• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.300-309
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• 2014

Objectives: The objective of this study is to evaluate microbial exposure hazards in the metal-working fluids(MWF) handling industry. Methods: Air quality parameters(airborne bacteria, fungi, endotoxin and oil mist) and bulk MWF in storage tanks were evaluated at 54 points at nine sites in South Korea. Results: The geometric means(GM) of culturable airborne bacteria, fungi, endotoxin and oil mist concentration were $133CFU/m^3$(n=376, range $7{\sim}6,510CFU/m^3$), $159CFU/m^3$(n=381, range $7{\sim}8,469CFU/m^3$), $8.06EU/m^3$(n=103, range $0.34{\sim}280.4EU/m^3$) and $0.20mg/m^3$(n=104, range $0.01{\sim}2.87mg/m^3$), respectively. The ratio of indoor to outdoor concentration was 2.7 for bacteria, 6.1 for endotoxin, and 4.8 for oil mist. Even though average airborne bacteria concentration did not exceed recommended exposure limits($1,000CFU/m^3$), MWF in the storage tanks was highly contaminated with bacteria(arithmetic mean $2.1{\times}10^6CFU/ml$) and exceeded recommended bacteria limits($10^5CFU/ml$). Conclusions: It is necessary for MWF handling workplaces to conduct periodical biohazard inspection of MWF storage tanks. Additionally, further research may be necessary to establish biological occupational exposure limits.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.5
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• pp.2310-2345
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• 2017

With the emergence of the Internet of Things (IoT) the world is projecting towards a scenario where every object in the world (including humans) acts as a sender and receiver of data and if we were to see that concept mature we would soon be talking of billions more users of the cloud networks. The cloud technology is a very apt alternative to permanent storage when it comes to bulk storage and reporting. It has however shown weaknesses concerning real-time data accessibility and processing. The bandwidth availability of the cloud networks is limited and combined with the highly centralized storage structure and geographical vastness of the network in terms of distance from the end user the cloud just does not seem like a friendly environment for real-time IOT data. This paper aims at highlighting the importance of Flavio Bonomi's idea of Fog Computing which has been glamorized and marketed by Cisco but has not yet been given a proper service architecture that would explain how it would be used in terms of various service models i-e IaaS, PaaS and SaaS, of the Cloud. The main contribution of the paper would be models for IaaS, PaaS and SaaS for Fog environments. The paper would conclude by highlighting the importance of the presented models and giving a consolidated overview of how they would work. It would also calculate the respective latencies for fog and cloud to prove that our models would work. We have used CloudSim and iFogSim to show the effectiveness of the paradigm shift from traditional cloud architecture to our Fog architecture.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.622-628
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• 2014

This paper presents the SOC-based control strategy of BESS(Battery Energy Storage System) for providing power system frequency regulation in the bulk power systems. As the life cycle of BESS would be shortened by frequent changes of charge and discharge required for frequency regulation in a steady state, the proposed algorithm operates BESS within a range of SOC where its life cycle can be maximized. However, during a transient period of which occurrence frequency is low, BESS would be controlled to use its full capacity in a wider range of SOC. In addition, each output of multiple BESS is proportionally determined by its SOC so that the balance in SOC of multiple BESS can be managed. The effectiveness of the proposed control strategy is verified through various case studies employing a test system. Moreover, the control result of BESS with the measured frequency from a real system shows SOC of BESS can be maintained within a specific range although the frequency deviation is biased.

• Journal of Hydrogen and New Energy
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• v.32 no.6
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• pp.565-572
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• 2021

Hydrogen is currently produced from natural gas reforming or industrial process of by-product over than 90%. Additionally, there are green hydrogens based on renewable energy generation, but the import of green hydrogen from other countries is being considered due to the output variability depending on the weather and climate. Due to low density of hydrogen, it is difficult to storage and import hydrogen of large capacity. For improving low density issue of hydrogen, the gaseous hydrogen is liquefied and stored in cryogenic tank. Density of hydrogen increase from 0.081 kg/m³ to 71 kg/m3 when gaseous hydrogen transfer to liquid hydrogen. Density of liquid hydrogen is higher about 800 times than gaseous. However, since density and boiling point of liquid hydrogen is too lower than liquefied natural gas approximately 1/6 and 90 K, to store liquid hydrogen for long-term is very difficult too. To overcome this weakness, this paper introduces storage method of hydrogen based on liquid/solid (slush) and facilities for producing slush hydrogen to improve low density issue of hydrogen. Slush hydrogen is higher density and heat capacity than liquid hydrogen, can be expected to improve these issues.

• Korean Journal of Medicinal Crop Science
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• v.25 no.2
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• pp.89-94
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• 2017

Background: The purpose of improving the quality of oriental medicinal herbs is to contribute to the improvement of the income of farm. The present study investigated the effect of reasonable drying methods, different storage conditions and packageing materials on quality and stability of Scutellaria baicalensis Georgi and for developing GAP (good agricultural practice) guide book. Methods and Results: Three methods of drying Scutellaria baicalensis roots produced over two years were used to estimate loss rate owing to drying, storage, and packaging. The methods of drying were categorized into natural drying (36 - 60 h by sunshine), drying with heat dryer (2 - 10 h), or drying with gas bulk dryer (2 - 10 h). After cleaning, and initial drying for a few days under controlled temperature conditions, the second phase of drying was carried out at 35, 45 and $55^{\circ}C$. Changes in hunter color values and quality under the two studied storage treatments (at $20^{\circ}C$ indoors and at $4^{\circ}C$ in a refigerator) were evaluated. Storage period for 60, 120, and 180 days in three packaging materials, PE (polyethylene package), PP (polypropylene gunnysack), and WP (watertight packing paper) were studied. Conclusions: Initial cleaning, reasonable gas drying and hot air drying, and drying in an oven at 35 and $45^{\circ}C$ after cutting the roots resulted in the lowest loss rates in S. Baicalensis root. Hunter color valuse indicated that stroage of dry roots at room temperature was better than PP packaging, and that cold stroage was better than PE packaging for long-term stability.

• Journal of Hydrogen and New Energy
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• v.25 no.6
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• pp.602-608
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• 2014

The sequence of bond overlap population of metal hydrogen binding is in Al-H > Fe-H > Zr-H > V-H. This results shows the binding energy of Al-H is the biggest in this metals (Al, Fe, Zr, and V) and hydrogen interaction. The Vanadium-hydrogen binding shows the weakest binding energy compared to other metals and it causes easy hydrogen desorption from the corresponding metals. The net charge of Al-H show the biggest value of 0.2248 and the severe localizations of electrons around aluminum and imply strongest covalent binding nature in these metals. This study is applicable to the purification of hydrogen in other bulk gas.

• Journal of Environmental Science International
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• v.4 no.3
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• pp.197-206
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• 1995

Surface heat balance of the northern sea of Cheju Island for summer in 1993 and 1994 is analyzed using the observation data obtained by Marine Research Institute, Cheju National University. Each flux elements at the sea surface is derived from the marine meteorological reports with application of an aerodynamical bulk method for the turbulent heat fluxes, and empirical formulae for the long-wave radiation heat fluxes. The flux divergence of oceanic heat transport and the rate of heat storage in the ocean are estimated as residual. The features of the surface heat balance are mainly decided by the solar radiation flux and the latent heat flux for 199B. But the Bowen Ratios were large for 1993. This means that the sensible heat fluxes were nearly equal to the latent heat fluxes for 1993. In this period, mean flux divergence of oceanic heat transport is about 130 W/$m^2$.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.293-324
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• 1996

Compact solid-state blue laser have great potential for use in optical data storage, laser beam printing, particle countering, reprographics, holography, and fluorescent bioanalysis. We report recent progresses in qualities of LiB3O5 and K3Li2(TaxNb1-x)5O15 nonlinear crystals which are essential in manufacturing bulk-type blue SHG devices. We also review newly developed violet-blue laser, 20 mW output, using intracavity frequency doubling of a diode laser pumped Cr:LiSrAlF6 laser with low loss LiB3O5 crystal as a frequency doubler.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.9
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• pp.442-445
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• 2006

In order to realize the commercial application of HTSC materials, it is necessary to develop the fabrication process of high Tc oxide superconductor materials with desired shape and for practical application and high critical current density as well as good mechanical strength which can withstand high lorenz force generated at high magnetic field. Much studies have been concentrated to develop the fabrication technique for high critical current density but still there are a lot of gap which should be overcome for large scale application of HTSC materials at liquid nitrogen temperature. Recently some new fabrication techniques have been developed for YBaCuO bulk superconductor with high mechanical strength and critical current density. In this project, the establishment of fabrication condition and additive effects of second elements were examined so as to improve the related properties to the practical use of YBaCuO superconductor, and we reported the production of the YBaCuO high Tc superconductor by the pyrolysis method.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.3-6
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• 2011

The utilization of gas as ship fuel requires a new set of regulations by IMO and society of classification. Maritime Safety Committee(MSC) and the subcommittee Bulk-Liquids and Gases(BLG) in IMO developed "Interim Guidelines on Safety for Natural Gas-fueled Engine Installation in Ships(Res.MSC.285(86))" for the use of natural gas in internal combustion engine. According to the requirement of Res.MSC.285(86) for natural gas-fueled engine installations in ships, several parts of ships should follow safety criteria in terms of Fuel bunkering, Gas safe Machinery spaces, Gas Fuel Storage and etc. In this thesis, details of the IGF code shall be described and development of the IGF code in IMO shall be illustrated.