• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.502-505
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• 2003

We synthesized high thermal photoalignment material with hydroxyl aromatic polyimide, and studied the liquid crystal (LC) aligning capabilities on the photopolymer layers. Also, electro-optical (EO) performances for the twisted-nematic (TN)-liquid crystal display (LCD) photoaligned with linearly polarized UV exposure were investigated. A good LC alignment with UV exposure on the photopolymer surface can be obtained. However, the low pretilt angles were obtained below $1^{\circ}$. The Voltage-transmittance (V-T) curve without backflow bounce in the photoaligned TN cell with UV exposure was observed. The response time of photoaligned TN cell was measured about 24 ms.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.816-819
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• 2008

A negative photoresist formulation was developed utilizing synthesized UV monomers containing imide linkage, photoinitiator, UV oligomer, and alkali developable polymer matrix. It was found that via-holes with good resolution, high transmittance and thermal resistance could be obtained by photolithographic process utilizing the negative-type photoresist formulations.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.867-870
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• 2007

In order to solve image sticking phenomena, the gas-phase and liquid-phase interfacial reactions of photosensitive polyimide can annihilate photoreactive carbon-carbon double bonds, which remain after photo-alignment process. The annihilation processes dramatically affect residual DC and photochemical reorientation of photoactive functional groups.

• Macromolecular Research
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• v.14 no.3
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• pp.257-260
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• 2006

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.204-206
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• 1993

In this paper we represented electroplating process without seed layers for making metal micro structures needed for applying terminal voltage for one-to-one cell fusion system. In this system, we need thick insulator and metal structures because the diameter of a cell is approximately $40{\mu}m$. So, we adopted the photo-sensitive polyimide as electroplating molds and structural material. Generally, the processes utilizing the photo-sensitive polyimide as molds have metal seed layers on the substrate as electroplating electrodes and requires wiring tasks to these seed layers. We proposed electroplating process without any seed layer on the Si-substrate and simulated P-N-P (electrode - Si substrate - electrode) junction on N-type silicon substrate. Leakage current from one metal structure to another which arise when terminal voltage is applied can be remarkably decreased by doping Boron in the region to be electroplated.

• Macromolecular Research
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• v.9 no.6
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• pp.327-331
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• 2001

A new soluble photosensitive poly(amide-co-imide) containing p-phenylenediacryloyl moiety was synthesized and its photoreactivity was characterized. The copolymer was synthesized fromp-phenylenediacryloyl chloride, 4,4-(hexafluoroisopropylidene)diphthalic anhydride and two equivalents of bis(4-aminophenyl) ether in NMP with a subsequent chemical imidization of the resulting poly[amide$\xi$ο-(amic acid)] by acetic anhydride and pyridine. The structure and thermal properties of the polymer were characterized by spectroscopic methods and thermal analyses. The polymer was stable up to 350$\^{C}$, showed good solubility in polar aprotic solvents, and became insoluble after UV irradiation due to the[2+2] cycloaddition of phenylenediacryloyl moiety. Photoreactivity of the polymer was investigated in solution or as a film with respect to the various exposure conditions by UV/Vis spectroscopy. The photosensitivity was noticeably increased with the irradiation temperature, especially in the presense of photosensitizer. The reason for the increased sensitivity was speculated based on the flexibilization of main chain at elevated temperature. Exposure characteristic curves were obtained from the gel fraction experiments after UV irradiation. The sensitivity and contrast at 160$\^{C}$ were measured to be 293 mJ/㎠ and 1.64, respectively.

• Journal of Biomedical Engineering Research
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• v.15 no.1
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• pp.1-8
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• 1994

Electrofusion of cabbage protoplasts was performed with a developed equipment which consists of a parallel wire electrode, a AC field generator, and a pulse generator. Exposure of protoplasts to an alternating current field of 450 KHz causes attraction to each other which leads to chains of protoplasts extending from the electrode. Intra-specific protoplast fusion was effectively induced within the pearl chains by the additional application of a single high-intensity DC square wave pulse of 1 KV/cm for 1-3 msec. To improve the performance, micro fusion electrode fabricated from the semiconductor technology and microcontroller based field an, d pulse generator was proposed. The viability of protoplasts after an application of electric field at optimum condition was reduced by only 5 % compared with that of pre-application. A prototype of fusion electrode, which consists of insulator-structure, was successfully fabricated by using photosensitive polyimide.

• Fibers and Polymers
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• v.2 no.1
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• pp.123-130
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• 2001

Photoresponsive side chain copolymer and homopolymer containing an aminonitroazobenzene were synthesized for studying photoisomerization behavior and photo-induced anisotropy. Trans-to-cis photoisomerization was observed under the exposure of a circularly polarized visible light with UV-Vis absorption spectroscopy. Reorientation of polar azobenzene molecules induced optical anisotropy under a linearly polarized light at 532nm. Polarized absorption spectroscopy was employed to investigate the anisotropy of the polymer film during irradiationg of the excitation light. Layers of two photosensitive polymers were used for aligning liquid crystal(LC) molecules instead of one of the rubbed polyimide layers in the conventional twisted nematic cell. For producing homogeneous alignment of a nematic LC molecule, a linearly polarized light was exposed to the films of two polymers. The stability of the LC alignment upon the linearly polarized light exposure was also studied.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.340-346
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• 1994

2.5Gbps 광통신시스템용 수광소자로서 charge plate층을 갖는 링구조의 separate absorption grading multiplication avalanche photodiode를 제작하고 그 특성을 조사 분석하였다. Avalanche Photodiode의 제작은 Metal-Organic Chemical Vapor Deposition 과 Liquid Phase Epitaxy법을 이용한 에피성장과 Br:Methanol을 이용한 채널식각 방법을 사용하였고, passivation과 평탄화는 photosensitive polyimide를 이용하였다. 제작된 ADP는 10nA 이하의 작은 누설전류를 나타내었고, -38~39 V의 항복전압을 나타내었다. 제작된 ADP를 GaAs FET hybrid 전치증폭기와 결합하여 2.5Gbps 속도에서 $2^{23}-1$의 길이를 갖는 입력 광신호에 대해 $ 10^{-10}$ Bit Error Rate에서 -31.0dBm의 수신감도를 얻었다.

• ETRI Journal
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• v.26 no.1
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• pp.61-64
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• 2004

We have explored the fabrication of an InP/InGaAs single heterojunction bipolar transistor (HBT) and a wave guide p-i-n photodiode (PD) on two kinds of double stacked layers for the implementation of an optoelectronic millimeter-wave monolithic integrated circuit (OEMMIC). We applied a photosensitive polyimide for passivation and integration to overcome the large difference between the HBT and PD layers of around $3{\mu}m$. Our experiment showed that the RF characteristics of the HBT were dependent on the location of the PD layer, while the dc performances of the HBTs and PDs were independent of the type of stacked layer used. The $F_t$ and $F_{max}$ of the HBTs on the HBT/PD stacked layer were 10% lower than those of the HBTs on the PD/HBT stacked layer.