• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.103-108
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• 1999

A synthesized model of pultrusion process considering thermally induced deformatiion was established. The model was composed of liquid resin flow model thermo-chemical analysis and linear elastic analysis. in order to verify the above-mentioned models several experiments were performed. A laboratory scale pultrusion line was established and glass/polyester composites were fabricated. the experimental results were compared with the calculated ones. The model successfully could estimate degree of cure pulling force and amount of process-induced deformation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.48-53
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• 2004

Injection molded plastic parts have many surface defcts: Warpage, wedline, flowmark, zetting, scratching, shading and so on. In the desktop mnitor's case, Weld line have been one of the main surface defects. Nowadays in the pursuit of light weight of parts, one of the big problems of LCD Monitor thinks Warpage and surface shrinkage. In this paper, we introduce some instances for prevevting these defestcs in the side of mould drawing, parts drawing and processing condition. Based on these, we tried to find out the optimum processing conditions through repeatedly tried injection moulding after reflecting these instances.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.3
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• pp.305-310
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• 2001

Hydraulic power shifting systems of hydraulic travel motor may be far safer than mechanical power transmission systems. Thus, hydraulic power shifting systems are widely used for speed control on the hydraulic equipments. In the case of liquid shifting lines, the rapid change of area, such as valve closing, can result in a large pressure transient. It is necessary to assure proper control method in order to obtain the smallest shift shock. This study conducts the shock characteristics of hydraulic power shifting system of the hydraulic travel motor. Experimental results show that shock pressure depends on the operating pressure, flow rate and pipe line area. The shock characteristics can be applied for reducing shocks.

• Korean Journal of Optics and Photonics
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• v.11 no.2
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• pp.91-96
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• 2000

We propose a novel in-line fiber optic circular polarizing mirror utilizing cholesteric lIquid crystal (CLC) polymer [11m for the fiber laser applications. Ions matrix representation of this device has been derived and venfied experimentally. In a Fabry-Perot cavity configuration, a CLC fiber optic rmrror has been used to achieve longitudinal mode suppression as well as to obtain passively mode~locked laser operations with 630 fs laser pulses via nonlinear polarization evoluhon.oluhon.

• Progress in Superconductivity
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• v.9 no.2
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• pp.188-192
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• 2008

We investigated the size effect on quench development in $Au/YBa_2Cu_3O_7$ (YBCO) thin film meander lines on sapphire substrates. The meander lines were fabricated by patterning YBCO films coated with gold layers. The lines were subjected to simulated AC fault current, and immersed in liquid nitrogen during the experiment. After the initial rapid rise, the resistance increased moderately and then slowly. In 4 inch-diameter meander lines, the period during which the resistance increased moderately was considerably longer than in 2 inch-diameter line. Moderate increase of resistance was originated from quench propagation. The film temperature was about 180 K at the point when the propagation was completed. The rate of resistance increase after the quench completion was not affected by the film size.

• Journal of Engineering Education Research
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• v.19 no.2
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• pp.3-7
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• 2016

A flow control system was designed and fabricated to control the flow rate of liquid through the pipe. This control system was composed of hardwares and software, hardwares as controller, gate valve, orifice meter and data aquisition board and software as National instruments Labview program. Control of flow rate was executed by adjusting the pneumatic valve located at the center of pipe line based on the control signal generated by LabView PID control algorithm, which converts analog signal measured by pressure difference of orifice to digital signal to adjust pneumatic valve. For the controller setup Ziegler-Nichols tuning technique was applied and control performances were investigated for not only the disturbance but also the set point changes. Developed system showed good control performances in flow control enough to use as teaching tool of feedback control theory and practice in university, and also as industrial application.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.35-44
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• 2004

In this study, one dimensional aerodynamic and structural study of a partial admission turbo pump turbine was performed. A turbine consists of a nozzle, rotor, outlet guide vanes. The aerodynamic characteristics of each component was derived from the governing equation and validated from the CFD calculations. One-dimensional basic design such as velocity triangles was conducted from the mean line analysis and modified from the 2-D and 3-D CFD analysis. The blade profile was determined by the CFD optimization. The thermal stress analysis and structural analysis are needed to be studied in the next design stage.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.167-168
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• 2000

We propose a signaling circuit that can reduce power consumption and Electromagnetic Interference (EMI) in a Liquid Crystal Display (LCD) controller-to-source driver interface. The proposed signaling circuit consists of a coder/decoder that can minimize temporal bit transitions in a transmission line and a current-mode driver that can convert voltage swing into a very small amount of current. We have simulated the proposed signaling circuit using the HSPICE and the proposed signaling circuit has been designed in a 0.25 ${\mu}m$ CMOS technology.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.377-379
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• 2001

Contamination flashover is responsible for insulator electrical failures. Particularly, in Korea, with its perennially dry spring, the first spring rain often cause serious line outages by forming a conductive liquid film on the insulator surface. Rainwater and fog are not normally conductive but unfortunately atmospheric dust deposited on the insulator surface contains soluble salts which may lead to bad condition of insulation by combining watery and salts. Transmission design engineers have used a contamination map drawn on the traditional paper map. But it is not convenient because it does not include the information of Geographic Information accurately. This paper explains the newly developed salt contamination map program using Geographic Information System, which provide accurate geographic information. The program is designed to use four parts of datum, salt contamination levels, 345kV & 154 kV transmission lines, power plants & substations and background map. The digital background map is composed of raster files, the others are done by vector map.

• Journal of ILASS-Korea
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• v.12 no.4
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• pp.191-197
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• 2007

This study presents in-line digital particle holography and its application to spray droplets to measure the characteristics of spray droplets. Several important parameters at the time of hologram recording such as the object distance and the region of laser beam used were verified. The correlation coefficient method with important parameters such as the reconstruction interval and the correlation interval was used for determination of the focal planes of particles. The optimal values of all these parameters are obtained by either numerical simulation of holograms or experiments. Using these optimal parameters, double pulse digital spray holograms in a short time interval were recorded with the synchronization system for the time control. The spatial positions of droplets that are used for the evaluation of the three dimensional droplet velocities can be easily located, which proves the feasibility of the digital holographic technology for measurements of several important features of spray droplets.