• Title/Summary/Keyword: 동하중 계수

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Wear Characteristics of Carburized SCM415 Steel for Control Valve (컨트롤 밸브용 침탄 SCM415강의 마멸 특성)

  • Lee, Jeong Won;Na, Seong Hyeon;Yoon, Dong Hyun;Han, Sun Hyoung;Kim, Hyung Gong;Kim, Jae Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.10
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    • pp.873-878
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    • 2016
  • SCM415 steel for the control valve undergoes wear because of continuous movement between the valve and valve case. The wear of the valve interrupts the performance of the valve, and decreases the service life. In this study, wear characteristics of the as-received and carburized SCM415 steels are evaluated. The wear tests are conducted for various temperatures and loads using a reciprocating wear tester. From these results, wear loss, specific wear rate, and coefficient of friction are analyzed. The wear mechanism was analyzed by SEM. The interaction effects between loads and temperatures on wear loss are determined for analysis of variance using MINITAB.

Structure Borne Noise Analysis of a Flexible Body in Multibody System (다물체계내 유연체의 구조기인 소음해석)

  • 김효식;김창부
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.11
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    • pp.882-889
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    • 2003
  • This paper presents the method for structure borne noise analysis of a flexible body in multibody system. The proposed method is the superposition method using the flexible multibody dynamic analysis and the finite element one. This method is executed in 3 steps. In the 1st step, time dependent quantities such as dynamic loads, modal coordinates and gross body motion of the flexible body are calculated through a flexible multibody dynamic analysis. And frequency response functions of those time dependent quantities are computed through Fourier transforms. In the 2nd step, acoustic pressure coefficients are obtained through structure-acoustic coupling analyses by the finite element method. In the final step, frequency responses of acoustic pressure at the acoustic nodes are recovered through linear superposition of frequency response functions with acoustic pressure coefficients. The accuracy of the proposed method is verified in the numerical example of a simple car model.

Measurement and Analysis of Wind Response of InCheon Bridge (인천대교의 풍응답 계측 및 분석)

  • Kim, Saang-Bum;Im, Duk-Ki;Park, Hyun-Woo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2011.04a
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    • pp.340-343
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    • 2011
  • 장대 케이블 교량의 풍응답을 계측할 수 있는 무선센서네트워크 기반의 풍응답 계측시스템을 개발하고, 이를 사용하여 인천대교의 시공단계별로 고유진동수, Mode Shape과 같은 Modal Parameters의 변화를 추정하고 보강형에서의 풍압분포와 보강형, 주탑, 케이블의 가속도를 계측하여 내풍 성능을 분석하였다. 개발된 계측 시스템은 인천대교 사장교의 전체 거동을 계측할 수 있도록, 1.5km 범위에 넓게 분포된 최대 55 Nodes에서 최대 1kHz의 동기화된 계측을 수행할 수 있으며, 각 Node별로 3축가속도나 풍압을 측정할 수 있다. 전체 Node에서 가속도를 계측하는 경우에는 최대 165 Channel을 1kHz로 측정할 수 있다. Modal 해석의 경우에, 고가교, 접속교, 사장교 주탑, 보강형, 케이블의 시공 단계별 동특성의 변화를 추정하였으며, 고가교에서는 모드해석을 통해 역추정한 구조계수를 정적재하실험 및 실험실에서의 Mold 시험결과와 비교하였으며 사장교 케이블에서는 케이블 댐퍼의 성능을 분석하였다. 또한 인천대교 보강형에서의 풍압분포를 계측하였으며, 풍압의 공간상관관계를 분석하였고, 풍하중 및 풍진동 특성을 분석하여 가속도 계측 결과와 비교하였다. 계측 및 분석 결과를 바탕으로 장대교량의 내풍성능을 확보하고 향상시키는데 활용할 수 있을 것으로 기대한다.

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Characteristics of Dynamic Properties of Granite Specimen from Chungnam Yeongi Area (충남 연기군 지역 화강암 시험편의 동적물성 특성에 관한 연구)

  • Min, June-Hyun;Lee, Seung-Joong;Choi, Sung-O.
    • Tunnel and Underground Space
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    • v.21 no.6
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    • pp.480-493
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    • 2011
  • Dynamic rock property is one of most important parameters in design of earthquake-resistant structures. In this study, free-free resonant column test has been conducted to obtain dynamic Young's modulus, dynamic shear modulus, and damping ratio among dynamic properties with granite specimen of Chungnam Yeongi area. The dynamic properties obtained from this test were compared with the physical properties from static rock tests, and their relationship has been analyzed. From our study, it has been concluded that the dynamic Young's modulus and the dynamic shear modulus are linearly proportional to the elastic wave velocity. And also the damping ratio has been identified to be in non-linear inverse proportion to the elastic wave velocity.

An Study on the Measurement of Natural Period of Apartment for Seismic Design (내진설계를 위한 공동주택의 고유주기 측정에 관한 연구)

  • Kim, Dongbaek;Lee, Byeonghoon;Lee, Kwangjae;Lee, Induk
    • Journal of the Society of Disaster Information
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    • v.11 no.4
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    • pp.487-492
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    • 2015
  • Recently, apartment designs are tend to be changed from the standard pattern by many causes and the beam-column structures are getting popular instead of wall structure system. Therefore, for the effective use of planed space the heights of apartment are tend to be higher and higher. According to Korea Building Code, earthquake resistance designs or seismic design for those high rise apartments must be more attentive and accurate, especially, dynamic periods of structures must be exactly measured, because those are very important for equivalent static analysis. The important subject of this study is to investigate the safety factors and seismic performance for natural period of high rise buildings by comparing the natural periods getting from ambient vibration method with those of Korea Building Code.

A Study on Structural Integrity and Dynamic Characteristic of Inertial Load Test Equipment for Performance Test of Railway Vehicle Propulsion Control System (철도차량 추진제어장치 성능시험을 위한 관성부하 시험설비의 구조안전성 및 동특성 평가 연구)

  • Jang, Hyung-Jin;Shin, Kwang-Bok;Lee, Sang-Hoon;Lee, Dae-Bong
    • Journal of the Korean Society for Railway
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    • v.13 no.4
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    • pp.363-370
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    • 2010
  • This paper describes the evaluation of structural integrity and dynamic characteristic of inertial load test equipments for performance test of railway vehicle propulsion control system. The propulsion control system of railway vehicle has to be confirmed of safety and reliability prior to its application. Therefore, inertial load test equipments were designed through theoretical equation for performance test of propulsion control system. The structural analysis of inertial load test equipments was conducted using Ansys v11.0 and the dynamic characteristic was evaluated using Adams. The results showed that the structural integrity of inertial load test equipment was satisfied with a safety factor of 10.2 on the bearing part under combined load. Also, the structural stability of flywheel according to dynamic simulation was secured by the maximum oscillation displacement within 0.83mm.

Element and Crack Geometry Sensitivities of Finite Element Analysis Results of Linear Elastic Stress Intensity Factor for Surface Cracked Straight Pipes (표면균열이 있는 직관에 대한 선형탄성 응력확대계수 유한요소해석 결과의 요소 및 균열형상 민감도)

  • Ryu, Dongil;Bae, Kyung-Dong;Je, Jin-Ho;An, Joong-Hyok;Kim, Yun-Jae;Song, Tae-Kwang;Kim, Yong-Beum
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.4
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    • pp.521-527
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    • 2013
  • This study provides the elastic stress intensity factors, K, for circumferential and longitudinal surface cracked straight pipes under single or combined loads of internal pressure, bending, and torsion based on three-dimensional (3D) finite element (FE) analyses. FE results are compared with two different types of defect assessment codes (API-579-1 and RCC-MR A16) to prove the accuracy of the FE results and the differences between the codes. Through the 3D FE analysis, it is found that the stress intensity factors are sensitive to the number of elements, which they were believed to not be sensitive to because of path independence. Differences were also found between the FE analysis results for crack defining methods and the results obtained by two different types of defect assessment codes.

Displacement Measurement of Cable Stayed Bridge using Digital Image Processing (디지털 영상처리를 이용한 사장교의 변위 측정)

  • Son, Byung Jik;Jeon, Seung Gon;Heo, Gwang Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.5
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    • pp.237-242
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    • 2016
  • This paper introduces a method of measuring the displacement of a cable-stayed bridge using digital image processing (DIP). The validity of the DIP technique was confirmed by comparing the results with those obtained using a displacement meter and ANSYS analysis. The normalized cross-correlation (NCC) coefficient was used. 100 kgf and 200 kgf loading experiments were carried out, which showed that when the displacement is large, the reliability of the DIP technique is increased. That is, when the load was increased from 100 kgf to 200kgf, it decreased from 31% to 14% compared to the ANSYS results and from 14% to 4% compared to the displacement meter results. Therefore, the image processing method is able to measure the displacement sufficiently accurately.

Dynamic Characteristic Analysis of 3-Piece Freight Vehicle with Wedge Friction Damper Using ADAMS (ADAMS를 이용한 3-Piece 마찰 웨지 댐퍼가 장착된 화차의 동특성 해석)

  • Lee, Chul-Hyung;Han, Myung-Jae;Park, Tae-Won
    • Journal of the Korean Society for Railway
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    • v.20 no.3
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    • pp.299-310
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    • 2017
  • In this work, an independent-load friction wedge model was developed using the ADAMS/View program to predict the performance of a freight vehicle with a bogie employing a 3-piece friction wedge. The friction wedge model can generate friction according to lateral and vertical directions of the bolster. The developed friction wedge model was applied to the ADAMS/Rail vehicle model, and results of the dynamic analysis showed a critical speed of 210km/h. In the linear safety analysis, it was confirmed that the lateral and vertical limit of acceleration of the vehicle were satisfied based on UIC518. In the 300R curve line, the application speed was 70km/h, which was satisfied with the limit acceleration of the car-body and bogie based on UIC518. Also, the developed model satisfied the wheel loading, lateral force and derailment coefficient of "The Regulations on Safety Standards for Railway Vehicles"

Investigation of the Crop Load for Tomato and Paprika in the Greenhouse (온실내 재배작물인 토마토 및 파프리카의 작물하중 검토)

  • Choi, Man Kwon;Yun, Sung Wook;Yu, Chan;Lee, Si Young;Yoon, Yong Cheol
    • Journal of Bio-Environment Control
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    • v.22 no.3
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    • pp.234-240
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    • 2013
  • The purpose of this study was to provide basic data used in greenhouse design, and for this purpose, the crop loads of tomato and paprika which have high crop load among crops cultivated in greenhouse were measured. The maximum differences in lowest and mean temperatures between cultivation year and normal years for winter season were -5.6 and $-4.9^{\circ}C$, respectively and those for summer season were 3.0 and $1.5^{\circ}C$, respectively. The calibration of push & pull gauge indicated approximate 0.99 of coefficient of determination, representing very high association. The planting densities of paprika and tomato were 3.43, 3.56 and $2.13plants{\cdot}m^{-2}$, respectively. The yields were 4.1, 4.3 and $16.2kg{\cdot}plant^{-1}$, corresponding to 14.1, 15.2 and $34.5kg{\cdot}m^{-2}$ of yield per unit area. The maximum loads were 1.3, 1.5 and $3.3kg{\cdot}plant^{-1}$, respectively. When the paprika were hanged on cross beam, the total crop load applied to it was estimated to be $15.3{\sim}15.9kg{\cdot}m^{-2}$, and when the weights of gutters supporting the cultivation beds, the total weights were $26.0{\sim}26.9kg{\cdot}m^{-2}$.