• Structural Engineering and Mechanics
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• v.76 no.2
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• pp.207-222
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• 2020

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train subjected to fluctuating crosswind. To ensure the safe operation in metro lines in mountain cities, running safety of the metro train over the high-pier bridge under crosswind is analyzed in this paper. Firstly, the dynamic model of the wind-train-bridge (WTB) system is built, in which the speed-up effect of crosswind is fully considered. On the basis of time domain analysis, the basic characteristics of the WTB system with high-pier are analyzed. Afterwards, the dynamic responses varies with train speed and wind speed are calculated, and the safety zone of metro train over a high-pier bridge subjected to fluctuating crosswind in mountain city is determined. The results indicate that, fluctuating crosswind triggers drastic vibration to the metro train and high-pier bridges, which in turn causes running instability of the train. For this reason, the corresponding safety zone for metro train running on the high-pier is proposed, and the metro traffic on the high-pier bridge should be closed as the mean wind speed of standard height reaches 9 m/s (15.6 m/s for the train).

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.145-150
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• 2005

This paper presents an Electrotactile Display System (ETCS). One of the most important human sensory systems for human computer interaction is the sense of touch, which can be displayed to human through tactile output devices. To realize the sense of touch, electrotactile display produces controlled, localized touch sensation on the skin by passing small electric current. In electrotactile stimulation, the mechanoreceptors in the skin may be stimulated individually in order to display the sense of vibration, touch, itch, tingle, pressure etc. on the finger, palm, arm or any suitable location of the body by using appropriate electrodes and waveforms. We developed an ETCS and investigated effectiveness of the proposed system in terms of the perception of roughness of a surface by stimulating the palmar side of hand with different waveforms and the perception of direction and location information through forearm. Positive and negative pulse trains were tested with different current intensities and electrode switching times on the forearm or finger of the user with an electrode-embedded armband in order to investigate how subjects recognize displayed patterns and directions of stimulation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.1-7
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• 2015

Cleaning by injecting dry ice and water is a generally adopted trend these days to clean molds (injection, diecasting foundry, press, rubber mold, etc). This cleaning method is performed manually, or by installing multiple high pressure spray nozzles. We have manufactured a turbine cleaning module device that is able to clean diecasting modules at any position and angle in the space by mounting an articulated robot instead of the existing pipe type injection nozzle, to minimize lead time and enhance working yield of the cleaning process. In this paper, we analyzed process factors that are required to design the turbine module by reviewing number of revolution, and results according to different blade angles and thicknesses of the mold release injection turbine module, using computational fiuid dynamics (CFD).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.6
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• pp.95-100
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• 2016

We suggest and simulate an optical filter that a red wavelength range cannot transmit to protect the psychological stress that originates from the cognition of red color in emergency medical technicians. When a nanohole hexagonal array is fabricated on gold film using Anodic Aluminum Oxide (AAO), the blocked wavelength can be tuned by the hole diameter and film thickness. The characteristic of the transmittance for normal incident white light is simulated with Finite Element Method (FEM) in the MATLAB platform. Although the transmittance of the overall wavelength is reduced by 50% by the gold film, the transmittance of the red wavelength range is decreased by over 87%.

• Journal of Mechanical Science and Technology
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• v.19 no.4
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• pp.968-975
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• 2005

The shearing process for the sheet metal is normally used in the precision elements such as semi-conductor components. In these precision elements, the burr formation brings a bad effect on the system assembly and demands the additional de-burring process, so this imposes high cost on manufacturing. In this paper, we have developed the in-situ auto-aligning precision meso-punching system to investigate the burr formation mechanism and ultimately minimize burr. Firstly, we introduced the punch-die contact sensing method to align the punch and the die at initial state prior to the punching process. Secondly, by using the low-price semi-con­ductor laser, burr formed on the edges is measured intermittently during the punching process. We could, finally, make burr on the sheet metal uniformized and minimized by controlling of the precision X - Y table, $1\;{\mu}m$ resolution, and measuring burr height by semiconductor laser. Experimental results show the validity of our system for pursuing the burr-free punched elements.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.813-820
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• 2014

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.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.909-913
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• 2013

Various types of large substrate handling robots are used in the thin file solar cell manufacturing line as well as LCD or PDP production line. Because the robot handles the heavy substrate at high speed, there are some issues such as vibration control and the optimal design of arms and forks. As the substrate becomes larger and heavier, robot systems are also larger and the vibration issue of the robot end-effector becomes more important. In the paper, we established the robot modeling and the control architecture including the flexible part such as forks. Then, we performed dynamic simulation in the various condition and analyzed the characteristics of the fork vibration. We can reduce the vibration using the trajectory planning and input shaping algorithm and it was proved by experiment.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.923-930
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• 2013

These days, the interests on the high speed handling robots are increasing because it is important to get down the unit cost of production to get the price competitiveness. The parallel kinematic mechanism is more suitable to implement the high speed robot system as well known. The moving parts of the high speed parallel robot have to be designed for light weight. But the vibration motion is induced by the light weight links because they drive in high acceleration and deceleration. In this reason, the structural analysis of the high speed parallel kinematic robot is very important in the design process. In this paper, the study on the structural analysis of a high speed parallel robot has been done and the research results will be introduced.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.2
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• pp.186-193
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• 2014

This paper presents characteristic analysis of underwater bearing for canned type electric water pump. Characteristic analysis of underwater bearing was performed using self-developed performance tester, which capable of torque change, noise change, motor speed change and abrasion loss test with respect to temperature change of underwater bearing. The performance tester can be monitored in real time by designing the control unit using the Labview program. The performance experiment was performed through comparison of the silicon carbide (SIC) and the carbon bearing. From the experiment results, performance of SIC bearing was better than carbon bearing at the abrasion and temperature experiment.

• Journal of the Semiconductor & Display Technology
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• v.12 no.4
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• pp.39-44
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• 2013

In the semiconductor heat-treatment process, the temperature uniformity determines the film quality of a wafer. This film quality effects on the overall yield rate. The heat transfer of the wafer surface in the heat-treatment process equipment is occurred by convection and radiation complexly. Because of this, there is the nonlinearity between the wafer temperature and reactor. Therefore, the accurate prediction of temperature on the wafer surface is difficult without the direct measurement. The thermal camera and the T/C wafer are general ways to confirm the temperature uniformity on the heat-treatment process. As above ways have limit to measure the temperature in the precise domain under the micro-scale. In this study, we developed the thin film type temperature sensor using the MEMS technology to establish the system which can measure the temperature under the micro-scale. We combined the experiment and numerical analysis to verify and calibrate the system. Finally, we measured the temperature on the wafer surface on the semiconductor process using the developed system, and confirmed the temperature variation by comparison with the commercial T/C wafer.