• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.27-39
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• 2022

The smart farm is recognized as a solution for future farmers having positive effects on the sustainability of the poultry industry. Intelligent microclimate control can be a key technology for broiler production which is extremely vulnerable to abnormal indoor air temperatures. Furthermore, better control of indoor microclimate can be achieved by accurate prediction of indoor air temperature. This study developed predictive models for internal air temperature in a mechanically-ventilated broiler house based on the data measured during three rearing periods, which were different in seasonal climate and ventilation operation. Three machine learning models and a mechanistic model based on thermal energy balance were used for the prediction. The results indicated that the all models gave good predictions for 1-minute future air temperature showing the coefficient of determination greater than 0.99 and the root-mean-square-error smaller than 0.306℃. However, for 1-hour future air temperature, only the mechanistic model showed good accuracy with the coefficient of determination of 0.934 and the root-mean-square-error of 0.841℃. Since the mechanistic model was based on the mathematical descriptions of the heat transfer processes that occurred in the broiler house, it showed better prediction performances compared to the black-box machine learning models. Therefore, it was proven to be useful for intelligent microclimate control which would be developed in future studies.

• Plant Journal
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• v.11 no.2
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• pp.45-51
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• 2015

In this paper, studied condenser operating management which is affecting power plants efficiency considering the cost of poor quality. Sea water temperature and condenser pressure have clear correlation in S power plants. As the sea water temperature changes, condenser pressure changed -1.7~+20 mmHg from design condenser pressure(38.1 mmHg). Use the heat rate correction curve from manufactory company, realized that efficiency and cost of poor quality changed 0.0201%, 12,830 won/h at Unit #1,2 but 0.0155%, 9,832 won/h when condenser pressure 1 mmHg rise. Also, checked that it is changed depend on seasonal corresponding operation, plant ageing and the point of preventive maintenance like overhaul maintenance. This study said if we considered complying with management range and planning overhaul maintenance, then it could help reducing operating maintenance losses minimum 2.5 billion won per 1 year (case : Unit #1, forty days maintenance).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.10
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• pp.729-737
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• 2022

Melting and icing process of the PCMTCU(Phase Change Material Thermal Control Unit) installed on the NEXTSat-2, which is scheduled to be launched in the second half, was investigated through the results of satellite-level TVT(Thermal Vacuum Test). As a result of the test, it was confirmed that the latent heat of PCM contributes to the temperature stabilization of the heating components. The thermal model for numerical analysis of the PCMTCU was correlated to acquire a reasonable degree of accuracy using the collected temperature measurements during TVT. The periodic temperature variation of the PCMTCU in normal on-orbit operation was predicted with the correlated thermal model, and the quantitative contribution of the PCM on the thermal energy management was evaluated with the liquid fraction. It will receive flight telemetry from the NEXTSat-2 after the launch, and complete the space verification of the PCMTCU.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.3
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• pp.353-364
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• 2019

The walk-way means a passage installed on the deck of a ship so that a person can safely move under any circumstances. So, the walk-way has to maintain a temperature of $5^{\circ}C$ or more for anti/de-icing even at an ambient temperature of $-62^{\circ}C$, a temperature in polar region. At present, the walk-way with heating cable is used, but the anti/de-icing effect is insufficient due to low heat transfer efficiency. Also, it has a construction problem due to heavy weight. In this study, an walk-way with a CNT surface heating element is proposed for the high anti/de-icing effect and the heating value per unit volume. The international standard survey, conceptual design, and simulation for the structural safety and the heat transfer are performed for the development of the proposed walk-way. To enhance the performance, the case studies based on the simulation analysis are conducted. Finally, the final prototype, applying the optimum material and thickness (3.2t of SS400) based on the case study results, is fabricated and experimented.

• Nuclear Engineering and Technology
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• v.43 no.4
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• pp.317-328
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• 2011

Pyroprocessing technology was developed in the beginning for metal fuel treatment in the US in the 1960s. The conventional aqueous process, such as PUREX, is not appropriate for treating metal fuel. Pyroprocessing technology has advantages over the aqueous process: less proliferation risk, treatment of spent fuel with relatively high heat and radioactivity, compact equipment, etc. The addition of an oxide reduction process to the pyroprocessing metal fuel treatment enables handling of oxide spent fuel, which draws a potential option for the management of spent fuel from the PWR. In this context, KAERI has been developing pyroprocessing technology to handle the oxide spent fuel since the 1990s. This paper describes the current status of pyroprocessing technology development at KAERI from the head-end process to the waste treatment. A unit process with various scales has been tested to produce the design data associated with the scale up. A performance test of unit processes integration will be conducted at the PRIDE facility, which will be constructed by early 2012. The PRIDE facility incorporates the unit processes all together in a cell with an Ar environment. The purpose of PRIDE is to test the processes for unit process performance, operability by remote equipment, the integrity of the unit processes, process monitoring, Ar environment system operation, and safeguards related activities. The test of PRIDE will be promising for further pyroprocessing technology development.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.489-495
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• 2006

Proton exchange membrane (PEM) should be sufficiently hydrated with a careful consideration of heat and water management. Water management has been a critical operation issue for better understanding the operation and optimizing the performance of a PEM fuel cell. The flooding on cathode side resulting from excess water can limit the fuel cell performance. In this study, the visual cell was designed and fabricated fur the visualization of liquid water droplet dynamics related to cathode flooding in flow channels. The experiment was carried out to observe the formation, growth and removal of water droplets using CCD imaging system. Effects of operating conditions such as cell temperature, air flow rate and air relative humidity on cathode flooding characteristics were mainly investigated. Based on this study, we can get the basic insight into flooding phenomena and its two-phase flow nature. It is expected that data obtained can be effectively used fur the setup and validation of two-phase PEM fuel cell models considering cathode flooding.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.6
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• pp.40-44
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• 2014

In this paper, maximum power is the lowering device using the facility's energy use and peak load electricity through analyzing attitude should like to make it reduce its power base rate. Simulator to manage the demand for power, a maximum electric power base power from electronic watt-hour meters by a device's signal, predictive power, the current power by computing the goal of power for less than Maximum peak power and peak shift, so that you can manage, and peak York, which role you want a cut Metal heat treatment result which analyzes the data, demand for electricity company over the years of analyzing the characteristics of each load, and effects and Reducing power consumption device every month identified seven Sequence control to the load system and successful power control is about showing that the defined goals.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.1100-1107
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• 2024

The nuclear waste attributes of near-term deployable SMRs were assessed using established nuclear waste metrics, which are the DU mass, SNF mass, volume, activity, decay heat, radiotoxicity, and decommissioning LLW volumes. Metrics normalized per unit electricity generation were compared to a reference large PWR. Three SMRs, VOYGR, Natrium, and Xe-100, were selected because they represent a range of reactor and fuel technologies and are active designs deployable by the decade's end. The SMR nuclear waste attributes show both some similarities to the PWR and some significant differences caused by reactor-specific design features. The DU mass is equivalent to or slightly higher than the PWR. Back-end waste attributes for SNF disposition vary, but the differences have a limited impact on long-term repository isolation. SMR designs can vary significantly in SNF volume (and thus heat generation density). However, these differences are amenable to design optimization for handling, storage, transportation, and disposal technologies. Nuclear waste attributes from decommissioning vary depending on design and decommissioning technology choices. Given the analysis results in this study and assuming appropriate waste management system and operational optimization, there appear to be no major challenges to managing SMR nuclear wastes compared to the reference PWR.

• Corrosion Science and Technology
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• v.15 no.6
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• pp.320-325
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• 2016

To perform ultrasonic testing (UT) thickness measurement of the secondary side piping installed in nuclear power plants, the insulation for preventing heat loss should be removed. The type of insulation can be divided into fixed and removable insulation. Fixed and removable insulation have their own strengths and weaknesses. Removable insulation has been installed in the components susceptible to wall thinning caused by FAC and erosion from Shin-Kori unit 1, which commenced its commercial operation in 2011. In this paper, the number of repeated inspections of components and the number of replacements of fixed insulation were estimated and a more economical way was identified based on the manufacturing and installation costs for fixed and removable insulation.

• Journal of Korean Society for Quality Management
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• v.46 no.1
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• pp.169-188
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• 2018

Purpose: The purpose of this study is to analyze low-temperature starting performance of the light attacker and to search and improve the aircraft system including battery and Battery Charge and Control Unit(BCCU). Methods: In order to improve the starting up performance of the light attacker at low-temp, various deficiency cause were derived and analyzed using Fault Tree Analysis method. As a result, it was confirmed there were drawbacks in the charging and discharging mechanism of the battery. The inactivation of the battery's electrolyte at low-temp and the premature termination of the battery charge were the main cause. After long error and trial, we improved these problems by improving performance of battery and optimizing the charging algorithm of BCCU. Results: It was confirmed that the problems of starting up failures were solved through the combined performance test of the battery and BCCU, the ground test using the aircraft system and the operation test conducted by Korea Airforce operating unit for 3 months in winter. Conclusion: This study showed that the improvement of quality reliability was achieved and thus the start-up performance issue of the light attacker has been resolved at low temperature. And it is expected that the design methodologies of temperature-affected electrical system of aircraft will contribute to the development of the aircraft industry in the future.