• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.91-98
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• 2015

There is a new evolution in technological advancement taking place called the Internet of Things (IoT), The IoT enables physical world objects in our surrounding to be connected to the Internet. ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart devices. Accordingly studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi devices using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band. Because serious network performance deterioration of wireless sensor networks. In this paper, we will propose an algorithm that identifies the possibility of using more accurate channels by mixing utilization of interference signal and RSSI (Received Signal Strength Indicator) Min/Max/Activity of Interference signal by wireless sensor nodes. In addition, it will verify our algorithm by using OPNET Network verification simulator.

• Textile Coloration and Finishing
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• v.15 no.4
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• pp.17-23
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• 2003

Fourier transform infrared spectroscopy(FT-IR) was used to characterize the intermolecular ester crosslinkages in cotton cellulose. The FT-IR data show that the band of the ester carbonyl group can be separated from overlapping carboxyl/carbonyl band by converting carboxyl group to carboxylate. When esterification occurs between a polycarboxylic acid and cotton cellulose, the carbonyl groups retained in the cotton exist in three forms; ester, carboxyl, and carboxylate anion. The FT-IR data were also correlated to the durable press rating result obtained. The appearance of BTCA-finished durable press silk/cotton fabrics were improved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.288-297
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• 2007

The novel internal monopole chip antenna of penta-band operation for GSM850/GSM900/DCS/USPCS/WCDMA bands for mobile phones is proposed. This antenna occupies a small volume $8\times3.2\times20mm^3$ and is suitable to be embedded in a mobile phone as an internal antenna. The minimization of the proposed antenna was realized by using spiral line structure and meander line structure on FR-4 of dielectric$(\varepsilon_r=4.4)$. The designed antenna has the wide-band operation in the upper band by overlapping high order resonances. The measured bandwidth of this antenna (VSWR>3) is 150MHz$(1,030\sim1,180\;MHz)$ in the lower band operation and 650 MHz$(1,760\sim2,410\;MHz)$ in higher band operation. The measured radiation efficiency within bandwidth(VSWR 3:1) is over 50 %. The antenna has been designed by a commercial software HFSS.

• Geomechanics and Engineering
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• v.15 no.5
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• pp.1047-1059
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• 2018

This paper focuses on the cracking and fragmentation process in rock materials containing a pair of non-parallel flaws, which are through the specimen thickness, under vertical compression. Several numerical experiments are conducted with varying flaw arrangements that affect the initiation and tensile wing cracks, shear crack growth, and crack coalescing behaviors. To obtain realistic numerical results, a parallelized peridynamics formulation coupled with a finite element method, which is able to capture arbitrarily occurring cracks, is employed. From previous studies, crack initiation and propagation of tensile wing cracks, horsetail cracks, and anti-wing cracks are well understood along with the coalescence between two parallel flaws. In this study, the coalescence behaviors, their fragmentation sequences, and the role of an x-shaped shear band in rock material containing two non-parallel flaws are discussed in detail on the basis of simulation results strongly correlated with previous experimental results. Firstly, crack initiation and propagation of tensile wing cracks and shear cracks between non-parallel flaws are investigated in time-history and then sequential coalescing behavior is analyzed. Secondly, under the effect of varying inclination angles of two non-parallel flaws and overlapping ratios between a pair of non-parallel flaws, the cracking patterns including crack coalescence, fragmentation, and x-shaped shear band are investigated. These numerical results, which are in good agreement with reported physical test results, are expected to provide insightful information of the fracture mechanism of rock with non-parallel flaws.

• The Journal of Korean Physical Therapy
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• v.29 no.1
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• pp.27-32
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• 2017

Purpose: Recent electrophysiological studies have shown that the sensorymotor cortex is activated during both actual action excuted by themselves and observation of action performed by other persons. Observation of action based on mirror neuron system can be used as a cognitive intervention to promote motor learning. The purpose of this study was to investigate the brain activity changes during action observation and action execution using EEG. Methods: Thirty healthy volunteers participated and were requested to perform hand action and to observe the video of hand action performed by another person. The EEG activity was evaluated by a method which segregated the time-locked for each condition. To compare the differences between action observation and execution, the Mu suppression and the relative band power were analysed. Results: The results showed significant mu suppression during the action observation and execution, but the differences between the two conditions were not observed. The relative band power showed a significant difference during the action observation and execution, but there were no differences between the two conditions. Conclusion: These results indicate that action execution and observation involve overlapping neural networks in the sensorymotor cortical areas, proposing positive changes on neurophysiology. We are expected to provide information related to the intervention of cognitive rehabilitation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8C
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• pp.814-821
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• 2009

In an ultrawide band (UWB) indoor wireless localization, time of arrival (TOA) parameter estimation techniques have some difficulties in acquiring a reasonable TOA estimate because of the clustered multipath components overlapping or random time intervals mainly due to non line-of-sight (NLOS) environment. In order to solve that problem and achieve an excellent UWB indoor wireless localization, we propose a UWB signal model and a robust TOA parameter estimation technique that has little effect on the clustered problems unlike the conventional technique. Through simulation studies, the validity of the proposed model and the TOA estimation technique are examined. The performance of estimation error is also analyzed.

• Journal of Astronomy and Space Sciences
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• v.28 no.4
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• pp.299-304
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• 2011

As more satellites are designed to downlink their observed image data through the X-band frequency band, it is inevitable that the occupied bandwidth of a target satellite will overlap with that of other X-band downlink satellites. For sun-synchronized low earth orbit satellites, in particular, it can be expected that two or more satellites be placed within the looking angle of a ground station antenna at the same time. Due to the overlapping in the frequency band, signals transmitted from the adjacent satellites act as interferers, leading to degraded link performance between target satellite and ground station. In this paper, link analysis was initiated by modeling the radiation pattern of ground station antenna through a validated Jet Propulsion Laboratory peak envelope model. From the relative antenna gain depending on the offset angle from center axis of maximum antenna directivity, the ratio of received interference signal level to the target signal level was calculated. As a result, it was found that the degradation increased when the offset angle was within the first point of radiation pattern. For a 7.3 m antenna, serious link degradation began at an offset angle of 0.4 degrees. From this analysis, the link performance of the coming satellite passes can be recognized, which is helpful to establish an operating procedure that will prevent the ground station from receiving corrupted image data in the event of a degraded link.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.109-116
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• 2014

In recent, ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart phone, notebook computer, printer and portable multimedia devices. Accordingly, studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi device using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band causes serious network performance deterioration of wireless sensor networks. This paper examined a method of identifying channel status to avoid interference among wireless communication devices using IEEE 802.11b (Wi-Fi) and other ISM bands during communication among IEEE 802.15.4 based wireless sensor network nodes in ISM band. To identify channels occupied by Wi-Fi traffic, various studies are being conducted that use the RSSI (Received Signal Strength Indicator) value of interference signal obtained through ED (Energy Detection) feature that is one of IEEE 802.15.4 transmitter characteristics. This paper examines an algorithm that identifies the possibility of using more accurate channel by mixing utilization of interference signal and RSSI mean value of interference signal by wireless sensor network nodes. In addition, it verifies such algorithm by using OPNET Network verification simulator.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.187-193
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• 2006

In this paper, we study the coexistence of orthogonal frequency division multiplexing (OFDM)-based systems beyond 3G (B3G) and point-to-point (P-P) fixed service (FS) microwave systems. The advanced general analytical model derived via a power spectral density (PSD) analysis proposed in this paper has two advantages in comparison with the conventional minimum coupling loss (MCL) method. First, the interfering signal power that appears in the band of a victim system can be easily assessed without a spectrum emission mask. Second, when transmit power is not allocated to some subcarriers overlapping the band of the victim system in order to mitigate B3G OFDM-based systems interference with other systems, the general analytical model can successfully assess the interference from the B3G systems into FS systems, whereas the MCL method incorporating the spectrum emission mask cannot be applied in the presence of the same interference condition. The proposed model can be derived in a closed form and is simply implemented with the help of simulation, and thus the solution can be obtained in significantly reduced time. Through application of the proposed model, coexistence results are analyzed in a co-channel and adjacent channel with respect to guard band and minimum separation distance.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3771-3776
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• 2010

The dynamics of the $CN^-$-ligated ferric cytochrome c (CytcCN) in $D_2O$ at 283 K following Q-band photoexcitation at 575 nm was observed using femtosecond time-resolved vibrational spectroscopy. The equilibrium vibrational spectrum of the CN stretching mode of CytcCN shows two overlapping bands: one main band (82%) at $2122\;cm^{-1}$ with $23\;cm^{-1}$ full width at half maximum (fwhm) and the other band (18%) at $2116\;cm^{-1}$ with $7\;cm^{-1}$ fwhm. The time-resolved spectra show bleaching of the CN fundamental mode of CytcCN and two absorption features at lower energies. The bleach signal and both absorption features are all formed within the time resolution of the experiment (< 200 fs) and decay with a life time of 1.9 ps. One transient absorption feature, appearing immediately red to the bleach signal, results from the thermal excitation of low-frequency modes of the heme that anharmonically couple to the CN fundamental mode, thereby shifting the CN mode to lower energies. The shift of the CN mode decays with a lifetime of 2 ps, equivalent to the time scale for vibrational cooling of the low-frequency heme modes. The other transient absorption feature, which is 3.3 times weaker than the bleach signal and shifted $27\;cm^{-1}$ toward lower energies, is attributed to the CN mode in an electronically excited state where the CN bond is weakened with a lowered extinction coefficient. These observations suggest that photoexcited CytcCN mainly undergoes ultrafast radiationless relaxation, causing photo-deligation of $CN^-$ from CytcCN highly inefficient. As also observed in $CN^-$-ligated myoglobin, inefficient ligand photodissociation might be a general property of $CN^-$-ligated ferric hemes.