 같은 높이의 서로 반대되는 위치에서 온도차가 13.7도에서 -8.3도까지 차이가 나는 것으로 관찰되었으며, 미디어 높이 위치의 변화에 따라서도 21도에서 2도가지 차이를 나타냈다. 바이오필터 함수비는 실험기간 동안 지속적으로 변화가 발생하였는데, 스팀이 제공되는 동안에는 미디어 함수비가 훨씬 빠른 속도로 증가됨이 관찰되어 졌다.

• Journal of Korean Association for Spatial Structures
• /
• v.12 no.1
• /
• pp.77-85
• /
• 2012

The membrane structure maintains stable form by giving initial tension to ductile membrane and increasing the stiffness of exterior that is much adopted in the large span spatial structure by making its thickness thin. This kind of membrane structure has characteristic that can express free-form curve, so the selection of structural form is very important. So, this paper proposes the expression of free-form surface based on NURBS basis function and the finite element method considering geometrical nonlinearity for the deduction of large deformation result. Also, for minimizing the approximation of the surface that is derived from the form-finding result, the interface method that change finite element mesh to NURBS is proposed. So, the optimum surface of free-form membrane is derived.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.8
• /
• pp.62-69
• /
• 2010

Many electric poles in the softground have been collapsed due to external load. In this study, 10 types of tests were performed with variation of location, numbers and depths of anchor blocks as well as depth of poles to find horizontal earth pressure through full scale pull-out tests. The horizontal earth pressure increased with embedded depth of electric pole, and earth pressure of lower passive zone decreased. The deeper of anchor block, earth pressure of passive zone becomes less. 4 anchor blocks decreased earth pressure at G.L.-0.9[m]. It is considered that 4 anchor blocks installed along 80[cm] vertically are main reason. Overall, when more anchor blocks are constructed, excavation area is large, and constructivity such as backfill is bad, therefore one anchor block would be preferred.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.22 no.1
• /
• pp.22-31
• /
• 2002

A Safety Monitoring System using a laser and 2-D arrayed photo sensors is developed. To monitor of the deformation and small rotation of structure the developed optical system using 2-D photo sensor array was used to detect the variation of optical orbit of laser which was induced by deformation of the structure. Also, an operating program to manage the system and an algorithm for the data acquisition and the database are introduced. In this study, we demonstrated the capabilities of this system by laboratory experiments before applying the system to the field.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.6 no.4
• /
• pp.225-232
• /
• 2002

Recently the slab span-jointing method has been employed as one of the retrofit technologies to enhance the capacity of existing simple beam bridges in many cases. In general this method makes simple beam bridges behave like multi-span continuous bridges under service loads excluding self weight in company with external prestress force method in the field. In this paper the continuation effect has been studied for the retrofitted bridges by the experimental and numerical approaches. The results show that the deflections and stresses of members are reduced due to the increase of the total stiffness of bridge system and the efficiency of bridge continuation based on the slab span-jointing method is about 40 % when comparing with the case of continuous bridges.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.11 no.1
• /
• pp.15-22
• /
• 2011

In this research, static load test is performed to verify the arch effect and structural performance of CFTA(Concrete-Filled and Tied steel tubular Arch) girder, and FE(Finite Element) analysis is performed to investigate validity of the test result. CFTA girder is designed to maximize the benefit of each material, such as steel plate, filled concrete and PS tendon. Static load test is performed based on the frame-analysis result of 12m sample miniature model. The result of static load test is that structural performance and safety of CFTA girder are confirmed and there is different deflection mode with other structural form result from arch effect. FE analysis with ABAQUS is also performed to show the validity of the truck collision safety and static load test.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.3
• /
• pp.21-28
• /
• 2022

The TMD has a simple structure than other vibration control devices and shows excellent control performance for the simple harmonic vibration generated in the structure. However, the vibration control range is narrower than other control devices, making it vulnerable to vibration cycles caused by unexpected external loads. The ETMD developed in this study consisted of Mass with electromagnets. Therefore when supplying a current, the magnetic field is formed to increase the friction force with the friction plate, thereby instantaneously controlling the behavior of the Mass. The experiment was conducted to compare the control performance of the control device by installing the ETMD developed for control performance evaluation in the center of the model simple beam bridge to forced excitation at 3.02 Hz where the maximum bending displacement occurs. As a result of the experiment, ETMD exhibited excellent control performance with a maximum bending displacement attenuation rate of 57.51%.