• Journal of The Korean Astronomical Society
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• v.29 no.2
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• pp.107-117
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• 1996

We have studied the star forming activities and dust properties of Lynds 1251, a dark cloud located at relatively high galactic latitude. Eleven IRAS point sources identified toward Lynds 1251 are discussed. Estimate of stellar masses, and far-infrared lumnosities of the young stars associated with two prominent IRAS point sources imply that these are T-Tauri stars with masses smaller than $0.3 M_\bigodot$. The low dust temperature of 27 K and low ratio of FIR emission to hydrogen column density are probably due to the lack of internal heating sources. Presumably two low mass young stars do not have enough energy to heat up the dust and gas associated. The dust heating is dominated by the interstellar heating source, and the weaker interstellar radiation field can explain the exceptionally low dust temperatures found in Lynds 1251. The estimated dust mass of Lynds 1251 is just $\~1M_\bigodot$, or about 1/1000 of gas mass, which implies that there must be a substantial amount of colder dust. The infrared flux at $100{\mu}m$ is matching well with $^{13}CO$ peak temperature, while the $^{12}CO$ integrated intensity is matching with the boundary of dust emission. Overall, the dust properties of Lynds 1251 is similar to those of normal dark clouds even though it does have star forming activities.

• Journal of the Korean Ceramic Society
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• v.32 no.7
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• pp.769-776
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• 1995

Infrared radiators of a cordierite system [cordierite (2MgO.2Al2O3.5SiO2)＋30wt% clay＋X wt% MnO2 (X=0, 0.1, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5)] were manufactured by a slurry casting method. Thermal and physical properties of these infrared radiators were studied by the measurement of spectra emissivity, thermal expansion coefficient and apparent density, SEM and EPMA analyses were also carried out. The thermal expansion coefficient and apparent density were decreased with increasing amouonts of MnO2 additives. On the other hand, the spectral emissivity was increased in the wavelength below 4.5${\mu}{\textrm}{m}$. Also, infrared radiators of the cordierite system, of which the spectral emisivity was 0.8, could be attainable in the wavelength above 4.5${\mu}{\textrm}{m}$. The infrared radiator of the cordierite system with 2.0wt% MnO2, of which the spectral emissivity was approximately 1.0, could be attainable in the wavelength between 4.5${\mu}{\textrm}{m}$ and 8${\mu}{\textrm}{m}$. The spectral emissivity of the specimen containing 2.0wt% MnO2 was higher than others in the wavelength between 8${\mu}{\textrm}{m}$ and 14${\mu}{\textrm}{m}$.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1622-1622
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• 2001

The purpose of this research was to develop a the reflection technique with near infrared (NIR) radiation for estimating physico-chemical properties in compost. The composts (cattle, pig, chicken and waste composts) were air dried and then ground to pass through a 0.5 or 2mm sieve for the physico-chemical properties and spectroscopic determinations. The physico-chemical properties of compost were shown high values ; moisture(30-60%), T-N(0.8-2.9%), organic matter(29-89%), pH(5.89-9.60) K$_2$O(0.27-5.66%), P2O$\sub$5/(0.07-2.62%), CaO(0.03-4.80%), MgO(0.09-1.56%), NaCl(0.01-1.13%), EC(1.41-13.76dS/m). Generally, we should select a simple calibration and prediction method for determining physico-chemical properties in compost under similar accuracy and precision of prediction. It should be remembered that the NIRS approach will never replace the traditional methods. However, NIRS technique may be an effective method for rapid and nondestructive measurements of a large number of compost samples. Near infrared reflectance spectra of composts was obtained by Infra Alyzer 500 scanning spectrophotometer at 2-nm intervals from 1100 to 2500nm. Multiple linear regression(MLR) or partial least square regression (PLSR) was used to evaluate a NIRS method for the rapid and nondestructive determination of physico-chemical properties and humic acid contents in composts. The standard error of prediction(SEP) for finely sized sample(<0.5mm) and coarsely sized sample(<2mm) did not show much difference. The NIR instrument of filter type showed the same accuracy of the monochromator scanning type to estimate the compost properties. The results summarized that NIR spectroscopy can be used as a routine testing method to determine quantitatively the OM, moisture, T-N, color, pH, cation content in the compost samples nondestructively.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.11a
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• pp.115-116
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• 2009

In this study, near-infrared absorbing dyes, namely, new rigidified heptamethine cyanine dyes were synthesized and investigated their properties. The cyanine dyes have been synthesized by a condensation reaction between a quanternary salt containing as activated methyl group and an unsaturated bisaldehyde or its equivalent. We were investigated the synthesis of new rigidified heptamethine cyanine and related the compounds with near infrared absorption. The full spectroscopic characterization of all cyanine were described. Absorption properties in the near-infrared region may cause these dyes to the potential used in bio-probe, optical recording media materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1727-1732
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• 2004

A nickel layer was deposited onto the PZT thin films, serving both as a selective radiation absorption layer and as a top electrode. The absorption properties of such nickel coated multi-layered infrared detectors were studied in the visible and infrared wavelength ranges. The optimal thickness of the nickel layer on our substrate was 10nm. The maximum absorption coefficient of the deposited 10nm thick nickel layer was 0.7 at a 632nm wavelength. However, a striking asymmetric polarization hysteresis loop was observed in these PZT thin films with nickel as the top electrode. This asymmetric polarization was attributed to the difference between the dynamic pyroelectric responses in these Ni/PZT/Pt films poled either positively or negatively before the measurement. A positively poled film showed a 40% higher voltage response than a negatively poled detector.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.133-137
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• 1994

Infrared radiator of Cordierite system were manufactured using Cordierite(2Mgo$.$2Al$_2$O$_3$$.$5SiO$_2$) and Clay 30wt% as main materials and addition of MnO$_2$ from 0. 1 to 2 5wt% of Dry pressing and slip casting The effects of MnO$_2$ additives on the thermal properties of infrared radiator of Cordierite system. The more the thermal expansion could be lowered the more the amount (wt%) of additives MnO$_2$is increased in the below 4.5$\mu\textrm{m}$. The high efficiency Infrared radiator of Cordierite system using dry pressing method when the amount of additives MnO$_2$is 2.0 wt%

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.57-59
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• 2005

In our study, the automatic tracking algorithm of a human face is proposed by utilizing the thermal properties and 2nd momented geometrical feature of an infrared image. First, the facial candidates are estimated by restricting the certain range of thermal values, and the spurious blobs cleaning algorithm is applied to track the refined facial region in an infrared image.

• Polymer(Korea)
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• v.24 no.1
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• pp.65-71
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• 2000

The latent properties and cure kinetics of an acid anhydride-cured epoxy resin have been investigated by a near-infrared (NIR) reflection spectroscopy. The assignments of the latent properties and cure behaviors were performed by the measurements of the NIR reflectance for epoxide and hydroxyl groups at different temperatures. A comprehensive analysis of the origin, location, and shifts during reaction of all major NIR absorption peaks in the spectral range from 4000 to 7100 $cm^{-1}$ / was provided. The extent of reaction was determined from NIR absorption band at the 4530 $cm^{-1}$ / depending on epoxide concentration and cure temperature.

• Journal of Sensor Science and Technology
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• v.28 no.2
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• pp.101-105
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• 2019

ZnS substrates with excellent transmittance in the mid-infrared region ($3-5{\mu}m$) were prepared using hot pressing instead of conventional chemical vapor deposition (CVD). Diamond-like carbon(DLC) was coated on either one or both sides of the ZnS substrates to improve their mechanical properties and transmittance. More specifically DLC was coated using CVD with an Ar and $C_2H_2$ mixed gas, and Ge was used as the bonding layer. During CVD, the bias voltage was fixed to 500 V and analyzed by Fourier transform infrared spectroscopy (FT-IR), nanoindenter, scanning electron microscope and energy dispersive spectrometry. Results of hardness analysis using the nanoindenter, showed that DLC coating increased from 5.9 to 17.7 GPa after deposition. The FT-IR spectroscopy results showed that, in the mid-infrared region ($3-5{\mu}m$), the average transmittance of the samples with DLC coating on one and both sides increased by approximately 6% and approximately 11.2% respectively. In conclusion, the DLC coating improved the durability and transmittance of the ZnS substrates.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.245-249
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• 2017

We selected 47 DOGs at z ~ 1.5 using optical R (or r'), AKARI $18{\mu}m$, and $24{\mu}m$ color in the AKARI North Ecliptic Pole (NEP) Deep survey field. Using the colors among 3, 4, 7, and 9µm, we classified them into 3 groups; bump DOGs (23 sources), power-law DOGs (16 sources), and unknown DOGs (8 sources). We built spectral energy distributions (SEDs) with optical to far-infrared photometric data and investigated their properties using SED fitting method. We found that AGN activity such as a AGN contribution to the infrared luminosity and a Chandra detection rate for bump and power-law DOGs are significantly different, while stellar component properties like a stellar mass and a star-formation rate are similar to each other. A specific star-formation rate range of power-law DOGs is slightly higher than that of bump DOGs with wide overlap. Herschel/PACS detection rates are almost the same between bump and power-law DOGs. On the other hand SPIRE detection rates show large differences between bump and power-law DOGs. These results might be explained by differences in dust temperatures. Both groups of DOGs host hot and/or warm dust (~ 50 Kelvin), and many bump DOGs contain cooler dust (${\leq}30$ Kelvin).