• Clean Technology
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• v.24 no.1
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• pp.77-84
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• 2018

In this study, $Li_4Ti_5O_{12}$ anode materials for lithium ion battery were synthesized by dry ball-mill method. Polyvinyl chloride (PVC) as a carbon source was added to improve electrochemical properties. When the PVC was added after $Li_4Ti_5O_{12}$ formation, the spinel structure was well synthesized and it was confirmed by X-ray diffraction (XRD) experiments. When the carbon material was added before the synthesis and the heat treatment was performed, it was confirmed that a material having a different crystal structure was synthesized even when a small amount of carbon material was added. In the case of $Li_4Ti_5O_{12}$ without the carbon material, the electrical conductivity value was about $10{\mu}S\;m^{-1}$, which was very small and similar to that of the nonconductor. As the carbon was added, the electrical conductivity was greatly improved and increased up to 10,000 times. Electrochemical impedance spectroscopy (EIS) analysis showed that the size of semicircle corresponding to the resistance decreased with the carbon addition. This indicates that the resistance inside the electrode is reduced. According to the Cyclic voltammetry (CV) analysis, the potential difference between the oxidation peak and the reduction peak was reduced with carbon addition. This means that the rate of lithium ion insertion and deinsertion was increased. $Li_4Ti_5O_{12}$ with 9.5 wt% PVC added sample showed the best properties in rate capabilities of $180mA\;h\;g^{-1}$ at 0.2 C-rate, $165mA\;h\;g^{-1}$ at 0.5 C-rate, and $95.8mA\;h\;g^{-1}$ at 5 C-rate.

• Tuberculosis and Respiratory Diseases
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• v.40 no.2
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• pp.158-164
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• 1993

Background: Recently, lung abscess tends to be increased in patients with underlying disease, most of whom are unsuitable for surgery when medical treatment fails. The patients with giant lung abscesses do not frequently respond to antibiotics and often have life-threatening complications. Therefore, more intensive cares are required in these patients. We studied the results and effects of percutaneous catheter drainage in these patients. Method: We performed fluoroscopy-guided percutaneous pigtail catheter (8.3 F) drainage by Seldinger technique in 9 cases of lung abscess (in 7 cases, intractable to medical treatment for an average of 8.4 days and in 2 cases, catheter drainage immediately performed due to a large cavity that was initially 10 cm in diameter). We compared 10 cases of lung abscess as control group which had receieved conventional medical treatment alone. Results: Seven of the 9 patients in study group of percutaneous drainage and 7 of the 10 patients in control group of medical treatment alone clinically improved in the average of 1.8 and 8.7 days, respectively. The mean duration of drainage was 13.2 days. There were 3 cases of death from massive hemoptysis, asphyxia of pus, and sepsis in control group, as compared with 2 cases of death from hepatic encephalopathy and sepsis in study group. The malfunctions of catheter occurred in these 2 cases, obstruction and dislodgement. But there were no significant pleuropulmonary complications of percutaneous drainage. Conclusion: Percutaneous drainage is effective and relatively safe in the management of lung abscesses refractory to medical therapy or giant lung abscesses.

• Journal of the Korean Orthopaedic Association
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• v.55 no.5
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• pp.405-410
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• 2020

Purpose: Pedicle screw insertion has been traditionally used as a surgical treatment for degenerative lumbar spine disease. As an alternative, the cortical-bone trajectory screw allows less invasive posterior lumbar fixation and excellent mechanical stability, as reported in several biomechanical studies. This study evaluated the clinical and radiological results of a case of early failure of cortical-bone screw fixation in posterior fixation and union after posterior decompression. Materials and Methods: This study examined 311 patients who underwent surgical treatment from 2013 to 2018 using cortical orbital screws as an alternative to traditional pedicle screw fixation for degenerative spinal stenosis and anterior spine dislocation of the lumbar spine. Early fixation failure after surgery was defined as fixation failure, such as loosening, pull-out, and breakage of the screw on computed tomography (CT) and radiographs at a follow-up of six months. Results: Early fixation failure occurred in 46 out of 311 cases (14.8%), screw loosening in 46 cases (14.8%), pull-out in 12 cases (3.9%), and breakage in four cases (1.3%). An analysis of the site where the fixation failure occurred revealed the following, L1 in seven cases (15.2%), L2 in three cases (6.5%), L3 in four cases (8.7%), L4 in four cases (8.7%), L5 in four cases (8.7%), and S1 in 24 cases (52.2%). Among the distal cortical bone screws, fixation failures such as loosening, pull-out, and breakage occurred mainly in the S1 screws. Conclusion: Cortical-bone trajectory screw fixation may be an alternative with comparable clinical outcomes or fewer complications compared to conventional pedicle screw fixation. On the other hand, in case with osteoporosis and no anterior support structure particularly at L5-S1 fusion sites were observed to have result of premature fixation failures such as relaxation, pull-out, and breakage.