• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.349-352
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• 2001

The transient response in TDFA(Thulium-Doped Fiber Amplifier) is theoretically investigated. The TDFA has the spectral gain band in 1.47 ${\mu}{\textrm}{m}$. The transient model includes the transient buildup of the population inversion, the pump power, the signal power and their transient variation along the fiber amplifier. The results of numerical analysis can predict the gain saturation and recovery time at the fiber amplifier. It also shows the gain saturation and recovery effect depending on the pumping and saturation rate.

• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.330-334
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• 2000

A new pha~e lock loop (PLL) IS proposed and demonstrated fat clock recovery from 40 Gblt/s time-dIvision-multiplexed (TDM) optical pulse tri.lin, The proposed clock lecovery scheme lmproves the Jitter effecl cOlmng from the clock. pulse laser of harmonically-mode locked flber laser The cross-corrdation frequency component between the optical Signa] and an optical clock pulse tram is deteCled as a fonr-wave-mixing (FWM) SIgnal generated in SOA. The lock-in freqnency range of the clod. recovery IS found to be within 10 KHz. 0 KHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.365-370
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• 2004

In this paper, complexity secure communication was presented. The complexity circuit is used to State-Controlled Cellular Neural Network(SC-CNN). We make a complexity circuit using SC-CNN with the N-double scroll. A complexity circuit is created by applying identical n-double scrolls with coupled method, to each cell. complexity synchronization was achieved using drive response synchronization between the transmitter and receiver about each state in the SC-CNN. From the result of the recovery signal through the demodulation method in the receiver. We shown that recovery quality in the receiver is the similar to other secure communication methods.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.166-170
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• 2000

A wavelength tunable all-optical clock recovery using a semiconductor optical amplifier in a fiber ring cavity is proposed and demonstrated at the wavelength of 1530 nm to 1570 nm. A synchronized optical pulse train is recovered from 10 Gbps and 30 Gbps randomly generated optical pulse streams with injection locking technique. Also, the system responses to the perturbation and the input average power variation are analyzed by a large-signal model based on time-domain travelling wave equation. ation.

• Journal of Korean Neurosurgical Society
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• v.41 no.6
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• pp.421-424
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• 2007

Two patients, one with glioblastoma multiforme [GM] in the right thalamus and the other with meningioma at the right frontal convexity, had suffered bilateral cortical blindness after transtentorial herniation. On one of those patients, bilateral cortical blindness had occurred due to acute obstructive hydrocephalus caused by GM and on the other patient, cortical blindness had developed after acute hemorrhage from meningioma. Bilateral occipital lobes of those patients showed signal change on the brain magnetic resonance image [MRI]. There were no ophthalmologic abnormalities on fundoscopy and ophthalmologic examination. After recovery of consciousness, cortical blindness was detected in both patients, and during gradual recovery period, visual function was slowly recovered. The pattern of visual evoked potential [VEP] at 7 weeks and 12 weeks after herniation was normalized gradually. Cortical blindness due to herniation was reversible, even though the high signals of bilateral visual cortex still existed on MRI 16 month later in case 2.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.149-152
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• 1998

A synchronization is very important element not only wire communication but also wireless communication. A synchronous oscillator(SO) is a network which synchronizes, tracks, filter, amplifies and divides (if necessary) in a single process. The coherent phase synchronous oscillator(CPSO) is created by adding two external loops to the SO. The CPSO ratains all virtues of a SO while providing coherency throughout the tracking range. This paper has applied a clock recovery of GPS signal using CPSO.

• Korean Journal of Radiology
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• v.22 no.7
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• pp.1163-1171
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• 2021

Objective: To analyze the correlations between intraoperative ultrasound and MRI metrics of the spinal cord in degenerative cervical myelopathy and identify novel potential predictive ultrasonic indicators of neurological recovery for degenerative cervical myelopathy. Materials and Methods: Twenty-two patients who underwent French-door laminoplasty for multilevel degenerative cervical myelopathy were followed up for 12 months. The Japanese Orthopedic Association (JOA) scores were assessed preoperatively and 12 months postoperatively. Maximum spinal cord compression and compression rates were measured and calculated using both intraoperative ultrasound imaging and preoperative T2-weight (T2W) MRI. Signal change rates of the spinal cord on preoperative T2W MRI and gray value ratios of dorsal and ventral spinal cord hyperechogenicity on intraoperative ultrasound imaging were measured and calculated. Correlations between intraoperative ultrasound metrics, MRI metrics, and the recovery rate JOA scores were analyzed using Spearman correlation analysis. Results: The postoperative JOA scores improved significantly, with a mean recovery rate of 65.0 ± 20.3% (p < 0.001). No significant correlations were found between the operative ultrasound metrics and MRI metrics. The gray value ratios of the spinal cord hyperechogenicity was negatively correlated with the recovery rate of JOA scores (ρ = -0.638, p = 0.001), while the ventral and dorsal gray value ratios of spinal cord hyperechogenicity were negatively correlated with the recovery rate of JOA-motor scores (ρ = -0.582, p = 0.004) and JOA-sensory scores (ρ = -0.452, p = 0.035), respectively. The dorsal gray value ratio was significantly higher than the ventral gray value ratio (p < 0.001), while the recovery rate of JOA-motor scores was better than that of JOA-sensory scores at 12 months post-surgery (p = 0.028). Conclusion: For degenerative cervical myelopathy, the correlations between intraoperative ultrasound and preoperative T2W MRI metrics were not significant. Gray value ratios of the spinal cord hyperechogenicity and dorsal and ventral spinal cord hyperechogenicity were significantly correlated with neurological recovery at 12 months postoperatively.

• Journal of the Korean Society of Radiology
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• v.7 no.4
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• pp.265-269
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• 2013

This report aims at picturing out the clinical usefulness by analyzing the signal intensity in choroid plexuses which produce cerebrospinal fluids by diffusion weighted imaging. At first, subjects were chosen among the patients who showed high in signal intensity by diffusion weighted imaging. The subjects were taken another test by fluid attenuated inversion recovery diffusion weighted echo planer image(FLAIR-DW-EPI) the signals of fluid attenuation. And it was found that there are differences between the signal intensities of the two methods, which showed that the signal intensity in FLAIR-DW-EPI is equal to or low than, that in the Brain. By this, it is felt that it is helpful to diagnose the disease in choroid plexus by testing another more with FLAIR-DW-EPI methods the patients who showed high in signal intensity in choroid plexus by $T2^*$ diffusion weighted echo planer image($T2^*$-DW-EPI).

• Journal of radiological science and technology
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• v.38 no.3
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• pp.253-259
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• 2015

The information of contrast media concentration on target organ is very important to get reduce the side effect and high contrast imaging. We investigated alternation of signal intensity as a function of the modality of Gd-based contrast media on spin echo and ultra short time echo (UTE) of T1 effective pulse sequence at 3T MRI unit. Gadoxetic acid, which is a MRI T1 contrast medium, was used to manufacture an agarose phantom diluted in various molarities, and sterile water and agarose 2% were used as the buffer solution for the dilution. The gold standard T1 calculation was based on coronal single section imaging of the phantom mid-point with 2D Inversion recovery spine-echo pulse sequence MR imaging for testing of phantom accuracy. The 1-2mmol/L and 7mmol/L was shown the maximum signal intensity on spin echo and UTE respectively. We confirm the difference of contrast media concentration which was shown the maximum signal intensity depending on the T1 effective pulse sequence.

• Journal of Korean Society of Transportation
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• v.31 no.5
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• pp.60-70
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• 2013

This study aims to develop a truck priority on left-turn algorithm that can reduce greenhouse gas emissions by reducing heavy duty truck's stops at signalized intersection. The signal priority is granted for a left-turn phase, because heavy duty trucks can deteriorate left-turn traffic flow due to the low acceleration or deceleration rate and large turn radius. Truck priority allows to provide the stable speed control for heavy duty truck, and reduces emissions at the signal intersection. Also, two signal recovery strategies are compared for various traffic conditions. This study analyzes the effectiveness of truck priority such as greenhouse gas emissions and fuel consumption reduction, and total travel time saving using the PARAMICS and Comprehensive Modal Emissions Model (CMEM). The results show that signal priority for heavy duty trucks has an effect on reducing greenhouse gas emissions and fuel consumptions at non-peak hour. Also, it shows decreasing total travel time due to reducing truck stops.