Correlation between Branching Index and Boiling Points of Saturated Hydrocarbons

백우현,서만철,정달영 慶尙大學校 1984 論文集 Vol.23 No.2

그라프이론을 이용하여 포화탄화수소의 끊는점과 구조사이의 정량적인 관계를 유도하였다. 각 Index들을 이용하여 얻어진 상관 계수들을 끊는 점과 비교하였다. 포화탄화수소의 끊는점을 결정하는데 그라프이론에 의해 얻어진 topological parameter들이 중요한 역할을 하고 있다는 결론을 얻었다. Quantitative relationships between the structure and boilling points saturated hydrocarbons have been derived using the graph theoretical approach. The correlation coefficients of equations obtained using indices were compared favorably with boiling point. Results indicate an important role of the topological parameters in determining the boiling point of saturated hydrocarbons.

원적외선 방사체의 분광학적 특성에 관한 연구

白禹鉉 慶尙大學校 기초과학연구소 1990 基礎科學硏究所報 Vol.6 No.-

Hign efficiency far-infrared radiants similar to far-infrared radiation of black body were developed by ceramics made from mixtrue of several kinds of materials fired at 1150℃. Good results as high efficiency far-infrared radiants were obtained using natural stone as main materials and addition of transitional element oxide and clay ingredients as adjunct materials. Optical character of the ceramics powder was emissivity(ε) above 0.904 and emission wavelength about 10㎛.

고분자의 내부압에 관한 연구

성용길,백우현 동국대학교 자연과학연구소 1988 자연과학연구 논문집 Vol.8 No.-

유리전이온도 위와 아래에서 고분자의 내부압에 대한 식을 고분자의 상태 방정식에 기초하여 유도하였다. 폴리스타이렌과 폴리옥시메틸스타이렌 등과 같은 고분자의 내부압을 계산하고 실험치와 비교하였다. 그 계산된 결과는 실험 데이터와 잘 일치하였다. An equation for internal pressure (Pi) of polymers above and below glass transition temperature has been derived on the basis of the equation of state for polymers. The internal pressures for polymers such as polystyrene and polyoxymethylstyrene are calculated and compared with the experimental values of the polymers. The calculated results are found to be in good agreement with the experimental data.

비이온 계면활성제에서 친수성기와 소수성기의 화학 특성에 관한 연구

손만식,하윤식,백우현 慶尙大學校 기초과학연구소 1992 基礎科學硏究所報 Vol.8 No.-

On the basis of the principle of Bratch's electronegativity equalization, we calculated group electronegativity and group partial charge with Pauling's electronegativity parameters by the PCHARGE program. From calculated output, we investigate sturctural stability of micelle, chemical characterization of hydrophilic and hydrophobic groups, and relation between CMC and group partial charge of hydrophilic and hydrophobic groups. We know that the CMC by micelle formation depends upon group partial charge and group electronegativity. Also, the structural stability of micelle in solution is related to the electric double layer by the hydrophilic group of nonionic surfactants with H atoms in water. Therefore, it may be increased that the CMC is decreased by the increments of the higher repeating unit of the experimental hydrophilic group in comparision to the hydrophobic control group, and from the longer alkyl chain of the hydrophobic group in comparision to the hydrophilic control group.

전이 금속 산화물에 대한 원적외선 방사체의 방사 특성

손만식,이용주,백우현 慶尙大學校 기초과학연구소 1991 基礎科學硏究所報 Vol.7 No.-

In order to calculate the radiation characterization of Cr_2O_3, MnO_2, Fe_2O_3, C_0O, NiO and CuO transition metal oxides, we calculated spectral emissive power(SEP), integral emissive power(IEP), percentage of integral emissive power, regional emissivity, and total emissivity in the Far Infrared radiator at 523K. As a result, the IEP increased Fe_2O_3[MnO_2[C_0O[Cr_2O_3[NiO[CuO, the regional emissivity increased MnO_2< C_0O<Fe_2O_3<MnO_2<NiO Cr_2O_3<CuO, the total emissivity increased Cr_2O_3 Fe_2O_3<MnO_2<C_0O<NiO<CuO, and the percentage of integral emissive power increased C_0O<CuO<NiO<Fe_2O_3<MnO_2<Cr_2O_3 in the Far Infrared radiator at 523K.

유기산 추출에 의한 철 폐광산 오염토양의 복원

정의덕,강신원,백우현 한국환경과학회 2000 한국환경과학회지 Vol.9 No.1

A study on the remediation of heavily Fe ion contaminated soils from abandoned iron mine was carried out, using ex-situ extraction process. Also, oxalic acid as a complex agent was evaluated as a function of concentration, reaction time and mixing ratio of washing agent in order to evaluate Fe removability of the soil contaminated from the abandoned iron mine. Oxalic acid showed a better extraction performance than 0.1N-HCI, i.e., the concentrations of Fe ion extracted from the abandoned mine for the former at uncontrolled pH and the latter were 1,750 ppm and 1,079 ppm, respectively. The optimum washing condition of oxalic acid was in the ratio of 1:5 and 1:10 between soil and acid solution during 1 hr reaction. The total concentrations of Fe ion by oxalic acid and EDTA at three repeated extraction, were 4,554 ppm and 864 ppm, respectively. The recovery of Fe ions from washing solution was achieved, forming hydroxide precipitation and metal sulfide under excess of calcium hydroxide and sodium sulfide. In addition, the amounted of sodium sulfide and calcium hydroxide for the optimal recovery of Fe were 15g/ℓ and 5g/ℓ from the oxalic acid complexes, respectively.

물속에서 비전해질의 용해도에 관한 분자결합성 연구

成墉吉,白禹鉉 동국대학교 자연과학연구소 1984 자연과학연구 논문집 Vol.4 No.-

액체 또는 결정성 유기 비전해질의 물에 대한 용해도와 그 분자구조 사이의 정량적 관계식을 분자 결합성 연구법을 사용하여 유도하였다. 그 관계식은 녹은점 이외에 분자결합성의 항 χ에 의해서 얻어진 결과와 좋은 일치를 보였다. 또한 그 식은 물속에서 aromatic hydrocarbons, halobenzenes및 alkyl p-substituted benzoates등과 같은 비전해질에 �엿�용해도를 예측할 수 있었다. Quantitative relationships between the structure and the aqueous solubility of either liquid or crystalline organic nonelectrolytes have been derived by using the molecular connectivity approach. A good correlation wquation was obtained by the molecular connectivity term χin addition to the melting point. The equation is capable of predicting solubility for nonelectrolytes such as polycyclic aromatic hydrocarbons, halobenzenes and alkyl p-substituted benzoates in water.

유기산을 이용한 납 요염토양의 복원에 관한 연구

정의덕,강신원,박덕수,신학기,백우현 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5

A study on the removal of Pb ion from Pb-contaminated soil was carried out, using ex-situ extraction process. Tartaric acid (TA) and iminodiacetic acid sodium salt (IDA) as a washing agent were evaluated as a function of concentration, reaction time, mixing ratio of washing agent and recycling of washing agent. TA showed a better extraction performance than IDA. The optimum washing condition of TA and IDA were in the ratio of 1 : 15 and 1 : 20 between soil and acid solution during 1 hr reaction. The total concentrations of Pb ion by TA and IDA at three repeated extraction, were 368.8 ppm and 267.5 ppm, respectively. The recovery of Pb ion from washing solution was achieved by adding calcium hydroxide and sodium sulfide, form the precipitation of lead hydroxide and lead sulfide, and optimum amounts of sodium sulfide and calcium hydroxide were 7 g/ℓ for the TA washing solution and 4 g/ℓ , 5 g/ℓ for the IDA washing solution, respectively. The efficiency of recycle for TA and IDA washing solution were 78.8%, 95.1% and 89.2%, 96.6%, at third extractions under Na_2S and Ca(OH)_2, respectively.

저분자 유기산에 의한 중금속 오염토양의 복원

정의덕,원미숙,윤장희,이병호,백우현,Gardella, Joseph A. 한국환경과학회 2001 한국환경과학회지 Vol.10 No.4

For the remediation of the contaminated soil with heavy metals, Cd, Cr, Cu, and Pb, the reaction parameters were optimized. Tartaric acid (TA) and oxalic acid(OA) as a washing agent were evaluated as a function of concentration, reaction time, mixing ratio of washing agent and recovery of metals. The optimum washing conditions of TA and OA were in the ratio of 1 : 20 between soil and acid solution during 2 hr reaction under unbuffered pH solutions. At the optimized reaction conditions, the removal efficiencies were compared with that of 0.1 M HC1 and ethylenediamine tetraacetic acid(EDTA). TA showed higher efficiency on the removal of Pb than that of EDTA, which established for the remediation of contaminated soil with Pb and Cd metals. The recovery of metal ions from washing solution was achieved by adding calcium hydroxide and sodium sulfide by forming the precipitation of metal hydroxide and metal sulfide. Optimum amounts of sodium sulfide and calcium hydroxide were Cd = 25g/ℓ, Cu = 5∼10g/ℓ and Pb = 5∼10g/ℓ for the washing solution of OA and 2∼5g/ℓ for the washing solution of TA, respectively. The amounts of Na_2S and Ca(OH)_2 for the tartaric acid was less than that of oxalic acid.

Electronic Structures and Properties of the Charged Model Clusters Relating to High-$T_c$ Superconductor $Y{Ba_2}{Cu_3}{O_{7-x}}$

Paek, U-Hyon,Lee, Kee-Hag,Sung, Yong-Kiel,Lee, Wang-Ro Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.6

We have carried out an extended Huckel calculation to rationalize the role of $CuO_3$ chains and the size effect of the charged model clusters for the following charged model culsters : ${{Cu_6}{O_{21}}^{28-},\;{{Cu_6}{O_{22}}^{30-}\;,{{Cu_9}{O_{30}}^{39-}\;,{{Cu_9}{O_{32}}^{43-}\;,{{Cu_{12}{O_{38}}^{48-}\;,{{Cu_{15}{O_{50}}^{65-}\;,{{Cu_{18}{O_{54}}^{66-}\;,{{Cu_{18}{O_{55}}^{68-}\;,{{Cu_{24}{O_{70}}^{84-}\;and\;{{Cu_{27}{O_{78}}^{93-}$ for high-$T_c$ superconductor $YBa_2Cu_3O_7$: ${{Cu_6}{O_{18}}^{22-}\;,{{Cu_9}{O_{26}}^{31-}}\;,{{Cu_{12}{O_{32}}^{36-}\;,{{Cu_{15}{O_{42}}^{49-}\;,{{Cu_{18}{O_{46}}^{50-}\;,{{Cu_{24}{O_{60}}^{64-}\;and\;{{Cu_{27}{O_{66}}^{69-}$ for insulator $YBa_2Cu_3O_6$. The results show that the electronic structures and properties of the charged model clusters relating to high-$T_c$ superconductor are very sensitive to the size change of the clusters with various environmental effects, wherease those of the charged model clusters for insulator $YBa_2Cu_3O_6$ are monotonous to the size change. The $CuO_3$ chains along the b-direction may yield cooperative electronic coupling with the $CuO_2$ layers in determining both conducting and superconducting properties of $YBa_2Cu_3O_{7-x}$ system.