• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.225.1-225
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• 2003

잣을 이용한 쌀가루즉석죽 제조조건의 최적화와 제조조건에 따른 관능적 특성을 4차원 반응표면분석에 의하여 모니터링 하였다. 죽의 제조에 이용되는 잣은 가루같이 으깬 것을 첨가하는 것이 바람직하였다. 관능적 특성에 의한 잣죽의 점성에 대한 최적조건은 주입액의 양과 잣의 첨가비율이 각각 쌀가루 무게의 15.52배, 16%, 가열조리시간 7.79 분이었으며 이때 $R^2$는 0.9518, 관능평점은 7.45, 임계점은 maximum point였다. 색상에 대한 최적조건은 19.09배, 45%, 2.16분($R^2$=0.7917)이었고 관능평점은 5.44, saddle point였으며, 맛에 대한 최적조건은 12.90배, 22%, 11.40분($R^2$=0.9361), 관능평점은 7.11, maximum point였고, 향에 대한 최적조건은 15.06배, 20%, 4.9분($R^2$=0.8372), 관능평점은 6.16, saddle point였다. 관능적 특성을 모두 만족시켜주는 최적조건은 주입액의 양과 잣의 첨가비율이 각각 쌀가루무게의 16.86배와 15%, 가열조리시간 5.48분이었고 이때 $R^2$는 0.9738, 관능적 평점은 7.69, 임계점은 maximum point였다. 관능적 특성 중 점성은 맛과 전반적기호도에 큰 영향을 주었으며 상관계수는 각각 0.8173($R^2$=0.0001), 0.7878($R^2$=0.0002)이었고 맛은 향과 전반적인 기호도와 밀접한 관계가 있으며 상관계수는 각각 0.5196($R^2$=0.0325)과 0.7004($R^2$=0.0017)이었다.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.791-798
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• 1994

Ohmic heating is a food processing operation in which heat is internally generated within foods by the passage of alternating electric current. The process enables highly viscous paste foods such as Kochujang, and fermented soybean paste to be heated very fast. In order to develope the novel pasteurization process of paste foods, static Ohmic heating system was built, and heating characteristic during Ohmic heating under various conditions were studied. Electric conductivities of Kochujang and fermented soybean paste at room temperature were 1.865 S/m and 2.510 S/m, respectively and increased linearly with increasing temperature. Specific heating rate was highly dependent on the frequency. The highest heating rate was achieved at 5 KHz for Kochujang and 20 KHz for fermented soybean paste. Uniform heating throughout the sample was achieved during Ohmic heating with low frequency electrical currents, however above 5 KHz frequency, surface temperature was several degrees higher than the bulk.

• Journal of Drive and Control
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• v.11 no.1
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• pp.8-13
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• 2014

Hydraulic servo valves are widely used in various fluid power systems because of their fast response and precision control. In this paper, we studied the effect of metering notch shapes and amount of their openings on the flow characteristics within the spool valve using a computational fluid dynamic (CFD) code, FLUENT. To obtain the results for more realistic operating conditions, viscous heating due to the jet flow and viscosity variation of the hydraulic fluid with temperature were considered. For two types of notch shape, streamlines, oil temperature and viscosity distributions, and variations of flow and friction forces acting on spool were showed. The flow and friction forces affected by the metering notch shapes and their openings, and oil temperature rise near metering notch was significant enough to results in the jamming phenomenon. A thermohydrodynamic (THD) flow analysis adopted in this paper can be used in optimum design of hydraulic servo valves.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.4
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• pp.325-330
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• 2000

Alginate obtained from brown algae had various physicochemical and rheological properties and could used as a dietary fiber, However, alginate has not been widely applied to the food industry, since it had high viscosity, high gelling effect conjugated with some mineral, and low solubility. To improve functionality of alginate, partially develymerized alginates, which was water-soluble dietary fiber were obtained by hydrolysis of alginate from the sea tangle, Laminaria japonicus, heated at $121^{\circ}C$. Effects of depolymerization of alginate on the changes of viscosity and average molecular weight, block composition ratio of mannuronate to guluronate (M/G ratio), chemical properties using $PT-IR, ^1H-NMR, and ^(13)C-NMR$ spectrum were investigated. The average molecular weight and viscosity of the alginate were rapidly decreased with the thermal decomposition, and estimated to be 1,307,415 dalton and 284,000 cps, before heating, 728,106 and 3,940.29 cps after 30 min heating, 102,635 and 22.22 cps after 2.5 hrs heating, 51,205 and 12.05 cps after 3 hrs, and 10,049 and 4.28 cps after 6.5 hrs, respectively. The M/G ratio was increased with the heating time, while MM-block did not show any changes and GG-block diminished. The results of $FT-IR, ^1H-NMR and ^(13)C-NMR$ spectrum suggested that changes of molecular structure did not occur by the thermal decomposition.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.569-573
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• 1998

This study was conducted to investigate the differences of textural characteristics and microstructure of sugared chestnuts between heated by a heater and microwave. Raw chestnuts were boiled and infiltrated the sugar in sugar syrup by heating. The content of WSP (water soluble pectin) was increased, but HSP (hydrochloric acid soluble pectin) was decreased by boiling and sugaring. This change was remarkable when it was boiled and sugared by a microwave heating. The hardness, gumminess and chewiness were more decreased in the sugared chestnut boiled and sugared with a microwave than that processed with a heater. Microstructure of sugared chestnut processed with a microwave heating showed the distruction of cell wall.

• Journal of Ginseng Research
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• v.32 no.3
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• pp.238-243
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• 2008

Comparison of the physico-chemical characteristics were investigated among white (WG), fermented (FG) and red ginseng (RG) extracts. We observed maximum contents of extractable solids in FG, but viscosity was lower than other ginseng extracts. The contents of ash and crude protein of FG were higher than those of other ginseng extracts. The contents of carbohydrate were similar, but component Na and cruid lipids were maximum in RG. we extended our study on comparison of the calories among WG, FG and RG. We noticed that comparison of the calories among WG, FG and RG showed insignificant difference.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.80-86
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• 2005

This study presents numerical solutions of the two-dimensional Navier-Stokes equations for supersonic unsteady flow in a convergent-divergent nozzle with heat addition. The TVD scheme in generalized coordinates is employed in order to calculate the moving shock waves caused by thermal choking. We discuss on transient characteristics, start and unstart phenomena, fluctuations of specific thrust caused by thermal choking and viscous effects. We prove that the control of separation of boundary layer is the most important key problem to prevent the thermal choking.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.4
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• pp.489-498
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• 1988

An analysis has been given for the effect of viscous dissipation on the thermal instability of plane Couette flow between two parallel plates maintained at different constant temperatures. Under the assumption that the principle of the exchange of stabilities holds, stationary disturbance quantities in the form of longitudinal vortices are considered. The magnitudes of disturbance quantities are then represented as fast convergent power series so that the eigenvalue problem for determining the onset conditions of the thermal instability may be reduced to a simplified problem of finding the roots of a $4{\times}4$ determinant. It is shown that as the magnitude of the visucous dissipation increases the flow becomes more susceptible to instabilities, which is in very good agreement with previous results obtained in some related researches.

• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.594-597
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• 2004

Effects of various levels and molecular weights (MWs) of chitooligosaccharides and chitosan with pork salt-soluble protein (SSP) on pH, moisture (%), viscosity, and hardness of protein-chitosan mixtures were determined in a model study. Mixtures of 0.15, 0.3, and 0.45% chitosan at various MWs (Low, 1.5 kDa; Medium, 30-50 kDa; High, 200 kDa) were dissolved in 3% SSP solution for measurement of pH and viscosity at $20^{\circ}C$. pH value increased with addition of 0.45% low MW of chitooligosacchearides into SSP (p<0.05), whereas decreased with addition of 0.45% medium MW and 0.3% or higher level of high MW chitosan. Viscosity increased with addition of more than 0.3% either medium or high MW chitosan (p<0.05), as compared to mixture with low MW chitolligosaccharide and control (p<0.05). No differences in gel pH, moisture, and hardness values were observed among treatments (p>0.05). Further study will be performed to evaluate rheological properties actual meat products with various levels and MWs of chitosan.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.103-109
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• 1994

Changes in the rheological properties and the linear viscoelasticity of fish protein gel upon the thermal processing were studied by using mathematical models with stress-relaxation data. The linear viscoelasticity of surimi gel was observed in the range of the true strain $0.105{\sim}0.693$ and cross-head speed $50{\sim}250\;mm/min$ applied in this study. The results of the generalized Maxwell analysis showed that the magnitudes of elastic elements $(E,\;E_e)$ were increased, but the viscous element $({\eta}) $was decreased, as the cross-head speeds and strain levels were increased. Compared to the protein gel heated directly at $90^{\circ}C$ without preheating, the protein gel pretreated at $4^{\circ}C$ and $40^{\circ}C$ showed the higher elastic modulus, but showed different trends in the viscous component, depending on the rheological model applied. Thus, the approaching methods and curve fitting of two mathematical models of stress-relaxation to describe the viscoelastic properties of fish protein gel were discussed.