• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.6
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• pp.445-449
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• 2020

Non-volatile memory is approaching its fundamental limits with the Si₃N₄ storage layer, necessitating the use of alternative materials to achieve a higher programming/erasing speed, larger storage window, and better data retention at lower operating voltage. This limitation has restricted the development of the charge-trap memory, but can be addressed by using high-k dielectrics. The paper reviews the doping of nitrogen, titanium, and yttrium on high-k dielectrics as a storage layer by comparing MONOS devices with different storage layers. The results show that nitrogen doping increases the storage window of the Gd₂O₃ storage layer and improves its charge retention. Titanium doping can increase the charge capture rate of HfO₂ storage layer. Yttrium doping increases the storage window of the BaTiO₃ storage layer and improves its fatigue characteristics. Parameters such as the dielectric constant, leakage current, and speed of the memory device can be controlled by maintaining a suitable amount of external impurities in the device.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1300-1309
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• 2023

Simulated debris was synthesized using UO₂, Zr, and stainless steel and a heat treatment method under inert or oxidizing conditions. The primary U solid phase of the debris synthesized at 1473 K under inert conditions was UO₂, whereas a (U, Zr)O₂ solid solution formed at 1873 K. Under oxidizing conditions, a mixture of U₃O₈ and (Fe, Cr)UO₄ phases formed at 1473 K, whereas a (U, Zr)O_2+x solid solution formed at 1873 K. The leaching behavior of the fission products from the simulated debris was evaluated using two methods: the irradiation method, for which fission products were produced via neutron irradiation, and the doping method, for which trace amounts of non-radioactive elements were doped into the debris. The dissolution behavior of U depended on the properties of the debris and aqueous solution for immersion. Cs, Sr, and Ba leached out regardless of the primary solid phases. The leaching of high-valence Eu and Ru ions was suppressed, possibly owing to their solid-solution reaction with or incorporation into the uranium compounds of the simulated debris.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.6
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• pp.251-255
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• 2007

We made $(1-x)BCB-xBNT(BaNd_2Ti_4O_{12})$ (x=20, 30, 40, 50 vol%) composite thick film with a high dielectric constant and low loss by the hand casting method. Dielectric constant and dielectric loss of prepared thick film are measured at 1MHz and curing behavior of the film are observed through thermal analysis such as DSC. We investigated the effect of contents of BNT filler and curing behavior of film on dielectric properties of BCB-BNT composite. Dielectric constant increased with increasing BNT filler from 20 to 50 vol% and dielectric loss ($tan{\delta}$) decreased with increasing BNT filler. Dielectric constant and loss ($tan{\delta}$) of composite material was not nearly dependent on the curing behavior. But as a result of TCC (Temperature Characteristics of Coefficient) decreased with increasing the curing temperature, we confirmed that the curing of these composite system is most stable above $250^{\circ}C$.

• Analytical Science and Technology
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• v.14 no.4
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• pp.311-316
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• 2001

We have investigated the trace amount in an oriental medicine in oder to determine the geographical origin by using inductively coupled plasma-atomic emission spectrometry(ICP-AES) and chemometric anlysis with principal component analysis(PCA) and pattern recognition. Astragali Radix from several agricultural places in Korea was selected as an example of the oriental medicine and analyzed by ICP-AES. The dried Astragali Radix sample was treated with $HNO_3$ and $H_2O_2$, then digested using microwave oven. Elements such as Mg, Al, K, Ca, Ti, Mn, Fe, Cu, Zn, and Ba with different concentrations were found an used for the identification of the origin of agriculture places. Especially, the concentration of Al, Fe, Zn and Ti were employed to investigate the relationship between. Astragali Radix and the agricultural places by PCA and pattern recognition. We have made a program that is based on chemometrics in analytical spectroscopy. The results of the chemometrics analysis indicated that a distinction among Yechon and Chechon, Chungson, Kurye and Chinese Astragali Radix could be made. We believe that principal component analysis(PCA) and pattern recognition is a valuable tool to identify the origin of Astragali Radix in terms of the agricultural place.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.9
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• pp.56-63
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• 1999

Conventional method to improve the response time of the Cat-SPPCM was to increase fanning beam using cylindrical lens. But, in this case the temporal instability of this SPPCM is increased, and fanning beam plays a role as noise, so that it decreases the reflectivity. Thus, fanning beam must be controlled to improve the properties of SPPCM. In this paper, we propose the method to increase the reflectivity of SPPCM and decrease the response time by focusing line-shaped input beam into photorefractive crystal using cylindrical lens and decrease the temporal instability of output beam by using mixed-polarized beam instead of simple extraordinary polarized beam. Optical experiments show that the reflectivity of proposed SPPCM is increased twice and the response time is reduced by 15 times. Also, we observed that the temporal instability of SPPCM is reduced when the polarization angle of the mixed-polarized beam is between $10^{\circ}$ and $30^{\circ}$ . We used a $45^{\circ}-cut\;BaTiO_3$ crystal which has high electro-optical coefficients in optical experiments.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.9
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• pp.931-935
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• 2012

In this study, we fabricate and investigate low-temperature solid oxide fuel cells with a ceramic substrate/porous metal/ceramic/porous metal structure. To realize low-temperature operation in solid oxide fuel cells, the membrane should be fabricated to have a thickness of the order of a few hundreds nanometers to minimize IR loss. Yttrium-doped barium zirconate (BYZ), a proton conductor, was used as the electrolyte. We deposited a 350-nm-thick Pt (anode) layer on a porous substrate by sputter deposition. We also deposited a 1-${\mu}m$-thick BYZ layer on the Pt anode using pulsed laser deposition (PLD). Finally, we deposited a 200-nm-thick Pt (cathode) layer on the BYZ electrolyte by sputter deposition. The open circuit voltage (OCV) is 0.806 V, and the maximum power density is 11.9 mW/$cm^2$ at $350^{\circ}C$. Even though a fully dense electrolyte is deposited via PLD, a cross-sectional transmission electron microscopy (TEM) image reveals many voids and defects.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.7-10
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• 2007

Plant regeneration system from floral stem of Mymphoides indica via somatic embryogenesis was established. After four weeks of culture onto 1/2MS medium containing 2,4-D, pale-yellow globular structures and calluses were formed on the cut surface of floral stem explants. Upon transfer to 1/2MS basal medium, pale-yellow globular structures were developed into somatic embryos and normal plantlets. These results indicated that pale-yellow globular structures and calluses from floral stem were globular embryos and embryogenic calluses, respectively. The frequency of embryogenic callus formation from floral stem was reached to nearly 100% when floral stem was cultured onto 1/2Ms medium supplemented with low concentration of 2,4-D (0.1 to 0.3 mg/L). However, the higher concentration of 2,4-D resulted in decrease of the frequency of embryogenic callus formation. In this study, low concentration of 2,4-D had a stimulative role in embryogenic callus formation, whereas BA showed inhibitory role in callus formation. In comparison to floral stem, leaf explants showed low frequency of embryogenic callus formation. The highest frequency of embryogenic callus formation from leaf explants was 9.5% when leaf explants were cultured onto 1/2MS medium supplemented with 0.3 mg/L of 2,4-D. The plant regeneration system of Nymphoides indica established in this study, might be applied to mass proliferation, conservation of genetic resources and genetic transformation for molecular breeding.

• Journal of Sensor Science and Technology
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• v.10 no.6
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• pp.295-303
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• 2001

White emission thin film electroluminecent device was fabricated with ZnS for phosphor layers and BST ferroelectric thin film for insulating layers. The ZnS:Mn and $ZnS:SmF_3$ layers were used for emission of red color. Also the $ZnS:TbF_3$ and $ZnS:AgF_3$ layers were used to emission of green and blue color, respectively. And the fabrication conditions of the BST insulating layers were followings, that is, the composition ratio of target, substrate temperature, working pressure and operating gas ratio were $Ba_{0.5}Sr_{0.5}Ti_{0.3}$, $400^{\circ}C$, 30 mTorr and 9:1, respectively. The thickness of phosphor were 150 nm for each layers and the insulating layers of upper and bottom were 400 nm and 200 nm, respectively. The luminesence threshold voltage was $75\;V_{rms}$ and the maximum brightness of the thin film electroluminecent device was $3200\;cd/m^2$ at $100\;V_{rms}$.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.527-531
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• 2006

We have prepared organophilic inorganic particles and polyimide (PI) nanocomposite having excellent thermal stability and high dielectric constant that can be used for electronic application such as capacitor. We have chosen barium titanate (BT), a high dielectric constantmaterial and its surface was coated with nylon 6 to improve the affinity with PI. The FT-IR and TEM studies showed that the organophilic inorganic particle (BTN) has a polymer shell with thickness of 5 nm. We have suggested that it is possible to control the thickness of coating surface and also indicated the relationship between the ratio of inside and outside radius of BTN and the weight fraction of BT. The PI nanocomposite films based on poly(amic acid) and BTN were prepared by cyclodehydration reaction. The homogeneous dispersion of BTN in PI matrix was identified by using SEM. We have investigated the effect of BTN content on the coefficient of thermal stability, integral procedural decomposition temperature (IPDT), and dielectric constant of PI nanocomposite films.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.638-644
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• 2002

In this paper, we implemented a three dimensional image display system using stereogram and holographic optical memory techniques which can store many images and reconstruct them automatically. In this system, to store and reconstruct stereo images, incident angle of reference beam must be controlled in real time, so we used BPH(binary phase hologram) and LCD(liquid crystal display) for controlling reference beam. The reference beams are acquired by Fourier transform of BPHs which designed with SA(simulated annealing)algorithm, and the BPHs are represented on the LCD with the 0.05 seconds time interval using application software for reconstructing the stereo images. And input images are represented on the LCD without polarizer/analyzer for maintaining uniform beam intensities regardless of the brightness of input images. The input images and BPHs are edited using application software(Photoshop) with having the same recording scheduled time interval in storing. The reconstructed stereo images are acquired by capturing the output images with CCD camera at the behind of the analyzer which transforms phase information into brightness information of images. In output plane, we used a LCD shutter that is synchronized to a monitor that display alternate left and right eye images for depth perception. We demonstrated optical experiment which store and reconstruct four stereo images in BaTiO$_3$ repeatedly using the proposed holographic optical memory techniques.