• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.375-381
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• 2004

Recently, the evolution in production techniques (e.g. high-speed milling) and the complex shapes involved in modem production design has been increasingly popular. The key to the achievement is a drastic improvement of the dynamic behavior of the machine tool axes used in production machinery. The more complex these tool paths the higher the speed and acceleration requirements. But it is very difficult to reach the target for high speed machine tool because of the limitations of servo system and motion control system. However the direct drive design of machine tool axes, which is based on linear motors and which recently appeared on the market, is a viable candidate to meet the ever increasing demands, because of these advantages such as no backlash, less friction, more mechanical simplicity and very higher acceleration and velocity comparing to the traditional system. This paper focused on the performance tests of the high speed horizontal machine tool based on linear motor. Especially, dynamic characteristics were investigated through circular test and circular form machining test is carried out considering many important parameter. Therefore these several experiments is used to be evaluated the model for prediction of circular motion error and circular machined error.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.642-648
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• 2019

This paper presents a fast back-type transfer device for snack food processing that uses the inertia of transferred material. A conventional conveying system is a drive system that uses a belt conveyor and mechanical crank, which generate noise and vibration and cause environmental pollution. Vibration and noise are reduced in the proposed fast back feeding device by using a counterweight. The crank drive unit was replaced with a linear servomotor, and an equilibrium device was designed to balance the force due to acceleration. This makes it is possible to adjust the forward and backward speed and acceleration through PLC control. A vibration damper device offsets the vibration force of the periodic shock form. The main cause of the vibration was identified through vibration analysis, and reduction measures were established. We verified the effectiveness of the vibration by making a prototype and performing about 10 vibration tests. Because no mechanical transducer is needed, energy loss, noise, and vibration do not occur, and the operating speed is not limited.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.158-161
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• 2003

Recently, the evolution in production techniques (e.g. high-speed milling), the complex shapes involved in modem production design, and the ever increasing pressure for higher productivity demand a drastic improvement of the dynamic behavior of the machine tool axes used in production machinery. And also machine tools of multi functional and minimized parts are increasingly required as demand of higher accurate in some fields such as electronic and optical components etc. The accuracy and the productivity of machined parts are natural to depend on the linear system of machine tools. The complex workpiece surfaces encountered in present-day products and generated by CAD systems are to be transformed into tool paths for machine tools. The more complex these tool paths and the higher the speed requirements, the higher the acceleration requirements are needed to the machine tool axes and the motion control system, and the more difficult it is to meet the requirements. The traditional indirect drive design for high speed machine tools, which consists of a rotary motor with a ball-screw transmission to the slide, is limited in speed, acceleration, and accuracy. The direct drive design of machine tool axes. which is based on linear motors and which recently appeared on the market. is a viable candidate to meet the ever increasing demands, because of these advantages such as no backlash, less friction, no mechanical limitations on acceleration and velocity and mechanical simplicity. Therefore performance tests were carried out to machine tool axes based on linear motor. Especially, dynamic characteristics were investigated through circular test.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.951-959
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• 2016

The aim of this paper is to investigate the improvement of surface characteristics of Stellite21 deposited layer by powder feeding type of direct energy deposition (DED) process using a plasma electron beam. Re-melting experiments of the deposited specimen is performed using a three-dimensional finishing system with a plasma electron beam. The acceleration voltage and the travel speed of the electron beam are chosen as process parameters. The effects of the process parameters on the surface roughness and the hardness of the re-melted region are examined. The formation of the re-melted region is observed using an optical microscope. Results of these experiments revealed that the re-melting process using a plasma electron beam can greatly improve the surface qualities of the Stellite21 deposited layer by the DED process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.1
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• pp.31-39
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• 2004

This paper presents design solutions for cam type transfer unit in which feeding, lifting, and clamping motions are generated by cams. In order to achieve faster transfer motion, each designed cam must satisfy the given specifications such as velocity, acceleration, jerk, pressure angle, cam thickness, and torque. To reduce absolute torque magnitude and torque variation, a conjugate cam and a torque reduction cam are used respectively. The conjugate cam eliminates the redundant pre-load by using complementary cam to avoid jumping between a cam and a follower. The torque reduction cam reduces the torque variation by applying opposite torque to a cam shaft. The experimental result shows the reductions of the absolute torque value and torque variation. The improvement of working speed and life span of cam type transfer unit can be expected.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.171-176
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• 2003

A Test Facility was established to carry out the integrated propulsion performance tests(IPPT). To perform IPPT's with maximum safety, an emergency blockage system was investigated. An emergency blockage system using combustion chamber pressure and acceleration signals was set up to monitor ignition delay and fail, flame out, propellant feeding status, unstable combustion and excessive structural vibration. With such system, the maximum safety could be secured by rapid judgement and follow-up measures, which made IPPT's be safely completed.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.358-363
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• 1987

It is widely noted that pressure feedback systems have been devised to damp the fluid resonance effectively in precision speed control-for large inertia system. A compensation technique preserving the natural output disturbance discrimination characteristics at lower frequencies is proposed The load pressure across positive displacement acceleration. The technique involves feeding back load differential pressure, sensed by pressure transducers, though a simple analog compensatory circuit (high pass filter). The effectiveness of the damping is determined by the filter time donstant and loop gain. Nonlinear total hydraulic simulation results verify the possibility of linear model predictions of extending the closed loop bandwidth beyond the uncompensated frequency.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.8
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• pp.351-357
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• 2005

This paper presents vibration minimization of a PMLSM driven feed-slide by using optimized smooth velocity curve with finite jerk. First of all, the PMLSM was designed and made to reduce detent force. Next, a PMLSM driven feed-slide system was mathematically modeled as a 4-degree-of-freedom lumped parameter model. The key idea of our vibration minimization method is to find out the most appropriate smooth velocity(feedrate) curve with finite jerk. The validity of our proposed method has been verified by comparing computer simulation results of the feed-slide model with experimental ones.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.333-334
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• 2016

This paper proposes a new cascoded configuration for hybrid energy storage system (HESS) which consists of batteries and supercapacitor (SC) for Electric Vehicle applications. In this configuration,a resonant LLC converter is interfacedin series with a battery module and it converts a part of the energy from the batteries and transfer it to the dc-link bus. The LLC converter is controlled by a phase-shift angle between the primary and secondary switches to maintain a constant dc-link voltage and obtain soft-switching conditions for all the primary switches. By placing the SC moduleina cascoded concept, the rated voltage of SC can be reduced significantly compared with the conventional topologies. It helps save the cost and reduce the number of SC cells. The proposed configuration can operate with four different modes: feeding load, acceleration, regenerative braking andSC charging. A scaled-down prototype converter (2 kW, 600V output) is designed and tested to verify the advantages of the proposed topology. The maximum efficiency obtained with the proposed topology is 99%.

• Journal of Aquaculture
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• v.16 no.1
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• pp.51-58
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• 2003

The first Indian transgenic fish was generated in 1991 using borrowed constructs from foreign sources. To construct transformation vectors for the indigenous fishes, growth hormone genes of rohu (r-CH), Labeo rohita and catfish, Heteropneustes fossilis were isolated, cloned and sequenced; their fidelity was confirmed in prokaryotic and eukaryotic systems. A vector was constructed with grass carp b-actin promoter driving the expression of r-GH. Rohu eggs are large. fragile and swell 2~3 times. when fertilized. Hence they were amenable only for electroporated sperm-mediated gene transfer. Accordingly, the sperm electroporation technique was standardized to ensure 25% hatchling survival and 37% Presumptive transgenics without suffering any deformity. Southern analysis confirmed genomic integration in 15% of the tested individuals (Ti) belonging to family lines 2 and 3: another 25% of the Juveniles (Te) were also proved transgenic but with the transgene persisting extrachromosomally for longer than 1 to 2 years. perhaps due to the presence of replicon in the vector. Transgenics belonging to different family lines grew 6~8 times faster than the respective controls. Difference in growth trends of Ti and Te within a family line was not significant. In the Ti family 3 remarkable growth acceleration was sustained for a period longer than 36 weeks but in those of family 2, it gradually decreased. All transgenic fishes including the rohu converted the food at a significantly higher efficiency. Barring the transgenic mudloach, all the other transgenic fishes consumed food at significantly reduced rate.