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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 21, Issue 12 - Dec 1997
Volume 21, Issue 11 - Nov 1997
Volume 21, Issue 10 - Oct 1997
Volume 21, Issue 9 - Sep 1997
Volume 21, Issue 8 - Aug 1997
Volume 21, Issue 7 - Jul 1997
Volume 21, Issue 6 - Jun 1997
Volume 21, Issue 4 - Apr 1997
Volume 21, Issue 5 - Jan 1997
Volume 21, Issue 3 - Jan 1997
Volume 21, Issue 2 - Jan 1997
Volume 21, Issue 1 - Jan 1997
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A study on the linearity improvement of a vibrating gyroscope by output feedback
Park, Sung-Wook ; Oh, Jun-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1013~1020
DOI : 10.22634/KSME-A.19126.96.36.1993
Among various gyroscopes, the vibrating gyroscope has advantages such as compact size, mass-productivity and low cost. However this kind of gyroscope usually suffer from low linearity and low signal to noise ratio. Therefore, it is necessary to study on vibrating gyroscope to improve performance. In this paper, triangular cross section si selected in consideration for several points. The existing designs of exciting and sensing have some problems such that small signal size and low linearity. This paper proposes new design of exciting and sensing which is named one period exciting and the other period sensing. This design improves signal size, but it cannot improve linearity. This is because above two designs are the same open-loop type. So, another new design is proposed, which is named rebalancing, is applied to one period exciting and the other period sensing. This design are closed-loop type. It feedbacks the output signal. According to control theory, it can improve linearity. The circuits of each design are realized and used to calibration test. Calibration results show that new design of rebalancing improves linearity and signal size.
A review of ductile fracture criteria for forming processes
Park, Jong-Jin ; Lee, Young-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1021~1029
DOI : 10.22634/KSME-A.19188.8.131.521
In metalforming, ductile fracture criteria have been used for the purpose of predicting fracture occurrence in the stage of process design prior to manufacturing. In the present investigation, some of popular criteria are reviewed to find the most suitable one among them. As a result, it is found that the modified Cockroft and Latham criterion is better than others. The reasons are: it agrees with Roy's and McClintock's void growth models, it is more general than Oyane's and Kuhn's criteria, and it predicts fractures in compression as well as in tension well. However, it is also found that the criterion is incapable of predicting fractures in torsion.
A study on the adaptive method of control model for tandem cold rolling mill
Lee, Won-Ho ; Lee, Sang-Ryong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1030~1041
DOI : 10.22634/KSME-A.19184.108.40.2060
The control model in the tandem cold rolling mill consists of many mathematical theories and is used to calculate the reference values such as the roll gap and the rolling speed for good operation of rolling mill. But, the control model used presently has a problem causing inaccurate prediction of the rolling force. By the parameter identification, it was found that the main factor causing inaccurate prediction of the rolling force was incorrect modeling of the friction coefficient and the flow stress. To get rid of the erroneous factor new adaptive schemes are suggested in this work. Those are a long-time adaptation by the iterative least-square method and a short-time adaptation by the recursive weighted least-square method respectively. The new equations for the friction coefficient and the flow stress are derived by applying the suggested adaptive algorithms. Through the on-line test in an actual mill, it is proved that the rolling force predicted by the new equations is more accurate than the one by the existing equations ever used.
Finite element analysis of inelastic thermal stress and damage estimation of Y-structure in liquid metal fast breeder reactor
Kwak, Dae-Yeong ; Im, Yong-Taek ; Kim, Jong-Beom ; Lee, Hyeong-Yeon ; Yoo, Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1042~1049
DOI : 10.22634/KSME-A.19220.127.116.112
LMFBR(Liquid Metal Fast Breeder Reactor) vessel is operated under the high temperatures of 500-550.deg. C. Thus, transient thermal loads were severe enough to cause inelastic deformation due to creep-fatigue and plasticity. For reduction of such inelastic deformations, Y-piece structure in the form of a thermal sleeve is used in LMFBR vessel under repeated start-up, service and shut-down conditions. Therefore, a systematic method for inelastic analysis is needed for design of the Y-piece structure subjected to such loading conditions. In the present investigation, finite element analysis of heat transfer and inelastic thermal stress were carried out for the Y-piece structure in LMFBR vessel under service conditions. For such analysis, ABAQUS program was employed based on the elasto-plastic and Chaboche viscoplastic constitutive equations. Based on numerical data obtained from the analysis, creep-fatigue damage estimation according to ASME Code Case N-47 was made and compared to each other. Finally, it was found out that the numerical predictio of damage level due to creep based on Chaboche unified viscoplastic constitutive equation was relatively better compared to elasto-plastic constitutive formulation.
A study on the sheet bending by the plastic deformation of flange
Ho, Kwang-Il ; Chang, Yoon-Sang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1050~1057
DOI : 10.22634/KSME-A.1918.104.22.1680
The sheet bending with large radius of curvature is analyzed with both theoretical and experimental methods. Sheet bending in elastic limit is accomplished by the plastic deformation of flange. The springback model is developed theoretically and the effects of the factors are evaluated. The prediction accuracy of the model is also evaluated by comparing with the experimental data. Finally, an algorithm to design the sheet-bending die is suggested for usage in industry.
Development f head-neck complex dummy for experimental study
Kim, Yeong-Eun ; Nam, Dae-Hun ; Koh, Chang-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1058~1072
DOI : 10.22634/KSME-A.1922.214.171.1248
A head-neck complex dummy, for measuring brain pressure and reaction force in the cervical spine was developed for experimental study related in injury mechanism. Dummy comprised aluminium-casted head with water filled cavity for simulating brain and mechanical neck assembled with six motion segments. Several kinds of experiments (compression, bending, cyclic modulus, relaxation and constant velocity profile) for the developed mechanical neck showed that this neck model is biomechanically reliable compared with in-vitro test results. As an application of developed head-neck complex dummy, shock absorbing properties of protective helmet was chosen. The experiments showed that the maximum pressure increment of brain after impact was tolerable compared with the guide line for mild brain injury pressure (25psi). Constrast to this results, the reaction force in the neck was high enough to produce failure in the cervical spine.
Stage 1 compaction behavior of tool steel under die pressing
Kim, Gi-Tae ; Kim, Jong-Seong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1073~1080
DOI : 10.22634/KSME-A.19126.96.36.1993
The stage 1 compaction behavior of tool steel powder under die pressing was studied. The friction effects between the powder and the die wall under different die pressing modes were also investigated. The elastoplastic constitutive equations based on the yield functions by Fleck et al. and by Shima and Oyane were implemented into a finite element program to simulate die compaction processes. Finite element calculations were compared with experimental data for densification and density distribution of tool steel powder under single and double action die pressing. Finite element calculations using the yield function by Fleck et al. agreed better with experimental data than by Shima and Oyane.
A study on working limit of cold forging of carbon steel
Jae, Jin-Soo ; Kang, Jong-Hun ; Kang, Seong-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1081~1088
DOI : 10.22634/KSME-A.19188.8.131.521
The purpose of this work is to investigate the working limit of carbon steel and forging condition of cold forging. The fracture criteria which was proposed by Oyane and Osakada was used. Compression test, hardness study and tension test by Oyane's creteria, microstructure study by Osakada's were carried out. The results were compared with each other. It was found that working limit on compressive hydrostatic stress is increased in comparison with that of tensile stress field and can be forecasted the fracture limit of closed cold forging.
Integrity evaluation of Kori 1 reactor vessel for Rancho Seco transient
Jhung, M.J ; Park, Y.W ; Lee, J.B ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1089~1096
DOI : 10.22634/KSME-A.19184.108.40.2069
In this paper, Rancho Seco transient which is reported as a typical pressurized thermal shock event is postulated to be occuring in the Kori unit 1 plant, the oldest nuclear power plant in Korea. For the given material properties, transient history such as temperature and pressure, and postulated flaw, the stress distribution is obtained to calculate stress intensities for a wide range of assumed crack sizes. The stress intensities are compared with the fracture toughness, which is determined using the material properties and the distribution of the nil ductility transition temperature, to determine if cracking is expected to occur during the transient. The allowable operating year for the transient is determined and the evaluation results are discussed.
Variation of fatigue crack propagation behavior based on the shape of the interaction between two cracks
Song, Sam-Hong ; Choe, Byeong-Ho ; Bae, Jun-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1097~1105
DOI : 10.22634/KSME-A.19220.127.116.117
Because of the existence of stress interaction field made by other defects and propagating cracks, the structure may be weakened. Therefore in this study, the crack behavior in the interaction field made by two different cracks is studied experimentally. In the experiment, vertical distance between two cracks and applied stress are varied to make different stress interacted field. In addition, the effect of plastic zone is used to examine crack propagation path and rate. Three types of crack propagation in the interacted field were found, and crack propagating path and rate of two cracks were significantly changed according to different applied stress as each crack propagates. And the results are attributed to the effect of the size and shape of the plastic zone.
Input design to reduce residual vibration for a nonlinear time-varying system
Pang, Jeong-Hun ; Park, Youn-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1106~1115
DOI : 10.22634/KSME-A.1918.104.22.1686
A method of obtaining a control input to reduce residual vibration was developed for nonlinear time-varying systems moving along pre-determined two dimensional paths. First, the nonlinear system equation was solved with nominal input then linearized by nominal response which is defined at equilibrium point. Next an additional input can be obtained by solving the linearized equation that should satisfied the required boundary conditions. Residual vibration reduction was experimentally verified by applying the control input, which is sum of nominal and additional input, to a moving pendulum whose length is varying time.
Effect of friction between metal powder and a mandrel on densification during cold isostatic pressing
Lee, Hui-Tae ; Kim, Ki-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1116~1126
DOI : 10.22634/KSME-A.1922.214.171.1246
The effects of friction between powder and a mandrel on densification behavior of metal powder were investigated under cold isostatic pressing. The elastoplastic constitutive equations based on the yield function of Shima and Oyane were implemented into finite element program (ABAQUS) to simulate compaction responses of metal powders during cold isostatic pressing. The friction coefficients between powder and mandrels with different roughness were determined by comparing experimental data and finite element results. Density distributions in the powder compacts were also studied for different friction coefficients. Finite element results were compared with experimental data for pure iron powder under cold isostatic pressing.
The Identification of Generation Mechanism of Noise and Vibrtaion and Transmission Characteristics for Engine System - The Source Identification and Noise Reduction of Compartment by Multidimensional Spectral Analysis and Vector Synthesis Method -
O, Jae-Eung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1127~1140
DOI : 10.22634/KSME-A.19126.96.36.1997
With the study for identifying the transmission characteristics of vibration and noise generated by operating engine system of a vehicle, recently many engineers have studied actively the reduction of vibration and noise inducing uncomfortableness to the passenger. In this study, output noise was analyzed by multi-dimensional spectral analysis and vector synthesis method. The multi-dimensional analysis method is very effective in case of identification of primary source, but this method has little effect on suggestion for interior noised reduction. For compensation of this, vector synthesis method was used to obtain effective method for interior noise reduction, after identifying primary source for output noise. In this paper, partial coherence function of each input was calculated to know which input was most coherent to output noise, then with simulation of changes for input magnitude and phase by vector synthesis diagram, the trends of synthesized output vector was obtained. As a result, the change of synthesized output vector could be estimated.
Optimum design of blank shape for press forming
Kim, Yeong-Seok ; Park, Gi-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1141~1148
DOI : 10.22634/KSME-A.19188.8.131.521
In the stamping industry the blank shape to be stamped into a designed shape has been conventionally determined from the try out process by the press engineers. The work needs a lot of time and thus leads a loss of productivity. In this study boundary element method for 2-dimensional potential problem was used to design optimum blank shapes for irregular press forming. Here we assumed that the blank is controlled by blank holder only and material flow at blank holder was under potential flow. The developed PC code for designing the optimum blank shape shows that the blank shapes for optimal drawing can be calculated within a few minute in pentium PC and the calculated shapes agree well with the experiments. However the application of this method is constrained only to the pressed product with flat bottom.
J-integral for subsurface crack in circular plate with inner hole under rolling and sliding contact
Lee, Kang-Yong ; Kim, June-Yeop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1149~1155
DOI : 10.22634/KSME-A.19184.108.40.2069
J-integral for a subsurface horizontal crack in a circular plate with an inner hole under rolling line contact is evaluated according to loading positions with various load conditions, crack length and crack location. Two-dimensional crack is modeled, and the relation between Tresca stress for uncracked model and J-integral is discussed. The loading location which gives the maximum J-integral depends on load condition and crack location, and the presence of friction force increases Tresca stress and J-integral near the surface. Regardless of friction force, crack location that gives maximum J-integral is the same as that of maximum Tresca stress in an uncracked model, and the value of J-integral is propotional to crack length. It is also showed that the variation of an inner radius of a disk does not effect J-integral value.
In-situ modal testing and parameter identification of active magnetic bearing system by magnetic force measurement and the use of directional frequency response functions
Ha, Young-Ho ; Lee, Chong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1156~1165
DOI : 10.22634/KSME-A.19220.127.116.116
Complex modal testing is employed for the in-situ parameter identification of a four-axis active magnetic bearing system while the system is in operation. In the test, magnetic bearings are used as exciters as well as actuators for feedback control. The experimental results show that the directional frequency response function, which is properly defined in the complex domain, is a powerful tool for identification of bearing as well as modal parameters. It is also shown that the position and current stiffnesses can be accurately estimated using the relations between the measured forces, displacements, and currents.
Development of harmonic drive using cycloide tooth profile
Lee, Chong-Won ; Oh, Se-Hoon ; Kim, Jun-Cheol ; Jeon, Han-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 7, 1997, Pages 1166~1173
DOI : 10.22634/KSME-A.1918.104.22.1686
Due to progress in manufacturing techniques, the performance of the harmonic drive has been improved but not sufficiently. One of the important problems which the current harmonic drive has is that while there is the potential for having a wider tooth contact area, the total number of teeth engaged simultaneously is still small. This is mainly due to the involute tooth profile. Hence, in this study, the cycloid-type tooth profile is developed to improve this problem. This paper represents the design methodology and performance evaluation f the cycloid-type harmonic drive. Cycloide tooth profile was derived by analyzing geometry of the tooth engagement and the contact mechanisms of the tooth which were examined and analyzed by load analysis. The stress due to elastic deformation of a flexspline was also obtained by approximate formula and computer analysis. Finally, the cycloid-type harmonic drive with 1:100 speed ratio was manufactured and the performance of the harmonic drive was evaluated.