• 한국생활과학회지
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• 제21권2호
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• pp.377-388
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• 2012

The purpose of this study was to determine the content attributes and sensory characteristics of ice cream flavored with lotus leaf and seeds (Nelumbo nucifera Gaertner). Analysis of freeze dried lotus leaf powder produced the following technical results: Freeze dried lotus leaf powder contained moisture 12.2, crude protein 5.9, crude fat 1.2, crude ash 7.0, crude fiber 13.4g/100mg; raw lotus seed powder contained moisture 65.0, crude protein 8.2, crude fat 0.3, crude ash 1.0, crude fiber 10.8g/100mg; freeze dried lotus seed powder contained moisture 14.0, crude protein 17.1, crude fat 1.9, crude ash 4.0, crude fiber 2.8g/100mg. Lotus seed was processed by 4 methods: freeze dried, roasted, freeze dried peeled inner layer, cooked cut peeled inner layer. Analysis of the color value produced the following technical results: freeze dried lotus leaf powder were L(lightness) 14.5, a(redness) 4.4, b(yellowness) 24.0; freeze dried lotus seed powder L 57.3, a 14.4, b 12.0; roasted lotus seed powder L 52.7, a 22.5, b 11.9; freeze dried lotus seed peeled inner layer L 60.0, a 1.4, b 12.3. Proportional lotus ingredients used for ice cream were 1%, 3%, 5%, 7%, 10% for lotus leaves and 1%, 3%, 5% for lotus seeds. The maximum over run ratio for lotus leaf ice cream was 45.3~56.9% at 20~25 minutes operating time. Over run was significantly decreased by increasing the contents of lotus leaf powder. A maximum over run ratio for lotus seed ice cream was 46.1~54.3% at 20~25 operating time. Over run was not significantly different based on content of lotus leaf versus lotus seed. Sensory evaluation of lotus leaf ice cream produced the following results: the highest score was for color of 4.42 and the lowest score was for sweetness of 3.30. The total mean score significantly decreased by increasing the content of lotus leaf powder. Sensory evaluation of lotus seed ice cream produced the following results: the highest score was for cooked cut peeled inner layer type and the lowest was for freeze dried type 3.86. The sensory scores were not significantly different based on the content of lotus seed. Texture was evaluated highest with a rating of 4.21 and the taste was evaluated lowest with a rating of 3.68 For whole evaluation. This study concluded that lotus leaf ice cream demonstrates relative strength in terms of color and taste, and a relative weakness in terms of over run and sweetness. Suitable content of lotus leaf ranged from 1~5%. The lotus seed processed by the cooked cut peeled inner layer method received a higher rating than dried powder for lotus seed ice cream.

• 설비공학논문집
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• 제10권1호
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• pp.11-21
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• 1998

A numerical study is made on the ice-formation for water flow inside a stenotic tube. The study takes into account the interaction existing between the laminar flow and the stenotic port in the circular tube. In the solution strategy, the present study is substantially distinguished from the existing works In that the complete set of governing equations in both the solid and liquid regions are resolved. In a channel flow between parallel plates, the agreement of predictions and available experimental data is very good. Numerical results are mainly obtained by varying the height and length of a stenotic shape and additionally for several temperatures of the wall and inlet of tube. The results show that the shape of stenotic port has the great effect on the thickness of the solidification layer in the tube. As the height of a stenosis grows and the length of a stenosis decreases, the ice layer thickness near the stenotic port is thinner due to backward flow caused by the sudden expansion of water tunnel. It is also found that the ice layer becomes more fat In accordance with Reynolds number and the temperature of the wall and inlet of tube decreased.

• 한국표면공학회지
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• 제54권5호
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• pp.222-229
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• 2021

Icing causes various serious problems, where water vapor or water droplets adhere at cold conditions. Therefore, understanding of ice adhesion on solid surface and technology to reduce de-icing force are essential for surface finishing of metallic materials used in extreme environments and aircrafts. In this study, we controlled wettability of aluminum alloy using anodic oxidation, hydrophobic coating and lubricant-impregnation. In addition, surface porosity of anodized oxide layer was controlled to realize superhydrophilicity and superhydrophobicity. Then, de-icing force on these surfaces with a wide range of wettability and mobility of water was measured. The results show that the enhanced wettability of hydrophilic surface causes strong adhesion of ice. The hydrophobic coating on the nanoporous anodic oxide layer reduces the adhesion of ice, but the volume expansion of water during the freezing diminishes the effect. The lubricant-impregnated surface shows an extremely low adhesion of ice, since the lubricant inhibits the direct contact between ice and solid surface.

• 설비공학논문집
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• 제9권2호
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• pp.104-111
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• 1997

The freezing phenomenon of saturated water with the supercooled region in a horizontal circular cylinder has been studied experimentally by using the holographic real time interferometry technique. From the experiments, it was found that there were three types of freezing patterns. The first is the annular ice layer growing from the cylinder surface at a high cooling rate; the next is the asymmetric ice layer at a moderate cooling rate; and the last is the instantaneous ice layer growth over the full region at lower cooling rate. As the water was coolde from room temperature to the subfreezing point passing through the density inversion point, the freezing pattern was largely affected by the inversion phenomenon, which had much effected the free convection and was susceptible to influences from the cooling rate. When the cooling rate is high, supercooling energy is released before the water is sufficientry mixed by free convection. On the other hand, when the cooling rate is low, there is much time for the water to be mixed by free convection. This seems to be the reason why the different ice layer growths occur.

• 한국기계가공학회지
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• 제18권12호
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• pp.52-58
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• 2019

This study numerically analyzed the icing process in a U-shaped pipe exposed to the outside by considering the mushy zone of freezing water. Numerical results showed that the flow was pulled outward due to the U-shaped bend in the freezing section exposed to the outside, which resulted in the ice wave formation on the wall of the bended pipe behind. At the same time, the formation of a corrugated ice layer became apparent due to the venturi effect caused by the ice. The factors affecting the freezing were investigated, including the change of the pipe wall temperature, the water inflow velocity, and the pipe bend spacing. It was found that, as a whole, the thickness of the freezing layer increased as the pipe wall temperature decreased. It was also found that the freezing layer became relatively thin when the inflow rate of water was increased, and that the spacing of the pipe bends did not significantly impact the change in the freezing layer.

• 한국태양에너지학회 논문집
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• 제24권1호
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• pp.47-52
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• 2004

An experimental investigation was performed to compare ice making characteristics of ice storage system with smooth and spiral tube. During the freezing processes in the shell and tube type ice storage tank with smooth tube, heat resistance of the ice layer caused a decrease in freezing rate. Also, the phenomena of bridging made the increasing rate of ice making less. In order to improve the ice making rate, spiral tube(pitch=6mm) was used in the present study. The ice making rate and the decreasing of bridging for the spiral tube were higher than those for the smooth tube.

• 대한기계학회논문집B
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• 제21권7호
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• pp.862-872
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• 1997

Ice formation in a horizontal circular cylinder has been studied numerically. From the numerical analysis results, it was found that there were three types of freezing pattern and that freezing phenomenon was affected largely by density inversion and cooling rate. The type of freezing pattern largely depends on the secondary flow which is generated by density inversion. When supercooling energy is released before the development of the secondary flow, the annular ice layer grows. If the energy is released when the secondary flow is considerably developed and the supercooled region is removed to the upper half part of the cylinder, an asymmetric ice layer grows. And if the energy is released after perfect development of the secondary flow, instantaneous dendritic ice formation over the full region occurs. Furthermore, this secondary flow was found to have an effect on heat transfer characteristics. The heat transfer rate becomes small at the instant when the secondary flow is generated, but becomes large with the development of the flow. It's concluded that for the facilitation of heat transfer it is desirable to keep water in liquid phase until the secondary flow is perfectly developed. This study gave an instruction of performance improvement of capsule type ice storage tank.

• Korean Journal of Hydrosciences
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• 제1권
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• pp.61-71
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• 1990

The characteristics of radial thickness of ice jam at the center part of channel bends were analyzed briefly in this paper. Jam thickness in channel bends increases both toward the inner bank, and dowmstream. For this study, slope at the jam's underside was assumed to be liner with similarity of radial slope of bed in alluvial bends. Radial slope at the jam's underside in floating ice elements was estimated using the force equilibrium theory in the radial direction. The eqution which can be estimated the radial slope of ice jam was suggested using Falcon and Kennedy's bed layer theory. Experimental data, which were measured at the center part of cross-section in a single 180-degree bend, were compared to the calculated values using the suggested equtions. The result shows that the calcultated values were smaller than the measured ones. Ot is considered that the estimated value of shear stress in the radial direction may be smaller than the actual and two-layer model may be not suibable for alluvial bend flow.

• 한국해양공학회지
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• 제11권3호
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• pp.144-152
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• 1997

본 논문에서는 1년생 빙맥에 의하여 해양구조물에 작용하는 하중을 추정할 수 있는 모델을 제시하였다. 1년생 빙맥을 수면하부(keel), 수면상부(sail), 경화층(consolidated layer)의 3부분으로 나누어 각 부분에 의한 하중을 추정할 수 있는 방법을 논의하였다. 수면하부는 얼음조각(ice rubble)이 층으로 쌓여져 형성된 것이므로 수면하부에 의한 하중추정을 할 때 얼음조각을 선형 Mohr-Coulomb재료로 생각하여 토질역학(soil mechanics)의 이론을 사용하였다. 수면상부에 의한 하중도 토질역학 이론을 이용하여 추정하였으며 경화층에 의한 하중은 Korzhavin식을 이용하여 추정하였다. 제시한 모델을 이용하여 빙맥하중 추정에 미치는 인자들의 영향을 검토하였다.

• Safety and Health at Work
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• 제10권2호
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• pp.219-223
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• 2019

Background: Ice cooling vests can cause tissue damage and have no flexibility. Therefore, these two undesirable properties of ice cooling vest were optimized, and the present study was aimed to compare the impact of the optimized ice cooling vest and a commercial paraffin cooling vest on physiological and perceptual strain under controlled conditions. Methods: For optimizing, hydrogel was used to increase the flexibility and a layer of the ethylene vinyl acetate foam was placed into the inside layer of packs to prevent tissue damage. Then, 15 men with an optimized ice cooling vest, with a commercial paraffin cooling vest, and without a cooling vest performed tests including exercise on a treadmill (speed of 2.8 km/hr and slope of %0) under hot ($40^{\circ}C$) and dry (40 %) condition for 60 min. The physiological strain index and skin temperature were measured every 5 and 15 minutes, respectively. The heat strain score index and perceptual strain index were also assessed every 15 minutes. Results: The mean values of the physiological and perceptual indices differed significantly between exercise with and without cooling vests (P < 0.05). However, the difference of the mean values of the indices except the value of the skin temperature during the exercises with the commercial paraffin cooling vest and the optimized ice cooling vest was not significant (P > 0.05). Conclusions: The optimized ice cooling vest was as effective as the commercial paraffin cooling vest to control the thermal strain. However, ice has a greater latent heat and less production cost.