• International Journal of Fluid Machinery and Systems
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• 제2권2호
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• pp.127-135
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• 2009

A conventional centrifugal pump causes a drastic deterioration of air-water two-phase flow performances even at an air-water two-phase flow condition of inlet void fraction less than 10% in the range of relatively low water flow rate. Then we have developed a two-phase flow centrifugal pump which consists of a tandem arrangement of double rotating cascades and blades of outer cascade have higher outlet angle more than $90^{\circ}$. In design of the two-phase flow pump for various sized and operating conditions, similarity relations of geometric dimensions to hydraulic performances is very useful. The similarity relations of rotational speed, impeller diameter and blade height are investigated for the developed impeller in the present paper. As the results, the similarity law of rotational speed and impeller diameter is clarified experimentally even in two-phase flow condition. In addition, influences of blade height on air-water two-phase flow performances indicate a little difference from the similarity relations.

• 한국세라믹학회지
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• 제16권4호
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• pp.206-212
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• 1979

The phase relations and microstructure appeared at 1700℃ in a system of Si3N4-Al2O3-SiO2 were studied. The samples were pressurelessly sintered at 1700℃ for 1hr and reheated at 1600℃ for 1hr under nitrogen atmosphere. The compounds formed were identified by X-ray diffraction method and the microstrues were observed by SEM. The stable phases appeared in this system were X-phase, Si2ON2, β'-Si3N4 and Mullite. From the results of those experiments, it was concluded that the X-phase has very close composition to that proposed by G, K. Layden, Si3Al6O12N2. SEM photographs showed that Si2ON2 was a plate phase and X-phase was a rectagular plate phase.

• 한국광물학회지
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• 제8권1호
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• pp.13-22
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• 1995

Phase relations of the Pd-Sb system were investigated using the sealed-capsule technique; the quenched run products were studied by reflected light microscopy, X-ray diffraction, and electron microprobe analysis. Eight binary phases were confirmed to exist in the system: Pd20Sb7, Pd31Sb12, Pd8Sb3 (mertieite II), Pd5Sb2, Pd2Sb, Pd5Sb3, PdSb (sudburyite), and PdSb2, (unnamed PdSb2), The X-ray powder diffraction data of all the phases, except for Pd5Sb3, however, may be indexable on an orthorhombic cell, space group Cmc2, with a=3.362(1), b=17.484(7), c=6.934(2)$\AA$. Some physical properties as well as re-determined cell parameters are newly established. A revised phase relations of the Pd-Sb system are presented.

• 천문학회지
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• 제54권4호
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• pp.121-128
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• 2021

It has been known that the global asteroseismic parameters as well as the stellar acoustic mode parameters vary with stellar magnetic activity. Some solar-like stars whose variations are thought to be induced by magnetic activity, however, show mode frequencies changing with different magnitude and phase unlike what is expected for the Sun. Therefore, it is of great importance to find out whether expected relations are consistently manifested regardless of the phase of the stellar magnetic cycle, in the sense that observations are apt to cover a part of a complete cycle of stellar magnetic activity unless observations span several decades. Here, we explore whether the observed relations of the global seismic parameters hold good regardless of the phase of the stellar magnetic cycle, even if observations only cover a part of the stellar magnetic cycle. For this purpose, by analyzing photometric Sun-as-a-star data from 1996 to 2019 covering solar cycles 23 and 24, we compare correlations of the global asteroseismic parameters and magnetic proxies for four separate intervals of the solar cycle: solar minima ±2 years, solar minima +4 years, solar maxima ±2 years, and solar maxima +4 years. We have found that the photometric magnetic activity proxy, S_ph, is an effective proxy for the solar magnetic activity regardless of the phase of the solar cycle. The amplitude of the mode envelope correlates negatively with the solar magnetic activity regardless of the phase of the solar cycle. However, relations between the central frequency of the envelope and the envelope width are vulnerable to the phase of the stellar magnetic cycle.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2168-2176
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• 2012

Relations between fitted parameters for photoionization spectra both below and above the thresholds in the systems involving 3 channels are obtained using phase-shifted version of the multichannel quantum-defect theory. Analytical continuation of the photoionization cross sections in the form of ${\langle}{\sigma}_{below}{\rangle}_{v_{below}}={\sigma}_{above}$ examined using several representations.

• 정보관리학회지
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• 제4권2호
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• pp.47-61
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• 1987

하나의 주제가 분류표 상에서 둘 이상의 기본주제로 구성된 경우를 콜론분류법에서는 복합주제라고 하고, 이 복합주제를 구성하고 있는 각 주제 간의 관계를 불완전한 결합이라고 한다. 상이한 두 주제가 이와 같은 결합을 구성할 때 개개의 구성요소를 상이라고 하고 주제의 패싯 관계와 구분하고 있으며 3가지 수준에서 각각 6가지 종류로 규정하고 있다. DDC 나 UDC 등에서도 부분적으로는 이러한 상 관계가 도입되고 있으나, 그 관계나 수준에 대한 규정이 마련되어 있지 않으며 더우기 이들 관계의 표현방법이 제시되어 있지 않고 있다. 전통적인 체계분류법에서도 복합주제의 처리에 있어, 상 관계의 설정 및 주제구성을 위한 구체적인 방법이 더욱 확대, 도입되어야 할 것이다.

• 산업기술연구
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• 제18권
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• pp.277-287
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• 1998

In this work continuous thermodynamics was adopted for describing the influence of copolymer polydispersity on phase separations in random copolymer solutions. Continuous themodynamic frameworks were formulated using the Flory-Huggin's excess Gibbs free energy model in which the concentration- and temperature-depentent terms of interaction parameter x were modified. Cloud-point curves and coexistence curves of poly(ethylene-vinylactate)/methylacetate solutions and poly(ehtylene-vinylacetate)/ethylacetate solutions were measured, and experimental data were fitted with theoretical relations formulated in this work. Calculated could-point curves were more good ageeable with experimental data than the modified Flory-Huggins's relations. Coexistence curves which were evaluated by using parameters of x estimated from experimental cloud-point curves, were found to coincide with experimental data.

• Nuclear Engineering and Technology
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• 제28권2호
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• pp.103-117
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• 1996

본 논문에서는 증기폭발의 전파과정을 해석하기 위한 수학적 모델을 제시하였다. 이 모델은 용융물, 용융파편, 그리고 냉각재 기상과 액상 등 4상 유체의 2차원적인 천이거동을 지배방정식 및 관련상관식의 수치적 해를 구함으로서 예측할 수 있다. 모델에 사용된 주요 상관식은 용융물 분쇄, 냉각재 상변화, 에너지 교환, 그리고 운동량 교환항으로 구성되어 있다. 그리고, 냉각재(물)의 상태방정식은 냉각재의 기상과 액상 사이의 열역학적 인 비평형을 허용할 수 있는 독특한 형태로 구성되었다. 주석 /물의 중기폭발에 대한 예제계산을 수행한 결과 본 모델이 폭발의 전파속도 및 압력 -비록 그 정량적인 값은 관련상관식의 인자들에 좌우되지마는- 등의 증기폭발 전파과정의 주요현상을 적절히 모사할 수 있음을 알 수 있었다. 또한 중요한 초기변수(중기 분율, 용융물 분율) 및 관련상관식에 대한 민감도 분석도 수행되었다.

• 천문학회지
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• 제42권5호
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• pp.107-123
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• 2009

We investigate the wave properties for isothermal plasma state around to the de Sitter black hole's horizon using 3+1 split of spacetime. The corresponding Fourier analyzed perturbed perfect GRMHD equations are used to obtain the complex dispersion relations. We obtain the real values of the wave number k, from these relations, which are used to evaluate the quantities like phase and group velocities etc. These have been analyzed graphically in the neighborhood of the horizon.

• 한국산업융합학회 논문집
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• 제7권1호
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• pp.97-105
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• 2004

The Vapor-liquid equilibrium data for the binary system of 2-methyl-2-propanol-2-butanone are measured at subatmospheric pressure of 100, 200, 300, 400, 500, 600, 700 and 760 torr. This study shows that the relations between logarithmic values of relative valatility(log ${\alpha}$)and liquid phase composition(${\chi}$) in the above binary systems are expressed as a linear function. When the linear relationships of between logarithmic values of relative volatilities and liquid phase compositions in the binary systems of various pressure intersect at a point, this empirical equation can be applied to the systems of this kind. From these relations the vapor-liquid equilibrium data are estimated and compared with the measured values to be in a good agreement with in accuracy ${\pm}0.0021$ for the various pressure.