• 상하수도학회지
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• 제29권1호
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• pp.77-88
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• 2015

Soil column experiments were evaluated effects of silver nanoparticles (i.e., 0, 2.5, 5, and 10 mg/L) on the microbial viability which is strongly associated with the degradation of organic matter, pharmaceutically active compounds(PhACs) and biological oxidation of nitrogenous compounds during river bank filtration. The addition of silver nanoparticles resulted in almost no change in the aqueous matrix. However, the intact cell concentration decreased with addition of silver nanoparticles from 2.5 to 10 mg/L, which accounted for 76% to 82% reduction compared to that of control (silver nanoparticles free surface water). The decrease in adenosine triphosphate was more pronounced; thus, the number and active cells in aqueous phase were concurrently decreased with added silver nanoparticles. Based on the florescence excitation-emission matrix and liquid chromatograph - organic carbon detection analyses, it shows that the removal of protein-like substances was relatively higher than that of humic-like substances, and polysaccharide was substantially reduced. But the extent of those substances removed during soil passage was decreased with the increasing concentration of silver nanoparticles. The attenuation of ionic PhACs ranged from 55% to 80%, depending on the concentration of silver nanoparticles. The attenuation of neutral PhACs ranged between 72% and 77%, which was relatively lower than that observed for the ionic PhACs. The microbial viability was affected by silver nanoparticles, which also resulted in inhibition of nitrifiers.

• Environmental Engineering Research
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• 제25권3호
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• pp.316-323
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• 2020

The degradation of aqueous oxytetracycline (OTC) from an aqueous solution antibiotic using H₂O₂/Fe²⁺ process was studied in one 1 L batch chemical reactor. The extent of OTC degradation (20 mg/L) was investigated from a known initial pH solution, temperature and the type of catalyst (Fe²⁺, Fe³⁺) and for various initial concentrations of OTC, H₂O₂ and Fe²⁺. The degradation efficiency achieved was found to be very important (90.82% and 90.63%) at initial pH solution of 3 and 4, respectively. However, the type of catalyst and the reaction temperature had a slight impact on the final degradation of OTC. The results showed that the OTC removal increased with increasing initial H₂O₂ concentration in the range of 70 to 150 mg/L and initial Fe²⁺ concentrations in the range of 2 to 5 mg/L. The highest degradation efficiency obtained at ambient temperature was 90.95% with initial concentration of OTC of 10 mg/L, H₂O₂ = 150 mg/L and Fe²⁺ = 5 mg/L. Moreover, biodegradability improved from 0.04 to 0.36 and chemical oxygen demand degradation was 78.35% after 60 min of treatment. This study proved that Fenton process can be used for pretreatment of wastewater contaminated by OTC before a biological treatment.

• Clinics in Orthopedic Surgery
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• 제10권4호
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• pp.413-419
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• 2018

Background: We aimed to examine the factors that influence synovialization of the grafted tendon after double-bundle anterior cruciate ligament (ACL) reconstruction based on second-look arthroscopic findings. Methods: Out of 205 knees that were treated between August 2008 and May 2016 with double-bundle ACL reconstruction using bio-absorbable cross-pins and Endobuttons for femoral tunnel fixation, we enrolled 65 knees (64 patients) that underwent second-look arthroscopy with hardware removal at 1 year postoperatively. Measured clinical outcomes included the Lysholm score and Tegner activity score that were evaluated preoperatively and during the final follow-up. We analyzed the relationship between synovial coverage and patient age, length of the preserved remnant tissue on the tibial side, type of bundle (anteromedial or posterolateral), type of graft (autograft or allograft), and time from injury to surgery. Results: The area of synovial coverage showed a significant statistical correlation with patient age and the length of the preserved remnant tissue on the tibial side. The average synovial coverage was significantly better for the anteromedial bundle than for the posterolateral bundle, better for the autograft than for the allograft reconstruction, and better when treated in the acute stage than in the chronic stage. However, synovialization of grafted tendon did not correlate to clinical outcomes. Conclusions: While we were able to identify several factors influencing synovialization of the grafted tendon after double-bundle ACL reconstruction, including patient age, length of preserved remnant tissue of the torn ACL, type of bundle, type of graft, and time from injury to surgery, we found no evidence that increased synovialization improves clinical outcomes at 1 year postoperatively.

• Transactions on Electrical and Electronic Materials
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• 제8권1호
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• pp.5-10
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• 2007

Using a reference slurry, ammonium dodecyl sulfate (ADS), an anionic and environmentally friendly surfactant, was investigated as an alternative to BTA for its inhibition and lubrication characteristics. Results demonstrated that the inhibition efficiency of ADS was superior to that of BTA. Coefficient of friction (COF) was the lowest when the slurry contained ADS. This suggested that adsorbed ADS on the surface provided lubricating action thereby reducing the wear between the contacting surfaces. Temperature results were consistent with the COF and removal rate data. ADS showed the lowest temperature rise again confirming the softening effect of the adsorbed surfactant layer and less energy dissipation due to friction. Spectral analysis of shear force showed that increasing the pad-wafer sliding velocity at constant wafer pressure shifted the high frequency spectral peaks to lower frequencies while increasing the variance of the frictional force. Addition of ADS reduced the fluctuating component of the shear force and the extent of the pre-existing stick-slip phenomena caused by the kinematics of the process and collision event between pad asperities with the wafer. By contrast, in the case of BTA, there were no such observed benefits but instead undesirable effects were seen at some polishing conditions. This work underscored the importance of real-time force spectroscopy in elucidating the adsorption, lubrication and inhibition of additives in slurries in CMP.

• Journal of Korean Neurosurgical Society
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• 제54권4호
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• pp.317-322
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• 2013

Objective : The surgical approach for recurrent pituitary adenoma after trans-sphenoidal approach (TSA) is challenging. We report the outcomes of the endoscopic TSA for recurrent pituitary adenoma after microscopic TSA. Methods : From February 2010 to February 2013, endoscopic TSA was performed for removal of 30 recurrent pituitary adenomas after microscopic TSA. Twenty-seven (90%) patients had a clinically non-functioning pituitary adenoma. Twenty-four (80%) patients suffered from a visual disturbance related to tumor growth. The clinical features and surgical outcomes were retrospectively analyzed for the ophthalmological, endocrinological, and oncological aspects. Results : The mean tumor volume was 11.7 $cm^3$, and gross total resection was achieved in 50% of patients. The volumetric analysis based on the postoperative MR showed that the mean extent of resection rates were 90%. Vision was improved in 19 (79%) of 24 patients with visual symptoms, and endocrinological cure was achieved in all of three functioning pituitary adenomas; however, the post-operative follow-up endocrinological examination revealed a new endocrinological deficit in one patient. Two patients required antibiotics management for post-operative meningitis. Conclusion : The endoscopic TSA can be an effective treatment option for recurrent pituitary adenoma after microscopic TSA with acceptable outcome.

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.15-22
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• 1997

The effectiveness of presteaming for improving CCA treatability on refractory Japanese larch heartwood was investigated in this study. Presteaming was effective on improving treatability, and the extent of improvement was dependent on moisture contents of wood specimen and steaming conditions. Green wood showed higher average value in both preservative retention and penetration than dry wood, and steaming under pressure conditions also had higher treatability than steaming at atmospheric conditions. The degree of improvement for treatability was increased with the extension of steaming period. Treatability of dry wood pres teamed under pressure conditions more than 6 hours and green wood for 3 hours was similar to that enhanced by conventional incising. Presteaming green wood under pressure conditions more than 6 hours was more effective than conventional incising in improvement of CCA treatability, and resultant treatability satisfied a minimum value required for CCA-treated wood for being used at the regions of hazard class H3 and H4. In addition, an improvement of treatability by presteaming was due to an increase in permeability resulted from the degradation of hemicelluloses within aspirated pit membrane and cell wall, not the removal of extractives from pit membrane. The reduction in strength, measured as longitudinal compressive strength, due to pres teaming was related with the degradation of hemicelluloses, and was increased as steaming conditions were severe. The degree of strength reduction associated with presteaming treatment to obtain required treatability could be quantified from the relatively good relation between the increase in treatability and the decrease in strength.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.219-228
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• 2021

The adoption of new technology in any organization will represent change, and such change needs user acceptance for its successful implementation. Saudi Arabian health centers are no exception; therefore, the current study will investigate the adoption of new technology, namely that of virtual reality (VR), within health centers in Saudi Arabia and specifically in Riyadh City. This study explores the current state of VR technology adoption, factors that influence such adoption, and the extent of this technology's efficiency when it is used for vaccinating children. The data were collected from two samples: workers in vaccination clinics who responded to a survey and a group of children who participated in the VR technology experiment. The current study proposed a model based on the unified theory of acceptance and use of technology 2 (UTAUT2), with the addition of two variables: personal innovativeness and satisfaction. The results indicated that the respondents' perceptions regarding the health centers' infrastructure in terms of adopting VR were moderate. Among the factors affecting VR adoption, satisfaction, personal innovativeness, and behavioral intention were identified as vastly influential factors. From the eight hypotheses, six were found to be supported, with their factors significantly influencing behavioral intention with regard to VR technology adoption. Besides, the experiment concerning the use of VR technology on children verified the technique's high efficiency in terms of providing pain management and fear removal. These findings support the continuity of VR technology use, expand its future application fields, and integrate this study into the literature on technology acceptance models for VR adoption, as limited studies have covered this topic; consequently, this will benefit future research in this field.

• 대한두경부종양학회지
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• 제36권1호
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• pp.27-31
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• 2020

The midline nasal dermoid cysts are rare congenital neoplasms, which are diagnosed frequently in childhood. Masses are often noticeable at birth gaining size over time with recurrent infections and usually arise from the nasal cavity or lower 1/3 of the nasal dorsum. CT scan as the primary investigation is helpful to determine accurately the size and extent of the lesion as well as the integrity of adjacent bony structures. MRI scan is recommended to rule out an intracranial extension or sinus tracts. Treatment of choice is the complete surgical excision preserving the cyst wall. Here in, we present an unusual case of nasofrontal dermoid cyst in a 19-year-old boy without radiographic evidence of transcranial extension. In this case, we surgically removed nasofrontal dermoid cyst via transcolumellar approach. We also corrected saddle nose deformity after mass removal. Therefore, in this case, we experienced a successful case in which the nasofrontal dermoid cyst was totally removed without facial scar and deformity.

• 한국환경복원기술학회지
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• 제13권5호
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• pp.1-11
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• 2010

It is very difficult to control the expansion of reed at a wetland ecological park due to their aggressive reproduction capability. Therefore, proper topography and wetland hydrology should be provided before the construction of a wetland ecological park. Appropriate measures should be taken at the initial stages to prevent reed expansion. Field experiments were conducted at the newly constructed wetland ecological park for 15 months to develop methods to control the reproduction and expansion of Phragmites communis. A complete shading method had the best effect on the prevention of reed reoccurrence among other methods. Complete removal of the rhizomes controlled the reed growth to a greater extent than cutting the aboveground shoots. Water-level manipulation was also better than a half-shading method for the prevention of reed reproduction. These results indicated that soil properties and edge effects can influence the reed growth. Cutting only the aboveground shoots facilitates the growth of reed. These results suggest that reed control should be implemented repeatedly and an alteration in the wetland topography and hydrology may be more effective in the long term. Combination of treatments such as water-level management with shading should be considered to control the growth of reed. Adoptive management for created or restored ecosystem might be considered for accomplishment of its original purpose.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2534-2546
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• 2023

Gas-cooled space reactor, which adopts He-Xe gas mixture as working fluid, is a better choice for megawatt power generation. In this paper, thermal-hydraulic characteristics of He-Xe gas mixture in 2×2 rod bundle wrapped with helical wires is numerically investigated. The velocity, pressure and temperature distribution of the coolant are obtained and analyzed. The results show that the existence of helical wires forms the vortexes and changes the velocity and temperature distribution. Hot spots are found at the contact corners between helical wires and fuel rods. The highest temperature of the hot spots reach 1600K, while the mainstream temperature is less than 400K. The helical wire structure increases the friction pressure drop by 20%-50%. The effect extent varies with the pitch and the number of helical wires. The helical wire structure leads to the reduction of Nusselt number. Comparing thermal-hydraulic performance ratios (THPR) of different structures, the THPR values are all less than 1. It means that gas-cooled space reactor adopting helical wires could not strengthen the core heat removal performance. This work provides the thermal-hydraulic design basis for He-Xe gas cooled space nuclear reactor.