• Journal of the Korea Society of Computer and Information
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• v.15 no.9
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• pp.165-172
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• 2010

Communication problems have been regarded as one of the biggest causes in trouble in many industries. This led to extensive research on communication as a part of human error analysis. The results of existing researches have revealed that maintaining a good quality of communication is essential to secure the safety of a large and complex process system. In this paper, we suggested a method to measure the quality of communication during off-normal situation in main control room of nuclear power plants. It evaluates the cosine similarity that is a measure of sentence similarity between two operators by finding the cosine of the angle between them. To check the applicability of the method to evaluate communication quality, we compared the result of communication quality analysis with the result of operation performance that was performed by operators under simulated environment.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.2
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• pp.136-146
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• 2019

A solid oxide fuel cell (SOFC) based hybrid desiccant cooling system model is developed to study the effect of fuel utilization rate of the SOFC on the reduction of energy consumption and $CO_2$ emission. The SOFC-based hybrid desiccant cooling system consists of an SOFC system and a Hybrid desiccant cooling system (HDCS). The SOFC system includes a stack and balance of plant (BOP), and HDCS. The HDCS consists of desiccant rotor, indirect evaporative cooler, electric heat pump (EHP), and heat exchangers. In this study, using energy load data of a commercial office building and SOFC-based HDCS model, the amount of ton of oil equivalent (TOE) and ton of $CO_2$ ($tCO_2$) are calculated and compared with the TOE and $tCO_2$ generation of the EHP using grid electricity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.53-61
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• 2021

This paper is a preliminary study for the development of a drone for inspection inside a boiler in a thermal power plant, which is a high-temperature environment, and validated whether the drone can fly normally through a high-temperature environment simulation using AirSim. In a high-temperature flight environment, the aerodynamic characteristics of the air density and viscosity are different from room temperature, and the flight performance of the drone is also changed accordingly. Therefore, in order to confirm the change of the aerodynamic characteristics of the propeller according to the temperature change, the propeller analysis and thrust test through JBLADE, and the operation characteristics prediction through the electric propulsion system performance prediction model were performed. In addition, the analysis and performance prediction results were applied to AirSim for simulation, and the aircraft redesigned through the analysis of the results. As a result of the redesign, it was confirmed that about 65% of the maximum power used before the redesign was reduced to 52% to obtain the necessary thrust when hovering in an environment of 80℃.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1676-1685
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• 2021

We develop a new high-fidelity multiphysics model to simulate boron chemistry in the porous Chalk River Unidentified Deposit (CRUD) deposits. Heat transfer, capillary flow, solute transport, and chemical reactions are fully coupled. The evaporation of coolant in the deposits is included in governing equations modified by the volume-averaged assumption of wick boiling. The axial offset anomaly (AOA) of the Seabrook nuclear power plant is simulated. The new model reasonably predicts the distributions of temperature, pressure, velocity, volumetric boiling heat density, and chemical concentrations. In the thicker CRUD regions, 60% of the total heat is removed by evaporative heat transfer, causing boron species accumulation. The new model successfully shows the quantitative effect of coolant evaporation on the local distributions of boron. The total amount of boron in the CRUD layer increases by a factor of 1.21 when an evaporation-driven increase of soluble and precipitated boron concentrations is reflected. In addition, the concentrations of B(OH)₃ and LiBO₂ are estimated according to various conditions such as different CRUD thickness and porosity. At the end of the cycle in the AOA case, the total mass of boron incorporated in CRUD deposits of a reference single fuel rod is estimated to be about 0.5 mg.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.150-152
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• 2019

In this study, the effects of the wave field changes due to the coastal structure on the hydrodynamic performance of the OWC wave energy, converter are analyzed using a three-dimensional numerical wave tank technique (NWT). The OWC device is simulated numerically by introducing a linear pressure drop model, considering the coupling effect between the turbine and the OWC chamber in the time domain. The flow distribution around the chamber is different due to the change of reflection characteristics depending on the consideration of the breakwater model. The wave energy captured from the breakwater is spatially distributed on the plane of the front of the breakwater, and the converted pneumatic power increased when concentrated in front of the chamber. The change of the standing wave distribution is repeated according to the relationship between the incident wavelength and the length of the breakwater, and the difference in energy conversion performance of the OWC was confirmed.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.297-303
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• 2007

Orimulsion, a bitumen-in-water emulsified fuel, has been used throughout the world as a substitute fuel for heavy oil and coal. Orimulsion has relatively high levels of sulfur, nickel, and vanadium, compared to other fuel oils and coals, and has been the subject of much debate regarding the environmental impacts. In Korea, Y power plant has operated boilers with Orimulsion as a fuel, and they has some drawbacks during the plant operation, such as plume opacity. In this study, we investigated the cause of formation mechanism and factors for the plume opacity by investigating the operation data, and measuring the particle size distribution at EP(Electrostatic Precipitator), FGD(Fuel Gas Desulfurization) and TMS(Telecommunications Management System) units. Resulting data showed the primary particles below 1 ${\mu}m$ formed were regrown by the recombination of $SO_3$ in wet-limestone FGD process, and thus the secondary particles are induced to cause the plume opacity.

• Korean Journal of Plant Resources
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• v.29 no.5
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• pp.539-546
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• 2016

The aim of this study was to analyze antioxidant activity, total phenolics, and vitamin C content in unripe and ripe jujube cultivar and to investigate correlation between antioxidant and chemical constituents including total phenolics and vitamin C. The antioxidant activity was measured by the DPPH radical scavenging activity, ABTS radical scavenging activity, and reducing power. Although, the weight, diameter and soluble solids of Zyziphus jujuba fruit were increased with the progress of ripening, antioxidant activity and total phenolics were decrease during ripening. The highest free-radical scavenging activity (at 2.5 ㎎/㎖) and reducing power (at 1 ㎎/㎖) in fruit were 81.75% (Bokjo, unripe) and 0.80 (Mudeung, unripe), respectively. The highest total phenolic content in unripe fruit of Mudeung was 62.50 ㎍/g. A linear correlation (r=0.911) was shown between DPPH radical scavenging activity and total phenolic content.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.48-53
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• 2017

One of the policies of the Ministry of Agriculture, Forestry and Livestock Food and Livestock aims to export $10 billion worth of products. Although it was not easy to achieve the export goal of $ 6.5 billion in 2016, the policy should be pursued continuously. Accordingly, a facility modernization project and high-tech greenhouse project are being implemented to facilitate exports. Moreover, it is possible to consider substitution of imports in the policy shift. Imports of temperate and tropical fresh fruits totaled 1.2 trillion won in 2016. Accordingly, identification of alternatives to tropical and temperate fresh fruit imports will enable farm income to increase and the fresh fruit industry to grow. The major obstacle to tropical fruit production in Korea is high heating costs. However, Jeju Island apple mango farmers found that using non-taxable kerosene and hot water from power plants could reduce heating costs by 42.5%. Indeed, using hot wastewater can reduce heating costs by more than 40%. To improve competition with imported fruits, farmers can change their heating systems using financial support plans (e.g., 20% government subsidies, 20% loans, 30% subsidies from local governments). The income effect and import substitution effect of fruit tree farmers should be carefully analyzed in the future and the study will be closed to discuss the policy direction.

• Journal of Environmental Health Sciences
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• v.44 no.1
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• pp.63-75
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• 2018

Objectives: The aim of this research is to explore the total heavy metals from a coal-fired power plant burning bituminous coal with wood pellets due to the implementation of the Renewable Portfolio Standard policy (RPS, 10% of electricity from renewable energy resources by 2023). Methods: The research was carried out by collecting archival data and using the USEPA's AP-42 & EMEP/EEA compilation of emission factors for use in calculating emissions. The Monte Carlo method was also applied for carrying out the calculations of measurement uncertainty. Results: In this paper, the results are listed as follows. Sb was measured at 110 kg (2015) and calculated as 165 kg (2019) and 201 kg (2023). Cr was measured at 1,597 kg (2015) and calculated as 1,687 kg (2019) and 1,728 kg (2023). Cu was measured at 2,888 kg (2015) and calculated as 3,133 kg (2019) and 3,264 kg (2023). Pb was measured at 2,580 kg (2015) and calculated as 2,831 kg (2019) and 2,969 kg (2023). Mn was measured at 3,011 kg (2015) and calculated as 15,034 kg (2019) and 23,014 kg (2023). Hg was measured at 510 kg (2015) and calculated as 513 kg (2019) and 537 kg (2023). Ni was measured at 1,720 kg (2015) and calculated as 1,895 kg (2019) and 1,991 kg (2023). Zn was measured at 7,054 kg (2015) and calculated as 9,938 kg (2019) and 11,778 kg (2023). Se was measured at 7,988 kg (2015) and calculated as 7,663 kg (2019) and 7,351 kg (2023). Conclusion: This shows that most heavy metals would increase steadily from 2015 to 2023. However, Se would decrease by 7.9%. This analysis was conducted with EMEP/EEA's emission factors due to the limited emission factors in South Korea. Co-firewood pellets in coal-fired power plants cause the emission of heavy metals. For this reason, emission factors at air pollution control facilities would be presented and the replacement of wood pellets would be needed.

• Korean Journal of Plant Resources
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• v.20 no.5
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• pp.461-465
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• 2007

In this study, changes in the overall antioxidant properties and chemical constituents including total phenolics and vitamin C of R. occidentalis fruit during ripening are studied. The antioxidant activity was measured by the free-radical scavenging activity(DPPH method) and reducing power(potassium ferricyanide method). Although, the weight and diameter of R. occidentalis fruit were increased with the progress of ripening, antioxidant activity and total phenolics were decrease during ripening. The highest free-radical scavenging activity(at $125{\mu}g/m{\ell}$) and reducing power(at $100{\mu}g/m{\ell}$) in fruit were 61.67% and 0.71, respectively. Total phenolic content and vitamin C content in fruit of 5 days after fruit set were $220.73{\mu}g/g$ and $540.45{\mu}g/g$, respectively. A linear correlation(r=0.9761) was shown between free-radical scavenging activity and total phenolic content.