• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.3
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• pp.93-101
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• 1998

In Integrated Tube Components(ITC) process in themanufacturing of color display tube, we describe the necessity of the convergence measurement method using photo sensors. Compared with methods using 1D or 2D cameras, its characteristics is to use of moving image patterns and fixed sensors. This measurement method is formulated as the measurement problem of the phase difference in phase changing periodic signals. The convergence measurement system using photo sensors, for the good performance, must have a small standard deviation for the repetitive measurement in the same condition and a fast measurement time for thecovergence change. By above two conditions, we proposed the real time measurement algorithm of the pahse difference using fundametal and harmonic in phase changing periodic signals. And, the proposed algorithm is applied to the convergence measurement system.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.11-16
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• 2010

Wafer Pre-Alignment is to find the center and the orientation of a wafer and to move the wafer to the desired position and orientation. In this paper, an area camera based pre-aligning method is presented that captures 8 wafer images regularly during 360 degrees rotation. From the images, wafer edge positions are extracted and used to estimate the wafer's center and orientation using least squares circle fitting. These data are utilized for the proper alignment of the wafer. For accurate alignments, camera calibration methods using high order polynomials are used for converting pixel coordinates into real-world coordinates. A complete pre-alignment system was constructed using mechanical and optical components and tested. Experimental results show that alignment of wafer center and orientation can be done with the standard deviation of 0.002 mm and 0.028 degree, respectively.

• Journal of the Semiconductor & Display Technology
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• v.8 no.4
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• pp.25-29
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• 2009

In this study, a thin plate-type heat pipe, instead of a solid aluminium heat sink, is used to eliminate heat released from LED components for lighting. Effects of the heat pipe size and installation angle are studied both in numerically and experimentally. According to the results, temperature on LED chip, when a heat pipe is used, is $1.2^{\circ}C$ lower than using the conventional metal PCB. The overall temperature drop is $32^{\circ}C$ if the heat pipe is properly used. The highest cooling performance is obtained in the case when the angle of a heat pipe installation is $90^{\circ}$.

• Journal of the Semiconductor & Display Technology
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• v.12 no.4
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• pp.27-32
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• 2013

In this paper, the boost converter was implemented by digital control in many applications of the step-up. The PWM(pulse width modulation) control module of boost converter was digitized at power converter using the FPGA device and VHDL. The boost converter was designed to output a fixed voltage through the PI control algorithm of the PWM control module even if input voltage and output load are variable. The boost converter was digitized can be simplified by reducing the size of the module and the external control components. Thus, the digital power IC has advantageous for weight reduction and miniaturization of electronic products because it can be controlled remotely by setting the desired output voltage and PWM control module. The boost converter using the digital power IC was confirmed through experiments and the good performances were showed from experiment results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1295-1297
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• 2008

Large-sized flat-panel displays are widely used for PC monitors and TV displays. In this paper, frequency domain pre-filter algorithms are presented for detection of defects in large-sized Thin Film Transistor-Liquid Crystal Display(TFT-LCD) panel surfaces. Frequency analysis with 1-D, 2-D FFT methods for extract the periodic patterns of lattice structures in TFT-LCD is performed. To remove this patterns, frequency domain band-stop filters were used for eliminating specific frequency components. In order to acquire only defected images, 2-D inverse FFT methods to inverse transform of frequency domain images were used.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.1
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• pp.21-29
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• 1997

This paper describes implementation contents contents of manual/automatic complex redundancy control mothod for control of a modulation system of a Paging earth station in redundancy stracture. The existed redundancy control method usually is a automatic local control method in which the redundancy switching, including display or alarm beeping through operation of display devices or audio devices, is performed by the co-action of components or modules when the abnormal status is occurred in a modulation system. However, this method introduced in here is designed to enable use of three control modes;1) Manual mode by an operator, 2) Auto-remote mode by the Network Maagement System, through implementation of the redundancy control system composed of the redundancy control board and the redundancy switching circuit.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.140-145
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• 2001

The tape carrier package(TCD) is one of the most important components in a liquid crystal display(LCD) module. It has a role to transmit electrical signals from a printed circular board(PCB) to a display panel. If TCP is damaged under mechanical shock, the signals can not be transmitted to the panel and as a result, some dead lines are generated on the panel. This kind of phenomenon is commonly called as 'line defects'. In this paper, new structural design concepts of TCP are proposed to guarantee its reliability by using Taguchi's approach and dynamic FE-analysis. The line defects problem of TCP module is solved by replacing the original TCP with the newly designed one.

• Journal of the Semiconductor & Display Technology
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• v.3 no.2
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• pp.5-9
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• 2004

Microcircuit fabrication requires precise control of impurities in tiny regions of the silicon. These regions must be interconnected to create components and VLSI circuits. The patterns to define such regions are created by lithographic processes. In order to image features smaller than 70 nm, it is necessary to employ non-optical technology (or next generation lithography: NGL). One such NGL is extreme ultra-violet lithography (EUVL). EUVL transmits the pattern on the wafer surface after reflecting ultra-violet through mask pattern. If particles exist on the blank mask, it can't transmit the accurate pattern on the wafer and decrease the reflectivity. It is important to care the blank mask. We removed the particles on the wafer using focused ion beam (FIB). During removal, FIB beam caused damage the multi layer mask and it decreased the reflectivity. The relationship between particle removal and reflectivity is examined: i) transmission electron microscope (TEM) observation after particle removal, ii) reflectivity simulation. It is found that the image mode of FIB is more effective for particle removal than spot and bar mode.

• Journal of the Semiconductor & Display Technology
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• v.3 no.2
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• pp.27-33
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• 2004

This paper is concerned with development of a micro tensile testing machine for optical functional materials such as single or poly crystal silicon and nickel film. Two micro tensile testers have been developed for various types of materials and dimensions. One of the testers is actuated by a PZT and the other is actuated by a servo motor for a precise displacement control. The specifications of PZT actuated micro tensile tester developed are as follows: the volumetric size of tester is desktop sized of 710$\times$200$\times$270 $mm^3$; the minimum load capacity and the load resolution in the load cell of 1N are 3 mN and 0.1 mN respectively; the full stroke and the stoke resolution of piezoelectric actuator are 1 mm and 10nm respectively. A special automatic specimen installing equipment is applied in order to prevent unexpected deformation and misalignment of specimens during handling of specimen for testing.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1383-1385
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• 2009

This paper suggests that testing method and equipment structure to detect potential failures of LCD cells. LCD Cell Aging Tester is the unique process to detect failures related with ASG circuits. This system consists of four components that is Aging chamber, work table, probe contact unit, and pattern generator. The key factor of the concept is temperature aging and HVS driving. Complicated combination of test parameters including voltage, temperature and frequency provided practical burn-in conditions eligible for prediction of mass production.