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Stability of the Pentagon Structure of Water Cluster
Yoon, Byoung-Jip,Jhon, Mu-Shik Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.1
A hexagonal hexamer of water cluster is optimized by ab initio method using the 4-31G basis set. At this geometry the nonadditive many-body interactions are calculated. The ab initio calculation with large basis set [T. H. Dunning, J. Chem. Phys., 53, 2823 (1970); 54, 3958 (1971)] shows that a pentagonal unit is rather stable among several kinds of clustering units of water molecules.
Yoon, Byoung-Jip Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.8
The anomalies that appear at every multiple of 15 ℃ in the viscosity of a thin liquid film of water and of water near solid interfaces are explained in this paper by comparing the thermal wavelength and molecular free volume of water, and quantum numbers are found. The possibility that these anomalies are related to the preferred and/or lethal temperatures of organisms is considered. The toxicity of heavy water (D₂O) can also be explained with this approach.
Phase Transition and Approximated Integral Equation for Radial Distribution Function
Yoon, Byoung-Jip,Jhon, Mu-Shik Korean Chemical Society 1986 Bulletin of the Korean Chemical Society Vol.7 No.1
A reduced condition for liquid-gas phase transition from the singularity of compressibility is derived using diagrammatic approach and is examined in the hard sphere system. The condition turns out that the Percus-Yevick and the Hyper-Netted-Chain approximation never conceive the idea of phase transition, and explains that the liquid-gas transition does not exist in hard sphere system. The solid-fluid transition is considered on the viewpoint of correlation function and diagrammatic analysis.
The Anomalies of Supercooled Water
Yoon, Byoung-Jip,Jhon, Mu-Shik Korean Chemical Society 1984 Bulletin of the Korean Chemical Society Vol.5 No.2
The anomalous behaviors of supercooled water are explained by using a two-solid-like structure model in which an equilibrium is assumed between open structures and closed structures. Besides these structures, small fraction of monomer exists in liquid water. The anomalies of liquid water are classified into two groups: structural and energetic. The structural anomalies appear in enlarged fashions in a supercooled state where the free volume is small.
The Calculation of Hugoniot Adiabatics and Viscosity of Shock Compressed Water
Baik, Dae-Hyun,Jhon, Mu-Shik,Yoon, Byoung-Jip Korean Chemical Society 1986 Bulletin of the Korean Chemical Society Vol.7 No.4
The Hugoniot adiabatics and viscosity of shock compressed water have been calculated by applying the significant structure theory of water. To consider the effects of pressure and temperature, the sublimation energy has been expressed by the spherically averaged Stillinger-Rahman ST2 potential. Good agreements between theory and experiment are obtained in the whole extreme ranges of shock wave condition up to 100 GPa (lMbar).
Theoretical Study on Structures and Energetics of Small Water Clusters
Park Yeong Jae,Kang Young Kee,Yoon Byoung Jip,Jhon Mu Shik Korean Chemical Society 1982 Bulletin of the Korean Chemical Society Vol.3 No.2
A study of small water clusters composed of two to seven molecules has been performed by using the revised empirical potential function for conformational analysis (REPFCA). Various structures of clusters have been investigated and the relative probability of cluster per molecule is discussed. In general, cyclic structures of water clusters are more favorable than open structures. It is found that cyclic pentamer is the most favorable unit structure in the water cluster.
나승창,윤병집,전상일,Ra, Seung Chang,Yoon, Byoung Jip,Jeon, Sang Il Korean Chemical Society 1995 대한화학회지 Vol.39 No.8
수용액에서 폴리에틸렌 옥사이드(PEO)의 구조성질이 일련의 요소용질들의 물 구조 간섭 정도관점에서, 16$^{\circ}C$에서 점도계법으로 연구되어졌으며, 또한 16$^{\circ}C$와 25$^{\circ}C$의 두 온도에서 PEO에 대한 요소와 메틸요소의 양변화가 마찬가지로 행해졌다. 결과는 16$^{\circ}C$에서 분자량이 $1.0{\times}10^5$인 PEO의 요소들에 의한 사슬 펴짐은 25$^{\circ}C$에서 분자량이 $8.0{\times}10^3$인 PEO의 경우와 비슷한데, 이것을 요소들의 물 구조 간섭 정도가 두 경우에 비슷하기 때문이라 설명했다. 요소는 PEO사슬을 펴지게 한다. 분자량이 $1.0{\times}10^5$인 PEO는 그 자체내에 소수성 부분을 가지는데, 이것은 다음과 같이 대략 두 부분으로 분류할 수 있다. 하나는 16$^{\circ}C$에서 많이 나타나며, 분자내 소수성 상호인력을 할 수 있는 내부 소수성기와, 다른 하나는 25$^{\circ}C$에서 많이 나타나며, 외부에서 가해진 소수성 용질들과 분자간 소수성 상호인력을 할 수 있는 바깥쪽으로 노출된 소수성기이다. The conformational properties of poly(ethylene oxide) (PEO) in aqueous solutions are studied by viscometry with respect to the water structure perturbing capabilities of a series of urea solutes at $16^{\circ}C$, and experiments for the effect of amounts of urea and methylurea on PEO at 16 and $25^{\circ}C$ are also performed. The results show that the chain expansion, by ureas, of PEO of $1.0{\times}10^5$ molecular weight at $16^{\circ}C$ is similar to that of PEO of $8.0{\times}10^3$ molecular weight at $25^{\circ}C$ with respect to the water structure perturbation. Urea and methylurea make the PEO chain expand by the perturbation of water structure around PEO and by the hydrophobic interaction between methylurea and PEO, respectively. PEO of $1.0{\times}10^5$ molecular weight has hydrophobic sites on it, which are roughly classified into two parts; one is the inner hydrophobic groups which can interact between themselves (intramolecular hydrophobic interaction) and prevails at $16^{\circ}C$, and the other is the outer, exposed hydrophobic groups which can interact with the added hydrophobic solute (intermolecular hydrophobic interaction) and prevails at $25^{\circ}C.$
Sang Il Jeon,Hak-Kyu ChoI,Seung Chang Ra,Byoung Jip Yoon Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.9
Poly(ethylene oxide) (PEO) in aqueous solutions has a hydrophobic character which can induce the hydrophobic interaction between its nonpolar parts. The hydrophobic properties of aqueous PEO solutions are studied by the viscometry in terms of the water structure-making and -breaking capabilities of added solutes of ureas. The results show that the contracted conformation of PEO of low molecular weight, namely poly(ethylene glycol) (PEG), does not result from the hydrophobic interaction between the nonpolar parts of PEO but it can participate in a hydrophobic interaction between the nonpolar parts of PEO and added ureas solutes with nonpolar groups, which can induce a large hydrodynamic volume and increase the viscosity. On the other hand, the PEO of large molecular weight seems to behave like any other water soluble polymers with nonpolar parts and its conformation in aqueous solutions is well explained in terms of water structure perturbing capabilities of added ureas.