• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.28-33
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• 1996

This paper presents a position control of ultra-precision machine tool post using piezoelectric material. A stack-type piezoelectric actuator is employed in a hinge-type tool holder. An assumed linear transfer function of the practical nonlinear plant is established through the comparison of transfer functions and step responses in the experiments and the simulations. Several types of feedforward/feedback controllers are designed via computer simulations using the assumed linear transfer function, The position tracking control experiments are undertaken to show the control efficiency of each controller.

• Asian Journal of Turfgrass Science
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• v.11 no.3
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• pp.161-166
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• 1997

This study was performed to develope the method of wildgrass to process as hydroseeding material which is a most popular revegetation method for Slope areas through the control of soil eroison and stability by seeding grasses. The wildgrass material for the processing were harvested at Suwon, Kyungki-do and Wonju, Kangwon-do in 1994. The investigations were established in laboratory for pot and field experiment with seven treatments by harvesting date and place in 1995. Results indicated that wildgrass harvested field in open space or road side was able to be used as hydroseeding material by proper processing. It was possible to substitute wildgrass seed to conrrnercial turfgrass seed, and plant tissue to mulching fiber by drying and crushing process. Germination of wildgrass seed was relatively slower than control (20g /$m^2$ turfgrass seed) in early stage of 20 days, but surface revegetation rate was higher in 50 days at wildgrass plot than control applied by normal hydroseeding method. Mixture of 5g /$m^2$ of cool season turfgrass seed to wildgrass material increased the rate of early stage of germination and surface revegetation. The application of wildgrass as hydroseeding material showed more naturalistic scenery than rutine hydroseeding with imported cool season turfgrass seed. Key words: Rydroseeding, Turfgrass, Wildgrass, Revegetation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.5
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• pp.533-540
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• 2008

In this study, a new slab system where a part of precast slab is connected each other by viscoelastic material is proposed and numerical analysis is performed to evaluate the effect of the connection between the material and PC slab on the vibration and noise control. Substructuring is introduced to develop the equation of motion for the slab system. In addition, the optimal properties of viscoelastic material are investigated. For the performance evaluation of the new slab system, the sound power and acceleration responses of the slab are compared with those of two way slab and one way slab, respectively. Numerical analysis results show that the sound power of the new slab system can be reduced by viscoelastic material significantly.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.254-258
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• 2004

Actual trends in automotive industry lead to an increase use of lightweight structures imposing the need fur high strength aluminum alloys with complex shape. In the electromagnetic stirring process, it has many merits which are the exact control ability about material processing and a good point of the protection of environment comparison with the mechanical stirring. The interface of cells consisting of primary particle formed by the electromagnetic stirring due to particle regrowth during cooling the alloy. By electromagnetic stirring process, the microstructure of material has a good point, also it can control the material processing exactly.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.142-149
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• 2002

In this paper, the metal forming process is caused of rise of the unit cost of production in increase of the lead-time and cost because of manufacturing final product through a few the number of processes. Flow control complex forming is proposed to put into formulation in order to apply cold forging from conventional approximate similarity theory, and the forming loads of the real material(AISI 1008) can be calculated by put at the new similarity formula the load by plasticine model material experiment through hub clutch. In order to reduce lead-time and cost the technology is used to manufacture with lower die of this product. By the application synthetic resin as the raw material, it is have the merit such short lead-time, low cost, good surface finish etc., as compared with the machine work.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.394-397
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• 2007

This study aims to examine its problems, control and handling by analyzing Barcode System, one of the Material Handling which are currently often used in medical Industry, and improve the present unnecessary orders and handling to improve material control and handling related to medical supplies by applying these days appearing RFID(Radio Frequency IDentification) System to material handling system. By this, it is expected that reduction of unnecessary inventory and exact information acquisition of goods will be possible. And by this, this study also aims to build and use closer cooperation system between hospitals and material system reducing time needed for material handling by controlling material flow effectively by taking advantage of them effectively.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.1017-1021
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• 2005

There is a need for effective tracking and control of material loading and delivery time especially during the finishing-work phases to eliminate the need for lay-down space on the site. Hence, it is essential to monitor the relevant information regarding material procurement in construction sites, and it is also the key factor for successful site control and the adoption of the Just-in-Time concept for high-rise building construction. The purpose of this study is to test RFID's readability in order to develop a finishing material monitoring system through the application of RFID technology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.103-105
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• 2002

Instantaneous following PWM control technique is pulsed nonlinear dynamic control method. This new control technique using analog integrator is proposed to control the duty ratio D of Cuk converter. In this control method, the duty ratio of a switch is exactly equal to or proportional to the control reference in the steady state or in a transient. Proposed control method compensates power source perturbation in one switching cycle, and the average value of the dynamic reference in one switching cycle. There is no steady state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with Cuk converter have demonstrated the robustness of the control method and verified theoretical prediction. The control method is very general and applicable to all type PWM.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.3
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• pp.32-37
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• 2005

Several types of smart materials and control scheme are available to adjust the structure actively in various external disturbances. A control scheme was introduced for a specific material. But the effectiveness of the control scheme has some limitation according to the choice of the smart materials and the response of the structure. The ER(Electrorheological) fluid is adequate for a large control force, and the PZT(lead zirconate titanate) patches are suitable for small but arbitrary control force at any point of the structure. It can be used for active control of structure by changing the dynamic characteristics of the structure. But it has some difficulty in suppressing the excited vibration in broad band. To compensate this resonance of the controlled structure, a hybrid controller was constructed using PPF(Positive position feedback) control with PZT and ER fluid control.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.138-142
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• 2003

In this study, to show well favorable characteristics of warm forged material, we compared and analyzed microstructure and mechanical properties of general hot-forged material which finished heat treatment with warm-forged material which was produced by control cooling condition. Along with this, we suggested better direction of control cooling condition to be able to remove heat treatment process while satisfying mechanical properties.