• Journal of Power System Engineering
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• v.19 no.4
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• pp.50-55
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• 2015

Recently, because of the deterioration of the nuclear generating station and increase of the cooler and heater, energy problem is increasing. To save the energy, the free cooling system is developed. The free cooling system is that cool the water to use cooled air in winter and is used in industrial process or data center. Yoon check the energy of free cooling system with dry cooler in korea. In this study, the value of the free cooling system with dry cooler is confirmed through using the NPV that is economic evaluation. when temperature degree of the cooled water is 10, in Chuncheon and Seoul the value is the most high. When temperature degree of the cooled water is 20, in Ulsan the value is the most high. As the result, because the using the temperature degree of the cooled water is high in the industrial process, the free cooling system is advantageous in korea.

• Nuclear Engineering and Technology
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• v.42 no.5
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• pp.562-567
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• 2010

A One-Dimensional Water Flow and Contaminant Transport in Unsaturated Zone (FTUNS) code has been developed in order to interpret radionuclide migration in an unsaturated zone. The pore-size distribution index (n) and the inverse of the air-entry value ($\alpha$) for an unsaturated zone were measured by KS M ISO 11275 method. The hydraulic parameters of the unsaturated soil are investigated by using soil from around a nuclear facility in Korea. The effect of hydraulic parameters on radionuclide migration in an unsaturated zone has been analyzed. The higher the value of the n-factor, the more the cobalt concentration was condensed. The larger the value of $\alpha$-factor, the faster the migration of cobalt was and the more aggregative the cobalt concentration was. Also, it was found that an effect on contaminant migration due to the pore-size distribution index (n) and the inverse of the air-entry value ($\alpha$) was minute. Meanwhile, migrations of cobalt and cesium are in inverse proportion to the Freundich isotherm coefficient. That is to say, the migration velocity of cobalt was about 8.35 times that of cesium. It was conclusively demonstrated that the Freundich isotherm coefficient was the most important factor for contaminant migration.

• KIEAE Journal
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• v.7 no.6
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• pp.23-28
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• 2007

Limited fossil fuels and unstable energy supply are considered as one of the critical problems in architecture requiring large amounts of energy. In order to this challenge, environment-friendly architecture design is required. Clear data should be prepared to apply solar energy to architecture aggressively and properly. This study used FS statistical analysis data regarding average daily solar radiation of Seoul observed over 20 years to find out standard year and standard daily solar radiation. This study also aims to compare and evaluate an appropriate method of selecting a standard year which is too close to measurement value through comparison and analysis with daily solar radiation acquired by applying overseas researchers' suggesting weight factor. As a result, the data nearest to measurement value of daily solar radiation was UK CIBSE TRY(TYPE 2) displaying 0.100in t-statistic index. For UK CIBSE TRY(TYPE 2), weight factor was applied to three climatic elements except relative humidity. TYPE 1 and TYPE 3 recorded 0.343 and 0.367, respectively, showing higher record of t-statistic than TYPE 2. TYPE 1 was calculated through FS statistical value of single data about daily solar radiation with other climatic elements excluded. For TYPE 3, relative humidity was added to TYPE 2. In particular, since TYPE 2 was closer to the measurement value compared to the others, it is necessary to consider relationship with other climate elements if other climate elements are added.

• ETRI Journal
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• v.43 no.4
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• pp.674-683
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• 2021

A trust-aware secure routing protocol (TSRP) for wireless sensor networks is proposed in this paper to defend against varieties of attacks. First, each node calculates the comprehensive trust values of its neighbors based on direct trust value, indirect trust value, volatilization factor, and residual energy to defend against black hole, selective forwarding, wormhole, hello flood, and sinkhole attacks. Second, any source node that needs to send data forwards a routing request packet to its neighbors in multi-path mode, and this continues until the sink at the end is reached. Finally, the sink finds the optimal path based on the path's comprehensive trust values, transmission distance, and hop count by analyzing the received packets. Simulation results show that TSRP has lower network latency, smaller packet loss rate, and lower average network energy consumption than ad hoc on-demand distance vector routing and trust based secure routing protocol.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2570-2575
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• 2024

The study aims to develop a novel, lead-free, flexible and lightweight composite shielding material against ionizing radiation. For this, it was used bismuth oxide (Bi₂O₃) in RTV-2 silicon matrix. The shielding tests were carried out in both diagnostic X-ray energies and intermediate gamma-ray energy range of up to 662 keV to determine the radiation attenuation properties of this material in terms of attenuation ratio, half value layer, tenth value layer, mean free path and lead equivalency of samples in weight of 30%, 40%, 50% in Bi₂O₃. In the diagnostic X-ray energy range, half value layer, tenth value layer and lead equivalency (in mm Pb) of the produced samples were measured at 80 and 100 kVp narrow beam conditions according to the requirements of EN IEC 61331-1 standard. The results show that lead equivalent values of the produced novel sheets was measured to be 0.16 mm Pb, corresponding to a 6 mm thickness of the flexible sample when it contains 30% wt. Bi₂O₃ in RTV matrix. The experimental findings for durability and flexibility also indicated that this new RTV-based flexible, lead -free shielding composite can be used safely for especially for manufacturing aprons, garments and thyroid guards used in mammography, radiology, nuclear medicine and dental applications in practice.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.13 no.3
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• pp.9-15
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• 2017

In this study, set values of PICV(Pressure Independent Control Valve) were simulated according to the pressure distribution and velocity. The higher the set value and the open rate, as the lower the pressure in the neck. On the contrary, the lower the set value and open rate, as the higher the pressure in the neck. When the set value was small, the pressure was distributed sufficiently and confirmed that the pressure was generated by the VOF, confirming that it could generate a vapor pressure. When the set value 100 %, the lower corn open rate of the differential pressure was 46 % to 29 %, set value 100 % was 29 % to 19 %, and set value 6 % was 12 % to 6 % for the lower corn open rate percentile, it was limited to within 50 %. Thus, the results of this study on the correlation between open rate and differential pressure of the set value of the PICV will be beneficial to improve performance of flow control valves and contribute to their efficient operation used for a hydronic system.

• Advances in concrete construction
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• v.14 no.3
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• pp.215-225
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• 2022

Thermal comfort and energy conservation are critical issues in the building sector. Energy consumption in the building sector should be reduced whilst enhancing the thermal comfort of occupants. Concrete is the most widely used construction material in buildings. Its thermal conductivity (k-value) has a direct effect on thermal comfort perception. This study aims to find the optimum value of replacing the normal aggregate with lightweight expanded clay aggregate (LECA) under high strengths and low thermal conductivity, density and water absorption. The k-value of the LECA concrete and its physical and mechanical properties have varying correlations. Results indicate that the oven-dry density, compressive strength, splitting tensile strength and k-value of concrete decrease when normal coarse aggregates are replaced with LECA. However, water absorption (initial and final) increases. Thermal conductivity and the physical and mechanical properties have a strong correlation. The statistical optimisation of the experimental data shows that the 39% replacement of normal coarse aggregate by LECA is the optimum value for maximising the compressive and splitting tensile strengths whilst maintaining the k-value, density and water absorption at a minimum.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.385-386
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• 2023

In this application study, field pilot tests were performed to evaluate the validity of a proposed formula between the exerted electrical energy and SPT N-value based on the result of the basic study. Measurement sensors and recording system were developed to obtain exerted motor current and drilling depth in a field. By using the correlation formula proposed in the basic study, the measured motor current and boring speed were applied to predict SPT N-value and the predicted N-values were compared to SPT N-value of site exploration. From the comparisons it is verified that the exerted electrical energy to bore ground might be used to predict SPT N-value and pile tip location.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.4
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• pp.5-13
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• 2017

With the purpose of energy recovery from sludge having calorific value as fuel we investigated the current status and characteristics of sludge in Korea in order to understand the type and amount of sludge that can recover energy. 'The Status Report on Waste Generation and Treatment in Korea' announced that 152 million tons of wastes were generated nationwide in 2015 and 9.2 % of the whole waste disposed into landfills which includes 15.1 % of the total industrial wastes. The average of upper calorific values of sewage sludge was 3,021 kcal/kg and that of wastewater sludge was 2,472 kcal/kg respectively. In order to determine the sludge as fuel, each correlations between calorific value, carbon content and combustibility ratio were evaluated. In the study, the current status and characteristics of sludge in Korea were investigated in order to understand the type and amount of sludge as fuel to recover energy. It is predicted that if the energy of sludge having a calorific value of 6 MJ/kg($${\sim_=}1,500kcal/kg$$) or more is recovered as fuel, the amount of the sludge disposed into landfills can be reduced about 40 %.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.5
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• pp.680-683
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• 2001

The apparent metabolisable energy (AME) and N-corrected ME (AMEn) of deoiled rice bran (DORB) were determined with adult quails at 6 and 10- week of age. The DORB obtained from two types of extraction process, Batch (DORB-B) and the Continuous (DORB-C), was each included in a practical type of the reference diet at 20 or 40% level. The analysed crude protein, ether extract, total ash, calcium, phosphorus, glucose and starch content of DORB-B and DORB-C were found at 19.0, 0.79, 17.05, 0.11, 1.92, 2.3, 11.22, and 15.02, 1.56, 13.0, 0.40, 2.76, 2.16, 19.0, respectively. The level of inclusion of DORB in diet appeared to exert a significant effect on the AME and AMEn values. When bioassayed at 20% inclusion level the DORB was found to have a significantly (p<0.01) lower value than that obtained at 40% inclusion level. However, no significant effect of age of quails on the AME values of DORB was evident. The ME bioassays with quails gave significantly (p<0.01) higher AME values for DORB-C than DORB-B thereby indicating that the continuous system of solvent extraction of rice bran is superior to the batch system from this point of view. The AME value of DORB predicted from its chemical composition also revealed that the DORB-C contained approximately 15% more energy than that in DORB-B.