• Korean Journal of Materials Research
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• v.26 no.2
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• pp.100-108
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• 2016

Zinc Sulfide (ZnS) is one of the II-VI semiconducting materials, having novel fundamental properties and diverse areas of application such as light-emitting diodes (LEDs), electroluminescence, flat panel displays, infrared windows, catalyst, chemical sensors, biosensors, lasers and biodevices, etc. However, despite the remarkable versatility and prospective potential of ZnS, research and development (R&D) into its applications has not been performed in much detail relative to research into other inorganic semiconductors. In this study, based on global patent information, we analyzed recent technical trends and the current status of R&D into ZnS applications. Furthermore, we provided new technical insight into ZnS applicable fields using in-depth analysis. Especially, this report suggests that ZnS, due to its infrared-transmitting optical property, is a promising material in astronomy and military fields for lenses of infrared systems. The patent information analysis in this report will be utilized in the process of identifying the current positioning of technology and the direction of future R&D.

• Environmental Engineering Research
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• v.19 no.3
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• pp.293-298
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• 2014

An anaerobic photosynthetic treatment process utilizing purple non-sulfur photosynthetic bacteria (PNSB) was applied to the recovery of organic carbon from food processing wastewater. PNSB cells, by-product from the treatment, have high nutrition such as proteins and vitamins which are a good alternative for fish feed. Effects of light source on performance of anaerobic photosynthetic process were investigated in this study. Two bench-scale photo-bioreactors were lighted with infrared light emitting diodes (LEDs) and tungsten lamps covered with infrared transmitting filter, respectively, aiming to supply infrared light for photosynthetic bacteria growth. The photo-bioreactors were operated to treat noodle-processing wastewater for 323 days. Hydraulic retention time (HRT) was set as 6 days. Organic removals in the photo-bioreactor lighted with infrared LEDs (91%-95%) was found higher than those in photo-bioreactor with tungsten lamps with filter (79%-83%). Biomass production in a 150 L bench-scale photo-bioreactor was comparable to a 8 L small-scale photo-bioreactor in previous study, due to improvement of light supply efficiency. Application of infrared LEDs could achieve higher treatment performance with advantages in energy efficiency and wavelength specifity.

• The Journal of the Korea Contents Association
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• v.11 no.5
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• pp.205-215
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• 2011

Films are sensitive to ultraviolet rays and in contrast, digital camera sensors are extremely sensitive to infrared rays due to the differences in spectral characteristics. As a result, all digital cameras that use CCD or CMOS are equipped with IR Cut-Off Filter on the overall sensor. Complete block out of infrared rays is ideal, but the actual experiment results showed that infrared rays were not being blocked out completely. Infrared permeability was also different for each camera. Therefore, this study aims to analyze the effect of the minute quantities of infrared rays, which get transmitted due to mechanical properties of IR Cut-Off Filters that are installed on digital cameras, on digital picture images. The results obtained by carrying out a comparative analysis of a UV Filter (infrared transmitting state) and a UV-IR Filter (infrared blocked out state) are as follows. It was confirmed that the minute quantities of infrared rays do affect dynamic range and resolution to some extent, despite the little or no difference in noise and color reproduction.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.22-28
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• 2012

Transparent dye-sensitized solar cells have been widely investigated for the application to building integrated photovoltaic system. Thin film Si-based solar cells are emerging as a substitute for the dye-sensitized solar cells because their merits of well-established manufacturing processes. Since the selective transmitting layer transmits visible light and reflects infrared light, the solar cell efficiency increases with the introduction of the selective transmitting layer. In this work, AlTiO thin films were grown as the selective transmitting layer by cost-effective sputter deposition and their transmittances were improved by controlling deposition parameters.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.40-47
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• 1998

This paper presents the physiological signal processing CMOS one chip for transmitting human bodys small electrical signals such as electrocardiogram(EKG) or electromyogram(EMG) and the external system for receiving signals was implemented by the commercial ICs. For simultaneous four-subject four-channel telemetry, a new enfored synchronization techniqeu using infrared bi-directional communication has been proposed. The telemeter IC with the size of 5.1*5.1mm$^{2}$ has the following functions: receiving of command signal, initialization of internal state of all functional blocks, decoding of subject-selection signal, time multiplexing of 4-channel modulated physiological signals, transmitting of telemetry signal to external system and auto power down control. The newly designed synchronized oscillator with low supply voltage dependence in the telemeter IC operates at a supply voltage from 4.6~6.0V and the nonlinearity error of PIM modulator was less than 1.2%F.S(full scale). The power saving block operates at the period of 2.5ms even if the telemetry IC does not receive command signal from external system for a constant time.

• Ceramist
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• v.10 no.3
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• pp.48-54
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• 2007

Glass-ceramics transparent above $10\;{\mu}m$ in the infrared, have been synthesized. They are based on germanium and antimony sulphides or selenides associated to alkali halides. They are prepared by heating glass samples at temperatures above the glass transition, as a function of time. Ceramisation can be controlled, so that sub-100 nm crystals are generated in the glass matrix. Then, low light scattering is achieved and the transparency window of the original glass is maintained. When gallium sulphide is added, glass ceramics can be doped with rare-earth ions. Emissions from the $^4F_{3/2}$ and $^4I_{13/2}$ of $Nd^{3+}$ and $Er^{3+}$ ions, respectively, are more intense in glass-ceramics, as compared to their vitreous counterpart. Examination of band profiles and decaytimes show that rare-earth ions are embedded in both crystalline and glassy environments.

• Journal of the Optical Society of Korea
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• v.17 no.2
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• pp.142-147
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• 2013

In order to deduce the difficulty of fixing the Ritchey-Chretien (R-C) dual reflective optical system and enhance the stability of the secondary mirror, a compact integral structure is presented here composed of two transmitting and two reflective aspheric surfaces. The four surfaces were manufactured from a single germanium lens and integrated together. The two reflective surfaces formed by coating the inner reflecting films were assembled in one lens. It makes the installation of the two mirrors easier and the structure of the secondary mirror more stable. A design of mid-wave infrared (MWIR) compact imaging system is presented with a spectral range chosen as $3.7-4.8{\mu}m$. The effective focal length is f=90 mm. The field of view (FOV) for the lens is $4.88^{\circ}$. It has good imaging capability with Modulation Transfer Function (MTF) of all field of view more than 0.55 close to the diffraction limitation. Outdoor experiments were carried out and it is shown that the integral catadioptric optical system performs well on imaging.

• Current Optics and Photonics
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• v.7 no.6
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• pp.738-744
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• 2023

Graphene-based saturable absorbers (SAs) are widely used as laser mode-lockers at various laser oscillators. In particular, transmission-type graphene-SAs with ultrabroad spectral coverage are typically manufactured on transparent substrates with low nonlinearity to minimize the effects on the oscillators. Here, we developed two types of transmitting graphene SAs based on CaF₂ and ZnSe. Using the graphene-SA based on CaF₂, a passively mode-locked mid-infrared Cr:ZnS laser delivers relatively long 540 fs pulses with a maximum output power of up to 760 mW. In the negative net cavity dispersion regime, the pulse width was not reduced further by inhomogeneous group delay dispersion (GDD) compensation. In the same laser cavity, we replaced only the graphene-SA based on CaF₂ with the SA based on ZnSe. Due to the additional self-phase modulation effect induced by the ZnSe substrate with high nonlinearity, the stably mode-locked Cr:ZnS laser produced Fourier transform-limited ~130 fs near 2,340 nm. In the stable single-pulse operation regime, average output powers up to 635 mW at 234 MHz repetition rates were achieved. To our knowledge, this is the first attempt to achieve shorter pulse widths from a polycrystalline Cr:ZnS laser by utilizing the graphene deposited on the substrate with high nonlinearity.

• Journal of the Korean Vacuum Society
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• v.22 no.1
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• pp.13-19
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• 2013

It is expected that progress in building-integrated photovoltaic (BIPV) systems, improving the functionality and design of buildings, will be accelerated in the coming years. While the dye sensitized solar cell is considered one of the most important technologies in the BIPV field, the transparent silicon based thin film solar cell fabricated by thin film processes has drawn attention as a novel alternative. When the selective transmitting layer is applied to the solar cell, the conversion efficiency is improved due to the re-reflection of infrared light into an absorber layer with the transmission of visible light through the solar cell. In this work, we prepared Al-Ti based oxide thin films using cost-effective sputter deposition and examined their selective transmitting characteristics with various compositions. The transmittance and reflectance of the Al-Ti based oxide thin film changed with the variation of its composition, and the selective transmitting property was observed in the sample with the 25 nm-thick AlTiO layer. It is considered that the realization of transparent solar cells and the improvement of their conversion efficiency can be achieved by introducing the Al-Ti based selective transmitting layer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.9
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• pp.784-790
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• 2012

In this paper, we propose a upstream transmission method to extend coverage in visible light communication (VLC) systems. We extend transmission distance by using focused infrared(IR) light emitting diodes(LEDs). Since the focused light covers just limited area, it might have a difficulty in transmitting data if the transmitter and receiver are not properly aligned. To solve this problem, we arrange multiple IR-LEDs in different direction and select a single best performing IR-LED among multiple IR-LEDs. Also, the transmission performance is periodically checked and another IR-LED is reselected to support the required quality of service (QoS) and to minimize battery consumption required by a mobile terminal.