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This paper proposes a lighting system that maintains color temperature of natural light by reflecting the changes of external incoming light. For that, characteristics of indoor lighting environment are measured and experimental environment to control the light is constructed. The color temperature of the natural light by solar terms are derived by analyzing measured natural light database. After that, color temperatures from various points inside the room are measured and LED lighting is controlled by linking it with the measured color temperature data. The results indicated that the lighting system that adaptably reproduce the color temperature of natural light even if external incoming light is changed. The color temperature changes of the indoor lighting environment are measured and analyzed before and after implementing the proposed system to validate the performance of the proposed lighting system that maintains color temperature of natural light.

This paper proposes the reliability improvement of H-Bridge Multi-level (HBM) inverter. This reliability can be implemented through modularization of power circuit, distribution of controller, duplication of controller and communication, and continuous operation method in case of power cell failure for driving medium-voltage & high-power induction motor. It is shown that the modularization and expansion characteristics of the HBM inverter are improved since the individual inverter modules operate more independently when using the proposed concept. Also the fault tolerance is increased by using power cell bypass. The proposed design and control methods are described in detail and the validity of the proposed system is verified experimentally in various industrial fields.

A novel tetrathiafulvalene (TTF)-based main-chain polymer (6TTF-polymer) was successfully synthesized via a condensation polymerization between a newly synthesized dihydroxy TTF derivative and a malonyl chloride, and its chemical structure was characterized by spectroscopic techniques. Molecular weight of the 6TTFpolymer (9,030 g/mol by gel permeation chromatography) was large enough to form the ductile film. The electrochemical and optical properties of the 6TTF-polymer were further estimated by cyclic voltammetry, ultraviolet and photoluminescence spectroscopes. The highest occupied molecular orbital level (EHOMO = �4.79 eV) and band-gap energy (Eg = 1.91 eV) of the 6TTF-polymer suggested that TTF-based polymer could act as a good electron donating material for the optoelectronic applications.

Multi-walled carbon nanotubes (MWCNTs) were embedded into high-density polyethylene (HDPE) to improve the electrical properties of HDPE polymeric switches. The MWCNT surfaces were modified by oxyfluorination to improve their positive temperature coefficient (PTC) and negative temperature coefficient (NTC) behaviors in HDPE polymeric switches. HDPE polymeric switches exhibit poor electron mobility between MWCNT particles when the number of oxygen functional groups is increased by oxyfluorination. Thus, the PTC intensity of HDPE polymeric switches was increased by the destruction of the electrical conductivity network. The oxyfluorination of MWCNTs also leads to weak NTC behavior in the MWCNT-filled HDPE polymeric switches. This result is attributed to the reduction of the mutual attraction between the MWCNT particles at the melting temperature of HDPE, which results from a decrease in the surface free energy of the C–F bond in MWCNT particles.

Invasive infections of Candida albicans are life-threatening clinical conditions affecting immunosuppressed patients. To maintain genome integrity and diversity, C. albicans utilizes DNA repair systems, such as nucleotide excision repair (NER), to escape from attack by macrophages. Rad3 helicase is a component of the TFIIH complex, which plays a role in transcription and the NER pathway. Accumulated evidence of studies from Archaea to humans has revealed that the conserved structure, including an iron-containing domain, is essential in the function of Rad3 helicase activity. However, no study of the Rad3 protein of C. albicans has yet been reported. In the present study, putative C. albicans Rad3 (CaRad3) has been cloned with orf19.7119 of the Candida genome. CaRad3 proteins were over-expressed and purified from E. coli and S. cerevisiae using a Ni-NTA column and a size exclusion column for physicochemical and functional characterization. Through EMR and spectrometric analysis, we have proven that the purified CaRad3 protein has a Fe-S cluster. We also revealed that CaRad3 protein has a helicase activity on a duplex DNA substrate. Furthermore, we showed that the CaRad3 protein purified from yeasts was N-glycosylated, and that this protein complemented the defects in both the NER pathway and transcription. These data suggest that the Rad3 helicase in C. albicans is the product of the orf19.7119 gene.

In this paper, a capacitance estimation scheme for DC-link capacitors for single-phase AC/DC PWM converters is proposed. Under the no-load condition, a controlled AC current (30[㎐]) is injected into the input side, which then causes AC voltage ripples at the DC output side. Or, a controlled AC voltage can be directly injected into the DC output side. By extracting the AC voltage/current and power components on the DC output side using digital filters, the capacitance value can be calculated, where the recursive least squares (RLS) algorithm is used. The proposed methods can be simply implemented with software only and additional hardware is not required. From the experiment results, a high accuracy estimation of capacitances less than 0.85% has been obtained.

This paper proposes an analysis of voltage delay and compensation for current control in H-Bridge Multi-Level (HBML) inverters for a medium voltage motor drive with vector control. It is shown that the expansion and modularization capability of the HBML inverter is improved in case of using Phase-Shifted Pulse Width Modulation (PSPWM) since individual inverter modules operate more independently. But, the PSPWM of HBML has a phase difference between reference voltage and real voltage, which can cause instability in the current regulator at high speed where the ratio of the sampling frequency to the output frequency is insufficient. This instability of the current regulator is removed by adding a proposed method which compensate a phase difference between reference voltage and real voltage. The proposed method is suitable for HBML inverter controlled by PSPWM with low switching frequency and high speed motor drive. The validity of the proposed method is verified experimentally on 6,600[V] 1,400[kW] induction motor fed by an 13-level HBML inverter.

A series of swallow-shaped tetrathiafulvalene (TTF)-based liquid crystal (LC) molecules (a-6TTFn, where 6 represents the number of carbon atoms in the two tails of a-6TTFn and n is the even number of carbon atoms in the alkyl chains attached to the side of the asymmetric TTF mesogen, n = 6−12) was designed and synthesized. One of this series of swallow-shaped asymmetric TTF molecules (abbreviated as a-6TTF12) having 12 carbon atoms in the alkyl chains attached to the side of the asymmetric TTF mesogen served as an example in this study. Major phase transitions and their origins in a-6TTF12 were studied with combined techniques of differential scanning calorimetry (DSC), one-dimensional (1D) wide-angle X-ray diffraction (WAXD) and solid-state carbon-13 (13C) nuclear magnetic resonance (NMR) experiments. a-6TTF12 formed a highly ordered liquid crystalline (ΦLC) phase at higher temperatures and a crystalline (ΦCr) phase at lower temperatures. On the basis of the experimental results, it was found that the hi...

Transportation can cause stress to laboratory animals and alter physiological characteristics that may confound experimental results. The authors investigated stress-related effects of 3-4 h of transportation by truck in two strains of mice (C57BL/6, which are known to be aggressive, and ICR, which are less aggressive). Transported mice had sufficient space and access to water, though temperature in the truck was lower than what is usually recommended. Transportation affected the following parameters in both strains of mice: (i) serum corticosterone concentrations, (ii) expression of the chaperone proteins Hsp70 and Grp78 in various tissues and (iii) concentrations of serological enzymes that are associated with liver disease. These parameters also differed substantially between the two strains of mice.

In this paper, simulation and test results of a low floor Series Hybrid Electric Vehicle running in BUSAN city driving mode are presented. Hyundai Heavy Industries Company and Daewoo Bus Corporation have jointly developed a prototype Series Hybrid Electric Bus (SHEB) to evaluate vehicle performance together with fuel economy as a part of feasibility study on hybrid bus operation. It is found that the fuel efficiency of SHEB is 22% higher than that of a conventional internal combustion engine bus and our GENSET control method is quite effective in maintaining that battery’s State of Charge (SOC) during bus driving.

In this paper, unbalanced three-phase control method is proposed to increase the fault tolerance for H-bridge multilevel inverter under the conditions of faulty power cells. It is possible to generate a balanced three-phase line-to-line voltage by phase-shifting and bypassing faulty power cells with a minimum voltage drop. In this method, the concept of voltage modulation by using offset voltage is applied to an unbalanced three-phase control method. Especially, it is possible to use the maximum output voltage of inverter by adopting the real time unbalanced control method of phase voltage irrespective of the fault location and the number of disabled power cells. Also, the feasibility of the proposed method is proved by the H-bridge multilevel inverter test composed of 7-level.

In this paper, a novel control algorithm for minimizing the operating loss of doubly fed induction generators (DFIG) for variable speed wind turbines is presented. At first, the generator losses are modeled, which consist of the copper loss and the iron losses. Then, a stator d-axis current is derived which minimizes the total generator loss. Based on this current, the stator reactive power level is controlled. The experimental results for a 3 kW DFIG wind turbine simulator show that the amount of power saving approaches to 23% at 5[m/s] wind speed, which is more significant at low wind speed.

Recently, chip based fabrication of curved microstructures, such as microsphere, microfiber and microtube, has attracted much attention owing to their many advantages. In this paper, we have fabricated pH-responsive flexible microfiber using the microfluidic chip and ‘on the fly’ photopolymerization method, and we characterized their mechanical and swelling properties. First, we have measured the swelling properties according to the pH variation. The PDMS based test apparatus was prepared, and we inserted the microfiber and measured the volume transitions. The shrinking and the swelling motions were measured according to the different sized (50, 80, 100µm) fibers to investigate the size effect. The effects of acrylic acid (AA, pH sensitive monomer) concentration were examined also. As the fibers’ diameter increases, the response of volume transition was slow, and higher AA showed larger volume expansion to the application of basic solution. Second, we have measured the elasticity of microfiber according to AA concentration (weight %: 6, 11, and 22). The elasticity at the fiber having less AA concentration was larger, and this indicates that the fiber having lower AA concentration is softer. The advantages of our fabrication method are as follows; 1) the process is simple and cost effective, 2) we can functionalize the fiber and this can be applied to diverse microdevices such as sensors or actuators, 3) the size can be easily altered via the regulation of flow rate. Here, we showed the fibers’ mechanical properties, and we expect that the microfiber can be applied to the fabrication of artificial muscle.

The use of the CAN communication protocol for H-Bridge Multi-Level (HBML) inverters, and localized PWM generation and AVR is proposed in this paper. It is shown that the performance and reliability of conventional distributed controllers for HBML inverters can be improved with less communication hardware requirements, when using the proposed method. It is also shown that the expansion and modularization capability of the HBML inverter is improved since individual inverter modules operate more independently. The proposed hardware is described in detail and the validity of the proposed system is verified experimentally on a 6,600[V] 1,400[kW] induction motor drive.

This paper presents a new synchronization algorithm for grid connection of a doubly fed induction generator (DFIG) in wind generation system. A stator flux-oriented vector control is used for the variable speed DFIG operation. By controlling the generator excitation current the amplitude of the stator EMF is adjusted equal to the amplitude of the grid voltage. To set the generator frequency equal to the grid one, the turbine pitch angle controller accelerates the turbine/generator until it reaches the synchronous speed. A slight difference of stator and grid frequencies may cause the large phase difference between the two voltages. To compensate for this phase difference, a PLL algorithm is used. After the synchronization is achieved, the generator is connected to the grid and is controlled to extract the maximum power. The effectiveness of the proposed synchronization algorithm is verified by simulation results using PSCAD.

A torque ripple reduction technique of direct torque control (DTC) for high power induction motors driven by 3-level inverters with the inverter switching frequency limited around 0.5-l kHz level is presented. It is noted that conventional DTC algorithms to reduce torque ripple are devised for applications with relatively high switching frequency above 2-3 MHz. Such conventional algorithms cannot accomplish satisfactory torque ripple reduction for 3-level inverter systems with lower switching frequency. A new DTC algorithm, especially for low switching frequency inverter system, illustrates relatively reduced torque ripple characteristics all over the operating speed region. Simulation and experimental results show effectiveness of the proposed control algorithm.

Plasma polymerized methyl methaclylate (ppMMA) thin films were prepared with various process conditions such as inductively coupled plasma (ICP) power, substrate bias power, working pressure, substrate heating temperature, substrate position, and monomer flow rate. Thickness, surface morphology, dielectric constant, and leakage current of the ppMMA thin films were investigated for application to organic thin film transistor as gate dielectric. Deposition rate of over 8.6 nm/min, dielectric constant of 3.4, and leakage current density of 8.9 ×10-9 A/cm-2 at electric field of 1 MV/cm were achieved for the ppMMA thin film prepared at the optimized process condition: plasma power of RF 100 W; Ar flow rate of 20 sccm; working pressure of 5 mTorr; substrate temperature of 100 °C; substrate position of 100 mm. The ppMMA thin film was then applied to pentacene based organic thin film transistor (OTFT) device fabrication. The OTFT device with 80 nm thick pentacene semiconductor layer showed field effect mobility of 0.144 cm2 V-1 s-1 and threshold voltage of -1.72 V.

We propose a single polarizer liquid crystal display (LCD) with a fast response that was designed using a polarization-dependent microlens array fabricated by the planarization of a curved lens surface with a liquid crystalline polymer. The single polarizer LCD is operated by the polarization-dependent focusing properties of a microlens consisting of a circular stop-mask and complementary open mask. Fast response can be obtained by the planarized lens surface because distortions associated with applied electric fields and LC alignments observed in conventional curved lenses are eliminated.

The switching speed of a polarization-independent microlens array fabricated with a nematic liquid crystal (NLC) in the configuration of a plano-convex lens is improved by the reactive mesogen (RM) mixed in an alignment layer. Due to the NLC rotating directions predetermined by the polymerized RM, the direct switching from a vertical alignment to a spiral one is obtained without going through a metastable splay state, which gives rise to slow response in the vertically aligned NLC microlens with polarization independence.

a patterning method of liquid crystalline polymer by using electrohydrodynamics. Using this method, the patterned retarder films, applicable to 3-dimensional displays and transflective liquid crystal displays, were simply fabricated without complicated processes.