• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.38-47
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• 1999

An improved one-dimensional modeling of snow melting was obtained by considering both the effect of heat capacity and the decreasing influence of porosity. Using the improved model, the effects of initial snow temperature, initial snow density and the heat flux on the snow melting were investigated. It is found that the drainage starting time is delayed and the drainage rate becomes smaller with lower initial snow temperature. ResuIts also show that the drainage starts at the same time when an initial snow density is over a certain value. Melting efficiency increases linearly with an increasing initial snow temperature. With increasing the initial density of the snow and the amount of heat supplied, the melting efficiency increases, then converges to a constant value.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.6
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• pp.599-608
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• 2000

One dimensional numerical modeling was carried out for the melting behavior of dry snow and the unsaturated flow when heat was supplied from the bottom surface. Discrepancy between the previous experimental data and the present numerical results is substantially reduced by considering the density change of water permeation layer due to the infiltration of meltwater. In the parametric study for effective thermal conductivity, it was found that the effect of this parameter to the behavior of snow melting is minor. Sensitivity analysis showed that the melting time is most sensitive to changes in supplied heat flux, snow temperature, and bulk density, whereas snow bulk density and residual saturation have a significant effect on the height of water permeation layer in snow.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.2
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• pp.92-101
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• 2020

To prevent and mitigate damage to farms due to heavy snowfall, snow weight information should be provided in addition to snow depth. This study reviews four formulae regarding snow density and weight used in extant studies and applies them in Suwon area to estimate snow weight in Korea. We investigated the observed snow depth of 94 meteorological stations and automatic weather stations (AWS) data over the past 30 years (1988-2017). Based on the spatial distribution of snow depth by area in Korea, much of the fresh snow cover, due to heavy snowfall, occurred in Jeollabuk-do and Gangwon-do. Record snowfalls occurred in Gyeongsangbuk-do and Gangwon-do. However, the most recent heavy snowfall in winter occurred in Gyeonggi-do, Gyeongsangbuk-do, and Jeollanam-do. This implies that even if the snow depth is high, there is no significant damage unless the snow weight is high. The estimation of snow weight in Suwon area yielded different results based on the calculation method of snow density. In general, high snow depth is associated with heavy snow weight. However, maximum snow weight and maximum snow depth do not necessarily occur on the same day. The result of this study can be utilized to estimate the snow weight at other locations in Korea and to carry out snow weight prediction based on a numerical model. Snow weight information is expected to aid in establishing standards for greenhouse design and to reduce the economic losses incurred by farms.

• Journal of Environmental Science International
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• v.18 no.3
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• pp.255-261
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• 2009

We need water equivalent unit data of snowfall for the purpose of forecast and hydrology related research area. This study developed new method of automatic recording snowfall as weight unit. The instrument designed for measuring weight of snowfall by stain-gauge loadcell. Field test of instrument carried out at Daegwallyeong Obs. Station from 22 Jan. to 22 Feb. 2007. During observation period there is 15.3 cm snow depth and 16.0 mm of accumulated water equivalent depth at Daegwallyeong Obs. Station on 13 to 14 Feb. 2007. But the instrument of this study recorded 22.1 mm of water equivalent depth. It is not easy to explain difference between Daegwallyeong and this study. Because this study is only one case of comparison of snow measurement and there is very little amount of snow observation research. The density of snowfall calculated from 0.09 to $0.15g/cm^3$ from the observation data of 13 to 14 Feb. 2007. There is high relation between radar echo and snowfall amount measured by weight unit. It can supports forecast of snowfall and development of numerical model for forecast.

• Atmosphere
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• v.19 no.1
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• pp.1-8
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• 2009

We need water equivalent unit data of snowfall for the purpose of forecast and hydrology related research area. This study developed new method of automatic recording snowfall as weight unit with circle type plate using stain-gauge loadcell. Field test of instrument carried out at Daegwallyeong Obs. Station from 20 to 23 Jan. 2008 during heavy snowfall. There is 74.2cm snow depth and 54.6mm precipitation by Daegwallyeong Obs. Station. But the instrument of this study recorded 71.0mm of precipitation amount. Because of different observation method can cause more 15.4mm than Daegwallyeong Obs. Station. But this study gives the possibility of observation of new snow fall measurement under freezing conditions of snow. From the observation data the density of snowfall calculated from 0.09 to $1015g/cm_3$ from the observation period. And have a good relations between manual observation and automatic observation data from this study instrument with slope of 1.35 to 1.39.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.3
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• pp.151-156
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• 2009

This study shows that the distribution density of snow crab, Chionoecetes opilio, was estimated using an underwater video monitoring system attached on the towing sledge. The field experiments were carried out at the coastal waters around Chuksan, East Sea, where ranged from 110 to 130m depth during September and October 2007. The sledge was towed for 40 minutes and the towing speed was controlled between 1.5 to 1.7 knot and each research areas were calculated to multiply towed distance by the detection width of the video monitoring system(1.2m), and then, distribution density of snow crab in each observations were estimated as a counted number of crab per 1,000$m^2$. The result shows that their survey, taken between two months, reflected similar results during survey period, and the maximum and mean distribution densities in September estimated to be 77.0(number/1,000$m^2$) and 19.9, respectively, and those of October were 36.0 and 21.8, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.2
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• pp.75-84
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• 2021

As the weather changes become frequent, weather disasters are increasing, causing more damage to plastic greenhouses. Among the damage caused by various disasters, damage by snow to the greenhouse takes a relatively long time, so if an alarm system is properly prepared, the damage can be reduced. Existing greenhouse design standards and snow warning systems are based on snow depth. However, even in the same depth, the load on the greenhouse varies depending on meteorological characteristics and snow density. Therefore, this study aims to secure the structural safety of greenhouses by developing sensors that can directly measure snow loads, and analysing the warning criteria for load using a stochastic model. Markov chain was applied to estimate the failure probability of various types of greenhouses in various regions, which let users actively cope with heavy snowfall by selecting an appropriate time to respond. Although it was hard to predict the precise snow depth or amounts, it could successfully assess the risk of structures by directly detecting the snow load using the developed sensor.

• Journal of Korean Society of Transportation
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• v.31 no.6
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• pp.3-11
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• 2013

Under the consumption of bad weather situation affects traffic flows, the study scope is focused on highway capacity and speed variations among other highway traffic flow characteristic changes according to snowfall density. Thus, this study carried out through the data collection and statistical analysis by focusing on capacity and speed changes. Traffic volume, speed and density were selected as factors to explain the property change of a traffic flow for analysis, and 7 basic sections such as 3 highways in Gyeonggi-do and 4 highways near the meteorological observatory were selected as survey points for data collection. Snowfall levels were classified into 3 steps(Light, Medium, Heavy Snow) to analyze the capacity change by snowfall levels. As a result of analysis, the change of capacity depending on snowfall levels decreased 13.2% in case of light snow compared to a good weather, 18.6% in case of medium snow and 32.0% in case of heavy snow, so the capacity reduction rate increased as the snowfall level increased. The worsening weather appeared to have a very big possibility to act as a factor to reduce the operational efficiency of a road, so a road design and operation method considering this should be presented in the future.

• Wind and Structures
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• v.3 no.2
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• pp.73-81
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• 2000

Snowdrifts around buildings can cause serious problems when formed on undesirable places. The formation of snowdrifts is highly connected to the wind pattern around the building, and the wind pattern is again dependent on the building design. The shear stress on the surface and snowdrifting around different buildings are investigated through CFD analysis and compared to measurements. The computations of shear stress shows local minima in the same areas as snowdrifts are formed. The snowdrifting computations utilises a drift-flux model where a fluid with snow properties is allowed to drift through a fluid with air properties. An apparent dynamic viscosity of the snow/air mixture is defined and used as a threshold criterion for snowdrifting. The results from the snowdrifting computations show increased snow density where snowdrifts are expected, and are in agreement with previous large-scale snowdrift measurements. The results show that computational fluid dynamics can be a tool for planning building design in snowdrifting areas.

• Journal of Korea Water Resources Association
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• v.52 no.9
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• pp.627-635
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• 2019

In Korea, snow damage has been happened in the region with no snowfalls in history. Also, casual damage was caused by heavy snow. Therefore, policy about the Natural Disaster Reduction Comprehensive Plan has been changed to include the mitigation measures of snow damage. However, since heavy snow damage was not frequent, studies on snowfall have not been conducted in different points. The characteristics of snow data commonly are not same to the rainfall data. For example, some parts of the southern coastal areas are snowless during the year, so there is often no values or zero values among the annual maximum daily snow accumulation. The characteristics of this type of data is similar to the censored data. Indeed, Busan observation sites have more than 36% of no data or zero data. Despite of the different characteristics, the frequency analysis for snow data has been implemented according to the procedures for rainfall data. The frequency analysis could be implemented in both way to include the zero data or exclude the zero data. The fitness of both results would not be high enough to represent the real data shape. Therefore, in this study, a methodology for selecting a probability density function was suggested considering the characteristics of snow data in Korea. A method to select probability density function using conditional joint probability distribution was proposed. As a result, fitness from the proposed method was higher than the conventional methods. This shows that the conventional methods (includes 0 or excludes 0) overestimated snow depth. The results of this study can affect the design standards of buildings and also contribute to the establishment of measures to reduce snow damage.