• Korean Journal of Remote Sensing
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• v.27 no.5
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• pp.535-542
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• 2011

We extracted a surface displacement map of Canisteo Peninsula and the surrounding area in West Antarctica by applying 4-pass DInSAR technique to two ERS-1/2 tandem pairs and analyzed the surface displacement of glaciers and sea ice. In the displacement map, glaciers showed fast motion pushing the adjoining land-fast sea ice which has the displacement in the same direction as the glacier. Cosgrove ice shelf showed large displacement pushing the adjoining land-fast sea ice as well. Some sea ice indicated the displacement that is opposite to the land-fast sea ice. This was because the type of the sea ice is drift ice that is affected by ocean current. Therefore, we could confirmed the boundary between land-fast sea ice and drift ice. It was difficult to distinguish ice shelf from ice sheet because they showed similarities both in brightness of the SAR images and in fringe rates of the interferograms. However, a boundary between fast-moving ice shelf and stable ice sheet was easily confirmed in the displacement map after the phase unwrapping process.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.122-125
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• 1994

The magnetic properties of Nd-Fe-B alloys of containing 4 at.% Nd have been studied for the development of new type rare-earth magnets. The amorphous phase of a melt-spun $Nd_{4}Fe_{85.5}B_{10.5}$ alloy is transformed into the phases which have a small amount of $Nd_{2}Fe_{14}B_{1}$ in ${\alpha}-Fe$ matrix by annealing above their crystallization temperature. The addition of Mo, Nb, V or Cu to $Nd_{4}Fe_{85.5}B_{10.5}$ alloy results in the reduction of grain size and the sub¬sequent improvement of the coercivity. The coercivity of $Nd_{4}Fe_{82}B_{10}M_{3}Cu_{1}$(M = Mo, Nb, V) alloys increases in the order of M = V < Nb < Mo and shows the highest value of 2.7 kOe when M = Mo. On the other hand, the rem¬anence of these alloys shows the opposite trend and the rn>st improved value of 1.35 T is observed when M = V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.211-215
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• 2010

Pulsed laser deposition is a very efficient technique for fabricating thin films of complex compounds. In the present work, $Bi_2O_3$-MgO-ZnO-$Nb_2O_5$ (BMZN) pyrochlore thin films were deposited on platinized Si substrates at various temperatures by using pulsed laser deposition technique. These films have been characterized by X-ray diffractometer (XRD), atomic force microscopy (AFM) to investigate their structural, morphological properties. MIM structure was manufactured to analyze di-electrical properties of BMZN thin films. XRD results reveal the thin films deposited at less than $400^{\circ}C$ show only amorphous phase, the crystallized thin films was observed when the thin films were prepared temperature at above $500^{\circ}C$. From AFM, it was known that the thin film grown at $400^{\circ}C$ is the densest. Dielectric constant increased with increasing temperature up to $400^{\circ}C$ at 100 kHz and dramatically decreased at the higher temperature. A aspect of dissipation factor was the exact opposite of dielectric constant. BMZN thin films grown at $400^{\circ}C$ exhibited a high dielectric constant of 60.9, a low dissipation factor of 0.007 at 100 kHz.

• BMB Reports
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• v.42 no.6
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• pp.373-379
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• 2009

5-Hydroxyuridine (5-OHU) is a major lesion of uridine and cytosine produced in RNA by various chemical oxidants. To elucidate its biochemical and biophysical effects on RNA replication, the site-specifically modified oligoribonucleotides containing 5-OHU were synthesized with C5-hydroxy-5'-ODMTr-2'-TBDMS-uridine phosphoramidite using automated solid phase synthesis. The base-pairing properties of nucleotides opposite 5-OHU in 24 mer oligoribonulcleotides with dNTP were studied using three reverse transcriptases (Super-$Script^{TM}II$-, AMV-, MMLV-RT) in cDNA synthesis. Adenine as well as guanine was incorporated preferentially by all reverse transcriptases. In the UV-melting temperature experiment, the results from the relative stabilities of the base pairs were A : 5-OHU > G : 5-OHU > T : 5-OHU $\approx$ C : 5-OHU. Circular Dichroism (CD) studies showed that DNA-RNA containing 5- OHU heteroduplexes exhibit a similar conformation between the A-type RNA and B-type DNA. These results suggest that 5- OHU from oxidative damage was mainly influenced by adenine mismatch.

• BMB Reports
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• v.50 no.9
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• pp.472-477
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• 2017

The transcription repressor Bach2 has been proposed as a regulator of T cell quiescence, but the underlying mechanism is not fully understood. Given the importance of interleukin-2 in T cell activation, we investigated whether Bach2 is a component of the network of factors that regulates interleukin-2 expression. In primary and transformed $CD4^+$ T cells, Bach2 overexpression counteracted T cell receptor/CD28- or PMA/ionomycin-driven induction of interleukin-2 expression, and silencing of Bach2 had the opposite effect. Luciferase and chromatin immunoprecipitation assays revealed that Bach2 binds to multiple Maf-recognition element-like sites on the interleukin-2 proximal promoter in a manner competitive with AP-1, and thereby represses AP-1-driven induction of interleukin-2 transcription. Thus, this study demonstrates that Bach2 is a direct repressor of the interleukin-2 gene in $CD4^+$ T cells during the immediate early phase of AP-driven activation, thereby playing an important role in the maintenance of immune quiescence in the steady state.

• Informatization Policy
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• v.23 no.2
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• pp.35-53
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• 2016

This paper attempts to present critical issues of the information society and an alternative research addressing the challenges of ensuring that ICT is applied in ways that are enabling and responsive to social contexts in which people live their lives. Drawing the question of why insights arising from the mainstream vision are rarely useful in policies, the study highlights some developmental paradigms linked to ICT. It explores how ICT is seen as a means to development, and elaborates on the limitations of how current issues are related to the quality of life. The results indicate that ICT reduces quality of life while economic growth entails the opposite. The research framework here involves some meaningful components of cultural residues: independence, risk-taking, government responsibility by mapping how the level of ICT is distributed in the topology of values around the world. Moving to the next phase, ICT policy design and implementation need to be set up practically in a broad perspective that can be pursued by those concerned with social and technological innovation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.294-301
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• 2000

One of the most important design parameters in a microwave radio transmitting system is to reduce spurious response from the output spectrum of the transmitting system. A Local oscillator (LO) is seldom totally pure and at the least contain some LO harmonic signals. A LO or any oscillator is a transmitter if provided with a suitable radiator, conduction, or leakage path. Where mixer is employed in the output of the LO mixer generated spurs can be increased by RF amplifier. To reduce LO leakage, notch filter or band pass filter has been conventionally used. In this paper, the leakage reduction(LR) signal, which has the same magnitude and the opposite phase with respect to LO leakage signal, is added to the output of mixer of the wireless LAN system. The LO leakage is reduced by 30 dB more than the conventional methods do. The proposed method is potentially suitable for low-cost, reliable, and simple application of monolithic microwave integrated circuits (MMICs)

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.514-522
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• 2000

In this thesis, a two-dimensional active phased array antenna without phase shifter is studied for two-dimensional beam scanning. A designed two-dimensional oscillator-type active array antenna, radiation elements and the oscillator circuits were combined with via-hole and coupled by slot on the opposite ground plane. The operating characteristics are analyzed and experimentally demonstrated , The two-dimensional $4\times4$ elements were designed for the proper coupling strengths and coupling phases by adjusting the width, length and offset position of slot-lines. The fabricated active phased array antenna shows the beam shift characteristics capable of scanning from $-17^{\circ}$ to $18^{\circ}$ with respect to broadside in one dimension, from $-5^{\circ}$ to $10^{\circ}$ in two dimension. The experimental results show that it is possible to use the oscillator-type active phased array antenna as a two-dimensional planar array antenna.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.15-26
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• 2005

An experimental investigation of the gas-phase photooxidation of toluene-NO$_{x}$-air mixtures at sub-ppm concentrations has been carried out in a 6.9 m3, indoor smog chamber irradiated by blacklights. Measured parameters in the toluene-NO$_{x}$ experiments included $O_3$, NO, NO$_2$, NO$_{x}$, CO, SO$_2$ toluene, and air temperature. The initial toluene concentration ranged from 225 ppb to 991 ppb and the initial concentration ratio of toluene/NO$_{x}$ in ppbC/ppb was in the range of 5～20. It was found that the variation of gaseous species with irradiation time caused by the photooxidation of toluene-NO$_{x}$-air mixtures depended on the initial toluene concentration for similar concentration ratio of toluene/NO$_{x}$. The dependency of initial toluene concentration on the photooxidation of toluene-NO$_{x}$-air mixtures for toluene/NO$_{x}$=5～6 seemed to be opposite to that for toluene/NO$_{x}$=10～11. The arriving time at maximum ozone concentration depended on both initial toluene concentration and initial concentration ratio of toluene/NO$_{x}$. However, the maximum concentration of ozone formed by photooxidation depended only on the initial toluene concentration.luene concentration.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.27-38
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• 2005

An experimental investigation of the gas-phase photooxidation of toluene-NO$_{x}$-air mixtures at sub-ppm concentrations has been carried out in a 6.9 ㎥, indoor smog chamber irradiated by blacklights. Measured parameters in the toluene-NO$_{x}$ experiments included aerosol, $O_3$, NO, NO$_2$, NO$_{x}$ CO, SO$_2$ toluene, and air temperature. The initial toluene concentration ranged from 225 ppb to 991 ppb and the initial concentration ratio of toluene/NO$_{x}$ in ppbC/ppb was in the range of 5～20. It was found that the variation of aerosol number concentration with irradiation time caused by the photooxidation of toluene-NO$_{x}$-air mixtures depended on the initial toluene concentration for similar concentration ratio of toluene/NO$_{x}$. The dependency of initial toluene concentration on the photooxidation of toluene-NO$_{x}$-air mixtures for toluene/NO$_{x}$= 5～6 seemed to be opposite to that for toluene/NO$_{x}$=10～11. The maximum number concentration of aerosols formed by photooxidation and the aerosol yield depended on both initial toluene concentration and initial concentration ratio of toluene/NO$_{x}$. In this study, the aerosol yield, defined as aerosol formed per unit toluene consumed, was found to be 0.01～0.16.und to be 0.01～0.16.