• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1999년도 PROCEEDINGS OF 99 INTERNATIONAL CONFERENCE OF THE KACG AND 6TH KOREA·JAPAN EMG SYMPOSIUM (ELECTRONIC MATERIALS GROWTH SYMPOSIUM), HANYANG UNIVERSITY, SEOUL, 06월 09일 JUNE 1999
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• pp.371-387
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• 1999

La2-xSrxCuO4 single-crystalline films were prepared on bulk single crystals of Zn-doped La2CuO4 as the substrates by LPE technique using tow deferent methods. When prepared using an alumina crucible in normal electrical furnace, the La2-xSrxCuO4 films were contaminated with less than 3 at% aluminum from the alumina crucibles. Aluminum contamination either reduced or completely destroyed the superconductivity of the La2-xSrxCuO4 films. For LPE growthby modified TSFZ method using an infrared heating furnace without crucibles, the La2-xSrxCuO4 films of x=0.11 showed superconducting with Tconset 36 K, which is 10 K higher than that in the La2-xSrxCuO4 bulk single crystals.

• 한국결정성장학회지
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• 제9권4호
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• pp.384-386
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• 1999

The distribution coefficients of Ni and Zn to the Cu site in $La_{2-x}Sr_{x}CuO_{4}$(LCO) were investigated to determine the suitable solvent composition ofr crystal growth of $La_{2}{Cu}_{1-x}{M}_{x}{O}_{4}$(M=NI, Zn)(LCMO), and were found to be 4.2 for NI and 0.66 for Zn, respectively. Single crystals of LCO, and LCMO of high homogeneity were grown by traveling solvent floating zone technique using suitable solvents. NO diamagnetic signals were observed for all substituted crystals. This fact suggests that crystals of LCO partially substituted by Ni or Zn are useful as substrate crystals.

• The Korean Journal of Ceramics
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• 제4권1호
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• pp.5-8
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• 1998

Flat belt(FB) type high pressure apparatus has been succesfully utilized in various high pressure experimental stations in Korea and Japan to conduct HPHT (high pressure and high temperature) diamond synthesis. Present paper discusses pressure calibration of FB apparatus at high temperature to establish P-T condition of diamond synthesis. We also present some examples of controling P-T condition through careful experimental set-up of the high pressure sample cells. Finally we discuss reproducibility of pressure and temperature condition of the HPHT diamond synthesis.

• The Korean Journal of Ceramics
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• 제6권2호
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• pp.172-176
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• 2000

Solid solutions of Ti$_{0.5}$Zr$_{0.5}$B$_2$were successfully synthesized and densified simultaneously from elemental reactants by the use of a field-activated, pressure-assisted synthesis method. The method involves the application of an electric current and mechanical pressure across reactant compacts to achieve combustion synthesis. Dense solid solutions with relative densities of up to 99% were produced and characterized by XRD, SEM, and EPMA methods. With a maximum measured temperature of 145$0^{\circ}C$ under a load of 86 MPa for 30 min, the desired dense solid solution wad synthesized.

• 한국세라믹학회지
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• 제30권8호
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• pp.685-693
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• 1993

Boron cabride was prepared from the mixture of metal boron and graphite powders in Argon atmosphere by Self-propagating High-temperature Synthesis Chemical furnace. The most excellent mechanical properties were in the case that Fe was added as a sintering agent before the synthesis of the B4C in the Chemical furnace. Sintered B4C-5wt% Fe specimen showed the relative density of 95%, of theoretical value, and 3-point-flexural strength of 380MPa.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1999년도 PROCEEDINGS OF 99 INTERNATIONAL CONFERENCE OF THE KACG AND 6TH KOREA·JAPAN EMG SYMPOSIUM (ELECTRONIC MATERIALS GROWTH SYMPOSIUM), HANYANG UNIVERSITY, SEOUL, 06월 09일 JUNE 1999
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• pp.389-402
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• 1999

Single crystal of Li2Cu1-xMxO4 (M=Ni, Zn) are promising as a substrate to realize superconducting electronic devices. The distribution coefficients of Ni and Zn to the Cu site in La2CuO4 (LCO) were estimated by the zone melting technique to grow high quality single crystals of La2Cu1-xMxO4(M=Ni, Zn). The distribution coefficient value of Ni was estimated to be 4.2 and that of Zn was estimated to be 0.66, respectively. Suitable solvent compositions were determined using these values to grow single crystals by he traveling floating zone (TSFZ) method. Single crystal of LCO, La2Cu1-xMxO4(M=Ni(x=0.01, 0.02, 0.03, 0.04), Zn(x=0.01, 0.02, 0.03) of high homogeneity were grown. The behaviors of the magnetization of these as-grown crystals do not indicate superconductivity except LCO. Ni or Zn substitution can make LCO non superconductor. This fact suggest that single crystals substituted by Ni or Zn are useful as substrate crystals.

• 한국결정성장학회지
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• 제9권3호
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• pp.299-302
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• 1999

$La_{2-x}Sr_{x}CuO_{4}$ single-crystalline films were prepared on bulk single crystals of Zn-doped $La_{2-x}Sr_{x}CuO_{4}$ as the substrates by LPE technique using two deferent methods. When prepared using an alumina crucible in normal electrical furnace, the $La_{2-x}Sr_{x}CuO_{4}$ films were contaminated with less than 3 at% aluminum from the alumina crucibles. Aluminum contamination either reduced or completely destroyed the superconductivity of the $La_{2-x}Sr_{x}CuO_{4}$ films, For LPE growth by modified TSFZ method using an infrared heating furnace without crucibles, the $La_{2-x}Sr_{x}CuO_{4}$ films of x=0.11 showed superconducting with $Tc_{onset}=36\;K$, which is 10 K higher than that in the $La_{2-x}Sr_{x}CuO_{4}$ bulk single crystals.

• Membrane and Water Treatment
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• 제10권5호
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• pp.353-360
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• 2019

ZSM-5 membrane was prepared on tubular macroporous ${\alpha}$-alumina support using a different synthesis route. The effects of organic template agent and Si/Al ratio of the synthesis gel on morphology, structure, and separation performance of the ZSM-5 membrane used for dehydration of isopropanol were investigated. High water perm-selectivity ZSM-5 membrane with a thickness of about $3.0{\mu}m$ and a low Si/Al ratio of 10.1 was successfully prepared from organotemplate-free synthesis gel with a molar composition of $SiO_2$ : $0.050Al_2O_3$ : $0.21Na_2O$ : NaF : $51.6H_2O$ at $175^{\circ}C$ for 24 h. The ZSM-5 membrane exhibited high pervaporation performance with a flux of $3.92kg/(m^2{\cdot}h)$ and corresponding separation factor of higher than 10,000 for dehydration of 90 wt.% isopropanol/water mixture at $75^{\circ}C$.

• 한국세라믹학회지
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• 제54권4호
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• pp.272-277
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• 2017

Organic-inorganic hybrid thermoelectric materials have obtained increasing attention because it opens the possibility of enhancing thermoelectric performance by utilizing the low thermal conductivity of organic thermoelectric materials and the high Seebeck coefficient of inorganic thermoelectric materials. Moreover, the organic-inorganic hybrid thermoelectric materials possess numerous advantages, including functional aspects such as flexibility or transparency, low cost raw materials, and simplified fabrication processes, thus, allowing for a wide range of potential applications. In this study, the types and synthesis methods of organic-inorganic thermoelectric hybrid materials were discussed along with the methods used to enhance their thermoelectric properties. As a key factor to maximize the thermoelectric performances of hybrid thermoelectric materials, the nanoengineering to control the nanostructure of the inorganic materials as well as the modification of the organic material structure and doping level are considered, respectively. Meanwhile, the interface between the inorganic and organic phase is also important to develop the hybrid thermoelectric module with excellent reliability and high thermoelectric efficiency in addition to its performance in various electronic devices.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3196-3202
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• 2012

Post-synthesis is used to synthesize organic hybrid inorganic mesoporous sieves. In this method, the activity and structure of the base sieve are crucial to obtain the definable hybrid materials. The chemical and physical properties of the base can be largely changed either by the final step of its synthesizing processes, by template removal which is accomplished with the oxidative thermal decomposition (burning) method or by solvent extraction method. In this paper we compared two methods for the post-synthesis of organic hybrid MCM-48. When the template was extracted with HCl/alcohol mixture, the final product showed larger pore size, larger pore volume and better crystallinity compared to the case of the thermal decomposition. The reactivity of the surface silanol group of template free MCM-48 was also checked with an alkylsilylation reagent $CH_2=CHSi(OC_2H_5)_3$. Raman and $^{29}Si$ NMR spectra of MCM-48 in the test reaction indicated that more of the organic group was grafted to the surface of the sample after the template was removed with the solvent extraction method. Direct synthesis of vinyl-MCM-48 was also investigated and its characteristics were compared with the case of post-synthesis. From the results, it was suggested that the structure and chemical reactivity can be maintained in the solvent extraction method and that organic grafting after the solvent extraction can be a good candidate to synthesize a definable hybrid porous material.