• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
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• pp.24-32
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• 2004

The characteristics of heat transfer from horizontal cylinder immersed in both a riser and downcomer of a circulating fluidized beds were investigated experimentally under different values of solids mass flux, superficial air velocity, particle size diameter, and different bed materials. The test results indicated that local heat transfer coefficients in both riser and downcomer are strongly influenced by angular position, and mass flux, as well as by particle size and bed materials. The local heat transfer coefficients around a circumference of the cylinder inside a riser and downcomer of a CFB exhibited a general tendency to increase with decreasing particle size and increasing solids mass flux and vary with different bed materials. Also the averaged heat transfer coefficient calculated from local heat transfer coefficient exhibited the same trend as a local i.e increase with decrease particle size and increasing solids mass flux and vary with varying bed materials. The general trend for a riser local heat transfer coefficient is decrease with increase angle until ${\Phi}$ = 0.5-0.6 (Where at angle =180$^{\circ}$ ${\Phi}$ =1). Also the general trend for a local heat transfer coefficient in downcomer is to increase with increase the angle until ${\Phi}$= ${\theta}/{\Pi}$ = 0.3-0.5 (Where at angle =180$^{\circ}$ ${\Phi}$ =1). Comparison the results of the heat transfer in the riser and downcomer of a circulating fluidized beds shows that they have approximately the same trend but the values of heat transfer coefficients in riser is higher than in downcomer.

• Journal of Advanced Marine Engineering and Technology
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• 제35권7호
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• pp.938-945
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• 2011

Unsteady flow simulations through a transonic turbine vane were carried out for an isentropic Mach number of 1.02 and a Reynolds number of $10^6$. The main objective of the study is to investigate the effect of unsteadiness due to vortex shedding on the flow in transonic regime. The steady and the time-averaged unsteady results by employing three different turbulence models: shear stress transport (SST), k-${\omega}$, and ${\omega}$ Reynolds stress models were compared. The comparisons were emphasized on the isentropic Mach number along the blade and total pressure loss at the cascade exit. The results showed that both steady and unsteady calculations have good agreement with experimental data along the blade surface. However, at cascade exit, the unsteady calculations have much better agreement with experimental data than steady calculations. Based on these, we conclude that the unsteady flow calculations are essential for these types of problems.

• 한국항공운항학회지
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• 제15권2호
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• pp.25-31
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• 2007

The ADS-B test is a program that is examining the use of ADS-B, especially CDTI for aircraft surveillance in Korea. The ADS-B project is to provide operational benefits to Air Traffic Controllers in the selected area and provide first operational experience of ADS-B in ATCS environment of South Korea. For these objectives, the ground station has installed in Tae-An airport, Participation in the Ground Test has been limited to 4 Aircraft of Hanseo University which are installed ADS-B equipment. Ground test is a test that is examining on the movement area of Tae-An Airport on the assumption that the visibility is below weather minia of the airport. This test have been experimented as pre-arranged scenarios. In view of the results achieved, it has shown that the volume of voice communication between controller and pilot are remarkably reduced. Additionally, as both pilots and air traffic controllers are able to see the positions of traffic in the vicinity of the aircraft, the test has demonstrated that it is possible for ADS-B not only to decline the controller's workload, but also to enhance pilot situational awareness in the near future.

• Structural Engineering and Mechanics
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• 제34권6호
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• pp.755-778
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• 2010

Near-fault ground motion with directivity or fling effects is significantly influenced by the rupture mechanism and substantially different from ordinary records. This class of ground motion has large amplitude and long period, exhibits unusual response spectra shapes, possesses high PGV/PGA and PGD/PGA ratios and is best characterized in the velocity and the displacement time-histories. Such ground motion is also characterized by its energy being contained in a single or very few pulses, thus capable of causing severe damage to the structures. This paper investigates the characteristics of near-fault pulse-like ground motions and their implications on the structural responses using new proposed measures, such as, the effective frequency range, the energy rate (in time and frequency domains) and the damage indices. The paper develops also simple mathematical expressions for modeling this class of ground motion and the associated structural responses, thus eliminating numerical integration of the equations of motion. An optimization technique is also developed by using energy concepts and damage indices for modeling this class of ground motion for inelastic structures at sites having limited earthquake data.

• Imaging Science in Dentistry
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• 제43권1호
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• pp.17-23
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• 2013

Purpose: The purpose of this study was to assess cone-beam computed (CBCT) sialography imaging in the detection of different changes associated with lesions of salivary glands. Materials and Methods: This study consisted of 8 cases with signs and symptoms from salivary gland lesions. Conventional sialography using digital panoramic and lateral oblique radiographs and CBCT sialography were performed for each subject. The radiographs were evaluated by 3 radiologists independently of each other. The results were compared between conventional sialography and CBCT sialography in the evaluation of various lesions associated with the salivary glands. Results: There was an agreement between the radiologists in interpreting the lesions that affected salivary glands with both techniques. The detection of the presence of stones or filling defects, stenosis, ductal evagination, dilatation, and space occupying lesions was 83% for conventional sialography compared with CBCT sialography. CBCT sialography was superior to conventional sialography in revealing stones, stenosis, and strictures, especially in the second and third order branches. Conclusion: It would be advisable to perform CBCT sialography in cases of obstructive salivary gland diseases for better demonstration of the ductal system of the gland.

• Earthquakes and Structures
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• 제1권2호
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• pp.147-162
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• 2010

The ground acceleration measured at a point on the earth's surface is composed of several waves that have different phase velocities, arrival times, amplitudes, and frequency contents. For instance, body waves contain primary and secondary waves that have high frequency content and reach the site first. Surface waves are composed of Rayleigh and Love waves that have lower phase velocity, lower frequency content and reach the site next. Some of these waves could be of more damage to the structure depending on their frequency content and associated amplitude. This paper models critical earthquake loads for single-degree-of-freedom (SDOF) inelastic structures considering evolution of the seismic waves in time and frequency. The ground acceleration is represented as combination of seismic waves with different characteristics. Each seismic wave represents the energy of the ground motion in certain frequency band and time interval. The amplitudes and phase angles of these waves are optimized to produce the highest damage in the structure subject to explicit constraints on the energy and the peak ground acceleration and implicit constraints on the frequency content and the arrival time of the seismic waves. The material nonlinearity is modeled using bilinear inelastic law. The study explores also the influence of the properties of the seismic waves on the energy demand and damage state of the structure. Numerical illustrations on modeling critical earthquake excitations for one-storey inelastic frame structures are provided.

• The Korean Journal of Pain
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• 제34권1호
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• pp.114-123
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• 2021

Background: Evaluation of the effectiveness of caudal epidural injection on pain, spine mobility, disease activity, and activity of daily living in axial spondyloarthritis (SpA) patients. Methods: A total sample of 47 patients were registered in this study. They were randomly assigned into 2 groups; Group I received caudal epidural injections, ultrasound-guided, with 1% lidocaine hydrochloride mixed with triamcinolone, whereas Group II did not receive any injections. All participants fulfilled the ASAS criteria for axial SpA. Outcome measures were as follows: visual analogue scale, Oswestry disability index (ODI), modified Schober test, lateral lumbar flexion, and Ankylosing Spondylitis Disease Activity Score (ASDAS) with assessment at baseline, 2 weeks, and 8 weeks post-treatment. This clinical trial was registered on clinicaltrials.gov under the number NCT04143165. Results: There was a significant difference between both groups regarding pain, ODI, spine mobility and ASDAS scores in favor of group I. This effect was at its maximum after 2 weeks. Despite the decline of this effect after 2 months, the difference between the groups remained significant. Higher disease activity, younger age, and shorter disease duration were associated with better outcomes. Conclusions: Epidural injection of lidocaine and triamcinolone is a cost effective and a practical technique for controlling pain, as well as improving the function of the spine and disease activity scores in axial SpA patients with acceptable complications and relatively sustained effect.

• International Journal of Computer Science & Network Security
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• 제22권11호
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• pp.1-10
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• 2022

This study aims to build a model is capable of classifying the categories of hadith, according to the reliability of hadith' narrators (sahih, hassan, da'if, maudu) and according to what was attributed to the Prophet Muhammad (saying, doing, describing, reporting ) using the supervised learning algorithms, with a view to discover a relationship between these classifications, based on the outputs of this model, which might be useful to avoid the controversy and useless debate on automatic classifications of hadith, using some of the statistical methods such as chi-square, information gain and association rules. The experimental results showed that there is a relation between these classifications, most of Sahih hadiths are belong to saying class, and most of maudu hadiths are belong to reporting class. Also the best classifier had given high accuracy was MultinomialNB, it achieved higher accuracy reached up to 0.9708 %, for his ability to process high dimensional problems and identifying the most important features that are relevant to target data in training stage. Followed by LinearSVC classifier, reached up to 0.9655, and finally, KNeighborsClassifier reached up to 0.9644.

• Imaging Science in Dentistry
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• 제42권1호
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• pp.5-12
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• 2012

Purpose : This study was performed to evaluate possible variations in maxillary and mandibular bone texture of normal population using the fractal analysis, particles count, and area fraction in intraoral radiographs. Materials and Methods : Periapical radiographs of patients who had full mouth intraoral radiographs were collected. Regions of interest ($100{\times}100$ pixels) were located between the teeth of the maxillary anterior, premolar, and molar area, as well as the mandibular anterior, premolar, and molar areas. The fractal dimension (FD) was calculated by using the box counting method. The particle count (PC) and area fraction (AF) analyses were also performed. Results : There was no significant difference in the FD values among the different groups of age, gender, upper, and lower jaws. The mean FD value was $1.49{\pm}0.01$. The mean PC ranged from 44 to 54, and the mean AF ranged from 10.92 to 11.85. The values of FD, PC, and AF were significantly correlated with each other except for the upper molar area. Conclusion : According to the results, patients with normal trabecular pattern showed a FD of approximately 1.5. Based on these results, further investigation would be recommended if the FD value of patient significantly differenct from this number, since the alteration of this value indicates microstructural modification of trabecular pattern of the jaws. Additionally, with periapical radiographs, simple and cost-effective, PC and AF could be used to assess the deviation from the normal.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제23권3호
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• pp.266-275
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• 2020

Purpose: The outcome predictors of Kasai portoenterostomy (KPE) for biliary atresia (BA) are controversial. This study aimed to identify possible short-term outcome predictors of KPE for BA in infants. Methods: This retrospective study included infants with BA who underwent KPE between January 2015 and December 2017 and were followed up for at least 6 months after surgery at the Pediatric Hepatology Unit, Cairo University Pediatric Hospital, Egypt. The short-term outcome was jaundice clearance within 6 months following surgery. All data were compared between the jaundice free group and those with persistent jaundice to identify the predictors of jaundice clearance. Results: The study included 75 infants. The mean age at the time of surgery was 82.43±22.77 days (range, 37-150 days), and 28 (37.3%) infants cleared their jaundice within 6 months postoperative. Age at surgery did not significantly affect the outcome (p=0.518). Infants with persistent jaundice had significantly higher pre-operative levels of aspartate aminotransferase (AST) than those who were jaundice free (p=0.041). Receiver operating characteristic curve analysis showed that preoperative AST ≤180 IU/L was predictive of a successful KPE, with sensitivity 74.5% and specificity 60.7%. Infants with bile plugs in liver biopsy had a 6-fold higher risk of persistent jaundice than those without bile plugs (95% confidence interval: 1.59-20.75, p=0.008). Conclusion: Jaundice clearance after KPE for BA can be predicted using preoperative AST and presence of bile plugs in liver biopsy.