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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 37, Issue 12 - Dec 2013
Volume 37, Issue 11 - Nov 2013
Volume 37, Issue 10 - Oct 2013
Volume 37, Issue 9 - Sep 2013
Volume 37, Issue 8 - Aug 2013
Volume 37, Issue 7 - Jul 2013
Volume 37, Issue 6 - Jun 2013
Volume 37, Issue 5 - May 2013
Volume 37, Issue 4 - Apr 2013
Volume 37, Issue 3 - Mar 2013
Volume 37, Issue 2 - Feb 2013
Volume 37, Issue 1 - Jan 2013
Selecting the target year
Shape Monitoring of Composite Cantilever Beam by Using Fiber Bragg Grating Sensors
Lee, Kun-Ho ; Kim, Dae-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 833~839
DOI : 10.3795/KSME-A.2013.37.7.833
In this study, an experiment was performed to monitor the two-dimensional shape of a cantilever composite structure using fiber Bragg grating (FBG) sensors. To monitor the shape of a composite structure, a deflection equation developed by NASA was applied and a composite beam attached to three FBG sensors was used. In the experiment, the shape of the composite beam was successfully estimated and an error was evaluated by comparing a real deflection. The error increased with real deflection; therefore, it was compensated by using the linear relationship between the error and the real deflection. After compensating the error, the measured deflection shows good agreement with the real deflection. Finally, the experiment shows that the FBG sensor and the deflection equation are suitable for monitoring the deflection curve of the beam structure with compensation of the error.
Enhancement of Dimple Formability in Sheet Metals by 2-Step Forming
Kim, Hasung ; Kim, Minsoo ; Lee, Hyungyil ; Kim, Naksoo ; Kim, Dongchoul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 841~849
DOI : 10.3795/KSME-A.2013.37.7.841
In this study, a 2-step stamping model with an additional 1st stamping tool is proposed to reduce stamping flaws in the curved parts of a dimple in a nuclear fuel spacer grid. First, the strains of curved part of dimple are characterized via a comparison with strain solutions in pure bending. A reference 2D finite element (FE) model of 1-step stamping is then established, and the corresponding maximum strain is obtained. By varying the values of design variables of the 1st stamping tool in the 2-step stamping model, FE solutions are obtained to express the strain as a function of process variables, which provides the optimum values of process variables. Finally, applying these optimum values to a 3D FE model, we demonstrate the enhanced formability of the proposed 2-step stamping model.
Stabilization System for Mobile Antenna Gimbal based on Dynamic Characteristics Analysis
Lee, Ki-Nam ; Lee, Byoung-Ho ; Lee, Jeung ; Kim, Jie-Eok ; Song, Jae-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 851~856
DOI : 10.3795/KSME-A.2013.37.7.851
Recently, as the tactical environment has changedto one of network-centric warfare, where all components are connected through a network, much emphasis has been placed on the use of an artificial satellite for achieving high communication speeds. To provide a high-quality artificial satellite link, stabilization is very important in a platform. Previous stabilization control techniques used PI control, which is commonly used for vessels. However, for ground terminals that require a higher communication speed, the antenna should move faster to track an artificial satellite within a short period of time. Moreover, the terminals must be equipped with proper sensors and algorithms so that they can detect and compensate for external disturbances while tracking the artificial satellite. In this study, through the analysis of the dynamic model of an antenna system, a stabilization algorithm for ground terminals was proposed;this algorithm shows high isolation performance in the low-frequency range and includes
Stress Modeling of the Laser Drilling Process in Carbon Steel
Lee, Wooram ; Kim, Joohan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 857~864
DOI : 10.3795/KSME-A.2013.37.7.857
A laser machining process has been applied in many manufacturing fields and it provides an excellent energy control for treating materials. However, a heat effect during laser machining can deteriorate material properties. Specifically, a thermally induced stress can be a problem in laser-machined structures on a metal surface. In this study, temperature and stress on cold-rolled carbon steel sheet machined with laser hole drilling were explored in an experimental approach and a numerical method. Stresses by temperature gradients inside the materials were generated in fast cooling. The stresses were measured by using a hole-drilling method and the material properties of carbon steel (SCP1-S) were obtained in the experiment. It was found that the stress predicted from the numerical analysis was in agreement with the stresses measured by using the hole-drilling method. The analysis can be applied for evaluating structure characteristics machined with a laser.
Optimal Process Planning of CNG Pressure Vessel by Ensuring Reliability and Improving Die Life
Bae, Jun Ho ; Lee, Hyun Woo ; Kim, Moon Saeng ; Kim, Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 865~873
DOI : 10.3795/KSME-A.2013.37.7.865
The deep drawing and ironing (DDI) process involving the use of a high-capacity horizontal press is used for manufacturing acompressed natural gas (CNG) pressure vessel. However, some variables of the DDI process have been determined based on the experiences of workers, and the short die life needs to be improved for manufacturing the pressure vessel withhighquality and lowcost. In this study, process variables such as the draw ratio, distance between dies, radius of rounding of drawing die, and angle of ironing die are chosen to enhance the reliability and improve the die life based on previous studies and experiences. The draw ratio limits at which no tearing or wrinkling occurs are determined using FEA, and the distances between dies, radius of rounding of drawing die, and angle of ironing die are optimized by the DOE method. The results of the optimal process variables are compared with those of the existing DDI process for verifying their effectiveness.
Structural Integrity Assessment of High-Strength Anchor Bolt in Nuclear Power Plant based on Fracture Mechanics Concept
Lim, Eun-Mo ; Huh, Nam-Su ; Shim, Hee-Jin ; Oh, Chang-Kyun ; Kim, Hyun-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 875~881
DOI : 10.3795/KSME-A.2013.37.7.875
The failure of a bolted joint owing to stress corrosion cracking (SCC) has been considered one of the most important structural integrity issues in a nuclear power plant. In this study, the failure possibility of bolting, which is used to support the steam generator of a pressurized water reactor, owing to SCC and brittle fracture was evaluated in accordance with guidelines proposed by the Electric Power Research Institute, which are called the Reference Flaw Factor method. For this evaluation, first, detailed finite element stress analyses were conducted to obtain the actual nominal stresses of bolting in which either service loads or bolt preloads were considered. Based on these nominal stresses, the structural integrity of bolting was addressed from the viewpoints of SCC and toughness. In addition, the accuracy of the EPRI Reference Flaw Factor for assessing bolting failure was investigated using finite element fracture mechanics analyses.
Comparative Study of Reliability Analysis Methods for Discrete Bimodal Information
Lim, Woochul ; Jang, Junyong ; Lee, Tae Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 883~889
DOI : 10.3795/KSME-A.2013.37.7.883
The distribution of a response usually depends on the distribution of a variable. When the distribution of a variable has two different modes, the response also follows a distribution with two different modes. In most reliability analysis methods, the number of modes is irrelevant, but not the type of distribution. However, in actual problems, because information is often provided with two or more modes, it is important to estimate the distributions with two or more modes. Recently, some reliability analysis methods have been suggested for bimodal distributions. In this paper, we review some methods such as the Akaike information criterion (AIC) and maximum entropy principle (MEP) and compare them with the Monte Carlo simulation (MCS) using mathematical examples with two different modes.
Analysis of Compressive Deformation Behaviors of Aluminum Alloy Using a Split Hopkinson Pressure Bar Test with an Acoustic Emission Technique
Kim, Jong-Tak ; Woo, Sung-Choong ; Sakong, Jae ; Kim, Jin-Young ; Kim, Tae-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 891~897
DOI : 10.3795/KSME-A.2013.37.7.891
In this study, the compressive deformation behaviors of aluminum alloy under high strain rates were investigated by means of a SHPB test. An acoustic emission (AE) technique was also employed to monitor the signals detected from the deformation during the entire impact by using an AE sensor connected to the specimen with a waveguide in real time. AE signals were analyzed in terms of AE amplitude, AE energy and peak frequency. The impacted specimen surface and side area were observed after the test to identify the particular features in the AE signal corresponding to the specific types of damage mechanisms. As the strain increased, the AE amplitude and AE energy increased whereas the AE peak frequency decreased. It was elucidated that each AE signal was closely associated with the specific damage mechanism in the material.
Implementation of Levitation Controller for Toroidally-Wound Self-Bearing BLDC Motor Using Continuously Invertible Force Model
Choi, Won-Yeong ; Choi, Jung-Kyu ; Noh, Myounggyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 899~903
DOI : 10.3795/KSME-A.2013.37.7.899
A self-bearing is an electric machine that achieves both rotational actuation and magnetic levitation using a single magnetic structure. To be able to stably levitate the rotor in a self-bearing, one needs to have an inverse of the force-current model. However, the force-current model in a self-bearing motor is typically not square. Furthermore, the elements of the matrix vary with respect to the rotational angle, resulting in singularities of the pseudo-inverse at various angles. In this paper, we propose a new force-current model that eliminates the singularities by adding a constraint in coil currents. This constraint eliminates the flux density in the stator core so that the saturation problem in the previous study is avoided. By implementing this force-current model, we are able to implement a levitation controller for a toroidally-wound self-bearing BLDC motor. The model inversion and levitation are validated experimentally.
Study on Friction Energy of Rubber Block Under Vertical Load and Horizontal Velocity
Kim, Jin Kyu ; Yoo, Sai Rom ; Lee, Il Yong ; Kim, Doo Man ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 905~912
DOI : 10.3795/KSME-A.2013.37.7.905
Rubber is one of the most commonly used materials in various fields because of its unique viscoelastic properties. Friction occurs when a tire constantly makes contact with the ground. As a result, friction causes wear. The frictional energy caused by friction is a primary factor in the wear mechanism. The frictional energy is affected by various conditions (temperature, roughness of ground, shape of rubber, load, and materials). In this study, the analysis was preceded by considering the vertical load and the horizontal velocity to the rubber using ABAQUS/explicit. The contact pressure, and friction energy are derived using the shear force and slip distance. The actual behavior of the rubber test data were compared with the analysis results.
Variation of Material Characteristics of a Hot-formed AZ31 Magnesium Alloy
Suh, Chang-Min ; Hor, Kwang-Ho ; Kim, Hyo-Min ; Suh, Min-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 913~919
DOI : 10.3795/KSME-A.2013.37.7.913
Magnesium alloys are known to be hard-forming materials at room temperature owing to their material structure. This study analyzes the optimal temperature conditions of warm-forming and the forming process by using a high-pressure laminating test and FM analysis, respectively. The effect of temperature on the fatigue limit was examined from the collected specimens by analyzing the material properties after the fatigue test. The material formed at a temperature of
shows occasional defects, but the best forming quality was obtained at
. The optimal temperature for the forming process was found to be
considering the material quality and thermal efficiency. The overall fatigue life of specimens decreases with an increase in the processing temperature. The fatigue limit of AZ31 formed at
was approximately 100 MPa after
Performance Prediction of Landing Gear Considering Uncertain Operating Parameters
Kim, Tae Uk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 921~927
DOI : 10.3795/KSME-A.2013.37.7.921
The performance estimation of a landing gear with uncertain parameters is presented. In actual use, many parameters can have certain degrees of variations that affect the energy absorbing performance. For example, the shock strut gas pressure, oil volume, tire pressure, and temperature can deviate from their nominal values. The objective function in this study is the ground reaction during touchdown, which is a function of the abovementioned parameters and time. To consider the uncertain properties, convex modeling and interval analysis are used to calculatethe objective function. The numerical results show that the ground reaction characteristics are quite different from those of the deterministic method. The peak load, which affects the efficiency and structural integrity, is increases considerably when the uncertainties are considered. Therefore, it is important to consider the uncertainties, and the proposed methodology can serve as an efficient method to estimate the effect of such uncertainties.
A Study of Impact Reduction Characteristics of Hat-Shaped Stiffened Panel Under Hypervelocity Impact
Yang, Tae-Ho ; Lee, Young-Shin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 929~935
DOI : 10.3795/KSME-A.2013.37.7.929
This paper presents the results of sizing optimization of ahat-shaped stiffener on a rectangular stiffened panel. The stiffened panel is subjected to impact loading by a projectile with a velocity of 1500-2500 m/s. To determine the size of the hat-shaped stiffener, sizing optimization was performed. The sizing optimization consists of three functions: objective, constraint, and design functions. The objective function is used to maximize the fundamental frequency of the stiffened panel. The constraint function is that the stiffener volume is less than 10% of the plate volume. The design function is the dimensions of the hat-shaped stiffener. By using the stiffened panel with the optimized hat-shaped stiffener, a hypervelocity impact was simulated, and the velocity and kinetic energy on the optimized stiffener was obtained. To evaluate the impact reduction on the stiffened panel, the velocity and kinetic energy of the projectile was normalized and compared.
Study of Driving Stability Performance of 2-Wheeled Independently Driven Vehicle Using Electric Corner Module
Park, Jinhyun ; Choi, Jeonghun ; Song, Hyeonwoo ; Hwang, Sung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 937~943
DOI : 10.3795/KSME-A.2013.37.7.937
An independently driven electric corner module cannot be applied to an actual vehicle without some difficulty, because of vehicle safety problems in the case of malfunctions and degraded ride and handling performance owing to the increase in the unsprung mass. In this study, a simulator is developed to evaluate the vehicle driving performance in order to solve ride and handling problems. Component modeling of a small-sized electric vehicle with an independently driven electric corner module is performed using MATLAB/Simulink. The vehicle is modeled by using CarSim, which can be used to analyze the vehicle maneuvers with 27 DOFs. The control algorithm for the improvement of vehicle driving safety and ride and handling performance is validated by using the developed simulator.
Fatigue Strength Evaluation of Bogie Frame of Urban Maglev Train
Han, Jeong Woo ; Kim, Heung Sub ; Bang, Je Sung ; Song, See Yeob ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 7, 2013, Pages 945~951
DOI : 10.3795/KSME-A.2013.37.7.945
This study evaluated the fatigue strength of the bogie frame of an urban maglev train through fatigue analysis, cumulative damage, and fatigue tests based on a proposed fatigue evaluation method. The results of FEM analysis in which various load combinations were adopted showed that all data were under the fatigue limit of a butt welded joint made of A6005 in a Goodman diagram. The cumulative fatigue damage was calculated at the highest level from a bolt connecting the area of the electromagnetic pole in the casting block; however, the total sum was evaluated as D=0.808 based on
cycles, which indicates that it did not exceed the failure criteria. In addition, the results of the fatigue testshowed that there was no crack at any position in the bogie frame, which corresponded to the results of fatigue analyses.