• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.571-575
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• 2005

A simple, but effective on-line method for estimating the mycelial cell mass concentration from agitation speed data, a most readily-available process variable, has been developed for DO-stat cultures of Agaricus blazei. The dynamic change of dissolved oxygen concentration (DOC) in the initial transient period and the change in yield were considered in the development of the estimation algorithm or estimator. Parameters in the estimation algorithm were calculated from the agitation speed data at 20% of DOC. The proposed estimator could accurately predict the cell mass concentration regardless of DOC levels in the tested range of $10{\sim}40%$, showing a good extrapolation capability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.806-809
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• 2000

The factors which can improve tool life in machining are consisted of tool geometries, tool materials, coating methods. cutting environments, cutting conditions and so on. Cutting speed in cutting conditions is one of the important factors which can directly influence on the tool life. This paper deals the machinability which is concerned about the cutting direction and the tilt angle of fret form surface in hot die steel(STD I I). The NC datum were analysrd and the effective tool diameters were calculated according to the change of tilt angle the program which can continue the cutting speed with the change of spindle revolution is developed.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.456-460
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• 2007

The original conventional railway was designed to be stand against 150km/h and it is still being operated at the present. However, if the speed of train is improved up to 200km/h in the near future in order to get competitiveness, we examined how the speed effect on the rail and we analyzed the effect of vibration, the stress and the displacement of the rail material by the change of the speed and the change of the property of matter through the hydrostatical and the dynamic analysis about the absence of the rail. As the result of the analysis by the above method, we got the prove that the best synthetic hardness of the rail is $75{\pm}10KN/mm$. Therefore, it is proved that rail pad has to be improved.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.780-786
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• 2001

For the compressor speed control of a multi-type air conditioning system, a fuzzy control algorithm was developed. The sum of zone temperature errors and its derivative were used as input variables, and the compressor speed was selected as the output variable. To test the effectiveness of the control algorithm, one outdoor environmental chamber and four indoor environmental chambers were used. In the chambers the zone temperature step change test and the indoor unit change over test were performed. Test results showed that, for the control of compressor speed, the fuzzy control algorithm was more effective than the conventional proportional control algorithm for the energy conservation.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1221-1226
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• 2008

Present, the cooling method of using a phase-change heat transfer such as immersed type, heat pipe etc is applied in cooling of high-capacity power semiconductors of the main power system for the high speed train with the concentrated traction. In order to apply these phase-change cooling system to the high speed EMU to be developed, needed are technological researches of consideration of installing space, air passage, light weight material and miniaturization. Although this research establishes design specifications through theoretical analysis and computational analysis from the basic design process of the cooling system of the propulsion system for the high-speed EMU, when details design is completed, present improvement subject and optimum design before manufacturing the prototype of the cooling system on the basis of analysis results. And then, carried out will be the performance tests through prototype manufacture and reliability estimation by components of cooling system.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.42-54
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• 2009

The wind load equation for the design of electric power facilities such as electrical pole in railroad is based on the maximum wind velocity without considering regional difference in wind velocities. Also, the use of a different equation to highspeed railroad and the possibility of higher wind speed due to climate change claims a new design equation. In this paper, a wind load equation based on wind speed measurement data to date, which is applicable to both conventional and highspeed railroad is proposed. The proposed equation considers the regional differences in wind speed for economic and effective design, and the possibility of higher wind speed due to climate change.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.4
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• pp.441-447
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• 2007

The speed and torque control performance of the DC motor used in the industrial field is affected by the change of parameters. In particular the change of armature resistance can be greatly originated from various load conditions. Accordingly a large number of studies to estimate those problems in the servo motor control field have already been under way. In this paper, the armature resistance on the DC motor under several load and speed conditions is estimated by the Artificial Neural Network(ANN), and the validity is proven by the speed estimation of sensorless speed control system.

• Korean Journal of Computational Design and Engineering
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• v.22 no.2
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• pp.190-201
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• 2017

This paper proposes how to solve a problem of FDM 3D printer's irregular output when changing volume of extrusion, adjusting movement speed of the printer's head and a way to fill new inner part. Existing slicers adjust directly to change the rotation speed of the stepper. In this method, the change of the extrusion area is delayed due to the gap between the stepper and the nozzle, so that precise control is difficult. We control the extrusion area adjusting the moving speed of the print head and making constantly the rotation speed of the stepper. Thus, the output time can be shortened by generating an efficient path having a short travel distance. For evaluation, we applied our method to lithophanes with detailed variation. Comparing existing methods, our method reduced output time at least 30%.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.8
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• pp.168-175
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• 1995

A robust speed control algorithm under disturbances and reference change is developed using the self tuning control method in order to control induction motors. The method incorporates the concepts of the well known internal model principle and the annihilator polynomial. The effectiveness of the method is evaluated through the speed control experimental results of an induction motor for refernce change and arbitrary distrbance.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.220-224
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• 2002

As the train run through the tunnels, especially at high speed, pressure shock developed by the running train gives the influence on the pressure fluctuation inside the tunnel and consequently, inside the car. This pressure changes and pressure gradient is closely related with the tunnel section, train speed, air tightness of the train, length of the tunnel, etc. This study includes the analysis of the pressure behavior at the varied train speed and tunnel length. The results show that train speed affects the pressure gradient inside the car almost linearly, and that there exist the critical tunnel lengths that gives the maximum value of pressure change and pressure gradient, respectively.