• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.76-82
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• 1998

Increase of greenhouse gas due to $CO_2$ and CH$_4$ gases would cause the global warming in the atmosphere. According to the global circulation model, it is pointed out in the Okhotsk Sea that the large increase of atmospheric temperature might be occurredin this region by global warming due to the doubling of greenhouse effectgases. Therefore, it is very important to monitor the sea ice extents in the Okhotsk Sea. To improve the sea ice extents and concentration with more highly accuracy, the field experiments have begun to comparewith Airborne Microwave Radiometer (AMR) and video images installed on the aircraft (Beach-200). The sea ice concentration is generally proportional to the brightness temperature and accurate retrieval of sea ice concentration from the brightness temperature is important because of the sensitivity of multi-channel data with the amount of open water in the sea ice pack. During the field experiments of airborned AMR the multi-frequency data suggest that the sea ice concentration is slightly dependending on the sea ice types since the brightness temperature is different between the thin and small piece of sea ice floes, and a large ice flow with different surface signatures. On the basis of classification of two sea ice types, it is cleary distinguished between the thin ice and the large ice floe in the scatter plot of 36.5 and 89.0GHz, but it does not become to make clear of the scatter plot of 18.7 and 36.5GHz Two algorithms that have been used for deriving sea ice concentrations from airbomed multi-channel data are compared. One is the NASA Team Algorithm and the other is the Bootstrap Algorithm. Intrercomparison on both algorithms with the airborned data and sea ice concentration derived from video images bas shown that the Bootstrap Algorithm is more consistent with the binary maps of video images.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.126-133
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• 1992

This study deals with the crystal growth and the optical characteristics of CdS thin films activatedby silver. CdS:Ag thin films were deposited by using an electron beam evaporation(EBE) technique in vacuumof 1.5X 10-'torr, voltage of 4 kV, current of 2.5 mA and substrate temperature of 250$^{\circ}$C CdS:Ag photoconductivefilms prepared by EBE method show high photoconductivity after annealing at about 550"c for 0.5 h in air andAr gas.The grain size of CdS:Ag thin films annealed in Ar atmosphere (1 atm) was grown over 1 ym and the thicknessof the films is 4-5 pm. The analysis of X-ray diffraction patterns shows that the crystal structures are hexagonal.The diffraction line by (00.2) plane can only be observed, indicating that c-axis of hexagonal grows preferentiallyperpendicular to the substrate. The profiles of photoluminescence spectra of CdS:Ag films show Gaussian typecurves at room temperature, the maximum peak spectral sensitivity of CdS:Ag is located at the wavelength of520 nm.We annealed CdS:Ag thin films in air and Ar vapor in order to make the CdS photoconductors having theintensive photocurrent, the broad distribution of the photocurrent spectrum and the large value of the ratioof the photocurrent (pc) to the dark current(dc). We found that CdS:Ag thin films annealed in air atmospherewas the best one.air atmosphere was the best one.

• Analytical Science and Technology
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• v.13 no.6
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• pp.736-742
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• 2000

The purpose of this study was to determine the homocysteine (Hey), methionine (Met) and cysteine (Cys) using solid phase micro-extraction (SPME)/gas chromatography (GC)-mass spectrometry (MS) in human plasma and to correlate between the plasma concentration of homocysteine with coronary artery disease. The homocysteine, methionine and cysteine in blood can be used as biomarkers for the risk assessment of vascular disease. The plasma homocysteine level for the coronary artery disease patients was higher than general patients. The concentration ranges of the Hcy, Met and Cys for coronary artery disease patients were $18.47-33.38{\mu}mol/L$, $30.16-55.72{\mu}mol/L$ and $183.16-387.32{\mu}mol/L$, respectively. This method showed good sensitivity and convenience.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.112.2-112.2
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• 2011

We carry out a systematic study of HI shells and supershells in the first Galactic quadrant (l = $32^{\circ}$ to $77^{\circ}$, b = $-10^{\circ}$ to $10^{\circ}$) using the "Inner-Galaxy Arecibo L-band Feed Array (I-GALFA)" HI 21-cm survey data. The high-resolution (3.'4) and high sensitivity (0.2 K) of the survey provide us an opportunity to exploit the true nature of the sources detected in previous low-resolution studies and also to detect faint and/or small shells that were not detectable before. Our work is composed of three parts: (1) confirm the objects in the low-resolution (about 30') catalog of Heiles (1979), (2) search for fast-expanding HI shells associated with Galactic supernova remnants (SNRs), and (3) search for new shell structures. Among the 21 Heiles' supershells in the I-GALFA survey area, we confirm fourteen. The high resolution data reveal their complex morphology, and provide direct evidence for expansion in some sources. Among the 39 Galactic SNRs in the survey area, we find five with associated fast expanding HI shells, which is consistent with previous results. A remarkable result from the SNR study is the detection of HI gas at very high negative velocities in the SNR W44 that should be from the approaching part of the HI expanding shell. This is the first time to detect both the approaching and receding sides of an expanding shell in HI 21-cm emission line in SNRs. We have found 33 new shell candidates of angular sizes ranging from 0.5 to 6.5 degrees, half of which appear to be expanding. We summarize these results and discuss some individual interesting objects in detail.

• Macromolecular Research
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• v.17 no.7
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• pp.528-532
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• 2009

The size and shape of free volume (FV) holes available in membrane materials control the rate of gas diffusion and its permeability. Based on this principle, a segmented, thermo-sensitive polyurethane (TSPU) membrane with functional gate, i.e., the ability to sense and respond to external thermo-stimuli, was synthesized. This smart membrane exhibited close-open characteristics to the size of the FV hole and water vapor permeation and thus can be used as smart food packaging materials. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), positron annihilation lifetimes (PAL) and water vapor permeability (WVP) were used to evaluate how the morphological structure of TSPU and the temperature influence the FV holes size. In DSC and DMA studies, TSPU with a crystalline transition reversible phase showed an obvious phase-separated structure and a phase transition temperature at $53^{\circ}C$ (defined as the switch temperature and used as a functional gate). Moreover, the switch temperature ($T_s$) and the thermal-sensitivity of TSPU remained available after two or three thermal cyclic processes. The PAL study indicated that the FV hole size of TSPU is closely related to the $T_s$. When the temperature varied cyclically from $T_s-10{\circ}C$ to $T_s+10^{\circ}C$, the average radius (R) of the FV holes of the TSPU membrane also shifted cyclically from 0.23 to 0.467 nm, exhibiting an "open-close" feature. As a result, the WVP of the TSPU membrane also shifted cyclically from 4.30 to $8.58\;kg/m^2{\cdot}d$, which produced an "increase-decrease" response to the thermo-stimuli. This phase transition accompanying significant changes in the FV hole size and WVP can be used to develop "smart materials" with functional gates and controllable water vapor permeation, which support the possible applications of TSPU for food packaging.

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.389-394
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• 2007

The characteristics of the single mode fiber hydrogen sensor have been investigated theoretically and experimentally. Palladium is adopted as a material for the transducer and a thin Ni film is used for the adhesion between the fiber end and the Pd film. It is shown that sensitivity and response time strongly depend on the thickness of Pd film. The single mode fiber sensor coated with 5 nm thick Ni adhesion layer and 10 nm thick Pd transducer layer showed 0.6 dB change of reflectivity and $3{\sim}5$ sec of response time as it absorbed 4% hydrogen gas.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.173-178
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• 1998

$MgB_4O_7$: Tb, Tm, Dy, La, Ho and Nd phosphors have been prepared by sintering around $580^{\circ}C$ for 2 hours followed by flowing Ar gas. Activation energy and kinetic order of main peak of glow curve were studied by two methods peak shape method and initial rise method. By these methods, the estimated activation energies were $0.76\pm0.02eV$(Tb doped), $0.94\pm0.03eV$(Tm doped), $0.72\pm0.02eV$(Dy doped), respectively. The TL phosphors prepared in this work may be utilized to radiation sensor elements becaue of their high sensitivity to low energy X-ray.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.573-580
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• 2000

MPT, which has been developed recently, is very tolerant to aqueous samples. Several types of MPT have been investigated and is found that the double concentric tube could sustain a stable plasma at a low plasma gas flow rate. However, the tip of torch is easily ruined. Triple concentric torch has shown the best stability and the plasma shape, much like that of ICP, especially when the central channel is quartz. The plasma is exposed and mixed with air as is suggested from the background spectrum, which leads to quenching of He MPT. Sensitivity of helium MPT equipped with a membrane desolvator has shown 10 times lower than that of Argon MPT for most of elements except for the ones with relatively high excitation energy. He MPT requires small plasma flow rate (about 1.6 L/min), stable and simple to use. Excitational temperature and electron number density measured are 4950 K and 3.28 ${\times}$ $10^{14}cm^{-3}$, respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.31-38
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• 2016

Most of propellants that is used widely in the world release toxic gases such as methane gas and carbon dioxide during combustion which are noxious to the environment. This study established a synthetic process of a high nitrogen containing derivative of triazole, 4,5-bis(azidomethyl)-methyl-1,2,3-triazole (DAMTR), which can be applied as energetic plasticizer to environmental concerns. Also, the compound was characterized by NMR, IR spectroscopy, and physical properties such as glass transition temperature, melting point, decomposition temperature, density, impact sensitivity, viscosity and volatility were measured. In addition, the heats of formation (${\Delta}H_f$) and detonation properties (pressure and velocity) of DAMTR were calculated using Gaussian 09 and EXPLO5 programs.

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.252-256
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• 1995

A study was carried out for the development of direct determination of antimony in high purity copper metal without preseparation. The large excess of copper seemed to be performed as the matrix modifier to enhance the absorbance of antimony in copper metal. Sensitivity enhancement of Sb was obtained at the condition of the ashing temperature of $600^{\circ}C(20s){\sim}700^{\circ}C(10s)$ rather than $1000^{\circ}C(20s){\sim}1100^{\circ}C(10s)$, and the atomization temperature of $2200^{\circ}C.$ The operating pressure of argon gas was readjusted to the optimum condition at 2.0 kg/$cm^2.$ The linearity of the Sb calibration graph could be obtained in the range of 20 ppb up to 200 ppb Sb in existence of 5,000 ppm Cu with the coefficient of variation of about 5%.