• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.57-64
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• 2008

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass material, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of an electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.1
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• pp.21-25
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• 1999

The TiN, thin films were prepared on glass substrate by RF(radio-frequency) magnetron sputtering apparatus from a Ti target in a gaseous mixture of argon and nitrogen. In deposition, a RF power supply was used as a power source with a constant power of 240W, and the substrate was heated to $200^{\circ}C$. The films were obtained at nitogen flow rates in the range 3-9 sccm with a constant argon flow rate of 20 secm. For the films obtained, the sheet resistance and the chemical binding energy of the films was observed by four-point-probe method and x-ray photoelectron spectroscopy(XPS) depth profiling respectively. In addition, we investigated the relationship between the surface resistance and the chemical nature of the films.

• Laser Solutions
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• v.17 no.4
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• pp.14-19
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• 2014

Laser beam was applied on the boundary of the polyurethane and biodegradable polyacetate polymers. The distributed laser passed through the polyurethane layer and heated the polyacetate layer, then the soften acetate was squeezed thorough the 1mm square slots of polyurethane for the mechanical joining. The surface roughness ranging between $0.28{\mu}m$ and $3.06{\mu}m$ had almost no effect on joining strength, but the optical properties of HD (High Definition) and UHD (Ultra High Definition) mode affected laser beam transmittance. The optimum laser power was found to be between 8watt and 10watt with 500mm/min of scanning speed. The joining boundary was characterized by optical and SEM analysis. Based on the experiment and characterization results, the laser energy was effective for the polymer joining and efficiency of joining.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.242-248
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• 2008

The structural, optical and electrical properties of ZnO films doped with 1.5 at% of 3A materials(B, Al, Ga, In) were studied by sol-gel process. The films were found to be c-axis (002) oriented hexagonal structure on glass substrate, when post heated at 500 $^{\circ}C$. The surface of the films showed a uniform and nano size microstructure and the crystalline size of doped films decreased. The lattice constants of ZnO:B/Al/Ga increased than that of ZnO, while ZnO:In decreased. All the films were highly transparent(above 90 %) in the visible region. The energy gaps of ZnO:B/Al/Ga were increased a little, but that of ZnO:In was not changed. The resistivities of ZnO:Al/Ga/In were less than 0.1 $\Omega$cm. All the films showed a semiconductor properties in the light or temperature, however ZnO:In was less sensitive to it. A figure of merit of ZnO:In had the highest value of 0.025 $\Omega^{-1}$ in all samples.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1107-1113
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• 2004

Dry film method for large size of PDP(Plasma Display Panel) module has been actively investigated. This method for lead-free transparent dielectric formation depends on green sheet technology. By adjusting the composition of transparent dielectric powders and organics, uniformly dispersed slurry was fabricated, Viscosity of the slurry exhibited pseudoplastic behavior for tape casting, Cast green sheets were tested under tensile condition at room temperature. It was found that the increase in transparent dielectric powder and binder ratio leads to decrease in strain to failure of green sheets from 120 % to 34 % and from 255 % to 4 %, respectively. Tensile strength of green sheets decreased abruptly with increase of transparent dielectric powder ratio, with minimum at 0.13 MPa. On the other hand, tensile strength increased continuously from 0.1 MPa to 2.4 MPa with increase of binder ratio. The green sheets were attached on the glass substrate and heated by following firing schedule. As a result, the best result was obtained when fired at 580 $^{\circ}C$ for 15 min and had transmittance of 78 % in visible range 550 nm.

• Design & Manufacturing
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• v.2 no.1
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• pp.45-50
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• 2008

Micro channel is to fabricate desired pattern on the polymer substrate by pressing the patterned mold against the substrate which is heated above the glass transition temperature, and it is a high throughput fabrication method for bio chip, optical microstructure, etc. due to the simultaneous large area patterning. However, the bad pattern fidelity in large area patterning is one of the obstacles to applying the hot embossing technology for mass production. In the present study, stamper of cross channel with width $100{\mu}m$ and height $50{\mu}m$ was manufactured using UV-LiGA process. Micro channel was manufactured using stamper manufactured in this study. Also replicability appliance was evaluated for micro channel and factors affected replicability were investigated using Taguchi method.

• Transactions of Materials Processing
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• v.29 no.4
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• pp.179-187
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• 2020

Existing composite forming processes such as the autoclave, prepreg compression forming (PCF), RTM, etc. require high production costs because of their long processing time. On the other hand, microwave heating process (MHP) can reduce the production costs since both mold and composite material can be heated directly. The aim of this study is to manufacture a mold consisting of polytetrafluoroethylene (PTFE), quartz glass, stainless steel clamps, and polyether ether ketone (PEEK) bolts for fabricating FML based on self-reinforced polypropylene (SRPP) using the MHP. First, the flame test was carried out prior to the MHP to check the temperature on the mold and whether the spark occurred at the mold and the edge of the FML. Second, the uniaxial tensile test was then conducted to obtain the mechanical properties of the FML manufactured by the MHP. The mechanical properties were compared with those of the FML fabricated by the PCF. As a result, the MHP using the PTFE mold can manufacture the FML more rapidly than the PCF, and obtain acceptable mechanical properties.

• Transactions on Electrical and Electronic Materials
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• v.11 no.4
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• pp.174-177
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• 2010

We have developed an environment-friendly etching process, an alternative to the dichromic acid etching process, as a pretreatment of acrylonitrile-butadiene-styrene (ABS) plastic for electroless plating. In order to plate ABS plastic in an electroless way, there should be fine holes on the surface of the ABS plastic to enhance mechanically the adhesion strength between the plastic surface and the plate. To make these holes, the surface was coated uniformly with dispersed chemical foaming agents in a mixture of environmentally friendly dispersant and solvent by the methods of dipping or direct application. The solvent seeps into just below the surface and distributes the chemical foaming agents uniformly beneath the surface. After drying off the surface, the surface was heated at a temperature well below the glass transition temperature of ABS plastic. By pyrolysis, the chemical foaming agents made fine holes on the surface. In order to discover optimum conditions for the formation of fine holes, the mixing ratio of the solvent, the dispersant and the chemical foaming agent were controlled. After the etching process, the surface was plated with nickel. We tested the adhesion strength between the ABS plastic and nickel plate by the cross-cutting method. The surface morphologies of the ABS plastic before and after the etching process were observed by means of a scanning electron microscope.

• Journal of the Korean institute of surface engineering
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• v.37 no.3
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• pp.146-151
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• 2004

Indium tin oxide (ITO) is widely used to make a transparent conducting film for various display devices and opto-electric devices. In this study, ITO films on glass substrate were fabricated by inductively coupled plasma (ICP) assisted dc magnetron sputtering. A two-turn rf coil was inserted in the process chamber between the substrate and magnetron for the generation of ICP. The substrates were not heated intentionally. Subsequent post-annealing treatment for as-deposited ITO films was not performed. Low-temperature deposition technique is required for ITO films to be used with heat sensitive plastic substrates, such as the polycarbonate and acrylic substrates used in LCD devices. The surface roughness of the ITO films is also an important feature in the application of OLEDs along with the use of a low temperature deposition technique. In order to obtain optimum ITO thin film properties at low temperature, the depositions were carried out at different condition in changing of Ar and $O_2$ gas mixtures, ICP power. The electrical, optical and structural properties of the deposited films were characterized by four-point probe, UV/VIS spectrophotometer, atomic force microscopy(AFM) and x-ray diffraction (XRD). The electrical resistivity of the films was -l0$^{-4}$ $\Omega$cm and the optical transmittance in the visible range was ＞85%. The surface roughness ( $R_{rms}$) was -20$\AA$.>.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.9
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• pp.605-613
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• 2010

Double skin facade(DSF) ventilated by fans consists of a normal external and an internal envelope. In this glass layer, the installed fan replaces an air inlet for the control of air flow through the cavity. The purpose of this paper is to investigate physical theory and to analyze the applicability of fans installed in a DSF. The experiment was conducted in 2 rooms. One room has a DSF with installed fans and the other one has a typical window. The room ventilated through a DSF which fans are installed was always kept warmer than the other room, ventilated directly from the outdoors. The average increase of the supplied air temperature through the DSF ventilated by fans was $6.54^{\circ}C$ at 78CMH, $6.2^{\circ}C$ at 95CMH, and $3.7^{\circ}C$ at 120CMH. As a result, the DSF with installed fans was appropriate for installation in rooms. It supplies outdoor fresh air heated through a cavity and ventilates a constant air volume.