• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.286-296
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• 2016

Offshore CCS technology is to transport and inject $CO_2$ which is captured from the power plant into the saline aquifer or depleted oil-gas fields. The more accumulated injected $CO_2$, the higher reservoir pressure increases. The increment of reservoir pressure make a dramatic change of the operating conditions of transport and injection systems. Therefore, it is necessary to carefully analyze the effect of operating condition variations over the injection period in early design phase. The objective of this study is to simulate and analyze the $CO_2$ behavior in the transport and injection systems over the injection period. The storage reservoir is assumed to be gas field in the East Sea continental shelf. The whole systems were consisted of subsea pipeline, riser, topside and wellbore. Modeling and numerical analysis were carried out using OLGA 2014.1. During the 10 years injection period, the change of temperature, pressure and phase of $CO_2$ in subsea pipelines, riser, topside and wellbore were carefully analyzed. Finally, some design guidelines about compressor at inlet of subsea pipeline, heat exchanger on topside and wellhead control were proposed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.5
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• pp.453-461
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• 2015

In order to manage the deflection of a curved PCT girder bridge during construction, a GPS receiver was installed at the spot predicted to be the weak point during the incremental launching so as to measure the deflection at each construction stage. The deflections obtained in the experiment were compared with those derived from the monitoring of stress, temperature and inclination. The comparative analysis of the GPS measurement and analytical values obtained from finite element modeling with respect to the launching distance showed that the measured values differ by 0.6 to 1.6 times to the analytical results. This difference could be significantly reduced by thermal calibration. From the analysis of the behavioral pattern of the bridge, deflection occurred during construction in the concrete tip due to the deflection at the head of the nose at the 95m and 75m-spots, and compression and tension developed respectively at the compression weak zone and tension weak zone. The application of GPS appeared to enable more efficient management of the deflection during the erection of the curved PCT girder bridge and is expected to be helpful for the prediction and management of the behavior in future ILM construction sites.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.4
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• pp.321-332
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• 2017

In order to build a general model of a high-throughput uranium electrorefining process according to the electrode configuration, numerical analysis was conducted using the COMSOL Multiphysics V5.3 electrodeposition module with Ordinary Differential Equation (ODE) interfaces. The generated model was validated by comparing a current density-potential curve according to the distance between the anode and cathode and the electrode array, using a lab-scale (1kg U/day) multi-electrode electrorefiner made by the Korea Atomic Energy Research Institute (KAERI). The operating temperature was $500^{\circ}C$ and LiCl-KCl eutectic with 3.5wt% $UCl_3$ was used for molten salt. The efficiency of the uranium electrorefining apparatus was improved by lowering the cell potential as the distance between the electrodes decreased and the anode/cathode area ratio increased. This approach will be useful for constructing database for safety design of high throughput spent nuclear fuel electrorefiners.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.286-292
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• 2005

This study is to investigate the industrial boiler which can be significantly affected by the restriction of NOx. Note that the application of SNCR method to industrial boiler is usually blown as not feasible due to the insufficient residence time for proper mixing. The purpose of this study is to investigate the applicability of the SNCR system application to the industrial boiler, which produces 40 tons of steam per hour using heavy oil. For the industrial boiler with 3-D rectangular coordinate, the general coding are made fur various turbulence modeling such as turbulent flow, turbulent fuel combustion, thermal NO formation and destruction together with the NO reaction with reducing agents. Further, the incorporation of drop trajectory model is successfully made in 3-D rectangular coordinate with Lagrangian frame and the main swirl burner effect on the characteristics of flame is considered. As expected a short flame was created and thereby NOx is removed more efficiently by increasing the proper region of temperature for NO reduction reaction. The validation of program was made successfully by the comparison of experimental data. Based on the reliable calculation results, the SNCR method in a industrial boiler shows the possibility as one of viable NO reduction method by the use of well designed mixing air of reducing agent.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.536-539
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• 2018

In this paper, we propose a system that analyzes environment information by using deep learning and then provides a suitable environment for users by predicting environmental information change. As the level of living improves, interest in improving the quality of life is increasing. In particular, as the air quality deteriorated due to the recent occurrence of dust, smog, fine dust, and ultrafine dust, the indoor air quality as well as the outdoor air became a serious problem. The increase of indoor pollution due to the lack of ventilation and the use of chemicals is a serious problem for modern people who have a lot of indoor living. In order to solve this indoor air pollution, a system has been proposed that measures the state of air quality through sensors and maintains proper temperature and humidity. However, existing system has a difficulty to apply most of the atmospheric environment information to various users depending on sensors only. The system proposed in this paper predicts the indoor environment by analyzing the indoor pollution information collected through the sensor using the deep learning. Then, the predicted indoor environment is modeled and learned in this system, and the environment suitable for the user is suggested. Afterwards, the system receives feedback from the user and repeats the process of re-learning the proposed environment so that it can create the optimal environment for the user.

• Journal of Korea Water Resources Association
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• v.47 no.8
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• pp.671-684
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• 2014

Change point analysis is a efficient tool to understand the fundamental information in hydro-meteorological data such as rainfall, discharge, temperature etc. Especially, this fundamental information to change points to future rainfall data identified by reasonable detection skills can affect the prediction of flood and drought occurrence because well detected change points provide a key to resolve the non-stationary or inhomogeneous problem by climate change. Therefore, in this study, the comparative study to assess the performance of the 3 change point detection skills, cumulative sum (CUSUM) method, Bayesian change point (BCP) method, and segmentation by dynamic programming (DP) was performed. After assessment of the performance of the proposed detection skills using the 3 types of the synthetic series, the 2 reasonable detection skills were applied to the observed and future rainfall data at the 5 rainfall gauges in South Korea. Finally, it was suggested that BCP (with 0.9 posterior probability) could be best detection skill and DP could be reasonably recommended through the comparative study. Also it was suggested that BCP (with 0.9 posterior probability) and DP detection skills to find some change points could be reasonable at the North-eastern part in South Korea. In future, the results in this study can be efficiently used to resolve the non-stationary problems in hydrological modeling considering inhomogeneity or nonstationarity.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.61-67
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• 2015

The cooling of hot exhaust gas is an important issue for the construction of combustor test facility. Water spray is an effective method for exhaust gas cooling due to its large latent heat in process of evaporation. In this study, 1-D analysis has been performed based on continuity, energy conservation, and saturated vapor property to understand water spray cooling of combustion gas. In the exhaust duct of combustor test facility, the injected water decreases combustion gas temperature, and evaporates in the combustion gas. However, some of the injected water is collected in the sump due to condensation. The evaporation of water helps combustion gas cooling, but causes pressure increase inside the exhaust duct due to increase of vapor pressure. These phenomena has been analyzed by 1-D modeling in this study. From 1-D analysis, the adequate mass flow rate of water spray to cool combustion gas and to avoid excessive pressure rise inside the exhaust duct has been decided.

• Journal of the Korean Ceramic Society
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• v.56 no.2
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• pp.111-129
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• 2019

Recently, all-solid-state batteries (ASSBs) have attracted increasing interest owing to their higher energy density and safety. As the core material of ASSBs, the characteristics of the solid electrolyte largely determine the performance of the battery. Thus far, a variety of inorganic solid electrolytes have been studied, including the NASICON-type, LISICON-type, perovskite-type, garnet-type, glassy solid electrolyte, and so on. The garnet Li₇La₃Zr₂O₁₂ (LLZO) solid electrolyte is one of the most promising candidates because of its excellent comprehensively electrochemical performance. Both, experiments and theoretical calculations, show that cubic LLZO has high room-temperature ionic conductivity and good chemical stability while contacting with the lithium anode and most of the cathode materials. In this paper, the crystal structure, Li-ion transport mechanism, preparation method, and element doping of LLZO are introduced in detail based on the research progress in recent years. Then, the development prospects and challenges of LLZO as applied to ASSBs are discussed.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.240-245
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• 2016

This study was conducted to predict the changes of potential distribution for invasive alien plant, Amaranthus viridis in Korea. The habitats of A. viridis were roadside, bare ground, farm area, and pasture, where the interference by human was severe. We used maximum entropy modeling (MaxEnt) for analyzing the environmental influences on A. viridis distribution and projecting on two different representative concentration pathways (RCP) scenarios, RCP 4.5 and RCP 8.5. The results of our study indicated annual mean temperature, elevation and precipitation of coldest month had higher contribution for A. viridis potential distribution. Projected potential distribution of A. viridis will be increased by 110% on RCP 4.5, 470% on RCP 8.5.

• Ecology and Resilient Infrastructure
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• v.5 no.3
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• pp.189-198
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• 2018

In 21th century, climate change is one of the fundamental issue. Greenhouses gases are pointed as the main cause of climate change. Soil play a vital role of carbon sink and also can be a huge source of greenhouse gases defense on the management. Flux of greenhouse gases is not the only factor can be changed by climate change. Climate change can alter proper management. Temperature change will modify crop planting and harvesting date. Other management skills like fertilizer, manure, irrigation, tillage can also be changed with climate change. In this study, greenhouse gases emission in rice paddy in South Korea is simulated with DNDC model from 2011 - 2100 years. Climate for future is simulated with RCP 8.5 scenario for understanding the effect of climate change to greenhouse gases emission. Various rice paddy flooding techniques were applied to find proper management for future management. With conventional flooding technique, climate change increase greenhouse gases emission highly. Marginal flooding can decrease large amount of greenhouse gases emission and even it still increases with climate change, it has the smallest increasing ratio. If we suppose the flooding technique will change for best grain yield, dominant flooding technique will be different from conventional flooding to marginal flooding. The management change will reduce greenhouse gases emission. The result of study shows the possibility to increase greenhouse gases emission with climate change and climate change adaptation can show apposite result compared without the adaptation.