• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.322-332
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• 2022

Energy storage capacitors based on dielectric ceramics with superior polarization properties and dielectric constant can provide much higher output power density due to their very fast energy charging/discharging rates, which are particularly suitable for operating pulsed-power devices. For an outstanding energy storage performance of dielectric capacitor, a large recoverable energy density could be derived by introducing a slim polarization-electric field hysteresis loop into dielectric materials by various technical approaches. Many research teams have explored various dielectric capacitor technologies to demonstrate high output power density and ultrafast charging/discharging behavior. This article reviews the recent research progress in high-performance dielectric capacitors for pulsed-power electronic applications.

• Transactions of the Korean hydrogen and new energy society
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• v.7 no.2
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• pp.137-145
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• 1996

The Zr-based $AB_2$ type Laves phase hydrogen storage alloys have some promising properties, long cycle life, high discharge capacity, as electrode materials in reversible metal hydride batteries. However, when these alloys are used as negative electrode for battery, there is a problem that their rate capabilities are worse than those of commercialized $AB_5$ type hydrogen storage alloys. In this work, we tried to develop the Zr-based $AB_2$ type Laves phase hydrogen storage alloys which have high capacity and, especially, high rate capability.

• Korean Institute of Interior Design Journal
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• v.15 no.2 s.55
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• pp.138-149
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• 2006

A museum's collections is fundamental factors to construct important activity of museum performing a role as cultural facility for learning, education and research. Therefore, conservation of collections through appropriate environments is previously established in step of planing a museum. Hereby, the purpose of this study is to set up the classification of collections and suggest a useful guidance of the storage division in a domestic museum. The results of this study are as follows. First, the main factors of deterioration are temperature and relative humidity in a museum storage, so classification of collections should be set up according to the objective standards of these factors. Second, the classification of collections can be performed as follow: the group for nonorganic materials subdivide metal, chinaware, earthenware, and jade stone, the group for organic materials subdivide leather hair paper fabric, bone horn shell mound and wood herbage and the group for composed materials. Third, for storage division of a domestic museum, basically has to consider that it is reasonable to plan $4{\sim}5$ storages in metal, jade stone, chinaware earthenware, and organic materials of $1{\sim}2$ units in case of a serial of history like archaeological, antique museum. And in case of folk relics of modern and contemporary arts are collected, it is reasonable to plan over 5 storages add composed materials to foregoing classification.

• Korean Journal of Materials Research
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• v.31 no.10
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• pp.546-551
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• 2021

To improve ferroelectric properties of PZT, many studies have attempted to fabricate dense PZT films. The AD process has an advantage for forming dense ceramic films at room temperature without any additional heat treatment in low vacuum. Thick films coated by AD have a higher dielectric breakdown strength due to their higher density than those coated using conventional methods. To improve the breakdown strength, glass (SiO₂-Al₂O₃-Y₂O₃, SAY) is mixed with PZT powder at various volume ratios (PZT-xSAY, x = 0, 5, 10 vol%) and coating films are produced on silicon wafers by AD method. Depending on the ratio of PZT to glass, dielectric breakdown strength and energy storage efficiency characteristics change. Mechanical impact in the AD process makes the SAY glass more viscous and fills the film densely. Compared to pure PZT film, PZT-SAY film shows an 87.5 % increase in breakdown strength and a 35.3 % increase in energy storage efficiency.

• Ceramist
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• v.21 no.2
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• pp.49-58
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• 2018

Metal oxide based materials have been widely used to fields of electrochemical applications. Recently, various type of defects from microstructures of metal oxides and their nanocomposites have been raised as the important material design factors for realizing highly improved electrochemical properties. Previous experimental and theoretical works have suggested that controlling the reaction activity and kinetics of the key electrochemical reactions by activated interfaces originating from the defect sites can play an important role in achieving the robust energy storage and conversion. Therefore, this paper focuses on the role of defect-controlled metal oxide materials such as doping, edge-sites, grain boundaries and nano-sized pores for the high performances in energy storage devices and electrocatalysts. The research approaches demonstrated here could offer a possible route to obtain noble ideas for designing the metal oxide materials for the energy storage and conversion applications.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.475-481
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• 2014

Ammonia borane ($NH_3BH_3$), as a source material for energy generation and hydrogen storage, has attracted growing interest due to its high hydrogen content. We have investigated the synthesis of ammonia borane from sodium borohydride ($NaBH_4$) and ammonium chloride ($NH_4Cl$) utilizing a low-temperature process. From our results, we obtained a maximum synthetic yield of 98.2% of ammonia borane complex. The diammoniate diborane (DADB) was detected in about 5~10mol% with in the solid ammonia borane by solid-state $^{11}B$-NMR analysis. The synthesized solid ammonia borane products were studied to characterize hydrogen release upon thermal dehydrogenation.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.91-91
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• 2003

• Food Science and Preservation
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• v.2 no.2
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• pp.277-284
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• 1995

To study the shelf-life of cut cabbage kimchi, we examined the several quality characteristics of cabbage kimchi under various storage temperatures and packing materials. The pH of kimchi extracts were decreased to 4.0 in the condition of storage at 8$^{\circ}C$ during 6 days, at 4$^{\circ}C$ during 18days, 0$^{\circ}C$ during 42 days. The increase patterns of the organic acid were reverse to the changes of pH under the all conditions. The contents of reducing sugar were continuously decreased at 8$^{\circ}C$ , but increased gradually at 0$^{\circ}C$ and 4$^{\circ}C$ storage conditions. The contents of vitamine C were decreased at the early storage but increased to optimum ripening stage of pH 4.2-4.4 and after decreased continuously. The total bacterial cell counts of cabbage kimchi were increased suddenly at the early storage and after decreased gradually. And at the higher storage temperature, the more lactic acid bacteria were. On the results of sensory evaluation of cabbage kimchi at marketable shelf-life, sour taste and sour smell were significant under all experimental conditions by Duncan's multiple range test. On the above all results, we concluded that the marketable shelf-life of cut cabbage kimchi were 42 days, 19 days, 6 days at 0$^{\circ}C$, 4$^{\circ}C$, 8$^{\circ}C$ storage condition respectively.

• Journal of dental hygiene science
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• v.10 no.6
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• pp.459-464
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• 2010

The purpose of this study was to evaluate the physical properties of hydrophilic polyvinyl siloxane impression materials as change of material's storage temperatures. Working time, strain-in-compression, elastic recovery and consistency were tested according to ISO Standard NO. 1563. The results are as followed. 1. Working time decreased in cold storage. 2. Strain-in-compression was different in storage temperatures. Material's strain-in compression in cold temperatures were higher than in room temperature and in incubator. 3. A coefficient of elastic recovery varied by storage temperatures. The rate in cold temperature was the lowest and in incubator was the highest. 4. Consistency of impression substance different in storage temperatures. The extent in cold temperature is the highest and in incubator was the lowest. Statistical analysis(SPSS 14.0k, p>0.05) showed that storage temperature affect to material's physical properties. We recognized that the physical properties of polyvinyl siloxane impression materials were changed according to storage temperature.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.8
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• pp.1183-1188
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• 2008

The present study aimed to determine the effects of different storage materials and storage period on some hatchability traits of Japanese quail (Coturnix coturnix japonica) eggs. A total of 32 male and 102 female quail (twelve weeks of ages) were housed in multiple-bird cages. Eggs laid were divided into three groups with respect to the period of storage (I = 1st, 2nd and 3rd days, II = 6th, 7th and 8th days, III = 12th, 13th and 14th days) prior to incubation. A total of 816 eggs was stored in 3 different storage environments during each storage period (B = no use of any storage material, P = use of perlite, H = use of hay) and kept in environmental conditions, where the temperature was $21^{\circ}C$ and relative humidity was 75%, prior to incubation. Statistical analyses were performed after the exclusion of values pertaining to non-fertile eggs (190 eggs) from the data set. The fertility rate of the eggs in the experiment was 76.7%. In the present study, the influence of storage material and different storage periods on egg weight loss were found to be statistically significant (p<0.01). Upon the comparison of hatchability of fertile eggs values, the influence of storage material was determined to be significant (p<0.05), and the influence of storage period was demonstrated to be significant (p<0.01). The storage materials used were determined not to have any influence on early and late embryonic death rates. Perlite was concluded to be safe for use in the storage of hatching eggs. The extension of the storage period (more than 8 days) resulted in decreased hatchability values of fertile eggs in each group.