• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.12
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• pp.1763-1773
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• 1998

In the present experimental study, the flow behavior in a semi-closed two-phase natural circulation loop was examined. Water was used as the working fluid. Heat flux, heater-inlet subcooling, and flow restrictions at the heater-inlet and at the expansion-tank-line were taken as the controlling parameters Six circulation modes were identified by changing heat flux and inlet subcooling conditions ; single-phase continuous circulation, periodic circulation (A), two-phase continuous circulation, and periodic circulations (B), (C), and (D). Among these, the single-phase and two-phase continuous-circulation modes exhibit no significant oscillations and are considered to be stable. Periodic circulation (A) is characterized by the large amplitude two-phase f10w oscillations with the temporal single-phase circulation between them, while periodic circulation (B) featured by the flow oscillations with continuous boiling inside the heater section. Periodic circulation (C) appears to be the manometric oscillation with continuous boiling. Periodic circulation (D) has the longer period than periodic circulation (B) and a substantial amount of liquid flow back and forth through the expansion-tank-line periodically ; this mode is considered the pressure drop oscillation. Parametric study shows that the increases of the inlet- and expansion-tank-line- restrictions and the decrease of inlet subcooling broaden the range of the stable two-phase(continuous circulation) mode.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.77-84
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• 2010

This paper presents the continuous commissioning process, information on the case study facility, improved system operation, and building energy consumption measures before and after continuous commissioning implementation. Continuous commissioning is an ongoing process to resolve operating problems, improve comfort, optimize energy use and identify retrofits for existing commercial and institutional buildings and central plant facilities. Continuous commissioning process consists of two phases. The first phase is the project development phase and the second phase implements and verifies project performance. Results of a case study show that continuous commissioning implementation can reduce energy costs. The energy reports show the electricity savings of 22% and gas savings of 47% on an average.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.7
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• pp.29-35
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• 1994

The performance of continuous phase modulation signals is well known for the coherent demodulation. But the carrier recovery circuits of the coherent receiver have long acquisition time and the receiver experiences high error floors for fading channels. In this paper, we propose the differential demodulation of 2-h continuous phase modulation signals. The sets of modulation indices of 2-h phase codes adequate to the differential demodulation for differentially encoded input are obtained and the average bit error probability in Additive White Gaussian Noise environments is derived and analyzed.

• Journal of Sericultural and Entomological Science
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• v.40 no.2
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• pp.169-175
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• 1998

The morphology of silk fibroin/poly(vinyl alcohol)(PVA)blend films was investigated using optical microscopy and confocal laser scanning microscopy. The effects of blend ratio and molecular weight of silk fibroin and PVA on phase separation were studied. Macro-phase separation occurred for the silk fibroin-rich/poor region whereas micro-phase separation took place for the dispersed/continuous phase, In spite of differences in molecular weight and blend ratio, it is observed that the dispersed phase and continuous one are composed of silk fibroin and PVA component, respectively. As the molecular weight of silk fibroin and silk fibroin content in blend ratio are decreased, the compatibility of blend is increased due to the reduction of micro-phase separation.

• Journal of Industrial Technology
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• v.18
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• pp.267-275
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• 1998

Continuous thermodynamics has been applied for modeling of phase equilibria in multicomponent mixtures, to avoid disadvantages of the pseudo-component and key-component method. In this paper continuous thermodynamic relations formulated by using the Pate-Teja equation of state were adopted for calculations of phase equilibria in natural gas mixtures, crude oil mixtures and mixtures extracted by supercritical $CO_2$ fluids. Calculations of phase equilibria were performed by two procedures ; a moment method coupled with the beta distribution function and a quadrature method combined with Gaussian-Legendre polynomials. Calculated results were compared with experimental data. It was showed that continuous thermodynamic frameworks considered in this paper were well-matched to experimental data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.811-818
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• 2016

A continuous fine-tuning phase locked loop with an additional negative feedback loop has been proposed. When the phase locked loop is out-of-lock, the phase locked loop has a fast locking characteristic using the continuous band-selection loop. When the phase locked loop is near in-lock, the bandwidth is narrowed with the fine loop. The additional negative feedback loop consists of a voltage controlled oscillator, a frequency voltage converter and its internal loop filter. It serves a negative feedback function to the main phase locked loop, and improves the phase noise characteristics and the stability of the proposed phase locked loop. The additional negative feedback loop makes the continuous fine-tuning loop work stably without any voltage fluctuation in the loop filter. Measurement results of the fabricated phase locked loop in $0.18{\mu}m$ CMOS process show that the phase noise is -109.6dBc/Hz at 2MHz offset from 742.8MHz carrier frequency.

• Journal of Industrial Technology
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• v.15
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• pp.123-135
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• 1995

In this paper, we performed the modeling of a tunable three section DFB-LD with continuous phase using the coupled-wave equation. It was also proposed new modeling method for ${\lambda}/4$ phase shifted one. We got the characteristics of oscillation wavelength, gain, and photon density profiles according to parameters such as coupling coefficient K and current into the third sections for two case of continuous phase and ${\lambda}/4$ shifted phase one. The simulations for ${\lambda}/4$ phase shifted tunable three section DFB-LD prove that the continuous tuning range is about 4.2nm for $K=120cm^{-1}$, $L=180{\mu}m$, and the oscillation mode be within the stop-bands. Also when changed a current of both end sections, it is shown that a photon density reaches the maximum at the center.

• Journal of the Korean Society of Safety
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• v.8 no.2
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• pp.44-50
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• 1993

The objective of this study was to investigate the extraction of chromium(Vl) ion in waste water through the liquid surfactant membrane with open-type Perforated Reciprocating-Plate Column. Extraction experiments were conducted to measure the effect of flow characteristics of continuous and dispersed phase and stroke velocity, sodium hydroxide concentraction in internal aqueous phase, sulfuric acid concentraction in outer phase, and residence time distribution and measured extraction velocity. The result of experiments showed that extraction velocity of chromium ion was maximum when stroke velocity was 180 1/min and dispersion phase velocity was 30m11min, continuous phase velocity was 20m1/min. Extraction velocity of chromium ion increased with increasing difference of hydrogen ion concentraction of dispersion and continuous phase and column stage decreased.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.770-774
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• 2002

Effect of surfactant micelles on lipid oxidation was determined in soybean oil-in-water (O/W) emulsions. The concentration of ferric irons to continuous phase in the O/W emulsions was measured as a function of various Brij type and concentrations. The concentration of ferric iron in the continuous phase increased with increasing surfactant micelles concentration $(0.5{\sim}2.0%)$ and storage time $(1{\sim}7\;days)$. At pH 3.0, the concentration of continuous phase iron was higher than at pH 7.0. Lipid oxidation rates, as determined by the formation of lipid hydroperoxides and headspace hexanal, in the O/W emulsions containing ferric iron decreased with increasing surfactant micelle concentration $(0.5{\sim}2.0%)$. These results indicate that surfactant micelles concentration could alter the physical location and prooxidant activity of iron in soybean O/W emulsions.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.243-248
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed. A two-fluid three-field model was adopted for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. The hydrodynamic solver is for the 3D component of a nuclear system code and the component-scale analysis tools for transient two-phase flows. The finite volume method and unstructured grid are adopted, which are useful for the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing problems well.