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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
Selecting the target year
Evaluation of Limit Loads for Circumferentially Cracked Pipes Under Combined Loadings
Ryu, Ho-Wan ; Han, Jae-Jun ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 453~460
DOI : 10.3795/KSME-A.2015.39.5.453
Since the Fukushima nuclear accident, several researchers are extensively studying the effect of torsion on the piping systems In nuclear power plants. Piping installations in power plants with a circumferential crack can be operated under combined loading conditions such as bending and torsion. ASME Code provides flaw evaluations for fully plastic fractures using limit load criteria for the structural integrity of the cracked pipes. According to the recent version of Code, combined loadings are provided only for the membrane and bending. Even though actual operating conditions have torsion loading, the methodology for evaluating torsion load is not established. This paper provides the results of limit load analyses by using finite element models for circumferentially cracked pipes under pure bending, pure torsion, and combined bending and torsion with tension. Theoretical limit load solutions based on net-section fully plastic criteria are suggested and verified with the results of finite element analyses.
Vibration Analysis of AFM Microcantilevers Using an Equivalent Stiffness Element Model
Han, Dong Hee ; Kim, Il Kwang ; Lee, Soo Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 461~466
DOI : 10.3795/KSME-A.2015.39.5.461
Atomic force microscopy (AFM) is powerful tool for determining properties of samples based on interactions between the sample surface and an approaching probe tip. In this study, we modeled the interactions between the sample and the tip of the AFM microcantilever as a single nonlinear spring with an equivalent stiffness element and simulated the dynamic behaviors of the AFM microcantilevers using the finite element method (FEM) and ANSYS software. With the simulation results, we analyzed the complex dynamic responses of the AFM cantilever using proper orthogonal decomposition (POD). In addition, we compared the simulation and experimental results using the same method. Consequently, we suggest an effective method to express the interaction between the tip and sample, and we confirm that the influence of the higher order model due to the interaction between the tip and sample is increased.
Evaluation of Mechanical Property for Pb-free Solder/Ni Plate Joints with Artificial Aging Time
Park, So Young ; Yang, Sung Mo ; Yu, Hyo Sun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 467~471
DOI : 10.3795/KSME-A.2015.39.5.467
Thus far, solders used in electronics remain lead-based. Pb-free solutions in electronic components and systems are receiving increased attention in the semiconductor and electronics industries. Pb-free materials currently in used are Sn-37Pb, Sn-4Ag and Sn-4Ag-0.5Cu/Ni plate joints. In this study, solder alloys were used at high temperatures for artificial aging processing that was performed at
for 0hr, 100hr, 200hr, 400hr, 600hr and 1000hr. The SP test was conducted at
. As a result, the maximum shear strength of all the specimens decreased with the increase in artificial aging time and temperature of the SP test. In addition, Pb-free solders showed higher total fracture energy compared with Sn-37Pb at high temperatures. The mechanical properties of Sn-4Ag-0.5Cu solder/Ni plate joints remained in excellent conditions in electronic parking systems at high temperatures.
A Study on Mode Confusions in Adaptive Cruise Control Systems
Ahn, Dae Ryong ; Yang, Ji Hyun ; Lee, Sang Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 473~482
DOI : 10.3795/KSME-A.2015.39.5.473
Recent development in science and technology has enabled vehicles to be equipped with advanced autonomous functions. ADAS (Advanced Driver Assistance Systems) are examples of such advanced autonomous systems added. Advanced systems have several operational modes and it has been observed that drivers could be unaware of the mode they are in during vehicle operation, which can be a contributing factor of traffic accidents. In this study, possible mode confusions in a simulated environment when vehicles are equipped with an adaptive cruise control system were investigated. The mental model of the system was designed and verified using the formal analysis method. Then, the user interface was designed on the basis of those of the current cruise control systems. A set of human-in-loop experiments was conducted to observe possible mode confusions and redesign the user interface to reduce them. In conclusion, the clarity and transparency of the user interface was proved to be as important as the correctness and compactness of the mental model when reducing mode confusions.
Real-time Simultaneous Localization and Mapping (SLAM) for Vision-based Autonomous Navigation
Lim, Hyon ; Lim, Jongwoo ; Kim, H. Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 483~489
DOI : 10.3795/KSME-A.2015.39.5.483
In this paper, we propose monocular visual simultaneous localization and mapping (SLAM) in the large-scale environment. The proposed method continuously computes the current 6-DoF camera pose and 3D landmarks position from video input. The proposed method successfully builds consistent maps from challenging outdoor sequences using a monocular camera as the only sensor. By using a binary descriptor and metric-topological mapping, the system demonstrates real-time performance on a large-scale outdoor dataset without utilizing GPUs or reducing input image size. The effectiveness of the proposed method is demonstrated on various challenging video sequences.
Effect of Temperature on Interlaminar Fracture Toughness of Filament-Wound Carbon/Epoxy Composites
Im, JaeMoon ; Shin, KwangBok ; Hwang, Taekyung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 491~497
DOI : 10.3795/KSME-A.2015.39.5.491
This paper reports an experimental study for evaluating the effect of temperature on the mode I, mode II and mixed-mode interlaminar fracture toughness of adhesive joints with a curved cross-section of filament-wound dome-separated composite pressure vessel. Mode I and mixed-mode interlaminar fracture toughness were evaluated using DCB specimens, while mode II interlaminar fracture toughness was determined using ENF specimens.
) winding specimens with the curved cross-section were considered. In-situ temperature environments were simulated with a range of
using an environmental chamber and furnace. Experimental results on the effect of temperature indicate that interlaminar fracture toughness tends to be high at low temperature and is degraded with increase in temperature. For specimen types, it was found that interlaminar fracture toughness of
winding specimens considered as adhesive joints of dome and helical part was higher than other specimens.
On the Energy Conversion Efficiency of Piezoelectric Vibration Energy Harvesting Devices
Kim, Jae Eun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 499~505
DOI : 10.3795/KSME-A.2015.39.5.499
To properly design and assess a piezoelectric vibration energy harvester, it is necessary to consider the application of an efficiency measure of energy conversion. The energy conversion efficiency is defined in this work as the ratio of the electrical output power to the mechanical input power for a piezoelectric vibration energy harvester with an impedance-matched load resistor. While previous research works employed the electrical output power for approximate impedance-matched load resistance, this work derives an efficiency measure considering optimally matched resistance. The modified efficiency measure is validated by comparing it with finite element analysis results for piezoelectric vibration energy harvesters with three different values of the electro-mechanical coupling coefficient. New findings on the characteristics of energy conversion and conversion efficiency are also provided for the two different impedance matching methods.
Design of a Torque Application Device in Test Rig for a Wind Turbine Gearbox
Kim, Jeong-Gil ; Park, Young-Jun ; Lee, Geun-Ho ; Nam, Yong-Yun ; Oh, Joo-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 507~515
DOI : 10.3795/KSME-A.2015.39.5.507
This study was conducted to develop and verify a torque application device for use in a mechanical power-circulation test rig for 5.5 MW wind turbine gearboxes. The design and analysis of the torque application device was conducted. In addition, the torsional stiffness of the test rig was calculated using the rotational angle measurements for each of the components. The calculated stiffness of the test rig was
for a clockwise torque application. The rated torque can be applied when the stiffness of the gearbox is greater than
for a clockwise torque application. Because of the limited rotational angle of the test rig, the potential application of the rated torque is determined according to the torsional stiffness of the test gearbox.
Attitude Control of Quad-rotor by Improving the Reliability of Multi-Sensor System
Yu, Dong Hyeon ; Park, Jong Ho ; Ryu, Ji Hyoung ; Chong, Kil To ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 517~526
DOI : 10.3795/KSME-A.2015.39.5.517
This paper presents the results of study for improving the reliability of quadrotor attitude control by applying a multi-sensor along with a data fusion algorithm. First, a mathematical model of the quadrotor dynamics was developed. Then, using the quadrotor mathematical model, simulations were performed using the improved reliability multi-sensor data as the inputs. From the simulation results, we designed a Gimbal-equipped quadrotor system. With the quadrotor in a hover state, we performed experiments according to the angle change of the user's specifications. We then calculated the attitude control data from the actual experimental data. Furthermore, with additional simulations, we verified the performance of the designed quadrotor attitude control system with multiple sensors.
Optimum Yaw Moment Distribution with ESC and AFS Under Lateral Force Constraint on AFS
Yim, Seongjin ; Lee, Jungjae ; Cho, Sung Ik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 527~534
DOI : 10.3795/KSME-A.2015.39.5.527
This paper presents an integrated chassis control with electronic stability control (ESC) and active front steering (AFS) under lateral force constraint on AFS. The control yaw moment is calculated using a sliding mode control. The tire forces generated by ESC and AFS are determined using weighted pseudo-inverse based control allocation (WPCA) in order to generate the control yaw moment. On a low friction road, AFS is not effective when the lateral tire forces of front wheels are easily saturated. To solve problem, the lateral force of AFS is limited to its maximum and the braking of ESC is applied with WPCA. To evaluate the effectiveness of the proposed method, a simulation was performed on the vehicle simulation package,
. From the simulation, it was verified that the proposed method could enhance the maneuverability and lateral stability if the lateral force of AFS exceeds its maximum.
Approximate Multi-Objective Optimization of A Wall-mounted Monitor Bracket Arm Considering Strength Design Conditions
Doh, Jaehyeok ; Lee, Jongsoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 535~541
DOI : 10.3795/KSME-A.2015.39.5.535
In this study, an approximate multi-objective optimization of a wall-mounted monitor bracket arm was performed. The rotation angle of the bracket arm was determined considering the inplane degree of freedom. We then formulated an optimization problem on maximum stress and deflection. Analyses of mean and design parameters were conducted for sensitivity regarding performance with orthogonal array and response surface method (RSM). RSM models of objective and constraint functions were generated using central composite (CCD) and D-optimal design. The accuracy of approximate models was evaluated through
value. The obtained optimal solutions by non-dominant sorting genetic algorithm (NSGA-II) were validated through the finite element analysis and we compared the obtained optimal solution by CCD and D-optimal design.
Microstructural Realization of SD400 Rebar by Developing Tempcore Simulation Apparatus
Park, Chun Su ; Yi, Hyang Jun ; Bae, Seh Wook ; Kim, Gil-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 5, 2015, Pages 543~547
DOI : 10.3795/KSME-A.2015.39.5.543
The cooling process referred to as Tempcore has been applied to produce a high-strength rebar. Excellent rebar with strength and weldability can be manufactured from mild steel without the addition of alloying elements by using the Tempcore process. However, there are limitations to evaluating the effect of various chemical compositions and cooling conditions within a site facility. In this study, we developed an apparatus to simulate the Tempcore process and obtained microstructures with a hardened surface layer, an intermediate region and a soft inner core. The experimental apparatus has been equipped with a cooler set that is the same as the site facility and consists of a pump line that supplies pressure of 12-13 bar and flow rate of up to
. In accordance with the simulation result of steel grade SD400 that requires more than 400 MPa of yield strength, both the hardened area ratio and the hardness with respect to each cooling depth were found to agree well with the product.