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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 31, Issue 12 - Dec 2014
Volume 31, Issue 11 - Nov 2014
Volume 31, Issue 10 - Oct 2014
Volume 31, Issue 9 - Sep 2014
Volume 31, Issue 8 - Aug 2014
Volume 31, Issue 7 - Jul 2014
Volume 31, Issue 6 - Jun 2014
Volume 31, Issue 5 - May 2014
Volume 31, Issue 4 - Apr 2014
Volume 31, Issue 3 - Mar 2014
Volume 31, Issue 2 - Feb 2014
Volume 31, Issue 1 - Jan 2014
Selecting the target year
Wheelset Steering Control for Improvement a Running Safety on Curved Track
Hur, Hyun Moo ; Ahn, Da Hoon ; Kim, Nam Po ; Sim, Kyung Seok ; Park, Tae Won ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 759~764
DOI : 10.7736/KSPE.2014.31.9.759
Lateral force of wheel is important parameter when we evaluate the safety of a railway vehicle on curved track. The lateral force of wheel is influenced by the steering performance of wheelsets. Generally, in passive type vehicles, the steering performance of wheelsets is influenced by the parameters like primary spring stiffness, wheel base, conicity of the wheel profile, etc. But, the steering performance of passive type vehicle has its limit. To overcome the limit of the steering performance of passive type vehicle, active steering technology is being developed. In this paper, we analyze the lateral force of wheel and the safety of the railway vehicle on curved track by adopting the active steering technology. As results of dynamic analysis for vehicle model equipped with active steering system, the lateral force of wheel is reduced and the safety is improved remarkably.
Study on Reduction Method and Characteristic of Lateral Vibration of the Tail Car in a High Speed Train
Kim, Jae Chul ; Kwon, Seok Jin ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 765~771
DOI : 10.7736/KSPE.2014.31.9.765
During the acceptance test of KTX, unexpectedly great lateral vibration in 14th~16th train at 150km/h~200km/h was appeared on a straight line in the winter season. Generally, stiffness of secondary suspension in KTX vehicle is one of the most sensitive components on air temperature. So, we examined that the secondary suspension to be mounted heating system was able to reduce the lateral vibration in the tail car of KTX. Also, we verified that lateral vibration from test results on KTX train with wheel conicity 1/20 disappeared. In this paper, we analysis effective reduction methods and the cause of the lateral vibration using model of KTX train and compare with the test results. The analysis results agree well with test ones. From mode analysis result, lateral vibration is occurred at natural frequency range 0.5~0.6Hz with a negative damping value and its natural frequency disappear gradually according to increasing of wheel concinicy.
A Study on Appropriate Driving Speed for High-Speed Trains Running the Conventional Line
Ham, Young Sam ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 773~776
DOI : 10.7736/KSPE.2014.31.9.773
KTX (Korea Train eXpress) is the first high-speed train operated in Korea and its highest speed reaches 300 km/h. Korean high-speed trains are mostly operated on the railroads exclusively designed for high-speed trains, but the sections of Seoul~Gwangmyeong, nearby of Daejeon station and Dongdaegu are operated on the existing tracks having the speed less than 150 km/h. With this paper, we'd like to analyze the lateral force that occurs between the wheels and the rail when high-speed trains were operated on the existing track section to suggest an appropriate driving speed for high-speed trains. As the rigid wheel base of the high-speed train is 3m which is about 50% longer than normal vehicles, it works as an advantage for high-speed driving. However, as the lateral force becomes higher than normal vehicles when driving on curves, plans to reduce wear-outs on the wheels are required.
Evaluation of Non Destructive Inspection Interval for Running Safety of Railway Axle
Kwon, Seok Jin ; Lee, Dong Hyung ; Seo, Jung Won ; Kim, Jae Chul ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 777~782
DOI : 10.7736/KSPE.2014.31.9.777
Usually, railway axles are designed for infinite life based on endurance limit of the material and the axle is not fractured immediately when a surface crack initiated. The railway axles have been inspected regularly by NDT such as ultrasonic testing, magnetic testing and eddy current testing and so on. Because the axle failure is profoundly influenced by the probability of missing a fatigue crack during an NDT inspection, it is necessary to evaluate the Non Destructive Interval of railway axle. In the present paper, the Non Destructive Interval of railway axle based on fracture mechanics and finite element analysis was investigated. It was shown that the Non Destructive Interval of railway axle can be evaluated using fracture mechanics approach and extended using NDT which a crack can detect clearly.
Evaluation of Mechanical Characteristic and Residual Stress for Railway Wheel
Seo, Jung Won ; Kwon, Suk Jin ; Lee, Dong Hyeong ; Jun, Hong Kyu ; Park, Chan Kyeong ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 783~790
DOI : 10.7736/KSPE.2014.31.9.783
Railway wheels and axles are the most critical parts of the railway rolling stock. The wheel carry axle loads and guide the vehicles on the track. Therefore, the contact surface of wheel are subjected to wear and fatigue process. The wheel damage can be divided into three types; wear, contact fatigue failure and thermal crack due to braking. Therefore, in the contact surface between the wheel and the rail, the materials are heat treated to have a specific hardness. The manufacturing quality of the wheel have a considerable influence on the formation of tread wear and damage. Also, the residual stress on wheel is formed during the manufacturing process is one of the main sources of the damage. In this paper, the mechanical characteristic and the residual stress according to wheel material have been evaluated by applying finite element analysis and conducting mechanical tests.
Fabrication of Blended PCL/β-TCP Scaffolds by Mixture Ratio of β-TCP using Polymer Deposition System
Ha, Seong-Woo ; Kim, Jong Young ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 791~797
DOI : 10.7736/KSPE.2014.31.9.791
Abstract Scaffold used as a carrier of the cell has been actively conducted using plenty of technology in tissue engineering.
-tricalcium phosphate (
-TCP) material has shown good biocompatibility and osteoconductive ability when it was implanted as a bone graft substitute in osseous defect in human and animal studies for bone regeneration. In this study, we fabricated the blended polycaprolactone (PCL) and
-TCP scaffold by the polymer deposition system (PDS). The PCL/
-TCP scaffold was fabricated at a temperature of
, pressure of 650 kPa, and scan velocity of 100 mm/sec. The Overall geometry and size of the scaffold were fixed circle type with a diameter of 10 mm and a height of 4 mm. PCL/
-TCP scaffold was observed by scanning electron microscopy. Cell attachment and proliferation of the scaffold containing 30 wt%
-TCP was superior to those containing 10 wt% and 20 wt%
Wear Characteristics of CBN Tools on Hard Turning of AISI 4140
Yang, Gi-Dong ; Park, Kyung-Hee ; Lee, Myung-Gyu ; Lee, Dong Yoon ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 799~804
DOI : 10.7736/KSPE.2014.31.9.799
Hard turning is a machining process for hardened materials with high surface quality so that grinding process can be eliminated. Therefore, the hard turning is capable of reducing machining time and improving productivity. In this study, hardened AISI4140 (high-carbon chromium steel) that has excellent yield strength, toughness and wear resistance was finish turned using CBN tools. Wear characteristics of CBN tool was analyzed in dry and MQL mixed with nano-particle (Nano-MQL). The dominant fracture mechanism of CBN tool is diffusion and dissolution wear on the rake surface resulting in thinner cutting edge. Abrasive wear by hard inclusion in AISI4140 was dominant on the flank surface. Nano-MQL reduced tool wear comparing with the dry machining but chip evacuation should be considered. A cryogenically treated tool showed promising result in tool wear.
A Simple Yb-Doped Mode-Locked Fiber Oscillator under Normal Dispersion as a Seed Laser
Kim, Byeong Kwon ; Joo, Ki-Nam ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 805~811
DOI : 10.7736/KSPE.2014.31.9.805
In this investigation, we constructed and demonstrated a simple Yb-doped fiber laser, of which longitudinal modes are mode-locked without any additional devices to compensate the dispersion caused by optical components. Non-linear polarization rotation (NPR) was adopted for the mode-locking mechanism and a polarization controller (PC) was used for a kind of spectral filters to restrict the bandwidth for mode-locking. As the result, the laser was successfully operated as mode-locked with the repetition rate of 42.2 MHz and the spectrum was broadened up to approximately 16 nm at 1033 nm center wavelength when the laser was mode-locked. In this paper, the operation of the developed Yb-doped mode-locked laser is explained with the concept of Lyot filter realized by a PC, which enables mode-locking under normal dispersion. In the industrial applications, this laser can be used as a seed laser of the high power lasers for optical manufacturing.
Design of the Step-stare Image Gathering System for an Aerial Reconnaissance
Baek, Woonhyuk ; Park, Jaeyoung ; Ahn, Junghun ; Lee, Jungsuk ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 813~820
DOI : 10.7736/KSPE.2014.31.9.813
This paper presents design and performance validation of a method for motion compensation using fast steering mirror. First of all, the schematics of the Electro Optical/Infra-Red (EO/IR) and step-stare image gathering system for an aerial reconnaissance are introduced. Because of the steering mirror with low inertia so called Back scan mechanism (BSM), the fast step-stare image gathering technique that is required for taking a high-definition still image will be realized. After then, the BSM hardware includes motors and feedback sensors are introduced. Also, the motion profile for BSM will be designed to compensate roll scan motion of the gimbals. At the end of this paper, designed profile and tracking performance of the EO/IR system with BSM will be validated through experiments.
Design of Controller and Gripper for Wireless Communication of Gripper Contact Signal
Kim, Hyeon Min ; Kim, Chong Jin ; Kim, Gab Soon ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 821~829
DOI : 10.7736/KSPE.2014.31.9.821
This paper describes the development of a wireless communication controller of gripper contact signal for industrial robot. The wireless communication gripper controller is composed of a robot wireless communication controller and a gripper wireless transmitting/receiving controller. The robot wireless communication controller transmits the data of gripper sensors, and the gripper wireless communication controller receives the data. And the controller sends the data to the robot controller of industrial robot. As a result of the characteristics test of the wireless communication gripper controller, it is thought that the robot wireless communication controller A transmits and receives three gripper wireless transmitting/receiving controller A1, A2, A3 another. Thus, the developed wireless communication gripper controller can be used for transmitting/ receiving the data of gripper sensors for industrial robot.
Relationship between Contrast Ratio of Conductive Particle and Contact Resistance on COG Bonding using ACF
Jin, Songwan ; Jeong, Young Hun ; Choi, Eun Soo ; Kim, Bosun ; Yun, Won-Soo ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 831~838
DOI : 10.7736/KSPE.2014.31.9.831
Chip on glass (COG) bonding using anisotropic conductive film (ACF) is a key technology to assemble a driver IC onto a LCD glass panel. In this paper, an experimental investigation was conducted to investigate the correlation between contact resistance and characteristics of image taken by machine vision based inspection system. The results show that the contact resistance was strongly influenced by the contrast ratio of conductive particle rather than the number of conductive particles. Also, number of conductive particles whose contrast ratio is below 0.75 is crucial for determining the quality of the assembled samples. On the other hand, in the result of high temperature high humidity storage test, the contrast ratio of samples was increased. However, in the case of open-circuit samples after temperature humidity storage test, the number of conductive particles whose contrast ratio is above 0.75 was more than that of the closed-circuit samples.
Evaluation of Clamping Characteristics for Subminiature Screws According to Thread Angle Variation
Min, Kyeong Bin ; Kim, Jong Bong ; Park, Keun ; Ra, Seung Woo ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 839~846
DOI : 10.7736/KSPE.2014.31.9.839
Recent trends in the miniaturization and weight reduction of portable electronic parts have driven the use of subminiature screws with a micrometer-scale pitch. As both screw length and pitch decrease in subminiature screws, the resulting clamping force becomes diminishes. In this work, Finite element (FE) analysis is performed to evaluate clamping force of a screw assembly, with a comparison with experimental result. To improve clamping force of subminiature screws, a new screw design is considered by modifying screw thread angle: the thread angle is varied as an asymmetric way unlike the conventional symmetric thread angle. FE analyses are then performed to compare the clamping characteristics of each subminiature screw with different thread angle. The effect of thread angles on the clamping force is then discussed in terms of structural safety for both positive and negative screws.
A Study on the Early Fire Detection based on Environmental Characteristics inside the Nacelle of Wind Turbine Generator System
Kim, Da Hee ; Lim, Jong Hwan ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 9, 2014, Pages 847~854
DOI : 10.7736/KSPE.2014.31.9.847
The paper presented a method of early fire detection based on the environmental characteristics inside the nacelle of wind turbine generator system(WTGS). The rising rates of the temperature and smoke density were used as the parameters for early fire detection. By considering the characteristics of temperature and smoke density of a nacelle, this method is very reliable and can minimize the possibility of a malfunction of fire detection. The performance of the method was tested through sets of experiments by using nacelle simulator.