• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.1
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• pp.40-49
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• 2001

We have developed a repeatable process of forming uniform, small-size and high-density self-assembled Si nano-crystals. The Si nano-crystals were fabricated in a conventional LPCVD (low pressure chemical vapor deposition) reactor at $620^{\circ}c$ for 15 sec. The nano-crystals were spherical shaped with about 4.5 nm in diameter and density of $5{\times}l0^{11}/$\textrm{cm}^2$. More uniform dots were fabricated on nitride film than on oxide film. To take advantage of the above-mentioned characteristics of nitride film while keeping the high interface quality between the tunneling dielectrics and the Si substrate, nitride-oxide tunneling dielectrics is proposed in n-channel device. For the first time, the single electron effect at room temperature, which shows a saturation of threshold voltage in a range of gate voltages with a periodicity of ${\Delta}Ｖ_{GS}\;{\approx}\;1.7{\;}V$, corresponding to single and multiple electron storage is reported. The feasibility of p-channel nano-crystal memory with thin oxide in direct tunneling regime is demonstrated. The programming mechanisms of p-channel nano-crystal memory were investigated by charge separation technique. For small gate programming voltage, hole tunneling component from inversion layer is dominant. However, valence band electron tunneling component from the valence band in the nano-crystal becomes dominant for large gate voltage. Finally, the comparison of retention between programmed holes and electrons shows that holes have longer retention time.

• Current Research on Agriculture and Life Sciences
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• v.7
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• pp.153-163
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• 1989

The activity changes and biochemical properties of ${\beta}$-gal in tomato fruits during ripening were investigated. The total activity was increased during ripening and three isoenzymes (${\beta}$-gal I, II and III) were purified through DEAE Sephadex A-50 and Sephadex G-100 column chromatography. The activities of ${\beta}$gal isoenzymes (${\beta}$-gal I, II and III) during ripening were 69.8, 31.8 and 170.0 units in mature green phase, while those were 48.7, 88.4 and 136.8 units in Red phase, respectively. As the ripening proceeded the activities of ${\beta}$-gal I and III were some what decreased but the activity of ${\beta}$-gal II was incresed more than 2.8 fold. The optimum pH of ${\beta}$-gal I, II and III were 3.9, 4.2 and 3.9 and the optimum temperature of those were $60^{\circ}C$, $56^{\circ}C$ and $60^{\circ}C$, respectively. All isoenzymes were stable at pH 3.6~6.0 and lost their activity about 50% when it heated at $55^{\circ}C$ for 5 minute. $Mg^{{+}{+}}$-activated the three isoenzymes but $Ca^{{+}{+}}$ and SDS inhibited about 30~40%. $Hg^{{+}{+}}$ inhibited completely. The km value of ${\beta}$-gal I, II and III was 0.36mM, 0.63mM and 0.45mM, reaction rate was rapidly increased until the concentration of substrate was $6.0{\times}10^{-5}M$.

• BMB Reports
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• v.34 no.6
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• pp.559-565
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• 2001

Protein carboxyl O-methyltransferase (E.C.2.1.1.24) may play a role in the repair of aged protein that is spontaneously incorporated with isoaspartyl residues. The porcine brain carboxyl O-methyltransferase was cloned in the pET32 vector, and overexpressed in E.coh (BL21) that harbors pETPCMT, which encodes 227 amino acids, including tagging proteins at the N-terminus. The protein sequence of the cloned porcine brain PCMT (r-pbPCMT) shares a 98% identity with that of human erythrocyte PCMT and rat brain PCMT. It is 100% identical with that of bovine brain. The r-pbPCMT was purified using Ni-NTA affinity chromatography and digested by enterokinase in order to remove the protein tags. Then Superdex 75HR gel filtration chromatography was performed. The r-pbPCMT exhibited similar in vitro substrate specificities with the PCMT that was purified from porcine brain. The molecular weight of the enzyme was estimated to be 24.5 kDa on the SDS polyacrylamide gel electrophoresis. The $K_m$ value was $1.1{\times}10^{-7}\;M$ for S-adenosyl-L-methionine. S-adnosyl-L-homocysteine was a competitive type of inhibitor with the $K_i$ value of $1.38{\times}10^{-4}\;M$. The enzyme has optimal activity at pH 6.0 and $37^{\circ}C$. These results indicate that the expressed enzyme is functionally similar to the natural protein. It also suggests that it may be a suitable model to further understand the function of the mammalian enzyme.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.354-362
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• 2009

This study was performed to develop a suitable nutrient solution for standard rose substrate culture in a closed hydroponic system. 1/4, 1/2, 2/3 and 1 strength of the nutrient solution made by Japan National Institute of Vegetable and Tea Science (JNIVT) were supplied. The photosynthesis rate, quality and growth of cut flower were higher in the 1/2 and 2/3 strength of nutrient solution during high and low temperature period. Based on the above results, optimum nutrient solutions (UOS) were composed by nutrientwater (n/w) absorption ratio with 1/2S ($NO_{3^-}N$ 6.8, $NH_{4^-}N$ 0.7, $PO_{4^-}P$ 2.0, K 3.8, Ca 3.0, Mg 1.2, $SO_{4^-}S$ $1.2me{\cdot}L^{-1}$) at high temperature season and 2/3($NO_{3^-}N$ 9.7, $NH_{4^-}N$ 0.8, $PO_{4^-}P$ 2.2, K 5.0, Ca 3.9, Mg 1.5, $SO_{4^-}S$ $1.5me{\cdot}L^{-1}$) at low temperature season. The results of suitability examination showed that the EC level in newly composed nutrient solution (UOS) was more stable than other nutrient solutions due to its large amount of calcium and potassium. The growth of cut flower cultivated with UOS was higher than those of other nutrient solutions. Especially, the yield of cut flowers in UOS nutrient solution increased 1.4 times than that of other nutrient solution treatments. Consequently, the new nutrient solution investigated in this experiment was suitable for rose cultivation in a closed hydroponic system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1295-1296
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• 2008

Hydrogen peroxide ($H_2O_2$) biosensor is one of the most developing sensors because this kind of sensors is highly selective and responds quickly to the specific substrate. Hemoglobin (Hb) has been used as ideal biomolecules to construct hydrogen peroxide biosensors because of their high selectivity to $H_2O_2$. The direct electron transfer of Hb has widely investigated for application in the determination of $H_2O_2$ because of its simplicity, high selectivity and intrinsic sensitivity. An electrochemical detection for hydrogen peroxide was investigated based on immobilization of hemoglobin on DNA/Fe(pyterpy)$^{2+}$ modified gold electrode. The pyterpy monolayers were firstly an electron deposition onto the gold electrode surface of the quartz crystal microbalance (QCM). It is offered a template to attach negatively charged DNA. The fabrication process of the electrode was verified by quartz crystal analyzer (QCA). The experimental parameters such as pH, applied potential and amperometric response were evaluated and optimized. Under the optimized conditions, this sensor shows the linear response within the range between $3.0{\times}10^{-6}$ to $9.0{|times}10^{-4}$ M concentrations of $H_2O_2$. The detection limit was determined to be $9{\times}10^{-7}$ M (based on the S/N=3).

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.4
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• pp.312-317
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• 2004

High dose ($3{\times}10^{16}cm^{-2}$) implantation of Fe or Ni ions into bulk, single-crystal ZnO substrates was carried out at substrate temperature of ${\sim}350^{\circ}C$ to avoid amorphization of the implanted region. The samples were subsequently annealed at $700^{\circ}C$ to repair some of the residual implant damage. X-Ray Diffraction did not show any evidence of secondary phase formation in the ZnO. The Ni implanted samples remained paramagnetic but the Fe-implanted ZnO showed evidence of ferromagnetism with an approximate Curie temperature of ${\sim}$240K. Preliminary X-Ray Photoelectron Spectroscopy measurements showed the Fe to be ill the 2+ oxidation state. The earrler density in the implanted region still appears to be too low to support carrier-meditated origin of the ferromagnetism and formation of bound magnetic polarons may be one potential explanation for the observed magnetic properties, No evidence of the Anomalous Hall Effect could be found in the Fe-implanted ZnO, but its transport properties were dominated by the conventional or ordinary Hall effect.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.83-83
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• 1995

The increase of population and industrial activities had brought into eutrophication in the Nakdong river. A remarkable acceleration of eutrophication brought about serious problems for water supply. Therefore, for the purpose of conservation of water quality in the Nakdong river it is necessary to control nutrients. MBOD method was use to evaluate algal growth limiting factor and algal growth potential in the Nakdong river from June to August 1994. The modified biochemical oxygen demand(MBOD) depends on the amount of available inorganic nutrient and organic substrate during 5 day incubation in the dark at 20$^{circ}C$. The MBOD assay depends on inorganic nutrients such as P and N as well as reduced carbon and called the MBOD, the MBOD-P, and the MBOD-N, respectively. The results of bioassay by MBOD(Modified BOD) method showed that the MBOD, MBOD-P and MBOD-N value were found to be in the ranges of 3.8∼96.0 mg$O_2$/l, 5.6∼94.0 mg$O_2$/l and 42.0∼220 mg$O_2$/l, respectively. And the the bioassay value was found to be the highest in Koryong area and the lowest in Waekwan area throughout the Nakdong river. The variations of MBOD-P and MBOD-N value showed similar tendencies to the variations of phosphorus and nitrogen value, respectively. By MBOD method, the relationships of MBOD, MBOD-P and MBOD-N value were MBOD ≒ MBOD-P 《 MBOD-N. The MBOD value was nearly equal to the MBOD-P value, and the MBOD-N value was 3 to 20 times more than the MBOD-P value, approximately. Therefore, in the Nakdong river, phosphorus was the limiting factor for algal growth during summer season. The algal growth potential as the concentration of chlorophyll-a in the summer was maximum 5 times more than standing crop as it.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.96-113
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• 1996

It has been found that the misfit dislocations in heavily boron-doped layers originate from wafer edges. Moreover, the propagation of the misfit dislocation into a heavily boron-doped region can be suppressed by placing a surrounding undoped region. Using a surrounding undoped region the disloction-free heavily boron-deoped silicon membranes have been fabricated. The measured surface roughness, fracture strength, and residual tensile stress of the membrane are 20.angs. peak-to-peak, 1.39${\times}$10$^{10}$ and 2.7${\times}$10$^{9}$dyn/cm$^{2}$, while those of the conventional heavily boron-doped silicon membrane with high density of misfit dislocations are 500 peak-to-peak, 8.27${\times}$10$^{9}$ and 9.3${\times}$10$^{8}$dyn/cm$^{2}$ respectively. The differences between these two membranes are due to the misfit dislocations. Young's modulus has been extracted as 1.45${\times}$10$^{12}$dyn/cm$^{2}$ for both membranes. Also, the effective lattice constant of heavily boron-doped silicon, the in-plane lattice constant of the conventional membrane, and the density of misfit dislocation contained in the conventional membrane have been extracted as density of misfit dislocation contained in the conventional membrane have been extracted as density of misfit dislocation contained in the conventional membrane have been extracted as 5.424.angs. 5.426.angs. and 2.3${\times}$10$^{4}$/cm for the average boron concentration of 1.3${\times}$10$^{20}$/cm$^{-23}$ cm$^{3}$/atom. Without any buffer layers, a disloction-free lightly boron-doped epitaxial layer with good crsytalline quality has been directly grown on the dislocation-free heavily boron-doped silicon layer. X-ray diffraction analysis revealed that the epitaxial silicon has good crystallinity, similar to that grown on lightly doped silicon substrate. The leakage current of the n+/p gated diode fabricated in the epitaxial silicon has been measured to be 0.6nA/cm$^{2}$ at the reverse bias of 5V.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.718-726
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• 2010

A selected fungal strain, for production of the raw-starchdigesting enzyme by solid-state fermentation, was improved by two repeated sequential exposures to ${\gamma}$-irradiation of $Co^{60}$, ultraviolet, and four repeated treatments with Nmethyl-N'-nitrosoguanidine. The mutant strain Aspergillus sp. XN15 was chosen after a rigorous screening process, with its production of the raw-starch-digesting enzyme being twice that of usual wild varieties cultured under preoptimized conditions and in an unsupplemented medium. After 17 successive subculturings, the enzyme production of the mutant was stable. Optimal conditions for the production of the enzyme by solid-state fermentation, using wheat bran as the substrate, were accomplished for the mutant Aspergillus sp. XN15. With the optimal fermentation conditions, and a solid medium supplemented with nitrogen sources of 1% urea and 1% $NH_4NO_3$, 2.5 mM $CoSO_4$, 0.05% (v/w) Tween 80, and 1% glucose, the mutant Aspergillus sp. XN15 produced the raw-starch-digesting enzyme in quantities 19.4 times greater than a typical wild variety. Finally, XN15, through simultaneous saccharification and fermentation of a raw rice corn starch slurry, produced a high level of ethanol with $Y_{p/s}$ of 0.47 g/g.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.553-557
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• 1999

Five fungi (mushrooms), Daedaleopsis styracina, Trichaptum abietium, Coriolus versicolor, Pisolithus tinctorius and Tricholomopsis decora, were screened and examined the fibrinolytic activity and specificity. The extracts of mushrooms showed a level of fibrinolytic activity that was about 3-4 times higher than that of plasmin 1.0 unit. In particular, Pisolithus tinctorius of them showed the greatest enzyme activity (4.71 plasmin unit/mL) by fibrin plate assay, and the highest specificity (1.32 plasmin unit/mL) using chromogenic substrate (N-p-Tosyl-Gly-Pro-Lys p-nitroanilide) by Tricholomopsis decora. And the same molecular mass 54 and 61kDa showing the fibrinolytic activity obtained from all fruiting bodies were confirmed, and it was found that Trichaptum abietium and Tricholomopsis decora have a strong fibrinolytic enzyme with an apparent size of 100 kDa and 84 kDa, respectively on SDS-fibrin zymography activity assay.