• Journal of the Semiconductor & Display Technology
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• v.12 no.2
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• pp.57-61
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• 2013

This paper presents adaptive neuro-fuzzy inference based defect detection method for various defect types, such as micro-crack, fingerprint and contamination, in heterogeneously textured surface of polycrystalline solar wafers. Polycrystalline solar wafer consists of various crystals so the surface of solar wafer shows heterogeneously textures. Because of this property the visual inspection of defects is very difficult. In the proposed method, we use local binary feature and fuzzy reasoning for defect detection. Experimental results show that our proposed method achieves a detection rate of 80%~100%, a missing rate of 0%~20% and an over detection (overkill) rate of 9%~21%.

• Journal of the Semiconductor & Display Technology
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• v.11 no.3
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• pp.1-6
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• 2012

In this paper, inspection system based on optical scanning mechanism is designed and developed for solar cell wafer. It consists of optical scanning mechanism, NIR camera optics, machinery and control system, algorithm of defect detection and software. Optical scanning mechanism is composed of geometrical camera optics and structured hybrid illumination system. It is used to inspection of surface defects. NIR camera optics is used for inspection of defects inside solar cell wafer. It is shown that surface and internal micro defects can be detected in developed inspection system for solar cell wafer.

• Journal of the Semiconductor & Display Technology
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• v.19 no.2
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• pp.77-81
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• 2020

Silicon wafer etching in micro electro mechanical systems (MEMS) fabrication is challenging to form 3-D structures. Well known Si-wet etch of silicon employs potassium hydroxide (KOH), tetramethylammonium hydroxide (TMAH) and sodium hydroxide (NaOH). However, the existing silicon wet etching process has a fatal disadvantage that etching of the back side of the wafer is hard to avoid. In this study, a wet etching bath for 150 mm wafers was designed to prevent back-side etching of silicon wafer, and we demonstrated the optimized process recipe to have anisotropic wet etching of silicon wafer without any damage on the backside. We also presented the design of wet bath for 300 mm wafer processing as a promising process development.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.216-220
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• 1987

A graphic display and operator console system is developed for monitoring the operation of power plant. It has multiprocessor structure using VME bus and common memory. The graphic monitoring system is applied to fault tolerant control system for enhancing reliability of boiler analog controller. As a result, it displays all the operating date as color graphic images with 14 pages. Moreover, it can transfer the operator commands to the other micro-processors through common memory.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.555-556
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• 2007

This paper proposes a new concept's IDSFHA(Intelligent Digital Switchgear For Home Automation) which can obtain the safety, the reliability and the easy to correspond to the request of the general electric customer or electric power company under the ubiquitous-based home automation environments The IDSFHA is designed by analyzing their requirement functions, a 32-bit micro processor is adopted as main controller to support efficiently the designed functions. The single phase power IC(ADE7753) is utilized to collect the electric power information, and makes it possible to communicate as internet among the IDSFHA and their using the ethernet convertor. In the proposed IDSFHA, the several functions are implemented such as the earth leakage level display and waveform transmitting, the electric power using fee display, voltage management, load management and load control function. Finally, the prototype of the IDSFHA is made experimently based on the designed results.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.113-118
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• 1989

By using the single mode optical fiber, we fabricated Fiber-optic Fabry-Perot interferometer (FFPI). The change over a wide range in the optical path length of a FFPI is observed. The temporal movement of the interference fringes by external condition to P.Z. T) is converted to circular motion on an oscilloscope display and then recorded with a micro-computer. The two output voltages of the D/A converters are applied to X and Y terminals of oscilloscope to display circular motion on oscilloscope. Thus the direction of phase shift can be determined with observing the direction of circular motion. The variation of the optical length can be measured by calculating the angle of spot of circle with an accuracy of λ/90 wave length due to variation of temperature in this system 2.7x10-4$^{\circ}C$.

• Journal of the Semiconductor & Display Technology
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• v.17 no.1
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• pp.50-53
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• 2018

Cyclic measurement system using relay circuit for organic light emitting diode (OLED) was demonstrated. The OLED characterization such as current-voltage, impedance, and capacitance-voltage is performed in sequence, repetitively and automatically under full control of the personnel computer (PC) without changing the connection of cables. Owing to in situ degradation by cyclic measurement, the time dependence of the data can give good information on the reliability factor of the OLED devices. Therefore, both performance and reliability of the OLEDs can be evaluated, with no manual operation during the entire process.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.36-40
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• 2017

In this paper, a new method of laser trimming of thick film heater is studied. Various laser waves (IR, Green, UV) are used to ablation the heater and the process parameters are also presented. For given initial printed resisters, the cutting length should be prepared to obtain the target resister value in advance. Therefore, the cutting model is very important. The well-known model was tested and proven that it is valid only within a certain range of cutting length. A new model is proposed for a wide range of resister laser trimming. The cutting lengths and resister variation was obtained and formulated. To verify the presented method, the cutting lengths of each resister are calculated for various target resister value and laser trimming using UV is conducted.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1663-1674
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• 2018

We propose the Poynting vector analysis of the air mode in a top-emitting organic light-emitting diode (OLED) by combining the transfer matrix method and dipole source term. The spatial profiles of the time-averaged optical power flow of the air mode are calculated inside and outside the multilayer structure of the OLED with respect to the thickness of the semi-transparent top cathode and capping layer (CPL). We elucidate how the micro-cavity effect controlled by the thickness variation of the semi-transparent top cathode or CPL affects the internal optical power and absorption loss inside the OLED multilayer and the external optical power coupled into the air. When the calculated absorption loss and external power obtained by the proposed Poynting vector and currently-used point dipole models are compared, two calculation results are identical, which demonstrates the validity of the two models.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.87-91
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• 2021

Various Cu ions are discharged into water from various industries, which results in a severe trouble for groundwater, soil, air, and eventually animals and humans. In this work, graphene oxide (GO) is introduced as a Cu removal absorber and the real-time monitoring method is demonstrated. The results show that GO is a very effective material to absorb Cu ions in the solution. In addition, the residual Cu ions in the solution is monitored via optical transmittance method, which well match with Inductively Coupled Plasma Mass Spectrometer (ICP-MS) analysis.