• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.7
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• pp.569-573
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• 2012

We investigated the speed change of the diamond spherical abrasive during the substrate surface polishing under the pad compression by using classical molecular dynamics modeling. We performed three-dimensional molecular dynamics simulations using the Morse potential functions for the copper substrate and the Tersoff potential function for the diamond abrasive. As the compressive pressure increased, the indented depth of the diamond abrasive increased and then, the speed of the diamond abrasive along the direction of the pad moving was decreased. Molecular simulation result such as the abrasive speed decreasing due to the pad pressure increasing gave important information for the chemical mechanical polishing including the mechanical removal rate with both the pad speed and the pad compressive pressure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.615-621
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• 2006

Increased application of optical disks requires more improved dynamic stability of rotating disks. In this study, a new concept of controlling the processing conditions of injection molded disks was developed to improve vibration characteristics. The critical speed, which shows stiffness and dynamic stability of disk, is affected by the residual stress distribution; this varies as functions of distance from the gate and processing condition. The critical speed of disk was calculated with the initial stress taken into consideration, which was determined from injection molding simulation. Choosing melt temperature, mold temperature, filling speed and packing pressure as design parameters, critical speed is maximized with the method of response surface. It is shown that the stability of injection molded disk has been improved for the new condition obtained as a result of the study proposed.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1738-1743
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• 2007

The newly established high speed railway station may function not only just as a traffic convergence but also as an energizing force with multiple roles in the context of municipal environment. As a result, the development of high speed railway station zone will be considered as great opportunities as well to enhance quality of life of the neighboring inhabitants, as to develop new footholds for the inner-municipal growth and mobilization. The main purpose of this article is to offer guidelines about the effects of development of the high speed railway station zone seen from multiple aspects of municipal lifes and functions. To attain this purpose, the definition of high speed railway station zone, its characteristics, and its roles will be handled with the case of advanced countries such as Japan and France. And some lessons will be proposed based on them.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.354-358
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• 1992

This paper describes a development of high speed fuzzy inference circuit for the industrialprocesses. The hardware fuzzy inference circuit is developed utilizing a hardware fuzzy inference circuit is developed utilizing a DSP and a multiplier and accumulator chip. To enhance the inference speed, the pipeline disign is adopted at the bottleneck and the general Max-Min inference method is slightly modified as Max-max method. As a results, the inference speed is evaluated to be 100 KFLIPS. Owing to this high speed feature, satisfactory application can be attained for complex high speed motion control as well as the control of multi-input multi-output nonlinear system. As an application, the developed fuzzy inference circuit is embedded to a PLC (Porgrammable Logic Controller) for industrial process control. For the fuzzy PLC system, to fascilitate the design of the fuzzy control knowledge such as membership functions, rules, etc., a MS-Windows based GUI (Graphical User Interface) software is developed.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.123-126
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• 2003

This paper proposes a speed-sensorless induction motor control system using the rotor flux error. The rotor flux observer uses the reduced- dimensional state estimator technique instead of directly measuring the rotor flux. The estimated rotor speed is obtained directly from the electrical frequency, the slip frequency, and the rotor speed compensation with the estimated q-axis rotor flux. To precisely estimate the rotor flux, the actual value of the stator resistance, whose actual variation is reflected, is derived. For fast calculation and improved performance of the proposed algorithm, all control functions are implemented in software using a digital signal processor (DSP) with its environmental circuits. Also, it is shown through experimental results that the proposed system gives good performance for the speed-sensorless induction motor control.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.49-58
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• 1997

In this paper, a transfer function was obtained for a PWM high speed solenoid valve controlled metal belt CVT system. The transfer function was defined as the ratio of speed ratio to PWM duty ratio and derived in time domain by linear regression analysis from the experimental results. The transfer function obtained showed different dynamic characteristics for the up and down shift. Also, LQG/LTR controller was designed for the CVT system using the transfer function. It is seen from the experimental results that LQG/LTR control showed good performance for the speed ratio tracking and disturbance rejection. The phase difference and relatively slow response are considered due to the inaccuracy os the transfer functions, which resulted from the inherent nonlinearities of the transmission characteristics of the metal belt CVT.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.746-756
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• 2001

An experimental study was conducted to investigated the effect of refrigerant flow control on the performance of a variable-speed heat pump operating in both cooling and heating mode. For this purpose, cooling and heating capacity, EER and refrigerant mass flow rate corresponding to an electronic valve as well as a capillary tube were measured as functions of compressor speed, length of capillary tube (or valve opening of the electronic valve), refrigerant charge, and outdoor temperature. From the comparison of experimental results, it was found that the performance variation due to the electronic valve opening became significant as the operating conditions(outdoor temperature and compressor speed) deviated from the standard condition at which heating capacity and EER were rated for the indicated capillary tube.

• Korean Journal of Computational Design and Engineering
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• v.11 no.6
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• pp.422-428
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• 2006

In this paper, an NC data optimization approach for enhancing 5-axis machining speed is presented. It is usual to use expensive commercial CAD/CAM programs for NC data of 5-axis machining, since it needs very large calculations for optimal tool positioning and orientation, tool path planning, and collision-free tool path generation. Since commercial CAD/CAM systems have similar functions and efficiency based on common algorithms of reliable theories, they do not have their own unique features for machining speed and efficiency. In other words, most commercial CAD/CAM systems consider only the characteristics of part geometry to be machined, which means that they generate almost the same NC data if the part to be machined is the same, even though different machines are used for the pin. A new approach is proposed for optimizing NC data of 5-axis machining, which is based on the characteristics of the machine to be operated. As a result, the speed of 5-axis machining can increase without losing machining accuracy and surface quality.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.2
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• pp.101-109
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• 2005

The newly developed speed sensorless control scheme is proposed to estimate both motor speed and rotor resistance simultaneously using variable rotor flux. The rotor flux is given as sinusoidal waveform with an amplitude and a frequency without affecting precise torque control. Especially the proposed method makes the simultaneous estimation of rotor resistance and speed with high precision even though at the low speed area including a few rpm. Moreover, on-line identification of rotor resistance can be performed simply without calculating troublesome trigonometric functions and complicated integral computation. Therefore, the proposed system can be accomplished by using very cheap microprocessors for several applications. The results of the numerical simulations and experiments demonstrate that this method is effective to estimate the speed and on-line identification of rotor resistance for sensorless induction motors.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1420-1422
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• 2000

The railway signaling system consists of micro-computerized vital devices on board and ground, which are connected to one another by track circuits, and interlocking equipment for route control. Therefore it is important to validate the required functions of developed system and interface between developed signaling systems. To verify the conditions and functions of signaling functions, the laboratory prototype test bench, which consists of personal computers LAN, will be developed. In this paper design of signaling system test-bench for high-speed signaling is described and developed software module are presented.