• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.261-268
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• 2014

Precision screws have a wide range of industrial applications such as electrical and automotive products. To produce screw threads with high precision, not only high precision manufacturing technology but also reliable measurement technology is required. Machine vision systems have been used in the automatic inspection of screw threads based on backlight illumination, which cannot detect defects on the thread surface. Recently, an omnidirectional inspection system for screw threads was developed to obtain $360^{\circ}$ images of screws, based on front light illumination. In this study, the illumination design for the omnidirectional inspection system was modified by adding a light shield to improve the image uniformity. Optical simulation for various shield designs was performed to analyze image uniformity of the obtained images. The simulation results were analyzed statistically using response surface method, from which optical performance of the omnidirectional inspection system could be optimized in terms of image quality and uniformity.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.190-198
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• 2010

Asymmetric model for plasma uniformity by Ar and $CF_4$ was modeled by the antenna structure, the diameter of chamber, and the distance between source and substrate for the development of plasma equipment for 450 mm wafer. The aspect ratio of chamber was divided by diameter, distance from substrate, and pumping port area. And we found the condition with the optimized plasma uniformity by changing the antenna structure. The drift diffusion and quasi-neutrality for simplification were used, and the ion energy function was activated for the surface recombination and etching reaction. The uniformity of plasma density on substrate surface was improved by being far of the distance between substrate wall and chamber wall, and substrate and plasma source. And when the antenna of only 2 turns was used, the plasma uniformity can improve from 20~30% to 4.7%.

• Journal of the Korean Vacuum Society
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• v.4 no.S1
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• pp.190-195
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• 1995

The feature scale model for selective chemical vapor deopsition process was proposed and the simulation was performed to study the selectivity and uniformity of deposited thin film using Monte Carlo method and string algorithm. The effect of model parameters such as sticking coefficient, aspect ratio, and surface diffusion coefficient on the deposited thin film pattern was improved for lower sticking coefficient and higher aspect ratio. It was revealed that the selectivity loss ascrives to the surface diffusion. Different values of sticking coefficients on Si and on SiO2 surface greatly influenced the deopsited thin film profile. In addition, as the lateral wall angle decreased, the selectively deposited film had improved uniformity except the vicinity of trench wall. The optimum eondition for the most flat selective film deposition pattern is the case with low sticking coefficient and slightly increased surface diffusion coefficient.

• Journal of the Korean institute of surface engineering
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• v.41 no.6
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• pp.279-286
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• 2008

Numerical analysis is done to investigate which would be the most influencing process parameter in determining the uniformity of deposition thickness in TiN ICP-CVD(inductively coupled plasma chemical vapor deposition). Two configurations of ICP antenna are modeled; side and top planar. Side and top gas inlets are considered with each ICP antenna geometries. Precursor for TiN deposition was TDMAT(Tetrakis Diethyl Methyl Amido Titanium). Two step volume dissociation of TDMAT is used and absorption, desorption and deposition surface reactions are included. Most influencing factors are H and N concentration dissociated by electron impact collisions in plasma volume which depends on the relative positions of gas inlet and ICP antenna generated hot plasma region. Low surface recombination of N shows hollow type concentration, but H gives a bell type distribution. Film thickness at substrate edges is sensitive to gas flow rate and at high pressures getting more dependent on flow characteristics.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.635-639
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• 2007

In this study, optimal design and test of flat-plate heat pipe were carried out in order to improve both thermal response and surface temperature uniformity of heating plate. Experimental results show that the thermal response of flat-plate heat pipe is faster than that of a conventional heating type ones along with less weight and cost. The surface temperature uniformity is also improved.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.116-120
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• 2017

Temperature uniformity of a wafer in a semiconductor process is a very important factor that determines the overall yield. Therefore, it is very important to confirm the temperature characteristics of the chuck surface on which the wafer is lifted. The temperature characteristics of the chuck depend on the external heat source, the shape of the cooling channel inside the chuck, the material on the chuck surface, and so on. In this study, CFD confirms the change of temperature characteristics according to the stacking order of ceramic materials on the chuck surface, and suggests the best lamination method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.111-114
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• 2003

In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternating field vertically to the EPD field has been developed for the first time and applied to the electrophoretic deposition process. The applied alternating electric field caused a force to be exerted on each YBCO particle and resulted in a shaking of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. The usual commercial electrical power was used for the vertically applied alternating voltage and the induced electric field was 25-120 V/cm at 60Hz. The thick film fabricated by the method developed in this paper showed better surface uniformity without crack and porosity and improved film characteristics such as critical temperature ($T_{c,zero}$ : 90 K) and critical current density ($2354\;A/cm^2$). Therefore, it is expected that the shaky-aligned electrophoretic deposition method can be used to fabricate superconductor films through a simpler process and at less expense.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.1041-1046
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• 2003

In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternating field vertically to the EPD field has been developed for the first time and applied to the electrophoretic deposition process. The applied alternating electric field, so called Shaky Alternating Assisted Field, caused a force to be exerted on each YBCO particle and resulted in a shaking of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. The usual commercial electrical power was used for the vertically applied alternating voltage and the induced electric field was 25-120 V/cm at 60Hz. The thick film fabricated by the method developed in this paper showed better surface uniformity without crack and porosity and improved film characteristics such as critical temperature (Tc,zero = 90 K) and critical current density (2354 A/$\textrm{cm}^2$), Therefore, it is expected that the shaky-aligned electrophoretic deposition method can be used to fabricate superconductor films through a simpler process and at less expense.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3714-3721
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• 2015

Although sheath-type heating line is generally used for susceptor heater, performance deterioration problems in temperature uniformity occurs in the case of large scale and high temperature condition. We developed new design and prototype of the susceptor using sheet metal to provide performance improvement in temperature uniformity. Temperature uniformity below 1.4% in the surface temperature condition of $450^{\circ}C$ was verified in the susceptor prototype. Also we developed Kernel regression algorithm to estimate measured temperature using temperature learning data. The reliability of the measured temperature uniformity was confirmed by comparative analysis between predicted data and measured data.

• Laser Solutions
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• v.10 no.1
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• pp.29-34
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• 2007

We propose a novel application of laser engraving to patterning of light guide panel (LGP) for backlight. The feasibility of three-dimensional engraved pattern in the LGP was verified by measuring brightness and uniformity. To improve the overall uniformity, we have modified proposed patterns and found improved design for patterns. The tailoring of pattern by using laser engraving method could endow the controllability of uniformity. The proposed LGPs are more efficient in both average brightness and uniformity of illumination than the conventional LGPs which have surface pattern on the panel.