• Food Engineering Progress
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• v.14 no.2
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• pp.92-98
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• 2010

In this study, various active functional components in Chinese Quince were extracted by solvent extraction method. A central composit design for optimization was applied to investigate the effects of independent variables such as solvent to sample ratio ($X_{1}$), extraction temperature ($X_{2}$), and extraction time ($X_{3}$) on the soluble solid contents ($Y_{1}$), total phenols ($Y_{2}$), electron donating ability ($Y_{3}$), browning color ($Y_{4}$) and reducing sugar contents ($Y_{5}$). It was found that extraction temperature and extraction time were the main effective factors in this extraction process. The maximum soluble solid contents of 35.77% was obtained at 26.38 mL/g ($X_{1}$), 72.82$^{\circ}C$ ($X_{2}$) and 74.86 min ($X_{3}$) in saddle point. Total phenols were rarely affected by solvent ratio and extraction time, but it was affected by extraction temperature. The maximum total phenols of 20.70% was obtained at 22.61 mL/g ($X_{1}$), 84.49$^{\circ}C$ ($X_{2}$), 77.25 min ($X_{3}$) in saddle point. The electron donating ability was affected by extraction time. The maximum electron donating ability of 94.12% was obtained at 10.65 mL/g ($X_{1}$), 67.78$^{\circ}C$ ($X_{2}$), 96.75 min ($X_{3}$) in saddle point. The maximum browning color of 0.32% was obtained at 23.77 mL/g ($X_{1}$), 87.27$^{\circ}C$ ($X_{2}$), 96.68 min ($X_{3}$) in saddle point. The maximum value of reducing sugar content of 10.55% was obtained at 26.83 mL/g ($X_{1}$), 82.167$^{\circ}C$ ($X_{2}$), 81.94 min ($X_{3}$). Reducing sugar content was affected by extraction time.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.1
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• pp.8-13
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• 1997

An electric field due to point dipole within conductor-backed thin dielectric layer above the earth is calculated by using saddle point method When the dielectric layer is thin enough to support a cutoff mdoe, we show that the field may be approximated by sum of contributions of branch points of TE mode and poles of tM mode and that the branch points and poles contributions are interpreted as an evanescent lateral waves and leaky waves, respectively.

• Journal of the Korean Mathematical Society
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• v.54 no.2
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• pp.663-673
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• 2017

We consider the multi-harmonic model for the bubble evolution in the Rayleigh-Taylor instability in two and three dimensions. We extend the multi-harmonic model in two dimensions to a high-order and present a new class of steady-state solutions of the bubble motion. The growth rate of the bubble is expressed by a continuous family of two free parameters. The critical point in the family of solutions is identified as a saddle point and is chosen as the physically significant solution. We also present the multi-harmonic model in the cylindrical geometry and find the steady-state solution of the axisymmetric bubble. Validity and limitation of the model are also discussed.

• ETRI Journal
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• v.35 no.2
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• pp.218-225
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• 2013

The pull-out frequency of a second-order phase lock loop (PLL) is an important parameter that quantifies the loop's ability to stay frequency locked under abrupt changes in the reference input frequency. In most cases, this must be determined numerically or approximated using asymptotic techniques, both of which require special knowledge, skills, and tools. An approximating formula is derived analytically for computing the pull-out frequency for a second-order Type II PLL that employs a sinusoidal characteristic phase detector. The pull-out frequency of such PLLs can be easily approximated to satisfactory accuracy with this formula using a modern scientific calculator.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1078-1082
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• 1997

The distance in load parameter space to the closest voltage collapse point provides the worst case power margin and the left eigenvector identifies the most effective direction to steer the system to maximize voltage stability under contingency. This paper presents the results of the comparative performance study of the algorithms, which are applicable to a large scale power system, for computing the closest saddle node bifurcation (CSNB) point. Dobson's iterative method converges with robustness. However the slow process of updating the load increasing direction makes the algorithm less efficient. The direct method converges very quickly. But it diverges if the initial guess is not very close to CSNB. Zeng's method of estimating the approximate critical point in the pre-determined direction is attractive in the sense that it uses only using load flow equations. However, the method is found to be less efficient than Dobson's iterative method. It may be concluded from the above observation that the direct method with the initial values obtained by carrying out the iterative method twice is most efficient at this time and more efficient algorithms are needed for on-line application.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.8
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• pp.951-957
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• 1999

The saddle node bifurcation (SNB) and the distance voltage instability are valuable information in power system planning and operation. This paper presents a new efficient, robust and unified strategy to compute the SNB by the combined use of the continuation power flow (CPF), Point of Collapse (PoC) method, and the method of a pair of multiple load flow solutions (PMLFS) with Lagrange interpolation utilizing only their advantages: the approximate nose curves and critical loading are determined fast by Lagrange-interpolating two stable and two unstable solutions obtained by using the robust CPF and PMLFS; the exact SNB is computed by the quadratically converging PoC method. The proposed method has been tested on Klos-Kerner 11-bus, New England 30-bus, IEEE 118-bus and KEPCO 791-bus systems. The method is found to be so efficient that computation time for determining the SNB of the KEPCO 791-bus system is 17.82 sec by a notebook PC with 300 MHz Pentium processor.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.220-223
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• 2008

Large curved plate blocks are widely used to construct hull structure in shipbuilding industry. Most curved plates are manufactured by using manual method called as line heating that use deformation caused by residual stress after local heating along a line which is perpendicular to the curvature direction. However, its working environment is poor and its formability is totally dependent on an experienced technician. In view of that, multi-point dieless forming (MDF) technology that use reconfigurable punch arrays instead of one piece die is proposed in this study. The MDF process is based on a concept of equivalent die surface made by numbers of punches which has round tip at the end of it. In this study, numerical simulation for common curvature type such as saddle shape was carried out. In addition, experiments in the plate forming process were also conducted to compare with the numerical results in view of final configuration. Consequently, it was noted that the proposed dieless forming method has considerable feasibility to substitute the new process for conventional manual method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.4
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• pp.653-657
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• 2002

The hydrolysis conditions (enzym $e_strate ratio, time and temperature) of the mixture of anchovy sauce residue (ASR) and soy sauce residue (SSR) after fermentation by Flavourzyme 500M $G^{TM}$ were optimized using response surface methodology (RSM) for pretreatment of processing functional enzyme-hydrolyzed sauce. A model equation obtained from RSM was hydrolysis ratio (%) = 28.157+1.929enzym $e_strate ratio+1.818time+2.038temperature-1.093temperatur $e^2$, whose stationary point showed saddle point. From the ridge analysis of the saddle point, the conditions producing the highest hydrolysis ratio was determined as follows: 0.49% enzym $e_strate ratio; 3.55hr hydrolysis time; 62.5$^{\circ}C$ hydrolysis temperature. Adding of SSR to the mixture of water and ASR improved sensory qualities of mixture, so it seemed that SSR has masking effects on off-flavor and taste of ASR.R.of ASR.R.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.349-352
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• 2006

The conventional segregated finite element formulation produces a small and simple matrix at each step than in an integrated formulation. And the memory and cost requirements of computations are significantly reduced because the pressure equation for the mass conservation of the Navier-Stokes equations is constructed only once if the mesh is fixed. However, segregated finite element formulation solves Poisson equation of elliptic type so that it always needs a pressure boundary condition along a boundary even when physical information on pressure is not provided. On the other hand, the conventional integrated finite element formulation in which the governing equations are simultaneously treated has an advantage over a segregated formulation in the sense that it can give a more robust convergence behavior because all variables are implicitly combined. Further it needs a very small number of iterations to achieve convergence. However, the saddle-paint-type matrix (SPTM) in the integrated formulation is assembled and preconditioned every time step, so that it needs a large memory and computing time. Therefore, we newly proposed the P2PI semi-segregation formulation. In order to utilize the fact that the pressure equation is assembled and preconditioned only once in the segregated finite element formulation, a fixed symmetric SPTM has been obtained for the continuity constraint of the present semi-segregation finite element formulation. The momentum equation in the semi-segregation finite element formulation will be separated from the continuity equation so that the saddle-point-type matrix is assembled and preconditioned only once during the whole computation as long as the mesh does not change. For a comparison of the CPU time, accuracy and condition number between the two methods, they have been applied to the well-known benchmark problem. It is shown that the newly proposed semi-segregation finite element formulation performs better than the conventional integrated finite element formulation in terms of the computation time.

• The Korean Journal of Food And Nutrition
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• v.6 no.3
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• pp.178-188
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• 1993

This research was attempted to investigate changes in physicochemical properties of rice extrudate with added ginger powder extruded by single screw extruder. Graphic three dimensional analysis on response surface regression was used to evaluate effects of extrusion variables on quality factors of the extrudate according to two independent variables, ginger consent 0∼12%, moisture content 14∼26%. The summarized results are as follows : 1) Regarding proximate composition of rice extrudate with added ginger powder, as ginger powder content of raw material Increased, crude tat, crude protein, crude ash and crude fiber increased, while soluble nitrogen free extract decreased. 2) Graphic three dimensional analysis on response surface regression was conducted for each dependent variable which revealed statistically significant relationship with independent variables, 0∼120A ginger and 14∼26% moisture content. Expansion ratio had a critical point as moisture content changed. As ginger and moisture content Increased, bulk density, break strength and water absorption Index Increased, while water solubility Index decreased. The predicted maximum degree of gelatinization in 6.15% ginger and 15.56% moisture content is 88.27%, and lightness decreased as ginger content Increased. According to the microstructure for the cross section of extrudate obsorbed with image analyzer, air cell number and perimeter revealed saddle point, meanwhile total area and fractarea of air cell had critical points as moisture content changed. In view of the results, quality of rice extrudate with added ginger powder was optimum when rice flour was fed to the extruder with 2∼7% singer powder and 15∼20% moisture content.