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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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Accelerated Life Testing and Validity Evaluation of Finger Strips Used for Electromagnetic Shielding Doors
Lee, Joo Hong ; Kim, Do Sik ; Chang, Mu Seong ; Cho, Hae Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 831~837
DOI : 10.3795/KSME-A.2015.39.9.831
Many persons and electronic devices are exposed to electromagnetic (EM) waves generated from magnetic resonance imaging (MRI) equipment, EM pulses (EMPs), and many other kinds of EM wave devices. Finger strips are used to provide shielding from these EM waves. Because of the high thermal conductivity of finger strips, they are used in the design of specialized doors that are installed in shielded rooms. In this study, we perform an accelerated life test using the load acceleration stress, which affects the main failure mode of finger strips. We predict the life of the finger strip under normal usage conditions based on the results of the accelerated life test. We compare the results with those predicted from the life test under normal usage conditions to evaluate the validity of accelerated life testing.
Monitoring Machining Conditions by Analyzing Cutting-Force Vibration
Piao, Chunguang ; Kim, Ju Wan ; Kim, Jin Oh ; Shin, Yoan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 839~849
DOI : 10.3795/KSME-A.2015.39.9.839
This paper deals with an experimental technique for monitoring machining conditions by analyzing cutting-force vibration measured at a milling machine. This technique is based on the relationship of the cutting-force vibrations with the feed rate and cutting depth as reported earlier. The measurement system consists of dynamic force transducers and a signal amplifier. The analysis system includes an oscilloscope and a computer with a LabVIEW program. Experiments were carried out at various feed rates and cutting depths, while the rotating speed was kept constant. The magnitude of the cutting force vibration component corresponding to the number of cutting edges multiplied by the frequency of rotation was linearly correlated with the machining conditions. When one condition of machining is known, another condition can be identified by analyzing the cutting-force vibration.
Estimation of Transient Creep C(t)-integrals for SE(B) Specimen Under Elastic-Plastic-Creep Conditions
Lee, Han-Sang ; Je, Jin-Ho ; Kim, Dong-Jun ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 851~857
DOI : 10.3795/KSME-A.2015.39.9.851
In this paper, we estimate the time-dependent C(t) integrals under elastic-plastic-creep conditions. Finite-element (FE) transient creep analyses have been performed for single-edge-notched-bend (SEB) specimens. We investigate the effect of the initial plasticity on the transient creep by systematically varying the magnitude of the initial step load. We consider both the same stress exponent and different stress exponents in the power-law creep and plasticity to elastic-plastic-creep behavior. To estimate the C(t) integrals, we compare the FE analysis results with those obtained using formulas. In this paper, we propose a modified equation to predict the C(t) integrals for the case of creep exponents that are different from the plastic exponent.
A Permeable Wedge Crack in a Piezoelectric Material Under Antiplane Deformation
Choi, Sung Ryul ; Park, Jai Hak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 859~869
DOI : 10.3795/KSME-A.2015.39.9.859
In this study, we analyze the problem of wedge cracks, which are geometrically unsymmetrical in transversely piezoelectric materials. A single concentrated antiplane mechanical load and inplane electrical load are applied at the point of the wedge surface, while one concentrated antiplane load is applied at the crack surface. The crack surfaces are considered as permeable thin slits, where both the normal component of electric displacement and the electric potential are assumed to be continuous across these slits. Using Mellin transform method, 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 and the electric displacement are obtained for any crack length as well as inclined and wedge angles. Based on the results, the intensity factors are independent of the applied electric loads. The electric displacement intensity factor is always dependent on that of stress intensity factor, while the electric field intensity factor is zero. In addition, the energy release rate is computed. These solutions can be used as fundamental solutions which can be superposed to arbitrary electromechanical loadings.
Development of Test Equipment for Complex Underwater Environments
Kim, Jong Cheol ; Lee, Gi Chun ; Choi, Byung Oh ; Jung, Dong Soo ; Lee, Choong Sung ; Jeon, Jun Wan ; Lee, Jae Ho ; Hwang, Kyung Ha ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 871~877
DOI : 10.3795/KSME-A.2015.39.9.871
Deep-sea equipment such as underwater robots and unmanned submersible vehicles, include various machine components and sensors, and it is important that their reliabilities be tested before use in the fields. This is necessary because they are affected by complex extreme-environment conditions, such as high pressures, extreme temperatures, and tidal forces that are present in the deep sea. We require test equipment that can conduct empirical tests in conditions that mimic these complex oceanic environments. In this study, we propose specifications that should be met, and a design plan for the primary components, which should limit their use to a maximum water pressure of 2.0 MPa, water temperature of
, and a maximum flow velocity of 2 m/s. in work-in type underwater combined environment test equipment and. We present test system development procedures to verify the reliability of products and systems used in deep-sea environments.
Lateral Position Measurement System for Precision Alignment of Roll-to-Roll Printing Using Alignment Patterns and Quantity of Light
Jung, Minkyu ; Kim, Hyungi ; Oh, Dongho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 879~884
DOI : 10.3795/KSME-A.2015.39.9.879
Printed electronics is a technology that produces electronic devices and circuits by printing functional ink on a web, which is a film-like flexible material. This technology is suitable for large-scale and high-speed mass production, and is a next-generation process technology that can fabricate electronic devices from flexible materials. As precise measurement of the positions of the web is required in order to commercialize such a printed electronics process, a measurement system with an optical encoder with a precision of micrometers had been proposed in the preceding research of this study. However, the lateral positions of the web could not be measured in the preceding research as the phenomenon of the entire web being moved in the lateral direction could not be detected. In this study, a measurement system that utilizes the differences in the amount of light reflected from the alignment patterns depending on the web positions in the lateral direction was proposed for measuring the lateral positions of the web. In addition, its reliability was verified and then the effect when measuring printed alignment patterns was analyzed by experiments.
Study on Computational Simulation of a Metro Collision Accident and Improvement of Passive Safety
Jung, Hyun Seung ; Son, Seung Wan ; Kwon, Tae Soo ; Kim, Jin Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 885~892
DOI : 10.3795/KSME-A.2015.39.9.885
In this study, we simulate the railway crash accident that occurred at the Sangwangsimni station on the Seoul Metro Line #2, and we propose a solution to minimize the damage. We use LS-DYNA, which is the commercial software employed for collision analysis to perform 1-D and 3-D simulations for the recurrence of accidents. By performing 1-D simulations, we analyze the load, displacement, absorbed energy of the couplers, and acceleration of vehicles, and we evaluate the safety in accidental collisions. By performing 3-D simulations, we analyze the deformation of the car and over-ridding. We propose methods to improve the safety in collisions involving railway vehicles, and we perform collision accident simulations to determine improvements when applying a high-performance energy absorber to the front car.
Deformation Analysis Considering Thermal Expansion of Injection Mold
Kim, Jun Hyung ; Yi, Dae-Eun ; Jang, Jeong Hui ; Lee, Min Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 893~899
DOI : 10.3795/KSME-A.2015.39.9.893
In the design of injection molds, the temperature distribution and deformation of the mold is one of the most important parameters that affect the flow characteristics, flash generation, and surface appearance, etc. Plastic injection analyses have been carried out to predict the temperature distribution of the mold and the pressure distribution on the cavity surface. As the input loads, we transfer the temperature and pressure results to the structural analysis. We compare the structural analysis results with the thermal expansion effect using the actual flash and step size of a smartphone cover part. To reduce the flash problem, we proposed a new mold design, and verified the results by performing simulations.
Weibull Statistical Analysis on Mechanical Properties in ZrO
with SiC Additive
Nam, Ki Woo ; Kim, Seon Jin ; Kim, Dae Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 901~907
DOI : 10.3795/KSME-A.2015.39.9.901
The Vickers hardness test is a common method used to characterize the hardness of ceramic materials. However, the hardness is not a deterministic value, but is a random variable. The objective of this paper is to investigate the statistical properties of the bending strength and a set of Vickers hardness values in single
with a SiC additive. In this work, we compare the characteristic value and variation with the results based on Weibull statistical analysis. The probability distributions of the bending strength and Vickers hardness agreed relatively well with the Weibull distribution. We evaluate the scale parameter and shape parameter in asreceived
composite ceramics, as well as in their heat treated ceramics.
Study of Behavior Characteristics of Impinging Spray of Emulsified Fuel
Yeom, Jeong Kuk ; Kim, Hak Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 909~916
DOI : 10.3795/KSME-A.2015.39.9.909
In this study, to investigate the effect of spray behavior characteristics, we induce the mixing ratio of emulsified fuel using impinging spray. We formulate the emulsified fuel by mixing diesel and hydrogen peroxide(
). We set the temperature of the heating plate to
, and set the injection pressures to 400, 600, 800, and 1000bar. The surfactants for the emulsified fuel mixture, which were mixed span80 and tween80 was mixed as 9:1, were fixed to 3% of the total volume of the emulsified fuel. We set the mixing ratio of
in the emulsified fuel as emulsified fuel(EF)0, EF2, EF12, and EF22. Further, we visualize the evaporation impinging spray using the Schlieren method. Based on the results of this study, we found that a higher temperature and injection pressure of the heating plate impingement led to the active diffusion of the fuel vapor, which promoted emulsified fuel evaporation. When the emulsified fuel is utilized in an actual engine, because of the temperature-drop effect of the combustion chamber, which is due to the evaporation of
in fuel and faster mixture formation is expected to decrease the engine emissions.
Basic Study of Evaporative Characteristics of Emulsified Fuels
Yeom, Jeong Kuk ; Yoon, Jeong Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 917~922
DOI : 10.3795/KSME-A.2015.39.9.917
The goal of this study is to consider the application of alternative blended fuel to diesel engine. In this study, as the test fuels, we use a blended fuel mix of diesel and hydrogen peroxide. As the primary variable, we vary the mixing ratio of diesel and hydrogen peroxide in the experimental and numerical analysis. We perform an evaporative behavior characteristics analysis of the emulsified fuel using the Schlieren method. The numerical analysis was carried out based on results obtained from the experimental analysis using the commercial code(ANSYS CFX). Consequently, we found that the micro-explosion depends on the fraction of hydrogen peroxide, and we propose a numerical method for the quantitative evaporation analysis of emulsified fuel droplets using the calculation of the volume fraction in the oil domain.
Experimental Verification of Characteristics of Magnetic Abrasive Polishing Combined with Ultrasonic Vibration
Jin, Dong-Hyun ; Kwak, Jae-Seob ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 923~928
DOI : 10.3795/KSME-A.2015.39.9.923
In this paper, we propose an ultrasonic magnetic abrasive polishing (US-MAP) technique to effectively machine a high-strength material, and we prove the efficiency of hybrid finishing. We use Taguchi's experimental method to determine the influence of each parameter. Based on the results, US-MAP exhibited a higher polishing efficiency than traditional MAP, and a suitable frequency for hybrid finishing was 28 kHz. When investigating the effect of the parameters on the surface roughness, the ultrasonic amplitude had the greatest effect. However, when machining with
amplitude, the machining efficiency decreased as the magnetic flux density varied.
Derivation of Nacelle Transfer Function Using LiDAR Measurement
Kim, Hyun-Goo ; Kang, Yong-Heack ; Yun, Chang-Yeol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 929~936
DOI : 10.3795/KSME-A.2015.39.9.929
Nacelle anemometers are mounted on wind-turbine nacelles behind blade roots to measure the free-stream wind speed projected onto the wind turbine for control purposes. However, nacelle anemometers measure the transformed wind speed that is due to the wake effect caused by the blades' rotation and the nacelle geometry, etc. In this paper, we derive the Nacelle Transfer Function (NTF) to calibrate the nacelle wind speed to the free-stream wind speed, as required to carry out the performance test of wind turbines according to the IEC 61400-12-2 Wind-Turbine Standard. For the reference free-stream wind data, we use the Light Detection And Ranging (LiDAR) measurement at the Shinan wind power plant located on the Bigeumdo Island shoreline. To improve the simple linear regression NTF, we derive the multiple nonlinear regression NTF. The standard error of the wind speed was found to have decreased by a factor of 9.4, whereas the mean of the power-output residual distribution decreased by 6.5 when the 2-parameter NTF was used instead of the 1-parameter NTF.
Study on the Optimized Condition of the Slot-Die Coating Process
Seo, Eung Soo ; Ye, Jungwoo ; Hwang, Joong Kook ; Shim, Jaesool ; Chai, Young Suck ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 937~945
DOI : 10.3795/KSME-A.2015.39.9.937
In this paper, we study the coating performance according to the slot-die conditions in the coating process. The quality of the slot-die coating depends on factors such as feeding speed of film, the viscosity of liquid, and the pressure applied to the slot-die. In this study, we determine the optimum conditions for a stable coating by performing 2-D and 3-D simulations. We carry out numerical simulations with respect to the feeding velocity of the film, the pressure of the slot-die inlet, and the viscosity of the coating liquid. Based on the results, the coating was the most reliable when the pressure of the inlet was
, the viscosity was about 100 cps and the velocity was 20 m/min.
Performance Improvement of Hot-Air Dryer Through Optimum Round-Hole Plate
Seo, Eung Soo ; Kim, Yongsik ; Hwang, Joong Kook ; Chai, Young Suck ; Shim, Jaesool ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 9, 2015, Pages 947~954
DOI : 10.3795/KSME-A.2015.39.9.947
The homogeneous coating of a flexible film that is applied to dye-sensitized solar cells is related to the performance and durability of the product. The applied coating is obtained from the uniform temperature distribution and the mass flow rate in the nozzle of the hot air dryer. In this study, we determine the uniform temperature distribution and mass flow rate of each nozzle by performing numerical simulations to understand how various factors affect the performance of the hot air dryer. The numerical model is composed of the momentum equation for flow motion and the energy equation for temperature. In addition, we compare the numerical results to the experimental results to validate the model. Based on the results, the round-hole plate inside the hot air dryer significantly affects the uniform temperature and the mass flow rate.