• Clean Technology
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• v.14 no.3
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• pp.171-175
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• 2008

The effect of the addition of $Al^{3+}$ dopant on the electrochemical characteristics of $Li_{4}Ti_{5}O_{12}$ was investigated. $Li_{4}Ti_{5}O_{12}$ is known as a 2ero-strain material, and $Li_{3.95}Al_{0.15}Ti_{4.9}O_{12}$ has been manufactured by solid-state reaction with high energy ball milling (HEBM). The samples were heated at 800, 900 and $1000^{\circ}C$ in electric furnace. The structural and surface structures were measured by XRD (X-ray diffraction) and SEM (scanning electron microscopy). Cut-off voltage of charge/discharge cycles was $1.0{\sim}3.0 V$ to investigate reversible capacity, cycle stability and plateau voltage. The reversible capacity of $Li_{3.95}Al_{0.15}Ti_{4.9}O_{12}$ was 138 mAh/g.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.559-563
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• 2015

Monitor of All-sky X-ray Image (MAXI) is a Japanese X-ray all-sky surveyer mounted on the International Space Station (ISS). It has been scanning the whole sky since 2009 during every 92-minute ISS rotation. X-ray transients are quickly found by the real-time nova-search program. As a result, MAXI has issued 133 Astronomer's Telegrams and 44 Gamma-ray burst Coordinated Networks so far. MAXI has discovered six new black holes (BH) in 4.5 years. Long-term behaviors of the MAXI BHs can be classified into two types by their outbursts; a fast-rise exponential-decay type and a fast-rise flat-top one. The slit camera is suitable for accumulating data over a long time. MAXI issued a 37-month catalog containing 500 sources above a ~0.6 mCrab detection limit at 4-10 keV in the region ${\mid}{b}{\mid}$ > $10^{\circ}$. The SSC instrument utilizing an X-ray CCD has detected diffuse soft X-rays extending over a large solid angle, such as the Cygnus super bubble. MAXI/SSC has also detcted a Ne emission line from the rapid soft X-ray nova MAXI J0158-744. The overall shapes of outbursts in Be X-ray binaries (BeXRB) are precisely observed with MAXI/GSC. BeXRB have two kinds of outbursts, a normal outburst and a giant one. The peak dates of the subsequent giant outbursts of A0535+26 repeated with a different period than the orbital one. The Be stellar disk is considered to either have a precession motion or a distorted shape. The long-term behaviors of low-mass X-ray binaries (LMXB) containing weakly magnetized neutron stars are investigated. Transient LMXBs (Aql X-1 and 4U 1608-52) repeated outbursts every 200-1000 days, which is understood by the limit-cycle of hydrogen ionization states in the outer accretion disk. A third state (very dim state) in Aql X-1 and 4U 1608-52 was interpreted as the propeller effect in the unified picture of LMXB. Cir X-1 is a peculiar source in the sense that its long-term behavior is not like typical LMXBs. The luminosity sometimes decreases suddenly at periastron. It might be explained by the stripping of the outer accretion disk by a clumpy stellar wind. MAXI observed 64 large flares from 22 active stars (RS CVns, dMe stars, Argol types, young stellar objects) over 4 years. The total energies are $10^{34}-10^{36}$ erg $s^{-1}$. Since MAXI can measure the spectrum (temperature and emission measure), we can estimate the size of the plasma and the magnetic fields. The size sometimes exceeds the size of the star. The magnetic field is in the range of 10-100 gauss, which is a typical value for solar flares.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.3
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• pp.199-206
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• 2013

Electrowinning process in pyroprocessing recovers U (uranium) and TRU (Trans Uranium) elements simultaneously from spent fuels using a liquid cadmium cathode (LCC). When the solubility limit of U deposits over 2.35wt% in Cd, U dendrites were formed on the LCC surface during the electrodeposition at $500^{\circ}C$. Due to the high surface area of dendritic U, the deposits were not submerged into the liquid cadmium pool but grow out of the LCC crucible. Since the U dendrites act as a solid cathode, it prevents the co-deposition of U and TRUs. In this study, the electrodeposition of U onto a LCC was carried out at 440 and $500^{\circ}C$ to compare the morphology and component of U deposits. The U deposits at $440^{\circ}C$ have a specific shape and were stacked regularly at the center of the LCC pool, while the U dendrites (i.e., ${\alpha}$-phase) at $500^{\circ}C$ were grow out of the LCC crucible. Through the microscopic observation and XRD analysis, the electrodeposits at $440^{\circ}C$, which have a round shape, were identified as an intermetallic compound such as $UCd_{11}$. It can be concluded that the LCC electrowinning operation at $440^{\circ}C$ achieves the co-recovery of U and TRU without the formation of U dendrites.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.261-270
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• 2018

In this study, to replace the 'J-slot joint', a joint device between a disposal canister and an emplacement jig in Deep Borehole Disposal process, a novel joint device was designed and tested. The novel joint device was composed of a wedge on top of a disposal canister and a hook box at the end of a winch system. The designed joint device had merits in that it can recombine an emplaced canister freely without the replacement of the joint component. Moreover, it can be applied to various emplacement jigs such as drill pipes, wire-lines, and coiled tubing. To demonstrate the designed joint device, the joint device (${\Phi}110mm$, H 148 mm), a twin canister string (${\Phi}140mm$, H 1,105 mm), and a water tube (${\Phi}150mm$, H 1,500 mm) as a borehole model were manufactured at 1/3 scale. As deployment muds, Na-type bentonite (MX-80) and Ca-type (GJ II) bentonite muds were prepared at solid contents of 7wt% and 28wt%, respectively. The manufactured joint device showed good performance in pure water and viscous muds, with an operation speed of $10m{\cdot}min^{-1}$. It was concluded that the newly developed joint device can be used for the emplacement and retrieval of a deep disposal canister, below 3~5 km, in the future.

• Journal of Biomedical and Translational Research
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• v.19 no.4
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• pp.116-124
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• 2018

Korean Native Pig (KNP) has a uniform black coat color, excellent meat quality, white colored fat, solid fat structure and good marbling. However, its growth performance is low, while the western origin Yorkshire pig has high growth performance. To take advantage of the unique performance of the two pig breeds, we raised crossbreeds (KNP ${\times}$ Yorkshire to make use of the heterotic effect. We then analyzed the liver transcriptome as it plays an important role in fat metabolism. We sampled at two stages: 10 weeks and at 26 weeks. The stages were chosen to correspond to the change in feeding system. A total of 16 pigs (8 from each stage) were sampled and RNA sequencing was performed. The reads were mapped to the reference genome and differential expression analysis was performed with edgeR package. A total of 324 genes were found to be significantly differentially expressed (${\left|log2FC\right|}$ > 1 & q < 0.01), out of which 180 genes were up-regulated and 144 genes were down-regulated. Principal Component Analysis (PCA) showed that the samples clustered according to stages. Functional annotation of significant DEGs (differentially expressed genes) showed that GO terms such as DNA replication, cell division, protein phosphorylation, regulation of signal transduction by p53 class mediator, ribosome, focal adhesion, DNA helicase activity, protein kinase activity etc. were enriched. KEGG pathway analysis showed that the DEGs functioned in cell cycle, Ras signaling pathway, p53 signaling pathway, MAPK signaling pathway etc. Twenty-nine transcripts were also part of the DEGs, these were predominantly Cys2His2-like fold group (C2H2) family of zinc fingers. A protein-protein interaction (PPI) network analysis showed that there were three highly interconnected clusters, suggesting an enrichment of genes with similar biological function. This study presents the first report of liver tissue specific gene regulation in a cross-bred Korean pig.

• FLOWER RESEARCH JOURNAL
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• v.18 no.3
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• pp.179-185
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• 2010

This study was carried out to investigate the optimal culture conditions for gametophytes growth and sporophytes regeneration of Pyrrosia linearifolia in order to provide for the masspropagation system foundation of Pyrrosia linearifolia using their life cycle. Among many different media, 2MS medium was most effective in prothallus proliferation. Prothallus growth was promoted as the total concentration of nitrogen sources increased, and the best result was observed on 120 mM nitrogen. The best concentration of sucrose was 3%. The addition of 5~20 mM IAA, NAA, BA and kinetin promoted the propagation of prothallus. But 2iP demonstrated the most inhibitory effect on prothallus proliferation. Gametophytes shaking-cultured with liquid medium showed similar growth with solid medium and normal formation of reproductive organs. Shoot regeneration was most effective on 1/8MS medium, but growth was promoted on 1/2MS medium. For promotion of shoot regeneration and growth, the suitable concentrations of sucrose and $NaH_2PO_4$ were 1% and $50{\sim}100mg{\cdot}mL^{-1}$ in 1/8MS medium, respectively.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.819-825
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• 2018

Porous nanofibers comprising hollow ${\alpha}-Fe_2O_3$ nanospheres were prepared by applying both template method and Kirkendall diffusion effect to electrospinning process. During heat-treatment processes, the solid Fe nano-metals formed by initial heat-treatment in the carbon matrix were converted into the hollow structured ${\alpha}-Fe_2O_3$ nanospheres. In particular, PS nanobeads added in the spinning solution were decomposed and formed numerous channels in the composite, which served as a good pathway for Kirkendall diffusion gas. The resulting porous nanofibers comprising hollow ${\alpha}-Fe_2O_3$ nanospheres were applied as an anode material for lithium-ion batteries. The discharge capacities of the nanofibers for the 30th cycle at a high current density of $1.0A\;g^{-1}$ was $776mA\;h\;g^{-1}$. The good lithium ion storage property was attributed to the synergetic effects of the hollow ${\alpha}-Fe_2O_3$ nanospheres and the interstitial nanovoids between the nanospheres. The synthetic method proposed in this study could be applied to the preparation of porous nanofibers comprising hollow nanospheres with various composition for various applications, including energy storage.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.109-115
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• 2019

In arc-welding applying to the present automobile part manufacturing process, a wrist-hollow type arc welding robot can shorten the welding cycle time, because feedability of a welding wire is not affected by a robot posture and thus facilitates high-quality arc welding, based on stable feeding with no entanglement. In this paper, we will propose the optimization of wrist design for a wrist-hollow type 6-Axis articulated robot. Specifically, we will perform the investigation on the optimized design of inner diameter of hollow arms (Axis 4 and Axis 6) and width of the upper arm by using the simulation of robot motion characteristics, using a Genetic Algorithm (i.e., GA). Our simulations are based on $SolidWorks^{(R)}$ for robot modeling, $MATLAB^{(R)}$ for GA optimization, and $RecurDyn^{(R)}$ for analyzing dynamic characteristics of a robot. Especially $RecurDyn^{(R)}$ is incorporated in the GA module of $MATLAB^{(R)}$ for the optimization process. The results of the simulations will be verified by using $RecurDyn^{(R)}$ to show that the driving torque of each axis of the writs-hollow 6-axis robot with the optimized wrist design should be smaller than the rated output torque of each joint servomotor. Our paper will be a guide for improving the wrist-hollow design by optimizing the wrist shape at a detail design stage when the driving torque of each joint for the wrist-hollow 6-axis robot (to being developed) is not matched with the servomotor specifications.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.42-48
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• 2021

Zn and Al added LiNi0.85Co0.15O2 cathode materials were synthesized to improve electrochemical properties and thermal stability using a solid-state route. Crystal structure, particle size and surface shape of the synthesized cathode materials was measured using XRD (X-ray diffraction) and SEM (scanning electron microscopy). CV (cyclic voltammetry), first charge-discharge profiles, rate capability, and cycle life were measured using battery cycler (Maccor, series 4000). Strong binding energy of Al-O bond enhanced structure stability of cathode material. Electrochemical properties were improved by preventing cation mixing between Li+ and Ni2+. Large ion radius of Zn+ increased lattice parameter of NC cathode material, which meant unit-cell volume was expanded. NCZA25 showed 80% of capacity retention at 0.5 C-rate during 100 cycles, which was 12% higher than that of NC cathode. The discharge capacity of NCZA25 showed 104 mAh/g at 5 C-rate. NCZA25 achieved 36 mAh/g more capacity than that of NC cathod. NCZA25 cathode material showed excellent rate capability and cycling performance.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.77-92
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• 2021

The energy density of lithium-ion batteries (LIBs) determines the mileage of electric vehicles. For increasing the energy density of LIBs, it is necessary to develop high-capacity active materials that can store more lithium ions within constrained weight. The rapid progress made in cathode technology has realized the utilization of the near-theoretical capacity of cathode materials. In contrast, commercial LIBs have still exploited graphite as active material in anodes since the 1990s. The most promising way to increase anodes' capacity is to mix high-capacity and long-cycle-life silicon oxides (SiOx) with graphite. However, the low initial Coulombic efficiency (ICE) of SiOx limits its content below 15 wt%, impeding the capacity increase in anodes. To address this issue, various prelithiation techniques have been proposed, which can improve the ICE of high-capacity anode materials. In this review paper, we introduce the principles and expected effects of prelithiation techniques reported so far. According to the reaction mechanisms, the strategies are categorized. Mainly, we focus on the recent progress of solution-based chemical prelithiation methods with commercial viability, of which lithiation reaction occurs homogeneously at liquid-solid interfaces. We believe that developing a cost-effective and mass-scalable prelithiation process holds the key to dominating the anode market for next-generation LIBs.