• Particle and aerosol research
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• v.5 no.2
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• pp.37-43
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• 2009

Particulate matter (PM) is one of the major indoor air pollutants especially in the subway station in Korea. In order to remove PM in the subway station, several kinds of PM removal system such as roll-filter, auto-washable air filter, demister, and electrostatic precipitator are used in the air handling unit (AHU) of subway stations. However, those systems are prone to operation and maintenance problems since the filter-regeneration unit consisting of electrical or water jet parts might malfunction due to the high load of particulates unless the filter medium is periodically replaced. In this study, the use of axial-flow cyclone was proposed for particulate filter unit in the AHU for its low operation and maintenance cost. Novel shape of axial-flow cyclone was designed by using computational fluid dynamics (CFD). The shape of vortex vane was optimized in terms of pressure drop and tangential velocity. In addition, CFD analysis was validated experimentally through the pressure drop measurement of mock-up model. We found that pressure drop and tangential velocity of fluid through the axia-flow cyclone was significantly affected by the rotating degree of vortex vane and the numerical prediction of pressure drop agreed well with experimental measurement.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.3
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• pp.176-185
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• 2018

With the recent development of manufacturing technology and the diversification of consumer needs, not only the process and quality control of production have become more complicated but also the kinds of information that manufacturing facilities provide the user about process have been diversified. Therefore the importance of big data analysis also has been raised. However, most small and medium enterprises (SMEs) lack the systematic infrastructure of big data management and analysis. In particular, due to the nature of domestic manufacturing companies that rely on foreign manufacturers for most of their manufacturing facilities, the need for their own data analysis and manufacturing support applications is increasing and research has been conducted in Korea. This study proposes integrated analysis platform for process and quality analysis, considering manufacturing big data database (DB) and data characteristics. The platform is implemented in two versions, Web and C/S, to enhance accessibility which perform template based quality analysis and real-time monitoring. The user can upload data from their local PC or DB and run analysis by combining single analysis module in template in a way they want since the platform is not optimized for a particular manufacturing process. Also Java and R are used as the development language for ease of system supplementation. It is expected that the platform will be available at a low price and evolve the ability of quality analysis in SMEs.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.905-911
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• 1998

Damping is a property for materials and systems to dissipate energy during periodic deformations. Generally, damping causes stiff decrease in amplitudes and shifts in phases. Also, even at resonance, amplitudes are substantially attenuated. This phenomenon of damping helps in reducing stresses developed during vibrations and consequently improves fatigue lives of materials. In this work internal damping and complex moduli are experimentally determined. An impulse technique is utilized in experiments and cantilever beams are selected as test subjects for the measurements of flextural vibrations since the beams lend themselves easily as simplistic ideal models. A resonance method is employed to determine resonance frequencies which are utilized to compute storage moduli. Also, loss moduli are evaluated from damping capacities and storage moduli. The storage and loss moduli combined yield complex moduli. Finally internal damping is evaluated from bandwidth technique, the real component of the transfer function.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.20-26
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• 2014

It is essential to consider the effect of blade deformation in order to design a better tidal stream turbine being operated in off-design condition. Flow load causes deformation on the blade, and the deformation affects the turbine performance. In the present study, CFD analysis procedures were developed to predict open water performance of horizontal axis tidal stream turbine (HATST). The developed procedures were verified by comparing the results with existing experimental results. Fluid-structure interaction (FSI) analysis method, based on the verified CFD procedure, have been carried out to estimate the turbine performance for a turbine with flexible composite blades, and then the results were compared with those for rigid blades.

• Nuclear Engineering and Technology
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• v.42 no.1
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• pp.17-36
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• 2010

In this study, we compare the mass release rates of radionuclides(1) from waste forms arising from the KIEP-21 pyroprocessing system with (2) those from the directly-disposed pressurized-water reactor spent fuel, to investigate the potential radiological and environmental impacts. In both cases, most actinides and their daughters have been observed to remain in the vicinity of waste packages as precipitates because of their low solubility. The effects of the waste-form alteration rate on the release of radionuclides from the engineered-barrier boundary have been found to be significant, especially for congruently released radionuclides. the total mass release rate of radionuclides from direct disposal concept is similar to those from the pyroprocessing disposal concept. While the mass release rates for most radionuclides would decrease to negligible levels due to radioactive decay while in the engineered barriers and the surrounding host rock in both cases even without assuming any dilution or dispersal mechanisms during their transport, significant mass release rates for three fission-product radionuclides, $^{129}I$, $^{79}Se$, and $^{36}Cl$, are observed at the 1,000-m location in the host rock. For these three radionuclides, we need to account for dilution/dispersal in the geosphere and the biosphere to confirm finally that the repository would achieve sufficient level of radiological safety. This can be done only after we have known where the repository site would by sited. the footprint of repository for the KIEP-21 system is about one tenth of those for the direct disposal.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.2
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• pp.195-201
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• 2016

Hyssopus officinalis is a herbaceous plant of the genus Hyssopus. Due to its properties as an antiseptic, cough reliever and expectorant, it is commonly used as an aromatic herb and medicinal plant. This study was performed to investigate the anti-oxidative and anti-melanogenic properties of Hyssopus officinalis extracts (HE) using in vitro assays and cell culture systems. As a result, HE showed higher DPPH and ABTS radicals scavenging activity in a dose-dependent manner. Also, HE inhibited the prodution of intracellular ROS and melanin contents in B16F10 melanoma cell as well as tyrosinase activity. We also found that HE inhibit mRNA expression of MITF, tyrosinase and TRP-2 gene. These findings suggest that HE may be beneficial for preventing oxidative damage and melanogenesis of skin.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1700-1709
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• 2019

Recently, many researches have been under way to develop systems (services) to support the safety navigation of ships, and in these studies, common difficulties have been encountered in assessing the usefulness and effectiveness of the developed system. To solve these problems, we propose the DEVS-based ship navigation modeling and simulation technique. Following the preceding study, we analyze the COLREG rules and reflected to officer and helmsman agent models for decision making. Also we propose estimation and interpolation techniques to adopt the motion characteristics of the actual vessel to simulation. In addition, we implement the navigation simulation system to reflect the designed proposed methods, and we present five-scenarios to verify the developed simulation system. And we conduct simulations according to each scenario and the results were reconstructed. The simulation results confirm that the components modelled in each scenario enable to operate according to the navigation relationships.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.5
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• pp.1433-1449
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• 2023

In recent years, the rapid development of social networks has led to a rapid increase in the amount of information available on the Internet, which contains a large amount of sensitive information related to pornography, politics, and terrorism. In the aspect of sensitive image detection, the existing machine learning algorithms are confronted with problems such as large model size, long training time, and slow detection speed when auditing and supervising. In order to detect sensitive images more accurately and quickly, this paper proposes a multiclassification sensitive image detection method based on lightweight Convolutional Neural Network. On the basis of the EfficientNet model, this method combines the Ghost Module idea of the GhostNet model and adds the SE channel attention mechanism in the Ghost Module for feature extraction training. The experimental results on the sensitive image data set constructed in this paper show that the accuracy of the proposed method in sensitive information detection is 94.46% higher than that of the similar methods. Then, the model is pruned through an ablation experiment, and the activation function is replaced by Hard-Swish, which reduces the parameters of the original model by 54.67%. Under the condition of ensuring accuracy, the detection time of a single image is reduced from 8.88ms to 6.37ms. The results of the experiment demonstrate that the method put forward has successfully enhanced the precision of identifying multi-class sensitive images, significantly decreased the number of parameters in the model, and achieved higher accuracy than comparable algorithms while using a more lightweight model design.

• Journal of Bio-Environment Control
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• v.32 no.2
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• pp.106-114
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• 2023

With rising concerns about pesticide spray drift by aerial application, this study attempt to evaluate aerodynamic property and collection efficiency of spray drift according to the leaf area index (LAI) of crop for preventing undesirable pesticide contamination by the spray-drift tunnel experiment. The collection efficiency of the plant with 'Low' LAI was measured at 16.13% at a wind speed of 1 m·s^-1. As the wind speed increased to 2 m·s^-1, the collection efficiency of plant with the same LAI level increased 1.80 times higher to 29.06%. For the 'Medium' level LAI, the collection efficiency was 24.42% and 43.06% at wind speed of 1 m·s^-1 and 2 m·s^-1, respectively. For the 'High' level LAI, it also increased 1.24 times higher as the wind speed increased. The measured results indicated that the collection of spray droplets by leaves were increased with LAI and wind speed. This also implied that dense leaves would have more advantages for preventing the drift of airborne spray droplets. Aerodynamic properties also tended to increase as the LAI increased, and the regression analysis of quadric equation and power law equation showed high explanatory of 0.96-0.99.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.4
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• pp.64-72
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• 2008

Researchers nowadays are trying to implement u-Healthcare (ubiquitous Healthcare) systems for real-time monitoring and analysis of patients' status through a low-cost and low-power wireless sensor network. u-Healthcare system has an aim to provide reliable and fast medical services for patients regardless of time and space by transmitting to doctors a large quantity of vital signs collected from sensor networks. Existing u-Healthcare systems can merely monitor patients' health status. However, it is not easy to derive physiologically meaningful results by analyzing rapidly vital signs through the existing u-Healthcare systems. We introduce a Grid computing technology for deriving the results by analyzing rapidly the vital signs collected from the sensor network. Since both sensor network and Grid computing use different protocols, a gateway is needed. In addition, we also need to construct a gateway which includes the functions such as an efficient management and control of the sensor network, real-time monitoring of the vital signs and communication services related to the Grid network for providing u-Healthcare services effectively. In this paper, to build an advanced u-Healthcare system by using these two technologies most efficiently, we design and present the results to implement a SensorGrid gateway which connects transparently the sensor network and the grid network.