• Journal of the Optical Society of Korea
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• v.13 no.2
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• pp.223-226
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• 2009

A Magneto-Optical Trap (MOT) for $^{87}Rb$ atoms near the surface of a dielectric coated mirror at the top of a small $20{\times}25{\times}40\;mm^3$ cell has been observed. Two beams of $3.3\;mW/cm^2$ were used for optical cooling and an anti-Helmholtz magnetic field with a spatial gradient of 9.1 G/cm was used for magnetic trapping. The thickness of the mirror coated on a cover glass was less than $100{\mu}m$. The mirror covered the top of a cell and the atom-chip was located outside the vacuum in order to exploit the long life time of the mirror and easy operation of the chip. The trapping position was found 5 mm beneath the mirror surface. The number of trapped atoms was roughly $3{\times}10^7$ atoms and the temperature was approximately a few tens mK. In this paper, we describe the construction of the mirror-MOT in detail.

• Korean Journal of Materials Research
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• v.30 no.8
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• pp.413-420
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• 2020

Lu₃Al_5-xGa_xO₁₂:Ce³⁺,Cr³⁺ powders are prepared using a solid-state reaction method. To determine the crystal structure, Rietveld refinement is performed. The results indicate that Ga³⁺ ions preferentially occupied tetrahedral rather than octahedral sites. The lattice constant linearly increases, obeying Vegard's law, despite the strong preference of Ga³⁺ for the tetrahedral sites. Increasing x led to a blue-shift of the Ce³⁺ emission band in the green region and a change in the emission intensity. Persistent luminescence is observed from the powders prepared with x = 2-3, occurring through a trapping and detrapping process between Ce³⁺ and Cr³⁺ ions. The longest persistent luminescence is achieved for x = 2; its lifetime is at least 30 min. The findings are explained using crystal structure refinement, crystal field splitting, optical band gap, and electron trapping mechanism.

• The KIPS Transactions:PartA
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• v.15A no.4
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• pp.211-216
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• 2008

In this paper we fabricated and measured the $0.26{\mu}m$ NMOSFET with wet gate oxide and nitride oxide gate to compare that the charateristics of hot carrier effect, charge to breakdown, transistor Id_Vg curve, charge trapping, and SILC(Stress Induced Leakage Current) using the HP4145 device tester. As a result we find that the characteristics of nitride oxide gate device better than wet gate oxide device, especially hot carrier lifetime(nitride oxide gate device satisfied 30 years, but the lifetime of wet gate oxide was only 0.1 year), variation of Vg, charge to breakdown, electric field simulation and charge trapping etc.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.415-418
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• 2005

To understand effects of carbon nanotubes (CNTs) dispersed in nematic liquid crystal (NLC) on electro-optic characteristic and orientation of the LC, we CNT-doped homogeneously-aligned NLC cells driven by in-plane field have been fabricated. The CNTs were aligned with a LC director from the initial state to below critical ac field, whereas the CNTs disturbed the LC director field above critical ac field. We observed motional textures in the form of vertical stripes in the local area between electrodes, which were associated with a deformation of the LC director orientation. This indicates that CNTs start vibrating three dimensionally with translational motion. Further, the hysterisis studies of voltage-dependent transmittance under dc electric field show that the amount of residual dc, which is related to image sticking problem in liquid crystal displays, is greatly reduced due to ion trapping by CNTS while keeping operating voltage and response time about the same compared to the un-doped LC cell.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.2
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• pp.69-89
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• 2020

Scientific trust and quantification of traditional species investigation and results that have been used in ecology for decades has always been a problem and concern for ecologists. Global ecologists have proposed DNA-based species investigation studies to find answers to problems. In this study, we reviewed the global trend of research on environmental DNA(eDNA), which is a method for monitoring species by detecting DNA of organisms naturally mixed in environmental samples such as water, soil, and feces. The first eDNA research confirmed the possibility of species investigation at the molecular level, and commercialization of NGS(Next Generation Sequencing) and DNA metabarcoding elicits efficient and quantitative species investigation results, and eDNA research is increasing in the filed of ecology. In this study, mammals and birds were detected using MiMammal universal primers from 23 samples(3 natural reserves; 20 water bowls) out of 4 patches to verify eDNA for urban ecosystems in Suwon, and eDNA was verified by performing camera trapping and field survey. Most terrestrial species were detected through eDNA, and particularly, mice(Mus musculus), and Vinous-throated Parrotbill (Sinosuthora webbiana) were identified only with eDNA, It has been confirmed to be highly effective by investigating techniques for small and internal species. However, due to the lack of resolution of the primer, weasels(Mustela sibirica) and squirrels(Melanochromis auratus) were not detected, and it was confirmed that the traditional investigation method was effective only for a few species, such as Mogera robusta(Mogera robusta). Therefore, it is judged that the effects of species investigation can be maximized only when eDNA is combined with traditional field survey and Camera trapping to complement each other.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.182-187
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• 2011

In this paper, PBTI characteristics of NMOSFETs with La incorporated HfSiON and HfON are compared in detail. The charge trapping model shows that threshold voltage shift (${\Delta}V_{\mathrm{T}}$) of NMOSFETs with HfLaON is greater than that of HfLaSiON. PBTI lifetime of HfLaSiON is also greater than that of HfLaON by about 2~3 orders of magnitude. Therefore, high charge trapping rate of HfLaON can be explained by higher trap density than HfLaSiON. The different de-trapping behavior under recovery stress can be explained by the stable energy for U-trap model, which is related to trap energy level at zero electric field in high-k dielectric. The trap energy level of two devices at zero electric field, which is extracted using Frenkel-poole emission model, is 1,658 eV for HfLaSiON and 1,730 eV for HfLaON, respectively. Moreover, the optical phonon energy of HfLaON extracted from the thermally activated gate current is greater than that of HfLaSiON.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1549-1551
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• 2004

The Electromagnetic properties in BiPbSrCaCuO superconductor was studied. In the measurement of current-voltage characteristics, a voltage across the superconducting sample was observed on applying an external magnetic field. The voltage continues to appear the removal of the magnetic field. The appearance of the voltage is ascribed to the trapping of magnetic flux. Depanding on the direction of applied magnetic flux less than 2.5${\times}$10-5 T, the voltage in the magnetized sample increases or decreases. It is considered that mechanism of voltage occurrence can be explained by applying filament model.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.8
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• pp.808-815
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• 1991

The behavior of space charge in PE/ionomer blends has been investigated using the thermally stimulated current (TSC) technique. In the blends, at least two TSC peaks over the temperature range from -50 to 100\ulcorner are observed, one at -5 ~ 10\ulcorner (a peak) and the others at above 60\ulcorner (a peak). The a peak is assigned as the orientation of dipoles from the ionomer component. Two a peaks seem to be related to the charge trapping at sites related to the crystalline phases. One a peak is associated with the ionic interfaces and the other with the ethylene chains without the ionic interfaces. The amount of charges stored in PE/Surlyn 1652 blends increases as the poling field increases over the field range of +8 ~ +30 kV/mm, whereas that in PE/Surlyn 1601 blends increases slightly at low poling fields and then decreases at high poling fields above +10 kV/mm. Exact reasons for such a dirrerence are not known at this point.

• Journal of Powder Materials
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• v.13 no.6 s.59
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• pp.439-444
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• 2006

An electromagnetic properties in BiSrCaCuO superconductor were studied. In the measurement of current-voltage properties, the voltage was measured when applying an external magnetic field. The voltage continues to appear after the removal of the magnetic field. This phenomenon was considered as a nonvolatile magnetic effect. The voltage increased with the applied magnetic flux, but it became constant at about $10^{-2}$T. The appearance of the voltage was ascribed to the trapping of magnetic flux.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.10
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• pp.453-456
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• 2005

We have fabricated superconducting ceramics by chemical process. A high Tc superconducting with a nominal composition of YBaCuO was prepared by the pyrolysis method. The electromagnetic properties in YBaCuO superconductor was studied. In the measurement of current-voltage characteristics, a voltage across the superconducting sample was observed on applying an external magnetic field. The voltage increases with increase in applied magnetic flux, but it becomes constant at about 10$^{-2}$T. The voltage continues to appear the removal of the magnetic field. The appearance of the voltage is ascribed to the trapping of magnetic flux. Depending on the direction of applied magnetic flux less than 2.5$\times$10$^{-5}$ T, the voltage in the magnetized sample increases or decreases.