• Korean Journal of Materials Research
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• v.31 no.12
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• pp.710-718
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• 2021

Recently, due to high theoretical capacitance and excellent ion diffusion rate caused by the 2D layered crystal structure, transition metal hydroxides (TMHs) have generated considerable attention as active materials in supercapacitors (or electrochemical capacitors). However, TMHs should be designed using morphological or structural modification if they are to be used as active materials in supercapacitors, because they have insulation properties that induce low charge transfer rate. This study aims to modify the morphological structure for high cycling stability and fast charge storage kinetics of TMHs through the use of nickel cobalt hydroxide [NiCo(OH)₂] decorated on nickel foam. Among the samples used, needle-like NiCo(OH)₂ decorated on nickel foam offers a high specific capacitance (1110.9 F/g at current density of 0.5 A/g) with good rate capability (1110.9 - 746.7 F/g at current densities of 0.5 - 10.0 A/g). Moreover, at a high current density (10.0 A/g), a remarkable capacitance (713.8 F/g) and capacitance retention of 95.6% after 5000 cycles are noted. These results are attributed to high charge storage sites of needle-like NiCo(OH)₂ and uniformly grown NiCo(OH)₂ on nickel foam surface.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1307-1311
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• 1998

Optimal packaging methods for the long term storage of salted winter baechu were investigated. Salted baechu was packaged individually in 20 ㎏ unit weight in LDPE (low density polyethylene), HDPE (high density polyethylene), PVC-box and then stored at $0^{\circ}C$ for 8 weeks. During storage, quality index of salted baechu were measured in terms of salinity, pH, reducing sugar content, total cell counts and lactic acid bacterial counts. Salted baechu deteriorated rapidly in PVC-box, and slowly in HDPE but sustained for 8 weeks in LDPE. In all treatment, salted baechu was maintained better at submerged parts in exudate, but deteriorated at emerged parts.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.213-213
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• 2010

Magnetic random access memory (MRAM), based on magnetic tunnel junction (MTJ) and CMOS, is one of the best semiconductor memories because it can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage and high storage density. For the realization of high density MRAM, the etching of MTJ stack with good properties is one of a key process. Recently, there has been great interest in the MTJ stack using MgO as barrier layer for its huge room temperature MR ratio. The use of MgO barrier layer will undoubtedly accelerate the development of MTJ stack for MRAM. In this study, high-density plasma reactive ion etching of MgO films was investigated in an inductively coupled plasma of $Cl_2$/Ar gas mixes. The etch rate, etch selectivity and etch profile of this magnetic film were examined on vary gas concentration. As the $Cl_2$ gas concentration increased, the etch rate of MgO monotonously decreased and etch slop was slanted. The effective of etch parameters including coil rf power, dc-bais voltage, and gas pressure on the etch profile of MgO thin film was explored, At high coil rf power, high dc-bais voltage, low gas pressure, the etching of MgO displayed better etch profiles. Finally, the clean and vertical etch sidewall of MgO films was achieved using $Cl_2$/Ar plasma at the optimized etch conditions.

• Korean Journal of Materials Research
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• v.22 no.3
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• pp.159-167
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• 2012

Hydrogen is in the spotlight as an alternative next generation energy source for the replacement of fossil fuels because it has high specific energy density and emits almost no pollution, with zero $CO_2$ emission. In order to use hydrogen safely, reliable storage and transportation methods are required. Recently, solid hydrogen storage systems using metal hydrides have been under extensive development for application to fuel cell vehicles and fuel cells of MCFC and SOFC. For the practical use of hydrogen on a commercial basis, hydrogen storage materials should satisfy several requirements such as 1) hydrogen storage capacity of more than 6.5wt.% $H_2$, moderate hydrogen release temperature below $100^{\circ}C$, 3) cyclic reversibility of hydrogen absorption/desorption, 4) non toxicity and low price. Among the candidate materials, Li based metal hydrides are known to be promising materials with high practical potential in view of the above requirements. This paper reviews the characteristics and recent R&D trends of Li based complex hydrides, Li-alanates, Li-borohydrides, and Li-amides/imides.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.3-8
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• 2013

Bit patterned media (BPM) storage is one of the promising technologies to overcome the limitations of the conventional magnetic recording. However, there are some problems in a high areal density BPM storage, inter-track interference, inter-symbol interference and noise which are severely degrading performance of the system with reducing the bit error rate. In this paper, we present a simple iterative two-dimensional equalizer based on the contraction mapping theorem to mitigate these adverse effects. Furthermore, we examine that the channel characteristics of the proposed two-dimensional equalizer satisfies the convergence conditions. In the simulation we demonstrate the bit separation characteristics of the one-dimensional equalizer and the two-dimensional equalizer and evaluate the BER performance of the proposed equalizer comparing with the conventional equalizers. According to the results of experiments, the proposed equalizer is an promising equalizer with maintaining proper complexity for a high areal density BPM storage.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.187-187
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• 2003

To examine the effect of packaging method on strawberry, tomato, and plum quality, the rate of weight loss, Hunter a value, decay rate, anthocyanin contents, and microbial (total bacterial counts, mold and yeast, and pseudomonas) changes were determined during storage. Strawberry was packaged with low density polyethylene (LDPE). Tomato and plum were packaged with high density polyethylene film (HDPE). Strawberries, tomatoes, and plums were then stored at 4$^{\circ}C$ and 20$^{\circ}C$, respectively. LDPE package was the most effective on the decrease of decay rate of strawberry and the rate of weight loss for packaged strawberry was lower than that of the non-packaged. HDPE package was the most effective on the rate of weight loss during storage of tomatoes and plums regardless of storage temperature. Hunter a value increased during storage. Anthocyanin contents of plums increased overall with increasing storage time, and plums stored without package were changed more than those with package. Microbial changes of strawberry, tomato, and plum stored at 4$^{\circ}C$ and 20$^{\circ}C$ were monitored during storage. Packaging method did not affect the microbial change, yet temperature did affect the microbial change significantly. These results indicate that storage of these commodities at 4$^{\circ}C$ should be recommended in terms ,of microbial safety as well as quality and shelf-life.

• Korean Journal of Materials Research
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• v.31 no.2
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• pp.68-74
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• 2021

Zinc-ion Batteris (ZIBs) are recently being considered as energy storage devices due to their high specific capacity and high safety, and the abundance of zinc sources. Especially, ZIBs can overcome the drawbacks of conventional lithium ion batteris (LIBs), such as cost and safety issues. However, in spite of their advantages, the cathode materials under development are required to improve performance of ZIBs, because the capacity and cycling stability of ZIBs are mainly influenced by the cathode materials. To design optimized cathode materials for high performance ZIBs, a novel manganese oxide (MnO2) coated graphite sheet is suggested herein with improved zinc-ion diffusion capability thanks to the uniformly decorated MnO2 on the graphite sheet surface. Especially, to optimize MnO2 on the graphite sheet surface, amounts of percursors are regulated. The optimized MnO2 coated graphite sheet shows a superior zinc-ion diffusion ability and good electrochemical performance, including high specific capacity of 330.8 mAh g-1 at current density of 0.1 A g-1, high-rate performance with 109.4 mAh g-1 at a current density of 2.0 A g-1, and remarkable cycling stability (82.2 % after 200 cycles at a current density of 1.0 A g-1). The excellent electrochemical performance is due to the uniformly decorated MnO2 on the graphite sheet surface, which leads to excellent zinc-ion diffusion ability. Thus, our study can provide a promising strategy for high performance next-generation ZIBs in the near future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.576-581
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• 2002

The suspension is a structure that supports reading, writing head in information storage device. In order to develop the information storage device of high track density, it is necessary to study about the suspension. To satisfy operation condition of information storage device, the suspension shape is very important since it correlates to dynamic characteristics. Therefore, it is necessary to analyze the dynamic characteristics by using finite element analysis and to optimize the suspension of information storage device using size optimization and topology optimization. The suspension has various modes according to different kinds of frequency bandwidth. Sway mode and second torsion mode are especially critical among them. In this paper, we investigated method to improve bandwidth of sway and second torsion mode of HDD and ODD suspension by using size optimization and topology optimization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.642-646
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• 2005

We propose an improved partial response maximum likelihood (PRML) detector with the branch value compensation of Viterbi decoder for asymmetric high-density optical channel. Since the compensation value calculated by a survival path is applied to each branch metric, it reduces the detection errors by the asymmetric channel. The proposed PRML detection scheme improves the detection performance on the $2^{nd},\;3^{rd}\;and\;4^{th}$ order PR targets for asymmetric optical recording channel.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1996.10a
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• pp.42-53
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• 1996

Storage methods to suppress growth of transplants and maintain their quality are required for successful commercial transplant production, since peak demand for transplants of flower or vegetable species falls during limited periods in spring and fall, due to the seasonal nature of the horticulture industry. Plug seedlings, probably due to their high planting density and limited rhizosphere, easily elongated or overgrown during the holding period before the market or greenhouse space is available. (omitted)