• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.133-140
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• 2019

Two-dimensional (2D) ultrathin molybdenum dichalcogenides $MoS_2$ has gained a great deal of attention in energy conversion and storage applications because of its unique morphology and property. The 2D $MoS_2$ nanosheets provide a high specific surface area, 2D charge channel, sub-nanometer thickness, and high conductivity, which lead to high electrochemical performances for energy storage devices. In this paper, an overview of properties and synthetic methods of $MoS_2$ nanosheets for applications of supercapacitors and rechargeable batteries is introduced. Different phases triangle prismatic 2H and metallic octahedral 1T structured $MoS_2$ were characterized using various analytical techniques. Preparation methods were focused on top-down and bottom-up approaches, including mechanical exfoliation, chemical intercalation and exfoliation, liquid phase exfoliation by the direct sonication, electrochemical intercalation exfoliation, microwave-assisted exfoliation, mechanical ball-milling, and hydrothermal synthesis. In addition, recent applications of supercapacitors and rechargeable batteries using $MoS_2$ electrode materials are discussed.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.289-292
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• 1999

Random reference wave can be used to enhance selectivity and storage density of holograms. Hologram recording schemes with random reference waves generated by using a ground glass or various types of optical fibers are discussed. The random reference waves are also suitable for hybrid multiplexing methods.

• Korean Journal of Pharmacognosy
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• v.50 no.4
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• pp.312-317
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• 2019

In order to obtain basic data on the shelf life of Epimedii Herba (EH), a physicochemical characteristics including weight loss rate, loss on drying, ash, acid-insoluble ash, and quantitative determination were evaluated to compare the data by packaging methods including general (G), general + silica gel (GS), alumium (AL), and alumium + silica gel (ALS) packaging and storage periods (0-66 months). All physicochemical analyzes were conducted using the method of "The Korean Pharmacopoeia (KP) 9^th edition". As a result, weight loss rate (%), loss on drying (%), ash (%), acid-insoluble ash (%) of EH according to the packaging methods and storage periods were -0.27-4.73%, 3.06-9.35%, 5.48-7.37%, and 0.45-0.99, respectively. In the quantitative analysis of icariin, the marker compound of EH using high-performance liquid chromatography, the initial content was 0.44% at 0 month in all packaging methods. After that, the result of analyzing the content of icariin every 6 months was detected 0.44-1.18%. All of the above results satisfied the acceptance criteria for loss on drying, ash, acid-insoluble ash, and quantification contained in the KP. This study can be used as a basic data for establishing the packaging method and shelf life of EH.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.2
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• pp.57-61
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• 2015

Current research and development efforts and other projects for energy storage systems (ESS) have recently been gaining attention. This is due to the many applications where ESS, particularly batteries, can be used. Among these are peak shaving, frequency regulation, and stabilization of renewable energy output. KEPCO has completed the construction and demonstration of a 4-MW battery energy storage system (BESS) located in Jeju City to verify its practicability in the power grid. KEPCO Research Institute has also been developing technology for the commercialization of BESS, and has been conducting a trial run of a 52-MW ESS (28MW + 24MW of Seo-Anseong and Shin-Yongin substations) constructed in 2014 for frequency regulation. This paper discusses the development of operation methods, as well as an operation user interface, for the safe operation and monitoring of BESS used for frequency regulation in a power system. Included are operation and simulation methods for various normal and transient frequency situations that can be experienced by a power system. Also discussed are the results obtained after applying these methods to the 4-MW BESS and the 52-MW ESS, both used for frequency regulation. The technology in this paper will be applied to 500MW ESS for frequency regulation of KEPCO by 2017. It is expected that this technology helps a safe and reliable operation and control of ESS for frequency regulation through its continuous upgrade.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.3
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• pp.231-236
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• 2022

The research was aimed to improve pre-harvest methods to maintain marketability in postharvest leaf lettuce. In this study, the effect of hydroponics on the growth and post-harvest storage characteristics of 'Chongchima' lettuce grown in peat mass medium hydroponic system using a non-powered culture device or deep water culture (DWC) was evaluated. There was no difference in fresh weight, leaf number, SPAD, moisture content, and C/N ratio between peat moss growing medium hydroponic and DWC methods except plant height. It was found that lettuce cultivation by a nonpowered hydroponics method is easier than the existing DWC. The quality parameters, such as fresh weight loss, SPAD value, and general appearance of lettuce were investigated after harvest. There was no significant difference in fresh weight loss and general appearance during storage of lettuce by the hydroponics methods. However, with the increased storage time of SPAD, which is related to chlorophyll content, was slightly higher in peat moss medium hydroponic was than DWC. When crops such as lettuce are grown under favorable conditions without any agronomic abnormalities, it is suggested that post-harvest storage is not significantly affected by peat moss growing medium hydroponic and DWC.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2061-2065
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• 2008

In the conventional operation of ice-storage system based on operator's experience and judgement, the failure in forecast of cooling load occurs frequently due to operator's misjudgement and unskilled operation. This study presents the method of constructing self-organizing fuzzy models which forecast tomorrow temperature, humidity and cooling load periodically for economic and efficient operation of ice-storage system. To check the effectiveness and feasibility of the suggested algorithm, the actual example for forecasting temperature, humidity and cooling load of ice- storage system in KEPCO training institute, Sokcho, is examined. The computer simulation results show that the accuracy of temperature, humidity, cooling load forecast of the suggested algorithm is higher than that of the conventional methods.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.13 no.1
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• pp.5-8
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• 2007

The effects of packaging conditions on freshness extension of cucumber were investigated during 24-day storage temperatures $18^{\circ}C$ and $10^{\circ}C$. The storage life of cucumbers was influenced by both packaging methods (corrugated cardboard vs EPS box) and temperatures during storage. The fresh weigh, vitamin C content and Chlorophyll of cucumbers were decreased, while yellowing of cucumber peel was increased during storage. The change of vitamin C content was influenced by both packaging method and temperature during storage. The EPS box and low temperature were revealed to be effective treatments to extend the storability or cucumber fruit.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.134-139
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• 2002

This paper presents a servo design method for high track-density hard disk drives, in which the plant time delay, mainly due to the processor computation time, is taken into account. The key idea behind the proposed design method is to incorporate the delay model into the output equation of the state-space representation for the plant model; thereby, the delay is accounted for by a standard state observer in a natural manner, with simplified state equations as compared to those for conventional methods. The results from practical application confirm that the proposed method is quite effective in realizing a high-bandwidth servo system in hard disk drives.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.1
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• pp.64-70
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• 2008

This paper briefly discusses the main sources of errors and their solutions for measuring hydrogen uptake from gas phase by the Sieverts technique. Correction of volumetric errors of apparatus, density of hydrogen storage material, estimation of temperature gradient are investigated. Systematic errors and the change of density of the host material according to the pressure have been the subject of much controversy in recent years. We considered the standard ball calibration, temperature gradient distribution, pretreatment of hydrogen storage materials to minimize errors. We could lessen the miscalculations after applying those methods to Equilibrium pressure-composition isotherm data.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.03a
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• pp.120-121
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• 2009

We prepared polymer-PCM gels such as prepared frozen gel from polypropylene and n-Paraffin for thermal storage and release materials, their basic properties and possible applications especially in latent heat storage. The preparation methods are used to melting method and absorption method respectively. The composition and properties of prepared frozen gels from polypropylene and n-Paraffin were observed by DSC, FT-IR spectra, ARES and Elemental analysis. We can prepare frozen gels in different temperature for latent heat storage materials as controlling composition of phase change material as well as using different incorporating phase change materials. These frozen gels can be used to latent heat storage materials for several applications.