• Journal of Sensor Science and Technology
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• v.31 no.2
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• pp.115-119
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• 2022

A readout circuit for a mercury-cadmium-telluride (MCT)-amplified mid-wave infrared (IR) photodetector was realized and applied to noncontact chemical agent detectors based on a quantum cascade laser (QCL). The QCL emitted 250 times for each wavelength in 0.2-㎛ steps from 8 to 12 ㎛ with a frequency of 100 kHz and duty ratio of 10%. Because of the nonconstant QCL emission power during on-duty, averaging the photodetector signals is essential. Averaging can be performed in digital back-end processing through a high-speed analog-to-digital converter (ADC) or in analog front-end processing through an integrator circuit. In addition, it should be considered that the 250 IR data points should be completely transferred to a PC during each wavelength tuning period of the QCL. To average and minimize the IR data, we designed a readout circuit using the analog front-end processing method. The proposed readout circuit consisted of a switched-capacitor integrator, voltage level shifter, relatively low-speed analog-to-digital converter, and micro-control unit. We confirmed that the MCT photodetector signal according to the QCL source can be accurately read and transferred to the PC without omissions.

• 연구논문집
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• s.30
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• pp.43-56
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• 2000

N-IR spectroscopy technology is very useful. And, the technology has wide application range. In the range, we know that single beam type silica analyzer has some handicap. So we were studied Splitted beam type silica analyzer. This dissertation have been discuss about system structure, system fundamentals and performance test. At the test, we were study in the spectral interference of NH3. We know that existing system had some problem. It is structural frailties of single beam type. Therefore we were study for Splitted beam type structure. And we obtain a good result. We have $\pm$5% accuracy and 0.5 ppb level measuring range. But, we have a question. It is ppt level measuring technology by the laser beam spectroscopy.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.1-6
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• 2008

We report the simple detection method of the small hydrocarbons, methane and ethane, by continuous-wave cavity ring-down spectroscopy near 1.67 ${\mu}m$ using an external cavity diode laser. The absorption lines of methane between 6002.48 $cm^{-1}$ and 6003.37 $cm^{-1}$ and ethane between 5955.65 $cm^{-1}$ and 5956.4 $cm^{-1}$ have been resolved and employed for the gas detection. The largest absorption cross sections were found to be 6.5$\times10^{-20}cm^2$ and 7.4$\times10^{-21}cm^2$ for methane and ethane, respectively, in each spectral range. The minimum detectable absorption limit of our spectrometer was 4.8${\times}10^{-9}cm^{-1}$/$\sqrt{Hz}$, which corresponds to the detection limits of 3 ppb/$\sqrt{Hz}$ and 27 ppb/$\sqrt{Hz}$ for methane and ethane, respectively. The near-IR continuous-wave cavity ring-down spectroscopic detection method of the small hydrocarbons can be applied for medical diagnosis and environmental monitoring as a fast and convenient method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.893-898
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• 2014

A direct pulsed laser process for welding and networking silver nanowires was developed. The welded nanowire network demonstrated modified electrical properties in a transparent substance. In particular, the welding points on the nanowires were investigated to measure the resistance at the connections. The level of networking in nanowires was explored with respect to various laser pulse widths and average power densities. In particular, the influence of laser beam density was investigated in detail. Selective laser treatment can be advantageous in imparting customized local property changes in transparent conducting materials. Various applications of the process are also discussed in this paper.

• The Journal of Korean Physical Therapy
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• v.9 no.1
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• pp.1-18
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• 1997

The purpose of this study is to investigate the effects of the low power Helium Neon-Infra Red(HeNe-IR) laser and the special electromagnetic therapeutic apparatus stimulation, which is usually designated as TDP by using the initial of Tending Diancibo Pu which is the Chinese inscribed with English, on wound healing in rat. The seventy-five Sprague-Dawley adult female and male rats were assigned to the experimental and control groups. Each rat was anesthetized with pentobarbital sodium, and three full-thickness incisions with 12mm length wert made on the back of the half cf the rats and three deep second degree burns were made on the back of the remainder of the rats. From 34 hours after being injured, the rats of the experimental laser group were irradiated with the 157mW electric power HeNe-IR laser for 2 minutes every day and the rats of the experimental TDP group were stimulated with TDP irradiation with the 4km spot distance for 20 minutes every day during the 17 days. The rats were sacrificed and the wound parts of its were incised on the first day, 4th day, 7th day, 10th day and 17th day respectively after the beginning of wound treatment with laser and TDP irradiation. The incised wound parts were processed appropriately for the light microscopic and electron microscopic examination. The length of incised wound was measured with microcaliper before the wound part was incised. There was a significant decrease in the length of the incised wound of the experimental laser and TDP group, compared with that of control group at 4th day, 7th day and 10th day(p<0.01) after surgery. Through the histological examination of the wound site, the more rapid epithelialization and collagen formation in experimental groups were showed, compared with control group. The histological results were analyzed and summarized as the follows; The epidermis begins to be regenerated and the granulation tissue begins to be changed to the mature pattern in the H-E stained incised skin of the laser and TDP treatment group on the 4th day. The epidermis shows the complete regeneration and the granulation tissue in the dermis in mostly to be matured in the laser and TDP treatment group on the 7th day, compared with control group. The chronic inflammatory cells are oberved and the necrosis of the collagen fibers are partially observed in control group on the 10th day. The dermis of the laser and TOP treatment group reveals relatively compactly arranged collgen bundles with the mature collagen fibers on the 10th day. The epidermis and dennis of the laser and TDP group are repaired normally and the hair follicles are well regenerated on the 17th day. The mild edema and the granulation tissue is observed in the dermis of the control groups and the delayed treatment process is observed on the 17th day. The Most of proliferated collagen fibrils are found to be compact and regular in electron micrograph of burn skin of the laser treatment group on the 10th day hut the interstitial eadema and some inflammatory cells are found in the control group. The above results suggest that through the visual and histological examination the epithelized epithelium and the proliferation of the collagen liters in the dermis occur very effectively with the low power laser treatment and the TDP treatment in the incised wound healing and the burn wound healing.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.172-176
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• 1990

A high resolution picosecond absorption kinetic spectrometer utilizing dye emission and a streak camera is presented and compared with other methods of picosecond transient absorption measurements. Typical transient absorption and bleach recovery kinetics measured with this spectrometer are shown. Single wavelength transient absorption or ground state bleach recovery kinetics are determined on the basis of a single laser shot, so that the samples are relatively free frm decomposition by irradiation. Excellent kinetics may be obtained from the near UV to the near IR and are not subject to interference from luminescence of samples. The sensitivity of this spectrometer is very high and it is reasonably easy and convenient to set up and use.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.238-239
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• 2000

The optical fibers are an interesting medium for effective tunable optical frequency conversion in the spectral range of UV, Visible, and near-IR through the nonlinear processes. A number of papers for developing the wideband and flat-gain amplifier for the WDM system applications through the combination of EDFA or thulium-doped fluoride fiber amplifier and Raman amplifier, are reported$^{(1)}$ . Even though a variety of papers related to Raman amplifications are published, the amplification with the feedback of the residual pump is not investigated yet. Accordingly, in this paper, we report the characteristics of forward Raman amplification by the simple and double-pass fiber Raman configuration through the feedback of residual pump beam. (omitted)

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3274-3278
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• 2013

$CF_2Cl{\cdots}Cl$, an elusive photo-isomer of $CF_2Cl_2$, has been observed in matrix IR spectra from the precursors exposed to radiation from laser ablation of transition-metals. Other plausible products, $CFCl_2{\cdots}F$ and $FClC{\cdots}F-Cl$ are not detected due to their considerably higher energies. Parallel to its previously reported analogues, the C-X bonds are considerably stronger than those of the reactant, and particularly the Cl atom that is weakly bound to the residual Cl atom forms an unusually strong carbon-halogen bond. NBO analysis reveals that the C-Cl bond is a true double bond, and the weak $Cl{\cdots}Cl$ bond is largely ionic, $F_2C=Cl^{\delta+}{\cdots}Cl^{\delta-}$. IRC computation reproduces smooth inter-conversion between the reactant and product, and the transition state is energetically close to the product, consistent with its prompt disappearance in the early stage of photolysis.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.20-23
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• 2009

The efficacy improvement issues in a unit discharge cell have been approached from the structural considerations. The tested cell designs include (a) a coplanar type with annular auxiliary electrode buried in barrier ribs, (b) a coplanar type with split auxiliary electrodes also burred in barrier ribs and (c) a coaxial type with a floating electrode stacked on the base electrode. From spatiotemporally resolved optical images of near-IR emission taken by a gated-ICCD camera and relative VUV emission intensity estimated by laser absorption spectroscopy, the differences in the discharge and light emission performances of those three cell types have been compared and discussed.

• Journal of the Korean institute of surface engineering
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• v.46 no.4
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• pp.162-167
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• 2013

Encapsulation is required since organic materials used in OLED devices are fragile to water vapor and oxygen. Laser sealing method is currently used where IR laser is scanned along the glass-frit coated lines. Laser method is, however, not suitable to encapsulating large-sized glass substrate due to the nature of sequential scanning. In this work we propose a new method of encapsulation using Joule heating. Conductive layer is patterned along the sealing lines on which the glass frit is screen printed and sintered. Electric field is then applied to the conductive layer resulting in bonding both the panel glass and the encapsulation glass by melting glass-frit. In order to obtain uniform bonding the temperature of a conductive layer having a shape of closed loop should be uniform. In this work we conducted simulation for heat distribution according to the structure of a conductive layer used as a Joule-heat source. Uniform temperature was obtained with an error of 5% by optimizing the structure of a conductive layer. Based on the results of thermal simulations we concluded that Joule-heating induced encapsulation would be a good candidate for encapsulation method especially for large area glass substrate.