• Journal of the Korean Society of Combustion
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• v.11 no.2
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• pp.28-36
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• 2006

A constant volume combustion chamber was used to investigate the combustion characteristics. of homogeneous charge of methane-air mixture under various initial pressure, equivalence ratio and ignition times. The constant volume combustion chamber(CVCC) mostly has been studied by the experiments of visualization until now. So it is needed the numerical analysis of fluid and combustion characteristics in chamber by the more detail simulation. In this paper, the numerical analysis is tried to approach basically the homogeneous charge combustion phenomena under the various conditions, and the combustion phenomena in chamber is numerically analyzed by the commercial FIRE code. As a results, the combustion phenomena which were mean temperature, OH radical and reaction rate in chamber were investigated and it showed that the smallest flame growth occurs for the lean state and the increase of initial charged pressure condition due to the reduced OH radical.

• Journal of Biomedical Engineering Research
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• v.11 no.2
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• pp.203-208
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• 1990

A possible asymmetry in airway inertance was modeled based on previously reported radiographic visualization data of the airway wall fluctuation in intact dogs. Effects of asymmetric Inertance on mean lung volume during high frequency ventilation (HFV) were evaluated in terms of mean inertive pressure drop across the airways. It was found that a negligible inertlve pressure drop was expected ($<1{\;}cmH_20$) in normal subjects, while a sig- nificant rise in mean alveolar pressure compared to mean mouth pressure by approximately $3{\;}cmH_20$ was resulted for about 40% airway fluctuation representing bronchoconstriction state by Histamine induction. These results demonstrate that asymmetric Inertance could lead patients with airway diseases to a significant lung hyperinflation (LHI), and bronchodilation treatment is recommended prior to applying HFV to prevent those patients from a possible barotrauma.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.183-196
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• 1997

Gas flow field within the cylinder which is called a tumble flow is important factor in improving lean combustion stability. In this study, steady state flow tests were performed to quantify tumble ratio of flowfields generated by a tumble intensifying valve(TIV). In addition, velocity and fluctuation profiles in an intake port and flowfields in th cylinder were inspected using a hotwire anemometer and a laser light sheet method with various TIV configurations. These experimental results show that installated TIV has a great effect on flow field distribution in an intake port and test effects enhance a tumble flow in the cylinder.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.126-127
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• 2018

Rebar work is important in terms of cost and process of reinforced concrete construction along with formwork and concrete construction, and the quality of reinforced concrete construction has a great influence on the safety and durability of the structure. Therefore it is important to thoroughly inspect the steel reinforcement after casting the concrete because it is difficult to confirm the actual condition of the reinforcement. The purpose of this study is to develop an augmented reality system to visualize the records of bar placing work, which is increasingly utilized in the construction field. In order to improve maintenance of reinforced concrete, this study suggests a plan to effectively manage the drawing information including the structural drawing, the placing drawing, and the photographed image at the construction and inspection stage, and develop a system that utilizes augmented reality technology that can display the state of the inside of a concrete structure by superimposing it on actual environment.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2733-2737
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• 2008

The present study numerically investigates three-dimensional laminar flow past a rotating circular cylinder placed in a uniform stream. For the purpose of a careful analysis of the modification of flow by the effect of the rotation on the flow, numerical simulations are performed at a various range of rotational speeds($0{\leq}{\alpha}{\leq}2.5$) at one Reynolds number of 300. As $\alpha$ increases, flow becomes stabilized and finally a steady state beyond the critical rotational speed. The 3D (three dimensional) wake mode of the stationary cylinder defined at this Reynolds number has been disorganized according to $\alpha$, which were observed by the visualization of 3D vortical structures. The variation of the Strouhal number is significant when the wake pattern is changed according to the rotational speed. As $\alpha$ increases, the lift increases, whereas the drag decreases.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.4
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• pp.272-289
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• 2004

The spatial resolution of local weather and climate information for agronomic practices exceeds the current weather service scale. To supplement the insufficient spatial resolution of official forecasts and observations, gridded climate data are frequently generated. Most ecological models can be run using gridded climate data to produce ecosystem responses at landscape scales. In this lecture, state of the art techniques derived from geospatial climatology, which can generate gridded climate data by spatially interpolating point observations at synoptic weather stations, will be introduced. Removal of the urban effects embedded in the interpolated surfaces of daily minimum temperature, incorporation of local geographic potential for cold air accumulation into the minimum temperature interpolation scheme, and solar irradiance correction for daytime hourly temperature estimation are presented. Some experiences obtained from their application to real landscapes will be described.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.35-38
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• 2002

Variations of temperature and velocity fields in a Hele-Shaw Convection Cell (HSC) were measured using a holographic interferometry and PIV technique with varying Rayleigh number. Experimental results show a steady flow pattern at low Rayleigh numbers and a time-dependent periodic flow at high Rayleigh numbers. Two different measurement methods of holographic interferometry, double-exposure method and real-time method, were employed to measure the temperature field variations of HSC convective flow. In the double-exposure method, unwanted waves can be eliminated and reconstruction images are clear, but transient flow structure cannot be observed clearly. On the other hand, transient flow can be observed and reconstructed well using the real-time method. PIV results show that flow inside the HSC is periodic and the oscillating state is well matched with the temperature field results. The holographic interferometry and PIV techniques employed in this study are useful for analyzing the unsteady convective thermal fluid flows.

• Proceedings of the KIEE Conference
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• summer
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• pp.64-66
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• 2004

Due to the involvedness of power system, the analysis of power system is hard to make out. In some cases, visualized analysis results help to understand the power system effectively. In this paper, 3D graphic is used to visualize the power system, and chains of power system's changes are represented using the result of HyperSim, a real-time simulator. We represent states of each bus by changing height and colors of cylinder. The current of transmission lines and the angle of generators are represented by the size of pyramids and the drection of arrows respectively. Results of power system analysis are represented more easily and more intuitably using the visualization.

• Journal of Information Processing Systems
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• v.15 no.3
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• pp.500-519
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• 2019

The blooming of social media has simulated interest in sentiment analysis. Sentiment analysis aims to determine from a specific piece of content the overall attitude of its author in relation to a specific item, product, brand, or service. In sentiment analysis, the focus is on the subjective sentences. Hence, in order to discover and extract the subjective information from a given text, researchers have applied various methods in computational linguistics, natural language processing, and text analysis. The aim of this paper is to provide an in-depth up-to-date study of the sentiment analysis algorithms in order to familiarize with other works done in the subject. The paper focuses on the main tasks and applications of sentiment analysis. State-of-the-art algorithms, methodologies and techniques have been categorized and summarized to facilitate future research in this field.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.6
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• pp.2115-2127
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• 2021

Although significant progress has been made in synthesizing visually realistic face images by Generative Adversarial Networks (GANs), there still lacks effective approaches to provide fine-grained control over the generation process for semantic facial attribute editing. In this work, we propose a novel cross channel self-attention based generative adversarial network (CCA-GAN), which weights the importance of multiple channels of features and archives pixel-level feature alignment and conversion, to reduce the impact on irrelevant attributes while editing the target attributes. Evaluation results show that CCA-GAN outperforms state-of-the-art models on the CelebA dataset, reducing Fréchet Inception Distance (FID) and Kernel Inception Distance (KID) by 15~28% and 25~100%, respectively. Furthermore, visualization of generated samples confirms the effect of disentanglement of the proposed model.