• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.4
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• pp.102-106
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• 2002

Development of high speed feed drive system has been a major issue for the past few decades in machine tool industries. The reduction of the tool change time as well as rapid travel time can enhance the productivity. However, the high speed feed drive system generates more heat in nature, which leads thermal expansion that has adverse effects on the accuracy of machined parts. The detail of the model proposed is described in the paper together with the experimental methodologies using a proposed compact measurement system to examine the validity of the proposed approach. The results showed the machining accuracy could be maintained to better than $\pm$ 5$\mu\textrm{m}$ while using this sensor.

• Journal of KSNVE
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• v.6 no.5
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• pp.555-565
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• 1996

This paper is concerned with the theoretical and experimental study on the force control of a miniature robotic finger that grasps an object at three other positions with the fingertip. The artificial finger is a uniform flexible cantilever beam equipped with a distributed set of compact grasping force sensors. Control action is applied by a piezoceramic bimorph strip placed at the base of the finger. The mathematical model of the assembled electro- mechanical system is developed. The distributed sensors are described by a set of concentrated mass-spring system. The formulated equations of motion are then applied to a control problem in which the finger is commanded to grasp an object. The H$_{\infty}$-controller is introduced to drive the finger. The usefulness of the proposed control technique is verified by simulation and experiment..

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.336-339
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• 2006

With the steady depletion off fossil fuel reserves, hydrogen based energy sources become increasingly attractive. Therefore hydrogen production or separation technologies, such as Bas separation membrane based on adsorption technology, have received enormous attention in the industrial and academic fields. In this study, the transport mechanisms of the MTES (methyltriethoxysilane) templating silica/a-alumina composite membrane were evaluated by using unary, binary and quaternary hydrogen gas mixtures permeation experiments at unsteady- and steady-states. Since the permeation flux in the MTES membrane, through the experimental and theoretical study, was affected by molecular sieving effects as well as surface diffusion properties, the kinetic and equilibrium separation should be considered simultaneously in the membrane according to molecular properties. In order to depict the transient multi-component permeation on the templating silica membrane, the GMS (generalized Maxwell-Stefan) and DGM (dust Bas model) were adapted to unsteady-state material balance

• Journal of Powder Materials
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• v.4 no.2
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• pp.90-99
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• 1997

Densification behavior and grain growth of tool steel powder compacts during pressureless sintering, sinter forging, and hot isostatic pressing were investigated. Experimental data were compared with results of finite element calculations by using the constitutive model of Abouaf and co-workers and that of McMeeking and co-workers. Densification and deformation of tool steel powder compacts were studied by implementing power-law creep, diffusional creep, and grain growth into the finite element analysis. The shape change of a powder compact in the container during hot isostatic pressing was also studied. The theoretical models did not agree well with experimental data in sinter forging, however, agreed well with experimental data in hot isostatic pressing.

• Journal of the Korean Society of Combustion
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• v.23 no.1
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• pp.21-27
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• 2018

The effect of swirl flow structures on combustion dynamics of two interacting, lean-premixed flames was experimentally investigated, with a particular emphasis on swirl numbers and swirl rotational directions. Our results show that the amplitude of limit cycle oscillations is very sensitive to the combination of swirl numbers and rotational directions, while the instability frequency remains nearly unchanged. The counter-rotating cases show significantly lower pressure perturbations, and this behavior appears to be related to the formation of compact interacting zone with higher heat release rate, indicating the presence of increased flame surface wrinkling caused by intense turbulence.

• The Journal of Korea Robotics Society
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• v.8 no.3
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• pp.164-172
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• 2013

This paper presents a new concept of a 1-DOF elbow exoskeleton driven by a twisted strings-based actuator. A novel joint actuation mechanism is proposed and its kinematic model is presented along with its experimental evaluation, and guidelines on how to choose the strings suitable for such an exoskeleton are given. We also proposed and experimentally verified a human intention detection method which takes advantage of intrinsic compliance of the mechanism. The study showed that the developed twisted strings-driven elbow exoskeleton is light, compact and have a high payload-to-weight ratio, which suggests that the device can be effectively used in a variety of haptics, teleoperation, and rehabilitation applications.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.49-51
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• 2008

The wide-band spiral inductor to be monolithically integrated on the AlN substrate as a choking inductor for a compact 10 Gb/s optical transmitter applications is investigated. In order to reduce the parasitic capacitance limiting the choking bandwidth, the AlN substrate is partially etched away, which is analyzed by using an equivalent circuit model. The measured $S_{21}$ transmission response of the fabricated inductor is suppressed as low as -10 dB in the frequency range of 5 to 16 GHz.

• Journal of electromagnetic engineering and science
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• v.15 no.3
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• pp.129-133
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• 2015

This paper presents the dosimetry of a resonance-based wireless power transfer (RBWPT) system for electric vehicles applications. The compact RBWPT system is designed to transfer power at 150-mm distance. The electric and magnetic fields generated by the RBWPT system and the specific absorption rate in the human body model, which stands around the system, are calculated. These analyses are conducted in two cases: the alignment and the misalignment between the transmitter and the receiver. The matching loops are adjusted to maximize the power transfer efficiency of the RBWPT system for the misalignment condition. When the two cases were compared for the best power transfer efficiency, the specific absorption rates (SAR) in the misalignment case were larger than those in the alignment case. The dosimetric results are discussed in relation to the international safety guidelines.

• International Journal of Fluid Machinery and Systems
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• v.2 no.3
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• pp.248-253
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• 2009

This paper presents a numerical study for unsteady flows in a high-pressure steam turbine with a partial admission stage. Compressible Navier-Stokes equations are solved by the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is also solved for evaluating the eddy-viscosity. The unsteady two-dimensional flows through whole nozzle-rotor cascade channels considering a partial admission are numerically investigated. 108 nozzle passages with two blockages and 60 rotor passages are simultaneously calculated. The influence of the flange in the nozzle box to the lift of rotors is predicted. Also the efficiency of the partial admission stage changing the number of blockages and the number of nozzles is parametrically predicted.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.4
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• pp.357-363
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• 2004

Earlier models of card vending machines have generally motion drives with high cost and large size. However, current trend in card vending machines requires low-cost, compact-sized and readily installable motion drives. This paper shows the operational principle of the motion drive of a card vending machine and then presents the performance test results of the motion drive with improved mechanisms proposed in the paper. The results show that the proposed mechanism is valid and improves the card dispensing performance. The proposed model in the paper is accepted and introduced in the actual production line.