• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.303-310
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• 2009

CFRP(carbon fiber reinforced polymer) tendons can be used as an alternative to solve the corrosion problem of steel tendons. Material properties of CFRP tendons such as bond strength, transfer length, and development length should be determined in order to apply to concrete structures. First of all, in case of application for pretension concrete members with CFRP tendons, transfer length is an important factor. A total of 9 beams have been cast to determine transfer length and development length of domestic CFRP tendon in this paper. Test results revealed that transfer length of the prestressing 25% and 50% are 34D, 55D respectively. Also, transfer length has increased as the prestressing force has increased. A change was observed in transfer length of developed CFRP tendon after 9 weeks. ${\alpha}_t$ of developed CFRP tendon was 2.3 similar to the steel strand.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.723-731
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• 2016

In pretensioned concrete members, a certain bond length from the end of the member is required to secure the effective prestress in the strands, which is defined as the transfer length. However, due to the complex bond mechanism between strands and concrete, most transfer length models based on the deterministic approach have uncertainties and do not provide accurate estimations. Therefore, in this study, Adaptive Neuro-Fuzzy Inference System (ANFIS), a Neuro-Fuzzy System, is introduced to reduce the uncertainties and to estimate the transfer length more accurately in pretensioned concrete member. A total of 253 transfer length test results have been collected from literatures to train ANFIS, and the trained ANFIS algorithm estimated the transfer length very accurately. In addition, a design equation was proposed to calculate the transfer length based on parametric studies and dimensional analyses. Consequently, the proposed equation provided accurate results on the transfer length which are comparable to the ANFIS analysis results.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.293-302
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• 2004

The transfer of prestress force in pretensioned prestressed concrete (PSC) members is of great concern because it affects directly the distribution of stress around the transfer zone. The design provision of current design code on the transfer length considers only the prestress intensity and the diameter of prestressing steels. However, other factors such as concrete compressive strength and concrete cover may affect greatly the transfer length. The purpose of the present paper is to explore the various factors that affect the transfer length in pretensioned PSC members. The bond stress-slip relation between prestressing steel and concrete was modeled first from experimental data and then this model was incorporated into the interface element. The interface element was used to perform the finite element analysis for pretensioned PSC members. The results indicate that the compressive strength and concrete cover are also very important parameters which affect the transfer length greatly. This means that the current design code, which considers only the effective prestress and diameter of prestressing steel, must be improved to take into account the other important variables of compressive strength and concrete cover. The present study allows more realistic analysis and design of pretensioned PSC members.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.707-714
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• 2015

In this paper, an experimental program has been conducted to investigate transfer length in high strength concrete members pretensioned through a seven-wire strand with FBG sensors. To measure transfer length, five members were fabricated, which had a length of 3 m and a cross-section of $150{\times}150mm$. It was measured that the concrete compressive strength was 58MPa at pretensioning. Test results indicated that more precise and reliable measurement on the transfer length was attained with FBG sensors than conventional gauges attached on concrete surface. Through comparing the measured transfer length and predictions, applicability of several transfer length models in literature was investigated. This paper can be useful for relevant research field such as investigation on the bond mechanism of a seven-wire strand in concrete members.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.336-341
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• 2018

The prestressing force introduced to the tendon in pretensioned concrete members is transferred by direct bond between tendon and concrete, which requires a proper estimation of stress transfer length. The use of pretensiond and/or precast members with UHPC (Ultra High Performance Concrete) may give many advantages in quality control. This paper presents an experiment to estimate the stress transfer length of UHPC for various compressive strength levels of UHPC, cover depths, diameters of tendons and tensioning forces. According to the result of this experiment, the stress transfer length of UHPC member is much reduced comparing that of normal strength concrete. The reduction in stress transfer length of UHPC may come from the high bond strength capacity of UHPC. The transfer lengths obtained from this experiment are compared to those in current design code and a new formula is proposed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.407-410
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• 2003

현재 통신시스템에서 많이 사용되고 있는 Xilinx FPGA를 이용하여, 여러 가지 로직을 구현하고 데이터 전달특성을 분석하기 위하여 신호의 노이즈와 데이터 손실을 방지하기 위하여 10층의 PCB(Printed Circuit Board)를 만들었다. FPGA에 클럭과 64bit의 데이터를 동기 시켜 전송선로의 길이의 변화와 입력된 클럭의 주파수 변화에 따른 최대 안정된 데이터 전달속도와 전송선로의 길이를 알아보았다. 제작된 PCB보드에서 FPGA의 출력 핀에서 출력포트 사이의 전송선로 길이는 13cm이며 확장된 테스트용 전송선로 보드의 길이는 30cm, 60cm, 120cm이다. 그러므로 전송선로의 길이를 13cm, 43cm, 73cm, 133cm간격으로 측정하였으며, 데이터 전송특성에 대한 클럭 주파수는 10MHz, 50MHz, 100MHz, 125MHz, 150MHz로 나누어 측정하였다. 데이터 전달 특성에서 125Mbps까지는 불가능 하지만 전송선로의 길이가 30cm일 경우 최대 100Mbps까지 안정하게 데이터를 전달할 수 있었다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.395-401
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• 2022

In this study, the transfer length of strand was measured for three types of HCS member(H200, H320, and H400) manufactured by the pretension method. Strain gauges were attached in longitudinal direction at regular intervals on the sides of the HCS members, and the strain was measured during the cutting process of HCS. The stain at the cutting point was zero, and gradually increases in the central direction of the member, converging to a constant value after passing the transfer length. In the case of H200 members in which the strands were arranged one by one, the transfer lengths were formed within the range of the design equation (up to 762 mm). The transfer length of the H320 member and the H400 member, in which three strands were arranged, was higher than the design range (850 mm or more).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1277-1281
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• 2005

FPGA has been widely used in communication system. In this paper, we made 10 layers PCB on protection of signal noise and data lose with FPGA. We analyzed about change of the data transmission speed and length according to input frequency. The length of transmission line from FPGA's output-pin to output-port on PCB board is 13cm and extended lengths for test are 30cm, 60cm and 10cm. We knew that data can be stably transmitted to 100Mbps at transmission line length of 30cm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.935-937
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• 2009

본 논문에서는 MicroTec을 이용한 채널 길이에 따른 20nm이하 MOSFET의 전달컨덕턴스의 특성을 분석하였다. 전달컨덕턴스는 게이트 전압의 변화에 의한 드레인 전류의 변화이다. MicroTec의 이동도 모델중 Lombardi, Constant, Yamaguchi 모델을 선택하여 이동도 모델에 따른 gm(전달컨덕턴스)를 비교하였다. 인가전압은 소스 0V, 기판 0V, 드레인 0.1V, 게이트는 -2.5V에서 4.5V까지 증가시켰다. 채널의 길이가 줄어들수록 gm(전달컨덕턴스)의 최대값과 드레인 전류가 증가함을 알 수 있었다.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.583-584
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• 2009

This is an experimental study of test parameters that have not been fully covered by previous researches in order to estimate more accurate transfer length of pretensioned, prestressed concrete members.