• Journal of Korea Multimedia Society
• /
• v.14 no.11
• /
• pp.1431-1437
• /
• 2011

This paper proposes a novel watermarking algorithm that protects digital copyrights and is robust to attacks. Watermarks are embedded in the subband including the significant part of the signal such as a pitch. Generally, the subband containing the pitch has the biggest energy. In order to find this subband, wavelet packet transform is used to decompose the subbands and their energy are calculated. The signal of the selected subbands is transformed in frequency domain using FFT. The watermarks are embedded using QIM for samples higher than a certain threshold. The blind detection uses the Euclidean distance. The proposed method shows less than 5% BER in the audio watermark benchmarking.

• Journal of Power Electronics
• /
• v.18 no.2
• /
• pp.547-557
• /
• 2018

This work proposes a control method of frequency stabilization for grid integration of large-scale wind farms via the voltage source converter-based high-voltage direct current (VSC-HVDC) technology. First, the topology of grid integration of a large-scale wind farm via the VSC-HVDC link is provided, and simple control strategies for wind turbines, wind farm side VSC (WFVSC), and grid side VSC are presented. Second, a mathematical model between the phase angle of WFVSC and the frequency of the wind farm is established. The control principle of the large-scale wind power integrated system is analyzed in theory in accordance with the mathematical model. Third, frequency and AC voltage controllers of WFVSC are designed based on the mathematical model of the relationships between the phase angle of WFVSC and the frequency of the wind farm, and between the modulation index of WFVSC and the voltage of the wind farm. Corresponding controller structures are established by deriving a transfer function, and an optimization method for selecting the parameters of the frequency controller is presented. Finally, a case study is performed under different operating conditions by using the DIgSILENT/PowerFactory software. Results show that the proposed control method has good performance in the frequency stabilization of the large-scale wind power integrated system via the VSC-HVDC technology.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.7
• /
• pp.2939-2946
• /
• 2015

Many of the anti-cancer agents currently used have an origin in natural sources including plants. Aloe vera is one such plant being studied extensively for its diverse health benefits, including cancer prevention. In this study, the cytotoxic potential of Aloe vera crude extract (ACE) alone or in combination with cisplatin in human breast (MCF-7) and cervical (HeLa) cancer cells was studied by cell viability assay, nuclear morphological examination and cell cycle analysis. Effects were correlated with modulation of expression of genes involved in cell cycle regulation, apoptosis and drug metabolism by RT-PCR. Exposure of cells to ACE resulted in considerable loss of cell viability in a dose- and time-dependent fashion, which was found to be mediated by through the apoptotic pathway as evidenced by changes in the nuclear morphology and the distribution of cells in the different phases of the cell cycle. Interestingly, ACE did not have any significant cytotoxicity towards normal cells, thus placing it in the category of safe chemopreventive agent. Further, the effects were correlated with the downregulation of cyclin D1, CYP 1A1, CYP 1A2 and increased expression of bax and p21 in MCF-7 and HeLa cells. In addition, low dose combination of ACE and cisplatin showed a combination index less than 1, indicating synergistic growth inhibition compared to the agents applied individually. In conclusion, these results signify that Aloe vera may be an effective anti-neoplastic agent to inhibit cancer cell growth and increase the therapeutic efficacy of conventional drugs like cispolatin. Thus promoting the development of plant-derived therapeutic agents appears warranted for novel cancer treatment strategies.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.7
• /
• pp.80-91
• /
• 1999

We present various optimal grating structures which give the low threshold gain, good modulation characteristics, small effective linewidth enhancement factor, and large fabrication tolerance in complex-coupled MQW DFB lasers with absorptive gratings. To obtain these, we calculate the complex coupling coefficients using the extended additional layer method and the threshold gain including the modal loss in the absorptive grating region for rectangular and trapezoidal gratings. Based on the comparison of the results for various possible absorptive grating structures, the design guidelines are presented to obtain the low threshold gain or large fabrication tolerance. Among the grating structures studied, the double grating structure consisting of the absorptive grating on the index grating has the largest fabrication tolerance for the threshold gain and the coupling strength. The fabrication tolerance for the coupling ratio is very large for all the grating structures studied.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.6
• /
• pp.472-480
• /
• 2009

This paper describes the overmodulative SVPWM technique and harmonics analyses of three phase NPC type three-level inverter to the modulation index. Three phase NPC type three-level inverter adopted SVPWM to extend the linear region to 0.907, moreover, the following voltage compensation using Fourier series was adopted in the region of overmodulation to make it work to six-step level. PD type of multi carrier method is used with the double Fourier series for the analysis of output power harmonics characteristic. Simulation was performed by PSIM, and the harmonics characteristics of 3-level inverter in each region are analyzed. The side band harmonics of carrier frequency are dominant in the linear region, but these harmonic components are decreased as the inveter goes to overmodulation region, and the harmonics due to the fundamental frequency is increased gradually at the same time. The harmonic analyses are verified through the simulation and experimental results under the same condition.

• Journal of Power Electronics
• /
• v.17 no.1
• /
• pp.56-66
• /
• 2017

Fast and accurate fault detection is the primary step and one of the most important tasks in fault tolerant converters. In this paper, a fast and simple method is proposed to detect and diagnosis the faulty cell in a cascaded H-bridge multilevel inverter under a short circuit fault. In this method, the reference voltage is calculated using switching control pulses and DC-Link voltages. The comparison result of the output voltage and the reference voltage is used in conjunction with active cell pulses to detect the faulty cell. To achieve this goal, the cell which is active when the Fault signal turns to "0" is detected as the faulty cell. Furthermore, consideration of generating the active cell pulses is completely described. Since the main advantage of this method is its simplicity, it can be easily implemented in a programmable digital device. Experimental results obtained with an 11-level inverter prototype confirm the effectiveness of the proposed fault detection technique. In addition, they show that the diagnosis method is unaffected by variations of the modulation index.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.7
• /
• pp.620-624
• /
• 2016

In this paper we designed a current mode logic frequency divider to transmit a baseband amplitude modulated signal. From simulation result, we studied input and output waveforms according to the variation of input bias voltage. For the purpose of the verification of the study, we designed a current mode logic frequency divider at 1,400 MHz. The designed frequency divider operates between 100 MHz and 3,000 MHz, for -33 dBm input power. The circuit draws $I_{total}=30mA$ from $V_{DD}=3V$ supply, and the simulation result shows that an amplitude modulated signal at 1,400 MHz with the modulation index of 0.5 was successfully downconverted to 700 MHz.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.44 no.4 s.316
• /
• pp.109-116
• /
• 2007

Most harmonic synthesis methods using phase information employ a quadratic or cubic phase interpolation. The methods are computationally expensive to implement because every component sinewave must be synthesized on a per sample basis. In this paper, we propose a fast harmonic synthesis method for sinusoidal speech/audio coding based on the quadratic and cubic phase function to overcome the complexity problem. To derive the fast harmonic synthesis method, we define the over-sampling function and phase modulation function by constraining the parameter of phase function to be independent for harmonic index and derive the fast synthesis method using IFFT. Experimental results show that the proposed method significantly reduce the complexity of conventional cosine synthesis method while maintaining the performance.

• Journal of Haehwa Medicine
• /
• v.19 no.2
• /
• pp.85-100
• /
• 2011

In order to investigate the efficacy of HYGBH on atopic dermatitis, various immune related factors were studied. The results and conclusions are as follows. Atopic dermatitis symptoms were improved in HYGBH treated group and significant decrease in dermatitis index were observed in 12 and 14 weeks. HYGBH treated group showed significant decrease in CD4+, CD3+/CD69+ immune cell ratio in PBMC by 18% and 40.6% respectively. HYGBH treated group showed significant decrease in CD3+, CD11b+/Gr-1+ immune cell ratio in dorsal skin by 44.6% and 53.1% respectively. HYGBH treated group showed significant decrease in IL-4, IFN-${\gamma}$ in spleen by 29.5%, 7.7% respectively. HYGBH treated group showed decrease in the expression of IL-5, IL-13, IL-17 and histamine by 21%, 9.6%, 14%, and 32.2% respectively. Also the group showed decrease in the expression of IgE by 6.8% respectively. HYGBH treated group showed significant decrease in the transcription of IL-5 and IL-3 mRNA in skin by 35.5% and 23.2% respectively. The results above indicated that treatment of HYGBH improved atopic dermatitis symptoms by anti-oxidant activity as well as immune modulation activity as a clinical evidence. Also, to increase the application of fermented oriental medicine, different fermentation conditions using various microbial strains should be accumulated as the clinical evidence in the future.

• Journal of Haehwa Medicine
• /
• v.19 no.2
• /
• pp.65-83
• /
• 2011

Various related factors and tissue changes in vitro and in vivo were observed to investigate the efficacy of HYBH on atopic dermatitis. The results are described below. HYBH improved the atopic dermatitis symptoms by naked eye examination, and significantly decreased dermatitis clinical index at 14 weeks. HYBH significantly decreased CD4+/CD45+, CD4+, CD8+, CD3+/CD69+ immune cell ratios in PBMC by 28%, 16%, 30%, 26% and 22% respectively. HYBH significantly decreased CD11b+/Gr-1+, CD3 immune cell ratios in dorsal skin by 35.3% and 67.5% respectively. HYBH significantly decreased the expression of IL-4 and IFN-${\gamma}$ in spleen by 23% and 15% respectively. HYBH significantly decreased the production rate of IL-5, IL-13 and histamine in serum by 17%, 23%, and 8.8% respectively and increased IL-17 production by 17%. HYBH significantly decreased immunoglubulins IgG1 and IgE production in serum. The results above indicated that treatment of HYBH improved atopic dermatitis symptoms by anti-oxidant activity and immune modulation activity as a clinical evidence. Also, different fermentation conditions using various microbial strains should be accumulated as the clinical evidence for broad application in the future.