• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.33-37
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• 1999

We present, for the first time, a prototype active-matrix field emission display (AMFED) with 25$\times$25 pixels in which polycrystalline silicon fie이 emitter array (poly-Si FEA) and thin-film transistor (TFT) were monolityically intergrated on an insulating substrate. The FEAs showed relatively large electron emissions above at a gate voltage of 50 V, and the TFTs were designed to have low off-stage currents even though at high drain voltages. The intergrated poly-Si TFT controlled electron emissions of the poly-Si FEA actively, resulting in improvement in the emission stability and reliability along with a low-voltage control of field emission below 25V. With the prototype AMFED we have displayed character patterns by low-boltage pertipheral circuits of 15 V in a high vacuum chamber.

• Journal of Sensor Science and Technology
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• v.21 no.3
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• pp.186-191
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• 2012

In this paper, we present a pH measurement method that uses a microcantilever-array-based biosensor system. It is composed of microcantilever array, liquid cell, micro syringe pump, laser diode array, position sensitive detector, data acquisition device, and data processing software. Four microcantilevers are functionalized with pH-sensitive MHA(mercaptohexadecanoic acid) as a probe, while three microcantilevers are functionalized with HDT(hexadecane thiol) as reference. We prepare PBS(phosphate buffered saline) solutions of different pH and inject them into the liquid cell with a predefined volumetric speed at regular time intervals. The functionalized mircocantilevers in the liquid cell deflect as a self-assembled monolayer on the microcantilever binds with probe molecules in the solution. The difference in deflection between the MHA-covered probe microcantilever and the HDT-covered reference microcantilever was used to compensate for thermal drift. The deflection difference clearly increases with increasing pH in the solution. It was shown that when the pH values of the PBS solutions are high, there were large variations in the deflection of microcantilevers, whereas there were small variations for low pH value. The experimental results show that the microcantilever array functionalized with MHA and HDT can detect pH value with good repeatability.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1281-1286
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• 2012

In the information age, internet was developed from the wired access to the wireless Internet access. When a surge in demand for wireless Internet access, efficiency and performance of 2.4GHz band which leads to saturation of the communication was significantly fall. in this paper, the U-slot microstrip array antenna in the 5 GHz band have been studied to improve the drawback of a narrow bandwidth of the T-slot micro strip antenna. The characteristics of single antenna and array antenna was investigated to obtain the optimum frequency properties. The optimal U-slot microstrip array antenna possibility was confirmed.

• Journal of Sensor Science and Technology
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• v.17 no.6
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• pp.406-413
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• 2008

We have been implemented simple statistical pattern recognition methods for harmful gases classification using gas sensors array fabricated by MEMS (Micro Electro Mechanical System) technology. The performance of pattern recognition method as a gas classifier is highly dependent on the choice of pre-processing techniques for sensor and sensors array signals and optimal classification algorithms among the various classification techniques. We carried out pre-processing for each sensor's signal as well as sensors array signals to extract features for each gas. We adapted simple statistical pattern recognition algorithms, which were PCA (Principal Component Analysis) for visualization of patterns clustering and MLR (Multi-Linear Regression) for real-time system implementation, to classify harmful gases. Experimental results of adapted pattern recognition methods with pre-processing techniques have been shown good clustering performance and expected easy implementation for real-time sensing system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.04a
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• pp.7-13
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• 2003

Microlens arrays were fabricated using a novel fabrication technology based on the exposure of a PMMA (Polymethylmethacrylate) sheet to deep X-rays and subsequent thermal treatment. X-ray irradiation causes the decrease of molecular weight of PMMA, which in turn decreases the glass transition temperature and consequently causes a net volume increase during the thermal cycle resulting in a swollen microlens. A new physical modeling and analyses for micro lens formation were presented according to experimental procedure. A simple analysis based on the new model is found to be capable of predicting the shapes of micro lens which depend on the thermal treatment. For the replication of micro lens arrays having various diameters with different foci on the same surface, the hot embossing and the microinjection molding processes has been successfully utilized with a mold insert that is fabricated by Ni-electroplating based on a PMMA microstructure of micro lenses. Fabricated microlenses showed good surface roughness with the order of 1nm.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3378-3382
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• 2012

A superhydrophobic surface with a water contact angle > $150^{\circ}$ has attracted great interest from both fundamental and practical aspects. In this study, we demonstrated that hydrophobicity of a silica nanotube (SNT) array can be easily controlled by the SNT aspect ratio. In addition, the adhesive and anti-adhesive properties were controlled without modifying the hydrophobic surface. Various silica structures on a polydimethylsiloxane substrate were prepared using the desired alumina template. Bundle-arrayed and bowl-arrayed silica surfaces exhibited extraordinary superhydrophobicity due to the large frontal surface area and hierarchical micro/nanostructure. As the strategy used in this study is biocompatible and a wide range of hydrophobicities are capable of being controlled by the SNT aspect ratio, a hydrophobic surface composed of an SNT array could be an attractive candidate for bioapplications, such as cell and protein chips.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.238-239
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• 2009

The amorphous silicon microbolometer array has been developed by the MEMS design and fabrication technology. Before the bolometer array for the image sensor being designed, the structure of unit cell and $16\times16$ array of it was simulated, designed and fabricated. The properties of bolometer have been measured as such that the TCR -3%/K.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1488-1491
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• 1987

This paper describes 16-point FFT processor using systolic array and its implementation into VLSI. Designed FFT processor executes FFT/IFFT arithmetic under mode control and consists of cell array, array controller and input/output buffer memory. For design for testibility, we added built-in self test circuit into designed FFT processor. To verify designed 16-point FFT processor, logic simulation was performed by YSLOG on MICRO-VAXII. From the simulation results, it is estimated that the proposed FFT processor can perform 16-point FFT in about 4400[ns].

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.723-726
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• 2002

This paper describes the design, fabrication, and measurement of a sequential-rotation microstrip-array antenna for the Electronic Toll Collection System (ETCS). The ETCS is made possible by using roadside equipment with radiation pattern that can accurately pinpoint the designated communication area, without interference from other lanes. The sequential-rotation microstrip-array antenna was applied to the absorber to reduce the side lobe level (SLL). Results showed that the antenna yields a return loss at a center frequency of -20.675 dB, an axial ratio of 1.15 dB, and a gain of 20.26 dBi.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.538-545
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• 2014

Microlens array (MLA) films have been used as brightness-enhancement components in many illumination systems, such as a backlight, which should meet the industrial needs of low cost and high brightness performance. A hexagonally-arranged MLA (HA-MLA) was chosen due to its high filling factor, which was a prerequisite for achieving high brightness-enhancement capability. The moir$\acute{e}$ fringes produced in a film stack composed of two HA-MLA were investigated, under four different lens configurations, by optical simulation. It was found that randomizing the lens configuration, while keeping the filling factor high, was effective way to develop high-gain MLA films for backlight applications.