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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 39, Issue 12 - Dec 2015
Volume 39, Issue 11 - Nov 2015
Volume 39, Issue 10 - Oct 2015
Volume 39, Issue 9 - Sep 2015
Volume 39, Issue 8 - Aug 2015
Volume 39, Issue 7 - Jul 2015
Volume 39, Issue 6 - Jun 2015
Volume 39, Issue 5 - May 2015
Volume 39, Issue 4 - Apr 2015
Volume 39, Issue 3 - Mar 2015
Volume 39, Issue 2 - Feb 2015
Volume 39, Issue 1 - Jan 2015
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Three-Dimensional Shape Estimation of Beam Structure Using Fiber Bragg Grating Sensors
Lee, Jin-Hyuk ; Kim, Heon-Young ; Kim, Dae-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 241~247
DOI : 10.3795/KSME-A.2015.39.3.241
Deflection and deformation occur easily in structures with long length, such as bridges and pipelines. Shape monitoring is required for ensuring their structural health. A fiber Bragg grating (FBG) sensor can be used for monitoring a large-scale structure because of its advantage of multiplexing. In this study, FBG sensors were used for monitoring a composite beam structure, and its strains were measured at multiple points. Thereafter, a shape estimation technique based on the strains was studied. Particularly, a three-dimensional shape estimation technique was proposed for accurate structural health monitoring. A simple experiment was conducted to verify the performance of the shape estimation technique. The result revealed that the estimated shape of the composite beam structure was in agreement with the actual shape obtained after the deformation of the specimen. Additionally, the deflection at a specific point was verified by comparing the estimated and actual deformations measured using a micrometer.
Simulation of Asymmetric Fuel Thermal Behavior Using 3D Gap Conductance Model
Kang, Chang Hak ; Lee, Sung Uk ; Yang, Dong Yol ; Kim, Hyo Chan ; Yang, Yong Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 249~257
DOI : 10.3795/KSME-A.2015.39.3.249
A fuel assembly consists of fuel rods composed of pellets (UO2) and a cladding tube (Zircaloy). The role of the fuel rods in the reactor is to generate heat by nuclear fission, as well as to retain fission products during operation. A simulation method using a computer program was used to evaluate the safety of the nuclear fuel rods. This computer program has been called the fuel performance code. In the analysis of a light water reactor fuel rod, the gap conductance, which depended on the distance between the pellets and cladding tube, mainly influenced the thermomechanical behavior of the fuel rod. In this work, a 3D gap element was proposed to simulate the thermo-mechanical behavior of the nuclear fuel rod, considering the gap conductance. To implement the proposed 3D gap element, a 3D thermo-mechanical module was also developed using FORTRAN90. The asymmetric characteristics of the nuclear fuel rod, such as the MPS (missing pellet surface) and eccentricity, were simulated to evaluate the proposed 3D gap element.
Preliminary Study on Optimization of the Tube Hydroforming Process Using the Equivalent Static Loads
Jang, Hwan-Hak ; Park, Gyung-Jin ; Kim, Tai-Kyung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 259~268
DOI : 10.3795/KSME-A.2015.39.3.259
An optimization method for the tube hydroforming process is developed using the equivalent static loads method for non linear static response structural optimization (ESLSO). The aims of the tube hydroforming optimization are to determine the axial forces (axial feedings) and the internal pressures, and to obtain the desired shape without failures after hydroforming analysis. Therefore, the magnitude of the forces should be design variables in the optimization process. Also, some tube hydroforming optimization needs to consider the result of the thickness in nonlinear dynamic analysis as responses. However, the external forces are considered as constants and the thickness is not a response in the linear response optimization process of the original ESLSO. Thus, a new ESLSO process is proposed to overcome the difficulties and some examples are solved to validate the proposed method.
Investigation on Effect of Distance Between Two Collinear Circumferential Surface Cracks on Primary Water Stress Corrosion Crack Growth in Alloy 600TT Steam Generator Tubes
Heo, Eun-Ju ; Kim, Jong-Sung ; Jeon, Jun-Young ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 269~273
DOI : 10.3795/KSME-A.2015.39.3.269
The study investigated the effect of the distance between two collinear circumferential surface cracks on the primary stress corrosion crack (PWSCC) growth in alloy 600TT steam generator tubes using a finite element damage analysis based on the PWSCC initiation model and macroscopic phenomenological damage mechanics approach. The damage analysis method was verified by comparing the results to the previous study results. The verified method was applied to collinear circumferential surface PWSCCs. As a result, it was found that the collinear cracks showed earlier coalescence and penetration times than the a single crack, and the times increased with the distance. In addition, it is expected that penetration may occur before coalescence of two cracks if they are more than a specific distance apart.
Lumped Track Modeling for Estimating Traction Force of Vecna BEAR Type Robot
Kim, Tae Yun ; Jung, Samuel ; Yoo, Wan Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 275~282
DOI : 10.3795/KSME-A.2015.39.3.275
Recently, Vecna BEAR type robot to save injured individuals from inaccessible areas has been developed to minimize the loss of life. Because this robot is driven on rough terrain, there is a risk of rollover and vibration, which could impact the injured. In order to guarantee its stability, an algorithm is required that can estimate the speed limits for various environments in real time. Therefore, a dynamic model for real-time analysis is needed for this algorithm. Because the tracks used as the driving component of Vecna BEAR type robot consist of many parts, it is impossible to analyze the multibody tracks in real time. Thus, a lumped track model that satisfies the requirements of a short computation time and adequate accuracy is required. This study performed lumped track modeling, and the traction force was verified using RecurDyn, which is a dynamic commercial program.
Lightweight Design of Brake Bracket for Composite Bogie Using Topology Optimization
Lee, Woo Geun ; Kim, Jung Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 283~289
DOI : 10.3795/KSME-A.2015.39.3.283
In this study, the lightweight design of a brake bracket for a composite bogie was studied by considering two brake bracket models with thicknesses of 12t and 9t, respectively. For achieving this goal, finite element analysis and topology optimization were conducted. Firstly, the largest cross-sectional areas of the vertical and horizontal plates of the brake bracket were selected as the design variables. As the constraint, the Z-axis displacement of the brake bracket was increased by 2.5 units from the initial displacement value. The minimum volume fraction of the design regions was chosen as the objective function. The full model comprised a composite bogie frame and brackets attached together. However, to reduce the analysis time, 1D beam elements were used instead of the composite bogie frame by ensuring its equivalence with the full model. The result revealed that the weights of the 12t and 9t models of the brake bracket were reduced to 60 kg and 31 kg, respectively.
Design Verification System Framework of Pressure Vessels Using Korea Industrial Standards
Lee, Jaechul ; Kim, Ikjune ; Lim, Chae Ho ; Hwang, Jinsang ; Mun, Duhwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 291~301
DOI : 10.3795/KSME-A.2015.39.3.291
Product regulations specify requirements or constraints for products that manufacturers must comply with across the entire product lifecycle, from design and manufacture, through operation and maintenance, to recycling and disposal. This paper suggests a system framework and its essential components for the verification of a pressure vessel design using the industrial standards of Korea. The authors also present methods to generate design template data from legacy design systems and to construct a regulation knowledge base. The proposed framework is demonstrated through experiments involving pressure vessel design verification using a prototype system.
Investigation of Vehicle Dynamic Behavior of Composite Bogie Under Different Rubber Bushing Stiffness Values
Kim, Il Kyeom ; Kim, Jung Seok ; Lee, Woo Geun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 303~309
DOI : 10.3795/KSME-A.2015.39.3.303
In this study, a vehicle dynamic analysis and roller rig test were performed to evaluate the applicability of a suspensionless composite bogie to railway vehicles. A vehicle dynamic analysis was carried out under different rubber bushing stiffness values. The stiffness of the rubber bushing that plays a role in guiding wheel sets was varied in the range of 10-100 MN/m, in 10-MN/m steps. Based on the results, the composite bogie with a rubber bushing stiffness of more than 40 MN/m satisfied the design requirements. In addition, a rubber bushing with a stiffness of 81 MN/m was fabricated, and a roller rig test was performed. Based on the test results, the vehicle equipped with the composite bogie had a critical speed of 363 km/h, which agreed with the simulation result within an error of 10%.
Optimization of the Television Packing System Using Equivalent Static Loads
Lee, Youngmyung ; Jung, Ui-Jin ; Park, Gyung-Jin ; Han, In-Sik ; Kim, Tai-Kyung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 311~318
DOI : 10.3795/KSME-A.2015.39.3.311
A nonlinear dynamic response structural optimization process is proposed for the television (TV) packing system that protects the damage from a drop situation using the equivalent static loads (ESLs). Topology optimization using ESLs is carried out for conceptual design, and shape optimization using stress ESLs for a virtual model is performed for detailed design. Stress ESLs are static loads that generate the same displacement as well as the stress fields of linear static analysis as those of nonlinear dynamic analysis. Thus, the response of nonlinear dynamic analysis can be utilized as a constraint in the linear static structural optimization. An actual example is solved to validate the process. The drop test of a television packaging system is analyzed by LS-DYNA, and NASTRAN is used for optimization.
Study on Fatigue Characteristics of High-Strength Steel Welds
Chang, Hong Suk ; Yoo, Seung Won ; Park, Jong Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 319~325
DOI : 10.3795/KSME-A.2015.39.3.319
High-strength steel has replaced mild steel as the material of choice for truck decks or frames, owing to the growing demand for lightweight vehicles. Although studies on the weld fatigue characteristics of mild steel are available, studies on high-strength steels have been seldom conducted. In this study, firstly, we surveyed a chosen number of approaches and selected the Radaj method, which uses the notch factor approach, as the one suitable for evaluating the fatigue life of commercial vehicles. Secondly, we obtained the S-N curves of HARDOX and ATOS60 steel welds, and the F-N curves of the T-weld and overlapped-weld structures. Thirdly, we acquired a general S-N curve of welded structures made of high-strength steel from the F-N curve, using the notch factor approach. Fourthly, we extracted the weld fatigue characteristics of high-strength steel and incorporated the results in the database of a commercial fatigue program. Finally, we compared the results of the fatigue test and the CAE prediction of the example case, which demonstrated sufficiently good agreement.
Independent Cooling Controller for Temperature Control of High Strength and Atmosphere Corrosion Resisting Steel in Hot Strip Mills
Park, Cheol Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 327~335
DOI : 10.3795/KSME-A.2015.39.3.327
In this paper, we propose an independent cooling control (ICC) scheme for high strength and atmosphere corrosion resisting steel to obtain the desired temperature and properties along the longitudinal direction of the steel in the run-out table (ROT) process. A temperature model of the independent process is developed to divide the ROT into front and back sections. The control concept uses field data, problem analysis, and a time-temperature transformation diagram. The effectiveness of the proposed control is verified using simulation results under a temperature disturbance by the transformation in the middle of the ROT. The results of a hot strip mill field test show that the temperature control performance is significantly improved by the proposed control scheme.
Automatic Generation of CAM Model for Machining Holes for Jet Engine Compressor Case Based on Feature Recognition
Kim, Byung Chul ; Song, Ilhwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 337~345
DOI : 10.3795/KSME-A.2015.39.3.337
High machining technology is needed for manufacturing jet engines for use in aircrafts. To reduce errors in the jet engine machining process, the machining companies of aircraft engines have introduced the CAM (computer-aided manufacturing) technology. However, to create a CAM model, the operator must manually conduct machining operations based on a CAD (computer-aided design) model, which can take several days or weeks. To solve this problem, this study proposes a method for automatically generating a CAM model for machining holes in the parts, using a CAD model. In this method, the features of the hole are recognized from the CAD model and translated into machining operations to be used with the CATIA program. Additionally, a prototype system was implemented and the proposed method was experimentally verified.
Model-Based Detection of Pipe Leakage at Joints
Kim, Taejin ; Youn, Byeng D. ; Woo, Sihyeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 3, 2015, Pages 347~352
DOI : 10.3795/KSME-A.2015.39.3.347
Time domain reflectometry (TDR) is widely used for wire failure detection. It transmits a pulse that is reflected at the boundaries of different characteristic impedances. By analyzing the reflected signal, TDR makes it possible to locate the failure. In this study, TDR was used to detect the water leakage at a pipe joint. A wire attached to the pipe surface was soaked by water when a leak occurred, which affected the characteristic impedance of the wet part, resulting in a change in the reflected signal. To infer the leakage from the TDR signal, we first developed a finite difference time domain-based forward model that provided the output of the TDR signal given the configuration of the transmission line. Then, by solving the inverse problem, the locations of the leaks were found.