• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1093-1099
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• 2009

Alternative energy sources such as renewable energy like solar power systems, wind power systems, or fuel cell power systems has been the rising issue in the electrical power system. This paper discusses an economic study analysis of fuel cells in the korean electricity market. It includes the basic concept of a fuel cell and the korean electricity market. It also describes the need of renewable energy and how the fuel cell is connected with the local grid. This paper shows the impact of production and recovering thermal energy of a grid-connected fuel cell power system. The profit maximization approach has been structured including electrical power trade with the local grid and heat trade within the micro-grid. The strategies are evaluated using a local load that uses electric and thermal power which has different patterns between summer and winter periods. The solution algorithm is not newly developed one, but is solved by an application called GAMS. Results indicate the need and usefulness of a fuel cell power system.

• 한국해양학회지
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• v.24 no.1
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• pp.29-38
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• 1989

It has been believed that the circulation in the Japan Sea involves separation of current from the Korean coast and formation of a cold cyclonic gyre in the north. To explain this, a simple quasi-geostrophic linear model is considered. The model is basically of an inflow-outflow system. The local forcings, wind and air-sea heat exchange together with damping (both mechanical and thermal), are imposed upon. The results show that only the buoyancy damping due to perturbations from local thermal adjustment can cause the separation and the gyre. Various types of circulation patterns are possible depending on the intensity of the thermal forcing.

• Journal of Environmental Health Sciences
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• v.31 no.3
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• pp.215-220
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• 2005

The atmospheric transportation and dispersion processes of air pollutants are important issues in dealing with air pollution problems. Air pollutants originated from biological and anthropogenic activities are not only limited to the local emission sources, but could also be transported and dispersed to other regions by synoptic weather systems. Besides, the complexity of topography of central Taiwan helps accumulating air pollutants to promote high-concentration episodes. The techniques of tethersonding were applied to monitor the vertical profiles of winds, air temperatures and humidity, as well as to collect air samples, to be analyzed for pollutants $(O_3,\;NO_2,\;NO\;and\; NMHC)$ from the ground up to 1000m. A time period of about one week, 19-26 October 2002, was chosen as the sampling period due to the high frequency of episode occurrence in autumn based on the past records. Associating with the analysis of weather patterns, the atmospheric characteristics over high-concentration areas can be resolved in more detail. The result of the tethersonding studies showed that weak northerly sea breeze (with thickness about 300m) with low wind speed (about 1 to 2 m/sec) could help develop high ozone concentrations in the down-wind areas. It is also important to have a built-up aloft of precursors and ozone to develop high concentration on the previous day.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.184-210
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• 2005

The atmospheric transportation and dispersion processes of air pollutants are important issues in dealing with air pollution problems. Air pollutants originated from biological and anthropogenic activities are not only limited to the local emission sources, but could also be transported and dispersed to other regions by synoptic weather systems. Besides, the complexity of topography of central Taiwan helps accumulating air pollutants to promote high-concentration episodes. The techniques of tethersonding were applied to monitor the vertical profiles of winds, air temperatures and humidity, as well as to collect air samples, to be analyzed for pollutants ($O_3,\;NO_2$, NO and NMHC) from the ground up to 1000 m. A time period of about one week, 19 -26 October 2002, was chosen as the sampling period due to the high frequency of episode occurrence in autumn based on the past records. Associating with the analysis of weather patterns, the atmospheric characteristics over high-concentration areas can be resolved in more detail. The result of the tethersonding studies showed that weak northerly sea breeze (with thickness about 300 m) with now wind speed (about 1 to 2 m/sec) could help develop high ozone concentrations in the down-wind areas. It is also important to have a built-up aloft of precursors and ozone to develop high concentration on the previous day.

• Journal of the Korea Society for Simulation
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• v.22 no.2
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• pp.101-107
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• 2013

Because forest fires are predicted to increase in severity and frequency under global climate change with important environmental implications, an understanding of fire dynamics is critical for mitigation of these negative effects. For the reason, researchers with different background, such as ecologists, physicists, and mathematical biologists, have developed the simulation models to mimic the forest fire spread patterns. In this study, we suggested a novel model considering the wind effect. Our theoretical forest was comprised of two different tree species with varying probabilities of transferring fire that were randomly distributed in space at densities ranging from 0.0 (low) to 1.0 (high). We then studied the distributional patterns of burnt trees using a two-dimensional stochastic cellular automata model with minimized local rules. We investigated the time, T, that the number of burnt trees reaches 25% of the whole trees for different values of the initial tree density, fire transition probability, and the degree of wind strength. Simulation results showed that the values of T decreased with the increase of tree density, and the wind effect decreased in the case of too high or low tree density. We believe that our model can be a useful tool to explore forest fire spreading patterns.

• Journal of the Korean earth science society
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• v.39 no.4
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• pp.327-341
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• 2018

Extreme temperatures and precipitations are expected to be more frequently occurring due to the ongoing global warming over the Korean Peninsula. However, few studies have analyzed the synoptic weather patterns associated with extreme events in a warming world. Here, the atmospheric patterns related to future extreme events are first analyzed using the HadGEM3-RA regional climate model. Simulations showed that the variability of temperature and precipitation will increase in the future (2051-2100) compared to the present (1981-2005), accompanying the more frequent occurrence of extreme events. Warm advection from East China and lower latitudes, a stagnant anticyclone, and local foehn wind are responsible for the extreme temperature (daily T>$38^{\circ}C$) episodes in Korea. The extreme precipitation cases (>$500mm\;day^{-1}$) were mainly caused by mid-latitude cyclones approaching the Korean Peninsula, along with the enhanced Changma front by supplying water vapor into the East China Sea. These future synoptic-scale features are similar to those of present extreme events. Therefore, our results suggest that, in order to accurately understand future extreme events, we should consider not only the effects of anthropogenic greenhouse gases or aerosol increases, but also small-scale topographic conditions and the internal variations of climate systems.

• Fire Science and Engineering
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• v.28 no.6
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• pp.13-21
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• 2014

Forest fire has a number of variables and since the effects of wind fields are bigger than any other variables, it is essential to know wind direction and velocity for the forest fire extinguishing techniques and the prediction of fire spread. With regards to the local area that has a high chance of forest fire, the data from meteorological observatory in the area is used for the estimation of wind velocity. It is relatively easy to obtain automatic weather station (AWS) data which are available for the whole nation. There is a chance that the data from the weather station may be different with the actual data at the mountain areas. In this study simply shaped hills (Sae-byeol hill of Jeju Island and port Ma-geum in An-myeon Island in the sea side) were selected as the experimental locations to minimize the distortion of the wind field by the adjacent geographic features. Spot measurements and analysis of computational fluid dynamics (CFD) for the given geographic features were conducted to examine and compare their consistency. As a conclusion It is possible to predict wind patterns in these simple locations.

• Journal of the Korean association of regional geographers
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• v.22 no.2
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• pp.450-465
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• 2016

The purpose of this study is to examine the spatial characteristics of relationships between the intensity of extreme climate events driven by typhoons and the magnitude of economic damages at local municipality scales across the Republic of Korea for the recent 15-year period (2000~2014). As results, it is observed that the intensity of extreme temperature events such as heavy rainfall and gusty wind accounts for 50% of the damages magnitude across Korea, while the correlation between the two at the Si-Gun municipality level regionally varies. Positive correlations between the intensity of heavy rainfall events and typhoon damages are observed in the southeastern regions of Taebaek-Sobaek mountain ridges, while such statistically-significant patterns are not detected in the northwestern region. In contrast, statistically-significant positive correlations between the strength of gusty winds and damages are found in most of regions except for some interior regions and northeastern mountainous regions. Classification maps of major extreme climate event types (heavy rainfall-prevailing type, gusty wind-prevailing type, and their combined type) leading to typhoon damages at the Si-Gun municipality scales provided in this study may help local administrations to make the optimized policies for typhoon damage mitigation.

• Journal of the Korean earth science society
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• v.30 no.4
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• pp.464-477
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• 2009

In this study, we examined the patterns of local circulation over the Daechung lake area through the numerical experiment designed to investigate the impact of lake on the local circulation. The results of numerical experiment showed that the surface temperature predicted by WRF model was lower than the observation, while the wind speed was stronger than the observation. The local circulation over the lake area was characterized by a lake breeze induced by a horizontal thermal contrast between the lake surface and the Surrounding land. At Daecheong Lake, a lake breeze formed at 09 LST and dissipated at 18 LST, with maximum intensity at 15 LST. The vertical extent of the simulated circulation was about 1,200 m. The specific humidity increased as the humid air above the lake moved landward due to the daytime circulation of the lake breeze. The numerical experiments of sensitivity to existence of the lake showed that the simulated surface temperature decreased in the experiment with the lake. Wind speed was more intense around the lake area when the actual land use was substituted by grassland land use. The results of numerical experiments suggest that the lake-induced lake breeze circulation has an effect on the meteorology of planetary boundary layer around the lake.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.2
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• pp.142-158
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• 2012

This paper investigates the physical and chemical characteristics of long-range transport (LRT) process of air pollutants by employing the MM5-CMAQ and its comparison with local emission dominant (LED) case over northeast Asia. We first classified high air pollution days into LRT and LED cases based on the synoptic meteorological variables of vorticity and geostrophic wind speed/direction at a geopotential level of over 850hPa. LRT cases are further categorized into three types of transport patterns (LRT-I-III) according to the air mass pathways from source regions. LRT-I-III are originated from northern, central, and southern China, respectively, identified by back trajectory analysis. Three LRT-I-III groups have different and unique locations of high pressure and transport pathways. The chemical characteristics showed that the simulated spatial distributions varied in terms of locations of maximum concentrations and the temporal variation of surface concentrations. The primary air pollutants such as $NO_x$, $PM_{10}$ and $SO_2$ of all of three LRT cases are well transported into Korea peninsula with different concentration levels. Of LRT cases, LRT-II has the greatest effect on air quality of Korea peninsula, followed by LRT-I and LRT-III. In comparison with LRT, the LED case shows relatively higher air pollution concentrations in general, but showed a variety of different air quality levels following the emission strength pattern. These widely varying patterns are impling the case dependent multi-directional approach for the development of indicators of long-range transport process over northeast Asia.