• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.210-224
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• 1996

The SLODSVAT consists of interrelated submodels that simulate : the transfer of radiation, water vapour, sensible heat, carbon dioxide and momentum in two canopy layers determined by environmental conditions and ecophysiological properties of the vegetation ; uptake and storage of water in the "root-stem-leaf" system of plants ; interception of rainfall by the canopy layers and infiltration and storage of rain water in the four soil layers. A comparison of the results of modeling experiments and field micro-climatic observations in a spruce forest(Picea abies [L].Karst) in the Soiling hills(Germany) shows, that the SLODSVAT can describe and simulate the short-term(diurnal) as well as the long-term(seasonal) variability of water vapour and sensible heat fluxes adequately to natural processes under different environmental conditions. It proves that it is possible to estimate and predict the transpiration and evapotranspiration rates for spruce forest ecosystems on the patch and landscape scales for one vegetation period, if certain meteorological, botanical and hydrological information for the structure of the atmospheric boundary layer, the canopy and the soil are available.

• Journal of Korean Society of Disaster and Security
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• v.16 no.3
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• pp.1-15
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• 2023

This study focuses on modeling the impact of ammonia leakage from the storage tank in a combined cycle power plant's flue gas denitrification facility. It employs accident impact assessments and diffusion models to determine the optimal scenarios for ammonia storage tank leakage accidents. The study considers the operating conditions of variables as standard conditions for predicting the extent of damage. The Taean combined cycle power plant is chosen as the target area, taking into account seasonal factors such as temperature, humidity, wind speed, atmospheric stability, and wind direction. By utilizing a Gaussian diffusion model, the concentration of ammonia gas at various locations is estimated to assess the potential extent of external damage resulting from a leak. The study reveals that in conditions of high temperature and stable atmosphere within the specified range, lower wind speeds contribute to increased damage to the human body due to ammonia diffusion.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.425-436
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• 2015

The carbon cycle came into the spotlight due to the climate change and forests are well-known for their capacity to store carbon amongst other terrestrial ecosystems. The annual organic carbon of litter production, forest floor litter layer, soil, aboveground and belowground part of plant, standing biomass, net primary production, uptake of organic carbon, soil respiration, etc. were measured in Mt. Worak in order to understand the production and carbon budget of Quercus serrata forest that are widely spread in the central and southern part of the Korean Peninsula. The total amount of organic carbon of Q. serrata forest during the study period (2010-2013) was 130.745 ton C ha^-1. The aboveground part of plant, belowground part of plant, forest floor litter layer, and organic carbon in soil was 50.041, 12.510, 4.075, and 64.119 ton C ha^-1, respectively. The total average of carbon fixation in plants from photosynthesis was 4.935 ton C ha^-1 yr^-1 and organic carbon released from soil respiration to microbial respiration was 3.972 ton C ha^-1 yr^-1. As a result, the net ecosystem production of Q. serrata forest estimated from carbon fixation and soil respiration was 0.963 ton C ha^-1 yr^-1. Therefore, it seems that Q. serrata forest can act as a sink that absorbs carbon from the atmosphere. The carbon uptake of Q. serrata forest was highest in stem of the plant and the research site had young forest which had many trees with small diameter at breast height (DBH). Consequentially, it seems that active matter production and vigorous carbon dioxide assimilation occurred in Q. serrata forest and these results have proven to be effective for Q. serrata forest to play a role as carbon storage and NEP.

• Tunnel and Underground Space
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• v.2 no.1
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• pp.116-122
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• 1992

A comprehensive, nonsteady state, computer simulation program for the environmental conditions in advancing tunnels (the HEADSIM simulation program) is constructed and successfully validated with heat balance amongst all heat sources, and with mass conservation amongst various airflows including the leakage air from ducts, under timedependent variations of inlet air conditions. which include sudden, diurnal and seasonal changes. Heat conduction in the wall strata and face strata is simulated with most complicated boundary conditions using the finite difference method, and the climatic conditions in roadway sections which contain air ducts, booster fan, spray cooler, compressed air pipes, cold water pipes, return water pipes, machinery and broken rock are simulated taking into account the variations of face operation and the heat storage mechanism in the strata. The limitations of simulation time steps and roadway section lengths are defined according to the stability criteria satisfying the principles of thermodynamics. Variations of heat transfer coefficients, which are newly set, and those of wetness factors are taken into account according to the variations of other parameters and the stepwise advance of the face. Newly-derived formulae are used for computing the air duct leakage and the pressure inside of the duct. A new concept of an 'imaginary duct' is introduced to simulate the climatic conditions in tunnels during holiday periods, which directly affect conditions on subsequent working days under the consideration of natural convection. A subsidiary program (the WALLSIM simulation program) is made to compute the dimensionless tunnel surface temperatures and to compare the results with those from analytical approaches, and to demonstrate the stability, convergence and accuracy of the strata heat conduction simulation, adopting the finite difference method. The WALLSIM also has wide applications, including those for the computation of age coefficients.

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.993-1001
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• 2017

Drought is a worldwide natural disaster with extensively adverse impacts on natural ecosystems, agricultural products, social communities and regional economy. Various global satellite observations, including SMAP soil moisture, GRACE terrestrial water storage, Terra and Aqua vegetation productivity, evapotranspiration, and satellite precipitation measures are currently used to characterize seasonal timing and inter-annual variations of regional water supply pattern, vegetation growth, drought events, and its associated influence ecosystems and human society. We suggest the satellite monitoring system development to quantify meteorological, eco-hydrological, and socio-ecological factors related to drought events, and characterize spatial and temporal drought patterns in Korea. The combination of these complementary remote sensing observations(visible to microwave bands) provide an effective means for evaluating regional variations in the timing, frequency, and duration of drought, and availability of water supply influencing vegetation and crop growth. This integrated drought monitoring could help national capacity to deal with natural disasters.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.2
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• pp.155-163
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• 2014

At gas stations, liquid fuels expand and contract in volume owing to temperature variations. In Korea, the ambient temperature varies between $-15^{\circ}C$ in winter and $35^{\circ}C$ in summer. The volume expansion coefficients of liquid fuels are about $0.1%/^{\circ}C$. To investigate this issue, we measured daily changes in fuel temperature and the delivered fuel temperature at gas stations. In addition, we scrutinized the daily, monthly, and annual changes in temperature over past 50 years in Korea. The results show that the temperature of the fuel in the storage tank was maintained at a stable value(summer or winter). Many factors, such as the surrounding conditions, fuel filling frequency, and gas station location, influence the delivered fuel temperature. The results of this study can be applied for establishing a national regulation and will contribute to fair transactions.

• Journal of Ecology and Environment
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• v.38 no.3
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• pp.281-291
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• 2015

To clarify the effects of forest fire on the carbon budget of a forest ecosystem, this study compared the seasonal variation of soil respiration, net primary production and net ecosystem production (NEP) over the year in unburned and burned Pinus densiflora forest areas. The annual net carbon storage (i.e., NPP) was $5.75t\;C\;ha^{-1}$ in the unburned site and $2.14t\;C\;ha^{-1}$ in the burned site in 2012. The temperature sensitivity of soil respiration (i.e., $Q_{10}$ value) was higher in the unburned site than in the burned site. The annual soil respiration rate was estimated by the exponential regression equation with the soil temperatures continuously measured at the soil depth of 10 cm. The estimated annual soil respiration and heterotrophic respiration (HR) rates were 8.66 and $4.50t\;C\;ha^{-1}yr^{-1}$ in the unburned site and 4.08 and $2.12t\;C\;ha^{-1}yr^{-1}$ in the burned site, respectively. The estimated annual NEP in the unburned and burned forest areas was found to be 1.25 and $0.02t\;C\;ha^{-1}yr^{-1}$, respectively. Our results indicate that the differences of carbon budget and cycling between both study sites are considerably correlated with the losses of living plant biomass, insufficient nutrients and low organic materials in the forest soil due to severe damages caused by the forest fire. The burned Pinus densiflora forest area requires at least 50 years to attain the natural conditions of the forest ecosystem prior to the forest fire.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.197-207
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• 2018

SMEs manufacturing Factory, which are small-scale production systems of various types, mass-produce and sell products in order to meet customer needs. This means that the company has an excessive amount of material supply to reduce the loss due to lack of inventory and high inventory maintenance cost. And the products that fail to respond to the demand are piled up in the management warehouse, which is the reality that the storage cost is incurred. To overcome this problem, this paper uses ARIMA model, a time series analysis technique, to predict demand in terms of seasonal factors. In this way, demand forecasting model based on economic order quantity model was developed to prevent stock shortage risk. Simulation is carried out to evaluate the effectiveness of the development model and to demonstrate the effectiveness of the development model as applied to SMEs in the future.

• The Korean Journal of Quaternary Research
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• v.14 no.2
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• pp.101-107
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• 2000

Using the phytogram system, this study monitored hourly environmental factors(climate and soil), and radial growths and cambium activities of conifers in Worak mountain for 28 months from May 1996 to October 1998 to examine the influences of climatic factors on tree growths/carnbium activities of conifers in Worak Mountain, Korea. The phytogram system first puts a fine electrode into cambial zone. This device can automatically record environmental factors and cambium electrochemistry(hydration and proton levels). Dendrometers are attached to the phytogram for monitoring seasonal dynamics of cambial growth. We compared the results of radial growth by species and by diameter class. The growth decreased in order of Larix leptolepis, Pinus densiflora and Pinus rigida. Pre-monsoon growths were fast and May-June moisture regime was the most critical for all species. In the middle of September, radial growths were finished. The proton level and stem diameter reached the minimum at 4 p.m. On the other hand, the hydration level reached the maximum at 4 p.m. This diurnal change resulted from transpiration and the release of water from phloem storage to sapwood through xylem stream.

• Environmental Engineering Research
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• v.19 no.3
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• pp.261-268
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• 2014

Leachate quality and methane emission from pilot-scale lysimeters operated under semi-aerobic and anaerobic conditions were monitored for 650 days. Two semi-aerobic lysimeters were filled with un-compacted and compacted municipal solid wastes whereas two anaerobic lysimeters containing compacted wastes were operated with leachate storage at 50% and 100% of waste height, respectively. Despite having high moisture in wastes and operating under tropical rainfall events, leachate stabilization in semi-aerobic lysimeters took place much faster resulting in BOD reduction by 90% within 60 days, significantly shorter than 180-210 days observed in anaerobic lysimeters. Nitrogen concentration in leachate from semi-aerobic lysimeter could be reduced by 90%. In term of gas emission, semi-aerobic lysimeter with un-compacted wastes had much lower methane emission rate of $2.8g/m^2/day$ compare to anaerobic lysimeters ($62.6g/m^2/day$) through seasonal fluctuation was observed. Nevertheless, semi-aerobic lysimeter with waste compaction has similar performance to anaerobic lysimeter.