• 대한화학회지
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• 제14권1호
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• pp.51-59
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• 1970

Methyl에서 n-butyl까지의 n-alkylamine 염산염동족체($RNH_3Cl$)의 "겉보기몰랄부피"(apparent molal volume)${\phi}_v$를 30$^{\circ}C$에서 여러가지 조성의 methanol-물 혼합액을 써서 측정하였다. 아민염의 농도는 0.01M까지, 밀도는 부력법을 적용하여 소수점이하 5위까지 택하였다. 관측된 ${\phi}_v$값을 무한대의 농도 쪽으로 extapolation하여 "분몰랄부피"(partial molal volume)$\bar{V}^{\circ}$V를 구하였다. 실험결과는 용질입자의 크기, charge 및 hydrophobic effect등에 관하여 논의되었고 또한 동족체간에일정한 몰랄부피차(${\Delta}\bar{V}^{\circ}$)를 갖는다는 사실과 아울러 혼합용매의 구조에 대하여도 검토하였다. 메탄올-물 0.1몰분율(m.f.)에서는 물의 구조증대로 cation의 "분몰랄부피($\bar{V}^{\circ}_+$)가 최소이고, 한편 0.4m.f. 에서는 charge 효과에 의한 electrostriction effect의 최대화 free volume이 최소라는 사실들이 관찰되었다.

• Macromolecular Research
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• 제12권6호
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• pp.564-572
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• 2004

Modem applications could benefit from multifunctional materials having anisotropic optical, electrical, thermal, or mechanical properties, especially when coupled with locally controlled distribution of the directional response. Such materials are difficult to engineer by conventional methods, but the electric field-aided technology presented herein is able to locally tailor electroactive composites. Applying an electric field to a polymer in its liquid state allows the orientation of chain- or fiber-like inclusions or phases from what was originally an isotropic material. Such composites can be formed from liquid solutions, melts, or mixtures of pre-polymers and cross-linking agents. Upon curing, a 'created composite' results; it consists of these 'pseudofibers' embedded in a matrix. One can also create oriented composites from embedded spheres, flakes, or fiber-like shapes in a liquid plastic. Orientation of the externally applied electric field defines the orientation of the field-aided self-assembled composites. The strength and duration of exposure of the electric field control the degree of anisotropy created. Results of electromechanical testing of these modified materials, which are relevant to sensing and actuation applications, are presented. The materials' micro/nanostructures were analyzed using microscopy and X-ray diffraction techniques.

• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.76-80
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• 2011

This paper proposes a method to calculate magnetostrictive forces, displacement, and vibration modes of a large-scale Brushless DC(BLDC) motor by using a magneto-mechanically strong coupling formulation. The force is calculated using the energy method with magnetostrictive stress tensor. The mechanical vibration modes are also analyzed by using the principle of Hamilton and the calculated magneto-elastic forces acting on the surfaces of the stator. To verify the algorithm, 3 MW BLDC motor is simulated, and the forces, displacements, and vibration modes are calculated. The result shows that the mechanically stressed core has more deformation or displacements than those of the normal condition.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1254-1258
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• 2007

Electro-active polymer (EAP), one of the smart materials, is a new alternative offering ultra-precise movements and bio-compatibility. We present the results of the design, fabrication, and performance evaluation of a fabricated diaphragm-type polymer actuator using segmented polyurethane(SPU). This paper illustrates the relationship between the elastic modulus and maximum deflection as a key property of the Maxwell stress effect and also presents the relationship between the dielectric constant and maximum deflection as a key property of the electrostriction effect, especially in polymer actuators using SPU. A diaphragm-type actuator was used to induce an equation of the vertically distributed load by using a fully clamped circular plate as the boundary condition. To verify the equation, the results were compared to the data measured from load cell. In the near future, a low-cost check valves and bio-robot can be applied by its actuators.

• 대한화학회지
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• 제13권3호
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• pp.195-198
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• 1969

Determination of partial molal volumes of anilinium chloride isopropanol-water mixtures at 30.00$^{\circ}$showed a distinct minimum at 0.20 mole fraction isopropanol. This was interpreted as maximum in electrostriction effect and minimum in water structure. The depth in $\bar{V}^{\circ}$for alcohol-water mixtures was in the order MeOH > i-PrOH > EtOH, which indicated the importance of microscopic structure around ions.

• 정보저장시스템학회논문집
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• 제10권2호
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• pp.61-64
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• 2014

Vibration and acoustic noise arise from the Multilayer Ceramic Capacitor (MLCC) because of the piezoelectric effect of dielectric substance which consists of $BaTiO_3$. However, the phenomenon is not analyzed clearly because the MLCC shows different behavior compare with ordinary piezoelectric substance like PZT. Thus, MLCC was tested under the several DC bias conditions and heat treatment effect was also tested and analyzed in this paper. From the test, MLCC shows not only piezoelectric effect but also another physical phenomenon like electrostriction. Also, it was verified that DC bias affect to the piezoelectric constant of MLCC.

• Bulletin of the Korean Chemical Society
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• 제5권3호
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• pp.112-117
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• 1984

The association constants (K) of 3,5,N-trimethyl pyridinium iodide in 95 volume percent ethanol-water mixed solvent were determined by a modified UV and conductance method at $25^{\circ},\;30{\circ},\;40{\circ}\;and\;50{\circ}C$ over the pressure range 1 to 2000 bars. The association process is enhanced with increasing pressure and decreasing temperature. From K values, we obtained the total partial molar volume change (${\Delta}V$) and some thermodynamic parameters. The electrostriction volume (${\Delta}V_{el}$) and intrinsic volume (${\Delta}V_{in}$) were also evaluated. The values of ${\Delta}V,\;{\Delta}V_{el},\;{\Delta}V_{in}$ are negative, negative and positive, respectively, and the absolute values of all these three decrease with increasing pressure and temperature. The ion-pair size (a) were varied 3 to 6 ${\AA}$, with pressure and temperature. The solvation number (n) decreased from 2 to 0.5 with increasing temperature.

• Bulletin of the Korean Chemical Society
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• 제6권5호
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• pp.259-263
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• 1985

Rate Constants for the solvolysis of p-methylbenzyl chloride in various ethanol-water mixtures were studied at 30 and $40^{\circ}C$ under various pressures up to 1600 bar. The rates of reaction were increased with increasing temperature and pressure, and decreased with increasing solvent composition of ethanol mole fraction. From the rate constants, the values of the activation parameters (${\Delta}V^{\neq},{\Delta}{\beta}^{\neq},{\Delta}H^{\neq}\;and\;{\Delta}S^{\neq}$) were evaluated. The values of ${\Delta}V^{\neq}\;and\;{\Delta}{\beta}^{\neq}$ exhibit the extremum behavior at about 0.30 mole fraction of ethanol. This behavior is discussed in terms of solvent structure variation (electrostriction). From the relation between the reaction rate and the dielectric constant of solvent or the number of water molecule participated in the transition state, it could be postulated that the reaction proceeds through $S_N1$ mechanism.

• Bulletin of the Korean Chemical Society
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• 제7권3호
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• pp.163-166
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• 1986

A new paraffin salt bridge was developed for the concentration cell in high pressure system. The emf values of the concentration cells were measured to calculate the activity coefficients of the electrolytic ions depending upon the pressure of the system. The activity coefficients of sodium, chloride and bromide ions increase with the temperature of the cell and decreased, nearly half at 2500 bars, $20^{\circ}C$, with the pressure. These results can be explained to be attributed to the volume change of the hydrated ion due to the electrostriction. The volume change decreased with pressure due to an increase in the degree of the hydration.

• 대한화학회지
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• 제15권3호
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• pp.159-163
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• 1971

The relative viscosities ${\eta}_r$ of a series of homologous tetraalkylammonium chlorides $Me_4NCl,\;Et_4NCl,\;Pr_4NCl\;and\;Bu_4NCl$ in a series of isopropanol-water mixtures have been determined at $30^{\circ}C$ using Ubbelohde-type viscometers. The viscosity data have been interpreted in terms of viscosity A-and B-coefficients calculated from the Jones-Dole equation, ${\eta}_r=1+AC^{1/2}+BC$. The results indicate that the structure-breaking effect of chloride ion is maximum at 0.l~0.15 mole fraction isopropanol, while the size effect(Einstein effect) of the larger $R_4N^+$ ions is maximum at 0.2~0.25 mole fraction. The results also indicate that in aqueous and water-rich solutions the larger $R_4N^+$ ions (e.g. $Pr_4N+, Bu_4N^+$) appear to be excellent structure-formers and that the viscosities of solutions is not strongly affected by the electrostriction effect of chloride ion.