• Title/Summary/Keyword: RC test

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Improvement of Structural Performance for the Precast Box Culvert (지하 프리캐스트 박스 암거의 구조적 성능 개선에 관한 연구)

  • 조병완;태기호;이계삼
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.393-398
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    • 2000
  • To use concrete box culverts effectively, precast goods are manufactured at a factory, then linked and anchored with prestressing tendon at a field. However, the corrosion of rebar and prestressing tendon in the box culverts utilizing portland cement concrete is issued when the cracks occur at a underground water level. It has been reported that reported that expansive concrete, compared with portland cement concrete, has many structural advantages such as increasing capacity of watertight, controling initial crack and improving durability due to its property of expansion. During flexure test with RC beam made from expansive concrete, in the case of a constant section of concrete element, the lower steel ratio is, and in the case of a constant steel ratio, the more incremental the section of concrete element, the more incremental the amount of chemical prestress by expansive concrete is. At the segment of the box culverts using expansive concrete, the numbers of crack and its gap is reduced, and ultimate load and initial crack load is much larger than the segment at which expansive concrete is nor used. Also lay-out of tendon with a curvature generate upward force so that deflection is reduced. Through the whole procedure, it could be confirmed that performance precast box culvert by means of using expansive concrete is improved.

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A Study on the Design and Implementation of VHF band TRM for Phased Array Radar (위상배열레이다용 초단파대역 송수신모듈의 설계 및 구현에 대한 연구)

  • Kim, Ki-Jung;Shin, Seung-Gyu;Jang, Youn-Hui
    • The Journal of the Korea institute of electronic communication sciences
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    • v.13 no.2
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    • pp.321-326
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    • 2018
  • This study describes the design and implementation of TRM(Transmit and Receiver Module) for detection for targets of small RCS(Radar Cross Section). Through the pre-simulation analysis of radar system about RF, the main specifications of TRM are verified. After the fabrication of TRM, the main characteristics such as the maximum output, noise figure, spurious were confirmed. In the future, the radar system test will be carried out by assembling TRMs, antenna radiator, and the transceiver that generates and receivers the radar waveform reflected.

Micro-concrete composites for strengthening of RC frame made of recycled aggregate concrete

  • Marthong, Comingstarful;Pyrbot, Risukka N.;Tron, Stevenly L.;Mawroh, Lam-I D.;Choudhury, Md. Sakil A.;Bharti, Ganesh S.
    • Computers and Concrete
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    • v.22 no.5
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    • pp.461-468
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    • 2018
  • In this paper, to access the suitability of recycled aggregate for structural applications, concrete strength i.e., compressive, tensile and flexural strength were evaluated and compared with those specimens made of natural aggregates. Test results indicated that 30 to 42% of the mentioned strength decreases. To study the performance of frame structures made of recycled aggregate concrete (RAC) two reinforced RAC frames were prepared and tested under monotonic loading. The joint regions of one of the RAC frame were casted with micro-concrete. A reference specimen was also prepared using natural aggregate concrete (NAC) and subjected to a similar loading condition. The RAC frame resulted in a brittle mode of failure as compared to NAC frame. However, the presence of a micro-concrete at the joint region of an RAC frame improved the damage tolerance and load resisting capacity. Seismic parameter such as energy dissipation, ductility and stiffness also improves. Conclusively, strengthening of joint region using micro-concrete is found to have a significant contribution in improving the seismic performance of an RAC frame.

A Study on the Seismic Retrofit of Column in Educational Facilities Using Composite Material (복합소재를 이용한 교육시설의 기둥 내진보강공법에 관한 연구)

  • Park, Choon-Wook;Lee, Hung-Joo;Joo, Chi-Hong;Hong, Won-Hwa
    • Journal of the Korean Institute of Educational Facilities
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    • v.20 no.1
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    • pp.45-52
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    • 2013
  • In paper after the strong earthquake of recently the Korea neighborhood, the Korean government survey show that the 86% of school buildings in Korea are in potential damage risk and only 14% of them are designed as earthquake-resistance buildings. Reinforcing projects of school have been conducting by the ministry of education, however their reinforcing methods done by not proved a engineering by experiment which results in uneconomical and uneffective rehabilitation for the future earthquake. An experimental and analytical study have been conducted for the shear and flexural reinforcing method of RC beam using composite beam. Based on the previous research, in this study, performance evaluation for the column reinforcing of old school buildings using nonlinear analysis is going to be conducted and strengthening method is going to be on the market after their performance is proved by the test.

Experimental Study on the Tensile Behaviors of Stud Connection with Hanger (행거로 보강된 스터드 접합부의 인장거동에 관한 실험적 연구)

  • Kim, Seung-Hun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.4
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    • pp.231-238
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    • 2004
  • This paper presents the tensile behavior of the stud connection between reinforced concrete(RC) and steel members. Hanger reinforcements are placed around the studs to transfer the tensile and flexural loads to the opposite side of the concrete member. Eight specimens for the tensile tests are tested with variables, which are the arrangement details of hanger reinforcements, the reinforcing bars, and the embedment length of stud. The results of the tensile tests show that hanger reinforcements are effective to increase tensile strength for stud connections. Hangers and reinforcing bars near stud bolts contributed to the reduction of brittle failure. From the evaluation on the tensile strength by previous design guidelines, it was shown that CCD (Concrete Capacity Design) method was more suitable for estimation of test strength.

Development of a High Voltage Semiconductor Switch for the Command Charging o (모듈레이터의 지령충전을 위한 고전압 반도체 스위치 개발)

  • Park, S.S.;Lee, K.T.;Kim, S.H.;Cho, M.H.
    • Proceedings of the KIEE Conference
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    • 1998.07f
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    • pp.2067-2069
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    • 1998
  • A prototype semiconductor switch for the command resonant charging system has been developed for a line type modulator, which charges parallel pulse forming network(PFN) up to voltage of 5 kV at repetition rates of 60 Hz. A phase controlled power supply provides charging of the 4.7 ${\mu}s$ filter capacitor bank to voltage up to 5 kV. A solid state module of series stack array of sixe matched SCRs(1.6 kV, 50 A) is used as a command charging switch to initiate the resonant charging cycle. Both resistive and RC snubber network are used across each stage of the switch assembly in order to ensure proper voltage division during both steady state and transient condition. A master trigger signal is generated to trigger circuits which are transmitted through pulse transformer to each of the 6 series switch stages. A pulse transformer is required for high voltage trigger or power isolation. This paper will discuss trigger method, protection scheme, circuit simulation, and test result.

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A Tensile Criterion to Minimize FE Mesh-Dependency in Concrete Beam under Blast Loading (폭발하중을 받는 콘크리트 보의 요소의존성 최소화 인장기준식)

  • Kwak, Hyo-Gyoung;Gang, HanGul
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.2
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    • pp.137-143
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    • 2017
  • A tensile failure criterion that can minimize the mesh-dependency of simulation results on the basis of the fracture energy concept is introduced, and conventional plasticity based damage models for concrete such as CSC model and HJC model, which are generally used for the blast analyses of concrete structures, are compared with orthotropic model in blast test to verify the proposed criterion. The numerical prediction of the time-displacement relations in mid span of the beam during blast loading are compared with experimental results. Analytical results show that the numerical error is substantially reduced and the accuracy of numerical results is improved by applying a unique failure strain value determined according to the proposed criterion.

Optimal Cooling Operation of a Single Family House Model Equipped with Renewable Energy Facility by Linear Programming (신재생에너지 단독주택 모델 냉방운전의 선형계획법 기반 운전 최적화 연구)

  • Shin, Younggy;Kim, Eui-Jong;Lee, Kyoung-ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.12
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    • pp.638-644
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    • 2017
  • Optimal cooling operation algorithm was developed based on a simulation case of a single family house model equipped with renewable energy facility. EnergyPlus simulation results were used as virtual test data. The model contained three energy storage elements: thermal heat capacity of the living room, chilled water storage tank, and battery. Their charging and discharging schedules were optimized so that daily electricity bill became minimal. As an optimization tool, linear programming was considered because it was possible to obtain results in real time. For its adoption, EnergyPlus-based house model had to be linearly approximated. Results of this study revealed that dynamic cooling load of the living room could be approximated by a linear RC model. Scheduling based on the linear programming was then compared to that by a nonlinear optimization algorithm which was made using GenOpt developed by a national lab in USA. They showed quite similar performances. Therefore, linear programming can be a practical solution to optimal operation scheduling if linear dynamic models are tuned to simulate their real equivalents with reasonable accuracy.

A Study on the Applications of GPS/Pseudolite Navigation System (GPS/의사위성의 통합 항법에 대한 응용 연구)

  • Lee Taik-Jin;Kim kang-Ho;So Hyung-Min;Kee Chang-Don;Noh Kwang-Hyun;Lee Ki-Duk
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.8
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    • pp.729-738
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    • 2006
  • In recent days, navigation technology becomes more important as location based service (LBS) such as E911 and telematics are considered as attractive business fields. Commercial LBS requires that navigation system should be inexpensive and available anytime and anywhere - indoors and outdoors. If we consider these requirements, it is out of question that GPS is the most favorite system in the world. However, GPS has a serious problem. The one is that GPS does not operate indoors well. This is because GPS satellites are about 20,000km above the ground so that indoor signals are too weak to be tracked in GPS receiver. And the other is that vertical accuracy is less than horizontal accuracy, because of GPS satellites' geometry. To solve these problems, many researches have been done around the world since 1990s. This paper is also one of them and we will introduce an excellent solution by use of pseudolite. Pseudolite is a kind of signal generator, which transmits GPS-like signal. So it is same as GPS satellite in ground. In this paper, we will propose the integrated navigation system of GPS and pseudolite and show the flight test results using RC airplane to proof our navigation system. As a result, we could improve the vertical accuracy of airplane into the horizontal accuracy.

TSV Liquid Cooling System for 3D Integrated Circuits (3D IC 열관리를 위한 TSV Liquid Cooling System)

  • Park, Manseok;Kim, Sungdong;Kim, Sarah Eunkyung
    • Journal of the Microelectronics and Packaging Society
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    • v.20 no.3
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    • pp.1-6
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    • 2013
  • 3D integrated circuit(IC) technology with TSV(through Si via) liquid cooling system is discussed. As a device scales down, both interconnect and packaging technologies are not fast enough to follow transistor's technology. 3D IC technology is considered as one of key technologies to resolve a device scaling issue between transistor and packaging. However, despite of many advantages, 3D IC technology suffers from power delivery, thermal management, manufacturing yield, and device test. Especially for high density and high performance devices, power density increases significantly and it results in a major thermal problem in stacked ICs. In this paper, the recent studies of TSV liquid cooling system has been reviewed as one of device cooling methods for the next generation thermal management.