• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• 제17권11호
• /
• pp.1212-1217
• /
• 2004

Red organic electroluminescent (EL) devices based on tris(8-hydroxyquinorine aluminum) (Alq$_3$) doped with red emissive materials, 4-(dicyanomethylene)-2-t-butyl -6-(l,1,7,7-tetramethyljulolidyl-9-enyl)4H-pyran (DCJTB). poly(3-hexylthiophene) (P3HT). rubrene and 4-dicyanomethylene-2-methyl-6[2-(2,3.6.7-tetrahydro-lH,5H-benzo-[i,j]quinolizin-8yl)vinyl]-4H-pyran (DCM2) were fabricated for applying to the red light source, The photoluminescence (pL) intensities of red emissive materials doped in Alq$_3$ are limited by the concentration quenching with increasing the doping ratio and the doping concentration of DCJTB, DCM2, P3HT and rubrene measured at the maximum intensity showed 5, 1, 0.5 and 2 wt%, respectively. Time-resolved PL dynamic results showed that the PL lifetime of red emissive materials doped in Alq$_3$ were increased more than the value of material itself. It means that the efficient energy transfer occurred in the mixed state and Alq$_3$ is a suitable host materials for red emissive materials, The device which was used DCJTB as a dopant achieved the best result of the maximum luminance of 594 cd/$m^2$ at 15 V and showed the chromaticity coordinates of x=0,624, y=0,371.

• Nuclear Engineering and Technology
• /
• 제54권5호
• /
• pp.1754-1759
• /
• 2022

The activity of gamma-ray emitting nuclides is calculated assuming that each gamma-ray is detected individually; thus, the magnitude of the coincidence summing signal must be considered during activity calculations. Here, the correction factor for the coincidence summing effect was calculated, and the detection efficiencies of two HPGe detectors were compared. The CANBERRA Inc. GC4018 high-purity Ge detector provided an estimate for the peak-to-total ratio using a point source to determine the coincidence summing correction factor. The ORTEC Inc. GEM60 high-purity Ge detector uses EFFTRAN in LVis to obtain the parameters of the detector and source model and the gamma-gamma and gamma-X match estimates, in order to determine the coincidence summing correction factor. Nuclide analyses, radioactivity comparisons, and analyses of reference material samples were performed utilizing certified reference materials to accurately determine the detection efficiencies. For both Co-60 and Y-88, the detection efficiency for a point source increased by an average of at least 12-13%, whereas the detection efficiency determined using LVis increased by an average of at least 13-15%. The calculated radioactivity values of the certified reference material and reference material samples were accurate to within 3% and 6% of the measured values, respectively.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 한국재료학회 1992년도 춘계학술발표회
• /
• pp.142-143
• /
• 1992

• Journal of the Korean Ceramic Society
• /
• 제46권5호
• /
• pp.528-533
• /
• 2009

High purity $\beta$-SiC powders were synthesized using sol-gel processing. TEOS and phenol resin were used as the starting material for the silicon source and carbon source, respectively. The process turned out to be capable of producing high purity SiC powder purity degree with 99.98 %. However, it was difficult to control the shape and size of $\beta$-SiC powders synthesized by sol-gel process. In this study, $\beta$-SiC powder with size of $1{\sim}5$ um an 30 nm were used as the seeds for $\beta$-SiC to control the $\beta$-SiC powder morphology. It was found that $\beta$-SiC powder seeds was effective to increase the powder average size of synthesized $\beta$-SiC using sol-gel process by acting as the preferred growing sites for $\beta$-SiC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• 제27권3호
• /
• pp.141-145
• /
• 2014

Tubular-shaped ZnO crystals were synthesized by thermal evaporation technique under air atmosphere. Mixture of Zn and Mg powder was used as the source material. The thermal evaporation and oxidation of Zn/Mg mixture were carried out for 1 hr at $1,000^{\circ}C$ and $1,200^{\circ}C$ under in air under atmospheric pressure. When only Zn powder was used as a source material, tetrapod-shaped ZnO crystals were synthesized. This provides that Mg played a key role in the formation of the tubular-shaped crystals. SEM images showed that the tubular-shaped ZnO crystals grew along [0001] direction. XRD spectrum revealed that the ZnO tubes had hexagonal wurtzite structure. Two emission peaks at 380 nm and 510 nm were observed in the room temperature cathodoluminescence spectrum.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
• /
• pp.124-127
• /
• 2003

The stochiometric $AgGaSe_2$ polycrystalline mixture of evaporating materials for the $AgGaSe_2$ single crystal thin film was prepared from horizontal furnance. To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal and semi-insulating GaAs(100) wafer were used as source material and substrate for the Hot Wall Epitaxy (HWE) system, respectively. The source and substrate temperature were fixed at $630^{\circ}C$ and $420^{\circ}C$, respectively. The thickness of grown single crystal thin films is $2.1{\mu}m$. The single crystal thin films were investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. From the photoluminescence measurement of $AgGaSe_2$ single crystal thin film, we observed free excition ($E_x$) observable only in high quality crystal and neutral bound excition ($D^{\circ}$,X) having very strong peak intensity. And, the full width at half maximum and binding energy of neutral donor bound excition were 8 meV and 14.1 meV, respectively. By Haynes rule, an activation energy of impurity was 141 meV.

• Vacuum Magazine
• /
• 제4권3호
• /
• pp.16-20
• /
• 2017

Graphene has emerged as a promising material for optoelectronic applications including as ultrafast and broadband photodetector, optical modulator, and nonlinear photonic devices. Graphene based devices have shown the feasibility of ultrafast signal processing for required for photonic integrated circuits. However, on-chip monolithic nanoscale light source has remained challenges. Graphene's high current density, thermal stability, low heat capacity and non-equilibrium of electron and lattice temperature properties suggest that graphene as promising thermal light source. Early efforts showed infrared thermal radiation from substrate supported graphene device, with temperature limited due to significant cooling to substrate. The recent demonstration of bright visible light emission from suspended graphene achieve temperature up to ~3000 K and increase efficiency by reducing the heat dissipation and electron scattering. The world's thinnest graphene light source provides a promising path for on-chip light source for optical communication and next-generation display module.

• Journal of the Korean Society for Nondestructive Testing
• /
• 제3권2호
• /
• pp.5-12
• /
• 1984

The purpose of this paper is to decide volume of crack by AE source wave analysis. The material studied in this paper was Titanium Alloy. Transient wave memory has 50 nano sampling time. The response function of specimens and transducer was obtained experimentally by use of specimens and transducer was obtained experimentally by use of breaking pencil lead as a reference simulated AE source, and the source waves were dertermined in terms of energy release-time functions explicitly through a time domain deconvolution. From experimental results, we can determine size of cracked volume.

• International Journal of Advanced Culture Technology
• /
• 제8권2호
• /
• pp.289-296
• /
• 2020

Software copyright are written in text form of documents and stored as files, so it is easy to expose on an illegal copyright. The IOT framework configuration and service environment are also evaluated in software structure and revealed to replication environments. Illegal copyright can be easily created by intelligently modifying the program code in the framework system. This paper deals with similarity comparison to determine the suspicion of illegal copying. In general, original source code should be provided for similarity comparison on both. However, recently, the suspected developer have refused to provide the source code, and comparative evaluation are performed only with executable code. This study dealt with how to analyze the similarity with the execution code and the circuit configuration and interface state of the system without the original source code. In this paper, we propose a method of analyzing the data of the object without source code and verifying the similarity comparison result through evaluation examples.

• Nuclear Engineering and Technology
• /
• 제46권6호
• /
• pp.837-846
• /
• 2014

A lead slowing down spectrometer (LSDS) is under development for analysis of isotopic fissile material contents in pyro-processed material, or spent fuel. Many current commercial fissile assay technologies have a limitation in accurate and direct assay of fissile content. However, LSDS is very sensitive in distinguishing fissile fission signals from each isotope. A neutron spectrum analysis was conducted in the spectrometer and the energy resolution was investigated from 0.1eV to 100keV. The spectrum was well shaped in the slowing down energy. The resolution was enough to obtain each fissile from 0.2eV to 1keV. The detector existence in the lead will disturb the source neutron spectrum. It causes a change in resolution and peak amplitude. The intense source neutron production was designed for ~E12 n's/sec to overcome spent fuel background. The detection sensitivity of U238 and Th232 fission chamber was investigated. The first and second layer detectors increase detection efficiency. Thorium also has a threshold property to detect the fast fission neutrons from fissile fission. However, the detection of Th232 is about 76% of that of U238. A linear detection model was set up over the slowing down neutron energy to obtain each fissile material content. The isotopic fissile assay using LSDS is applicable for the optimum design of spent fuel storage to maximize burnup credit and quality assurance of the recycled nuclear material for safety and economics. LSDS technology will contribute to the transparency and credibility of pyro-process using spent fuel, as internationally demanded.