• Title/Summary/Keyword: field static test

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Development and Application of Cone Penetrometer with Impact Penetration Rod for Evaluation of Track Substructure (철도궤도 하부구조물 평가를 위한 타격식 관입 롯드가 체결된 콘 관입기의 개발 및 적용)

  • Hong, Wontaek;Byun, Yonghoon;Kim, Sangyeob;Choi, Chanyong;Lee, Jongsub
    • Journal of the Korean GEO-environmental Society
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    • v.16 no.2
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    • pp.45-52
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    • 2015
  • To minimize the cost of maintenance, repair and over-design of track substructure, an accurate evaluation of strength and stiffness of the track substructure is necessary. In this study, a cone penetrometer with impact penetration rod (CPI) is developed for the evaluation of track substructure. For applicability test, the chamber and field tests were performed. As the experimental results of the CPI, dynamic cone penetration endex (DCPI), cone tip resistance ($q_c$), friction resistance ($f_s$) and friction ratio (Fr) were obtained. In the chamber test, the experimental results show reasonable values for the simulated track substructure. In the field test, the CPI clearly detects the interface between the ballast and the subgrade. Also, discontinuous layers are detected in the subgrade. It is expected that the developed CPI may be an effective tool for the evaluation of track substructure by evaluating the ballast layer by dynamic penetration and the subgrade by static penetration of the inner rod.

Evaluation of Structural Performance and Dynamic Characteristics of Korean Traditional Timber Structure Sungnyemun (한국 전통 목조건축 숭례문의 구조성능 및 동적특성 평가)

  • Kim, Yeong-Min
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.6
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    • pp.607-614
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    • 2015
  • In this research, the structural analysis and safety evaluation for Sungnyemun -No.1 national treasure of Korea- was performed. Roof loads were calculated in detail, and structural analysis model was constructed using Midas Gen ver.820. Static structural analysis under vertical loads was performed and safety of main structural members and serviceability of main horizontal members were evaluated. To evaluate dynamic characteristics of Sungnyemun, both field measurements by impact hammer test and eigenvalue analysis by structural analysis software were performed and the results were compared. Sungnyemun showed rooms in their structural capacity.

A Study on the Development and the Uncertainty Analysis of Oil Flow Standard System (기름 유량표준장치의 개발 및 측정 불확도에 관한 연구)

  • Lim, Ki-Won;Choi, Jong-Oh
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.8
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    • pp.1071-1080
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    • 2003
  • A national standard system was developed in order to calibrate and test the oil flowmeters for the petroleum field. A stop valve and a gyroscopic weighing scale were employed for the primary standard of the flow quantity. It is operated by the standing start and finish mode and the static weighing method. The model equation for uncertainty evaluation was based on the calibration principle of standard system. The sources of the uncertainties were quantified and combined according to the GUM(Guide to the Expression of Uncertainty in Measurement). It was found that the standard system had the relative expanded uncertainty of 0.04 % in the range of 18 - 350 ㎥/h. According to the uncertainty budget, the uncertainties of the fluid density and the volume of pipeline, which were temperature dependent, contributed 92% of final uncertainty in the oil flow standard system.

Liquid Cooling System Using Planar ECF Pump for Electronic Devices (평면형 ECF 펌프를 이용한 전자기기 액체냉각 시스템)

  • Seo, Woo-Suk;Ham, Young-Bog;Park, Jung-Ho;Yun, So-Nam;Yang, Soon-Young
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.12
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    • pp.95-103
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    • 2007
  • This paper presents a liquid cooling concept for heat rejection of high power electronic devices existing in notebook computers etc. The design, fabrication, and performance of the planar ECF pump and farced-liquid cooling system are summarized. The electro-conjugate fluid (ECF) is a kind of dielectric and functional fluids, which generates jet flows (ECF-jets) by applying static electric field through a pair of rod-like electrodes. The ECF-jet directly acts on the working fluid, so the proposed planar ECF pump needs no moving part, produces no vibration and noise. The planar ECF pump, consists of a pump housing and electrode substrate, achieves maximum flow rate and output pressure of $5.5\;cm^3/s$ and 7.2 kPa, respectively, at an applied voltage of 2.0 kV. The farced-liquid cooling system, constructed with the planar ECF pump, liquid-cooled heat sink and thermal test chip, removes input power up to 80 W keeping the chip surface temperature below $70\;^{\circ}C$. The experimental results demonstrate that the feasibility of forced-liquid cooling system using ECF is confirmed as an advanced cooling solution on the next-generation high power electronic devices.

A comprehensive high Reynolds number effects simulation method for wind pressures on cooling tower models

  • Cheng, X.X.;Zhao, L.;Ge, Y.J.;Dong, J.;Demartino, C.
    • Wind and Structures
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    • v.24 no.2
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    • pp.119-144
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    • 2017
  • The traditional method for the simulation of high Reynolds number (Re) effects on wind loads on cooling tower models in wind tunnels focuses only on the mean wind pressure distribution. Based on observed effects of some key factors on static/dynamic flow characteristics around cooling towers, the study reported in this paper describes a comprehensive simulation method using both mean and fluctuating wind pressure distributions at high Re as simulation targets, which is indispensable for obtaining the complete full-scale wind effects in wind tunnels. After being presented in this paper using a case study, the proposed method is examined by comparing the full covariance matrices and the cross-spectral densities of the simulated cases with those of the full-scale case. Besides, the cooling tower's dynamic structural responses obtained using the simulated wind pressure fields are compared with those obtained by using the full-scale one. Through these works, the applicability and superiority of the proposed method is validated.

A Study on Visual Perception based Emotion Recognition using Body-Activity Posture (사용자 행동 자세를 이용한 시각계 기반의 감정 인식 연구)

  • Kim, Jin-Ok
    • The KIPS Transactions:PartB
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    • v.18B no.5
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    • pp.305-314
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    • 2011
  • Research into the visual perception of human emotion to recognize an intention has traditionally focused on emotions of facial expression. Recently researchers have turned to the more challenging field of emotional expressions through body posture or activity. Proposed work approaches recognition of basic emotional categories from body postures using neural model applied visual perception of neurophysiology. In keeping with information processing models of the visual cortex, this work constructs a biologically plausible hierarchy of neural detectors, which can discriminate 6 basic emotional states from static views of associated body postures of activity. The proposed model, which is tolerant to parameter variations, presents its possibility by evaluating against human test subjects on a set of body postures of activities.

Multiple crack evaluation on concrete using a line laser thermography scanning system

  • Jang, Keunyoung;An, Yun-Kyu
    • Smart Structures and Systems
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    • v.22 no.2
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    • pp.201-207
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    • 2018
  • This paper proposes a line laser thermography scanning (LLTS) system for multiple crack evaluation on a concrete structure, as the core technology for unmanned aerial vehicle-mounted crack inspection. The LLTS system consists of a line shape continuous-wave laser source, an infrared (IR) camera, a control computer and a scanning jig. The line laser generates thermal waves on a target concrete structure, and the IR camera simultaneously measures the corresponding thermal responses. By spatially scanning the LLTS system along a target concrete structure, multiple cracks even in a large scale concrete structure can be effectively visualized and evaluated. Since raw IR data obtained by scanning the LLTS system, however, includes timely- and spatially-varying IR images due to the limited field of view (FOV) of the LLTS system, a novel time-spatial-integrated (TSI) coordinate transform algorithm is developed for precise crack evaluation in a static condition. The proposed system has the following technical advantages: (1) the thermal wave propagation is effectively induced on a concrete structure with low thermal conductivity of approximately 0.8 W/m K; (2) the limited FOV issues can be solved by the TSI coordinate transform; and (3) multiple cracks are able to be visualized and evaluated by normalizing the responses based on phase mapping and spatial derivative processes. The proposed LLTS system is experimentally validated using a concrete specimen with various cracks. The experimental results reveal that the LLTS system successfully visualizes and evaluates multiple cracks without false alarms.

Study of Failure Mode and Static Behavio of Lightweight FRP Bridge Deck System (복합재료 교량 시스템의 정적거동 분석 및 파괴모드에 관한 연구)

  • Jung Woo-Young;Lee Hyung-Kil;An Byoung-Yun;Baek Sang-Hoon
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2006.04a
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    • pp.922-927
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    • 2006
  • There is a concern with worldwide deterioration of highway bridges, particularly reinforced concrete. The advantages of fibre reinforced plastic(FRP) composites over conventional materials motivate their use in highway bridges for replacement of structures. Recently, an FRP deck has been installed on a state highway, located in New York State, as an experimental project. In this paper, a systematic approach for analysis of this FRP deck bridge is presented. Multi-step linear numerical analyses have been performed using the finite element method to study the structural behavior and the possible failure mechanism of the FRP deck-superstructure system Deck's self-weight and ply orientations at the interface between steel girders and FRP deck are considered in this study. From this research, the results of the numerical analyses were corroborated with field test results. Analytical results reveal several potential failure mechanism for the FRP deck and truss bridge system The results presented in this study may be used to propose engineering design guideline for new and replacement FRP bridge deck structure.

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Load Capability in a Bending Piezoelectric Composite Actuator with a Thin Sandwiched PZT Plate (굽힘 압전 복합재료 작동기의 하중 특성)

  • Woo, Sung-Choong;Goo, Nam-Seo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.8
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    • pp.880-888
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    • 2007
  • This article describes the load capability of bending piezoelectric actuators with a thin sandwiched PZT plate in association with the stored elastic energy induced by an increased dome height after a curing process. The stored elastic energy within the actuators is obtained via a flexural mechanical bending test. The load capability is evaluated indirectly in terms of an actuating displacement with a load of mass at simply supported and fixed-free boundary conditions. Additionally, a free displacement under no load of mass is measured for a comparison with an actuating displacement. The results reveal that an actuator with a top layer having a high elastic modulus and a low coefficient of thermal expansion exhibits a better performance than the rest of actuators in terms of free displacement as well as actuating displacement due to the formation of the large stored elastic energy within the actuator system. When actuators are excited at AC voltage, the actuating displacement is rather higher than the free displacement for the same actuating conditions. In addition, the effect of PZT ceramic softening results in a slight reduction in the resonance frequency of each actuator as the applied electric field increases. It is thus suggested that the static and dynamic actuating characteristics of bending piezoelectric composite actuators with a thin sandwiched PZT plate should be simultaneously considered in controlling the performance.

Fatigue study on additional cutout between U shaped rib and floorbeam in orthotropic bridge deck

  • Ju, Xiaochen;Zeng, Zhibin;Zhao, Xinxin;Liu, Xiaoguang
    • Steel and Composite Structures
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    • v.28 no.3
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    • pp.319-329
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    • 2018
  • The field around additional cutout of the floor beam web in orthotropic bridge deck was subjected to high stress concentration, especially the weld toe between floor beam and U shaped rib and the free edge of the additional cutout. Based on different considerations, different geometrical parameters of additional cutout were proposed in European, American and Japanese specifications, and there remained remarkable differences among them. In this study, considering influence of out-of-plane deformation of floor beam web and U shaped rib, parameter analysis for additional cutout under typical load cases was performed by fine finite element method. The influence of additional cutout shape and height to the stress distribution around the additional cutout were investigated and analyzed. Meanwhile, the static and fatigue test on this structure details was carried out. The stress distribution was consistent with the finite element analysis results. The fatigue property for additional cutout height of 95mm was slightly better than that of 61.5 mm.