• Journal of Radiation Protection and Research
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• v.43 no.4
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• pp.131-136
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• 2018

Background: We investigated the current characteristics of a thin-film Ag electrode on a chemical vapor deposition (CVD) diamond. The CVD diamond is widely recognized as a radiation detection material because of its high tolerance against high radiation, stable response to various dose rates, and good sensitivity. Additionally, thin-film Ag has been widely used as an electrode with high electrical conductivity. Materials and Methods: Considering these properties, the thin-film Ag electrode was deposited onto CVD diamonds with varied deposition thicknesses (${\fallingdotseq}50/98/152/257nm$); subsequently, the surface thickness, surface roughness, leakage current, and photo-current were characterized. Results and Discussion: The leakage current was found to be very low, and the photo-current output signal was observed as stable for a deposited film thickness of 98 nm; at this thickness, a uniform and constant surface roughness of the deposited thin-film Ag electrode were obtained. Conclusion: We found that a CVD diamond radiation detector with a thin-film Ag electrode deposition thickness close to 100 nm exhibited minimal leakage current and yielded a highly stable output signal.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.46-52
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• 1995

This paper proposes methodologies for the development of radiation thermometer using InSb photo-detector of which spectral sensitivity is excellent over the wave length range of 2 .mu. m .approx. 5 .mu. m. The proposed radiation thermometer has broad measurement range from normal to high, up to more than 1000 .deg. C, with high accuracy, and can measure temperature on the material surface or heat emission noncontactely with high speed. Optical system was consisted of two convex lens with foruslength of 15.2mm for infrared lay focusing, Ge filter to cut the short wave length components and sapphire filter to cut the long wave length components. The cold shielded was installed in the whole surface of the light-absorbing element to remove the error- mometer, calibration using black body furnace which has temperature range of 90 .deg. C .approx. 1100 .deg. C was carried out, and temperature calaibration curve was obtained by exponential function curvefitting. The result shows maximum error less than 0.24%(640K .+-. 1.6K) over the measurement range of 90 .deg. C .approx. 700 .deg. C, and from this result the usefulness of the developed thermometer has been confirmed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.186-189
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• 2001

The main method in micro-etching process, used in manufacturing semiconductors, electronic components, circuits, is Photo Masking method that exposes and develops on the photo-sensitivity solutions or films. This method enables one to process highly precisely, $\pm$0.03 mm in end line location area. But this has limits in a high speed / wide width process, difficulties in endless masking, and the problem of high price. We have developed the direct masking method to make use of Gravure printing, widely used in grocery packing sheet printing. We made cylinder tools to influence the masking quality by laser stream process. We have confirmed that the end line location accuracy in the line width of the product is improved from 0.12 mm to $\pm$0.07 mm level, after etching process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.267-267
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• 2010

The structural and electrical properties of microcrystalline silicon films were investigated by hot wire chemical vapor deposition(HWCVD) often called catalytic chemical vapor deposition(Cat-CVD). The Si microcrystalline phase is easily controlled by changing the rate of the silane concentration of $SiH_4$ to $H_2$ during deposition. The Structural property was observed by Raman and SEM. Photo-conductivity and dark conductivity, and photo-sensitivity were observed by Sunsimulator (AM 1.5 illumination). The film color was changed by the variation of silane concentration. HWCVD is useful for the formation of Si thin films for solar cell and needs further commercialized development for mass production.

• Journal of Biosystems Engineering
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• v.17 no.4
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• pp.404-409
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• 1992

It is important to measure the somatic informations for stockbreeding automatization. This study was carried out for the development of wireless measurement system of sphygmus in living animals. In meauring sphygmus counting with the single-channel telemety system, a LED-photo transistor sensor showed more sensitivity to the change of blood pressure than a piezo-electric sensor based pressure sensor. The LED-photo transistor sensor resulted ${\pm}1.29%$ of measurement error of sphygmus counting. In the process of transmitting and receiving the blood pressure signal for counting sphygmus, noises were mixed with, and the noises made the counting almost impossible. Auto-correlation analysis technique was applied to the signal data to extract the sphygmus information, and the technique was proved to be very effective.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.203-208
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• 1999

By tilting the reference mirror of Twynman-Green interferometer having a reference mirror and a moving mirror, firinge pattern composed of bright and dark parallel lines can be obtained and the fringe pattern is shifted according to the displacement of the mowing mirror. Several studies are executed for displacement measurement by detecting the intensity of the fringe with photo-diodes having small detecting area. In this study, to improve the sensitivity and robustness, the intensity of fringe is detected by using a large-area quadratic photo-diode masked with a grating panel having four kinds of binary grating having phase-difference of 0, {\pi}$/4, {\pi}$/2, 3 {\pi}$/4. The phase of the fringe is calculated with a simple 4-buckets algorithm. A experimental result shows that standard deviation of 5.653 nm is obtained comparing with a capacitive type gap sensor having nearly 1 nm accuracy.

• Journal of Photoscience
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• v.9 no.2
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• pp.162-165
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• 2002

Rice is widely cultivated in various regions throughout Asia. Over a five-year period, we investigated the effects of supplemental UVB radiation on the growth and yield of Japanese rice cultivars in the field. The findings of that study indicated that supplemental UVB radiation has inhibitory effects on the growth and grain development. Furthermore, we investigated the sensitivity to UVB radiation of rice cultivars of 5 Asian rice ecotypes, and found that rice cultivars vary widely in UVB sensitivity. The aim of our study is improving UVB resistance in plants by bioengineering or breeding programs. In order to make it, there is need to find the molecular origin of the sensitivity to UVB. Cyclobutane pyrimidine dimer (CPD) is major UV-induced DNA lesions. Plants possess two mechanisms to cope with such DNA damage. The first is the accumulation of UV-absorbing compounds. Our previous data showed that the steady-state CPD levels in leaves of rice grown under chronic radiation in any culture were not so greatly influenced by the increased UV-absorbing compounds content, although there was a significant positive correlation between the CPD levels induced by challenge UVB exposure and the UV-absorbing compounds content. The other is the repair of DNA damage. Photorepair is the major pathway in plants for repairing CPD. We found that the sensitivity to UVB could seriously correlate with the low ability in CPD photorepair in rice plants. These results suggest that photo lyase might be an excellent candidate for restoration by way of selective breeding or engineering in rice.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.143-150
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• 2023

Underwater wireless communication is a challenging issue for realizing the smart aqua-farm and various marine activities for exploring the ocean and environmental monitoring. In comparison to acoustic and radio frequency technologies, the visible light communication is the most promising method to transmit data with a higher speed in complex underwater environments. To send data at a speedier rate, high-performance photodetectors are essentially required to receive blue and/or cyan-blue light that are transmitted from the light sources in a light-fidelity (Li-Fi) system. Here, we fabricated high-performance organic phototransistors (OPTs) based on P-type donor polymer (PTO2) and N-type acceptor small molecule (IT-4F) blend semiconductors. Bulk-heterojunction (BHJ) PTO2:IT-4F photo-active layer has a broad absorption spectrum in the range of 450~550 nm wavelength. Solution-processed OPTs showed a high photo-responsivity >1,000 mA/W, a large photo-sensitivity >10³, a fast response time, and reproducible light-On/Off switching characteristics even under a weak incident light. BHJ organic semiconductors absorbed photons and generated excitons, and efficiently dissociated to electron and hole carriers at the donor-acceptor interface. Printed and flexible OPTs can be widely used as Li-Fi receivers and image sensors for underwater communication and underwater internet of things (UIoTs).

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1319-1322
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• 2007

Planar PIN photodiode is compatible with LTPS process, and its fabrication requires no additional manufacturing process. In this study we design the optimum dimension of PIN diodes with two nitride layers to improve the efficiency of PIN diodes. The PIN photo sensor shows very good sensitivity to ambient light illuminance.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1787-1790
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• 2006

An artificial retina using thin-film photodiodes (TFPDs) and thin-film transistors (TFTs) is proposed. The characteristics of a TFPD and TFTs are measured, and the circuits of the retina pixel and retina array are designed. It is confirmed that the artificial retina can achieve edge enhancement and control photo-sensitivity.