• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.199-207
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• 2014

In this paper, to systematically assess the abandonment risk of main control room (MCR) fire, fire simulations with Fire Dynamics Simulator were performed and abandonment probabilities were estimated for the MCR bench-board fire of domestic reference nuclear power plant. The fire simulation scenarios performed in this study included propagating and non-propagating fires of the MCR bench-board, and the availability and unavailability of heating, ventilation, and air conditioning system (HVACS). The following results were obtained. First, temperature was the major abandonment impact factor for the MCR bench-board fire if the HVACS was available and optical density was that if the HVACS was unavailable. Second, the fire scenario contributing the MCR bench-board fire abandonment risk was identified to be only the propagating fire. Third, it was confirmed that the abandonment probability of the MCR bench-board fire for domestic reference nuclear power plant could be reduced by using the fire modeling.

• Journal of the Korean Society of Combustion
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• v.18 no.3
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• pp.44-53
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• 2013

In this study, the economic evaluation for imported coals was conducted for power plant based on thermo-dynamical performance analysis. The number of coal types considered was 1,755 imported by five power generation companies in Korea during the 2010-2012. The higher heating value (HHV) of the coals ranged 4,000-6,500 kcal/kg, mostly sub-bituminous. The 1D thermo-dynamical performance modeling was performed for a 500 MWe standard power plant using PROATES code. It was founded that the low rank coals had negative effects on the plant efficiency mainly due to the increased heat loss by moisture, hydrogen and flue gas. Based on the performance analysis, the economic performance of the coals was evaluated. The apparent price of low-rank coals tended to be significantly lower than design coal; for example, the unit price of coal with a HHV of 4,000 kcal/kg was 57% of the reference coal having 6,080 kcal/kg. Considering the negative effects leading to a decrease in the thermal performance, heating value compensation, and increased parasite load, the corrected unit cost for the coal with 4,000 kcal/kg was 90.7% of the reference coal. Overall, the cost saving by imported coals was not high as expected.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.2
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• pp.81-88
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• 2018

Performance evaluation of a plant to efficiently manage and maintain the performance of the plant is a very important procedure. However, since the conventional performance evaluation method is an Excel-based manual method, the preparation procedure is complicated and the versatility is poor. In this paper, we analyze the problems of the existing performance evaluation system, effectively model the equipment, calculate the missing physical properties, and improve the versatility, efficiency and accuracy of the performance evaluation through the equipment modeler which performs automatic index calculation based on this.

• Journal of Environmental Health Sciences
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• v.49 no.4
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• pp.201-209
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• 2023

Background: To describe domain knowledge consistently and precisely, the establishment of a controlled vocabulary, a so-called ontology, is essential. Internationally, the plant ontology (PO) in the ecology field has been developed for the anatomy and developmental stages of plants in English, Spanish, and Japanese, but there is no Korean version of the PO due to a lack of knowledge on standardization for Korean plants. Objectives: We aimed to establish a Korean plant ontology with core PO architectures. Methods: The latest ontology web language (OWL)-formatted raw version of the PO was collected from the PO consortium site. A formal workflow process and OWL file-handing tools for efficient Korean content development were conducted and executed. Results: The macro- and micro-perspective frameworks of the PO were presented by analyzing the upper model and the internal OWL-leveled physical structure, respectively. We developed and validated Korean knowledge content for a total of 1,957 classes included in the PO and transplanted them into an ontology modeling system. Conclusions: A Korean plant ontology was established for international harmonization through improved compatibility and data exchangeability with multilingual environmental and ecological knowledge bases.

• Journal of Korea Water Resources Association
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• v.53 no.7
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• pp.545-555
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• 2020

A feasibility modeling for potential hydroelectric dam site selection was suggested using 1 sec ASTGTM (ASTER Global Digital Elevation Model) and Terra/Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) derived land use (MCD12Q1) data. The modeling includes DEM pre-processing of peak, sink, and flat, river network generation, watershed delineation and segmentation, terrain analysis of stream cross section and reservoir storage, and estimation of submerged area for compensation. The modeling algorithms were developed using Python and as an open source GIS. When a user-defined stream point is selected, the model evaluates potential hydroelectric head, reservoir surface area and storage capacity curve, watershed time of concentration from DEM, and compensation area from land use data. The model was tested for 4 locations of already constructed Buhang, BohyunMountain, Sungdeok, and Yeongju dams. The modeling results obtained maximum possible heads of 37.0, 67.0, 73.0, 42.0 m, surface areas of 1.81, 2.4, 2.8, 8.8 ㎢, storages of 35.9, 68.0, 91.3, 168.3×10⁶ ㎥ respectively. BohyunMountain and Sungdeok show validity but in case of Buhang and Yeongju dams have maximum head errors. These errors came from the stream generation error due to ASTGTM. So, wrong dam watershed boundary limit the head. This study showed a possibility to estimate potential hydroelectric dam sites before field investigation especially for overseas project.

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

• Journal of Ecology and Environment
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• v.47 no.2
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• pp.49-62
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• 2023

Background: Over the past three decades, gradual eustatic sea-level rise has been considered a primary exogenous factor in the increased frequency of flooding and biological changes in several salt marshes. Under this paradigm, the potential importance of short-term events, such as ocean storminess, in coastal hydrology and ecology is underrepresented in the literature. In this study, a simulation was developed to evaluate the influence of wind waves driven by atmospheric oscillations on sedimentary and vegetation dynamics at the Skallingen salt marsh in southwestern Denmark. The model was built based on long-term data of mean sea level, sediment accretion, and plant species composition collected at the Skallingen salt marsh from 1933-2006. In the model, the submergence frequency (number yr^-1) was estimated as a combined function of wind-driven high water level (HWL) events (> 80 cm Danish Ordnance Datum) affected by the North Atlantic Oscillation (NAO) and changes in surface elevation (cm yr^-1). Vegetation dynamics were represented as transitions between successional stages controlled by flooding effects. Two types of simulations were performed: (1) baseline modeling, which assumed no effect of wind-driven sea-level change, and (2) experimental modeling, which considered both normal tidal activity and wind-driven sea-level change. Results: Experimental modeling successfully represented the patterns of vegetation change observed in the field. It realistically simulated a retarded or retrogressive successional state dominated by early- to mid-successional species, despite a continuous increase in surface elevation at Skallingen. This situation is believed to be caused by an increase in extreme HWL events that cannot occur without meteorological ocean storms. In contrast, baseline modeling showed progressive succession towards the predominance of late-successional species, which was not the then-current state in the marsh. Conclusions: These findings support the hypothesis that variations in the NAO index toward its positive phase have increased storminess and wind tides on the North Sea surface (especially since the 1980s). This led to an increased frequency and duration of submergence and delayed ecological succession. Researchers should therefore employ a multitemporal perspective, recognizing the importance of short-term sea-level changes nested within long-term gradual trends.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.113.1-113.1
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• 2010

IGCC(Integrated Coal Gasification and Combined Cycle) plants can be among the most advanced and environmental systems for electric energy generation from various feed stocks and is becoming more and more popular in new power generation fields. In this work, the performance of IGCC plants employing Shell gasification technology and a GE 7FB gas turbine engine was simulated using IPSEpro open-equation modeling environment for different operating conditions. Performance analyses and comparisons of all operating cases were performed based on the design cases. Discussions were focused on gas composition, syngas production rate and overall performance. The validation of key steady-state performance values calculated from the process models were compared with values from the provided heat and material balances for Shell coal gasification technology. The key values included in the validation included the inlet coal flow rate; the mass flow rate, heating value, and composition of major gas species (CO, H2, CH4, H2O, CO2, H2S, N2, Ar) for the syngas exiting the gasifier island; and the HP and MP steam flows exiting the gasifier island.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.382-388
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• 2017

This study performed an OpenFOAM-based numerical modeling for simulating performance of wave reduction by a floating vertical plate. Based on the Waves2FOAM library, an internal wave generation and energy dissipation with sponge layers schemes were further implemented. The performance of wave generation and dissipation was first tested with a simple two-dimensional analysis. Then, numerical simulation was carried out with the experimental data of Briggs et al. (2001) for the two regular wave cases. In general, the modeling results agreed well with the experimental data, showing better agreement than the numerical analysis by WAMIT that is included in Briggs et al. (2001).

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.541-544
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• 2005

This study presents the integrated modeling approach to simulate the proton exchange membrane (PEM) fuel cell system for vehicle application. The fuel cell system consisting of stack and balance of plant (BOP) was simulated with MATLAB/Simulink environment to estimate the maximum system power and investigate the effect of BOP component sizing on system performance and efficiency. The PEM fuel cell stack model was established by using a semi-empirical modeling. To maximize the net efficiency of fuel cel1 system, multi-variable optimization code was adopted. Using this method the optimized operating values were obtained according to various system net power levels. The fuel cell model established was co-linked to AVL CRUISE, a vehicle simulation package. Through the vehicle simulation software, the fuel economy of fuel cell powered electric vehicle for two types of driving cycles was presented and compared. It is expected that this study tan be effectively employed in the basic BOP component sizing and in establishing system operation map with respect to net power level of fuel cell system.