• The Korean Journal of Pain
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• v.18 no.2
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• pp.255-258
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• 2005

Many patients with intractable chest pain visit pain clinics, two of which, with rare cases of an intraspinal tumor and malignant mesothelioma were experiences at our clinic. A 37-year old female patient presented with exacerbating chest pain, but without neurological manifestations, of 15-months duration. Her laboratory findings, such as blood tests, chest X-ray, EKG, abdominal ultrasonography and chest CT, were normal. MRI revealed an intradural extramedullary schwannoma at the T 5 and 6 levels of the thoracic spine. She completely recovered following a laminectomy, with removal of the tumor. The other case was a 65-year old male patient, who presented with chest and back pain in the thoracic area of 6 months duration. He had no cough and dyspnea, and was initially misdiagnosed with intercostal neuralgia; therefore, pain control medication was administered, but all trials were ineffective. Finally, chest CT revealed a malignant mesothelioma, with multiple spine metastases. In conclusion, patients with intractable chest pain should be re-examined both clinically and radiographically.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1923-1930
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• 2012

Mn-Cu catalysts were tested for selective catalytic reduction of NOx with NH3. Influence of initial reaction temperature was studied for NOx conversion in which reaction temperature was changed three patterns. NOx conversion of catalysts calcined at 200, 300 and $340^{\circ}C$ was measured during the changing temperature. Hydrogen conversion efficiency of calcined catalysts was also measured in the $H_2$-TPR system. The deactivation effect of $SO_2$ on catalyst was investigated with the on-off control of $SO_2$ supply. The catalyst which calcined above $340^{\circ}C$ was somewhat deactivated with thermal shock. The reason of deactivation was draw from the results of surface area and hydrogen conversion.

• Journal of Korean Neurosurgical Society
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• v.60 no.6
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• pp.749-754
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• 2017

Objective : To quantitatively measure the degree of bone flap resorption (BFR) following autologous bone cranioplasty and to investigate factors associated with BFR. Methods : We retrospectively reviewed 29 patients who underwent decompressive craniectomy and subsequent autologous bone cranioplasty between April 2005 and October 2014. BFR was defined as : 1) decrement ratio ([the ratio of initial BF size/craniectomy size]-[the ratio of last BF/craniectomy size]) >0.1; and 2) bone flap thinning or geometrical irregularity of bone flap shape on computed tomographic scan or skull plain X-ray. The minimal interval between craniectomy and cranioplasty was one month and the minimal follow-up period was one year. Clinical factors were compared between the BFR and no-BFR groups. Results : The time interval between craniectomy and cranioplasty was $175.7{\pm}258.2$ days and the mean period of follow up was $1364{\pm}886.8$ days. Among the 29 patients (mean age 48.1 years, male : female ratio 20 : 9), BFR occurred in 8 patients (27.6%). In one patient, removal of the bone flap was carried out due to severe BFR. The overall rate of BFR was $0.10{\pm}0.11$ over 3.7 years. Following univariate analysis, younger age ($30.5{\pm}23.2$ vs. $54.9{\pm}13.4$) and longer follow-up period ($2204.5{\pm}897.3$ vs. $1044.1{\pm}655.1$) were significantly associated with BFR (p=0.008 and 0.003, respectively). Conclusion : The degree of BFR following autologous bone cranioplasty was 2.7%/year and was associated with younger age and longer follow-up period.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.50.1-50.6
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• 2019

Purpose: Maxillary bone grafts and implantations have increased over recent years despite a lack of maxillary bone quality and quantity. The number of patients referred for oroantral fistula (OAF) due to implant or bone graft failure has increased, and in patients with an oroantral fistula, the pedicled buccal fat pad is viewed as a robust, reliable option. This study was conducted to document the usefulness of buccal fat pad grafts for oroantral fistula closure. Materials and methods: We retrospectively studied 25 patients with OAF treated with a buccal fat pad graft from 2015 to 2018. Sex, age, OAF location, cause, duration, presence of systemic disease, smoking, previous dental surgery, and side effects were investigated. Results: A total of 25 patients were studied. Mean patient age was 54.8 years, and the male to female ratio was 19: 6. Causes of oroantral fistula were cyst enucleation, tumor resection, implant removal, bone graft failure, and extraction. Excellent results were obtained in 23 (92%) of the 25 patients. In the other two patients that both smoked, a small fistula was observed during follow-up. No recurrence of oroantral fistula was observed after 2 months to 1 year of follow-up. Conclusions: The incidence of oroantral fistula is increasing due to implant and bone graft failures. Oroantral fistula closure using a pedicled buccal fat pad was found to have a high success rate.

• Clean Technology
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• v.23 no.1
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• pp.64-72
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• 2017

In this study, the selective catalytic reduction (SCR) for NOx removal was investigated in the temperature range of $150{\sim}400^{\circ}C$. XRD, BET and XPS analyses to determine the structural properties and valence state characteristics of the catalyst were performed. Various ball mill method were shown to a difference in activity at a low temperature below $250^{\circ}C$. Based on the catalyst with the highest denitrification efficiency, the ball mill time was the best result at 3 h. As a result of XPS analysis, the presence of the non-stoichiometric vanadium species and the increase of the number of atoms were attributed to a positive effect in the SCR reaction. it was confirmed that the correlation between the amount of lattice oxygen and the denitrification efficiency through the $O_2$ on-off experiment, and it was in a proportional relationship to each other.

• Advances in pediatric surgery
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• v.19 no.2
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• pp.57-65
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• 2013

The entity of negative appendectomies still poses a dilemma in chlidren. Focused computed tomography (CT) scanning has become the diagnostic test of choice in many hospitals. However, the impact of CT scans on the diagnosis in children is unknown exactly. The purpose of this study was to critically evaluate CT scans for the evaluation of acute appendicitis in children, to review utilization of this diagnostic test in our appendicitis population and to determine if diagnostic accuracy has improved. A retrospective analysis of efficacy of CT scan for diagnosis of appendicitis in children was conducted. Children undergoing appendectomy for acute appendicitis were reviewed from 2007 to 2012. Perforation and negative appendectomy (removal of a normal appendix) rates were determined by the final pathologic report. Statistical comparison were made using the $x^2$ test and significance was assigned at p < 0.05. Five hundred four appendectomies were performed. Mean age was $10.1{\pm}3.21$ years, and 62.7% were boys. Overall, 308 children (61.1%) underwent CT scanning, 100 (19.8%) had US performed, and 97 (19.2%) had no radiographic study. A pathologically normal appendix was removed in 8.7% (27 of 308) of CT patients, 9.0% (9 of 100) of US patients, and 11.3% (11 of 97) of patients without a study. The frequency of CT scanning increased from 29.7% (27 of 91) of all children in 2007 to 75.6% (59 of 78) in 2012, whereas utilization of US decreased from 30.8% (28 of 91) to 11.5% (9 of 78). During this time period the difference in the negative appendectomy rate did change significantly from 14% to 6%. Liberal use of CT scans in diagnosing appendicitis in children has resulted in a decreased negative appendectomy rate.

• Membrane and Water Treatment
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• v.9 no.3
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• pp.163-172
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• 2018

This study investigated the effect of organic matter on the precipitation of struvite and calcium phosphate for phosphorus recovery from synthetic dairy wastewater. Batch precipitation experiments were performed to precipitate phosphorus from solutions containing $PO_4{^{3-}}$ and $NH_4{^+}$ by the addition of $Mg^{2+}$ and $Ca^{2+}$, separately, at varying pH, Mg/P and Ca/P molar ratios, and organic matter concentrations. Soluble total organic solids exhibited more inhibition to precipitation due to potential interaction with other dissolved ionic species involved in phosphorus precipitation. Xylan with low total acidity only exhibited significant inhibition at very high concentrations in synthetic wastewater (at up to 100 g/L). No significant inhibition was observed for Mg and Ca precipitation at relatively lower concentrations (at up to 1.2 g/L). MINTEQ simulations show that dissolved organic matter (DOM) as humic substances (HS) can cause significant inhibition even at relatively low concentrations of 0.165 g/L fulvic acid. However, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis suggested that xylan altered the crystal structure of both precipitates and had caused the formation of smaller sized struvite crystals with slightly rougher surfaces This could be due to xylan molecules adhering on the surface of the crystal potentially blocking active sites and limit further crystal growth. Smaller particle sizes will have negative practical impact because of poorer settleability.

• Korean Journal of Materials Research
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• v.13 no.10
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• pp.691-696
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• 2003

To improve the photocatalyticactivity of $TiO_2$-coated coal fly ash, tungsten hydroxide was doped by impregnation method and was oxidized by heat treatment in temperature ranges of $WO^{\circ}C$ for 2 hrs. The changes of crystal structure and crystal size of $TiO_2$and $WO_3$on coal fly ash were investigated by X-ray diffraction analysis. The crystal structure of titanium dioxide showed only anatase type and $TiO_2$-$WO_3$ compounds appeared in the heat treatment temperature ranges of $500∼600^{\circ}C$. By adding $V_3$in $TiO_2$coated on fly ash, the growth of crystal size of anatase was restrained and the anatase phase was stabilized in temperature ranges of TEX>$500∼<800^{\circ}C$. And $WO_3$acted as a trap site of electrons excited from anatase by irradiating UV. The maximum removal efficiency of NO gas for $TiO_2$/$WO_3$-coated coal fly ash was 84% and appeared when the ammonium tungstate of $1.3${\times}$10^{-3}$ M was doped and then heated at $600^{\circ}C$ for 2 hrs.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.6
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• pp.539-546
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• 2002

The physicochemical properties of solid wastes generated from seven highway service areas, four branch offices, and one construction site were analyzed in concert with air pollutants including heavy metals emitted from near-by small-scale incinerators. The amount of solid wastes generated from highway areas has been increasing with recent increases in the number of highways and passengers. Twelve incinerators examined in this study generally had capacity smaller than 100 kg/hr, most of which were equipped with cyclone for dust removal. It was seen that the concentrations of the gas-phase air pollutants (e.g., SO$_2$, NO$_{x}$, HCl and H$_2$S) were above the acceptable emission standards except one or two sites. CO concentrations at all incinerators were also higher due to incomplete combustion. In addition, particulate matters showed concentration six times higher at their maximum. The results of heavy metal analysis showed that the concentrations of Cu, Cd, and Ni satisfied the emission standards. whereas Pb at one site and Zn at five sites exceeded the standards. Cr measurement results indicated that 9 of 12 incinerators had higher values than the standard; especially one branch office showed nine times higher than normal concentration. In order to satisfy more stringent emission standards in the near future, it is necessary to install air pollution control system and to develop an intensified management plan.n.

• Journal of Powder Materials
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• v.25 no.4
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• pp.316-321
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• 2018

Composites of P25 $TiO_2$ and hexagonal $WO_3$ nanorods are synthesized through ball-milling in order to study photocatalytic properties. Various composites of $TiO_2/WO_3$ are prepared by controlling the weight percentages (wt%) of $WO_3$, in the range of 1-30 wt%, and milling time to investigate the effects of the composition ratio on the photocatalytic properties. Scanning electron microscopy, x-ray diffraction, and transmission electron microscopy are performed to characterize the structure, shape and size of the synthesized composites of $TiO_2/WO_3$. Methylene blue is used as a test dye to analyze the photocatalytic properties of the synthesized composite material. The photocatalytic activity shows that the decomposition efficiency of the dye due to the photocatalytic effect is the highest in the $TiO_2/WO_3$ (3 wt%) composite, and the catalytic efficiency decreases sharply when the amount of $WO_3$ is further increased. As the amount of $WO_3$ added increases, dye-removal by adsorption occurs during centrifugation, instead of the decomposition of dyes by photocatalysts. Finally, $TiO_2/WO_3$ (3 wt%) composites are synthesized with various milling times. Experimental results show that the milling time has the best catalytic efficiency at 30 min, after which it gradually decreases. There is no significant change after 1 hour.