• 한국수소및신에너지학회논문집
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• 제28권5호
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• pp.459-464
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• 2017

The volume expansions of $Ti_{0.95}Zr_{0.05}V_{0.4}Mn_{1.45}Fe_{0.1}Cr_{0.05}$ alloy during hydrogenation with various conditions have been investigated. The theoretical volume expansion measured with XRD for this alloy with hydrogenation was 21%. The apparent volume expansion of this alloy ingot with hydrogenation was composed of two effects. One is a hydrogenation and the other is a pulverization. The apparent volume of free alloy powder was 1.8 times greater than that of an ingot, implying the pulverization effect on the apparent volume expansion is 80%. The apparent volume expansion of the alloy ingot with hydrogenation under a unconstrained condition was about 80 (${\pm}15$)%, much smaller than that of free alloy powder which expected as 118%. In addition, The apparent volume expansion of the alloy ingot with hydrogenation under a constrained condition(Al container) was about 50%, much smaller than that of the unconsrained. This reduced apparent volume expansion of the alloy ingot could be attributed to an arrangement of alloy powder keeping its original shape of the ingot even after hydrogenation.

• 대한기계학회논문집B
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• 제22권12호
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• pp.1669-1680
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• 1998

A method is developed to include the effect of volume expansion in the description of the flame dynamics using G-equation. Line volume-source is used to represent the effect of the exothermic process of combustion with source strength assigned by the density difference between the burned and the unburned region. The present model provides good agreement with the experimental results. Including volume expansion, the flow field is adjusted to accommodate the increased volume flow rate which crossing the flame front and the result predicts the same behavior of measured velocity field qualitatively. The effect of increasing volume expansion does not change the initial growth rate of flame area but increase the residence time. Consequently this effect increases the maximum area of flame front. The flame propagation in varying flow field due to volume expansion provides a promising way to represent the wrinkled turbulent premixed flames in a numerically efficient manner.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1998년도 제17회 KOSCI SYMPOSIUM 논문집
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• pp.139-154
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• 1998

Under certain circumstance, premixed turbulent flame can be treated as wrinkled thin laminar flame and its motion in a hydrodynamic flow field has been investigated by employing G-equation. Past studies on G-equation successfully described certain aspects of laminar flame propagation such as effects of stretch on flame speed. In those studies, flames were regarded as a passive interface that does not influence the flow field. The experimental evidences, however, indicate that flow field can be significantly modified by the propagation of flames through the volume expansion of burned gas. In the present study, a new method to be used with G -equation is described to include the effect of volume expansion in the flame dynamics. The effect of volume expansion on the flow field is approximated by Biot-Savart law. The newly developed model is validated by comparison with existing analytical solutions of G -equation to predict flames propagating in hydrodynamic flow field without volume expansion. To further investigate the influence of volume expansion, present method was applied to initially wrinkled or planar flame propagating in an imposed velocity field and the average flame speed was evaluated from the ratio of flame surface area and projected area of unburned stream channel. It was observed that the initial wrinkling of flame cannot sustain itself without velocity disturbance and wrinkled structure decays into planar flame as the flame propagates. The rate of decay of the structure increased with volume expansion. The asymptotic change in the average burning speed occurs only with disturbed velocity field. Because volume expansion acts directly on the velocity field, the average burning speed is affected at all time when its effect is included. With relatively small temperature ratio of 3, the average flame speed increased 10%. The combined effect of volume expansion and flame stretch is also considered and the result implied that the effect of stretch is independent of volume release.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.47-54
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• 1999

A method is developed to include the effect of volume expansion in the description of the flame dynamics using G-equation. Line volume-source is used to represent the effect of the exothermic process of combustion with source strength assigned by the density difference between the burned and the unburned region. The present model provides good agreement with the experimental results by using realistic volume expansion ratio which was not reached in the previous researches. Including volume expansion, the flow predicts the same behavior of measured velocity field qualitatively. The flame propagation in varying flow field due to volume expansion provides a promising way to represent the wrinkled turbulent premixed flames in a numerically efficient manner.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.204-210
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• 1998

A method is developed to include the effect of volume expansion in the description of the flame dynamics using G-equation. Line volume-source is used to represent the effect of the exothermic process of combustion with source strength determined by the density difference between the burned and the unburned region. Volume expansion adjusts the flow field to accommodate the increased volume flow rate crossing the flame front. Test result predicted the measured velocity field qualitatively. The method was applied to study the interaction of vortex and premixed flame. Increased volume expansion did not change the initial growth rate of flame area. However, the residence time and flame surface area increased with higher expansion ratios.

• 국제물리치료학회지
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• 제2권2호
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• pp.301-307
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• 2011

The purpose of this study was an determine whether elastic band on treadmill training might effect the chest expansion and pulmonary function of the 20's men. 40 subjects with experimental group(male: 20) and control group(male: 20) was participated in experiment. During four weeks, each group participated thirty minutes for three times per week. Subjects were assessed using pre-value and post-value measurement chest length(chest length for resting, chest expansion) and pulmonary function(forced vital capacity, forced expiratory volume at one second, FEV1/FVC, peak expiratory flow, vital capacity, tidal volume, expiratory reserve volume, inspiratory reserve volume) by the CardioTouch 3000S(BIONET, USA). These findings suggest that experimental group can be used to improve chest expansion, pulmonary function than control group. In comparison of both groups, post-test was more improved in experimental group. In conclusion, experimental group helped improving function of pulmonary volume and respiratory muscle, and thus it indicates that the functions will be more improved through the continued respiratory exercise program.

• 열처리공학회지
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• 제16권4호
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• pp.211-215
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• 2003

In this work, a new way of measuring the volume fraction of e martensite in Fe-based alloys has been proposed. Since the specific volume of ${\varepsilon}$ martensite, depending on alloy composition, is smaller than that of austenite i.e ${\gamma}$ phase, volume expansion takes place during ${\varepsilon}{\rightarrow}{\gamma}$ reverse transformation. As the amount of the volume expansion is proportional to the product of specific volume difference times the volume fraction of ${\varepsilon}$ martensite, the volume fraction of ${\varepsilon}$ martensite can be calculated by measuring the volume expansion and the specific volume difference. Such a relationship was confirmed in Fe-21Mn and Fe-32Mn-6Si alloys which undergo ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation on cooling and by cold rolling, respectively. It was also found that the former has isotropic ${\varepsilon}$ martensite while the latter has anisotropic ${\varepsilon}$ martensite.

• 한국세라믹학회지
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• 제37권6호
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• pp.576-582
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• 2000

Two type of expanding cement generally referred to as CSA with Hauyne(3CaO 3Al2O3 CaSO4) and Quick lime(CaO). Hauyne is formed to ettringite when there are presented with CaO and CaSO4, and CaO reacts wtih water to form Ca(OH)2. REcently, the mechanism of compensation and expand mortar or concrete tend to same and it has been used improving on its shrink property. The volume of cement paste varies with its water content shrink with drying and re-wetting. Concrete and mortar works are required shrinking compensation and expansion properties to reduce of potential crack. The use of expansion cement may improve on its shrinking volume changes. CSA dosages for shrinking compensation limited by cement weight, but obtained difference expansion rate with varied W/C or inorganic admixture. This paper studies expansion rate according to expansion cement dosages, water and inorganic admixtures as Silica fume. Therefor, the expansion factor has to considered before the application.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.85-86
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• 2002

For rheology investigation of lubricating oils, first phase diagrams were made from determined free volume based on density measurements and the temperature-pressure relation was estimated using the expansion coefficient of free volume and the temperature-pressure relation of the viscoelastic transition point. Next, the authors proposed the density-pressure-temperature relation and the viscosity-pressure-temperature relation of the tested oils based on the free volume and the phase diagrams. Moreover, it was shown that the Ehrenfest equation or the gradient of the phase diagram is closely related to the expansion coefficient of free volume.

• 한국식품영양과학회지
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• 제28권2호
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• pp.429-437
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• 1999

A mathematical model was established for estimating changes in pressure and volume of permeable kimchi packages. The model comprises the CO2 gas production from kimchi and permeation of O2, CO2 and N2 through the permeable film or sheet. Using the developed model, the effects of various packaging variables on the pressure and volume changes were analyzed for rigid and flexible packag es of kimchi(3% salt content) at 15oC, and then effect of storage temperature was also looked into. In case of rigid pack of 400g, using the plastic sheet of high CO2 permeability and initial vacuumizing can help to relieve the problem of pressure build up. The lower fill weight can further reduce the pressure, but will result in higher packaging cost. For the flexible package of 3 kg, highly permeable films such as low density polyethylene(LDPE) and polypropylene can reduce the volume expansion. Higher ratio of CO2 permeability to O2 and N2 permeabilities are effective in reducing the volume expansion. Increased surface area cannot contribute to reduction of volume expansion for highly permeable flexible packages of kimchi. For the impermeable packages, pressure and volume at over ripening stage (acidity 1.0%) increase with decreased temperature, while those at optimum ripening stage(acidity 0.6%) change little with temperature. Pressure of permeable rigid LDPE package increases with tem perature at any ripening stage, and temperature affects the volume of flexible LDPE package very slightly. Experimental verification of the present results and package design with economical consid eration are needed as a next step for practical application.