• Journal of Korean Society of Industrial and Systems Engineering
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• 제47권3호
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• pp.86-94
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• 2024

In this study, an attempt was made to approximate the main characteristic values of Bi_0.5(Na_0.78K_0.22)_0.5TiO₃ (= BNKT) depending on the content of Fe₂O₃ additives, aiming to approach the values of lead(Pb) piezoelectric ceramic materials (PZT). Specifically, when the piezoelectric coefficient (d₃₃) value of lead(Pb) piezoelectric ceramic material (PZT polycrystalline ceramic powder) is 300[pC/N] or higher, it is applied for hard purposes such as ultrasonic welding machines and cleaning machines, and when it exceeds 330[pC/N], it is applied for soft purposes like piezoelectric sensors. In this study, research and development were conducted for devices with a piezoelectric coefficient (d₃₃) of 300[pC/N] or more for actuators. For this purpose, K⁺ exceeding 0.02 to 0.12 mol% was added to (Na_0.78K_0.22)_0.5Bi_0.5TiO₃ to analyze structural changes due to K⁺ excess, and (Na_0.78K_0.22)_0.5Bi_0.5TiO₃ + 8mol% K₂CO₃ Ti⁴⁺ was substituted with Fe³⁺ to manufacture lead-free piezoelectric materials. As a result, ceramics with Fe³⁺ substitution at x = 0.0075 yielded an average value of d₃₃ = 315[pC/N]. Furthermore, for ceramics with Fe³⁺ substitution at x = 0.0075, the average values of maximum polarization (P_max), residual polarization (P_rem), and coercive field (E_c) were found to be 39.63 μC/cm², 30.45 μC/cm², and 2.50 kV/mm, respectively. The reliable characteristic values obtained from the research results can be applied to linear actuator components (such as the zoom function of mobile cameras, LDM for skin care, etc.) and ultrasonic vibration components.

• Korean Journal of Agricultural Science
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• 제39권3호
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• pp.377-386
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• 2012

To reduce the saturation level of lard, solvent fractionation with hexane and acetone was carried out. The fatty acid compositions of lard were 1.5% myristic acid, 26.0% palmitic acid, 2.2%, palmitoleic acid, 12.1% stearic acid, 44.7% oleic acid, and 12.7% linoleic acid. Lard was fractionated by various conditions such as different fractionation temperatures (-15, 5, 10, $15^{\circ}C$), solvent ratios (1:1, 1:3, 1:5, 1:10, lard : solvent, w/v), and fractionation time (3, 6, 24 hr). At $-15^{\circ}C$, acetone was better for reducing the content (11.2%) of saturated fatty acids (SFA) than hexane (10.8%) when the 1:5 solvent ratio was used at 24 hr. Triacylglycerol (TAG) profiles were analyzed by reversed-phase high performance liquid chromatography based on the partition number (PN) of TAG molecules. The PN of major TAG species in lard were 46 (24.4%), 48 (55.7%), and 50 (19.9%). However, after fractionation (1:5, $5^{\circ}C$ and 24 hr), TAG species with a PN of 46 (34.2%), 48 (54.4%), and 50 (6.9%) were major components in acetone-fractionated lard (liquid part), while TAG species with a PN of 46 (26.0%), 48 (50.3%), and 50 (19.0%) were in hexane-fractionated lard, suggesting that fractionation with acetone resulted in maximal reduction of saturation level in lard.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제26권2호
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• pp.380-386
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• 2002

Damage behaviors induced in silicon carbide by an impact of particle having different material and size were investigated. Especially, the influence of the impact velocity of particle on the cone crack shape developed was mainly discussed. The damage induced by spherical impact was different depending on the material and size of particles. Ring cracks on the surface of specimen were multiplied by increasing the impact velocity of particle. The steel particle impact produced larger ring cracks than that of SiC particle. In the case of high velocity impact of SiC particle, radial cracks were produced due to the inelastic deformation at the impact site. In the case of the larger particle impact, the damage morphology developed was similar to the case of smaller particle one, but a percussion cone was farmed from the back surface of specimen when the impact velocity exceeded a critical value. The zenithal angle of cone cracks developed into SiC material decreased monotonically with increasing of the particle impact velocity. The size and material of particle influenced more or less on the extent of cone crack shape. An empirical equation, $\theta$= $\theta$$\sub$st/, v$\sub$p/(90-$\theta$$\sub$st/)/500 R$\^$0.3/($\rho$$_1$/$\rho$$_2$)$\^$$\frac{1}{2}$/, was obtained as a function of impact velocity of the particle, based on the quasi-static zenithal angle of cone crack. It is expected that the empirical equation will be helpful to the computational simulation of residual strength in ceramic components damaged by the particle impact.

• Journal of Pharmaceutical Investigation
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• 제7권1_4호
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• pp.38-50
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• 1977

A study on the mechanism of biliary and urinary excretion of chloramphenicol has been performed in the dog. 1) Chloramphenicol administered intravenously to dogs with ligated renal pedicle, readily appeared in bile greater than in plasma. 6.9% of a 50mg /kg i. v. dose of chloramphenicol were excreted into bile within 100 minutes. During the same periods of above experiment, the bile/plasma concentration ratios(B/P ratios) were 46 to 87. 2) Chloramphenicol injected into the vein of dog was rapidly excreted into urine. 18% of the administered dose were excreted into urine within 70 minutes. In the same periods of this experiment, Ccm/Ccr ratios were greater than 1.0 in most cases. 3) In experiment of simultaneous measurement of biliary and urinary excretion of chloramphenicol, Ccm/Ccr ratios were less than 1.0 and B/P ratios were 50 to 52. 4) In experiment measured simultaneously biliary and urinary excretion both Ccm/Ccr and $C^Hcm$(hepatic clearance) were significantly declined by probenecid, but not affected by 2,4-DNP and aminophylline although 2,4-DNP increased only bile flow and aminophylline both bile and urine volume. 5) Ccm/Ccr and $C^Hcm$ were increased in proportion to increment of plasma concentration ranging from 3.3 to 30 mg% of chloramphenicol. But when plasma concentration were increased to 70mg %, Ccm/Ccr were not increased and $C_Hcm$ were reduced about 30% in comparison with values obtajned at 30mg% of chloramphenicol. 6) Free/Bound(free to bouid from) ratios ranging from 1.0 to 90.0mg% of chloramphenicol were 76.2+3.72% $(mean{\pm}S.E.)$ Above results suggest that chloramphenicol is excreted into bile by a process of active trasport, that excretion of chloramphenicol into urine was made up with dual process, reabsorption and secretion, and that renal secretion was attained by active trasport process although renal reabsorption process could not understand.

• The Korean Journal of Ceramics
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• 제7권1호
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• pp.20-25
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• 2001

PbTiO$_3$ thin films were prepared by low-pressure thermal plasma deposition on (100)Pt/(100)MgO substrates. Mist of source material in which metal alkoxides are dissolved in 2-methoxyethanol was introduced into plasma through heating furnace and deposited onto substrates at $600^{\circ}C$. As-deposited PbTiO$_3$/Pt/MgO thin film prepared at 1.33$\times$10$^4$ Pa was grown epitaxially, but was consisted of many rectangular shaped grains, with many grain boundaries and it was impossible to measure electric properties. As-deposited film prepared at 1.00$\times$10$^4$ Pa showed weak peaks of X-ray diffraction and the film was not grown epitaxially. On the other hand, the film after annealed at $700^{\circ}C$ showed strong diffraction peaks and epitaxial growth was also observed. For annealed film, moreover, no clear grain boundaries were observed. The value of ${\varepsilon}_r$, tan${\delta}$, Pr and Ec of annealed film were 160, 3.2%, 10.4${\mu}$C.cm$^-2$ and 51.2kV.cm$^-1$, respectively. Since the composition, Pb/Ti, measured by EDS attaching to SEM changed point by point, the distribution of composition in annealed film was investigated and found out several relations between composition and electric properties. At stoichiometric composition, Pr and Ec showed the lowest value and they gradually became large as composition deviated from stoichiometric one. Moreover, the value of ${\varepsilon}_r$ became gradually large as the ratio of Ti became high.

• Proceedings of the KAIS Fall Conference
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• 한국산학기술학회 2010년도 추계학술발표논문집 1부
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• pp.488-490
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• 2010

최근 심각한 환경오염 문제와 화석 에너지 고갈로 차세대 청정 에너지 개발에 대한 중요성이 증대되고 있다. 그중에서 태양정지는 공해가 적고, 자원이 무한적이며 반 영구적인 수명을 가지고 있어 미래에너지 문제를 해결할 수 있는 에너지원으로 기대되고 있다. 본 연구에서는 P3HT(regioregular poly(3-hexylthiophene))와 PCBM(fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester)을 전자 도너와 억셉터 물질을 하나의 브랜드로 광 활성층을 형성하는 BHJ(bulk hetero junction)구조를 갖는 고분자 유기 박막 태양전지를 각각 Toluene, Mono-Chlorobenzene, Dichlorobenzene에 $60^{\circ}C$, 200rpm으로 약 12시간동안 1wt%로 교반(Stirring)한 후에 중량비(1:1 wt%)로 혼합하여 스핀코팅(Spin-coating)으로 제작하였고, 완성된 소자의 광활성층 면적은 0.04cm2이며, $150^{\circ}C$에서 후속 열처리 공정을 통해 특성 향상이 측정 되었다. 태양전지 소자 구조는 Glass / ITO / PEDOT:PSS / P3HT : PCBM / Al이다. 전류-전압, FF(Fill Factor), 변환효율 측정을 위해 solar simulator를 AM1.5 조건(100 mW/cm2)으로 이용하였으며, 소자의 최대 전류밀도는 12mA/$cm^2$, 개방전압은 0.566V이고 F.F(Fill Factor)는 55.2%이고 변환효율은 3.7%이다. 후속 열처리후 더욱 좋은 성능을 갖게 되었고, 최대 효율은 Dichl orobenzene일 때 이다.

• Korean Journal of Food Science and Technology
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• 제22권2호
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• pp.129-133
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• 1990

The strain of Nuruk yeat No. 15 (NY-15) which ferments lactose in milk was Isolated from Nuruk and identified as Saccharomyces marxianus according to the API 20C profile index. The lactose hydrolysing ability of NY-15 was similar to that Saccharomyces fragilis ATCC 8583 which has ${\beta}-galactosidase$ activity. Its optimum growth temperature, pH and time for the production of maximum enzyme activity showed $28^{\circ}C$, 4.5 and 28hr, respectively. Galactose as well as sucrose as carbon sources, and urea as nitrogen source Increased the production of enzyme. In order to test the production of alcohol, NY-15 was inoculated in whey medium and whey medium added with sugar. In the former, NY-15 produced 2% alcohol and in the latter, it showed 12% alcohol production. The optimal medium pH for lactose hydrolysis of NY-15 is 4.5, whereas that of Saccharomyces fragilis ATCC 8583 is 3.5

• Journal of Microbiology and Biotechnology
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• 제10권2호
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• pp.238-243
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• 2000

An exoinulinase (${\beta}-D-fructofuranosidase$) gene was cloned by chromosome walking along the upstream region of the endoinulinase gene of Pseudomonas mucidolens isolated from soil. the exoinulinase gene consisted of an ORF of 0,506 bp encoding a polypeptide of 501 amino acids with a deduced molecular weight of 55,000. The exoinulinase produced by the recombinant Escherichia coli $DH5{\alpha}$ strain was also purified to homogeneity as determined by SDS-PAGE and a zymogram. The molecular weight of the purified exoinulinase according to both SDS-PAGE and gel filtration matched the deduced molecular weight of the protein described above, thereby indicating that the native form of the exoinulinase was a monomer. The purified enzyme hydrolyzed activity value of 2.0. Furthermore, no inulo-oligomers were liberated from the inulin substrate in the enzymatic reaction mixtures incubated for 90 min at $55^{\circ}C$. Taken together, these results indicate that the purified ${\beta}-D-fructofuranosidase$ was an exoinulinase. The pH and temperature optima of the exoinulinase were pH 6.0 and $55^{\circ}C$, respectively. the enzymehad no apparent requirement for a cofactor, and its activity was completely inactivated by $Ag^{+},{\;}Hg^{2+},{\;}and{\;}Zn^{2+}$. Kinetic experiments gave $K_m,{\;}V_{max},{\;}and{\;}K_{cat}$ values for inulin of 11.5 mM, 18 nM/s, and $72{\;}s^{-1}$, respectively. the exoinulinase was fairly stable in broad pH conditions (pH 5-9), and at pH 6.0 it showed a residual activity of about 70% after 4 h incubation at $55^{\circ}C$.

• Journal of Hydrogen and New Energy
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• 제18권4호
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• pp.452-457
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• 2007

Titanium foil and mesh(anodized tubular $TiO_2$ electrode, ATTE) were anodized in a bath at $5^{\circ}C$ with 20V external bias applied, then annealed at different temperatures($450^{\circ}C{\sim}850^{\circ}C$) to obtain tubular $TiO_2$ on the Ti substrate. The prepared sample was used to investigate rate of hydrogen production as well as Cr(VI) reduction. The ATTEs annealed at relatively lower temperatures showed higher activity than those at relatively higher temperatures. In particular, the Cr(VI) reduction was pH-dependent. To improve photocatalytic Cr(VI) reduction with the ATTEs, two configurations, fixing foil type and rotating mesh type, were also compared. As a result, the rotating mesh type was much more effective for Cr(VI) reaction than the former due to the more efficient use of the light. In the rotating type reactor, as the rotating speed increased, the rate of the Cr(VI) reduction was getting faster.

• Asian Pacific Journal of Cancer Prevention
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• 제13권3호
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• pp.1031-1038
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• 2012

Background: Turmeric ($Curcuma$ $longa$) has been shown to possess anti-inflammatory, antioxidant and antitumor properties. However, despite the progress in research with $C.$ $longa$, there is still a big lacuna in the information on the active principles and their molecular targets. More particularly very little is known about the role of cell cycle genes $p57^{kip2}$ and Rad9 during chemoprevention by turmeric and its derivatives especially in prostate cancer cell lines. Methods: Accordingly, in this study, we have examined the antitumor effect of several extracts of $C.$ $longa$ rhizomes by successive fractionation in clonogenic assays using highly metastatic PC-3M prostate cancer cell line. Results: A mixture of isopropyl alcohol: acetone: water: chloroform: and methanol extract of $C.$ $longa$ showed significant bioactivity. Further partition of this extract showed that bioactivity resides in the dichloromethane soluble fraction. Column chromatography of this fraction showed presence of biological activity only in ethyl acetate eluted fraction. HPLC, UV-Vis and Mass spectra studies showed presence three curcuminoids in this fraction besides few unidentified components. Conclusions: From these observations it was concluded that the ethyl acetate fraction showed not only inhibition of colony forming ability of PC-3M cells but also up-regulated cell cycle genes $p57^{kip2}$ and Rad9 and further reduced the migration and invasive ability of prostate cancer cells.