• Journal of the Korean Vacuum Society
• /
• v.6 no.S1
• /
• pp.16-22
• /
• 1997

ion beam processing of materials for medical application has gained increasing interest in the last decade and the implantation of nitrogen into TI-6AI-4V to improve corrosive-wear performance is currently used for processing of total hip and knee joints. Oxides and nitrides of Ti, Zr, Al, Cr were deposited on TI-6AI-4V substrates by DC magnetron sputtering dual ion beam sputtering and ion beam assisted deposition. The cytotoxicity of these films were investigated by MTT method and showed comparable to untreated TI-6AI-4V Plasm-sprayed hydroxyapatite(HAp) coatings showed excellent cytotoxicity regardless of heat treatment. intermediate layer coatings of nitrides and oxides increased the bond strength of HAp to substrate by intrdducing chemical bond at interface. Heat treatment of HAp coatings also improved the chemical bond at interfaces and increased the bond strength of untreated TI-6AI-4V to 16.4 kg/$\textrm{cm}^2$ but still lower than 33.1 kg./$\textrm{cm}^2$ of ir oxide as a imtermediate layer caoting.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.6
• /
• pp.1063-1068
• /
• 2022

The modern society has become entry into the information age after the spread of Internet. In the information age, internet was developed from the wired access to the wireless Internet access. When a surge in demand for wireless Internet access, performance and speed of 2.4 and 5GHz band for Wi-Fi which leads to saturation of the communication was significantly fall. Accordingly, the communication of the 6GHz band for Wi-Fi 6E came to be interested. In this paper, we studied the design and fabrication of microstrip patch antenna to be used in wireless communication systems operating at around 6GHz band. To obtain antenna parameters such as patch size, inter patch space, antenna was simulated by HFSS(High Frequency Structure Simulator). From these parameters, slot microstrip patch antenna is fabricated using FR-4 of dielectric constant 4.4. The characteristics of fabricated patch type microstrip antenna were analyzed by network analyzer.

• Korean Journal of Pharmacognosy
• /
• v.47 no.3
• /
• pp.217-221
• /
• 2016

Endophytic fungi have yielded a variety of secondary metabolites so far. In the course of the project to find bioactive secondary metabolites from cultures of endophytic fungi, an isolate of Arthrinium phaeospermum (JS 0567) was selected for chemical investigation. A large scale culture of this strain in rice media was extracted with an organic solvent and the extract was subjected to a serious of chromatography, which led to six metabolites. Their chemical structures were elucidated as 2,3,6,8-tetrahydroxy-1-methylxanthone(1), 2,3,4,6,8-pentahydroxy-1-methylxanthone(2), 3,4,6,8-tetrahydroxy-1-methylxanthone(3), 3,6,8-trihydroxy-1-methylxanthone(4), 2,4,2',4',6'-pentahydroxy-6-methylbenzophenone(5), and 5,7-di hydroxy-3-methylphthalide(6) on the basis of spectroscopic data. To the best of our knowledge, this is the first study on the secondary metabolites from Arthrinium phaeospermum.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.4
• /
• pp.635-640
• /
• 2008

New gas mixtures are now finding applications such as interrupting media for high-voltage circuit breakers. These mixtures consist of a high content of carbon tetrafluoride($CF_4$) added to sulfur hexafluoride($SF_6$). Nowdays $SF_6$ has been established for the use in gas insulated substations due to its high insulation withstand level and good arc quenching capability. At this paper Breakdown characteristics were investigated for $SF_6/CF_4$ mixtures when AC voltage and standard lightning impulse voltage(LI) was applied in a needle-plane electrodes. And partial discharge(PD) experiments were carried out in the test chamber which was made in needle-plane electrode. And ${\Phi}$-Q-N distribution of partial discharge signals was analyzed. The total pressure of the $SF_6/CF_4$ mixtures was varied within the range of 0.1-0.5 Mpa in the test chamber. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of $SF_6$ at positive impulse voltage and the PD inception voltage was increased slightly when pressure of $SF_6/CF_4$ Mixtures was increased. Maximum PD inception voltage is showed in 80% SF6/20%$CF_4$.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.10
• /
• pp.1475-1481
• /
• 2002

The study was conducted to evaluate the effect of early feed restriction on growth, fat accumulation and meat composition in unsexed broiler chickens. In experiment 1, three hundred and fifty one-day-old broiler chicks were divided into 7 groups. Each treatment group was represented by five replicates of ten broilers each. One group was fed ad libitum as the control group and the other six groups were fed 25% ad libitum (25% multiplied by amount of feed intake of ad libitum chicks at the previous day) for 4 or 6 days, 50% ad libitum for 4 or 6 days, and 75% ad libitum for 4 or 6 days. In experiment 2, five hundred broiler chicks were divided into 10 groups. Each treatment group was represented by five replicates of ten broilers each. One group was fed ad libitum as the control group. Three initial age at which broilers were restricted (2, 4 or 6 days of age) and three type of feed restriction (physical restriction, meal feeding and diet dilution) ($3{\times}3$) were examined. They were restricted feeding for 6 days. Experimental results showed that broilers fed 25% ad libitum for 4-6 days tended to reduce leg meat fat with lower abdominal fat (p<0.05) (experiment 1). Breast meat fat was significantly higher in restricted broilers (p<0.01). Plasma triglyceride was higher in broilers fed 75% ad libitum for 4-6 days. In experiment 2, abdominal fat was lower in restricted broilers (p<0.05). Breast meat fat was significantly higher (p<0.01), whereas leg meat fat was significantly lower (p<0.05) in restricted broilers. Plasma triglyceride was significantly higher in physical feed restriction for 4 days, meal feeding for 4 days and diet dilution for 6 days (p<0.05). In conclusion, to reduce fat accumulation in abdomen and leg meat, broilers should be fed 25% ad libitum for 6 days started at 4 days, or subjected to meal feeding (6 hours per day for 6 days) started at 6 days.

• Archives of Pharmacal Research
• /
• v.13 no.4
• /
• pp.310-313
• /
• 1990

Hantzsch synthesis of 5-formyluracil (1) methyl acetoacetate (2) and methyl 3-aminocrotonate (3) gave 2, 6-dimethyl-4-(2, 4-dioxo-5-pyrimidy)-1, 4-dihydropyridine-3, 5-dicarboxylic acid dimethylester (4a) in 54.6 yield. As the same procedure, 1, 3-dimethyl-5-formyl-uracil (6) gave 2, 6-dimethyl-4-(1, 3-dimethyl-2, 4-dioxo-5-pyrimidyl)-1, 4-dihydropyridine-3, 5-dicarboxylic acid dimethyl easter (7a) IN 52.2% yield. 4a was methylated to afford 7a also in 52% yield.

• BMB Reports
• /
• v.32 no.4
• /
• pp.358-362
• /
• 1999

dTDP-D-glucose 4,6-dehydratase as an oxidoreductase catalyzes the conversion of dTDP-D-glucose to dTDP-4-keto-6-deoxy-D-glucose, which is essential for the formation of 6-deoxysugars. dTDP-D-glucose 4,6-dehydratase shows remarkable sterochemical convergence in which displacement of the C-6 hydroxyl group by a C-4 hydrogen proceeds intramolecularly with inversion of configuration. The reaction mechanism is known to be oxidation, dehydration, and reduction by bases mediating proton transfer and $NAD^+$ cofactor. In this study, the bases in the active site domain are proposed to be His-79 and His-300 from a comparison of the peptides of the dehydratase and UDP-D-glucose epimerase. His-79 and His-300 were mutated to prepare the mutants H79L (mutation of histidine to leucine at the 79th amino acid) and H300A (mutation of histidine to alanine at the 300th amino acid) by site-directed mutagenesis. The H79L protein was inactive, showing that His-79 participates in the reaction mechanism.

• Journal of Biosystems Engineering
• /
• v.19 no.4
• /
• pp.311-317
• /
• 1994

Warts and barks of apple trees were vector of White rot. Two devices removing warts and barks for the use of pest control on apple trees were developed and evaluated in this study, and their results are as follows ; 1. A total of 148 warts were examined to determine the average size. About 35 percent of the examined warts were 6~8mm long, 4~8mm wide and 4~6mm thick in size. About 30 percent of the examined warts were 4~6mm long, 2~4mm wide and 6~8mm thick in size. 2. Seventy-one percent of the examined barks removed were 4~8mm in thickness. 3. A blade with 30 degree of cutting angle required 3 to 22 percent less cutting energy than those with 15 and 45 degrees of cutting angles. 4. The cutting torque decreased from 31 N-cm to 12 N-cm with an increase of cutting speed from 26cm/s to 104cm/s for a feeding speed of 0.31 mm/s with the blade angle of 30 degrees. 5. The cutting torque increased from 6N-cm to 32N-cm with an increase of branch diameter from 6mm to 14mm for a feeding speed of 0.31 mm/s with the blade angle of 30 degrees. 6. Two devices mounted on a mower for removing warts and barks were evaluated and proved effective.

• Journal of the Korean Chemical Society
• /
• v.18 no.3
• /
• pp.157-170
• /
• 1974

The effects of ionic strength on the polynucleation reaction of tungstate ions and the protonized reaction of polytungstate ions have been investigated in the range of ionic strength from 1 M to 4 M KCl.The hexatungstate ions and the protonized forms of hexatungstate ions are formed in the tungstate solutions whose ionic strengths are 1 M to 4 M KCl. The equilibrium constants for the formation of hexatungstate ions and the protonized forms of hexatungstate ions are calculated in the range of ionic strength from 1 M to 4M KCl. The enthalpy changes for the formation of hexatungstate ions and the protonized forms of hexatungstate ions are as follows; $7H^++{6WO_4}^{2-}={HW_6O_{21}}^{5-}+3H_2O\;\;{\Delta}H^{\circ}=-62.4{\pm}0.6$$H^++{HW_6O_{21}}^{5-}={H_2W_6O_{21}}^{4-}\;\;{\Delta}H+_1^{\circ}=-4.12{\pm}0.10$$H^++{H_2W_6O_{21}}^{4-}={ H_3W_6O_{21}}^{3-}\;\;{\Delta}H_2^{\circ}=-4.36{\pm}0.30$ The free energy and entropy changes for the above reactions have been also calculated. A linear relation is formed between $log k_{6,7}$ and ionic strength, and $log k_1\;or\;log k_2\;vs{\cdot}{\mu}.$ $log k_{6,7}\;=\;D{\mu}+I,\;\;where\;D\;=\;1.66{\pm}0.02$$log k_1\;=\;D_1{\mu}+I_1,\;\;where\;D_1\;=\;-8.065{\pm}0.001$$log k_2\;=\;D_2{\mu}+I_2,\;\;where\;D_2\;=\;-0.376{\pm}0.006$

• Textile Coloration and Finishing
• /
• v.9 no.1
• /
• pp.44-49
• /
• 1997

Recent investigation and developments of A. Iqbal on diketo-pyrrolo-pyrrole (DPP) pigments has prompted us to synthesize and close observation of a few properties of these molecules. Described are synthesis, via 1-phenyl-2-ethoxycarbonyl-5-pyrrolinone intermediate, of asymmetric derivatives such as 1,4-Diketo-3-(4-chlorophenyl)-6-phenyl-pyrrolo-(3,4c)-pyrrole (4), 1,4-Diketo-3-(4-bromophenyl)-6-phenybpyrrolo-(3,4c)-pyrrole (5), 1,4-Diketo-3-(3-cyanophenyl)-6-phenyl-pyrrolo-(3,4c)-pyrrole (6), 1,4-Diketo-3-(4-cyanophenyl)-6-phenyl-pyrrolo-(3,4c)-pyrrole (7), 1,4-Diketo-3-(4-pyridyl)-6-phenyt-pyrrolo-(3,4c)-pyrrole (8), 1,4-Diketo-3-(3-pyridyl)-6-phenyl-pyrrolo-(3,4c)-pyrrole (9), 1,4-Diketo-3-(2-pyridyl)-6-phenyl-pyrrolo-(3,4c)-pyrrole (10), 1,4-Diketo-3-($\beta$-naphthyl)-6-phenyl-pyrrolo-(3,4c)-pyrrole (11), and UV-Vis absorption spectrum of the above compounds. Results from calculation of their absorption maxima using PISYSTEM are also described.