• Journal of Advanced Marine Engineering and Technology
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• v.22 no.2
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• pp.190-199
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• 1998

a new measuring method is suggested to determine the time constant of a thermocouple wire to be applied for the measurement of the true fluid temperatures in varying flow states. Based on the techniques of internal heating which are commonly used to measure mean time constants we extend the existing method to measure instantaneous time constants continuously. A method of measurement and analysis is presented and verified experimentally.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.163-171
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• 1999

The abnormal grain coarsening in wire rolling induces detrimental defects, such as jagged size tolorance, severe bending after heat treatments and drawing troubles, in the following secondary processes. Neishi et al observed that there is a band type region where grain coarsenting occurs in the plastic strain vs. deformation temperature plot. Based on the finding, we have investigate whether grain sizes and ferrite volume fractions are correlation to deformation strain with three kinds of wire rod diameters as for the different average deformation conditions. The samples were chosen from the No.2 Wire Rod Mill of POSCO where 3-roll type of finishing mill stand are used. It was found in the present work that the grain size and ferrite volume fraction of the rolled and cooled microstructure were changed with rolling reduction and rolling temperature. Abnormally grown grains at various observed points were also found. To have homogeneously fine grains of microstructure from the No. 2 Wire Rod Mill, it will be easier to control finish rolling temperature at around 750$^{\circ}C$ rather than to find another rolling schedule.

• Solar Energy
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• v.19 no.3
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• pp.43-51
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• 1999

Axisymmetric circular water jet impinges against rectangular heated surface with uniform hear flux and wire-mesh screens are set up in the nozzle-to-heater space to augment heat transfer. In the free jet region to be used them, pressure drop and intensive turbulence flow was brought up. When water jet system is not used wire-mesh screens, maximum heat transfer appears in the stagnation point and the secondary maximum appears X/D=4 but it disappears when they are is used. In the low velocity(Vo<6.0m/s), coarse mesh-screen enhanced heat transfer but fine mesh-screens inpeded heat transfer. In the high velocity(Vo>6m/s), all of them enhanced heat transfer. Average Nusselt number of experimental system to be used wire-mesh screens was promoted $4{\sim}6$times than that of simple water jet system. The stagnation heat transfer of experimental system to be used wire-mesh screens was augmented 6times that of simple water jet system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.175-180
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• 2005

In this study, we have developed a novel wire straightener which uses the direct heating method (DHM) fer straightening the micro wire. Also, we have developed a shearing device for cutting the micro wire. In order to avoid the surface oxidization, we supplied the inert gas(Ar) during the heating process and examined the effect of gas flow rate. The effects of the tension and the current applied to the tungsten micro wires were also thoroughly studied. From various experiments and analyses, we could obtain fine straightness $(\approx1\;{\mu}m/1000\;{\mu}m)$ and roundness $(<{\pm}2{\mu}m\;/100{\mu}m)$ when the tension is $500\~~600gf$ and the current is about 1.5A. for burrfree cutting, counter-punch method which two cutters moving contrary was used. The cutting blade has various U-groove angle where upper $10^{\circ}$, $mid:25^{\circ}$, lower $0^{\circ}$. After the shearing process, we confirmed the shearing section.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.419-427
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• 1999

TiNi shape memory alloy was shape memory heat-treated and investigated its mechanical properties with the variation of prestrain. Also 6061 Al matrix composites with TiNi shape memory alloy fiber as reinforcement have been fabricated by Permanent Mold Casting to investigate the microstructures and interface properties. Yield stress of TiNi wire was the most high in the case of before heat-treatment and then decreased as increasing heat-treatment time. In each heat-treatment condition, the yield stress of TiNi wire was not changed with increasing the amount of prestrain. The interface bonding of TiNi/6061Al composite was fine. There was a 2$\mu\textrm{m}$ thickness of diffusion reaction layer at the interface. We could find out that this diffusion reaction layer was made by the mutual diffusion. The diffusion rate from Al base to TiNi wire was faster than that of reverse diffusion and the amount of the diffusion was also a little more than that of reverse.

• IE interfaces
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• v.10 no.3
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• pp.125-132
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• 1997

We proposed a 2-step neural network approach for estimating machining parameters of electric discharge wire cut. The first step net, which is described as a backward neuro-estimation, is designed for estimating coarse cutting parameters while the second phase net, as a polishing forward neuro-estimation, is utilized for determining fine parameters. Sequential estimation procedure, based on backward and forward net, is performed using the net's approximation capability which is M to 1 and 1 to M mapping property. Experimental results an given to evaluate the accuracy of the proposed 2-step neuro-estimation.

• ETRI Journal
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• v.16 no.2
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• pp.1-13
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• 1994

We have identified two new features related to the coherent transport in the mesoscopic loop structure of aluminum wire, including the autocorrelation of the conductance fluctuations beyond $B_c$ and fine structure in the low-field magnetoresistance curve in the superconducting transition regime, which, to the best of our knowledge, have not been reported in the literature. Since the electrons in Al have a phase coherence length larger than $1\;{\mu}m$ at or below T = 3K, which is comparable to the dimensions of the structure, the wave nature of the electronic transport has been clearly observed: the universal conductance fluctuations, the Aharonov-Bohm oscillations, and the Altshuler-Aronov-Spivak oscillations. Due to the transition of Al to a superconducting state at T = 1.3 K, the coherent phenomena of Cooper pairs, i.e., the Little-Parks oscillations, have also been observed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1573-1576
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• 2003

The quality of bundles is closely related with the apparent thickness. Especially the variation of apparent thickness of bundle determines the qualify of the plane structure made or the bundle such as surface evenness, pore size, and the shape of air-gap, etc.,. This study is dealing with the development of a new measuring system of the thickness of bundle or cross-section by determining the size of the shadow of the object covered by a laser slit beam. Also the measured signal is characterized in terms of the correlogram, the irregularity in wavelength. The correlogram for the irregularity of several sample types could be represented by a sinusoidal function with exponentially decaying amplitude. Moreover, influence of the measuring speed on the signal and the characteristic differences according to the different types of bundle are investigated.

• Journal of KSNVE
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• v.8 no.2
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• pp.346-352
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• 1998

This paper presents actuating characteristics of an asymmetric high-speed optical pick-up fine actuator that can be installed in a small area such as a notebook personal computer. In the asymmetric actuator four points (mass center, actuation center, supporting point of wire suspension on a bobbin, and optical axis) are not coincident so that the proposed actuator suspension reveals undesirable suspension resonance in the pitch and yaw direction. Lumped parameter dynamic model in each direction is used to investigate the driving characteristics with respect to relative location of the four points. Some of desired design directions toward reducing resonance peaks are suggested by using sensitivity information. In order to avoid undesirable resonance, at least supporting point on the obbin must be located in the middle of the mass and actuation center of the asymmetric pick-up actuator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.354-354
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• 2009

We have developed the prototypes of superconducting magnetic separation system with high temperature superconductor wire. This separation filter system consist of magnetized matrix SUS430 wire and acrylic frame. This study introduced rolled steel process coolant wastewater applied superconductor HGMS(High Gradient Magnetic Separation). HGMS treatment have acted high efficient method for various wastewater. We have surveyed superconducting magnetic separation technology and reviewed the status of related industries using applied superconductivity. In our basic preliminary experiment using HGMS, it was made clear that the fine para-magnetic particles in the wastewater obtained from rolling process of steel can be separated with high efficiency. We investigated the ability of magnetic flock formation, which used inorganic materials and polymer coagulants. We had a purpose to remove SS of coolant at steel factory. Maximum coagulation remove rate of SS 98%. Removing ratio of $Fe_3O_4$ fine particles in wastewater showed over than 99% in the wastewater containing magnetic fines after four times of repetition of separation.