• Bulletin of the Korean Chemical Society
• /
• v.25 no.4
• /
• pp.539-544
• /
• 2004

The ability of protoberberine alkaloids, berberine and berberrubine, to act as topoisomerase II poisons is linked to the anti-cancer activity. Minor alterations in structure have a significant effect on their relative activity. Berberine, which has methoxy group at the 19-position, is significantly less potent than berberrubine. Several observations support non-specific binding to HP14 by the berberine: (i) nonspecific upfield changes in $^1H$ chemical shift for protons of the berberine; (ii) the broadening of imino protons of HP14 upon binding of the berberine; (iii) very small increases in duplex melting temperature in the presence of the berberine. Our results reveal that substitution of a hydroxyl group to a methoxy group on the 19-position, thereby converting the berberrubine to the berberine is associated with a non-specific DNA binding affinity and a reduced topoisomerase II poisoning. The presence of a bulky 19-methoxy substituent decreases intercalating properties of berberine and makes it inactive as topoisomerase II poison.

• Journal of Magnetics
• /
• v.21 no.3
• /
• pp.348-355
• /
• 2016

Precision motion stages used in the manufacturing process of flat-panel displays have inevitably low settling performance due to their huge mass and bulky structures. In order to improve the settling performance, several methods of frame vibration compensation have been developed so far. These methods are used to cancel the vibration by imposing a counter force or modifying the resonance mode of the frame of the stage. To compensate the frame vibration, high force actuators are required. In this paper, a mighty voice coil actuator is proposed to generate the counter force against the frame vibration. The proposed voice coil actuator has an axis-symmetric rectangular structure to achieve a large force with simple and low cost fabrication. Also, the voice coil actuator allows radial clearance up to ${\pm}4mm$. Using an optimized design process and a magnetic circuit model, the power consumption is minimized while the required force is obtained. With a power of 322 W, the VCA has been designed to have a maximum force of 574 N with a force constant of 164 N/A. Experimental results verified the force constant of the fabricated voice coil actuator is well matched with the designed value.

• Korean Journal of Materials Research
• /
• v.3 no.4
• /
• pp.344-351
• /
• 1993

The crystal structunes of poly(ethylene terephthalate-eo-1, 4 cyciohexylene dimethylene terephthalate), P(ET CT), copolymers were studied by CPMAS solid state NMR spectroscopy. With the estimation of methylene resonance peaks, the bulkier CT component of the copolymer in the range of 0 20 mol% CT is excluded from the ET crystal lattice, whereas smaller ET component of the copolymer in the range of 66 100 mol% CT can be partially included into the CT crystal lattice. Those different crystallization behavior can be explained with the difference in chain bulkiness and crystal lattice dimension be tween two copolymer compurwnts.

• Macromolecular Research
• /
• v.11 no.6
• /
• pp.471-475
• /
• 2003

A new poly[2-(2',5'-dimethylphenyl)-1,4-phenylenevinylene] (PDMPPV) that features a bulky 2',5'-dimethylphenyl substituent, which can induce steric hindrance between the PPV backbone and the methyl groups, was designed and synthesized. The polymer structure having no TBB defects was confirmed by $^1$H-NMR and $\^$13/CNMR spectroscopy. The polymer showed good thermal stability with high T$\_$g/. The polymer film showed a maximum absorption at 415 nm with an absorption onset at 480 nm. The maximum emission peak showed at ca. 515 nm, with a shoulder at 530 nm. The turn-on voltages of ITO/PEDOT/PDMPPV/Al and ITO/PDMPPV/Al devices were 8 and 10 V, respectively. The electroluminescence spectrum from the device showed a maximum peak at 510 nm with a shoulder at ca. 535 nm.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.34 no.10
• /
• pp.1581-1595
• /
• 2010

This paper investigates the regional characteristics of street fashion in China. Yanji, Beijing, Shanghai were chosen as three different cities in terms of location, weather, population, and industrial structure. A total of 592 pictures were collected through an internet and fashion magazine search for street fashion in Beijing and Shanghai in addition photos were taken for those in Yanji. Pictures of each city were classified into groups based on overall images covering top, bottom, and accessories to identify the characteristics of style in each group. The classification process included 2 stages. In the first stage, it produced 2 groups: formal and casual. The second stage divided formal into business formal and retro formal; casual was divided into II sub-groups that were easy, sporty, feminine, sexy, ethnic, girlish, nippon, trendy, bulky, military, and mixed. Easy casual showed the highest frequency for 3 cities and military style showed the lowest. Shanghai showed higher frequency in sporty, trendy, and military style than other cities. Each style exposed the similarities and differences in the cities that reflected different regional characteristics.

• Journal of the Korean Applied Science and Technology
• /
• v.16 no.2
• /
• pp.127-133
• /
• 1999

New electroluminescent materials base on anthracene chromophore, [9.10-bis(${\alpha}$-naph -thylethenyl) anthracene (${\alpha}$-BNA)] were newly synthesized. The anthracene derivatives with bulky substituent possessed high melting point and they gave stable amorphous films through vacuum - sublimation methods. Three types of electroluminescent devices were fabricated with double layer and triple layer structure : ITO/TPD/emission layer/MgAg, ITO/emission layer/ OXD-7 and ITO/ TPD/ emission layer/OXD-7/MgAg, respectively. In three types of devices with the emissive layer of ${\alpha}$-BNA, efficient orange electroluminescence was observed. In the triple layer device whit a emitting layer of 20 nm thickness , maximum luminance was about 10000 cd/ $m^2$ at an applied voltage of 10v and maximum external quantum efficiency was 1.0%.

• Journal of the Optical Society of Korea
• /
• v.15 no.3
• /
• pp.216-221
• /
• 2011

A diffraction grating is a highly symmetric optical element with a physical structure that is invariant under translational spatial movements. The translational symmetry is reflected in the fields that are diffracted from the grating. Here, we introduce a plane-parallel mirror pair onto the grating, which translates the fields through double reflections, and we describe a method of exploiting the symmetry to enhance the spectral resolution of a diffraction grating beyond the limit that is set by the number of grooves. The mirror pair creates another virtual grating beside the original one, effectively doubling the number of grooves. Addition of more mirror pairs can further increase the effective number of grooves despite the increased complexity and difficulty of experimental implementation. We experimentally demonstrate the spectral linewidth reduction by a factor of four in a neon fluorescence spectrum. Even though the geometrical restriction on the mirror deployment limits our method to a certain range of the whole spectrum, as a practical application example, a bulky spectrometer that is nearly empty inside can be made compact without sacrificing the resolution.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1997.10a
• /
• pp.39-45
• /
• 1997

Introduction : Polyimides are one of the most important classes of the high performance polymers due to their excellent electrical, thermal, and high-temperature mechanical properties. But their uses are limited because of their poor solubility. Most polyimide derivatives are processed in the form of polyamic acids, which are subsequently converted into the imide structures.Recently, it has been found that the soluble polyimides with large molecular weight sufficient to application. For enhancing processability, the majority of approaches have involved the following factors. As much as, the separation of the imide ring along the back-bone, that is to say, reducing the density of imide ring in the repeat structure. The introduction of bulky substituents along the back-bone, in order to enhance the free volume of main-chain. The incorporation of flexible or thermally stable linkages in the main-chain, reducing the packing force. The disruption of symmetry or recurrence regularity through copolymerization in order to reduce crystallnity.The objectives of this investigation are the synthesis and characterization of soluble polyimides as membrane materials by the single-step polymerization and the preparation of the asymmetric polyimide membrane by using phase inversion technique. In the present study, three series of polyimide derivatives are synthesized; H series is homopolyimides, A series is prepared from single dianhydride and two diamines, B series is yielded from two dianhydrides and a diamine. The dope solution was directly prepared from the PI solution via one step polymerization from monomers.

• Journal of Institute of Control, Robotics and Systems
• /
• v.22 no.7
• /
• pp.513-518
• /
• 2016

The piezoelectric actuating device is known for its large power density and simple structure. It can generate a larger force than a conventional actuator and has also wide bandwidth with fast response in a compact size. To control the piezoelectric actuator, we need an analog signal conditioning circuit as well as digital microcontrollers. Conventional microcontrollers are not equipped with an analog part and need digital-to-analog converters, which makes the system bulky compared with the small size of piezoelectric devices. To overcome these weaknesses, we are developing a single-chip controller that can handle analog and digital signals simultaneously using mixed-signal FPGA technology. This gives more flexibility than traditional fixed-function microcontrollers, and the control speed can be increased greatly due to the parallel processing characteristics of the FPGA. In this paper, we developed a floating-point multiplier, PWM generator, 80-kHz power control loop, and 1-kHz position feedback control loop using a single mixed-signal FPGA. It takes only 50 ns for single floating-point multiplication. The PWM generator gives two outputs to control the charging and discharging of the high-voltage output capacitor. Through experimentation and simulation, it is demonstrated that the designed control loops work properly in a real environment.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.45 no.1
• /
• pp.25-30
• /
• 2008

In this study, the Fourier-Domain optical measurement system, which use a commercial high power white LED as a light source and a CCD linear-array as a detector is realized. The proposed system shows the axial measurement range over $125{\mu}m$ and the axial resolution below $1.24{\mu}m$. This system has the advantage of the cost effective and compact structure and also the better resolution than the existing technologies, which have a resolution above a few of ${\mu}m$ and use bulky and/or expensive broadband light sources.