• Journal of the Korean Ceramic Society
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• v.45 no.3
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• pp.167-171
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• 2008

Zirconium-doped $Li_{1.1}Co_{1-x}Zr_xO_2(0{\leq}x{\leq}0.05)$ powders as cathode materials for lithium ion batteries were synthesized using an ultrasonic spray pyrolysis method. Cyclic voltammetry and cyclic stability tests were performed, and the changes of microstructure were observed. The solubility limit of zirconium into $Li_{1.1}CoO_2$ was less than 5 mol%, and monoclinic $Li_2ZrO_3$ phase was formed above the limit. The Zr-doping suppressed the grain growth and increased the lattice parameters of the hexagonal $LiCoO_2$ phase. The Zr-dopiong of 1mol% resulted in the best cyclic performance in the range of $3.0{\sim}4.3V$ at 1C rate (140 mA/g); the initial discharge capacity decreased from 158 mAh/g to 60 mAh/g in the undoped powder, while from 154 mAh/g to 135 mAh/g in the Zr-doped powder of 1 mol% after 30 cycles. The excellent cycle stability of Zr-doped powder was due to the low polarization during chargedischarge processes which resulted from the delayed collapse of the crystal structure of the active materials with Zr-doping.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.1
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• pp.22-29
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• 2006

We demonstrate highly manufacturable Multi-channel Field Effect Transistor (McFET) on bulk Si wafer. McFET shows excellent transistor characteristics, such as $5{\sim}6 times higher drive current than planar MOSFET, ideal subthreshold swing, low drain induced barrier lowering (DIBL) without pocket implantation and negligible body bias dependency, maintaining the same source/drain resistance as that of a planar transistor due to the unique feature of McFET. And suitable threshold voltage ($V_T$) for SRAM operation and high static noise margin (SNM) are achieved by using TiN metal gate electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.55-56
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• 2009

Small RFID tag antenna were fabricated on Si substrate and their physical and electrical properties were evaluated. With decreasing the size of tag antenna on Si substrate, small SMD-type RFID tags could be fabricated, which is very useful for PCB tracking. Firstly, tag antenna pattern and the electromagnetic properties were simulated with HFSS. The frequency was 13.56MHz, the line-width and line-gap were modeled in the range of $50{\sim}200{\mu}m$. S parameters, SRF, and Q value were calculated from geometry. When the line-width and line-gap were 100um and the loop-turn was 10, the SRF was 80MHZ and the Q value was ca. 9. When the microstrip antenna pattern of aluminum was fabricated by using DC sputtering, Vpp of ca. 1.6V was obtained when the reader-tag distance was 40mm.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3281-3287
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• 2016

Bioactive compounds extracted from leaves and twigs of Goniothalamus griffithii include pinocembrin (PCN) and goniothalamin (GTN). The objectives of this study were to investigate the cytotoxic activities of PCN and GTN and their influence on molecular signaling for cell death in several human cancer cell lines compared to normal murine fibroblast NIH3T3 cells. GTN exhibited the most potent cytotoxicity against MCF-7 > HeLa > HepG2 > NIH3T3 cells with $IC_{50}$ values of 7.33, 14.8, 37.1 and $65.4{\mu}M$, respectively, whereas PCN was cytotoxic only to HepG2 cells with $IC_{50}$ values of ${\sim}80{\mu}M$. Apoptotic cell death was confirmed by staining the cells with annexin V-FITC and propidium iodide (PI) employing flow cytometry. Apoptosis was shown by externalization of phosphatidylserine in goniothalamin-treated MCF-7 cells in a dose response manner. Positive PI-stained cells with the typical morphology of apoptotic cells were increased dose-dependently. Furthermore, reduction of mitochondrial transmembrane potential was found in goniothalamin-treated MCF-7, HepG2 and HeLa cells. GTN treatment in MCF-7 increased caspase-3, -8 and -9 activities while GTN-induced HeLa cells showed an increase of both caspase-3 and -9 activities. But an increased caspase-8 activity was demonstrated in GTN- and PCN-treated MCF-7 and HepG2 cells, respectively. Taken together, GTN- and PCN-induced human cancer cell apoptosis was through different molecular mechanisms or signaling pathways, which might be due to different machineries in different types of cancer cells, as evidenced by the compound-modulated caspase activities in both intrinsic and/or extrinsic pathways.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.1
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• pp.39-51
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• 2012

Aerosol slurry samples were collected in 60-min interval using Korean Semi-continuous Elements in Aerosol Sampler (KSEAS) between May 19 and June 6, 2010 at an urban site of Gwangju. The $PM_{2.5}$ samples were collected with a flow rate of 16.7 L/min and particles are grown by condensation of water vapor in a condenser maintained at ${\sim}5^{\circ}C$ after saturation by direct injection of steam. The resulting droplets are collected in a liquid slurry with a airdroplet separator. Concentrations of 16 elements (Al, Fe, Mn, Ca, K, Cu, Zn, Pb, Cd, Cr, Ti, V, Ni, Co, As, Se) in the collected slurry samples were determined off-line by ICP-MS. KSEAS sample analysis encompassed the sampling periods for which 24-hr average elemental species concentrations were calculated for comparison with those derived from 24-hr integrated filter samples. Relationship between elemental species measured by two methods indicated high correlation coefficients (r), mostly greater than r of 0.80. However, we note that concentrations of Al, K, Ca, Mn, and Fe, which are often associated with crustal elemental particles, in the KSEAS samples, were substantially lower (1.4~11 times) than those found in the typical filter-based samples. This discrepancy is probably due to difficulties in transferring insoluble dust particles to the collection vials in the KSEAS. Temporal profiles of elemental concentrations indicate that some transient events in their concentrations are observed over the sampling periods. For the elemental species studied, atmospheric concentrations during the transient events increased by factors of 4 in Mn~80 in Zn, compared to their background levels. Principle component analyses were applied to the hourly KSEAS data sets to identify sources affecting the concentrations of the metal constituents observed. In this study, we conclude that hourly measurements for particle-bound elemental constituents were extremely useful for revealing the short-term variability in their concentrations and developing insights into their sources.

• Korean Journal of Human Ecology
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• v.18 no.6
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• pp.1315-1321
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• 2009

The chemical composition of natural powder dye $Pinux^{TM}$ manufactured from Pinus radiata bark and dyeability of dyed silk fabrics with $Pinux^{TM}$ were examined. It is made up of the optimum dyeing condition of silk fabric according to the dyeing concentration, dyeing time, and dyeing temperature. Also, we examined the colorfastness and antibiosis of dyed silk fabrics to washing, rubbing, perspiration and light. For the analysis of the chemical composition of $Pinux^{TM}$, the total contents of phenolic compound, proanthocyanidin(PA) and anti-oxidative activities of the dye were analyzed. As a result, it was found that the main components of the $Pinux^{TM}$ manufactured from Pinus radiata bark is proanthocyanidin, mostly a flavonoid containing a procyanidin structure, and it consists of approximately 63% phenol. As a result of examining the dyeability of silk fabrics with $Pinux^{TM}$, it showed that the dyeability was best under the conditions of the concentration of dye $1{\sim}1.5%$(wt/v%), dyeing time of 90 minutes, and dyeing temperature at $90^{\circ}C$. It was found that the colorfastness of dyed silk fabrics, colorfastness to washing, perspiration for acidic and rubbing were as good as grade 4 or 4-5. However, the colorfastness to light was low at grade 1, the same as the results of other natural dyed fabrics. As a result of the antibiosis measurement for the $Pinux^{TM}$-dyed silk fabrics, it showed high antibacterial properties to Staphylococcus sureus at 99.6%.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.52-52
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• 2010

본 연구에서 우리는 HPHT 처리 전 FT-IR spectrometer를 이용한 사전분석을 통해 type Ia brown 다이아몬드를 IaA, IaB, IaAB (A>B), IaAB (A=B), IaAB (A$1700-1800^{\circ}C$, 5 GPa에서 다이아몬드가 흑연화 되지 않는 범위 하에 HPHT처리를 시행하였다. 자외선-가시광선 분광분석기(UV-Vis Spectrometer, Shimadzu UV 3101PC)를 사용하여 350~800 nm에서의 가시광선 범위를 0.1nm의 분해능으로 투과(Transmittance) 모드로 측정하였고, 퓨리에 변환 적외선 분광분석기(FT-IR spectrometer, Jasco-4100)을 사용하여 $400{\sim}6000cm^{-1}$의 범위에서 $4cm^{-1}$ 의 분해능으로 흡수(Absorption) 모드로 측정한 후 HPHT 처리 전후를 비교 분석하였다. 또한 광루미네선스(Photoluminescence) 분석은 325 nm He-Cd laser를 광원으로 한(PL, Spectra-pro 2150i, Spectra-pro 2300i micro-spectrometer) 및 532 nm green laser를 광원으로 한(PL, SAS 2000)를 사용하여 각각 350~600 nm, 550~1100 nm의 범위에서 0.1nm step으로 측정하여 HPHT 처리전과 후를 비교 분석하였다. HPHT처리 후 모든 시료는 N3 center (415.4 nm), H4 center (496.4nm) 및 platelet와 연관된 ($1363\;cm^{-1}$)의 peak가 감소하였고, H3 center (503.2 nm)와 G-band가 증가하는 경향을 나타내었다. 또한 HPHT 처리 시 질소의 B집합보다 A집합이 더 감소하는 경향을 나타내었으며, A 또는 B집합의 파괴에서 발생된 질소 원자에 의해 질소의 interstitial center (594 nm)가 증가함을 알 수 있었다. HPHT 처리 후 모든 시료는 (N-V)- center가 생성됨을 확인 할 수 있었다. 결론적으로 본 연구를 통해 HPHT 처리를 통해 다이아몬드 내에 존재하는 질소결합관련 상태의 변화를 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.312.1-312.1
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• 2014

Chalcopyrite계 화합물 반도체인 $Cu(InGa)Se_2$ (CIGS)는 직접천이형 에너지 밴드갭과 전파장 영역에 대하여 높은 광흡수계수($1{\times}$[10]^5/cm)를 가지므로 두께 $1{\sim}2{\mu}m$인 박막형태으로 고효율의 태양전지 제조가 가능하다. 또한, 박막공정의 저가 가능성을 나타내면서 전세계적으로 많은 연구와 관심을 받고 있고, 현재 상용화되어 있는 결정질실리콘 태양전지를 대체할만한 재료로 주목 받고 있다. 일반적으로, CIGS박막형 태양전지 구성은는 유리를 기판으로 하여 5개의 단위 박막인 Mo 후면전극, p형 반도체 CIGS 광흡수층, n형 반도체 CdS 버퍼층, doped-ZnO 상부 투명전극, $MgF_2$ 반사방지막으로 이루어진다. 이들 중에서 태양전지의 에너지 변환효율에 결정적인 영향을 미치는 구성된다. CIGS 광흡수층의 제조는 크게 진공법과 비진공방법으로 나뉜다. 현재까지 보고된 문헌에 따르면 CIGS 박막형 태양전지의 경우에 동시증발법으로 20.3%의 에너지 변환효율을 보였지만,는데, 이는 진공장비 특성상 공정단가가 높고 대면적화가 어렵다는 단점을 가진다. 따라서, 비진공법을 이용하여 광흡수층 제작하는 것이 기술적으로 진보할 여지가 크다고 볼 수 있다. 반면 현재 상용화되어 있는 결정질실리콘 태양전지를 대체할만한 방법으로 주목 받고 있는 비진공을 이용한 저가공정은 최근 15.5%의 에너지 변환효율이 보고 되었다. 비진공법에는 전계를 이용한 증착법 및 스프레이법으로 나뉘며, 이들 광흡수층 재료의 화학적 합성은 III족 원소인 In, Ga의 함량비에 따라 광흡수층의 에너지 밴드갭(1.04~1.5 eV) 조절이 가능하다. 따라서, 본 연구에서는 비진공법에 사용되는 CIGS재료의 화학적 합성조건을 변화시켜 III족 원소의 조성비 조절을 시도하였다. CIGS 분말 시료의 입자 형태와 크기를 FE-SEM을 이용하여 관찰하였고, 화합물의 성분비를 EDX 및 XRD 분석을 통해 Ga 함량에 따른 구조적 차이를 비교해 보았다.

• The Korean Journal of Mycology
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• v.21 no.1
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• pp.9-15
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• 1993

ABSTRACT: The cell fusants were constructed from complementary auxotrophic mutants of Phffia rhodozyma. The nuclear fusion of the fusants was demonstrated by several techniques including comparision of cell volume, estimation of DNA content and nuclear staining. The cell fusants were very stable for succeeding transfer culture on complex medium for more than one year. Malt extract (1%, w/v) and abscisic acid(1 mM) increased the carotenoid formation whereas gibberellic acid(5mM) and riboflavin(0.1 mM) decreased the corresponding content.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.170-176
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• 2009

Culture-independent 16S rDNA-DGGE profiling and phylogenetic analysis were used to examine the predominant bacterial communities associated with the two sponges, Dictyonella sp. and Spirastrella abata from Jeju island. The culture-independent approach involved extraction of total bacterial DNA, PCR amplification of the 16S ribosomal DNA using primer pair 341f-GC and 518r, and separation of the amplicons on a denaturing gradient gel. Denaturing gradient gel electrophoresis banding patterns indicated 8 and 7 bands from the two sponge species, Dictyonella sp. and Spirastrella abata, respectively. There were not common major bands in two different sponges. Comparative sequence analysis of variable DGGE bands revealed from 93% to 98% similarity to the known published sequences. The dominant bacterial group of Dictyonella sp. belonged to uncultured Gammaproteobacteria, while, that of Spirastrella abata belonged to uncultured Alphaproeobacteria and Firmicutes. DGGE analysis indicated predominant communities of the sponge-associated bacteria differ in the two sponges from the same geographical location. This result revealed that bacterial community profiles of the sponges were host species-specific.