• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.309-316
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• 2013

Since the solar activity, one of the factors influencing on lunar communication systems, is to reach its maximum occurring at 11-year solar cycle in autumn 2013, the solar burst frequency and strength are expected to increase. The solar burst has an effect on earth magnetosphere and causes malfunction, loss of communication, and breakdown of various types of satellites and probes. These problems give rise to huge economic and physical loss. Therefore, we should analyze the effect of solar burst on lunar communications and minimize the expected loss. In this paper, we perform the analysis of the link model and link performance between a land station and a lunar orbiter under the solar burst for orbiter's survivability and stable communication channel operations.

• Journal of Korean Neurosurgical Society
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• v.37 no.6
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• pp.416-421
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• 2005

Objective: Despite general agreement on the goals of surgical treatment in thoracolumbar burst fractures, considerable controversy exists regarding the choice of operative techniques. This study is to evaluate the efficacy of short-segment fixation for thoracolumbar burst fractures after long-term follow-up and to analyze the causes of treatment failures. Methods: 48 out of 60 patients who underwent short-segment fixation for thoracolumbar burst fractures between January 1999 and October 2002 were enrolled in this study. Their neurological status, radiological images, and hospital records were retrospectively reviewed. Simple radiographs were evaluated to calculate kyphotic angles and percentages of anterior body compression (%ABC). Results: The average kyphotic angles were $20.0^{\circ}$ preoperatively, $9.6^{\circ}$ postoperatively, and $13.1^{\circ}$ at the latest follow-up. The average %ABC were 47.3% preoperatively, 31.2% postoperatively, and 33.3% at the latest follow-up. The treatment failure, defined as correction loss by $10^{\circ}$ or more or implant failure, was detected in 6 patients (12.5%). 5 out of 6 patients had implant failures. 2 out of 5 patients were related with osteoporosis, and the other 2 were related with poor compliance of spinal bracing. 3 patients with poor initial postoperative alignment had implant failure. 4 patients with screws only on the adjacent vertebrae and not on the injured vertebra itself showed poor initial and overall correction. Conclusion: With proper patient selection, adequate intraoperative reduction with screw fixation involving the injured vertebra, and strict postoperative spinal bracing, the short-segment fixation is an efficient and safe method in the treatment of thoracolumbar burst fracture.

• Journal of Korean Neurosurgical Society
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• v.41 no.5
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• pp.291-294
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• 2007

Objective : The purpose of this retrospective clinical study was to describe a treatment for osteoporotic burst fracture in the setting of severe fractures involving fragmentation of the posterior wall and neural compromise with symptoms of cord compression. Methods : Indication for microscopic decompression and open kyphoplasty were intractable pain at the level of a known osteoporotic burst fractures involving neural compression or posterior wall fragmentation. A total of 18 patients [mean age, 74.6 years] with osteoporotic thoracolumbar burst fractures [3 males, 15 females] were included in this study. In all cases, microscopic decompressive laminectomy was followed by open kyphoplasty. Clinical outcome using VAS score and modified MacNab's grade was assessed on last clinical follow up [mean 6.7 months]. Radiological analysis of sagittal alignment was assessed preoperatively, immediately postoperatively, and at final follow up. Results : One level augmentation and 1.8 level microscopic decompression were performed. Mean blood loss was less than 100 ml and there were no major complications. The mean pain score before operation and at final follow up was 7.2 and 1.9, respectively. Fourteen of 18 patients were graded as excellent and good according to the modified MacNab's criteria. Overall, 6.0 degrees of sagittal correction was obtained at final follow-up. Conclusion : The combined thoracolumbar microscopic decompression and open kyphoplasty for severe osteoporotic fractures involving fragmentation of posterior wall and neural compromise provide direct visualization of neural elements, allowing safe cement augmentation of burst fractures. Decompressive surgery is possible and risk of epidural cement leakage is controlled intraoperatively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12B
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• pp.1037-1043
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• 2006

There has been proposed an algorithm to reduce data burst processing delay in group scheduling in core nodes of optical burst switching networks. Since, in this algorithm, look-up tables containing all the void time information in scheduling windows are generated as soon as the primary group scheduling session terminates, it becomes faster to reassign dropped data bursts to proper voids in different data channels by referring to the tables. The group scheduling with this algorithm showed almost the same channel utilization as the one without using the algorithm but performed a little better in both burst loss probability and wavelength conversion rate. On the other hand, per-burst processing time has been reduced dramatically in the load region of higher than 0.8, showing a factor of 2.1 reduction at 0.9.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9A
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• pp.669-677
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• 2003

In spite of many advantages of Meteor Burst Communications(MBC) on its transmission channel, the fact that its duty rate is less than10 percents is a considerable deficiency of MBC. To overcome with this deficiency without paying large cost, we use a direct sequence(DS)-spread spectrum(SS) method applying a reference code to improve the duty rate on the transmission channel. This method doesn't need to add the components for acquisition or tracking the signal so that it keeps the cost efficiency the MBC has as well as improves the duty rate on the transmission channel. The improvement by this method is more significant when the received signal is weak. Simulation results show that if we increases the process gain (Gp) by 10 dB when the average burst length is 50ms, the burst length tends to be extended more than 220% of its average length, 160ms, and the frequency of generating this phenomenon increases 3.1 times more.

• Journal of The Korean Astronomical Society
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• v.38 no.4
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• pp.437-443
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• 2005

The Solar Radio Burst Locator (SRBL) is a spectrometer that can observe solar microwave bursts over a wide band (0.1-18 GHz) as well as detect the burst locations without interferometry or mechanical scanning. Its prototype has been operated at Owens Valley Radio Observatory (OVRO) since 1998. In this study, we have evaluated the capability of the SRBL system in flux and radio burst location measurements. For this, we consider 130 microwave bursts from 2000 to 2002. The SRBL radio fluxes of 53 events were compared with the fluxes from USAF/RSTN and the burst locations of 25 events were compared with the optical flare locations. From this study, we found: (1) there is a relatively good correlation (r = 0.9) between SRBL flux and RSTN flux; (2) the mean location error is about 8.4 arcmin and the location error (4.7 arcmin) of single source events is much smaller than that (14.9 arcmin) of multiple source events; (3) the minimum location error usually occurred just after the starting time of burst, mostly within 10 seconds; (4) there is a possible anti-correlation (r = -0.4) between the pointing error of SRBL antenna and the location error. The anti-correlation becomes more evident (r=-0.9) for 6 strong single source events associated with X-class flares. Our results show that the flux measurement of SRBL is consistent with that of RSTN, and the mean location error of SRBL is estimated to be about 5 arcmin for single source events.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.6 no.1
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• pp.113-119
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• 2011

Objectives: The purpose of this study is to investigate the clinical application of Chungungyukgye-tang(Chuanxiongrougui-tang) to one patient with lumbar burst fracture. Methods: Patient is hopitalized at Dept. of Oriental Internal Medicine, Bu-Chun Jaseng Oriental Medicine Hospital, diagnosed as lumbar burst fracture and treated mainly with herbal medine ; Chungungyukgye-tang(Chuanxiongrougui-tang). This study was measured by ODI(Oswestry Disability Index) and NRS(Numeric Rating Scale) score. Results: After taking Chungungyukgye-tang(Chuanxiongrougui-tang), the patient's pain was controlled. NRS & ODI score were decreased. Conclusions: As seen in this one case of lumbar burst fracture, Chungungyukgye-tang(Chuanxiongrougui-tang) has a positive effect to control pain with lumbar burst fracture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.2013-2022
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• 1996

Cyclic Codes can be used for burs(or time slot) synchronization as well as error detection as that the overhead bits of the burst, which would be nessary to seperate burst synchronization and error detection systems, may be eliminated. In this paper a new method for combined burst synchronization and error detection is proposed which requires CRC decoding once only, while the previous method which inspects channel error after searching for burst synchronization requeires CRC decoding twice. The proposed method has the advantage of simple implementation and reducing processing time over the previous one, still showing the same detection perfdormance. It may occur that a burst different from the actually transmitted one is falsely accepted in the presence of channel errors. The exact expression for the false acceptance probability is newly presented through a simple derivation basied on the fact that it is determined by channel errors but not by detection methods.

• Geomechanics and Engineering
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• v.14 no.4
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• pp.337-344
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• 2018

The study of the mining effect influenced by a normal fault has great significance concerning the prediction and prevention of fault rock burst. According to the occurrence condition of a normal fault, the stress evolution of the working face and fault plane, the movement characteristics of overlying strata, and the law of fault slipping when the working face advances from footwall to hanging wall are studied utilizing UDEC numerical simulation. Then the inducing-mechanism of fault rock burst is revealed. Results show that in pre-mining, the in situ stress distribution of two fault walls in the fault-affected zone is notably different. When the working face mines in the footwall, the abutment stress distributes in a "double peak" pattern. The ratio of shear stress to normal stress and the fault slipping have the obvious spatial and temporal characteristics because they vary gradually from the higher layer to the lower one orderly. The variation of roof subsidence is in S-shape which includes slow deformation, violent slipping, deformation induced by the hanging wall strata rotation, and movement stability. The simulation results are verified via several engineering cases of fault rock burst. Moreover, it can provide a reference for prevention and control of rock burst in a fault-affected zone under similar conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6A
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• pp.627-633
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• 2006

In spite of many advantages of Meteor Burst Communications(MBC) on its transmission channel, the fact that its duty rate is less than 10 percents is a considerable deficiency of MBC. To overcome with this deficiency without paying large cost, we use a direct sequence(DS) simple reception system. This method doesn't need to add the components for acquisition or tracking the signal so that it keeps the cost efficiency of the MBC. But it has a disadvantage that its duty rate shows a large decline by noise. For this problem we adopt the proposed system applying a transversal filter circuit. The improvement by this method is more significant when the received signal is weak Simulation results show as t1 is 100ms, then the burst length would be increased by 35% when the initial value of the received signal power increases by 3 dB, t2 is 135ms. If the power increases by 6dB the burst length would be 170ms thus increased by 70%, which shows a great enhancement. Suppose now that t1 is 50ms and the power is increased by 3dB, then t2 would be increased by 70% to 85ms, and increasing the power by 6dB it would be increased by 130% to 115ms.