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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
Efficient Kinect Sensor-Based Reactive Path Planning Method for Autonomous Mobile Robots in Dynamic Environments
Tuvshinjargal, Doopalam ; Lee, Deok Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 549~559
DOI : 10.3795/KSME-A.2015.39.6.549
In this paper, an efficient dynamic reactive motion planning method for an autonomous vehicle in a dynamic environment is proposed. The purpose of the proposed method is to improve the robustness of autonomous robot motion planning capabilities within dynamic, uncertain environments by integrating a virtual plane-based reactive motion planning technique with a sensor fusion-based obstacle detection approach. The dynamic reactive motion planning method assumes a local observer in the virtual plane, which allows the effective transformation of complex dynamic planning problems into simple stationary ones proving the speed and orientation information between the robot and obstacles. In addition, the sensor fusion-based obstacle detection technique allows the pose estimation of moving obstacles using a Kinect sensor and sonar sensors, thus improving the accuracy and robustness of the reactive motion planning approach. The performance of the proposed method was demonstrated through not only simulation studies but also field experiments using multiple moving obstacles in hostile dynamic environments.
Optimization of the Operating Stiffness of a Two-Axis Parallel Robot
Lee, Jae-Wook ; Jang, Jin-Seok ; Lee, Sang-Kon ; Jeong, Myeong-Sik ; Cho, Yong-Jae ; Kim, Kun-Woo ; Yoo, Wan-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 561~566
DOI : 10.3795/KSME-A.2015.39.6.561
In this paper, the operating stiffness of a parallel robot used to handle heavy packages is optimized. Because the studied model, called a "pick and place robot," is applied for packaging logistics, it is important for the robot to be lightweight so that it may respond rapidly and have high stiffness to allow sufficient operating precision. However, these two requirements of low weight and high stiffness are mutually exclusive. Thus, the dynamic characteristics of the robot are analyzed through multibody dynamics analysis, and topology optimization is conducted to achieve this exclusive performance. Lastly, the reliability of the topology optimization is verified by applying the optimized design to the parallel robot.
Evaluation of Mechanical Properties of Carbon/Epoxy Composites Under In situ Low- and High-Temperature Environments
Im, JaeMoon ; Shin, KwangBok ; Hwang, Taekyung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 567~573
DOI : 10.3795/KSME-A.2015.39.6.567
This paper aims to evaluate the variation in the mechanical properties of carbon/epoxy composites under in situ low- and high-temperature environments. In situ low- and high-temperature environments were simulated with temperature ranging from
using an environmental chamber and furnace. The variation in the mechanical properties of the composites was measured for longitudinal and transverse tensile properties, in-plane shear properties and interlaminar shear strength. Under the low temperature of
, all mechanical properties increased moderately compared to the baseline properties measured at room temperature. The changes in the longitudinal tensile properties decreased moderately with increasing temperature. However, transverse tensile properties, in-plane shear properties and interlaminar shear strength each showed a significant drop due to the glass transition behavior of the matrix after
. Notably, the tensile property value near
increased compared to baseline property value, which was an unusual occurrence. This behavior was a direct result of post-curing of the epoxy resin due to its exposure to high temperature.
Evaluation of a Drill Bit Button Arrangement for Enhanced Drilling Efficiency
Kang, Hoon ; Cho, Jung Woo ; Jeong, Myeong Sik ; Cho, Yong Jae ; Lee, Sang Kon ; Lee, Jae Wook ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 575~581
DOI : 10.3795/KSME-A.2015.39.6.575
The drill bit, which directly transmits percussive forces and torque to the rock, is the core part of a rock drilling machine. For effective drilling, the button arrangement of a drill bit should be optimized because it is the most important design factor in determining drilling efficiency. Furthermore, a quantitative method is necessary to evaluate the button arrangement for the optimization of the drill bit button. Therefore, we propose a new method for the evaluation of the drill bit button arrangement using new evaluation indices, which include the overlapped impact area, blank area, and moment. Moreover, we verify the suitability of the proposed evaluation method by applying it to the conventional button arrangement.
Analysis of a Complete Contact Problem in Bonded Condition: Comparison of Experimental-Numerical Analyses and Theoretical Solutions
Kim, Hyung-Kyu ; Jang, Jae-Won ; Lee, Soon-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 583~588
DOI : 10.3795/KSME-A.2015.39.6.583
Asymptotic method has been often used to theoretically analyze the complete contact problem. The error of the asymptotic results increases as the distance from the contact edge increases. The singularity cannot be properly obtained from a finite element (FE) analysis owing to the finiteness of the element size. In the present work, the complete contact problem in bonded condition is analyzed using a combined experimental-numerical approach to assist and/or compare with the asymptotic results. Al and Cu alloys are used for the material combination of the punch and substrate. 120 and 135 degrees are used for the punch angle. The FE models are validated by comparison of displacement distributions obtained by the FE analysis and
experiment. Generalized stress intensity factors are evaluated using the validated FE models. Stress field in the vicinity of the sharp contact edges obtained from the FE and asymptotic analyses are compared. The discrepancies are also discussed.
Inclined Edge Crack in a Piezoelectric Material Under Antiplane Loads
Choi, Sung Ryul ; Sah, Jong Youb ; Jeong, Jae Tack ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 589~596
DOI : 10.3795/KSME-A.2015.39.6.589
The occurrence of an inclined edge crack in transversely piezoelectric material is analyzed. Concentrated antiplane mechanical and inplane electrical loads are applied at the boundary and crack surface, respectively. The crack surfaces are assumed to be impermeable to the electric field. Using the Mellin transform with the introduction of a generalized displacement vector, the problem is formulated, and the Wiener-Hopf equation is derived. By solving the equation, the solution is obtained in a closed form. The intensity factors of the stress, the electric displacement, and the energy release rate are obtained for any crack length and inclination angle. These solutions can be used as fundamental solutions and can be superimposed to represent any arbitrary electromechanical loading.
Effect of Nitriding on Fatigue Characteristics of Cr-Mo Alloy Steel
Oh, Kwang Keun ; Kim, Jae Hoon ; Choi, Hoon Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 597~602
DOI : 10.3795/KSME-A.2015.39.6.597
CrMo alloy steel was nitrided using two types of processing methods, ion-nitriding processing and nitrocarburizing. Both processes were conducted for a duration of 30 min. To compare the surface hardness of the alloys created by the different processes, microhardness tests were conducted, and fatigue tests of each material were performed by a cantilever rotary bending fatigue test machine (Yamamoto, YRB 200) in the very high cycle regime (
). Fractography of the fractured surfaces was conducted by scanning electron microscopy - to observe the fracture mechanisms of very high cycle fatigue and the effect of the nitriding process on the fatigue characteristics.
Posture and Space Recognition System Using Multimodal Sensors
Cha, Joo-Heon ; Kim, Si Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 603~610
DOI : 10.3795/KSME-A.2015.39.6.603
This paper presents a multimodal sensor system that can determine the location of house space by analyzing the postures and heights of the residents. It consists of two sensors: a tilt sensor and an altimeter sensor. The tilt sensor measures the static and dynamic postures of the residents, and the altimeter sensor measures their heights. The sensor system includes a Bluetooth transmitter, and the server receives the measured data and determines the location in the house. We describe the process determining the locations of the residents after analyzing their postures and behaviors from the measured data. We also demonstrate the usefulness of the proposed system by applying it to a real environment.
The System Position from High Firing Rate of Anti-Aircraft Gun system
Hwang, Boo Il ; Lee, Boo Hwan ; Kim, Chi Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 611~615
DOI : 10.3795/KSME-A.2015.39.6.611
Anti-aircraft gun system is used for low-level air defense system and has more than twin guns with high firing rate in order to maximize the capability of defense. Gun's vibration and bullet's variance has a critical effect on accuracy and hit probability of weapon system such as anti-aircraft gun system with high firing rate. Typical mechanism to reduce the amount of vibration and shock during gun-fire process is very important design factor. In this paper, the suspension characteristics of the vehicle are studied for the improvement of isolating performance of gun firing system with high firing rate. Gun fire test for the vehicle is conducted and computational models using Recurdyn and Adams are created based on test results. Through this study, results of computational analysis are compared with the real test results, which includes type, location and quantity of suspension and gun mechanism are selected for anti-aircraft gun. From the result of this study, we could make basic design and consider the proper component of the system such as suspension and gun spring.
Development of Elbow Wearable Robot for Elderly Workers
Lee, Seok-Hoon ; Lee, Si-Haeng ; Kim, Jung-Yup ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 617~624
DOI : 10.3795/KSME-A.2015.39.6.617
This paper describes the development of a wearable robot to assist the elbow muscle for use by elderly workers in aging societies. Various previously developed wearable robots have drawbacks in terms of their price, portability, and slow recognition of the wearer's intention. In this paper, emphasis is placed on the following features to minimize these drawbacks. The first feature is that an actuator is attached only at the elbow joint that withstands the highest moment during arm motion to reduce the weight, volume, and price of the robot and increase its practicality. The second is that operation of the wearable robot is divided into two modes, a tracking mode and a muscle strengthening mode, and the robot can automatically switch between these modes by analyzing the wearer's intention through the brachial muscle strength measuring device developed in this study. The assistive performance of the developed wearable robot is experimentally verified by motion tracking experiments without an external load and muscle strengthening experiments with an external load. During the muscle strengthening experiments, the power of the muscle of the upper arm is measured by a commercial electromyography (EMG) sensor. Motion tracking performance at a speed of
and muscle assistance of over 60 % were obtained using our robot.
Prognostics for Stator Windings of Water-Cooled Generator Against Water Absorption
Jang, Beom Chan ; Youn, Byeng D. ; Kim, Hee Soo ; Bae, Yong Chae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 625~629
DOI : 10.3795/KSME-A.2015.39.6.625
In this study, we develop a prognostic method of assessing the stator windings of power generators against water absorption through statistical data analysis and degradation modeling. The 42 windings of the generator are divided into two groups: the absorption and normal groups. A degradation model of a winding is constructed using Fick's second law to predict the level of absorption. By analyzing data from the normal group, we can determine the distribution of the data of normal windings. The health index of a winding is estimated using the directional Mahalanobis distance (DMD) method. Finally, the probability distributions of the failure time of the windings are determined.
Semiquantitative Failure Mode, Effect and Criticality Analysis for Reliability Analysis of Solid Rocket Propulsion System
Moon, Keun Hwan ; Kim, Jin Kon ; Choi, Joo Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 631~638
DOI : 10.3795/KSME-A.2015.39.6.631
In this study, semiquantitative failure mode, effects, and criticality analysis (FMECA) for the reliability analysis of a solid rocket propulsion system is performed. The semiquantitative FMECA is composed of failure mode and effects analysis (FMEA) and criticality analysis (CA). To perform FMECA, the structure of the solid rocket propulsion system is divided into 43 parts down to the component level, and FMEA is conducted at the design stage considering 137 potential failure modes. CA is then conducted for each failure mode, during which the criticality number is estimated using the failure rate databases. The results demonstrate the relationship between potential failure modes, causes, and effects, and their risk priorities are evaluated qualitatively. Additionally, several failure modes with higher criticality and severity values are selected for high-priority improvement.
Effect of Center Pin in Free Fall Test for a Cylindrical Li-ion Cell
Kim, Simon ; Lee, Young Shin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 6, 2015, Pages 639~644
DOI : 10.3795/KSME-A.2015.39.6.639
A cylindrical secondary Li-ion cell is a device in which stored chemical energy is converted to electrical energy via an electrochemical reaction. These cells are widely used for applications that require high capacity and rate power, such as notebooks, power tools, and electric vehicles. The role of a center pin is to retain the channel for gas release, preventing blockage of the hollow of the jelly roll during a charge-discharge cycle, and to prevent an internal short circuit for tearing of separator under mechanical free fall. In this paper, two experiments are conducted with and without the center pin to experimentally verify the importance of the role of the center pin. The first experiment is a 50-cycle charge-discharge cycle test, and the second is a free fall test conducted according to the Underwriters Laboratories (UL) standards. Based on these experiments, we demonstrate that the center pin in a cylindrical cell is a very important component in terms of safety.