• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3495-3501
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• 2014

A novel crystal, the mono-protonated metformin acetate (1), was obtained and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. It was found that one of the imino group in the metformin cation was protonated along with the proton transfer from the secondary amino group to the other imino group. Its crystal structure was then compared with the previously reported diprotonated metformin oxalate (2). The difference between them is that the mono-protonated metformin cations can be linked by hydrogen bonding to form dimers while the diprotonated metformin cations cannot. Both of them are stabilized by intermolecular hydrogen bonds to assemble a 3-D supermolecular structure. The four potential tautomer of the mono-protonated metformin cation (tautomers 1a, 1b, 1c and 1d) were optimized and their single point energies were calculated by Density Functional Theory (DFT) B3LYP method based on the Polarized Continuum Model (PCM) in water, which shows that the most likely existed tautomer in human cells is the same in the crystal structure. Based on the optimized structure, their Wiberg bond orders, Natural Population Analysis (NPA) atomic charges, molecular electrostatic potential (MEP) maps were calculated to analyze their electronic structures, which were then compared with the corresponding values of the diprotonated metformin cation (cation 2) and the neutral metformin (compound 3). Finally, the possible tautomeric mechanism of the mono-protonated metformin cation was discussed based on the observed phenomena.

• 동의생리병리학회지
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• 제24권3호
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• pp.353-360
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• 2010

Huang di's Four Classics introduces the first full-scale Yin-Yang theory. The ancient idea of Yin-Yang could be classified systematically throughout Huang di's Four Classics and make itself the cause of creation, movement, and variation. The Tao of essence and Reason-Law(理法) is a single 'One'(一) and completes the reality of Tao adopting Yin-Yang as an elementary. The elementary of Yin-Yang has rules and laws and then the Tao manifest itself through Yin-Yang. The features of Yin-Yang theory in Huang di's Four Classics are placed on the explanation of the structure of the universe embodied as class and system. The class and system are the structured worlds in the space based on the upper and lower sides Yin-Yang idea(上下陰陽觀). It means the system by Yin-Yang theory, corresponding to the flat structure of the Sky and the Earth mentioned in Gaitian theory, one of the ancient theory of the universe structure. By adopting Huang di's Four Classics' Tian-zhi Yin-Yang theory(天地陰陽論) and developing the class system in human bodies, The Hwangjenegyeng appreciates human bodies as a whole. In addition, by applying Four seasons Yin-Yang theory not only to human bodies but also to the space of Liu-he(六合) and the time of Four Seasons(四時), it developed Yin-Yang theory of Huang di's Four Classics more abundantly and embodied Yin-Yang theory in many fields including physiology, pathology, diagnostics, and prescriptions.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.621-631
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• 2018

In this paper, an exact analytical solution is developed for the analysis of the post-buckling non-linear response of simply supported deformable symmetric composite beams. For this, a new theory of higher order shear deformation is used for the analysis of composite beams in post-buckling. Unlike any other shear deformation beam theories, the number of functions unknown in the present theory is only two as the Euler-Bernoulli beam theory, while three unknowns are needed in the case of the other beam theories. The theory presents a parabolic distribution of transverse shear stresses, which satisfies the nullity conditions on both sides of the beam without a shear correction factor. The shear effect has a significant contribution to buckling and post-buckling behaviour. The results of this analysis show that classical and first-order theories underestimate the amplitude of the buckling whereas all the theories considered in this study give results very close to the static response of post-buckling. The numerical results obtained with the novel theory are not only much more accurate than those obtained using the Euler-Bernoulli theory but are almost comparable to those obtained using higher order theories, Accuracy and effectiveness of the current theory.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3279-3283
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• 2013

We present an elementary pedagogical derivation of the Brillouin-Wigner and the Rayleigh-Schr$\ddot{o}$dinger perturbation theories with Epstein-Nesbet partitioning. A variant of the Brillouin-Wigner perturbation theory is also introduced, which can be easily extended to the quasi-degenerate case. A main advantage of the new theory is that the computing time required for obtaining the successive higher-order results is minimal after the third-order calculation. We illustrate the accuracy of the new perturbation theory for some simple model systems like the perturbed harmonic oscillator and the particle in a box.

• 대한한의학원전학회지
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• 제23권2호
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• pp.141-155
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• 2010

Simpo(心包. Pericardium) was described early in "Hwangjenaegyeong(黃帝內經)". But there has been a lot of criticisms about this organ. Jinsatak(陳士鐸) is one of famous doctors in Cheong(淸) dynasty. He suggested a creative Oriental medical theory and he did a profound research on Simpo(心包). "Oegyeongmieon(外經微言)" is one of his books recording his oriental medical theory in detail so it is the good documentary record for observing his theory of the Simpo(心包). So we looked into his theory of Simpo(心包) in "Oegyeongmieon(外經微言)" and also referred to his other books. You might be able to get a viewpoint of utilizing Simpo(心包) in several ways through reading this paper.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.27-33
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• 1995

A time-dependent large deformation fracture theory is developed for application to soft biological tissues. The theory uses the quasilinear viscoelastic theory of Fung, and particularizes it to constitutive assumptions on polyvinyl-chloride (PVC) (Part I) and cartilage (Part II). This constitutive theory is used in a general viscoelastic theory by Christensen and Naghdi and an energy balance to develop an expression for the fracture toughness of the materials. Experimental methods are developed for measuring the required constitutive parameters and fracture data for the materials. Elastic stress and reduced relaxation functions were determined using tensile and shear tests at high loading rates with rise times of 25-30 msec, and test times of 150 sec. The developed method was validated, using an engineering material, PVC to separate the error in the testing method from the inherent variation of the biological tissues. It was found that the the proposed constitutive modeling can predict the nonlinear stress-strain and the time-dependent behavior of the material. As an approximation method, a pseudo-elastic theory using the J-integral concept, assuming that the material is a time-independent large deformation elastic material, was also developed and compared with the time-dependent fracture theory. For PVC. the predicted fracture toughness is $1.2{\pm}0.41$ and $1.5{\pm}0.23\;kN/m$ for the time-dependent theory and the pseudo-elastic theory, respectively. The methods should be of value in quantifying fracture properties of soft biological tissues. In Part II, an application of the developed method to a biological soft tissue was made by using bovine humeral articular cartilage.

• Computers and Concrete
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• 제25권3호
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• pp.225-244
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• 2020

The influence of boundary conditions on the bending and free vibration behavior of functionally graded sandwich plates resting on a two-parameter elastic foundation is examined using an original novel high order shear theory. The Hamilton's principle is used herein to derive the equations of motion. The number of unknowns and governing equations of the present theory is reduced, and hence makes it simple to use. This theory includes indeterminate integral variables and contains only four unknowns in which any shear correction factor not used, with even less than the conventional theory of first shear strain (FSDT). Unlike any other theory, the number of unknown functions involved in displacement field is only four, as against five, six or more in the case of other shear deformation theories. Galerkin's approach is utilized for FGM sandwich plates with six different boundary conditions. The accuracy of the proposed solution is checked by comparing it with other closed form solutions available in the literature.

• Korean Journal of Mathematics
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• 제17권3호
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• pp.331-340
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• 2009

We show the existence of nonconstant periodic solution for the nonlinear Hamiltonian systems with some nonlinearity. We approach the variational method. We use the critical point theory and the variational linking theory for strongly indefinite functional.

• 천문학논총
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• 제26권2호
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• pp.55-70
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• 2011

Cosmological linear perturbation theory has fundamental importance in securing the current cosmological paradigm by connecting theories with observations. Here we present an explanation of the method used in relativistic cosmological perturbation theory and show the derivation of basic perturbation equations.

• Journal of Acupuncture Research
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• 제27권6호
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• pp.23-30
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• 2010

Objectives : This study was undertaken in order to establish the composite principles of fomulas through the of Sa-am acupuncture therapy and the theory of sovereign, minister, assistant and courier. Methods : We analyzed the formula construction of Sa-am acupuncture therapy, and applied the theory of sovereign, minister, assistant and courier that was referred to in the preface of "Essential Rhymes on Acupuncture and Moxibustion by Master Sa-am" to the analysis of formula construction. Results & Conclusions : 1. Sa-am acupuncture therapy was acupuncture and moxibustion method that inherited and developed progress contents of Chinese traditional acupuncture and moxibustion. 2. The theory of sovereign, minister, assistant and courier was based on the idea that acupuncture and herbal medicine had the same origins. 3. Formula constructions of Sa-am acupuncture therapy were formed complicatedly, but reflected the theory of sovereign, minister, assistant and courier. 4. The supplementing acupuncture point that is Chunbu-point in other merdian became Sovereign, the draining acupuncture point that is Chunbu-point in other merdian became Minister, and the supplementing and draining acupuncture points in same merdian became Assistant and Courier that mean leading merdian points.