• Korea-Australia Rheology Journal
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• 제14권3호
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• pp.129-138
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• 2002

A cationic surfactant, cetyltrimethylammonium $\rho$-toluenesufonate (CTA$\rho$TS), forms long threadlike micelles in aqueous solution. The threadlike micelles make concentrated entanglement networks, so that the solution shows pronounced viscoelastic behavior as concentrated polymer systems do. However, a mechanism for a process responsible for the longest relaxation time of the threadlike micellar system is different from that of semi-dilute to concentrated polymer systems. The threadlike micellar system exhibits unique viscoelasticity described by a Maxwell model. The longest relaxation time of the threadlike micellar system is not a function of the concentration of CTA$\rho$TS, but changes with that of $\rho$-toluenesufonate ($\rho$$TS^{-}$) ions in the bulk aqueous phase supplied by adding sodium $\rho$-toluenesulfonate (NapTS). The rates of molecular motions in the threadlike micelles are not influenced by the concentration of $\rho$$TS^{-}$ anions, therefore, molecular motions in the threadlike micelles (micro-dynamics) are independent of the longest relaxation mechanism (macro-dynamics). A nonionic surfactant, oleyldimethylamineoxide (ODAO), forms long threadlike micelles in aqueous solution without any additives. The aqueous threadlike micellar system of ODAO also shows Maxwell type viscoelastic behavior. However, the relaxation mechanism for the longest relaxation process in the system should be different from that in the threadlike micellar systems of CTA$\rho$TS, since the system of ODAO does not contain additive anions. Because increase in the average degree of protonation of head groups of ODAO molecules in micelles due to adding hydrogen bromide causes the relaxation time remarkably longer, changes in micro-structure and micro-dynamics in the threadlike micelle are closely related to macro-dynamics in contrast with the threadlike micellar system of CTA$\rho$TS.

• Steel and Composite Structures
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• 제46권6호
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• pp.805-821
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• 2023

This study developed an evaluation system to explore the effect of the environmental temperature on the stress redistribution produced by cable stress relaxation of structural members in a steel cable-stayed bridge. The generalized Maxwell model is used to estimate stress relaxation at different temperatures. The environmental temperature is represented using the thermal coefficients and temperature loads. The fmincon optimization function is used to determine the set of stress relaxation parameters at different temperatures for all cables. The ABAQUS software is employed to investigate the stress redistribution of the steel cable-stayed bridge caused by the cable stress relaxation and the environmental temperature. All of these steps are set up as an evaluation system to save time and ensure the accuracy of the study results. The developed evaluation system is then employed to investigate the effect of environmental temperature and cable type on stress redistribution. These studies' findings show that as environmental temperatures increased up to 40 ℃, the redistribution rate increased by up to 34.9% in some girders. The results also show that the cable type with low relaxation rates should be used in high environmental temperature areas to minimize the effect of cable stress relaxation.

• Steel and Composite Structures
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• 제44권6호
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• pp.753-768
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• 2022

In this study, a graphical automatic system is developed in order to investigate the stress redistribution of structural members in a steel cable-stayed bridge. The generalized Maxwell model is selected for stress relaxation estimation, and it is carefully verified and applied to all the cable members of a steel cable-stayed bridge to investigate its stress relaxation. A set of stress relaxation parameters in all cables is determined using the fmincon optimization function. The stress redistribution of the steel cable-stayed bridge is then analyzed using ABAQUS. To shorten the investigation time, all the aforementioned phases are built up to be an automatic system. The automatic system is then employed to investigate the effect of cable cross-section areas and girder spans on stress redistribution. The findings from these studies show that the initial tension in the cables of a steel cable-stayed bridge should be kept to less than 55% of the cable's ultimate strength to reduce the effect of cable stress relaxation. The cable space in a steel cable-stayed bridge should be limited to 15,000 mm to minimize the effect of cable stress relaxation. In comparison to other structural members of a steel cable-stayed bridge, the girders experience a significant stress redistribution.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.727-735
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• 2002

Proton coupled carbon-13 relaxation experiment was performed to investigate the effect of vicinal protons on spin-lattice relaxation of methylene carbon-13 in n-undecane. A BIRD type pulse sequence was employed as a way to check the validity of describing the 13CH2 moiety as an isolated AX2 spin system. The results show that the presence of vicinal protons exerts substantial influence on the relaxation of methylene carbon-13, indicating that it is not a very good approximation to treat a methylene moiety as an isolated AX2 spin system.

• 동의신경정신과학회지
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• 제17권3호
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• pp.57-65
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• 2006

Objectives: The purpose of this research is to investigate the effects of Benson's Relaxation Technique on autonomic nervous system for normal subjects with Heart Rate Variability(HRV) and find out relationship with anti - stress effects. Methods: First, Benson's Relaxation Technique was applied on 5 normal subjects for three weeks. Then HRV was examined for 15 minutes Benson's Relaxation Technique application. Next, Benson's Relaxation Technique each 8 times was applied on 5 normal subjects for 1 weeks. Then :HRV was examined each 5 minutes before and after Benson's Relaxation Technique application. Results: 1. SDNN, SDSD increased continuously in HRV for three weeks Benson's Relaxation Technique application. 2. Mean HRV, SDNN, SDSD were significant different in HRV between before and after Benson's Relaxation Technique application at fourth week. Conclusion: The results suggest that Benson's Relaxation Technique application have shown anti-stress effects and the more Benson's Relaxation Technique is repeated, the more effective.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.21-29
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• 1993

For the study of relaxation processes in complex spin system, a general master equation, which can be used to simulate a vast range of pulse experiments, has been formulated using the Liouville representation of quantum mechanics. The state of a nonequilibrium spin system in magnetic field is described by a density vector in Liouville space and the time evolution of the system is followed by the application of a linear master operator to the density vector in this Liouville space. In this master equation the nuclear spin relaxation due to intramolecular dipolar interaction or randomly fluctuating field interaction is explicitly implemented as a relaxation supermatrix for a strong coupled two-spin (1/2) system. The whole dynamic information inherent in the spin system is thus contained in the density vector and the master operator. The radiofrequency pulses are applied in the same space by corresponding unitary rotational supertransformations of the density vector. If the resulting FID is analytically Fourier transformed, it is possible to represent the final nonstationary spectrum using a frequency dependent spectral vector and intensity determining shape vector. The overall algorithm including relaxation interactions is then translated into an ANSIFORTRAN computer program, which can simulate a variety of two dimensional spectra. Furthermore a new strategy is tested by simulation of multiple quantum signals to differentiate the two relaxation interaction types.

• 정보학연구
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• 제8권3호
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• pp.57-71
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• 2005

This thesis is to explore the relaxation of restrictions at the acquisition of own stock, and to get the results from this system many countries' legislations were alluded as model cases for Korean system. In comparing with America, Japan, Europe(EC 2nd Commercial Law), and England, the final suggestion for Korean companies law as follows: The solution of problems which is derived from the acquisition at own stock in enterprise is to make the optimum situation for the economic development and stability of stock market. So, to solve these problems needs the relaxation of restrictions for this system and by the relaxation of restrictions can get the distribution of its profit to stockholder, and the compensation for employers and employees. Furthermore, through this system the company can achieve the protection against M&A and the supply of company funds. In conclusion the relaxation of restrictions at the acquisition of own stock is acknowledged the necessity, but the problems that would be followed must be necessarily minimized, and to do so, the legal system has to be molded for this purpose and the its procedure(that is, accounting deal of own stock, the fictitious dividend, and non-appliance of tendency control) has to be prior to the legal system.

• 한국자기공명학회논문지
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• 제11권1호
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• pp.1-9
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• 2007

An unequal site exchanging system induced by restricted rotation of 9-methyl group in 1,8-dichloro-9-triptycene has been studied by spin-lattice relaxation and 2D-EXSY experiments. The exchange rate obtained from relaxation studies is very well coincident to the result of line shape analysis, and the difference of the relaxation times ($T_1$) in two different sites has an important role to analyze 2D-EXSY experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.706-711
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• 2001

This paper represents a relaxation matching algorithm based on global structure constraint satisfaction. Relaxation matching algorithm is a conventional approach to the matching problem. However, we confronted some problems such as null-matching and multi-matching problems by just using the relaxation matching technique. In order to solve the problems, in this paper, the matching problem is regarded as constraint satisfaction problem, and a relaxation matching algorithm is proposed based on global structure constraint satisfaction. The proposed algorithm is applied a landslide picture to show the effectiveness. When the algorithm is processed at landslide inspecting and monitoring system, motion parameters such as displacement area and its direction are computed. Once movement is recognized, displacements are estimated graphically with statistical amount in the image plane. Simulation has been done to prove the proposed algorithm by using time-sequence image of landslide inspection and monitoring system.

• 한국자기공명학회논문지
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• 제10권1호
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• pp.59-73
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• 2006

Spin-lattice relaxation pathway of $CH_2$ spin system by two dimensional NOESY sequence has been discussed. Two-dimensional spectra governed by dipolar relaxation mechanism were simulated in term of transfer mode, the generalization of conventionally used magnetization mode in one dimension. The transfer matrix directly related to the Redfield relaxation matrix can be constructed by the multiplet of transfer mode. The observable relaxation transfer modes causes to variation of the off-diagonal signal intensity of phase sensitive NOESY spectra from which variable spectral density can be extracted with simple group theoretical calculation. The variation of the J-coupling peak intensity as a function of the mixing time in 2-D spectra for $n-Undecane-5-^{13}C$ and Bromoacetic $2-^{13}C$ acid has been theoretically traced.