• Title/Summary/Keyword: 편심도

Search Result 615, Processing Time 0.043 seconds

A Study of Rotor Fault Detection for the Induction Motor Using Axial Leakage Magnetic Flux (축방향 누설자속 측정에 의한 유도전동기의 회전자 결함검출에 관한 연구)

  • Shin, Dae-Cheul;Kim, Young-Hwan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.20 no.1
    • /
    • pp.132-137
    • /
    • 2006
  • The second part of paper related rotor failure is to evaluate that the axial magnetic flux measurement could be used as a tool of the condition monitoring system for the induction motor and to develope the diagnostic algorithm for the various fault in the electric motors. The magnetic leakage flux signal is captured by the flux coil located at the end of motor without the disturbance of the operation. And the signal is analyzed both time and frequency domain to detect the failure of the motor. Specific signature can be described in tin and frequency domain for each fault of the motor. The experimental test found that the rotor failures - broken rotor bar, broken end ing and rotor eccentricity, could be detected from the spectrum with high resolution. The method of detecting the rotor fault was found by analysing the specific frequency and the sideband of the rotor bar pass frequency from axial leakage flux spectrum. In addition the optimal flux coil and measuring equipment for the axial leakage flux measurement was verified and the diagnostic method for the detection of the rotor related failure was developed.

Development of the Hybrid CFFT Pile (FRP-콘크리트 합성말뚝의 개발)

  • Choi, Jin-Woo;Joo, Hyung-Joong;Nam, Jeong-Hun;Yoon, Soon-Jong
    • Journal of the Korean Society for Advanced Composite Structures
    • /
    • v.1 no.2
    • /
    • pp.20-28
    • /
    • 2010
  • In this paper, new type CFFT (Concrete Filled FRP Tube) was suggested in order to improve the flexural stiffness. Since the existing CFFT was produced by filament winding process, re-bar for concrete may be necessary in order to ensure structural safety under flexure re-bar. In comparison with existing type CFFT, new type CFFT was reinforced by circular shaped pultrusion FRP without re-bar. Filament winding FRP was attached to the outer layer of pultrusion FRP. Structural behavior of new type CFFT filled with concrete (HCFFT) was investigated by the mechanical property test for the component element and the FE analysis. Furthermore, compressive strength of the HCFFT member based on the equation suggested in previous studies.

  • PDF

A Study on the Cutting and Vibratory Characteristics of the Eccentrically Rotating Cutter-Bar System (편심회전 봉형 절단장치의 절단 및 진동 특성에 관한 연구)

  • 송현갑;정창주
    • Magazine of the Korean Society of Agricultural Engineers
    • /
    • v.17 no.3
    • /
    • pp.3885-3893
    • /
    • 1975
  • This work was intended to study the cutting graph and vibratory phenomina of a newly developed mower which may be suitable for mowing agricultural product having large and hard stems like corn and sugar beet. The system consists of cutter-bar having Curvilinear-translation motion, which attached to drag-crank mechanism. The motion of equation developed for experimental vibratory system which equipped with the cutter-bar system was established and the parameters defining the system's vibratory motion were experimentally determined. The optimum balancing weight for the cutter-bar am vibratory characteristics of the cutter-bar for various counterweight were analyzed to provide the design and operational conditions. The results of the study are summarized as follows; (1) The cutting graph by the new cutter-bar system depends upon the magnitude of ratio of forward travel(Vm) to crank speed (Rω); The cutting pitch for Vm/Rω 1 (whole cycle cutting) and Vm/Rω=2/π (a half cycle cutting) are 2π Vm and 4R, respectively. (2) The experimental vibratory system had been proved to function adequately so that it can be used in determining the required counterweight to minimize the vibratory motion of cutter-bar. (3) Experimentally determined counterweight to give the least vibratory motion was a little greater than the theoretically determined one. With the optimum counterweight it was possible to reduce up to about 87% of the amplitude without counterweight, which may be considered to be within safe operational region. (4) To avoid the actual operation of the cutter-bar at resonance which occured in low frequency ratio, it was considered that the rotational speed of the crank for a specific design of mower should be determined separately in connection with the desired cutting graph.

  • PDF

Reproducibility of Mandibular Eccentric Movements in Patients with Temporomandibular Disorders (측두하악장애환자에서 하악의 편심운동재현성에 관한 연구)

  • 서명석;한경수
    • Journal of Oral Medicine and Pain
    • /
    • v.22 no.2
    • /
    • pp.295-307
    • /
    • 1997
  • This study was performed to investigate the reproductibility of eccentric mandibular movements according to preferred chewing side, range of mouth opening, type of lateral guidance and involvement of temporomandibular disorders. 50 patients with temporomandibular disorders and 65 dental students without any signs and symptoms were randomly selected for this study as the patients group and the control group, respectively. For recording and observation of eccentric mandibular movement trajectory, BioEGN\textregistered of Biopak\textregistered system (Bioresearch Inc., USA) was used. Each eccentric movement to anterior, right and left side was performed three times similar to the movement pattern for Pantronic Reproducibility Index. mandibular path was analyzed by three dimensional positional change and the three paths from one direction were compared with one another. From this, reproducibility index of one-directional lateral movement could be calculated, and total reproducibility index, named BioEGN reproducibility index(BERI), was also computed from three-directional eccentric movement likewise. BioEGN reproducibility Index could have four value of score by small or large scale, and by outgoing or incoming movement. The data were analyzed by SAS/stat program and the results obtained were as follows: 1. Right side chewing subjects showed more consistent pattern In reproducibility index in comparison between patients group and control group than left chewing subjects have done, and reproducibility was low in patients group. However, there was no difference between the two stoups in bilateral chewing subjects. 2. There were no difference in reproducibility index between preferred chewing side and contralateral side in unilateral chewing subjects whereas reproducibility index in left side on outgoing movement were higher than in right side in bilateral chewing subjects. 3. Difference in total reproducibility index(BERI) between canine guidance group and non-canine guidance group were not observed though difference in reproducibility index on lateral movement were observed in part. 4. There were no difference in reproducibility index between affected side and contralateral side in unilaterally affected patients, and between unilaterally affected patients and bilaterally affected patients in patients group. 5. Highly significant positive correlationship were shown among the four 쇼pes of total reproducibility index(BERI) in total subjects, and range of clinical mouth opening was negatively correlated with BEBI on outgoing movements and with index on outgoing movement to preferred side.

  • PDF

Displacement-based Seismic Assessment and Rehabilitation of Asymmetric Wall Structures (비대칭 벽식 구조지 변위기초 내진성능평가 및 보강)

  • Hong, Sung-Gul;Ha, Tae-Hyu
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.9 no.3 s.43
    • /
    • pp.23-32
    • /
    • 2005
  • Torsional behavior of eccentric structure under seismic leading may cause the stress and/or deformation concentration, which arouse the failure of the structure in an unexpected manner. This study suggests D-R relationship which shows the overall displacement and rotation of the system based on the ultimate displacement capacity of the each lateral load resistant member. Using the suggested D-R relationship and displacement spectrum, the seismic assessment is conducted and verified in comparison with the time history analysis result. Multi-level seismic assessment Is considered which takes multiple seismic hazard levels and respective performance levels into account. Finally, based on the seismic assessment result, seismic rehabilitation process is presented. In this research, two rehabilitation methods are considered. One is done by means of stiffening/strengthening the seismic resistant members, and the other is based on the member ductility. Especially, in the first method, to optimize the rehabilitation result, the rehabilitation problem is modeled as an optimization problem, and solved using BFGS quasi-Newton optimization method.

p-Version Finite Element Model of Stiffened Plates by Hierarchic C0-Element (계층적 C0 - 요소에 의한 보강판의 p-Version 유한요소 모델)

  • 홍종현;우광성;신영식
    • Computational Structural Engineering
    • /
    • v.9 no.1
    • /
    • pp.33-45
    • /
    • 1996
  • A general stiffener element which includes transverse shear deformation is formulated using the p-version finite element method. Hierarchic C/sup o/-shape functions, derived from Integrals of Legendre polynomials, are used to define the assembled stiffness matrix of the stiffener with respect to the local reference frame is transformed to the plate reference system by applying the appropriate transformation matrices in order to insure compatibility of displacements at the junction of the stiffener and plate. The transformation matrices which account for the orientation and the eccentricity effects of the stiffener with respect to the plate reference axes are used to find local behavior at the junction of the stiffener and the relative contributions of the plate and stiffener to the strength of the composite system. The results obtained by the p-version finite element method are comared with the results in literatures, especially those by the h-version finite element analysis program, MICROFEAP-II.

  • PDF

Numerical Study on Interior Flat Plate-Column Connections Subjected to Unbalanced Moment (불균등 휨모멘트를 받는 플랫 플레이트-기둥 접합부에 대한 해석연구)

  • 최경규;황영현;박홍근
    • Journal of the Korea Concrete Institute
    • /
    • v.14 no.6
    • /
    • pp.949-960
    • /
    • 2002
  • Flat plate structures under lateral load are susceptible to punching shear failure of the slab-column connection. To prevent such brittle failure, strength and ductility of the connection should be ensured. However, due to complexity in the behavior and difficulty in simulating the actual load and boundary conditions of the flat plate system, it is not easy to obtain reliable data regarding to the strength and ductility from the previous experimental studies. In the present study, a numerical study was performed for interior connections of continuous flat plate. For the purpose, a computer program for nonlinear FE analyses was developed, and the validity was verified by comparisons with the existing experimental results. Through the parametric studies, the variations of bending moment, shear, and torsional moment around the connection were investigated. Based on the findings of the numerical studies, the aspects which need to be improved in current design methods were discussed. The results of the present study will be used for developing a design method for the flat plate-column connection in the companion paper.

Analysis of the Linear Transformation of Prestressing Tendon Using Equivalent toad Method (등가하중법 관점에서 분석한 프리스트레싱 텐던의 직선이동)

  • 오병환;전세진
    • Journal of the Korea Concrete Institute
    • /
    • v.14 no.6
    • /
    • pp.843-850
    • /
    • 2002
  • Linear transformation theory has been effectively used in the design and analysis of prestressed concrete structures. The underlying assumptions of the theory, which were often overlooked, are investigated in the respect of equivalent load method. As a result, it is found that the same equivalent loading system is produced for all the cases of the linear transformation by the assumptions of the conventional equivalent load method. On the other hand, equivalent loading systems in a strict and accurate sense do not satisfy the classical theories of the linear transformation. Also, it is shown that a little different equivalent loading system from the conventional one is obtained for each linear transformation according to the proposed equivalent load method that is derived from the self-equilibrium property of the tendon-induced forces. Therefore, it can be concluded that the linear transformation theory is valid only when referring to the conventional approximate equivalent load method. The discussions are further extended to the eccentrically located circumferential tendon in the wall of containment structures, where the problem of eccentricity is analyzed also from the view point of the linear transformation.

Adaptive Repetitive Control for an Eccentricity Compensation of Optical Disk Drive (광 디스크 드라이브의 편심 보상을 위한 적응 반복 제어)

  • Seo, Sam-Jun;Kim, Dong-Won;Park Gwi-Tae
    • Journal of the Korean Institute of Intelligent Systems
    • /
    • v.15 no.2
    • /
    • pp.135-142
    • /
    • 2005
  • This paper presents an adaptive repetitive control scheme for optical disk drives to track a variable periodic reference signal. Periodic disturbances can be adequately attenuated using the concept of repetitive control, provided the period is known. Because optical disk drives support various speeds, they have the varying periodic disturbances. Based on repetitive control to change sampling frequency to follow the change of reference period, an adaptive repetitive control is proposed in order to deal with such disturbances. The proposed control consists of the repetitive controller and the frequency generator. The former uses a varying sampler operating at fixed multiple times of the disturbance frequency and the latter generates the changeable sampling frequency based on the disturbance frequency. The experimental results on the control of an optical disk drive demonstrate the effectiveness of the proposed schemes and the improvement of random access time as well.

Inelastic Seismic Response of Asymmetric-Plan Self-Centering Energy Dissipative Braced Frames (비정형 셀프센터링 가새골조의 비탄성 지진응답)

  • Kim, Jin-Koo;Christopoulos, C.;Choi, Hyun-Hoon
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.12 no.4
    • /
    • pp.35-44
    • /
    • 2008
  • A self-centering energy-dissipative(SCED) bracing system has recently been developed as a new seismic force resistant bracing system. The advantage of the SCED brace system is that, unlike other comparable advanced bracing systems that dissipate energy such as the buckling restrained brace(BRB) system, it has a self-centering capability that reduces or eliminates residual building deformations after major seismic events. In order to investigate the effects of torsion on the SCED brace and BRB systems, nonlinear time history analyses were used to compare the responses of 3D model structures with three different amounts of frame eccentricity. The results of the analysis showed that the interstory drifts of SCED braced frames are more uniform than those of BRB frames, without regard to irregularity. The residual drift and residual rotation responses tended to decrease as irregularity increased. For medium-rise structures, the drift concentration factors(DCFs) for SCED systems were lower than those for BRB frames. This means that SCED-braced frames deform in a more uniform manner with respect to building height. The effect of the torsional irregularity on the magnitude of the DCFs was small.