• Horticultural Science & Technology
• /
• v.32 no.4
• /
• pp.493-498
• /
• 2014

The objective of this study was to make growth and yield models for common ice plant (Mesembryanthemum crystallinum L.) using expolinear functional equations in a closed-type plant production system. Three-band radiation type fluorescent lamps with a 12-hours photoperiod were used, and the light intensity was $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Nutrient film systems with three layers were used for plant growth. Environmental conditions, such as air temperature, relative humidity and $CO_2$ concentration were controlled by an ON/OFF operation. Leaf area, shoot fresh and dry weights, light use efficiency of common ice plant as function of days after transplanting, accumulative temperature and accumulative radiation were analyzed. Leaf area, shoot fresh and dry weights per area were described using an expolinear equation. A linear relationship between shoot dry and fresh weights was observed. Light use efficiency of common ice plant was $3.3g{\cdot}MJ^{-1}$ at 30 days after transplanting. It is concluded that the expolinear growth model can be a useful tool for quantifying the growth and yield of common ice plant in a closed plant production system.

• Atmosphere
• /
• v.25 no.1
• /
• pp.155-167
• /
• 2015

A dynamical seasonal prediction system for boreal winter utilizing cryospheric information was developed. Using the Community Atmospheric Model, version3, (CAM3) as a modeling system, newly developed snow depth initialization method and sea ice concentration treatment were implemented to the seasonal prediction system. Daily snow depth analysis field was scaled in order to prevent climate drift problem before initializing model's snow fields and distributed to the model snow-depth layers. To maximize predictability gain from land surface, we applied one-month-long training procedure to the prediction system, which adjusts soil moisture and soil temperature to the imposed snow depth. The sea ice concentration over the Arctic region for prediction period was prescribed with an anomaly-persistent method that considers seasonality of sea ice. Ensemble hindcast experiments starting at 1st of November for the period 1999~2000 were performed and the predictability gain from the imposed cryospheric informations were tested. Large potential predictability gain from the snow information was obtained over large part of high-latitude and of mid-latitude land as a result of strengthened land-atmosphere interaction in the modeling system. Large-scale atmospheric circulation responses associated with the sea ice concentration anomalies were main contributor to the predictability gain.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.4
• /
• pp.255-262
• /
• 2016

Effects of $SiO_x$ or C shells on electrochemical properties of Si nanoparticles were investigated. $SiO_x$ shells with thickness of 10~15 nm were formed on homogeneously crystalline Si nanoparticles. Incase of Si-C nanoparticles, there were 30~40 layers of C with a number of defects. Li-ion batteries were fabricated with the above-mentioned nanoparticles, and their electrochemical properties were measured. Pristine Si shows a high IRC (initial reversible capacity) of 2,517 mAh/g and ICE (initial columbic efficiency) of 87%, but low capacity retention of 22%, respectively. $SiO_x$ shells decreased IRC (1,534 mAh/g) and ICE (54%), while the retention increased up to 65%, which can be explained by irreversible phases such as $LiO_2$ and $Li_2SiO_3$. C shells exhibited no differences in IRC and ICE compared to the pristine Si but an enhanced retention of 54%, which might be from proper defect structures.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.6
• /
• pp.801-809
• /
• 2019

NASA's lunar polar exploration mission in 2009 confirmed the presence of ice-layer in the permanently shadowed regions (PSR) of the moon. Since then, studies have been actively conducted to evaluate the ground characteristics for exploring the ice-layer in the polar regions of the Moon. In this study, transient heat transfer analysis for the lunar ground was conducted to predict the ground's temperature that varies with the time and location. As a result of the numerical analysis, it was confirmed that the temperature under the lunar ground converged to below the ice sublimation reference temperature (≒112 K) at above 86° latitude. This model enabled us to identify the regions where there is a high possibility of ice being buried. Besides, we found that the ice-layer in the shallow region, where the temperature deviation is significant, makes ground temperature distribution heterogeneous. Lastly, this study suggested the maximum allowable frictional heat of a drill bit that can preserve the phase of buried ice.

• Ocean and Polar Research
• /
• v.36 no.1
• /
• pp.13-24
• /
• 2014

We established the first complete ice core processing method and analytical procedures for fundamental proxies, using a 40.2 m long ice core drilled on the Mt. Tsambagarav glacier in the Mongolian Altai mountains in July 2008. The whole core was first divided into two sub ice core sections and the measurements of the visual stratigraphy and electrical conductivity were performed on the surface of these sub core sections. A continuous sequence of samples was then prepared for chemical analyses (stable isotope ratios of oxygen ($^{18}O/^{16}O$) and hydrogen ($^2H/^1H$), soluble ions and trace elements). A total of 29 insoluble dust layers were identified from the measurement of visual stratigraphy. The electrical conductivity measurement (ECM) shows 11 peaks with the current more than 0.8 ${\mu}A$ Comparing the profiles of $SO_4{^{2-}}$ and $Cl^-$ concentrations to correlate with known volcanic eruptions, the first two ECM peaks appear to be linked to the eruptions (January and June 2007) of Kliuchevskoi volcano on the Kamchatka Peninsula of Russia, which supports the reliability of our ECM data. Finally, the composition of stable isotopes (${\delta}^{18}O$ and ${\delta}D$) shows a well-defined seasonal variation, suggesting that various chemical proxies may have been well preserved in the successive ice layers of Tsambagarav ice core. Our ice core processing method and analytical procedures for fundamental proxies are expected to be used for paleoclimate and paleoenvironmental studies from polar and alpine ice cores.

• Journal of the Korean earth science society
• /
• v.41 no.1
• /
• pp.31-39
• /
• 2020

Cheonji, the largest caldera lake in Asia, is located at the summit of Baekdu Mountain. Cheonji is covered with snow and ice for about six months of the year due to its high altitude and its surrounding environment. Since most of the sources of water are from groundwater, the water temperature is closely related to the volcanic activity. However, in the 2000s, many volcanic activities have been monitored on the mountain. In this study, we analyzed the dimension of ice produced during winter in Baekdu Mountain using Sentinel-1 satellite image data provided by the European Space Agency (ESA). In order to calculate the dimension of ice from the backscatter image of the Sentinel-1 satellite, 20 Gray-Level Co-occurrence Matrix (GLCM) layers were generated from two polarization images using texture analysis. The method used in calculating the area was utilized with the Support Vector Machine (SVM) algorithm to classify the GLCM layer which is to calculate the dimension of ice in the image. Also, the calculated area was correlated with temperature data obtained from Samjiyeon weather station. This study could be used as a basis for suggesting an alternative to the new method of calculating the area of ice before using a long-term time series analysis on a full scale.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.1
• /
• pp.114-120
• /
• 2020

In this study, the process of freezing around two consecutively arranged channel tubes used for evaporator heat exchange was numerically investigated. Numerical results confirmed that the vortex occurred between the front channel and the rear channel and also that the vortex occurred due to the rapid change of the channel at the rear of the rear channel. These vortices were found to play a role in reducing the ice layer to some extent by the growth of the ice layer at the front and rear of the channel tube. The freezing layer showed a tendency to gradually increase as it passed through the channel pipe. As the wall temperature in the channel pipe decreased, the thickness of the freezing layer increased. As the flow rate of water slowed, the thickness of the freezing layer became thicker. In particular, in the case of a slow flow rate of 0.03 m/s, the freezing layers of the front channel pipe and the rear channel pipe were connected to each other. The narrower the channel, the thinner the freezing layer was in both the front and rear channel tubes. It is found that these thin freezing layers are caused by the low thickness of the temperature boundary layer formed around the channel tube.

• International Journal of Highway Engineering
• /
• v.17 no.5
• /
• pp.1-10
• /
• 2015

PURPOSES : A finite difference model considering snow melting process on porous asphalt pavement was derived on the basis of heat transfer and mass transfer theories. The derived model can be applied to predict the region where black-ice develops, as well as to predict temperature profile of pavement systems where a de-icing system is installed. In addition, the model can be used to determined the minimum energy required to melt the ice formed on the pavement. METHODS : The snow on the porous asphalt pavement, whose porosity must be considered in thermal analysis, is divided into several layers such as dry snow layer, saturated snow layer, water+pavement surface, pavement surface, and sublayer. The mass balance and heat balance equations are derived to describe conductive, convective, radiative, and latent transfer of heat and mass in each layer. The finite differential method is used to implement the derived equations, boundary conditions, and the testing method to determine the thermal properties are suggested for each layer. RESULTS: The finite differential equations that describe the icing and deicing on pavements are derived, and we have presented them in our work. The framework to develop a temperature-forecasting model is successfully created. CONCLUSIONS : We conclude by successfully creating framework for the finite difference model based on the heat and mass transfer theories. To complete implementation, laboratory tests required to be performed.

• The Bulletin of The Korean Astronomical Society
• /
• v.39 no.1
• /
• pp.67.1-67.1
• /
• 2014

Comets are mysterious travelers from outer Solar System. It is considered that comets loose their subsurface ice once they were injected into a snow-line of the solar system, at the same time, develop adiathermic dust layers on the surface in a time scale of ~10,000 years. They eventually become inactive (see also the presentation by Yoonyoung Kim et al.). Optical similarity between comets and asteroids in comet-like orbits suggests the existence of such dormant or inactive comets supporting the evolutionary scenario. However, unforeseen accidents cast a misgiving to modify the stereotype. A periodic comet, 17P/Holmes, is known as comet with very low activity before 2007. However, the comet suddenly exhibited an outburst in 2007 October, which is known as the most energetic cometary outburst since the beginning of modern astronomy. On the other hand, another periodic comet, P/2010 V1, was not known before 2010 November probably because of low activity and discovered while it experienced outburst. We investigated the time-evolution of the magnitudes and the morphological developments based on the dynamical theory of dust grains, and derived the energy per unit mass of ~10,000 J/kg. From these observational evidences, we suggest that crystallization of buried amorphous ice (even in low-activity comets) can be responsible for the dramatic cometary outbursts.

• Horticultural Science & Technology
• /
• v.34 no.2
• /
• pp.236-241
• /
• 2016

The common ice plant (Mesembryanthemum crystallinum L.) has some medicinal uses and recommended plant in closed-type plant factory. The objective of this study was to estimate the cardinal temperatures for seed germination of the common ice plant using bilinear, parabolic, and beta distribution models. Seeds of the common ice plant were germinated in the dark in a growth chamber at four constant temperatures: 16, 20, 24, and $28^{\circ}C$. For this, four replicates of 100 seeds were placed on two layers of filter paper in a 9-cm petri dish and radicle emergence of 0.1 mm was scored as germination. The times to 50% germination were 4.3, 2.5, 2.0, and 1.8 days at 16, 20, 24, and $28^{\circ}C$, respectively, indicating that the germination of this warm-weather crop increased with temperature. Next, the time course of germination was modeled using a logistic function. For the selection of an accurate model, seeds were germinated in the dark at constant temperatures of 6, 12, 32, and $36^{\circ}C$. Germination started earlier and increased rapidly at temperatures above $20^{\circ}C$. The minimum, optimal, and maximum temperatures were estimated by regression of the inverse of time to 50% germination rate, as a function of the temperature gradient. The different functions estimated differing minimum, optimal and maximum temperatures, with 5.7, 27.7, and $36.5^{\circ}C$, respectively for the bilinear function, 13.4, 25.0, and $36.6^{\circ}C$, respectively, for the parabolic function and 7.8, 25.9, and $36.0^{\circ}C$, respectively, for the beta distribution function. The models estimated that the inverse of time to 50% germination rate was 0 at 6 and $36^{\circ}C$. The observed final germination rates at 12 and $32^{\circ}C$ were 62 and 97%, respectively. Our data show that a beta distribution function provides a useful model for estimating the cardinal temperatures for germination of seed from the common ice plant.