• Elastomers and Composites
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• v.51 no.3
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• pp.195-205
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• 2016

A series of aromatic poly(hydroxyamide)s (PHAs) containing varying oligo(oxyethylene) substituents and 1,3-phenylene imide ring unit in the main chain were synthesized by the direct polycondensation reaction. The inherent viscosities of the PHAs exhibited in the range of 0.89~1.12 dL/g in DMAc or DMAc/LiCl solution. The PH-2~5 copolymers were easily soluble in strong aprotic solvents: DMAc, NMP, DMSO etc. and the PH-5 copolymer was soluble in less polar solvents such as m-creasol and pyridine with LiCl salt on heating. However, all PBOs were quite insoluble in other solvents, but only partially soluble in sulfuric acid. All copolymers (PH-2~5) could afford the flexible and tough films by solution casting. We identified that the PHAs were converted to the PBOs by the thermal cyclization reaction in the range of $200{\sim}380^{\circ}C$. The 10% weight loss temperatures and char yields of the PBOs were recorded in the range of $382{\sim}647^{\circ}C$ and 38.7~73.1% values at $900^{\circ}C$. The tensile strength and initial modulus of the PH-5 in the copolmers showed the highest values of 2.46 GPa and 49.55 MPa, respectively. The LOI values of the PHAs were in the range 26.6~29.0%, and increased with increasing 1,3-phenylene imide ring unit.

• Journal of The Korean Astronomical Society
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• v.52 no.5
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• pp.159-172
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• 2019

It is known that the number of astronomers of a country registered to the International Astronomical Union (IAU) is correlated with that country's gross domestic product (GDP). However, the robustness of this relationship could be doubted, as the fraction of astronomers joining the IAU differs from country to country. Here we revisit this correlation by using more recent data, updated as of 2017. We find a similar correlation by using the total number of astronomers and astrophysicists with PhD degrees that are working in each country, instead of adopting the number of IAU members. We confirm the existence of the correlation. We also confirm the existence of two subgroups within this correlation. One group consists of advanced European countries having a long history of modern astronomy, while the other group consists of countries having experienced recent rapid economic development. In order to determine the cause for the correlation, we obtained the long-term variations of the number of astronomers, population, and the GDP for a number of countries. We find that the number of astronomers per capita for recently developing countries has increased more rapidly as GDP per capita increased, than that for fully developed countries. We collected demographic data of the Korean astronomical community and find that it has experienced recent rapid growth. From these findings we estimate the proper size of the Korean astronomical community by considering Korea economic power and population. The current number of PhD astronomers working in Korea is approximately 310, but it should be 550 in order for it to be comparable and competitive to the sizes of the Spanish, Canadian, and Japanese astronomical communities. If current trends continue, this number will be reached by 2030. In order to be comparable to the German, French, and Italian communities, there should be 800 PhD astronomers in Korea. We discuss ways to overcome the vulnerability of the Korean astronomical community, based on the statistics of national R&D expenditure structure in comparison with that of other major advanced countries.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.66-66
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• 2003

실리콘 박막 태양전지는 저가, 대면적 생산이 가능해 최근 주택용, 발전용의 차세대 태양전지로써 부각되고 있다. 그러나, 단결정, 다결정 태양전지에 비해 상대적으로 낮은 효율특성 때문에 그 특성을 향상시키고자 하는 다양한 연구가 진행되고 있다. 비정질/마이크로결정질 실리콘 박막 태양전지에서 광흡수층으로 사용되는 i층은 광흡수를 최대화하기 위해 암전류($\sigma$$_{d}$)가 낮고 광전류($\sigma$$_{ph}$ )가 높은, 즉, 광민감도($\sigma$$_{ph}$ /$\sigma$$_{d}$)가 높은 박막을 적용해야 한다. 한편, 도핑된 윈도우층의 경우에는 넓은 밴드갭을 갖도록 하여 윈도우층에서의 광흡수가 최소화되도록 박막을 형성해야 한다.

• Fibers and Polymers
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• v.1 no.2
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• pp.67-70
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• 2000

Rosin maleic anhydride adduct (RMA)-bisester was prepared by the esterification of chlorinated RMA with hydroquinone. Phenylpyridinylcyclot.isiloxane ($D_3^{Ph,Py}$) was synthesized from phenylpyridinyldichlorosilane in the presence of zinc oxide catalyst, and amino group terminated polyphenylpyridinylsiloxane prepolymer was prepared by equilibrium polymerization of $D_3^{Ph,Py}$ with 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane. Rosinimide (PSMR) was prepared from the imidization of RMA-bisester with polyphenylpyridinylsiloxane prepolymer at 12$0^{\circ}C$ for 7 h using ${\gamma}$-butyrolactone/pyridine. It showed that PSMR had better thermal stalbility than rosinimide modified with polydimethylsiloxane.

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.27-32
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• 1997

The geometries and energies of the isomers in alkyne complexes MCl(PH3)2(η2-C2H2), M=Rh and Ir, are theoretically investigated using ab initio methods at the Hartree-Fock and up to MP4 level of theory and relativistic effective core potentials for Rh and Ir metals. The optimized structures of Rh complexes, 1-3 at MP2/ECP1 level are in good agreement with the related experimental data. The binding energies of C2H2 to d8-metal fragments are computed to be ∼55 kcal/mol. The vinylidene complexes for Rh and Ir metals are calculated to be much lower in energy than the alkyne complexes. The alkyne-vinylidene rearrangement is possible to proceed exothermically through the intermediate hydrido-alkynyl complexes, 2 or 9. Detailed comparison is given about the geometries and relative energies on Rh and Ir isomers at the various level ab initio calculations with orbital analysis.

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.349-352
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• 1988

[(Benzene)Mn$(CO)_3$]$^+$ reacts with NaP(O) (OR)$_2$ (R = Me, Et, Ph) to give the phosphonate compound 1. Compound 1 reacts with R'Li (R = Me, Ph, $^nBu, ^tBu$) to yield the isomerized compound 2 and the alkylated compound 3. [(Toluene)Mn$(CO)_3$]$^+$ reacts with NaP(O)$(OMe)_2$ to give the phosphonate complexes 1-A and 1-B. Treatment of 1-A with $^tBuLi$ in THF affords complexes 3-A and 3-B with the later major. With 1-B only the complex 3-C is formed. [(Anisole)Mn$(CO)_3$]$^+$ reacts with NaP(O)$(OMe)_2$ to give the phosphate complex 1-C, which on treatment with $^tBuLi$ and then $H_2O$ yields compound 3-D. After demetallation of compound 3-D, meta-tertbutyl-anisole is obtained in a reasonable yield.

• Nuclear Engineering and Technology
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• v.38 no.2
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• pp.163-174
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• 2006

The $Ph{\acute{e}}bus$ FP project is an international reactor safety project. Its main objective is to study the release, transport and retention of fission products in a severe accident of a light water reactor (LWR). The FPT4 test was performed with a fuel debris bed geometry, to look at late phase core degradation and the releases of low volatile fission products and actinides. Post Test Analyses results indicate that releases of noble gases (Xe, Kr) and high-volatile fission products (Cs, I) were nearly complete and comparable to those obtained during $Ph{\acute{e}}bus$ tests performed with a fuel bundle geometry (FPT1, FPT2). Volatile fission products such as Mo, Te, Rb, Sb were released significantly as in previous tests. Ba integral release was greater than that observed during FPT1. Release of Ru was comparable to that observed during FPT1 and FPT2. As in other $Ph{\acute{e}}bus$ tests, the Ru distribution suggests Ru volatilization followed by fast redeposition in the fuelled section. The similar release fraction for all lanthanides and fuel elements suggests the released fuel particles deposited onto the plenum surfaces. A blockage by molten material induced a steam by-pass which may explain some of the low releases. The revaporisation testing under different atmospheres (pure steam, $H_2/N_2$ and steam /$H_2$) and up to $1000^{\circ}C$ was performed on samples from the first upper plenum. These showed high releases of Cs for all the atmospheres tested. However, different kinetics of revaporisation were observed depending on the gas composition and temperature. Besides Cs, significant revaporisations of other elements were observed: e.g. Ag under reducing conditions, Cd and Sn in steam-containing atmospheres. Revaporisation of small amounts of fuel was also observed in pure steam atmosphere.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.900-901
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1224-1225
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• 2005

• Proceedings of the Korea Society of Design Studies Conference
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• 2001.10a
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• pp.1.1-1
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• 2001