• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.2
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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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.144-150
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• 2018

In this study, the freezing process of L-shaped pipe exposed to the outside was investigated numerically by considering the mushy zone of freezing water. From the numerical results, it was found that the flow was outwardly directed due to the influence of the L-shaped bending part in the outside exposed part of the pipe, and the ice was formed in the shape of longitudinal corrugation on the wall surface of the pipe after the bending part. It is confirmed that this phenomenon is caused by the venturi effect due to the freezing as seen in connection with the velocity distribution in the pipe. It is found that the remelting phenomenon at the end of the freezing section occur simultaneously during the process of forming the ice in the pipe section. In regard of the factors affecting freezing, it was found that the thickness of the freezing layer is increased as the exposed pipe surface temperature is decreased, and the pipe surface temperature had a significant effect on the change of the freezing layer thickness. At the same time, it was found that the freezing layer becomes relatively thin when the water inflow rate is increased. This phenomenon was caused by reducing the exposure time of freezing water due to the vigorous flow convection of the water fluid.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.7
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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.

• Journal of The Korean Association For Science Education
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• v.25 no.2
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• pp.88-97
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• 2005

The purpose of this study was to investigate explanations of science textbooks and science teachers' conceptions related to freezing point depression phenomenon. Seven kinds of middle school science textbooks and five kinds of high school chemistryII textbooks were analyzed for the purpose. The teachers' conceptions were searched by a questionnaire developed in this study. The subjects were 146 science teachers. The explanation types of science textbooks were divided into two; 'Description of the phenomenon' and 'Vapor pressure lowering'. The explanations in most of middle school science textbooks and high school chemistryII textbooks belong to 'Description of the phenomenon' and there was no explanation of the reason. The graphs related to depression of freezing point were diverse, too. Most of the science teachers also did not have scientific conception. The percentage of the teachers who thought that the cause of freezing point depression was blocking of solute in solution was high. But the teacher could not find meaningful relation the 'Blocking of solute' explanation represented for elevation of boiling point with depression of freezing point. It is insisted that entropy concept is need to explain depression of freezing point phenomenon in this study.

• Journal of Korean Elementary Science Education
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• v.32 no.2
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• pp.206-224
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• 2013

The purpose of this study is to investigate the elementary pre-service teachers' conceptions on 'the freezing point depression' focusing on the survey from a National University of Education. Eighteen pre-service teachers who had completed high school Chemistry II coursework were selected to participate in the study. Participants answered a four question survey to measure their scientific knowledge and conceptions of this phenomenon. Each answer was qualitatively analyzed to determine whether they have 'scientific conceptions' or 'quasi-scientific conceptions' or 'misconceptions'. The results from the study are as follows: First, it was showed that none of the eighteen participants had 'scientific conceptions', six had 'quasi-scientific conceptions' and eight had 'misconceptions' about the caused effect when $CaCl_2$ is scattered on the ice. Second, it was found that three participants had 'scientific conceptions', eight had 'quasi-scientific conceptions' and two had 'misconceptions' for the second survey question. Third, ten out of eighteen participants demonstrated 'scientific conceptions' about the phenomenon of salt water freezing. Fourth, only three of eighteen participants illustrated appropriate 'scientific conceptions' for the fourth survey question. Fifth, of all participants, none answered more than three questions correctly, and only three participants answered any combination of two questions correctly. Based on the findings of this study, five explanatory models were developed. And the models were proposed for pre-service teachers to enhance their understanding of the freezing point depression phenomenon.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.3
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• pp.275-283
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• 1999

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.6 no.1
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• pp.17-22
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• 2010

A sliding accident on the road have a high percentage by road freezing, especially, it is often appeared at bridges and tunnel of freezing areas. Thus, the stability of road operations is enhanced by preventing a partial freezing phenomenon. According to the geothermal snow melting system analysis, a pattern of thermal conductivity is found out about pavement materials of concrete and asphalt when it is buried. For the feasibility study on geothermal snow melting system, analysis of the ground melting point when operating system, life evaluation of pavements and safety evaluation of pipes are performed.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.106-111
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• 2013

In this study, numerical simulations and performance evaluation has been carried out to investigate performance characteristics of air-type high pressure piston pump. ANSYS and CFX were applied for analyzing the structure and flow behavior of air-type high pressure piston pump, respectively. The performance evaluation of high pressure piston pump was performed experimentally, the results were compared with simulation. It was found that the freezing phenomenon was improved by 20% and the pressure fluctuation decreased by 50%, compared with the previous pump.

• Journal of the Korean association of regional geographers
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• v.7 no.1
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• pp.97-106
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• 2001

There are a few interesting areas which show freezing during summer season in Korea, three of them are especially important. They are located at Milyang(Gyungnam province), Uisung and Chungsong(Gyungbook province). They are named Eoleumgol(ice-valley) or Binghyul(ice-cave). The purpose of this study is to clarify geomorphological and geological characteristics about the distribution areas of freezing during summer season in Korea in relation to previous works, which have been studied in hydrological or micro-climatological viewpoints. The main results are summarized as follows. 1) The main geomorphological and geological characteristics in the distribution areas of freezing during summer season (1) Thick debris accumulated slope within deep valley (2) North facing slope (3) The component debris of volcanic rock such as andesite or rhyolite 2) The ice-cave as a system that give rise to freezing phenomenon in summer season is closely related to talus slope. The ice-cave has thick accumulated debris and lots of vacant spaces within the rock deposits, some of vacant spaces are very big and connected with underground water system. 3) A partly freezing within underground water system is required freezing phenomenon in summer season. Judging from this point of view, two ideas are suggested; one is the evaporation theory, another is that the frozen condition in winter remains untill late summer.

• Journal of Environmental Science International
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• v.26 no.7
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• pp.827-836
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• 2017

Freezing rain is a phenomenon when precipitation falls as a liquid rain drop, but freezes when it comes into contact with surfaces or objects. In this study, we investigated the predictability of freezing rain and its characteristics, which are strongly related with the occurrence of black ice using synoptic scale meteorological observation data. Two different cases occurred at 2012 were analyzed and in the presented cases, freezing rain often occurs in the low-level low pressure with the warm front. The warm front due to the lower cyclone make suitable environment in which snow falling from the upper layer can change into supercooled water. The $0^{\circ}C$ temperature line to generate supercooling water is located at an altitude of 850 hPa in the vertical temperature distribution. And the ground temperature remained below zero, as is commonly known as a condition for black ice formation. It is confirmed that the formation rate of freezing rain is higher when the thickness after 1000-850 hPa is 1290-1310 m and the thickness of 850-700 hPa layer is larger than 1540 m in both cases. It can also be used to predict and estimate the generation of freezing rain by detecting and analyzing bright bands in radar observation.