• Structural Engineering and Mechanics
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• 제81권3호
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• pp.281-292
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• 2022

This study aimed to analyze the dynamic punching shear performance of slab-column joints under cyclic loads with the use of double-hooked end (5D) steel fibers. Structural systems such as slab-column joints are widely found in infrastructures. The susceptibility to collapse of such structures when submitted to seismic loads is highly dependent on the structural performance of the slab-column connections. For this reason, the punching capacity of reinforced concrete (RC) structures has been the subject of a great number of studies. Steel fibers are used to achieve a certain degree of ductility under seismic loads. In this context, 5D steel hooked fibers provide high levels of fiber anchoring, tensile strength and ductility. However, only limited research has been carried out on the performance under cyclic loads of concrete structural members containing steel fibers. This study covers this gap with experimental testing of five different full-scale subassemblies of RC slab-column joints: one without punching reinforcement, one with conventional punching reinforcement and three with 5D steel fibers. The subassemblies were tested under cyclic loading, which consisted of applying increasing lateral displacement cycles, such as in seismic situations, with a constant axial load on the column. This set of cycles was repeated for increasing axial loads on the column until failure. The results showed that 5D steel fiber subassemblies: i) had a greater capacity to dissipate energy, ii) improved punching shear strength and stiffness degradation under cyclic loads; and iii) increased cyclic loading capacity.

• Earthquakes and Structures
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• 제11권2호
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• pp.315-326
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• 2016

This paper presents the results of cyclic loading tests on concrete beams reinforced with various reinforcement, including ordinary steel bars, CFRP bars and CFRP prestressed concrete prisms(PCP). The main variable in the test program was the level of prestress and the cross section of PCP. The seismic performance indexes including hysteretic loops, skeleton curve, ductility, energy dissipation capacity and stiffness degradation were analyzed. The results show that the CFRP prestressed concrete prisms as flexural reinforcement of concrete beams has good seismic performance. And the ductility and the energy dissipation capacity were good, the hysteresis loops were full and had large area.

• Computers and Concrete
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• 제19권3호
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• pp.227-232
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• 2017

This paper describes an experimental study of the cyclic performance of concrete beams reinforced with CFRP prestressed concrete prisms (PCP). The failure modes, hysteretic loops, skeleton curve, ductility, energy dissipation capacity and stiffness degradation of concrete beams reinforced with CFRP prestressed concrete prisms were analyzed. The results show that The CFRP prestressed prisms reinforced concrete beams have good seismic performance. The level of effective prestress and cross section of CFRP prestressed prisms had a little influence on the bearing capacity, the ductility and energy dissipation capacity of CFRP prestressed prisms reinforced concrete beams.

• 전기전자학회논문지
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• 제16권1호
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• pp.51-55
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• 2012

본 논문에서는 순환천이변조 (CCSK: cyclic code shift keying) 시퀀스로 삼진 시퀀스를 적용하는 것을 제안하였다. 그리고 순환천이변조를 적용한 주파수도약대역확산/시분할다중접속 (FHSS/TDMA: frequency hopping spread spectrum/time division multiple access) 시스템에서 성능을 모의실험 하였다. 실험에서 무선 채널은 레일레이(Rayleigh) 페이딩 채널로 모델링하였다. 모의 실험 결과로부터 순환천이변조 시퀀스로 무작위 시퀀스를 사용한 시스템보다 삼진 시퀀스를 적용한 시스템이 더 높은 성능을 보이는 것이 증명되었다.

• Structural Engineering and Mechanics
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• 제64권3호
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• pp.301-310
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• 2017

For further development of passive control systems to dissipate larger seismic energy and prevent the structures from earthquake losses, this paper proposes an innovative two-level control system to improve behavior of chevron braced steel frames. Combining two Knee Braces, KB, and a Vertical Link Beam, VLB, in a chevron braced frame, this system can reliably sustain main shock and aftershocks in steel structures. The performance of this two-level system is examined through a finite element analysis and quasi-static cyclic loading test. The cyclic performances of VLB and KBs alone in chevron braced frames are compared with that of the presented two-level control system. The results show appropriate performance of the proposed system in terms of ductility and energy dissipation in two different excitation levels. The maximum load capacity of the presented system is about 30% and 17% higher than those of the chevron braced frames with KB and VLB alone, respectively. In addition, the maximum energy dissipation of the proposed system is about 78% and 150% higher than those of chevron braced frames with VLB and KB respectively under two separate levels of lateral forces caused by different probable seismic excitations. Finally, high performance under different earthquake levels with competitive cost and quick installation work for the control system can be found as main advantages of the presented system.

• 대한전자공학회논문지TC
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• 제47권6호
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• pp.42-48
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• 2010

군용 통합 전술 정보 통신 체계(JTIDS: Joint Tactical Information Distribution System)에서 사용하는 기저대역 변조 방식 중 하나인 순환 부호 편이 변조 (CCSK: Cyclic Code Shift Keying) 방식은 5개의 비트를 32개의 32칩 수열로 변환하는 일종의 직접 수열 기반 대역 확산 변조 방식이다. 순환 부호 편이 변조 방식은 총 32개의 비직교 수열을 사용한다. 본 논문에서는 CCSK를 기반으로 하는 비동기 검파 성능을 분석하였다. 또한, 보다 나은 성능을 가지는 32칩 수열을 제안하고, 종래의 32칩 수열과 성능을 비교하였다.

• 한국동물학회지
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• 제37권4호
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• pp.565-572
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• 1994

연두금파리의 유충-번데기-성충의 발생에 따른 cyclic AMP(CAMP)와 ecdysteroids의 농도 및 cyclic AMP-dependent protein kinase(PKA)의 활성도를 High Performance Liquid Chromatography(HPLC)와 Liquid Scintillation Counter(LSC)를 이용하여 측정하고 상관 기능 변화를 조사하였다. CAMP의 농도와 PKA의 활성도는 종령유충 및 성충에서 낮은 갓(0.29 UM/g, 5.52~5.59 unit/mg)을 나타내었고 번데기 0일(0.49 UM/g. 92.22 unit/mg)과 7일(0.50UM/g, 24.45 unit/mg)에서 최고치를 보였으며 번데기 4일에서 최저수준(0.13 $\mu$M/g3.23 unit/mg)을 나타내었다. Ecdysone 농도는 번데기 2일에 최고치(37 84 USlg)를 4일에 최저치(18.46 Ugyg)를 보인 후, 5일에 24.37 1519로 상승하였으며 성충에서는 낮은 값을 나타내었다 그러나 20-hydroxvecdysone 농도는 번데기 4일(23.66 UgyS)과 번데기 6일(14.90 Ugyg)에 최고치를 이루었고, 7일에서 최저치(1.21 USi9)를 나타내었다.

• Steel and Composite Structures
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• 제21권3호
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• pp.517-536
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• 2016

Thick steel plate is commonly found with mega steel structures but its properties have not been fully explored. Grade Q345GJ-C steel plate with thickness ranging from 60 mm to 120 mm are studied in this paper. Both the static and cyclic performance of material in different directions (horizontal and through-thickness directions) and locations (outer surface, 1/4 thickness and mid-depth) are experimentally obtained. The accumulative damage during cyclic loading is also calculated by using bilinear mixed hardening (BMH) constitutive relationship together with the Lemaitre's damage model. Results show that the static properties are better at the outer surface of thick steel plates than those at mid-depth. Properties in through-thickness direction are similar to those at mid-depth in the horizontal direction. The cyclic performance at different locations of a given plate is similar within the range of strain amplitude studied. However, when damage parameters identified from monotonic tensile tests are included in the numerical simulation of cyclic loading tests, damage is found accumulating faster at mid-depth than close to outer surface.

• 한국정보통신학회논문지
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• 제19권8호
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• pp.1839-1844
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• 2015

Low-density parity-check(LDPC) 코드는 우수한 에러 정정 능력으로 인해 점점 많은 통신 표준에서 채택되고 있으며 그 중 구현이 용이한 quasi-cyclic LDPC(QC-LDPC)가 많이 사용되고 있다. QC-LDPC 복호기에서는 데이터들을 rotation할 수 있는 cyclic-shifter가 필요하며, 이 cyclic-shifter는 다양한 크기의 rotation을 수행할 수 있어야 한다. 이러한 cyclic-shifter를 multi-size circular shifter(MSCS)라고 부르며, 이 논문에서는 MSCS를 적은 면적으로 구현한 구조를 제안한다. 기존의 직렬로 배치된 barrel-rotator 구조에서 rotation의 성질을 이용하여 필요 없는 멀티플렉서를 가려내고 이들을 제거함으로써 저면적을 구현하였다. 실험 결과 면적을 약 12% 줄일 수 있었다.

• 한국공간구조학회논문집
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• 제15권2호
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• pp.61-68
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• 2015

The performance enhancement of various structural building systems from natural hazards has become an inctreasingly important issue in engineering field. In this paper, visco-elastic(VE) CST30 damping systems were tested under cyclic loadings to evaluate their performance in terms of ductility and energy dissipation. Main test variables are relative shear stiffness, rate of loading frequency, and thickness of specimens to evaluate the seismic capacity based on the performance criteria. This experiment was performed using a total of 12 specimens, subjected to cyclic loadings up to a shear deformation of 500%. All the CST30 dampers provided a ductile and stable hysterestic behavior when subjected to the demands of large shear stiffness and different loading frequencies. The test results showed that the CST30 dampers are an effective damping systems to enhance the buildings performance for remodeling and retrofit of buildings.