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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 38, Issue 12 - Dec 2014
Volume 38, Issue 11 - Nov 2014
Volume 38, Issue 10 - Oct 2014
Volume 38, Issue 9 - Sep 2014
Volume 38, Issue 8 - Aug 2014
Volume 38, Issue 7 - Jul 2014
Volume 38, Issue 6 - Jun 2014
Volume 38, Issue 5 - May 2014
Volume 38, Issue 4 - Apr 2014
Volume 38, Issue 3 - Mar 2014
Volume 38, Issue 2 - Feb 2014
Volume 38, Issue 1 - Jan 2014
Selecting the target year
Development of Multi-Body Dynamics Simulator for Bio-Mimetic Motion in Lizard Robot Design
Park, Yong-Ik ; Seo, Bong Cheol ; Kim, Sung-Soo ; Shin, Hocheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 585~592
DOI : 10.3795/KSME-A.2014.38.6.585
In this study, a multibody simulator was developed to analyze the bio-mimetic motion of a lizard robot design. A RecurDyn multibody dynamics model of a lizard was created using a micro-computerized tomography scan and motion capture data. The bio-mimetic motion simulator consisted of a trajectory generator, an inverse kinematics module, and an inverse dynamics module, which were used for various walking motion analyses of the developed lizard model. The trajectory generation module produces spinal movements and gait trajectories based on the lizard's speed. Using the joint angle history from an inverse kinematic analysis, an inverse dynamic analysis can be carried out, and the required joint torques can be obtained for the lizard robot design. In order to investigate the effectiveness of the developed simulator, the required joint torques of the model were calculated using the simulator.
Torque Assist Strategy for Hybrid Agricultural Tractor with Consideration of Field Operations
Choi, Sangchun ; Song, Bongsob ; Kim, Yongjoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 593~600
DOI : 10.3795/KSME-A.2014.38.6.593
This paper proposes a torque assist strategy for operating a hybrid agricultural tractor in the field. In general, different field operations such as baling and rotary tillage require different patterns and amounts of torque. Thus, a large agricultural tractor is used to improve the farming efficiency. Therefore, this research has the goal of developing a hybrid tractor that uses a small electric motor to provide additional torque for specific field operations. To achieve this objective, a rule-based torque assist strategy is proposed and validated for a simulation model in the Autonomie framework, which is a commercial simulation tool. Finally, the work efficiencies and fuel consumptions of a conventional tractor and the hybrid tractor with the proposed torque assist strategy are compared using simulations.
Study on Analysis Method for Fire Safety Test of Hydrant Reducing Valve for Offshore Plant
Jeong, Yun Sang ; Kang, Jung Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 601~608
DOI : 10.3795/KSME-A.2014.38.6.601
An offshore plant is vulnerable to fire because of the isolated environment. In particular, the damage to an offshore plant is increased when a hydrant reducing valve, which is a main piece of equipment in an offshore plant, is damaged in a fire. In this study, we conducted a fire safety test for a hydrant reducing valve and proved the validity of our analysis by comparing the results of the test and analysis. Therefore, we here suggest an analysis method for a fire safety test. FSI(fluid structure interaction) was considered in the fire safety test. The reliability of the analysis method was verified by comparing the temperature distributions of the test and analysis. In addition, we verified the problems that were caused in the fire safety test by conducting a structure analysis. At a result, the main problem was found to be deformation of the valve seat.
Aerodynamic Characteristics of Several Airfoils for Design of Passive Pitch Control Module of 10 kW Class
Kang, Sang Kyun ; Lee, Ji Hyun ; Lee, Jang-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 609~617
DOI : 10.3795/KSME-A.2014.38.6.609
Even though the variable pitch control of a wind turbine blade is known as an effective component for power control over the rated wind speed, it has limited applicability to small wind turbines because of its relatively high cost on the price of small wind turbine. Instead, stall control is generally applied in the blade design without any additional cost. However, stall delay can frequently be caused by high turbulence around the turbine blade, and it can produce control failures through excessive rotational speed and overpowering the electrical generator. Therefore, a passive pitch control module should be considered, where the pitch moves with the aerodynamic forces of the blade and returns by the elastic restoring force. In this study, a method to calculate the pitch moment, torque, and thrust based on the lift and drag of the rotating blade wing was demonstrated, and several effective wing shapes were reviewed based on these forces. Their characteristics will be estimated with variable wind speed and be utilized as basic data for the design of the passive pitch control module.
Preliminary Study on Structural Optimization with Control Variables Using Equivalent Static Loads for Spring-damper Control Systems
Yoo, Nam-Sun ; Jung, Ui-Jin ; Park, Gyung-Jin ; Kim, Tai-Kyung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 619~627
DOI : 10.3795/KSME-A.2014.38.6.619
An optimization method is proposed for the simultaneous design of structural and control systems using the equivalent static loads. In the past researches, the control parameters of such feedback gains are obtained to improve some performance in the steady-state. However, the actuators which have position and velocity feedback gains should be designed to exhibit a good performance in the time domain. In other words, the system analysis should be conducted for the transient-state in dynamic manner. In this research, a new equivalent static loads method is presented to treat the control variables as the design variables. The equivalent static loads (ESLs) set is defined as a static load set which generates the same displacement field as that from dynamic loads at a certain time. The calculated sets of ESLs are applied as multiple loading conditions in the optimization process. Several examples are solved to validate the proposed method.
Analysis and Mechanical Behavior of Coating Layer in Metallic Glass Matrix Composite
Jang, Beom Taek ; Yi, Seong Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 629~636
DOI : 10.3795/KSME-A.2014.38.6.629
For surface modification, bulk metallic glass coatings were fabricated using metallic glass powder and a mixture of a self-fluxing alloy or/and hard metal alloys with a heat-resisting property using a high velocity oxy-fuel coating thermal spraying process. Microstructural analyses and mechanical tests were carried out using X-ray diffraction, a scanning electron microscope, an atomic force microscope, a three-dimensional optical profiler, and nanoindenation. As a result, the monolithic metallic glass coating was found to consist of solid particle and lamellae regions that included many pores. Second phase-reinforced composite coatings with a self-fluxing alloy or/and hard metal alloy additives were employed with in-situ
precipitate or/and ex-situ WC particles in an amorphous matrix. The mechanical behaviors of the solid particles and lamella regions showed large hardness and elastic modulus differences. The mechanical properties of the particle regions in the metallic glass composite coatings were superior to those of the lamellae regions in the monolithic metallic glass coatings, but indicated similar trends in matrix region of all the coating layers.
Effects of Repair Weld of Reactor Pressure Vessel Upper Head Control Rod Drive Mechanism Penetration Nozzle on J-Groove Weldment Using Finite Element Analysis
Kim, Ju Hee ; Yoo, Sam Hyeon ; Kim, Yun Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 637~647
DOI : 10.3795/KSME-A.2014.38.6.637
In pressurized water reactors, the upper head of the reactor pressure vessel (RPV) contains numerous control rod drive mechanism (CRDM) nozzles. These nozzles are fabricated by welding after being inserted into the RPV head with a room temperature shrink fit. The tensile residual stresses caused by this welding are a major factor in primary water stress corrosion cracking (PWSCC). Over the last 15 years, the incidences of cracking in alloy 600 CRDM nozzles have increased significantly. These cracks are caused by PWSCC and have been shown to be driven by the welding residual stresses and operational stresses in the weld region. Various measures are being sought to overcome these problems. The defects resulting from the welding process are often the cause of PWSCC acceleration. Therefore, any weld defects found in the RPV manufacturing process are immediately repaired by repair welding. Detailed finite-element simulations for the Korea Nuclear Reactor Pressure Vessel were conducted in order to predict the magnitudes of the repair weld residual stresses in the tube materials.
Reliability-Based Design Optimization Considering Variable Uncertainty
Lim, Woochul ; Jang, Junyong ; Kim, Jungho ; Na, Jongho ; Lee, Changkun ; Kim, Yongsuk ; Lee, Tae Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 649~653
DOI : 10.3795/KSME-A.2014.38.6.649
Although many reliability analysis and reliability-based design optimization (RBDO) methods have been developed to estimate system reliability, many studies assume the uncertainty of the design variable to be constant. In practice, because uncertainty varies with the design variable's value, this assumption results in inaccurate conclusions about the reliability of the optimum design. Therefore, uncertainty should be considered variable in RBDO. In this paper, we propose an RBDO method considering variable uncertainty. Variable uncertainty can modify uncertainty for each design point, resulting in accurate reliability estimation. Finally, a notable optimum design is obtained using the proposed method with variable uncertainty. A mathematical example and an engine cradle design are illustrated to verify the proposed method.
Evaluation of Tensile Properties of Alloy 690TT Steam Generator Tube at Room Temperature and 343℃
Eom, Ki Hyeon ; Kim, Jin Weon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 655~662
DOI : 10.3795/KSME-A.2014.38.6.655
This study conducted tensile tests on an Alloy 690TT tube at room temperature (RT) and at
using tube- and ring-type specimens to investigate the stress-strain behavior and tensile properties of a steam generator (SG) tube in the axial and circumferential directions at RT and at the design temperature of a nuclear power plant (NPP). The results of the axial tensile test showed that yield point phenomena appeared at both RT and
, and serrated flow in the stress-strain curve appeared at
. Yield and tensile strengths for both directions were clearly lower at
compared to RT; however, the elongations were approximately the same at both test temperatures. Regardless of the test temperature, the strengths in the circumferential direction were lower by approximately 5~10 % than those in the axial direction. In addition, the test data revealed that the reduction in the yield and tensile strengths of the Alloy 690TT SG tube with the test temperature was more significant than that estimated by the temperature correction factor of ASME Sec.II.
Simulation and Design of High-Speed Hydraulic Velocity Generator in Shock Test Machine
Kim, Tae Hyeong ; Shul, Chang Won ; Kim, Yoon Jae ; Yang, Myung Seog ; Lee, Gyu Sub ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 663~668
DOI : 10.3795/KSME-A.2014.38.6.663
Mechanical and electrical devices in various forms are used in many different fields. These can be exposed to external environmental factors such as shock. Therefore, a shock test machine is commonly used to test these devices and evaluate their shock resistance. In this test, the break-down or permanent deformation and malfunction of inner parts due to a high stress or acceleration can be evaluated. As part of a shock test machine, a velocity generator is needed to create shocks between objects. In this study, a hydraulic velocity generator was conceptually designed and an AMESim model was developed to simulate the velocity under different conditions. Simulation results using this model were compared with the test results from a reduced-size velocity generator, and we designed a velocity generator that fits the target payload and velocity using the simulation results.
Probabilistic Estimation of Thermal Fatigue Performance of Three-Way Catalyst Substrate
Cho, Seok-Swoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 669~676
DOI : 10.3795/KSME-A.2014.38.6.669
A three-way catalyst substrate for domestic passenger car satisfies the design criteria for exhaust gas exchange and pressure drop but does not have satisfactory thermal fatigue performance. Prefracture faults in this three-way catalyst substrate has often been discovered in vehicle repair or vehicle inspection facilities. This paper presents a thermal fatigue performance estimation method for a three-way catalyst substrate using a probabilistic strength reduction factor model. This method is superior to the thermal fatigue performance estimation method for a three-way catalyst substrate that uses a deterministic strength model.
Design Analysis of Current Density in Lithium Secondary Battery Using Data Mining Techniques
Jeong, Dong Ho ; Lee, Jongsoo ; Choi, Ha-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 677~682
DOI : 10.3795/KSME-A.2014.38.6.677
In the present study, a decision tree and artificial neural network were used to determine critical design parameters for lithium ion batteries and compare their performances. First, a design method that used a decision tree-artificial neural network model was used to determine the major design factors among early pole plate design factors that showed nonlinearity. Then, the artificial neural network was used to implement a weighted value analysis of the importance of the design factors and their effect on the current density. The second method involved the use of an artificial neural network model to construct artificial networks without separate determinations of the major early design factors to analyze the connections and weighted values related to the current density.
Factor Effects of Low-Frequency Instability of Brake System Using Complex Eigenvalue Analysis
Lee, Ik Hwan ; Jeong, Wontae ; Park, Kyung Hwan ; Lee, Jongsoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 683~689
DOI : 10.3795/KSME-A.2014.38.6.683
The present study conducted a parameter effect analysis of low-frequency squeal noise using a numerical simulation. The finite element program ABAQUS was used to calculate the dynamic instability based on a complex eigenvalue analysis. A total of five parameters, including the chassis, wear, piston, material property, and contact condition, were selected to identify the factor effects on a low-frequency squeal noise between 2.5 and 3.1 kHz. The present study found the dominant level of each factor through an analysis of the means in the context of the experiment design.
Manufacturing Process and Basic Property Tests of Composite Helicopter Rotor Hub System
Kee, Youngjung ; Kim, Taejoo ; Yun, Chulyong ; Kim, Doegkwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 6, 2014, Pages 691~698
DOI : 10.3795/KSME-A.2014.38.6.691
This paper describes the manufacturing processes for a flexbeam and torque tube made of composite materials, along with the procedures for testing their basic properties. A flexbeam and torque tube can be considered to be key structural components of a bearingless rotor hub system. A hinge offset effect can be realized by a large elastic deformation and twist of the flexbeam, and the blade pitch control forces are transferred by the rotation of the torque tube. The basic property tests included bending and twist tests to determine the flap stiffness, lag stiffness, and torsion stiffness of the flexbeam, torque tube, and blade, and these tests were performed prior to starting the whirl tower test. In addition, the estimated results were compared with experimental data, and the calculations were found to be a good match for the analysis results and had a similar tendency. Through these results, we could confirm that a flexbeam and torque tube made of composite materials satisfied the structural stiffness requirements.