• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.135-141
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• 2009

For more reliable estimation of soil-structure interaction and seismic source and attenuation properties, site amplification function should be considered. This study use the Nakamura's method (1989) for estimating site amplification though various methods for the same purpose have been proposed. This method was originally applied to the surface waves of background noise and therefore there are some limitation for applications to general wave energy. However, recently this method has been extended and applied to the S wave energy successfully. This study applied the method to the coda wave energy which is equivalent to the backscattered S wave energy. We used more than 60 observed ground motions from 5 earthquakes which occurred recently, with magnitude range from 3.6 to 5.1 Each station showed characteristic site amplification property in low-, high- and resonance frequency ranges. In the case of comparing these results to those from S wave energy, lots of information to the site classification work can be gained. Moreover, removal of site amplification can give us more reliable seismic source parameters.

• Journal of Power Electronics
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• v.14 no.5
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• pp.1047-1056
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• 2014

In most grid-connected inverters (GCI) with an LCL filter, since the design of both the LCL filter and the controller is done separately, considerable tuning efforts have to be exerted when compared to inverters using an L filter. Consequently, an integrated co-design of the filter and the controller for an LCL-type GCI is proposed in this paper. The control strategy includes only a PI current controller and a proportional grid voltage feed-forward controller. The capacitor is removed from the LCL filer and the design procedure starts from an L-type GCI with a PI current controller. After the PI controller has been settled, the capacitor is added back to the filter. Hence, it introduces a resonance frequency, which is identified based on the crossover frequencies to accommodate the preset PI controller. Using the proposed co-design method, harmonic standards are satisfied and other practical constraints are met. Furthermore, the grid voltage feed-forward control can bring an inherent damping characteristic. In such a way, the good control performance offered by the original L-type GCI and the sharp harmonic attenuation offered by the latter designed LCL filter can be well integrated. Moreover, only the grid current and grid voltage are sensed. Simulation and experimental results verify the feasibility of the proposed design methodology.

• Journal of Microbiology
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• v.45 no.3
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• pp.187-192
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• 2007

REOviruses (Respiratory Enteric Orphan viruses) are ubiquitous, non-enveloped viruses containing 10 segments of double-stranded RNA (dsRNA) as their genome. They are common isolates of the respiratory and gastrointestinal tract of humans but are not associated with severe disease and are therefore considered relatively benign. An intriguing characteristic of reovirus is its innate oncolytic potential, which is linked to the transformed state of the cell. When immortalized cells are transfected in vitro with activated oncogenes such as Ras, Sos, v-erbB, or c-myc, they became susceptible to reovirus infection and subsequent cellular lysis, indicating that oncogene signaling pathways are exploited by reovirus. This observation has led to the use of the virus in clinical trials as an anti-cancer agent against oncogenic tumors. In addition to the exploitation of oncogene signaling, reovirus may further utilize host immune responses to enhance its antitumor activity in vivo due to its innate interferon induction ability. Reovirus is, however, not entirely benign to immunocompromised animal models. Reovirus causes so-called "black feet syndrome" in immunodeficient mice and can also harm neonatal animals. Because cancer patients often undergo immunosuppression due to heavy chemo/radiation-treatments or advanced tumor progression, this pathogenic response may be a hurdle in virus-based anticancer therapies. However, a genetically attenuated reovirus variant derived from persistent reovirus infection of cells in vitro is able to exert potent anti-tumor activity with significantly reduced viral pathogenesis in immunocompromised animals. Importantly, in this instance the attenuated, reovirus maintains its oncolytic potential while significantly reducing viral pathogenesis in vivo.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1229-1234
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• 2018

In this paper, a fire prevention system based on a broadband powerline communication (PLC) system is implemented and a demonstration experiment is carried out to prevent from or promptly dealing with possible fires within the nacelle of a wind turbine generator system (WTGS). For this purpose, an inductive coupler having satisfactory attenuation characteristic in the frequency region for high-speed PLC is also manufactured. It is confirmed that the implemented system can monitor the environmental change inside the nacelle in real time by transmitting various information obtained by the sensors such as temperature, flame, and smoke sensor installed in the nacelle and thermal image recorded by a thermal camera to the ground control center through the PLC system. Therefore, it is, considered that the implemented system will significantly improve the reliability of the fire monitoring and prevention system of the WTGS in conjunction with the existing safety system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.66-69
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• 2016

In this paper, we suggests a Ka-band LNB considering next-generation UHD satellite TVRO. Since Ka-band has grater attenuation than Ku-band in atmosphere, we designed the low-noise down-converter to improve receiving sensitivity and to extend a dynamic range of receiver. It aims to compensate a quality of ultra high definition transmission signal for rainfall. The low-noise block diagram consists of a three-staged amplifier (LNA), band-pass filter for deleting image (BPF), mixer and IF when considering nonlinear characteristics in the receiver RF front end module. Also, we showed a LNB through optimization processes affecting dynamic range directly in receiver FEM. Asa resuly of experiment, the gain of low-noise down-converter show between 58.5dB and 60.7dB, the noise figure has a high characteristic as 1.38dB. Finally, the phase noise of local oscillator is -63.10dBc at 100MHz offset frequency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.2
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• pp.136-141
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• 2021

Heating cables, widely used in office buildings, factories, streets and railways, deteriorate in electrical insulation during operation. The insulation deterioration of heating cables leads to electric discharges that can cause electrical fires. With this background, this paper dealt with a condition monitoring technique for heating cables by the analysis of discharge signals to prevent electrical fires. Insulation deterioration was simulated using an arc generator specified in UL1699 under AC operation, and the characteristic and propagation of discharge signals were analyzed on a 100 meter-long heating cable. Discharge signals produced by insulation deterioration were detected as a voltage pulse because they are as small as a few mV and they are attenuated through propagation path. The frequency spectrum of discharge signals mainly existed in the range from 70 kHz to 110 kHz, and the maximum attenuation of the signal was 84.8% at 100 meters away from the discharge point. Based on the experimental results, a monitoring device, which is composed of a high pass filter with the cut-off frequency of 70 kHz, a comparator, a wave shaper and a microprocessor, was designed and fabricated. Also, an algorithm was designed to discriminate the discharge signal in the presence of noise, compared with the pulse repetition period and the number of pulse counts per 100ms. In the experiment, the result showed that the prototype monitoring device could detect and discriminate the discharge signals produced at every discharge point on a heating cable.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.79-85
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• 2023

To make normal operation of S-Band PSR(Primary Surveillance Radar) which are in operation near distance, Minimizing the mutual frequency interference was studied in this paper. First, the phenomenon of radar receiver was analyzed when the interference between PSR was occurred. And next, the proper S-Band Bandpass filter(BPF) was chosen to deal with the interference. And inhibition performance of BPF was verified by comparative analysis of Radar's RF reception characteristic before and after of BPF application. There is 6.4~7.7 dB passband attenuation when BPF was applied at Radar receiver. So the PSR probability of detection were compared and analyzed to check the radar detection performance was deteriorated or not, And this result proved the usefulness of this study.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.235-235
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• 2011

Lau basin of south Pacific, as an active back arc basin, is promising area bearing seafloor massive hydrothermal deposit that is located in a subduction zone between the Pacific ocean plate and Indo-Australian continental plate. Korea Ocean Research and Development Institute tracked from 2004 to 2006 the hydrothermal activity to the extension of the northeast Lau Basin, targeting seamount. hydrothermal activity by tracking was found hydrothermal evidences. In this study, Marine seismic survey was carried out in the Lau basin seamount of the possibility of hydrothermal deposit. In particular, Marine magnetic survey and seismic survey was carried out at the same time in TA-12 seamount and noise characteristics were found in the seamount. the main process of data processing is Bandpass filter, FK filter, Deconvolution for noise attenuation such backscatter and multiple reflections. the migration is performed to compensate for reflection points followed by seamount of a slope. In this study, bedrock and upper strata could be identified and in the Future, the comparative method with Multi Beam Echo Sounder(MBES) are likely to derive the correct velocity model, the marine magnetic survey results should be considered.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.486-493
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• 2010

This article introduces a novel ultra wideband(UWB) bandpass filter(BPF) with sharp roll-off characteristics in stripline structure. The UWB characteristic is basically obtained from capacitive coupled cross resonator. The resonator has ${\lambda}/2$ length. And at the center of the resonator, two stubs are loaded, one is a ${\lambda}/8$ short-circuited stub and the other is a ${\lambda}/8$ open-circuited stub. The two stubs provide two attenuation poles at lower and upper cutoff frequencies. For input and output lines, two identical capacitively coupled lines have been installed to suppress the unwanted signals in the lower and upper stopbands. The filter has been designed for the U.S. UWB band(3.1~10.6 GHz) with two transmission zeros at 2.4 and 11.1 GHz. The filter has been realized with Low Temperature Core-fired Ceramic(LTCC) green tape which has the dielectric constant of 7.8. Measurement results agree well with HFSS simulation results. Insertion loss less than 0.7 dB and return loss better than 14 dB in the pass band have been measured. The group delay in the center frequency is 0.27 ns and the group delay variation within pass band is less than 0.5 ns. The size of the filter is $6{\times}18{\times}0.6\;mm^3$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.28-35
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• 2010

In this paper, we designed and fabricated a ultra-wideband(UWB) bandpass filter with a good performance of a stopband, and a notched band in passband. The transformed equivalent circuit of the highpass filter was realized by distributed element. A wide-passband with 3-dB fractional bandwidth of more than 100 % was achieved by using optimum response of the HPF. For improving lower and upper stopband characteristic, a cross coupling between feed lines was employed, which was analyzed by desegmentation technique. In order to reject interference of Wireless LAN and Hyper LAN(5.15~5.825 GHz), the narrow notched(rejection) band was realized by a spurline. The fabricated BPF indicated the passband from 3.1 to 10.55 GHz and the flat group delay of less than 0.94 ns over the entire passband except the rejection band. The filter shown sharp attenuation both inside and outside the band and notched band from 5.2 to 6.12 GHz.