• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.74-79
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• 2006

Good cold start characteristics are essential for satisfactory operation of fuel cell vehicles. In this study, the melting process has been numerically investigated for a water tank frozen in cold weather The 2-D model of the tank containing ice and plate heaters was assumed and the unsteady melting process of the ice was calculated. The enthalpy method was used for the description of the melting process, and a FVM code was used to solve the problem. The feasibility study compared with other experiment showed that the developed program was able to describe the melting process well. From the numerical analysis carried out for different wall temperatures of the pate heaters, some important design factors could be found such as local overheating and pressurization in the tank.

• Journal of the Korean Chemical Society
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• v.8 no.2
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• pp.68-74
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• 1964

Water has the melting point, the boiling point, the heat of fusion, and the heat of vaporization all much higher than would be normally expected from the hydrogen compounds of the other members of the oxygen family. Another unique characteristic of ice-Ⅰ is its volume decrease which takes place in its melting. A number of significant efforts have been made in the past to explain these properties quantitatively. The authors, reasoning from the unusually great free surface energy of water and the characteristic volume change on melting, propose the structural model of liquid water as follows. On melting, fluidized vacancies of a molecular size are introduced. Thereupon, for the unusually great surface energy density, molecules surrounding the vacancies become to have close packed arrangement. But molecules not in direct contact with vacancies should still possess the original structure i. e., ice-Ⅰ. When a molecule adjacent to a vacancy jumps into the vacancy, the molecule attains the gaslike degree of freedom. Using the above model, the authors had developed the liquid partition function of water by applying the theory of significant structures in liquids. Molar volume, vapor pressure, entropy of fusion and entropy of vaporization were calculated over a wide temperature range. The results show good agreement with experimental observations.

• Atmosphere
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• v.29 no.4
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• pp.367-380
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• 2019

Global warming causes various problems such as the increase of the sea surface temperature, the change of coastlines, ocean acidification and sea level rise. Sea level rise is an especially critical threat to coastal regions where massive population and infrastructure reside. Sea level change is affected by thermal expansion and mass increase. This study projected future sea level changes in the 21st century using the HadGEM2-AO with RCP8.5 scenario. In particular, sea level change due to water mass input from ice-sheets and glaciers melting is studied. Sea level based on surface mass balance of Greenland ice-sheet and Antarctica ice-sheet rose 0.045 m and -0.053 m over the period 1986~2005 to 2081~2100. During the same period, sea level owing to dynamical change on Greenland ice-sheet and Antarctica ice-sheet rose 0.055 m and 0.03 m, respectively. Additionally, glaciers melting results in 0.145 m sea level rise. Although most of the projected sea level changes from HadGEM2-AO are slightly smaller than those from 21 ensemble data of CMIP5, both results are significantly consistent each other within 90% uncertainty range of CMIP5.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2009.04a
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• pp.95-100
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• 2009

Global warming melts polar ice, changes ocean currents, creates variation of local climate, and inundates low-altitude regions resulting in disasters to mankind. Accordingly, developed countries including U.S.A. and U.K. spend great amounts of efforts and money to plan and manage research activities on polar ice which is regarded as a key indicator of climate change. The proposed research aims to provide basic information for chasing and monitoring the melting phenomena of polar ice through multiple GPS to enhance the GPS quality.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.10
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• pp.2595-2606
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• 1995

Buoyancy-assisted melting of an unconstrained ice in an isothermally heated horizontal enclosure was numerically analyzed in a range of wall temperatures encompassing the density inversion point. The problem as posed here involves two physically distinct domains each of which has its own scales and respective heat transfer mode. These two domains join at the junction where the liquid squeezed out of the film region flushes into the lower melt pool. Both of these domains have been treated separately in the literature by a patching technique which invokes several, otherwise unnecessary, assumptions. The present study eliminates successfully such a superfluous procedure by treating the film and lower melt pool regions as a single domain. As a result of this efficient solution procedure, the interaction of the water stream ejected at the junction and the natural convection in the melt pool could be clarified for different wall temperatures. Though limited by two-dimensionality, the present results conformed indirectly the earlier reported transition of the flow pattern, as the wall temperature was increased over the density inversion point. The transient evolution of the melting surface, the time rate of change in melt volume fraction, the local and temporal variation of the heat transfer coefficients are analyzed and presented.

• Food Science and Biotechnology
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• v.15 no.5
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• pp.721-727
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• 2006

This study was carried out to investigate the effect of hydrocolloids on the changes in physical properties of a model ice cream. The model ice cream contained water, sugar, skin milk powder, com oil, and 4 different hydrocolloid stabilizers (gelatin, pectin, hydroxyethylstarch, locust bean gum), was manufactured in a batch type freezer. The following physical characteristics of ice cream were examined: flow behavior, overrun, air cell size, ice crystal size, and melt resistance. With regard to flow behavior, all of aged mixes had a lower apparent viscosity relative to the mix before aging, and ice cream mix containing locust bean gum had the highest viscosity. Air cell size was observed to range from 20 to $38\;{\mu}m$, and ice cream with locust bean gum showed the largest size. There was an inverse correlation between overrun and air cell size. The ice crystal sizes of all samples ranged from 25 to $35\;{\mu}m$. Ice cream with added pectin contained the smallest ice crystal size, which was significantly difference from other stabilizers (p<0.05), and resulted in superior melt resistance with increased melting time compared to other samples.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.432-437
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• 2019

The objective of this study was to determine the molecular/crystalline structures and phase transition properties of starches isolated from six rice cultivars grown in Korea. Apparent amylose content was highest in starch obtained from the Saemimyeon cultivar (30.8%) and lowest in that obtained from the Sheonhyangheukmi cultivar (20.3%). Starch from the Saemimyeon cultivar had a lower proportion of short chains (DP 6-12) and a the higher proportion of long chains (DP${\geq}37$) than that seen in other rice starches. Saemimyeon had relatively higher pasting temperature ($86.5^{\circ}C$), gelatinization temperature ($72.1^{\circ}C$) and gelatinization enthalpy (14.2 J/g) than these values found for other rice starches. The onset temperature and enthalpy for ice crystallization of rice starch ranged from $-27.1{\sim}-20.2^{\circ}C$ and 241.1~264.8 J/g, respectively. The ice melting enthalpy measured in excess water (67% water content) of rice starches was 282.4~310.1 J/g. Among the rice starches examined, starch obtained from Sheonhyangheukmi, with the lowest amylose content, showed the lowest glass transition temperature (${T_g}^{\prime}$).

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.130-135
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• 2000

To enhance heat transfer characteristics of water, fine ice was added to it. The convective heat transfer characteristics of the ice slurry were investigated in a flow loop with a constant heat flux test section. The Nusselt number and Fanning friction coefficient of water flow were found to be similar to the expected curve by Petukhov. The Nusselt number of the ice sin flow was higher than the Nusselt number of water. Effective thermal capacity of the 10.84% ice slurry was found to have 2.39 times of the thermal capacity of water.

• Journal of the Korean Chemical Society
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• v.62 no.2
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• pp.106-112
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• 2018

Ice-binding proteins have an affinity for ice. They create a gap between the melting and freezing points by inhibiting the growth of ice, known as thermal hysteresis (TH). Interestingly, moderately active LeIBP and hyperactive FfIBP are almost identical in primary and tertiary structures, but differ in TH activity. The TH of FfIBP is tenfold higher than that of LeIBP, due to a subtle difference in their ice-binding motifs. To further evaluate the difference in TH, the interactions were investigated by ice-etching and molecular docking. Ice-etching showed that FfIBP binds to the primary and secondary prism, pyramidal, and basal planes; previously, LeIBP was found to bind to the basal and primary prism planes. Docking analysis using shape complementarity (Sc) showed that the hyperactive FfIBP had higher Sc values for all four ice planes than LeIBP, which is comparable with TH. Docking can be used to describe the hyperactivity of IBPs.

• Korean Journal of Remote Sensing
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• v.37 no.1
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• pp.1-11
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• 2021

This study measures the change of ice flow velocity of David Glacier, one of the fast-moving glaciers in East Antarctica that drains through Drygalski Ice Tongue. In order to effectively observe the rapid flow velocity, we applied the offset tracking technique to Sentinel-1A SAR images obtained from 2016 to 2020 with 36-day temporal baseline. The resulting velocity maps were averaged and the two relatively fast points (A1 and A2) were selected for further time-series analysis. The flow velocity increased during the Antarctic summer (around December to March) over the four years' observation period probably due to the ice surface melting and reduced friction on the ice bottom. Bedmap2 showed that the fast flow velocities at A1 and A2 are associated with a sharp decrease in the ice surface and bottom elevation so that ice volumetric cross-section narrows down and the crevasses are being created on the ice surface. The local maxima in standard deviation of ice velocity, S1 and S2, showed random temporal fluctuation due to the rotational ice swirls causing error in offset tracking method. It is suggested that more robust offset tracking method is necessary to incorporate rotational motion.