• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.1
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• pp.26-32
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• 2012

This paper presents a metamaterial absorber unit sell structure with four-element electric-LC resonators (ELC). In order to enhance the operating bandwidth of the proposed absorber unit cell two pairs of ELC resonators with a different size are used. The proposed unit cell shows negative permittivity and permeability when the electric field is parallel to the capacitive gap and the magnetic field is normal to the plane of ELC resonator. The simulated results show peak absorbance over 90% at two frequencies of 8.53 and 9.08 GHz, respectively.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.628-631
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• 2003

The recombinant alanine dehydrogenase (ADH) from E. coli containing Thermus caldophilus ADH was purified to homogeneity from a cell-free extract. The enzyme was purified 38-fold with a yield of 68% from the starting cell-free extract. The purified enzyme gave a single band in polyacrylamide gel electrophoresis, and its molecular weight was estimated to be 45 kDa. The pH optimum was 8.0 for reductive amination of pyruvate and 12.0 for oxidative deamination of L-alanine. The enzyme was stable up to $70^{\circ}C$. The activity of the enzyme was inhibited by 1 mM $Zn^{2+}$, 20% hexane, and 20% $CHCl_3$. However, 10 mM $Mg^{2+}$ and 40% propanol had no effect on the enzyme activity. The Michaelis constants ($K_m$) for the substrates were $50\;\mu\textrm{M}$ for NADH, 0.2 mM for pyruvate, 39.4 mM for $NH_4+$, 2.6 mM for L-alanine, and 1.8 mM for $NAD^+$.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.3
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• pp.133-143
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• 2016

The objective in here is to find the density, stiffness, and strength of truss-wall rectangular (TWR) model which is combined with lattice truss (MLT) inside space. The TWR unit-cell model is defined as a unit cell originated from a solid-wall rectangular (SWR) model and it has an empty space inside. Thus, the empty space inside of the TWR is filled with lattice truss model defined as TWR-MLT. The ideal solutions derived of TWR-MLT are based on TWR with MLT model and it has developed by Gibson-Ashby's theory. To validate the ideal solutions of the TWR-MLT, ABAQUS software is applied to predict the density, strength, and stiffness, and then each of them are compared with the Gibson-Ashby's ideal solution as a log-log scale. Applied material property is stainless steel 304 because of cost effectiveness and easy to get around. For the analysis, SWR and TWR-MLT models are 1mm, 2mm, and 3mm truss diameter separately within a fixed 20mm opening width. In conclusion, the relative Young's modulus and relative yield strength of the TWR-MLT unit model is reasonably matched to the ideal expectations of the Gibson-Ashby's theory. In nearby future, TWR-MLT model can be verified by advanced technologies such as 3D printing skills.t.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.657-661
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• 2008

Recently, products of electronic industry and related parts are required to have the thickness thinner and thinner to reduce the part weight. To go with this trend, LGP(light guide plate) of LCD-BLU(Liquid Crystal Display-Back Light Unit: It is one of kernel parts of LCD) for cell phone has the thickness of ${\sim}0.3mm$ and the battery case of cell phone has ${\sim}0.25mm$. Accordingly, high speed injection molding is required to mold products which have thinner parts. To achieve high speed injection and proper control of hydraulic unit, various design was applied to conventional injection unit. In the present paper, we concentrated on the molding stability of hydro-mechanical high speed injection machine to make an LGP of 0.3mm thickness.

• Membrane Journal
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• v.2 no.2
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• pp.122-128
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• 1992

A study on the citric acid production was performed in various size dual hollow fiber bioreactors with immobilized Aspergillus niger (KCTC 1232). The final dry cell mass density reached 300g/l based on the space volume available for cell growth. Under air and oxygen aeration the volumethe productivity reached 0.63 and 1.02g/l.h, which cormsponded to 10 and 16 fold over those of batch fermentation, respectively. The initial pH of the medium was a critical factor and the lower value resulted in higher citric acid yield. The increase in the feeding rate of medium or the number of reactor unit resulted in the improvement of the productivity due to higher consumption rate of substrate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6C
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• pp.594-600
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• 2002

A data manipulation unit capable of bit partitioned shift and various multimedia data type conversions in addition to conventional shift, is presented. Utilizing the similarity between the data type conversion and the shift, the addition of small amount of interconnections to conventional barrel shifter enables data type conversion as well as shift operations with minimal hardware overhead. The presented data manipulation unit is composed of the shifter block for conventional shift and a pack and a unpack block. It has been designed with verilog HDL and the VLSI implementation results using compass 0.6 um standard cell are discussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.840-843
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• 2012

In this paper, the authors present a new design for a dual-band metamaterial(MTM) absorber that utilizes resonant-magnetic inclusion of a split-ring resonator(SRR). The proposed MTM unit cell is constructed by two open complementary split-ring resonators(OCSRRs) and an SRR arrangement. To avoid the need for metallic back plate a planar array of SRRs for resonant-magnetic inclusion is placed facing toward the incident wave propagation direction. Each unit cell is printed on the two sides of a FR-4 substrate. A prototype absorber was fabricated with a planar array of $39{\times}39$ unit cells, and measured. The proposed backplane-less absorber can be used for microwave applications.

• Journal of Ginseng Research
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• v.45 no.5
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• pp.599-609
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• 2021

Ginseng has long been considered as an herbal medicine. Recent data suggest that ginseng has antiinflammatory properties and can improve learning- and memory-related function in the central nervous system (CNS) following the development of CNS neuroinflammatory diseases such as Alzheimer's disease, cerebral ischemia, and other neurological disorders. In this review, we discuss the role of ginseng in the neurovascular unit, which is composed of endothelial cells surrounded by astrocytes, pericytes, microglia, neural stem cells, oligodendrocytes, and neurons, especially their blood-brain barrier maintenance, anti-inflammatory effects and regenerative functions. In addition, cell-cell communication enhanced by ginseng may be attributed to regeneration via induction of neurogenesis and angiogenesis in CNS diseases. Thus, ginseng may have therapeutic potential to exert cognitive improvement in neuroinflammatory diseases such as stroke, traumatic brain injury, multiple sclerosis, Parkinson's disease, and Alzheimer's disease.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.258-262
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• 1993

Two single crystals of fully dehydrated $Rb^+$ -exchanged zeolite A have been prepared by the reduction of all $Ca^{2+}$ ions in dehydrated $Ca_6$-A by rubidium vapor. Their structures were determined by single crystal X-ray diffraction methods in the cubic space group Pm3m (a=12.160(2) $^{\AA}$ and 12.166(2) $^{\AA}$) at 22(1)$^{\circ}$C. In these structures, 12.4(2) to 13.3(2) Rb species are found per unit cell, more than 12 Rb$^+$ ions needed to balance the anionic charge of the zeolite framework, indicating that the sorption $Rb^0$ has occurred. In each structure, three $Rb^+$ ions per unit cell are located at the centers of the 8-rings. Six to eight $Rb^+$ ions are found opposite the 6-rings on threefold axes, and three $Rb^+$ ions are found in a sodalite unit. About 0.5 $Rb^+$ ion lies opposite a 4-ring. The structural analysis indicates the presence of a triangular rubidium cluster in the sodalite cavities. The triangular rubidium clusters may be stabilized by the coordination to two and/or three rubidium ions in the large cavity. Therefore, this cluster may be viewed as $(Rb_5)^{4+}$ and/or $(Rb_6)^{4+}$.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.15-21
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• 2011

In this paper, an energy management circuit for solar energy harvesting system is designed in $0.35{\mu}m$ CMOS technology. The solar energy management system consists of an ISC(Integrated Solar Cell), a voltage booster, and an MPPT(Maximum Power Point Tracker) control unit. The ISC generates an open circuit voltage of 0.5V and a short circuit current of $15{\mu}A$. The voltage booster provides the following circuit with a supply voltage about 1.5V. The MPPT control unit turns on the pMOS switch to provide the load with power while the ISC operates at MPP. The SEMU(Solar Energy Management Unit) area is $360{\mu}m{\times}490{\mu}m$ including pads. The ISC area is $500{\mu}m{\times}2000{\mu}m$. Experimental results show that the designed SEMU performs proper MPPT control for solar energy harvested from the ISC. The measured MPP voltage range is about 370mV∼420mV.