• Polymer(Korea)
• /
• v.25 no.4
• /
• pp.587-593
• /
• 2001

In this work, red mud (RM) was chemically modified by 0.1, 1, and 5 M H3PO4 solution to prepare epoxy/RM nanocomposites. The effect of chemical treatment on pH, acid-base values, specific surface area, and porosity of RM surface was analyzed. To estimate the mechanical interfacial properties of epoxy/RM nanocomposites, the critical stress intensity factor (K$_{IC}$) was measured. From the experimental results, it was clearly revealed that the porosity, specific surface area, and acid values of RM surface were developed as the increase of the treatment concentration due to the increase of acidic functional group, including hydroxyl group on RM surface. The mechanical interfacial properties of epoxy/treated-RM nanocomposites were higher than those of epoxy/RM as-received due to an improvement of interfacial bonding between basic matrix and RM surface.

• Journal of the Korean Magnetics Society
• /
• v.2 no.1
• /
• pp.15-21
• /
• 1992

Acicular ${\gamma}-Fe_{2}O_{3}$ particles were heated at $90^{\circ}C$ in alkaline solution containing mixed solution of dyadic metal with $Co^{+2}/Fe^{+2}$ ratio of 0.5. When cobalt content was increased, the coercivity of resultant product increased linearly, and surface area decreased. The cobalt ferrite was grown epitaxially on the surface ${\gamma}-Fe_{2}O_{3}$ crystal, and the increase of coercivity was attributed to the crystalline magnetic anisotropy of the cobalt ferrite which is conform to coating layer. We can expect superior magnetic properties above normal ratio of 2. The progress of reaction has an effect on coercivity of cobalt ferrite epitaxial iron oxide. The stability of temperature and the change om standin& of $Co-{\gamma}-Fe_{2}O_{3}$ was largely influenced by the composition of coating layer.

• Proceedings of the Korean Society for Bioinformatics Conference
• /
• 2006.02a
• /
• pp.116-123
• /
• 2006

생물체의 cDNA를 유리기판위에 고밀도로 첨착 시킨 유전자 칩과 정량적인 방법으로 개별 유전자 발현을 진단 가능한 Real- time PCR (실시간 고분자중합연쇄반응 기술) 기법은 첨단 의학분야와 신약개발 및 독성유전체 연구분야에 활발히 도입되고 있는 기술이다. 본 발표의 첫 번째 부분에서는 유전자칩 에서 얻어진 유전자 발현패턴분석에 기반한 바이오마커 선정 및 real time PCR에 의한 확증 관련 기술 과 유전자칩에서 얻어지는 수많은 데이터를 재정렬 및 다양한 분석기법과 display기술을 활용하여 광범위한 화학물질에 대한 독성효과 분석을 가능하게 해주며, 특정 독성물질에 대한 관련유전자 그룹 발견 및 독성영향에 따른 분류방법에 관한 결과를 발표할 것이다. 또한 바이오마커 활용의 하나로 박테리아세포 기반 바이오센서 제작및 세포칩 개발등에 대한 결과도 추가될 것이다. 두 번째 부분에서는 non-model organism(유전체정보가 확보되지 않은 생물체)인 송사리를 이용하여 새로운 2K 유전자칩을 개발하고, 여기서 각종 화학물질에 대하여 얻어진 수많은 유전자칩 분석 데이타를 활용하여 각각의 화학물질이 보여주는 독성효과를 매우 효과적이고 쉽게 이해할 수 있는 display기술을 개발, 적용함으로써 유전자칩 발현에 기반한 화학물질 독성 screening 및 specificity discrimination을 가능케 하는 예가 발표될 것이다. 이 연구에서 개발한 송사리 유전자칩은 간조직의 RNA를 직접 cDNA화 하는 방식을 취하고 있어 전체 송사리의 유전정보를 필요로 하지 않아 비용 및 효율에서 전체 송사리의 유전정보를 얻는 비용과 노력을 취하지 않고 간에서 발생하는 독성학적 영향 및 유전자의 발현정도를 정밀하고 효율적인 방법으로 얻어 낸다. 현재 2000여개의 cDNA유전자중 50%이상의 유전자가 17베타에스트라디올, 페놀, 노닐페놀, 비스페놀, 감마레이조사, 잔류약품중 이보프란, 다이클로펜악, 농약중의 파라???R, 돌연변이 유발물질 중의 이티비알, 금속류중의 카드뮴을 통해 발현양상과 특정 캐미칼별 발현 특이성이 조사되었고, 이들 유전자는 염기서열 분석을 통해 염기서열이 분석되었으며, 미국 NCBI의 유전자 은행과의 비교를 통해 일부유전자는 새로운 유전자로 밝혀지고 있다. 또한 이 발표에서는 소염진통제계열 의약품인 dichlofenac 이 송사리의 각종 조직에 미치는 독성영향을 Real-time PCR을 이용하여 대표적 스트레스 유전자의 발현에 미치는 영향에 대한 분석 예가 발표될 것이다.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.23 no.2
• /
• pp.81-85
• /
• 2013

We performed analysis of composition and structure of coating layers by using ED-XRF and TOF-SIMS for some passion topaz of Swarovski which developed recently as new surface treatment of TCF (thermal color fusion) technique. In addition, we compared differences between Ti-coated topaz (Mystic topaz) and new treated colored topazes (passion topaz) with magnification observation and simplified durability test. As a result, we can observe similar characteristic clues in Ti-coated topaz and passion topaz by magnified observation. According to results of depth profile by TOF-SIMS, we can know that topaz is treated by multi-layer coating or surface diffusion coating. Moreover, the passion topaz which is treated by chemical reaction between metal elements shows more stable chemical resistance and higher Mohs' hardness than Ti-coated topaz.

• Journal of the Korean Chemical Society
• /
• v.29 no.3
• /
• pp.257-264
• /
• 1985

Dioxobis(3-methoxysalicyaldehydato)molybdeum(VI) complex has been synthesized by reactions of 3-methoxysalicylaldehyde and ammonium paramolybdate in methanol solution. With appropriate primary amine, the resulting complex gave schiff-base complexes, MoO$_2$(CH$_3$O-sal-N-R)$_2$ in which C=O oxide ligands had been replaced by nitrogen. The properties and possible molecular structure of these complexes were discussed by elemental analysis, spectroscopic studies and electric conductivities measurements. It was found that the Mo(VI) complexes contain a cis-MoO$_2$ group since their infrared spectra two Mo=O band at about 900cm$^{-1}$ and the combining ratios for MoO$_2$-ligand are 1 : 2. Also, electronic spectra of molybdenyl complexes assigned to ligand-to-metal charge transfer transition. All of these complexes are yellow or orange, depolar compound and slightly soluble in alcohol, dichloromethane, chloroform and N,N-dimethylformamide.

• Journal of the Microelectronics and Packaging Society
• /
• v.6 no.2
• /
• pp.69-74
• /
• 1999

Graphite and carbonaceous materials intercalate and deintercalate Li-ion reversibly into their layered structures. These materials show an excellent capacity for using a negative electrode in Li-ion batteries, because the electrochemical potential of Li-ion intercalated carbon is almost identical with that of lithium metal. Carbon used in this study was obtained by the pyrolysis of petroleum pitch, and heat-treated at the several temperatures between $700^{\circ}C$ and $1300^{\circ}C$. XRD analysis revealed that crystallization of carbon increased with increasing the heat treatment temperature. Charge/discharge properties were studied by a constant-current step at the rate of 0.1C, and the interfacial reaction between the electrolyte and the surface of carbon electrode was studied by cyclic voltammetry. Cell capacities were investigated in terms of the heat treatment temperature and the cycle number. Reversible capacity increased with the heat treatment temperature up to $1000^{\circ}C$, thereafter decreased continuously. Also, charge capacity decreased with the cycle number, while the reversibility improved with it.

• Analytical Science and Technology
• /
• v.17 no.2
• /
• pp.91-97
• /
• 2004

Cryptand ion exchange resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene (DVB) copolymer with crosslink of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium ($UO{_2}^{2+}$) ion were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium ($UO{_2}^{2+}$), magnesium ($Mg^{2+}$), neodymium ($Nd^{3+}$) ion. The adsorption was in order of 1%, 2%, 5%, and 10% crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Polymer(Korea)
• /
• v.24 no.3
• /
• pp.382-388
• /
• 2000

Polymer electrolyte films consisting of poly(vinylidenefluoride-hexafluoropropylene) (PVdF-HFP), LiClO$_3$ and a mixture of ethylene carbonate (EC) and ${\gamma}$-butyrolactone (GBL) were examined in order to obtain the best compromise between high ionic conductivity, homogeniety, dimensional and electrochemical stability. Measurements of ionic conductivity, differential scanning calorimetry and linear sweep voltammetry have been carried out for various compositions. The highest conductivity of 3.8$\times$10$^{-3}$ S$cm^{-1}$ / at 3$0^{\circ}C$ were obtained for a film of 30(PVdF-HFP)+7.8LiClO$_4$+62.2EC/GBL. From the DSC study, it has been found that the PVdF-HFP gels are stable up to 10$0^{\circ}C$, and the salt lowers the melting temperature of crystalline part of PVdF by interacting sensitively with polymer segments. When Lithium metal is in contact with the gel films, it tends to undergo corrosion and the reaction products accumulate resulting in the formation of a passive film on Li electrode. As the aging time progresses, the interfacial resistance increases continuously. Anodic stability is measured to extend up to about 4.5 V vs. Li.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.129-129
• /
• 2010

적외선 검출소자(Infrared Photodetector)는 근적외선에서 원적외선 영역에 이르는 광범위한 파장 범위의 적외선을 이용하는 기기로서 대상물이 방사하는 적외선 영역의 에너지를 흡수하여 이를 영상화할 수 있는 장비이다. 적외선 관련 기술은 2차 세계대전 기간에 태동하였으며, 현재에는 원거리 감지기술 등과 접목되면서 그 활용 분야가 다양해지고 있다. 특히 능동형 정밀 타격무기를 비롯한 감시 정찰 장비 및 지능형 전투 장비 시스템 등에 대한 요구를 바탕으로 보다 정밀하고 신속한 표적 감지 및 정보처리 기술에 관한 연구가 선진국을 통해서 활발히 진행되고 있다. 기존의 Bolometer 형식의 열 감지 소자는 반응 속도가 느리고 측정 감도가 낮은 단점이 있으며, MCT(HgCdTe)를 이용한 적외선 검출기의 경우 높은 기계적 결함과 77K 저온에서 동작해야하기 때문에 발생하는 추가 비용 등이 문제점으로 지적되고 있다[1]. 이에 반해 화합물 반도체 자기조립 양자점(self-assembled quantum dot)을 이용한 적외선 수광소자는 양자점이 가지는 불연속적인 내부 에너지 준위로 인하여, 높은 내부 양자 효율과 온도 안정성을 기대할 수 있으며, 고성능, 고속처리, 저소비전력 및 저소음의 실현이 가능하다. 본 연구에서는 적층 InAs/InGaAs dot-in-a-well 구조를 유기금속화학기상증착법을 이용하여 성장하고 이를 소자에 응용하였다. 균일한 적층 양자점의 성장을 위해서 원자현미경(atomic force microscopy)을 이용하여, 각 층의 양자점의 크기와 밀도를 관찰하였고, photoluminescence (PL)를 이용하여 발광특성을 연구하였다. 각 층간의 GaAs space layer의 두께와 온도 조절 과정을 조절함으로써 균일한 적층 양자점 구조를 얻을 수 있었다. 이를 이용하여 양자점의 전도대 내부의 에너지 준위간 천이(intersubband transition)를 이용하는 n-type GaAs/intrinsic InAs 양자점/n-type GaAs 구조의 양자점 적외선수광소자 구조를 성장하였다. 이 과정에서 상부 n-type GaAs의 성장 온도가 600도 이상이 되는 경우 발광효율이 급격히 감소하고, 암전류가 크게 증가하는 것을 관찰하였다. 이는 InAs 양자점과 주변 GaAs 간의 열에 의한 상호 확산에 의하여 양자점의 전자 구속 효과를 저해하는 것으로 설명된다.

• Applied Chemistry for Engineering
• /
• v.19 no.3
• /
• pp.304-309
• /
• 2008

Cryptand series ion exchange resins were synthesized with 1-aza-12-crown-4 macrocyclic ligand attached to styrene (4 series dangerous matter) divinylbenzene (DVB) copolymer with crosslink of 1％, 2％, 4％ and 8％ by a substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, electron micrograph, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium (${UO_2}^{2+}$) ion were investigated. The uranium ion showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium (${UO_2}^{2+}$) > nickel ($Ni^{2+}$) > gadolinium ($Gd^{3+}$) ion. The adsorption was in order of 1％, 2％, 4％, and 8％ crosslinked resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.