• Communications of the Korean Mathematical Society
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• v.38 no.1
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• pp.1-9
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• 2023

An le-module M over a commutative ring R is a complete lattice ordered additive monoid (M, ⩽, +) having the greatest element e together with a module like action of R. This article characterizes the le-modules _RM such that the pseudo-prime spectrum X_M endowed with the Zariski topology is a Noetherian topological space. If the ring R is Noetherian and the pseudo-prime radical of every submodule elements of _RM coincides with its Zariski radical, then X_M is a Noetherian topological space. Also we prove that if R is Noetherian and for every submodule element n of M there is an ideal I of R such that V (n) = V (Ie), then the topological space X_M is spectral.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.784-789
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• 1998

In this work, the optical properties of freestanding GaN single crystalline substrate grown by hydride vapor phase epitaxy(HVPE) were investigated. The low temperature PL spectrum in freestanding GaN consists of free and bound exciton emissions, and a deep DAP recombination around at 1.8eV. The optically-pumped stimulated emission in freestanding GaN substrate was observed at room temperature. At the maximum power density of 2MW/$\textrm{cm}^2$, the peak energy and FEHM of stimulated emission were 3.318 eV and 8meV, respectively. The excitation power dependence on the integrated emission intensity indicates the threshold pumping power density of 0.4 MW/$\textrm{cm}^2$.

• Corrosion Science and Technology
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• v.2 no.5
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• pp.212-218
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• 2003

Electronic properties of passive films formed on Ti at film formation potentials $(E_f)V_{SCE}$ in pH 8.5 buffer solution and in an artificial seawater were examined through the photocurrent measurement and Mott-Schottky analysis. The passive films formed on Ti in pH 8.5 buffer solution exhibited a n-type semiconductor with a band gap energys $(E_g);E_g^{n=2}=3.4$ eV for nondirect electron transition, and $E_g^{n=0.5}=3.7$ eV for direct electron transition. These band gap values were almost same as those for the passive films formed in artificial seawater, indicating that chloride ion ($Cl^-$ in solution did not affect the electronic structure of the passive film on Ti. $E_g$ for passive films formed on Ti were found to be greater than those ($E_g^{n=0.5}=3.1$ eV, $E_g^{n=2}=3.4$) for a thermal oxide film formed on Ti in air at $400^{\circ}C$. The disorder energy of passive film, determined from the absorption tail of photocurrent spectrum, was much greater than that for the thermal oxide film farmed on Ti in air at $400^{\circ}C$. The greater $E_g$ and the higher disorder energy for the passive film compared with those for the thermal oxide fIlm suggest that the passive film on Ti exhibited more disorded structure than the thermal oxide film. The donor density (about $2.4{\times}10^{20}cm^{-3}$) for the passive film formed in artificial seawater was greater than that (about $20{\times}10^{20}cm^{-3}$) formed in pH 8.5 buffer solution, indicating that $Cl^-$ increased the donor density for the passive film on Ti.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.652-656
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• 2004

A new luminescent polymer, poly{1,4-phenylene-1,2-ethenediyl-2'-[2"-(4'"-octyloxyphenyl)-(5"-yl)-1",3",4"-oxadiazole]-1,4-phenylene-1,2-ethenediyl-2,5-bis-dodecyloxy-1,4-phenylene-1,2-ethenediyl} (Oxd-PPV), was synthesized by the Heck coupling reaction. Electron withdrawing pendant, conjugated 1,3,4-oxadiazole (Oxd), is on the vinylene unit. The band gap of the polymer figured out from the UV-visible spectrum was 2.23 eV and the polymer film shows bright yellow emission maximum at 552 nm. The electroluminescence (EL) maximum of double layer structured device (ITO/PEDOT:PSS/Oxd-PPV/Al) appeared at 553 nm. Relative PL quantum yield of Oxd-PPV film is 3.6 times higher than that of MEH-PPV film. The HOMO and LUMO energy levels of Oxd-PPV figured out from the cyclic voltammogram and the UV-visible spectrum are -5.32 and -3.09 eV, respectively, so that more balanced hole and electron injection efficiency can be expected compared to MEH-PPV. A double layer EL of Oxd-PPV has an maximum efficiency of 0.15 cd/A and maximum brightness of 464 cd/$m^2$.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.1-6
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• 2005

White light emission is very important for applying electroluminescent device to full display, backlight and illumination light source. In this letter, Multilayer molecular organic white-light-emitting device using thin nim of blue material nitro-DPVT with fluorescent dye Rubrene for an orange emission were fabricated. The basic structure of the fabricated device is a-NPD / nitro-DPVT / nitro- DPVT:Rubrene / BCP/ Alq3. Aluminum is used as the cathode material and ITO was anode material. The white light emission spectrum covers a wide range of the visible region and the Commission Internationale do I'E clairage (C.I.E.) coordinates of the emitted light was ((0.3347, 0.3515) at 14V. The turn voltage is as low as 2.5V and quantum efficiencies are $0.35\%$.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.1
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• pp.12-15
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• 2002

The physical properties, including magneto-optical and transport ones, of Ni$_2$MnG$_2$ alloy in the martensitic and austenitic states were investigated. The dependence of the temperature coefficient of resistivity on temperature shows kinks at the structural and ferro-para magnetic transitions. Electron-magnon and electron-phonon scattering are analyzed to be the dominant scattering mechanisms of the Ni$_2$MnG$_2$ alloy in the martensitic and austenitic states, respectively. The experimental real parts of the off-diagonal components of the dielectric function present two sharp peaks, one at 1.9 eV and the other at 3.2 eV, and a broad shoulder at 3.5 eV, all are identified by the band-structure calculations. These peak positions are coincident with those in the corresponding optical-conductivity spectrum, which is thought to originate from the single-spin state in Ni$_2$MnG$_2$ alloy.

• Korean Journal of Materials Research
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• v.17 no.1
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• pp.1-5
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• 2007

GaN thin fan were grown by spin coated colloidal GaOOH precursor. Polycrystalline GaNs with crystalline size of $10{\sim}100nm$ were grown on $SiO_2$ substrate. The shape of crystallite above $900^{\circ}C$ had the hexagonal plate and column type. X-ray diffraction patterns for them correspond to those of the hexagonal wurtzite GaN. With increasing droplets. i.e, thickness of deposited layers, XRD intensity increased. PL (photoluminescence) spectrum consisted with an weak near band-edge emission at 3.45 eV and a broad donor-acceptor emission band at 3.32 eV. From the low temperature PL measurement on GaN grown at $800^{\circ}C$ that the shallow donor-acceptor recombination induced emission was more intense than the near band-edge excitonic emission.

• Journal of environmental and Sanitary engineering
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• v.15 no.2
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• pp.102-111
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• 2000

As IR-sensor for detecting pollution material, the iron silicide has a fit band gap, high physicochemical stability at high temperature and good acid resistance. The growing film was formed with the Fe-Si bond and the organic compound because plasma resolved the injected precursors into various active species. In the Raman scattering spectrum, the Fe-Si vibration mode showed at 250 {TEX}$cm^{-1}${/TEX}. The FT-IR peak indicated that the various organic compounds were deposited on the films. The iron silicide was epitaxially grown to β-phase by the high energy of plasma. The lattice structure of films had [220]/[202] and [115]. The thickness of the films increased with the flow rate of silane. But rf-power increased with decreasing the thickness. The optical gap energy and the band gap were shown about 3.8 eV and 1.182∼1.194 eV. The band gap linearly increased and the formula was below: {TEX}$E_g^{dir}${/TEX}= 8.611×{TEX}$10^{-3}N_{D}${/TEX}＋1.1775

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.952-954
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• 2003

We report the photo-(PL) and electroluminescence (EL) properties of new conjugated compounds based on carbazolyl vinylene moiety, 3,3'-(1,4-phenylene di-2,1-ethenediyl) bis[9-ethyl-(E,E)-9H-carbazole](PEEC) and 3,3'-([1,1'-biphenyl]-4,4'-diyldi-2,1-ethenediyl)bis[9-ethyl-9H-carbazole](BPEEC), as emitting materials. The ITO/m-MTDATA/NPB/BPEEC/Alq3/LiF/Al device shows bluish-green EL spectrum at 490nm and turn-on voltage at 8V. PEEC shows bluish-green EL around ${\lambda}$ max=496nm and turn-on voltage at 6V and 2.4 Cd/A efficiency in ITO/m-MTDATA/NPB/PEEC/Alq3/LiF/Al device.

• Journal of The Korean Astronomical Society
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• v.39 no.4
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• pp.95-105
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• 2006

We have calculated the cosmic ray(CR) acceleration at young remnants from Type Ia supernovae expanding into a uniform interstellar medium(ISM). Adopting quasi-parallel magnetic fields, gasdynamic equations and the diffusion convection equation for the particle distribution function are solved in a comoving spherical grid which expands with the shock. Bohm-type diffusion due to self-excited $Alfv\acute{e}n$ waves, drift and dissipation of these waves in the precursor and thermal leakage injection were included. With magnetic fields amplified by the CR streaming instability, the particle energy can reach up to $10^{16}Z$ eV at young supernova remnants(SNRs) of several thousand years old. The fraction of the explosion energy transferred to the CR component asymptotes to 40-50 % by that time. For a typical SNR in a warm ISM, the accelerated CR energy spectrum should exhibit a concave curvature with the power-law slope flattening from 2 to 1.6 at $E{\gtrsim}0.1$ TeV.