• Wind and Structures
• /
• v.23 no.2
• /
• pp.91-107
• /
• 2016

Flow-excited acoustic resonance in ducted cavities can produce high levels of acoustic pressure that may lead to severe damage. This occurs when the flow instability over the cavity mouth, which is created by the free shear layer separation at the upstream edge, is coupled with one of the acoustic modes in the accommodating enclosure. Acoustic resonance can cause high amplitude fluctuating acoustic loads in and near the cavity. Such acoustic loads could cause damage in sensitive applications such as aircraft weapon bays. Therefore, the suppression and mitigation of these resonances are very important. Much of the work done in the past focused on the fluid-dynamic oscillation mechanism or suppressing the resonance by altering the edge condition at the shear layer separation. However, the effect of the downstream edge has received much less attention. This paper considers the effect of the impingement edge geometry on the acoustic resonance excitation and Strouhal number values of the flow instabilities in a ducted shallow cavity with an aspect ratio of 1.0. Several edges, including chamfered edges with different angles and round edges with different radii, were investigated. In addition, some downstream edges that have never been studied before, such as saw-tooth edges, spanwise cylinders, higher and lower steps, and straight and delta spoilers, are investigated. The experiments are conducted in an open-loop wind tunnel that can generate flows with a Mach number up to 0.45. The study shows that when some edge geometries, such as lower steps, chamfered, round, and saw-tooth edges, are installed downstream, they demonstrate a promising reduction in the acoustic resonance. On the other hand, higher steps and straight spoilers resulted in intensifying the acoustic resonance. In addition, the effect of edge geometry on the Strouhal number is presented.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.7
• /
• pp.2279-2285
• /
• 2011

The geometries, electronic structures and absorption spectra of the two organic triphenylamine-based dyes TA-St-CA and TA-DM-CA, containing identical electron donors and acceptors but the different conjugated bridges, were studied by density functional theory (DFT) at the B3LYP and PBE1PBE levels, respectively. The influence of para-orientating methoxyl units on the electronic structures and light absorption properties of the dyes and the consequent photovoltaic performance of the dye-sensitized solar cells (DSSCs) were investigated in detail. The results indicate that the introduction of the para-orientating methoxyl units into the conjugated bridge induces the increased absorption wavelength as well as the more negative EHOMO corresponding to the bigger driving force $(E_{I^-/I^-_3}-E_{HOMO})$ for dye reduction, which together improve the photovoltaic performance of TA-DM-CA, although there is a decline of the open circuit voltage caused by the more negative $E_{LUMO}$.

• Clinics in Shoulder and Elbow
• /
• v.6 no.1
• /
• pp.44-49
• /
• 2003

Purpose: Many different operative technique of mid-shaft clavicle fracture have been reported. The aim of this prospective study was to compare the results of anterior or anterior-inferior plating with superior plating on the acute mid-shaft fracture of clavicle Materials and Methods: From February1997 to February 2002, thirty-eight consecutive open reduction and internal fixation with reconstruction plates were performed in thirty-eight patients. from August 1999, anterior or anterior-inferior plating was mainly used, prospectively. The duration of follow-up averaged 17 months (range,23 to 43 months). The mean age was 38 years old (range,21 to 57 years old) on anterior or anterior-inferior plating group and 35 years old (range,24 to 55 years old) on superior plating group. The physician progress note, VAS patient complement score, Roentgenogram and ASES score was evaluated. Results: Four patients were lost to follow-up. There was no statistical difference on mean radiological bone union time （8.7 weeks vs. 8.6 weeks) and ASES score (92 vs 94) at inferior and superior plating groups (P > 0.05). VAS patient complement score was very good or excellent on anterior or anterior-inferior group, average score was 1.1 (ranger,0 to 2) compare with superior plating group (P < 0.05). There were two cases of infection, 1 case of failed fixation on superior plating group and 1 case of delayed union on anterior inferior plating group. Conclusion: Anterior inferior plating on acute clavicle midshaft fracture results in excellent patient complement score compare with conventional superior reconstruction plate.

• Clinics in Shoulder and Elbow
• /
• v.20 no.2
• /
• pp.90-94
• /
• 2017

Background: Proximal humerus fracture is considered to be the third most common fracture for patients aged 65 years or older. Conservative treatment has been known to treat most of humerus fracture. However, fractures with severe displacement or dislocation may require surgical treatment. Intramedullary fibular allograft with a locking plate is frequently used in patients accompanying medial metaphyseal disruption. In this study, author intends to evaluate clinical and imaging results based on patients who underwent surgical treatment using fibular allograft with a locking plate. Methods: This study is conducted prospectively at Wonju Severance Christian Hospital, targeting patients who previously underwent surgical treatment using open reduction and intramedullary fibular allograft with a locking plate between 2011 and 2015. A total of 26 patients were evaluated on the following: postoperational clinical assessment measuring Constant score, American Shoulder and Elbow Society (ASES) score, and the Disabilities of the Arm, Shoulder and Hand (DASH) score. Postoperational imaging assessments are evaluated via measuring the neck-shaft angle. The study subject were Neer classification type 3, 4 proximal humerus fracture cases with disrupted medial hinge and having cortical comminution in the region of the surgical neck. Results: The average period of progression was 22.5 months, and the average age of patients was 72.6 years. At the final follow-up, the average Constant, average ASES, and average DASH scores were 80.1, 78.5, and 20.6 respectively. The average neck-shaft angle was $127.5^{\circ}$. Conclusions: In conclusion, fibular allograft augmentation with a locking plate showed satisfying results in both clinical and imaging studies.

• Clinics in Shoulder and Elbow
• /
• v.21 no.3
• /
• pp.120-126
• /
• 2018

Background: Treatment of distal humerus fractures in osteoporotic elderly patients is often challenging. For non-reconstructible fractures with open reduction and internal fixation, total elbow arthroplasty (TEA) is an acceptable alternative. However, the relatively high complication rates and lifelong activity restrictions make TEA less ideal for elderly or low-demand patients. Efforts to identify or develop alternate procedures that benefit relatively young, high-demand patients have resulted in increased interest in hemiarthroplasty. This systematic review reports the clinical outcomes of hemiarthroplasty for distal humeral fractures. Methods: We systematically reviewed the databases of PubMed, Ovid MEDLINE, and Cochrane Library. All English-language studies published before June 2017 were considered for possible inclusion. Search terms included 'distal humerus fracture' and 'hemiarthroplasty'. Studies reporting outcomes (and a minimum of 1 year clinical follow-up) in human subjects after hemiarthroplasty (Latitude system) for distal humeral fractures were assessed for inclusion. Patient demographics, clinical and radiographic outcomes, and complications were recorded, and homogenous outcome measures were analyzed. Results: Nine studies with a total of 115 patients met the inclusion criteria. Among the included studies, the weighted mean follow-up time was 35.4 months. Furthermore, the weighted mean of the postoperative range of motion ($107.6^{\circ}$ flexion-extension, $157.5^{\circ}$ for pronation-supination) and functional outcomes (Mayo elbow performance scores: 85.8, Disabilities of the Arm, Shoulder and Hand score: 19.6) were within the acceptable range. Conclusions: Our study indicates that hemiarthroplasty is a viable option for comminuted distal humerus fracture. Satisfactory functional outcomes were observed in most patients.

• Archives of Plastic Surgery
• /
• v.35 no.6
• /
• pp.675-679
• /
• 2008

Purpose: In the orbital floor fracture, sensory impairment due to the damage of the infraorbital nerve is one of the most common symptom and complication. In this report, we have the assumption that tailoring of $medpor^{(R)}$ for decompression may have correlations to the damage and regeneration of the nerve. Methods: Among patients who had open reduction for pure orbital floor fracture in our hospital from March 2005 to March 2008, we selected 80 cases. In 40 cases, we inserted tailored $medpor^{(R)}$, and in other 40 cases, non-tailored $medpor^{(R)}$ was inserted. Patient's reports were obtained and analyzed, and the pin-prick test and the 2-point discrimination test on the infraorbital nerve regions were done for testing the sensory impairments. Results: The results show that the patients who adopted sculpture of $medpor^{(R)}$ showed higher tendency of recovery of sensory impairments in the patient's subjective report, static touch sensation, static two point discrimination using. And in postoperative 3 months, there are statistically significant recovery of sensory symptoms, signs and the result of sensory tests. Conclusion: From these results, tailored $medpor^{(R)}$ in reconstruction of orbital wall fracture may improve recovery of sensory impairments for decreasing of compression of infraorbital nerve.

• Archives of Plastic Surgery
• /
• v.40 no.6
• /
• pp.721-727
• /
• 2013

Background One of the main concerns in orbital blowout fracture repair is a narrow operation field, due mainly to the innate complex three dimensions of the orbit; however, a deep location and extensive area of the fracture and soft tissue edema can also cause concern. Swelling of the orbital contents progresses as the operation continues. Mannitol has been used empirically in glaucoma, cerebral hemorrhage, and orbital compartment syndrome for decompression. The authors adopted mannitol for the control of intraorbital edema and pressure in orbital blowout fracture repair. Methods This prospective study included 108 consecutive patients who were treated for a pure blowout fracture from January 2007 to October 2012. For group I, mannitol was administered during the operation. Under general anesthesia, all patients underwent surgery by open reduction and insertion of an absorbable mesh implant. The authors compared postoperative complications, the reoperation rate, operation time, and surgical field improvement between the two groups. Results In patients who received intraoperative administration of mannitol, the reoperation rate and operation time were decreased; however, the difference was not statistically significant. The total postoperative complication rates did not differ. Panel assessment for the intraoperative surgical field video recordings showed significantly improved vision in group I. Conclusions For six years, mannitol proved itself an effective, reliable, and safe adjunctive drug in the repair of orbital blowout fractures. With its rapid onset and short duration of action, mannitol could be one of the best methods for obtaining a wider surgical field in blowout fracture defects.

• Archives of Plastic Surgery
• /
• v.43 no.5
• /
• pp.411-417
• /
• 2016

Background Facial hypoesthesia is one of the most troublesome complaints in the management of facial bone fractures. However, there is a lack of literature on facial sensory recovery after facial trauma. The purpose of this study was to evaluate the facial sensory recovery period for facial bone fractures using Neurometer. Methods Sixty-three patients who underwent open reduction of zygomatic and blowout fractures between December 2013 and July 2015 were included in the study. The facial sensory status of the patients was repeatedly examined preoperatively and postoperatively by Neurometer current perception threshold (CPT) until the results were normalized. Results Among the 63 subjects, 30 patients had normal Neurometer results preoperatively and postoperatively. According to fracture types, 17 patients with blowout fracture had a median recovery period of 0.25 months. Twelve patients with zygomatic fracture had a median recovery period of 1.00 month. Four patients with both fracture types had a median recovery period of 0.625 months. The median recovery period of all 33 patients was 0.25 months. There was no statistically significant difference in the sensory recovery period between types and subgroups of zygomatic and blowout fractures. In addition, there was no statistically significant difference in the sensory recovery period according to Neurometer results and the patients' own subjective reports. Conclusions Neurometer CPT is effective for evaluating and comparing preoperative and postoperative facial sensory status and evaluating the sensory recovery period in facial bone fracture patients.

• The Korean Journal of Applied Statistics
• /
• v.29 no.6
• /
• pp.1095-1106
• /
• 2016

The quantile regression method proposed by Koenker et al. (1978) focuses on conditional quantiles given by independent variables, and analyzes the relationship between response variable and independent variables at the given quantile. Considering the linear programming used for the estimation of quantile regression coefficients, the model fitting job might be difficult when large data are introduced for analysis. Therefore, dimension reduction (or variable selection) could be a good solution for the quantile regression of large data sets. Regression tree methods are applied to a variable selection for quantile regression in this paper. Real data of Korea Baseball Organization (KBO) players are analyzed following the variable selection approach based on the regression tree. Analysis result shows that a few important variables are selected, which are also meaningful for the given quantiles of salary data of the baseball players.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.09a
• /
• pp.175-178
• /
• 2004

Little study has been published specifically addressing the dynamics of nitrate reducing bacteria (NBR) during the bioremediation of nitrate-contaminated aquifer. In our previous study we successfully quantified fumarate-enhanced microbial nitrate reduction rate in a nitrate-contaminated aquifer by using a series of single-well push-pull tests (PPTs). In this study we analyzed the suspended population during PPTs. To monitor changes in the microbial community, PCR amplification of 16S rDNA genes and denaturing gradient gel electrophoresis (DGGE) were used to study the dynamics of the bacterial community in detail. Before the stimulation of NBR, the dominant DGGE bands obtained by PCR were affiliated with V-Proteobacteria consisting of Acinetobacter spp. and Pseudomonas fluorescens. However, as NBR biostimulation proceeded, the dominant patterns of DGGE bands changed, and they were affiliated with Azoarcus denitrificans Td-3 and Flavobacterium xanthum. Azoarcus denitrificans Td-3 is known to completely reduce nitrate to nitrogen gas. The series of single-well push-pull tests in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ denitrification and provide important information about which microorganisms play a key role in bioremediation of a nitrate contaminated aquifer.