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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
Journal Basic Information
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
Prognostic Technique for Ball Bearing Damage
Lee, Do Hwan ; Kim, Yang Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1315~1321
DOI : 10.3795/KSME-A.2013.37.11.1315
This study presents a prognostic technique for the damage state of a ball bearing. A stochastic bearing fatigue defect-propagation model is applied to estimate the damage progression rate. The damage state and the time to failure are computed by using RMS data from noisy acceleration signals. The parameters of the stochastic defect-propagation model are identified by conducting a series of run-to-failure tests for ball bearings. A regularized particle filter is applied to predict the damage progression rate and update the degradation state based on the acceleration RMS data. The future damage state is predicted based on the most recently measured data and the previously predicted damage state. The developed method was validated by comparing the prognostic results and the test data.
Endurance Life of Taper Roller Bearing for Wheel Loader Axles
Yoo, Dae Won ; Lee, Jai Hak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1323~1330
DOI : 10.3795/KSME-A.2013.37.11.1323
A wheel loader is a type of construction machinery that is capable of performing a variety of tasks, and demands on its functional diversity and structural reliability are growing. A wheel bearing is one of the core components that determine the life of the loader; taper roller bearings are commonly used for this purpose. The lifetime of a bearing is typically calculated based only on its load and revolution speed. The initial preload of a taper roller bearing is a critical factor that directly affects its endurance life. In this study, the relations between the endurance life and preload characteristics including the amount of preload according to the weight, rotational speed, and thermal modification applied to tapered roller bearings are presented. When the temperature is
, an excessive preload condition is expected compared with that at room temperature, and the durable life decreases by 20.3 %.
Structural Optimization for Hybrid Vertical-Axis Wind Turbine Blade using Response Surface Method
So, Ki-Sung ; Choi, Chan-Woong ; Lee, Dong-Chul ; Kang, Ki-Weon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1331~1337
DOI : 10.3795/KSME-A.2013.37.11.1331
This study deals with the structural optimization of hybrid vertical-axis wind turbine blades using a response surface method (RSM). The structural analysis results suggest that the stress of hybrid vertical-axis wind turbine blades exceeds the yield strength. Optimization techniques are then applied to structural design to ensure a safe structure. First, the design factors that strongly influence the structural response are identified. The RSM was applied based on the design of experiments. The objective function and constraint terms set the weight and allowable stress, respectively. Furthermore, sensitivity analysis was conducted to indicate the effects of the design factors on the stress and weight. Finally, structural design was performed for the hybrid vertical-axis wind turbine blade.
Spherical Indentation Techniques for Creep Property Evaluation Considering Transient Creep
Lim, Dongkyu ; Lee, Jin Haeng ; Kim, Minsoo ; Lee, Hyungyil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1339~1347
DOI : 10.3795/KSME-A.2013.37.11.1339
Creep through nanoindentations has attracted increasing research attention in recent years. Many studies related to indentation creep tests, however, have simply focused on the characteristics of steady-state creep, and there exist wide discrepancies between the uniaxial test and the indentation test. In this study, we performed a computational simulation of spherical indentations, and we proposed a method for evaluating the creep properties considering transient creep. We investigated the material behavior with variation of creep properties and expressed it using regression equations for normalized variables. We finally developed a program to evaluate the creep properties considering transient creep. By using the proposed method, we successfully obtained creep exponents with an average error less than 1.1 and creep coefficients with an average error less than 2.3 from the load-depth curve.
Sliding Wear Properties of Graphite as Sealing Materials for Cut off Hot Gas
Kim, YeonWook ; Kim, JaeHoon ; Yang, HoYeong ; Park, SungHan ; Lee, HwanKyu ; Kim, BumKeun ; Lee, SeungBum ; Kwak, JaeSu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1349~1354
DOI : 10.3795/KSME-A.2013.37.11.1349
Sealing structure to prevent flowing hot gas into the driving device, located between the driving shaft and the liner of On-Off valve for controlling the hot gas flow path was studied. Wear occurs due to the constant movement of the driving shaft controlled by actuator on graphite as the sealing material. In this paper, the dynamic wear behavior in high temperature of graphite(HK-6) to be used as sealing material was evaluated. Reciprocating wear test was carried out for the graphite(HK-6) to the relative motion between shaft materials(W-25Re). The results of friction coefficient and specific wear rate according to contact load, sliding speed at room temperature and
considering the actual operating environment were evaluated. Through the SEM analysis of the worn surface, third body as lubricant films were observed and lubricant effect of third body was considered.
Effect of Temperature and Thickness on Fracture Toughness of Solid Propellant
Seo, Bo Hwi ; Kim, Jae Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1355~1360
DOI : 10.3795/KSME-A.2013.37.11.1355
A cracked solid propellant would have failure or fracture of rocket because of excessive combustion according to increase of burning area, therefore it is important to evaluate the fracture toughness of solid propellant. A procedure is used to investigate the material under a range of test temperatures between -60 and
, three kind of specimen thickness, 4, 12.5 and 24.5 mm to determine the effect of two parameters on the fracture toughness. A center cracked tension (CCT) specimen is used in these tests, which were conducted using INSTRON 5567 testing machine and environmental chamber to evaluate the fracture toughness. The experimental results show that the fracture toughness tends to decreases with an increase in the temperature, and the effect of thickness indicates that the fracture toughness is highest at 12.5 mm under various temperatures except
. It is found that the fracture toughness of solid propellant is changed due to glass transition behavior around
Design Sensitivity Estimation of Injector Nozzle Hole Considering Cavitation
Yeom, Jeong Kuk ; Ha, Hyeong Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1361~1369
DOI : 10.3795/KSME-A.2013.37.11.1361
This study performs a computational fluid dynamics (CFD) analysis of the inner flow of a multihole injector nozzle by using ANSYS CFX 13.0. Based on the obtained results, a design of experiment (DOE) was performed and applied to investigate the effects of injector nozzle design parameters on cavitation. To analyze the design sensitivity and signal-to-noise ratio (S/N ratio), the hole diameter, hole length, hole angle, and K-factor of the nozzle hole were selected as design parameters, and the effect of these parameters was investigated at 16 experimental points. Consequently, it was found that the effect of the K-factor on the cavitation and inner flow of the injector nozzle is the greatest. Thus, the selection of a suitable K-factor is important in nozzle design considering cavitation flow.
Calculation of Critical Speed of Railway Vehicle by Multibody Dynamics Analysis
Kang, Juseok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1371~1377
DOI : 10.3795/KSME-A.2013.37.11.1371
In this analysis, a method is presented to calculate the critical speed of a railway vehicle by using a multibody dynamic model. The contact conditions and contact forces between the wheel and the rail are formularized for the wheelset model. This is combined with the bogie model to obtain a multibody dynamic model of a railway vehicle with constraint conditions. First-order linear dynamic equations with independent coordinates are derived from the constraint equations and dynamic equations of railway vehicles using the QR decomposition method. Critical speeds are calculated for the wheelset and bogie dynamic models through an eigenvalue analysis. The influences of the design parameters on the critical speed are presented.
Mismatch Limit Load Analyses for V-groove Welded Pipe with Through-wall Circumferential Defect in Centre of Weld
Kim, Sang-Hyun ; Han, Jae-Jun ; Chung, Jin-Taek ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1379~1386
DOI : 10.3795/KSME-A.2013.37.11.1379
The present work reports the mismatch limit loads for a V-groove welded pipe for a circumferential crack using finite element (FE) analyses. To integrate the effect of groove angles on mismatch limit loads, one geometry-related slenderness parameter was modified by relevant geometric parameters including the groove angle, crack depth, and root opening based on plastic deformation patterns in the theory of plasticity. Circumferential through-wall cracks are located at the centre of the weldments with two different groove angles (
). With regard to the loading conditions, axial (longitudinal) tension and bending are applied for all cases. For the parent and weld metal, elastic-perfectly plastic materials are considered to simulate and analyze under- and over-matching conditions in plasticity. The overall results from the proposed solutions are found to be similar to the FE results.
Dynamic Analysis of Railway Vehicle with Wheel Unbalance
Lee, Seung Il ; Choi, Yeon-Sun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1387~1395
DOI : 10.3795/KSME-A.2013.37.11.1387
When the center of mass of a railway wheel is not aligned with the geometrical center of the wheel axis, wheel unbalance occurs. If a railway vehicle runs without removing the wheel unbalance, vibrations will be produced. This will also cause wear and damage of the axle bearing. In this study, dynamic analysis of a railway vehicle with wheel unbalance was conducted to examine the reduction in critical speed and the resonance of the car-body and the effect on the magnitude of wheel unbalance was examined. In addition, the calculation of the car-body vibration owing to static and dynamic unbalance in the railway wheel shows that two-plane balancing is necessary.
Optimum Design Based on Sequential Design of Experiments and Artificial Neural Network for Enhancing Occupant Head Protection in B-Pillar Trim
Lee, Jung Hwan ; Suh, Myung Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1397~1405
DOI : 10.3795/KSME-A.2013.37.11.1397
The optimal rib pattern design of B-pillar trim considering occupant head protection can be determined by two methods. One is the conventional approximate optimization method that uses the statistical design of experiments (DOE) and response surface method (RSM). Generally, approximated optimum results are obtained through the iterative process by trial-and-error. The quality of results strongly depends on the factors and levels assigned by a designer. The other is a methodology derived from previous work by the authors, called the sequential design of experiments (SDOE), to reduce the trial-and-error procedure and to find an appropriate condition for using artificial neural network (ANN) systematically. An appropriate condition is determined from the iterative process based on the analysis of means. With this new technique and ANN, it is possible to find an optimum design accurately and efficiently.
Study on Accelerated Life Testing of Swing Reduction Gear Box for Hybrid Excavator
Park, Jong Won ; Choi, Byung Oh ; Kim, Kyeong Keun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1407~1413
DOI : 10.3795/KSME-A.2013.37.11.1407
The swing motion drive unit of a hybrid excavator is composed of an electrical motor instead of a hydraulic motor that is used in hydraulic excavators. The method to assess and guarantee the reliability of a hybrid excavator should consider combining the mechanical and the electrical failure mode effects. In particular, the swing reduction gear set of a hybrid excavator is operated under severe outdoor conditions; therefore, an accelerated life test, which is based on field operating condition, should be conducted for the newly developed reduction gear set. In this study, various qualitative methods for reliability engineering, such as FMMA, FMECA, FTA, and QFD, were used to develop the accelerated life test method for the swing drive reduction gear set for the hybrid excavator.
Evaluation of Buckling in Prestressed Composite Truss Girder using ADINA Structure Analysis
Kim, Eui Soo ; Kim, Jong Hyuk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1415~1421
DOI : 10.3795/KSME-A.2013.37.11.1415
Recently, to resolve problems regarding legal liability for accidents and disasters, various simulation techniques such as F.E.M. and F.V.M. have been used in the field of forensic engineering. In this study, we performed mechanical structure analysis using ADINA to investigate the cause of bridge collapse accidents. Such accidents occurred owing to modified and missing processes in comparison with the original design while filling with concrete. Modified and missing processes cause buckling of the upper plate and twisting of the main girder. Through this study, we determine the exact cause of bridge collapse by comparing the evaluation of the structure stability of the original design with the evaluation of the structure stability of the modified and missing process using ADINA structure analysis. Hence, this result indicates that buckling prediction through FEA is the most effective method.
Development of Heat Dissipation Measuring System for 1.2-kW BLDC Motor
Lee, Injun ; Ye, Jungwoo ; Lee, Daehun ; Hwang, Pyung ; Shim, Jaesool ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1423~1428
DOI : 10.3795/KSME-A.2013.37.11.1423
In this study, a heat dissipation measurement system is developed to analyze a 1.2-kW BLDC motor. It is important to check the temperature of the motor because an increase in temperature causes problems in the motor insulations, which in turn influences the motor life. A generator for a vehicle is installed to set up a load. We changed the load from 165 to 495 W. While the rpm varies from 2000 to 4000 under various load conditions, the changes in temperature were measured for the operating period by using a thermocouple. The results of experiments conducted under natural convection conditions suggest that the temperature was not stationary with the rpm, load, and coil of the motor and it kept increasing over
. However, under forced convection conditions, the temperature stationarily reached
after 4000 s. The difference between the maximum and the minimum temperatures was
with an increase in the rpm and load. The orders of high temperature were as follows: motor coil (Ch#1), side of motor surface (Ch#5), inside of motor cap (Ch#2), upper side of motor surface (Ch#4), and inner wall of the motor (Ch#3).
Design of Rollover Prevention Controller Using Game-Theoretic Approach
Yim, Seongjin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1429~1436
DOI : 10.3795/KSME-A.2013.37.11.1429
This study presents an approach for designing a vehicle rollover prevention controller using differential game theory and multi-level programming. The rollover prevention problem can be modeled as a non-cooperative zero-sum two-player differential game. A controller as an equilibrium solution of the differential game guarantees the worst-case performance against every possible steering input. To obtain an equilibrium solution to the differential game with a small amount of computational effort, a multi-level programming approach with a relaxation procedure is used. To cope with the loss of maneuverability caused by the active suspension, an electronic stability program (ESP) is adopted. Through simulations, the proposed method is shown to be effective in obtaining an equilibrium solution of the differential game.
Running Safety Analysis of Railway Vehicle Depending on Railway Inclination Change Under Actual Track Conditions
Kim, Moon Ki ; Eom, Beom Gyu ; Lee, Hi Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 11, 2013, Pages 1437~1443
DOI : 10.3795/KSME-A.2013.37.11.1437
Railways are currently subject to the enforcement of speed limits for each curve as prescribed by the Railway Operating Rules in Korea. However, research is required to determine the maximum speed of trains passing through each curve that allows them to run without the risk of derailment in relation to the speed enhancement of existing railway tracks. In addition, factors affecting the running safety of railway vehicles can be classified into those in terms of vehicle aspects and those in terms of track aspects. This study sought to analyze the running safety of railway vehicles according to changes in the inclination of the rail from among the factors affecting the enhancement of safety against derailment. To increase the speed of trains passing through curves that have high derailment risk, this study also analyzed the running safety of railway vehicles according to the inclination of the rail and changes in running speed while a vehicle passes through each curve section in both the up and the down train line sections between Namsunghyun and Chungdo, which represent the actual conditions of railway tracks.