• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.3
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• pp.180-184
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• 2002

In this paper, the electrical properties of PVD Ta and $TaN_x$ gate electrodes on $SiO_2$ and their thermal stabilities are investigated. The results show that the work functions of $TaN_x$ gate electrode are modified by the amount of N, which is controlled by the flow rate of $N_2$during reactive sputtering process. The thermal stability of Ta and $TaN_x$ with RTO-grown $SiO_2$ gate dielectrics is examined by changes in equivalent oxide thickness (EOT), flat-band voltage ($V_{FB}$), and leakage current after post-metallization anneal at high temperature in $N_2$ambient. For a Ta gate electrode, the observed decrease in EOT and leakage current is due to the formation of a Ta-incorporated high-K layer during the high temperature annealing. Less change in EOT and leakage current is observed for $TaN_x$ gate electrode. It is also shown that the frequency dispersion and hysteresis of high frequency CV curves are improved significantly by a post-metallization anneal.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.175-180
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• 1997

새로운 복합페로브스카이트계 고용체 (1-x)Ba(Mg1/3Ta2/3)O3-xLa(Mg2/3Ta1/3)O3(x=0.0-1.0)를 설계하고 조성에 따른 고용체의 결정구조의 변화 및 MPB(Morphotropic Phase Boundary)를 분말 XRD를 이용하여 분석하였다. 초격자회절선의 변화로부터 MBT에 10mol%의 LMT를 치환함에 따라 1:2에서 1:1로의 규칙화타입의 전이가 일어남을 알 수 있었다. 면심입방정구조 영역(0.10.8조성의 경우, 주회절선의 피이크분리 및 새로운 회절선들로부터 격자비틀림의 형태가 단사정임을 알 수 있었다.

• Journal of the Korean Ceramic Society
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• v.31 no.2
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• pp.147-154
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• 1994

The imperfections of LiTaO3 crystals grown from the Pt-Rh and the Ir crucible were investigated with X-ray diffraction, optical and electron microscope. The growth direction was <100>h and the plane parallel to the plane connecting two main growth ridges was (012)h which would be the main cleavage plane. The dislocation density in the specimen cut parallel to (012)h plane increased with polishing time and the inverted ferroelectric microdomains were induced based on this dislocations. Such imperfections as 180$^{\circ}$ domains, microcracks, dislocations and stacking faults. could be found in the LiTaO3 crytals. The crystal contaminated with lots of Rh form Pt-Rh crucible during the crystal growing under air atmosphere contained more imperfections. The main cleavage plane and subgrain boundary parallel to its growing axis might be the main source of reducing the mechnical strength during the wafering process.

• Advances in materials Research
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• v.2 no.3
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• pp.173-180
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• 2013

Lead-free complex perovskite ceramics $NaMeO_3$ ($Me{\equiv}Nb$, Ta) were synthesized using conventional solid state reaction technique and characterized by structural, FTIR and electrical (dielectric and ac conductivity) studies. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software. XRD analysis of the compound indicated the formation of single-phase orthorhombic structure with the space group Pmmm (47). Dielectric studies showed the diffuse phase transition at $394^{\circ}C$ for $NaNbO_3$ and $430^{\circ}C$ for $NaTaO_3$. Ac conductivity in both the compounds follows Jonscher's power law.

• Journal of the Korean Magnetics Society
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• v.15 no.3
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• pp.177-180
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• 2005

Ferroelectric $LiTaO_3$ single crystals, grown by the Czochralski method, were thermally treated at temperature $1000^{\circ}C\;and\;1100^{\circ}C$. Electron paramagnetic resonance (EPR) study of stoichiometric $LiTaO_3$ and thermally treated $LiTaO_3$ crystals has been investigated by employing an X-band spectrometer. From the $Fe^{3+}$ EPR spectra, it turned out that there is no change of site location and local site symmetry around $Fe^{3+}$ impurity ion between stoichiometric and thermally treated $LiTaO_3$ single crystals. We confirmed that the ionic state of $Fe^{3+}$ ion changed after thermal treatment. The EPR parameters of $Fe^{3+}$ ion in $LiTaO_3$ single crystals are determined with effective spin Hamiltonian.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.475-479
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• 2004

The proteinpolysaccharides (PPS) from Polyporus umbellatus (P. umbellatus) screlotium is composed by 78.2% of saccharide, 16.8% of protein, and 4.0% of ash. PPS from P. umbellatus showed antitumor activities against 180 solid tumor in ICR mice at the concentration of 20-160 mg/kg/day. PPS from P. umbellatus inhibited cell viability to 47.4% and 45.0% in leukemia cell lines, L-1210 and K-562 cells at 50-400 $\mu\textrm{g}$/mL concentration, respectively. But the hall mark of cell apoptosis, DNA fragmentation was not observed at those concentration. 2.5-10.0% of PPS from P. umbellatus inhibited mutagenecity evoked by 2-nitrofluorene and sodium azide in Salmonella typhimurium TA 98 and TA 100. From these results, it is suggested that the PPS of P. umbellatus has antitumor and antimutagenic effect, and its cytotoxic effect may not be ascribed to the apoptosis.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.1-7
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• 2011

Sound waves and acoustic energy generated by two identical TA (ThermoAcoustic) lasers were analyzed and studied. One end of the ceramic stack was heated by a thin NiCr wire wound around that end. The other end of the stack was cooled by natural convection of atmospheric air. The wavelength of the sound waves generated by a single TA laser was four times the tube length and the amplitude of the waves increased with the heating rate. SPL (SoundPressure Level) meters and microphones were employed to measure and study the sound waves at different distances from the glass tube opening and at the focusing point of the TA laser pair for different laser position arrangements. The sound waves of the two TA lasers at the focusing point were found to be almost 180 degrees out of phase when the openings of the two lasers were very close to each other and the angle between the laser axes was small. When the two TA lasers were placed far apart, the sound wave amplitudes and the phase difference between the two laser outputs varied periodically with time. The frequencies of the sound waves changed when the openings of the two TA lasers were in close vicinity and the angle between the laser axes exceeded a certain value. In this case, the glass tube opening was no longer a pressure anti-node and the wavelength of the fundamental mode was not equal to four times the tube length.

• TTA Journal
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• s.48
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• pp.172-180
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• 1996

지난 4월, 향후 유럽 정보사회를 겨냥한 효율적 표준화 추진을 위해 TFIG(Task Force Implementation Group)에서 제안한 ETSI(European Telecommunications Standards Institute)의 표준화 조직구조 개편 요구에 따라 기존 ETSI의 기술 총회(TA : Technical Assembly)는 지난 25차 회의를 마지막으로 그간의 기술총회 활동을 마감하고 새로이 25명으로 구성된 이사회(Board) 체계로 변경되어진다. 이에 본 고에서는 지난 96년 10월에 열렸던 마지막 기술총회 참석 결과를 정리하고, 새로운 ETSI 조직 구조 변경에 따른 변화를 살펴보고자 한다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.175-180
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• 1993

The methanol extracts of perilla leaves reduced the mutagenicities mediated by of aflatoxin B$_1$(AFB$_1$), 3-amino-l-methyl-5H-pyrido (4,3-b) indole (Trp-P-2) and Benzo(a)pyrene (B(a)p) in Salmonella typhimurium TA98 and TA100. The methanol extracts were more fractionated, and the fractions of hexane and butanol revealed the antimutagenic activities against AFB$_1$ and B(a)p. The production of malondialdehyde (MDA) was decreased when the methanol extracts of perilla leaves were added to the system. The significantly higher antioxidative activity was observed in the butanol fraction. 2-Propyl furan, ethanedioic acid, dibutyl ester, benzaldehyde, 2-methyl-2-ethyl-3-hydroxy-propanoic acid and octahydro-3a-methyl-2H-inden-2-one were identified tentatively as major compounds from the butanol fraction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.4
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• pp.516-523
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• 2015

This study investigated the antimutagenic and anticancer effects of Platycodon grandiflorum extract (PGE) and its fractions against carcinogenic N-nitrosodimethylamine (NDMA) and genotoxicity. The Ames Salmonella mutagenicity test employing histidine mutants of Salmonella Typhimurium TA98 and TA100 was used to examine the mutagenicity of PGE and its fractions. Bacterial reversion assay with S. Typhimurium TA98 and TA100 did not show a significantly increased number of revertant colonies. The same test was used to examine the ability of PGE and its fractions to prevent acquisition of N-methyl-N'-nitro-N-nitrosoguanidine- and 4-introquino-line-1-oxide-induced mutations. PGE and its fractions inhibited mutagenesis in a dose-dependent manner. Among the fractions, ethyl acetate fraction from PGE (PGEA) exhibited a higher antimutagenic effect than other fractions. PGE and its fractions suppressed the growth of cancer cell lines, including human cervical adenocarcinoma, human hepatocellular carcinoma, human breast adenocarcinoma, human lung carcinoma, and transformed primary human embryonic kidney cells. In addition, we evaluated the antitumor activity of PGEA and its fractions in sacorma-180 solid tumor-bearing mice. In vivo anticancer activity results showed that PGE and its fractions could more effectively suppress tumor growth than the control. PGEA showed higher in vitro and in vivo anticancer effects than PGE and other fractions, and PGEA inhibited NDMA formation. Thus, we showed that PGEA has antimutagenic and anticancer activities, making it a candidate anticancer material under these experimental conditions.