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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 35, Issue 12 - Dec 2011
Volume 35, Issue 11 - Nov 2011
Volume 35, Issue 10 - Oct 2011
Volume 35, Issue 9 - Sep 2011
Volume 35, Issue 8 - Aug 2011
Volume 35, Issue 7 - Jul 2011
Volume 35, Issue 6 - Jun 2011
Volume 35, Issue 5 - May 2011
Volume 35, Issue 4 - Apr 2011
Volume 35, Issue 3 - Mar 2011
Volume 35, Issue 2 - Feb 2011
Volume 35, Issue 1 - Jan 2011
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Ride Comfort Analysis of High-Speed Train with Flexible Car Bodies
Shin, Bum-Sik ; Choi, Yeon-Sun ; Koo, Ja-Choon ; Lee, Sang-Won ; Lee, Sung-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 341~346
DOI : 10.3795/KSME-A.2011.35.4.341
In the development of high-speed trains, ride comfort is an important factor that determines the quality of the train. In this study, the ride comforts of high-speed trains with rigid and flexible car bodies were evaluated. The rail irregularity is used as an exciting source of the car-body bounce motion. The complex extruded structures of the car-body are modeled as shell structures using the calculated equivalent stiffness of the flexible model. The numerical results show that the ride of the rigid-body model improves as the speed increases, which is unreasonable. In contrast, the relationship between ride comfort and speed in the case of flexible-body model is reasonable. Thus, it is confirmed that the flexibility of the car body needs to be taken into consideration while fabricating a high-speed train.
Impedance-Control Based Peg-in-Hole Assembly with a 6 DOF Manipulator
Kim, Byeong-Sang ; Kim, Young-Loul ; Song, Jae-Bok ; Son, Seung-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 347~352
DOI : 10.3795/KSME-A.2011.35.4.347
The maximum accuracy of position control by using an industrial robot is about
, whereas the maximum tolerated imprecision in the position of precision parts is about several tens of micrometers. Therefore, it is very difficult to assemble parts by position control only. Moreover, in the case of precision assembly, jamming or wedging can easily occur because of small position/orientation errors, which may damage the parts to be assembled. To overcome these problems, we investigated a force control scheme that provides proper motion in response to the contact force. In this study, we constructed a force control system that can be easily implemented in a position-controlled manipulator. Impedance control by using an admittance filter was adopted to perform stable contact tasks. It is shown that the precision parts can be assembled well by adopting impedance control and blind search methods.
Optimal Design of Permanent Magnet Thrust Bearings
Yoo, Seong-Yeol ; Kim, Woo-Yeon ; Kim, Seung-Jong ; Lee, Wook-Ryun ; Bae, Yong-Chae ; Noh, Myoung-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 353~358
DOI : 10.3795/KSME-A.2011.35.4.353
In this paper, we describe a process for optimally designing a ring-type permanent magnet thrust bearing. The bearing consists of two sets of permanent magnet rings. One set is located inside the other set. An axial offset between the two sets creates axial force, which results in a thrust bearing function. In order to realize an optimal design of the bearing where the required load capacity of the bearing is achieved with the least magnet volume, we derived analytical design equations by adopting the equivalent current sheet (ECS) method. We considered the following two types of magnet arrays: axial arrays and Halbach arrays. These two types of arrays are optimized using the analytical design equations. The results of the optimization are verified using three dimensional (3D) finite element analyses (FEA). The results show that the Halbach array can achieve the required load capacity with less amount of permanent magnet than the axial array does. The efficacy of the ECS method is also verified by using 3D FEA. It is found that the accuracy of ECS method is more sensitive to the underlying assumptions for the Halbach array than for the axial array.
Experimental Verification of Effectiveness of Stabilization Control System for Mobile Surveillance Robot
Kim, Sung-Soo ; Lee, Dong-Youm ; Kwon, Jeong-Joo ; Park, Sung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 359~365
DOI : 10.3795/KSME-A.2011.35.4.359
A mobile surveillance robot is defined as a surveillance robot system that is mounted on a mobile platform and is used to protect public areas such as airports or harbors from invaders. The mobile surveillance robot that is mounted on a mobile platform consists of a gun module, a camera system module, an embedded control system, and AHRS (Attitude and Heading Reference System). It has two axis control systems for controlling its elevation and azimuth. In order to obtain stable images for targeting invaders, this system requires a stabilizer to compensate any disturbance due to vehicle motion. In this study, a virtual model of a mobile surveillance robot has been created and ADAMS/Matlab simulations have been performed to verify the suitability of the proposed stabilization algorithm. Further, the suitability of the stabilization algorithm has also been verified using a mock-up of the mobile surveillance robot and a 6-DOF (Degree Of Freedom) motion simulator.
Study on Designing Recoil System with Friction Springs
Kim, Young-Seon ; Kim, Sung-Soo ; Cha, Ki-Up ; Noh, Myoung-Gyu D. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 367~374
DOI : 10.3795/KSME-A.2011.35.4.367
Friction springs have different characteristics while loading and un-loading. Because of these characteristics, they are utilized in impact systems. In this paper, the design of a recoil system with friction springs for use in a machine gun system has been presented. In order to determine the stiffness of a friction spring, equations of motion for a simple gun model with a recoil system have been derived. The impulse balance scheme has been adopted. On the basis of simulation results, the diameter of the friction spring has been determined.
Probabilistic Characteristics of Fatigue Behavior Parameter of Paris-Erdogan Law in Mg-Al-Zn Alloy
Choi, Seon-Soon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 375~381
DOI : 10.3795/KSME-A.2011.35.4.375
The primary aim of this study is to investigate the probabilistic characteristics of the fatigue parameters that describe the fatigue crack growth behavior in magnesium alloy. Statistical fatigue crack propagation experiments have been performed on rolled AZ31 magnesium alloy CT specimens with different specimen thickness, load ratio, and maximum load at ambient temperature in a laboratory. Using the statistical fatigue data obtained from these experiments, the goodness-of-fit of the probability distribution of the fatigue behavior parameters is evaluated in this study by performing statistical analyses. The crack growth rate coefficient is a fatigue parameter having a very large COV(Coefficient of Variation), but the variation of a crack growth rate exponent is not substantial. It is considered that a crack growth rate exponent can be a material constant. It is also found that the best fit probability distribution of the parameters such as the crack growth rate coefficient and crack growth rate exponent for a magnesium alloy is a three-parameter Weibull distribution, and two-parameter Weibull distribution is a good distribution only for the crack growth rate coefficient.
A Study on Spot-Welding Characteristics and Material Analysis of Boron Steel for Hot-Stamping under Different Heat-Treatment Conditions
Je, Hwan-Il ; Son, Chang-Suk ; Nam, Ki-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 383~391
DOI : 10.3795/KSME-A.2011.35.4.383
The hot-stamping technique is used to manufacture high-strength parts by press forming by heating at a temperature above the Austenite transformation temperature and then rapid cooling. Boron steel, which contains a very small amount of boron, is one of the materials used for hot stamping. The purpose of this study is to show the microstructures and to investigate the mechanical properties under different heat-treatment conditions. The heat treatment of water quenching was conducted at the various temperatures and different elapsed times. These can be practical data useful when boron steels are used for hot stamping. Furthermore, the microstructures and mechanical properties of the spot-welded specimen with coatings and counterpart materials (SPRC 340, SPRC 590) is investigated in order to determine the welding characteristics of boron steel at different welding condition.
Inverse Estimation of Fatigue Life Parameters of Springs Based on the Bayesian Approach
Heo, Chan-Young ; An, Da-Wn ; Won, Jun-Ho ; Choi, Joo-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 393~400
DOI : 10.3795/KSME-A.2011.35.4.393
In this study, a procedure for the inverse estimation of the fatigue life parameters of springs which utilize the field fatigue life test data is proposed to replace real test with the FEA on fatigue life prediction. The Bayesian approach is employed, in which the posterior distributions of the parameters are determined conditional on the accumulated life data that are routinely obtained from the regular tests. In order to obtain the accurate samples from the distributions, the Markov chain Monte Carlo (MCMC) technique is employed. The distributions of the parameters are used in the FEA for predicting the fatigue life in the form of a predictive interval. The results show that the actual fatigue life data are found well within the posterior predictive distributions.
Development of Prediction Model and Parameter Optimization for Second-Generation Magnetic Abrasive Polishing of Magnesium Alloy
Kim, Sang-Oh ; Lee, Sung-Ho ; Kwak, Jae-Seob ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 401~407
DOI : 10.3795/KSME-A.2011.35.4.401
The conventional method of magnetic abrasive polishing is not suitable for non-magnetic materials because such polishing is basically possible when magnetic force exists and the magnetic force in non-magnetic materials is very low. The installation of an electromagnet under the working area of a non-magnetic material, which is called second-generation magnetic abrasive polishing in this study, can enhance the magnetic force. Experimental evaluation and optimization of process parameters for polishing magnesium alloy steel was performed by adopting the design of experiments and the response surface method. The results indicated that the intensity of the magnetic force and spindle speed are significant parameters that affect the improvement of surface roughness. A prediction model for the surface roughness of the magnesium alloy steel is developed using the second-order response surface method.
Vibration Characteristic Analysis of Gimbal Structure System with Observation Reconnaissance Camera Module
Lee, Sang-Eun ; Lee, Tae-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 409~415
DOI : 10.3795/KSME-A.2011.35.4.409
A gimbal system in observation reconnaissance aircraft was fabricated by assembling many parts and bearings. This system consists of a camera module and a stabilization gimbal that supports the camera module. During the flight for recording images, the gimbal system experiences various accelerations with wide frequencies. Although base excitation of stabilization gimbal results in vibration of the camera module, the camera module must be able to capture the correct and clear image even while vibrating. Hence, it is important to know the natural frequencies and vibration modes of the gimbal system with the camera module. Considering bearings as spring elements, the vibration characteristic of the gimbal system was analyzed by finite element method. In addition, harmonic response analysis was performed to determine the correct transmissibility of acceleration for the camera module in the frequency range of 0-500 Hz.
Mechanical Performance Evaluation of a Top End Piece for Dual Cooled Fuels
Kim, Jae-Yong ; Yoon, Kyung-Ho ; Kim, Hyung-Kyu ; Choi, Woo-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 417~424
DOI : 10.3795/KSME-A.2011.35.4.417
A fuel assembly consists of five major components, i.e., a top end piece (TEP), a bottom end piece (BEP), spacer grids (SGs), guide tubes (GTs) and an instrumentation tube (IT); in addition, it also includes fuel rods (FRs). The TEP/BEP should satisfy stress intensity limits according to the conditions A and B of ASME, Section III, Division 1-Subsection NB. In a dual-cooled fuel assembly, the array and position of fuel rods are different from those in a conventional PWR fuel assembly; these changes are necessary for achieving power uprating. The flow plates of the TEP and BEP have to be modified accordingly. The pattern and shape of the flow holes were newly designed. To verify the strength compatibility, the Tresca stress limit according to the ASME code was investigated in the case of an axial load of 22.241 kN. In this paper, the stress linearization procedure for strength evaluation of a newly designed TEP is presented.
Analysis of Hot Judder of Disc Brakes for Automotives by Using Finite Element Method
Jung, Sung-Pil ; Park, Tae-Won ; Chung, Won-Sun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 425~431
DOI : 10.3795/KSME-A.2011.35.4.425
Thermal energy generated because of the friction between the disc and pad is transferred to both sides and causes thermal expansion of the material, which affects the contact pressure distribution. This phenomenon, which is called thermoelastic instability (TEI), is affected by the natural mode of a disc. TEI results in the formation of a hot spot and causes hot judder vibrations. In this study, three-dimensional analysis of the hot judder of a ventilated disc for automotives was performed by using the commercial finite element analysis program, SAMCEF. The intermediate processor based on a staggered approach was used to exchange the result data of the mechanical and thermal model. The hot spot was formed on the surface of the disc, and the number of hot spots was compared with the natural mode of the disc.
Development of Program for Designing Barrel Cam of Machine Making Paper Cups
Kim, Wook-Hyeon ; Park, Tae-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 433~438
DOI : 10.3795/KSME-A.2011.35.4.433
A machine that makes paper cups has many parts, including a barrel cam, an index, and a turret. When the barrel cam, which is the main operating part of the machine, rotates, it pushes the roller fixed on the index, and paper cups are formed as the turret connected to the index rotates. Therefore, the performance of the machine is affected by the barrel cam. In this study, the program for designing barrel cam, which creates the profile of the cam is developed using MATLAB. This profile is used to develop a 3D CAD model by using a 3D CAD program. Dynamic models containing the barrel cam are created on the basis of the profile and 3D laser scan of the barrel cam. Further, the rotation angle of the index in the machine is measured using a high-speed camera. The rotation angles of the dynamics models are compared to verify the effectiveness of the program.
Forensic Engineering Study on Assessment of Damage to Pressure Vessel Because of CNG Vehicle Explosion
Kim, Eui-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 439~445
DOI : 10.3795/KSME-A.2011.35.4.439
Forensic Engineering is the art and science of professionals qualified to serve as engineering experts in courts of law or in arbitration proceedings. Buses using compressed natural gas (CNG) trend to be extended in use internationally as optimal counterplan for reducing discharge gas of light oil due to high concern about environment. However, CNG buses have to be equipped with composite pressure vessels (CPVs); since the CPVs contain compressed natural gas, the risks in the case of accident is very high. Hence, the investigation of such accidents is usually associated with engineering analysis. Among the possible reasons for such CNG explosion accidents is vehicle fire and vessel fracture. By conducting formal inspection and engineering tests, in this study, the cause of vessel explosion is investigated by analyzing the failure mechanism by fractography and by comparing the material properties of a reference part with those of a problem part by adopting instrumented indentation technique.
Study on Creep Damage Model of 1Cr1Mo1/4V Steel for Turbine Rotor
Choi, Woo-Sung ; Fleury, Eric ; Song, Gee-Wook ; Kim, Bum-Shin ; Chang, Sung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 4, 2011, Pages 447~452
DOI : 10.3795/KSME-A.2011.35.4.447
It is well known that the dominant damage mechanisms in high-temperature steam turbine facilities such as rotor and casing are creep and fatigue damages. Even though coupling of creep and fatigue should be considered while predicting the life of turbine facilities, the remaining life of large steam turbine facilities is generally determined on the basis of creep damage because the turbines must generate stable base-load power and because they are operated at a high temperature and pressure for a long time. Almost every large steam turbine in Korea has been operated for more than 20 years and is made of steel containing various amounts of principal alloying elements nickel, chromium, molybdenum, and vanadium. In this study, creep damage model of 1Cr1Mo1/4V steel for turbine rotor is proposed and that can assess the high temperature creep life of large steam turbine facilities is proposed.