Cathode materials of Li ion battery

심영재,문성인,형유업,도칠훈,윤문수 국립경상대학교 공과대학 부설 첨단소재연구소 1994 尖端素材 Vol.4 No.-

Li ion 2차전지는 높은 전지전압, 낮은 자기방전율, High Energy Density High Power Density Non-Toxic, No Memory Effect등의 우수한 특성을 보유하고 있고, 환경적인 측면에서 Lead Acid 전지 및 Ni/Cd 전지 등과 같은 Pb, Cd 및 Hg 등으로 인한 환경오염문제가 없는 고성능 신형전지로써, 92년에 SONY사에서 최초의 시제품을 내놓은 이래 현재 소형녹음기, 캠코더 및 셀룰라폰용으로 시판되고 있으나 세계적으로 Li ion 전지를 생산할 수 있는 회사는 일본의 몇몇 기업으로 한정되어 있는 실정이다.

참죽나무(Cedrela sinensis Juss)의 培養細胞로 부터 體細胞胚 形成과 人工種子 生産

蘇雄永,呂邑東,蘇祥燮 全北大學校 基礎科學硏究所 1991 基礎科學 Vol.14 No.2

참죽나무의 배양세포를 물리 및 화학적인 복합방법으로 동조화를 거쳐 균일한 체세포배형성을 시도하였던바 85%의 높은 향상율을 보였다. 이에 다시 몇가지 아미노산, ABA 및 저온처리를 하여 얻은 정상적인 체세포배를 인공종자로 만들었다. 아미노산 중에서 aspartic acid 및 asparagine의 처리는 정상체세포배형성에 효과적이었는데 인공종자발아에는 별로 성과를 나타내지 않았다. ABA 및 저온처리로 정상체세포배형성율을 향상시킬 수 있었으나 인공종자의 발아에는 저온처리를 한 경우가 더욱 효과적이었다. 그러므로 간단하게 저온처리를 하여 경화된 건실한 체세포배 및 인공종자를 얻을 수 있고 이로 부터 클론식물의 대량생산이 가능할 것으로 사료된다. Somatic embryogenesis in cell suspension cultures of Cedrela sinensis Juss. was synchronized by physical and chemical treatments. Using culture medium containing aspartic acid and asparagine of 5mM each, the quality of somatic embryo from synchronized cell clumps was enhanced, but it was not effective for artificial seed germination. Somatic embryos were singly encapsulated with alginic acid to be used as an artificial seed. To improve the germination rate of artificial seeds, somatic embryos were hardened by ABA and low temperature(4℃) treatments before encapsulation. Low temperature treatment was more effective than ABA treatment.

침식된 유치 법랑질에 대한 레이저 조사 및 불소도포의 재광화 효과

양영숙,이광희,,김대업,라지영 大韓小兒齒科學會 2006 大韓小兒齒科學會誌 Vol.33 No.2

연구목적은 산성 음료수에 의해 탈회된 법랑질의 표면에 대한 Nd:YAG 레이저 조사의 재광화 효과와 불화물 도표의 효과를 평가하는 것이다. 치아우식증, 색소, 손상, 부착물이 없는 건전한 사람의 유치의 평활면으로부터 법랑질 시편을 제작하고, 코카콜라에 12시간 동안 담가 탈회시켰다. 탈회된 법랑질 표면에 6 W 출력, 50 mJ, 20 Hz pulse rate 의 에너지 밀도로 Nd:YAG 레이저를 조사하였다. 탈회 전후와 레이저 조사 후에 미세경도 및 Diagnodent 점수를 측정한 후, 0.05% 불소 용액, 1.23% 불소 젤, 0.1% 불소 바니쉬 중의 한 가지를 도포하였으며 미세경도 및 Diagnodent 측정을 통하여 레이저의 재광화 효과와 불소의 효과를 평가하였다. 1. Diagnodent 측정치의 변화에서, 탈회 후에는 초기 점수의 23.51%로 감소하였고, 레이저 조사 후에는 초기 점수의 37.37%로 증가하였으며, 불소도포 후에는 초기 점수의 51.34%로 증가하였고, 전체적으로 보면 초기 점수, 탈회 후 점수, 레이저 조사 후의 점수, 불소도포 후의 점수 및 그 백분율 사이에 모두 유의한 차이가 있었다(p<0.05). 3개 불소군 사이의 차이는 초기점수 및 불소도포 후 점수와 백분율에서 모두 유의하지 않았으며, 각 불소군 내에서는 불소 용액군과 불소 바니쉬군에서 초기 점수, 탈회후 점수, 레이저 조사 후의 점수, 불소도포 후의 점수 및 그 백분율사이에 모두 유의한 차이가 있었고, 불소 젤군에서는 레이저 조사 후와 불소도포 후의 점수 및 백분율 사이에 유의한 차이가 없었다. 2. 미세경도의 변화에서, 탈회 후의 경도는 초기 경도의 33.58%로 감소하였고, 레이저 조사 후의 경도는 초기 경도의 43.99%로 증가하였으며, 불소도포 후의 경도는 초기 경도의 51.38%로 증가하였고, 전체적으로 보면 초기 경도, 탈회후 경도, 레이저 조사후의 경도, 불소도포 후의 경도 및 그 백분율 사이에 모두 유의한 차이가 있었다(P<0.05). 불소군 별로 보면 3개 불소군 사이의 차이는 모두 유의하지 않았고, 백분율에서도 초기경도와 불소도포 후 경도에서 유의하지 않았으며, 각 불소군 내에서는 초기 경도, 탈회 후 경도, 레이저 조사 후의 경도, 불소도포 후의 경도 및 백분율 사이에 모두 유의한 차이가 있었다. The purpose of this in vitro study was to evaluate the remineralizing effects of Nd:YAG laser irradiation and fluorides application on primary tooth enamel eroded by acidic drink. The materials were 30 sound primary teeth with intact smooth enamel surfaces. They were demineralized with Coca-cola at 37℃ for 12 hours and then irradiated by Nd:YAG laser with 6W power, 50mJ/㎠ energy density, and 20 Hz pulse repetition. After laser irradiation. teeth were treated by three kinds of fluorides: (1) 0.05% NaF solution, (2) 1.23% APF gel and (3) 0.1% fluoride varnish. Diagnodent scores and microhardness (VHN) were measured before and after the each treatment. The results were as follows: 1. Diagnodent scores decreased to 23.51% from the initial after demineralization, and then increased to 37.37% after laser irradiation, and to 51.34% after fluoride treatment. There were significant differences between the total scores of initial, demineralization, laser irradiation and fluoride treatment(P<0.05). There was no significant difference between scores after fluoride treatment according to fluoride types. 2. Microhardness(VHN) decreased to 33.58% from the initial after demineralization, and then increased to 43.99% after laser irradiation, and to 51.38% after fluoride treatment. There were significant differences between the total scores of initial, demineralization, laser irradiation and fluoride treatment (P<0.05). There was no significant difference between scores after fluoride treatment according to fluoride types.

구연산과 칼슘이 치아침식증의 발생에 미치는 영향

송인경,이광희,김대업,양영숙 大韓小兒齒科學會 2005 大韓小兒齒科學會誌 Vol.32 No.3

산성 음료의 치아침식증 유발력을 감소시키기 위한 연구의 일환으로, 0.1%, 0.3%, 0.5%, 1.0% 구연산용백의 5분, 15분, 30분, 60분간의 사람 소구치 법랑질의 치아침식증 유발력 및 구연산용액에 첨가되는 칼슘 0.05%, 0.1%, 0.2%에 따른 치아침식증 발생 억제효과를 표면미세경도를 측정하여 연구하였다. 전체적으로 볼 때, 구연산 농도가 높을수륵, 탈회시간이 길수록, 칼슘농도가 낮을수록 탈회후 경도가 하락하였다. 탈회 5분 후 경도는 칼슘 무첨가의 경우에 76~90%이었고 칼슘 첨가에 따른 5분간의 탈회억제량은 2~l5%이었다. 탈회 15분 후 경도는 칼슘 무첨가의 경우에 65~84%이었고 칼슘 첨가에 따른 15분간의 탈회억제량은 3~l7%이었다. 탈회 30분 후 경도는 칼슘 무첨가의 경우에 53~72%이었고 칼슘 첨가에 따른 30분간의 탈회억제랑은 6~22%이었다. 탈회 60분 후 경도는 칼슘 무첨가의 경우에 43~66%이었고 칼슘 첨가에 따른 60분간의 탈회억제량은 7~l9%이었다. 탈회억제량의 분포를 전체적으로 보면, 구연산 농도에서는 1.0%에서 가장 크게 나타났고, 칼슘농도에서는 0.2%에서 가장 크게 나타났으며, 탈회시간에서는 0,1% 구연산용액에서는 탈회시간이 증가함과 더불어 탈회억제량도 함께 커지는 경향을 보였으나, 0.3% 이상의 구연산용액에서는 30분에 가장 크고 60분에 약간 감소하는 경향을 보였다 이상의 결과는 구연산에 의한 치아침식증 발생에 칼슘이 억제효과를 나타낼 수 있음을 시사한다. The purpose of study was to observe the effect of calcium and citric acid on the dental erosion of human premolar enamel. Enamel specimens were demineralized in 0.1%, 0.3%, 0.5%, or 1.0% citric acid solutions with 0.05%, 0.1%, or 0.2% calcium for 5, 15, 30, and 60 minutes, and then the surface microhardness of the enamel was measured. The hardness decreased as the concentration of citric acid and the demineralization time increased. Hardness after 5 minutes was 76~90% in case of no calcium and the inhibition of dental erosion by calcium addition was 2~15%. Hardness after 15 minutes was 65~84% in case of no calcium and the inhibition of dental erosion by calcium addition was 3~17%. Hardness after 30 minutes was 53~72% in case of no calcium and the inhibition of dental erosion by calcium addition was 6~22%. Hardness after 60 minutes was 43~66% in case of no calcium and the inhibition of dental erosion by calcium addition was 7~19%. The inhibition was the highest in 1.0% citric acid and 0.2% calcium. In 0.1% citric acid the inhibition increased as the demineralization time increased, but in 0.3% to 1.0% citric acid the inhibition was most high at 30 minutes and decreased a little at 60 minutes. These results suggest that calcium has a inhibitory effect on the citric acid induced dental erosion.

Synthesis and Color Tuning of Poly(p-phenylenevinylene) Containing Terphenyl Units for Light Emitting Diodes

Jin, Young-Eup,Kim, Jin-Woo,Park, Sung-Heum,Kim, Hee-Joo,Lee, Kwang-Hee,Suh, Hong-Suk Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.11

New PPV based conjugated polymers, containing terphenyl units, were prepared as the electroluminescent (EL) layer in light-emitting diodes (LEDs). The prepared polymers, poly[2,5-bis(4-(2-etylhexyloxy)phenyl)-1,4-phenylenevinylene] (BEHP-PPV), poly[2-(2-ethylhexyloxy)-5-(4-(4-(2-etylhexyloxy)phenyl)phenyl)-1,4-phenylenevinylene] (EEPP-PPV) and poly[2-(2-ethylhexyloxy)-5-(9,9-bis(2-etylhexyl)fluorenyl)-1,4 phenylenevinylene] (EHF-PPV), were soluble in common organic solvents and used as the EL layer in double layer light-emitting diodes (LEDs) (ITO/PEDOT/polymer/Al). The polymers were prepared by the Gilch reaction. The number-average molecular weight $(M_n)$, weight-average molecular weight $(M_w)$, and the polydispersities (PDI) of these polymers were in the range of 9000-58000, 27000-231000, 2.9-3.9, respectively. These polymers have quite good thermal stability with decomposition starting above 320-350. The polymers show photoluminescence (PL) with maximum peaks at around 526-562 nm (exciting wavelength, 410 nm) and blue EL with maximum peaks at around $\lambda_{max}$ = 526-552 nm. The current-voltageluminance (I-V-L) characteristics of polymers show turn-on voltages of 5 V. Even though both of EEPP-PPV and BEHP-PPV have the same terphenyl group in the repeating unit, EEPP-PPV with directly substituted alkoxy group in the back bone has longer effective conjugation length than BEHP-PPV, and exhibits red shift in the PL spectra. Both of EEPP-PPV and EHF-PPV have ter-phenyl units and directly substituted alkoxy group in back bone. EHF-PPV with fluorenyl unit attached to the PPV backbone has shorter effective conjugation length than EEPP-PPV with biphenyl unit, and exhibits blue shift in the PL spectra.

Life Cycle and Host Specificity of Tanysphyrus (Tanysphyroides) major Roelofs (Coleoptera:Curculionidae), a Possible Candidate Agent for the Biological Control of Monochoria vaginalis var. plantaginea

Jin Young Park(박진영),Jae Eup Park(박재읍),In Young Lee(이인용),Oh Seok Kwon(권오석),Jong Kyun Park(박종균) 韓國雜草學會 2011 Weed&Turfgrass Science Vol.31 No.1

물달개비는 한국의 논에서 문제되는 난방제 잡초중의 하나이다. 물달개비의 생물학적 방제 인자로 물달개비바구미를 선발하였다. 생물학적 방제에 이용하기 위해 2006년과 2007년 계대사육을 실시하여 형태적, 생태적 특징을 조사하였다. 이 종은 1년에 한세대만 경과하며 성충으로 월동하고, 성충은 6월 하순부터 9월 하순까지 발생한다. 물달개비바구미는 알에서 성충까지 22±0.7일이 소요된다. 주요 농작물과 수생식물 60종을 대상으로 기주특이성을 조사 결과 물달개비의 생물학적 방제 곤충으로서의 가능성을 보였다. Monochoria vaginalis var. plantaginea (Pontederiaceae) is one of the most problematic weed in the rice field in Korea. Tanysphyrus (Tanysphyroides) major was selected as a potential biological control agent for M. vaginalis. Continuous rearing of T. (T.) major was carried out from 2006 to 2007, and its morphological characteristics and ecological characteristics were investigated. This species has a single generation per year, over-wintering as an adult stage. The emergence of adults starts in later June and last until September. These observations indicate that T. (T.) major takes 22±0.7 days to develop from egg to adulthood. Host specificity test showed that finally selected this species was suitable candidates for the biological control of M. vaginalis var. plantaginea since it showed negative host specificity against major 60 test crops.

Polymer Light-Emitting Diodes Based on PPDFV Copolymers with Fluoro Groups in Vinylene Units

Jin, Young-Eup,Kim, Jin-Woo,Song, Su-Hee,Park, Sung-Heum,Lee, Kwang-Hee,Suh, Hong-Suk Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.5

Novel Poly(p-phenylenevinylene)s Derivatives with CF₃-Phenyl Substituent for Light-Emitting Diodes

Jin, Young-Eup,Kim, Jin-Woo,Park, Sung-Heum,Lee, Kwang-Hee,Suh, Hong-Suk Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.5

New PPV derivatives which contain electron-withdrawing trifluoromethyl ($CF_3$) group, poly[2-(2-ethylhexyloxy)-5-(4-trifluoro methylphenyl)-1,4-phenylenevinylene] (EH$CF_3$P-PPV), and poly[2-(2-ethylhexyloxy)-5-(3,5-bis(trifluoromethyl)-phenyl)-1,4-phenylenevinylene] (EHB$CF_3$P-PPV), have been synthesized by GILCH polymerization. As the result of the introduction of the electron-withdrawing $CF_3$ group to the phenyl substituent, the LUMO and HOMO energy levels of EH$CF_3$P-PPV (2.8, 5.1 eV) and EHB$CF_3$P-PPV (3.0, 5.3 eV) were lower than those of known poly[2-(2-ethylhexyloxy)-5-phenyl-1,4-phenylenevinylene] (EHP-PPV) (2.6, 4.9 eV). These polymers have been used as the electroluminescent (EL) layers in double layer lightemitting diodes (LEDs) (ITO/PEDOT/polymer/Al). EH$CF_3$P-PPV, and EHB$CF_3$P-PPV show maximum photoluminescence (PL) peaks at ${\lambda}_{max}$ = 550, 539 nm, and maximum EL peak at ${\lambda}_{max}$ = 545, 540 nm, respectively. The current-voltage-luminance (I-V-L) characteristics of the polymers show that turn-on voltages of EH$CF_3$P-PPV and EHB$CF_3$P-PPV are around 4.0 and 3.5 V, respectively.

Synthesis and Properties of PCPP-Based Conjugated Polymers Containing Pendant Carbazole Units for LEDs

Jin, Young-Eup,Kim, Sun-Hee,Lee, Hyo-Jin,Song, Su-Hee,Kim, Yun-Na,Woo, Han-Young,Lee, Kwang-Hee,Suh, Hong-Suk Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.12

New poly(cyclopenta[def]phenanthrene) (PCPP)-based conjugated copolymers, containing carbazole units as pendants, were prepared as the electroluminescent (EL) layer in light-emitting diodes (LEDs) to show that most of them have higher maximum brightness and EL efficiency. The prepared polymers, Poly(2,6-(4-(6-(Ncarbazolyl)- hexyl)-4-octyl-4H-cyclopenta[def]phenanthrene)) (CzPCPP10) and Poly(2,6-(4-(6-(N-carbazolyl)- hexyl)-4-octyl-4H-cyclopenta[def]phenanthrene))-co-(2,6-(4,4-dioctyl-4H-cyclopenta[def]phenanthrene)) (CzPCPP7 and CzPCPP5), were soluble in common organic solvents and used as the EL layer in light-emitting diodes (LEDs) of configuration with ITO/PEDOT/polymer/Ca/Al device. The polymers are thermally stable with glass transition temperature (Tg) at 77-100 °C and decomposition temperature (Td) at 423-457 °C. The studies of cyclic voltammetry indicated same HOME levels in all polymers, although the ratios of carbazole units are different. In case of PLEDs with configuration of ITO/PEDOT/CzPCPPs/Ca/Al device, The EL maximum peaks were around 450 nm, which the turn-on voltages were about 6.0-6.5 V. The maximum luminescence of PLEDs using CzPCPP10 was over 4400 cd/m2 at 6.5 V, which all of the maximum EL efficiency were 0.12 cd/A. The CIE coordinates of the EL spectrum of PLEDs using CzPCPP10 was (0.18, 0.08), which are quite close to that of the standard blue (0.14, 0.08) of NTSC.

Poly(p-phenylenevinylene)s Derivatives Containing a New Electron-Withdrawing CF₃F₄Phenyl Group for LEDs

Jin, Young-Eup,Kang, Jeung-Hee,Song, Su-Hee,Park, Sung-Heum,Moon, Ji-Hyun,Woo, Han-Young,Lee, Kwang-Hee,Suh, Hong-Suk Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.1

New PPV derivatives which contain electron-withdrawing CF3F4phenyl group, poly[2-(2-ethylhexyloxy)-5-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)-1,4-phenylenevinylene] (CF3F4P-PPV), and poly[2-(4-(2-etylhexyloxy)-phenyl)-5-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)-1,4-phenylenevinylene] (P-CF3F4P-PPV), have been synthesized by GILCH polymerization. As the result of the introduction of the electron-withdrawing CF3F4phenyl group to the phenyl backbone, the LUMO and HOMO energy levels of CF3F4P-PPV (3.14, 5.50 eV) and P-CF3F4P-PPV (3.07, 5.60 eV) were reduced. The PL emission spectra in solid thin film are more red-shifted over 50 nm and increased fwhm (full width at half maximum) than solution conditions by raising aggregation among polymer backbone due to electron withdrawing effect of 2,3,5,6-tetrafluoro-4-trifluoromethylphenyl group. The EL emission maxima of CF3F4P-PPV and P-CF3F4P-PPV appear at around 530-543 nm. The current density-voltage-luminescence (J-V-L) characteristics of ITO/PEDOT/polymer/Al devices of CF3F4P-PPV and P-CF3F4P-PPV show that turn-on voltages are around 12.5 and 7.0 V, and the maximum brightness are about 82 and 598 cd/m2, respectively. The maximum EL efficiency of P-CF3F4P-PPV (0.51 cd/A) was higher than that of CF3F4P-PPV (0.025 cd/A).