• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.4
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• pp.372-380
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• 2005

Condylar process of mandible, has the specialized anatomic structure compared with any other body structure, acts directly in connection with mastication and speech and so on. In general, mandibular condyle fractures have been managed by two methods as open and closed reduction. But, there are no reasonable consensus about the proper management of this injury. This study was designed for analysis of the prognosis of two methods of treatment, open and closed reduction, with positional change of fractured condyle and complications within 6 months post-intermaxillary fixation period. We conducted a retrospective analysis of 154 patients whose unilateral mandibular condyle fractures were treated by open or closed reduction in our department. The horizontal, sagittal, and coronal change of the condyle was examined using modified Towne's and panoramic radiographs before intermaxillary fixation(IMF), immediately after IMF, and at 6 months after IMF. Patients, whose mandibular condyle fractures were treated by closed reduction, had significantly shorter ramus height on the side of injury(P<0.05). But, fractured condylar fragments were displaced insignificantly with aspect to sagittal and coronal plane(P>0.05). The level of the fracture influenced the ramus length and the degree of coronal change in the closed reduction group(P<0.05). There was no significant correlation among the level of the fracture, treatment methods and complications(P>0.05). From the results obtained in this study, fractured mandibular condyles, were treated by closed reduction, had a tendency that continuous condylar displacement was occurred with aspect to horozontal and coronal plane in treatment period including intermaxillary fixation. And then there was a correlation between the level of the fracture and the position change in close reduction group statistically. These result suggested that care must be taken in basing treatment decisions on the degree of displacement of the condyle and in treating the mandibular condyle fractures for a long time.

• Journal of Oral Medicine and Pain
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• v.25 no.1
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• pp.73-85
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• 2000

The purposes of the study were (1) to see if there are various types of disc configuration in normal temporomandibular joint and, if so, (2) to examine whether a specific type of disc configuration is susceptible to disc displacement, and (3) to see if a specific type of disc configuration and position is related to early relief of clinical symptoms from the anterior disc displacement without reduction to conservative treatment. From the magnetic resonance (MR) images taken for the patients with symptoms of temporomandibular disorders, 235 images as normal joint group, 255 images as anterior disc displacement with reduction group, and 249 images as anterior disc displacement without reduction group were selected, After the TMJ image was scanned and processed with Photoshop program, the disc configuration was determined, The incidence of various types of disc configuration was analyzed according to age, sex, diagnostic group, and the promptness of symptom relief. The disc position was also examined in relation to the promptness of symptom relief. The results were as follows : 1. In the normal joint group, biconcave type appeared most frequently and reversed, biplanar type in order, Posterior band enlarged and folded type didn't appear at all. On the other hand, in the anterior disc displacement without reduction group, folded type appeared most frequently and also posterior band enlarged type were found often. 2. There were statistically significant differences between sex and configuration of disc in the normal joint group and no statistically significant differences in the anterior disc displacement with reduction group and anterior disc displacement without reduction group, 3. There were no statistically significant differences between age and configuration of disc in the normal, anterior disc displacement with reduction group and anterior disc displacement without reduction group. 4. In anterior disc displacement without reduction group, rapid response was observed in biconcave and reversed type and delayed response was observed in folded type.

• Archives of Craniofacial Surgery
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• v.22 no.2
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• pp.93-98
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• 2021

Background: Pediatric nasal fractures, unlike adult nasal fractures, are treated surgically as early as 7 days after the initial trauma. However, in some cases, a week or more elapses before surgery, and few studies have investigated the consequences of delayed surgery for pediatric nasal fractures. The purpose of this study was to evaluate the postoperative outcomes of pediatric nasal fractures according to the time interval between the initial trauma and surgery. Methods: The records of pediatric patients under 12 years old who underwent closed reduction of nasal bone fracture from March 2012 to February 2020 were reviewed. The interval between trauma and surgery was divided into within 7 days (early reduction) and more than 7 days (delayed reduction). Postoperative results were classified into five grades (excellent, good, moderate, poor, and very poor) based on the degree of reduction shown on computed tomography. Results: Ninety-eight patients were analyzed, of whom 51 underwent early reduction and 47 underwent delayed reduction. Forty-two (82.4%) of the 51 patients in the early reduction group showed excellent results, and nine (17.6%) showed good results. Thirty-nine (83.0%) of the 47 patients in the delayed reduction group showed excellent results and eight (17.0%) showed good results. No statistically significant difference in outcomes was found between the two groups (chi-square test p= 0.937). However, patients without septal injury were significantly more likely to have excellent postoperative outcomes (chi-square test p< 0.01). Conclusion: No statistically significant difference was found in the outcomes of pediatric nasal fractures between the early and delayed reduction groups. Successful surgical results were found even in patients who received delayed reduction (more than 7 days after trauma).

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.313-318
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• 2013

In order to investigate the effect of $V_2O_5$ loading of $V_2O_5-WO_3/TiO_2$ catalyst on the NO reduction and the formation of $N_2O$, the experimental study was carried out in a differential reactor using the powder catalyst. The NO reduction and the ammonia oxidation were, respectively, investigated over the catalysts compose of $V_2O_5$ content (1~8 wt%) based on the fixed composition of $WO_3$ (9 wt%) on $TiO_2$ powder. $V_2O_5-WO_3/TiO_2$ catalysts had the NO reduction activity even under the temperature of $200^{\circ}C$. However, the lowest temperature for NO reduction activity more than 99.9% to treat NO concentration of 700 ppm appeared at 340 with very limited temperature window in the case of 1 wt% $V_2O_5$ catalyst. And the temperature shifted to lower one as well as the temperature window was widen as the $V_2O_5$ content of the catalyst increased, and finally reached at the activation temperature ranged $220{\sim}340^{\circ}C$ in the case of 6 wt% $V_2O_5$ catalyst. The catalyst of 8 wt% $V_2O_5$ content presented lower activity than that of 8 wt% $V_2O_5$ content over the full temperature range. NO reduction activity decreased as the $V_2O_5$ content of the catalyst increased above $340^{\circ}C$. The active site for NO reduction over $V_2O_5-WO_3/TiO_2$ catalysts was mainly related with $V_2O_5$ particles sustained as the bare surface with relevant size which should be not so large to stimulate $N_2O$ formation at high temperature over $320^{\circ}C$ according to the ammonia oxidation. Currently, $V_2O_5-WO_3/TiO_2$ catalysts were operated in the temperature ranged $350{\sim}450^{\circ}C$ to treat NOx in the effluent gas of industrial plants. However, in order to save the energy and to reduce the secondary pollutant $N_2O$ in the high temperature process, the using of $V_2O_5-WO_3/TiO_2$ catalyst of content $V_2O_5$ was recommended as the low temperature catalyst which was suitable for low temperature operation ranged $250{\sim}320^{\circ}C$.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.73-82
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• 2012

The main and side reactions of the three selective catalytic reduction (SCR) reactions with ammonia over a vanadium-based catalyst have been investigated using synthetic gas mixtures in the temperature range of $170{\sim}590^{\circ}C$. The three SCR reactions are standard SCR with pure NO, fast SCR with an equimolar mixture of NO and $NO_2$, and $NO_2$ SCR with pure $NO_2$. Vanadium based catalyst has no significant activity in NO oxidation to $NO_2$, while it has high activity for $NO_2$ decomposition at high temperatures. The selective catalytic oxidation of ammonia and the formation of nitrous oxide compete with the SCR reactions at the high temperatures. Water strongly inhibits the selective catalytic oxidation of ammonia and the formation of nitrous oxide, thus increasing the selectivity of the SCR reactions. However, the presence of water inhibits the SCR activity, most pronounced at low temperatures. In this study, the experimental results are analyzed by means of a dynamic one-dimensional isothermal heterogeneous plug-flow reactor (PFR) model according to the Eley-Rideal mechanism.

• Journal of the Korean Society of Combustion
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• v.4 no.2
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• pp.63-74
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• 1999

The effects of EGR and premixedness on NO formation have been numerically investigated. The flame structure is classified into three categories; premixed flame($=1)$, rich/lean premixed flame(${\alpha}=0.6$ and 0.8) and diffusion flame(${\alpha}=0$). NO formation/destruction mechanisms are assorted to thermal, reburn and Fenimore mechanisms. The temperature of unburned gas is arranged to 298 and 500 K to have access to the condition in a real internal combustion engine. The results show that all three NO formation/destruction reaction rates in the fuel rich flame zone could be decreased by EGR for rich/lean premixed flames, while those in the fuel lean flame zone are not significantly changed. Near the stagnation plane, however, only the thermal NO reaction rate is decreased. The contribution of reburn and Fenimore mechanisms for the net NO production becomes less significant as the premixedness of a flame increases. The larger amount of NO reduction with EGR is expected under the higher temperature and/or higher fuel/air premixedness conditions due to the increased contribution of the thermal mechanism. The role of Fenimore and reburn mechanisms could be important for rich premixed and diffusion flames; therefore, the effect of EGR on NO reduction could vary with fuel/air premixedness. The premixedness of a partially premixed flame changes the flame structure and could affect the NO production characteristics.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.630-638
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• 2009

A computational fluid dynamics(CFD) model is developed and validated with on-site experiments for a urea-based SNCR(selective non-catalytic reduction) process to reduce the nitrogen oxides($NO_x$) in a municipal incinerator. The three-dimensional turbulent reacting flow CFD model having a seven global reaction mechanism under the condition of low CO concentration and 12% excess air and droplet evaporation is used for fluid dynamics simulation of the SNCR process installed in the incinerator. In this SNCR process, urea solution and atomizing air were injected into the secondary combustor, using one front nozzle and two side nozzles. The exit temperature($980^{\circ}C$) of simulation has the same value as in situ experiment one. The $NO_x$ reduction efficiencies of 57% and 59% are obtained from the experiment and CFD simulation, respectively at NSR=1.8(normalized stoichiometric ratio) for the equal flow rate ratio from the three nozzles. It is observed in the CFD simulations with varying the flowrate ratio of the three nozzles that the injection of a two times larger front nozzle flowrate than the side nozzle flowrate produces 8% higher $NO_x$ reduction efficiency than the injection of the equal ratio flowrate in each nozzle.

• Journal of Integrative Natural Science
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• v.1 no.3
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• pp.192-194
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• 2008

A series of non-free hydride reducing systems containing boron or aluminum atom, which possess no metal-hydride bond but an available hydrogen at a branched ${\beta}$-position, has been applied to the selective reduction (chemo--, regio-, and stereoselective reduction) of organic compounds. The systems, comprised of diisopinocampheylborane and diisobutylalane derivatives, exhibited almost perfect selectivities in the reduction of aldehydes and ketones. The characteristics features of this systems leading to a perfect transformation have been depicted in this report, especially in the 1) Reduction of ${\alpha}$,${\beta}$-Unsaturated Carbonyl Compounds to Allylic Alcohols via 1,2-Reduction, 2) Chemoselective Reduction between Structurally Different Carbonyl Compounds, and 3) Stereoselective Reduction of Cyclic Ketones.

• Journal of Environmental Science International
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• v.15 no.4
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• pp.333-340
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• 2006

A (5 wt.%)Mn-(1 wt.%)$V_{2}O_{5}/TiO_{2}$ catalyst were prepared by co-precipitation method and used for low-temperature selective catalytic reduction (SCR) of $NO_x$ with ammonia in the presence of oxygen. The properties of the catalysts were studied by X-ray diffraction (XRD), temperature programmed reduction (TPR) and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS). The experimental results showed that (5 wt.%)Mn-(1 wt.%)$V_{2}O_{5}/TiO_{2}$ catalyst yielded 81% NO conversion at temperature as low as $150^{\circ}C$ and a space velocity of $2,400\;h^{-1}$. Crystalline phase of $Mn_{2}O_3$ was present at ${\ge}\;15%$ Mn on $V_{2}O_{5}/TiO_{2}$. XRD confirmed the presence of manganese oxide ($Mn_{2}O_{3}$) at $2{\theta}=32.978^{\circ}(222)$. The XRD patterns presented of (5 wt.%)Mn-(1 wt.%)$V_{2}O_{5}/TiO_{2}$ did not show intense or sharp peaks for manganese oxides and vanadia oxides. The TPR profiles of (5 wt.%)Mn-(1 wt.%)$V_{2}O_{5}/TiO_{2}$ catalyst showed main reduction peat of a maximum at $595^{\circ}C$.

• Korean Journal of Materials Research
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• v.32 no.4
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• pp.223-229
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• 2022

A porous photocatalyst concrete filter was successfully produced to remove NOx, by mixing TiO₂ photocatalyst with lightweight aerated concrete. Ultra Fine Bubbles were used to form continuous pores inside the porous photocatalytic concrete filter, which was mixed via a bubble generation experiment. The optimal mixing condition was determined to be with 4 % of the bubble generation agent B. NO removal specimens were prepared for various photocatalytic loading conditions, and the specimen containing 3 % P-25 removed NO at a concentration of 1.03 µmol in 1 h. The NO removal rate of the porous photocatalytic concrete filter prepared in this study was 10.99 %. This photocatalytic filter performance was more than 9 times the amount of NO removed by a general photocatalytic filter. The porous photocatalyst concrete filter for removing NOx developed in this study can be applied to various construction sites and the air quality can be solved by reducing NOx contributing to the formation of fine particles.