• Title/Summary/Keyword: direct test

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A study on circuit design of synthetictest facilities of capacitive current switching tests (합성 진상전류 개폐 시험설비의 회로설계에 관한 연구)

  • Kim, M.H.;Suh, Y.T.;Yoon, H.D.;Shin, Y.J.;Kang, Y.S.;Koh, H.S.
    • Proceedings of the KIEE Conference
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    • 2002.07a
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    • pp.38-40
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    • 2002
  • A study on the test method and the test facilities of synthetic capacitive current tests have been very slight and the direct test method with the short-circuit generator and power transformer only used up to now. However, according to the development of analysis technique of power system and design and manufacture technique we are realized that direct testing method is not satisfactory to evaluate the performance of circuit-breaker because it is difficult to simulate precisely the conditions of power system. Therefore, in order to solve these problem this paper deals with the tests methods and the design technique of the tests facilities of the synthetic capacitive current based on the same theory with the synthetic short-circuit tests.

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A direct XFEM formulation for modeling of cohesive crack growth in concrete

  • Asferg, J.L.;Poulsen, P.N.;Nielsen, L.O.
    • Computers and Concrete
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    • v.4 no.2
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    • pp.83-100
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    • 2007
  • Applying a direct formulation for the enrichment of the displacement field an extended finite element (XFEM) scheme for modeling of cohesive crack growth is developed. Only elements cut by the crack is enriched and the scheme fits within the framework of standard FEM code. The scheme is implemented for the 3-node constant strain triangle (CST) and the 6-node linear strain triangle (LST). Modeling of standard concrete test cases such as fracture in the notched three point beam bending test (TPBT) and in the four point shear beam test (FPSB) illustrates the performance. The XFEM results show good agreement with results obtained by applying standard interface elements in FEM and with experimental results. In conjunction with criteria for crack growth local versus nonlocal computation of the crack growth direction is discussed.

Evaluation of Interface Shear Properties Through Static Friction Tests (정적마찰 시험을 통한 접촉전단 특성평가)

  • Chang, Yong-Chai;Lee, Seung-Eun;Seo, Ji-Woong;Bowders, John J.
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.03a
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    • pp.813-818
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    • 2009
  • Shear properties of plastic bottle film/plastic bottle film and plastic bottle film/granitic soil which were evaluated from static friction tests. The monotonic shear experiments were performed by using an tilt table apparatus and large direct shear device. The test results showed that the friction angle of each interface and the interface depended on the amount of normal stress, the type of the interface used. Therefore, the testing method should be determined carefully by considering the type of loads and normal stress expected in the field with using the materials installed in the site.

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Evaluation of Interface Friction Characteristic using Waste Resource (불용 자원의 접촉면 마찰 특성 평가)

  • Lee, Seung-Eun;Chang, Yong-Chai;Bowders, John J.
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1456-1462
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    • 2008
  • This study conducted a direct shear test to evaluate friction properties on contact surface of waste resources including turban shell, gastropod shell and PET bottle film. The contact surface that was considered for computation of shear strength in contact surface were turban shell/turban shell, gastropod shell/gastropod shell, and PET bottle film/PET bottle film. As a result of test, friction angle was found to be $16.7^{\circ}$ for contact surface of turban shell/turban shell, $35.4^{\circ}$ for gastropod shell/gastropod shell, and about $11^{\circ}$ for PET bottle film/PET bottle film. Using the results, the author aims to provide a possibility for application of waste resource in the field.

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Analysis of the effects of direct overseas purchasing and sales on macroeconomic variables and electronic commerce (해외직접구매와 해외직접판매가 거시경제변수와 전자상거래에 미치는 영향 분석)

  • Jeong, Eun-Hee;Lee, Byung-Kwan
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.12 no.3
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    • pp.192-200
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    • 2019
  • This paper is analyzed causality using cointegration test and impact response after deriving a causality between direct overseas purchasing and sale and macroeconomic variables. The model used for the empirical analysis is the vector error correlation model. The model is used the macroeconomic variables such as the consumer price index and the GDP, and e-commerce variables such as direct overseas purchasing, direct overseas sales and online shopping amount. According to empirical analysis, the direct overseas purchasing has the causality with the consumer price index, and GDP has the causality with direct overseas purchasing and online. According to the impact response analysis of the VECM, the direct overseas purchasing has a positive effect on the CPI and GDP, but the direct overseas sales has a negative effect on the CPI and GDP. In addition, both direct overseas purchasing and sales have a negative effect on online shopping, but it has been shown that the direct overseas purchasing has a bigger negative effect on online shopping.

Bond Strength Properties of Latex Modified Concrete (라텍스 개질 콘크리트의 부착강도 특성)

  • 윤경구;이주형;최상릉;김기헌
    • Journal of the Korea Concrete Institute
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    • v.13 no.5
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    • pp.507-515
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    • 2001
  • Significant improvements in bond strength between new and existing concrete can be achieved through the modification of the new concrete by latex. This study focuses on the investigation of bond strength of latex modified concrete. Pull-out bond test and uniaxial direct tensile bond test are adopted for evaluating the adhesion characteristics of latex modified concrete to conventional concrete substrate. The main experimental variables are test methods, latex-cement ratio, surface preparations and moisture levels. The results are as follows; The increase of latex-cement ratio substantially improves the adhesion between latex modified concrete and substrate. The effects of surface preparation at substrate into the bonding of latex modified concrete are quite different according to the conditions of surfaces. Thus, an adequate surface preparations are essential for good bond strength. Because the moisture level of the substrate may be critical to achieving bond, optimum moisture condition for a conventional concrete has evaluated in this study. The saturated condition of surface is the most appropriate moisture level among the considered, followed by dry condition and wet condition.

Establishment of Test Field for Aerial Camera Calibration (항공 카메라 검정을 위한 테스트 필드 구축방안)

  • Lee, Jae-One;Yoon, Jong-Seong;Sin, Jin-Soo;Yun, Bu-Yeol
    • Journal of Korean Society for Geospatial Information Science
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    • v.16 no.2
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    • pp.67-76
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    • 2008
  • Recently, one of the most outstanding technological characteristics of aerial survey is an application of Direct Georeferencing, which is based on the integration of main sensing sensors such as aerial camera or Lidar with positioning sensors GPS and IMU. In addition, a variety of digital aerial mapping cameras is developed and supplied with the verification of their technical superiority and applicability. In accordance with this requirement, the development of a multi-looking aerial photographing system is just making 3-D information acquisition and texture mapping possible for the dead areas arising from building side and high terrain variation where the use of traditional phptogrammetry is not valid. However, the development of a multi-looking camera integrating different sensors and multi-camera array causes some problems to conduct time synchronization among sensors and their geometric and radiometric calibration. The establishment of a test field for aerial sensor calibration is absolutely necessary to solve this problem. Therefore, this paper describes investigations for photogrammetric Test Field of foreign countries and suggest an establishment scheme for domestic test field.

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Study on the possible application of Vibrated and Rolled reinforced concrete pipe to vertical.crossing water distribution system (진동 및 전압 철근 콘크리트관의 종.횡단배수관 적용성 검토에 관한 연구)

  • Park Do-Kyong;Lee Myung-Kue;Yang Keek-Young
    • Journal of the Korea Institute of Building Construction
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    • v.6 no.2 s.20
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    • pp.111-117
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    • 2006
  • In case of carrying out vortical crossing water distribution system in expressways or general roads construction, VR(Vibrated and Rolled reinforced concrete) pipes are restricted because of their specification of reinforced spun concrete pipe or on-site made pipe. Therefore, in order to apply VR pipes to those constructions, through the structural behavior experiments of the pipes, VR pipes are compared and verified with reinforced spun concrete pipe and the results are obtained as the following. From the experiments and analyses of Pipe Stiffness(PS) of the pipes, cracking loading is approved to satisfy the KS regulations. Through a direct load test, the cracking loading strength and the maximum load test of VR pipe is larger compared with reinforced spun concrete pipe. Particularly, even if side weld is thin, there is no little change in the cracking strength of VR pipe. The results of the direct load test analysis show that the structural behavior of VR pipe is equivalent or higher compared with reinforced spun concrete pipe in performance and VR pipe could be used as the water distribution pipe for roads. In this study, through pipe stiffness, direct load test and load teat on earth, reinforced spun concrete pipe and VR pipe are compared. And as a result, the structural behavior of VR pipe is comprehensively excellent. From the structural behavior tests, VR pipe's section shows more thickness and has uniform characteristics so that VR pipe is considered more favorable than reinforced spun concrete pipe.

An Evaluation of Lap Splice Length of Epoxy Coated Reinforcements Using Beam-End Test (보-단부 시험을 이용한 에폭시 도막 철근의 겹침 이음길이 평가)

  • Kim, Jee-Sang;Kang, Won Hyeak
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.2
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    • pp.175-182
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    • 2020
  • The application of epoxy coated reinforcements is increased as a means to prevent a corrosion of reinforcements embedded in reinforced concrete structures, However, epoxy coating may reduce the bond capacity between concrete and reinforcement, which results a longer development length and lap splice length. This paper aims to the possibility of modification in lap splice length from reduction of basic development length which was confirmed using a direct pull out test. Total 36 beam specimens were tested to compare the lap splice properties of normal and epoxy coated reinforcements with beam-end test for various lap lengths and diameters of reinforcements. According to the results on failure modes, deformations, and crack widths of this experiments, the modification factor of 1.2 should be used, though the direct bond capacity is assured through direct pull out test.

Evaluation of Characteristics of Tack Coat for Porous Pavement using Direct Shear Test (직접 전단 실험을 통한 배수성포장용 택코트 특성 평가)

  • Kim, Nak-Seok;Hong, Eun-Cheol;Jo, Shin-Haeng
    • Journal of the Korean Society of Hazard Mitigation
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    • v.9 no.1
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    • pp.27-32
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    • 2009
  • The main objective of this study is to develop a test for measuring the bond shear strength between pavement layers. The research is also conducted to evaluate tack coat materials and application rate in porous pavement. The experiment includes using two types of emulsions (RSC-4, Modified Emulsion) and a asphalt binder type (HM-1). HM-1 was developed to be applied in porous pavement. The bond shear strengths were measured by a direct shear type device under various test conditions. The shear strength may not be appropriate in the evaluation of the bond shear strength, while the toughness of the test may be useful. In case of the tack coat application rate in porous pavement, RSC-4 has to be used a minimum amount of $0.8l/m^2$ and modified emulsion asphalt has to be applied a volume of use $0.5{\sim}0.6l/m^2$. HM-1, asphalt cement type, is far stronger bond shear strength than emulsified asphalt tack coat and had showed the excellent trackless property.