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Abdul Rahman 서울대학교 교육연구소 2019 Asia Pacific Education Review Vol.20 No.4
This paper argues that the professional learning of teachers is shaped and conditioned by the circumstances, arrangements, and specificity of teacher professional development (TPD) learning activities or programs of a particular context or system. Specifically, this research reveals how practices of TPD programs in Indonesia influence teachers’ professional learning perceptions and practices. This research draws on a larger multiple-case-study research that looks into the influences, and possible interplay, of teacher characteristics, TPD learning activities, and schools on teacher professional learning in Indonesia. This paper reports findings of the research question that investigates teachers’ perception towards TPD learning activities that they have been involved in during the 18-month period prior to participating in the research project. The results show that teachers participate in various forms/types of TPD learning activities that can be (1) formal, designed, and mandated by parties external to teachers; (2) informal, voluntary, and incidental, arising from teachers’ daily practices and interpersonal communication and interaction with others; and (3) can also be either personal or collaborative as a professional learning undertaking. “Restrictive” and “facilitative” TPD are the two conflicting themes that represent the influences of practices of TPD programs in Indonesia.
Abdulrahman Al-Ahmari,Mohammad Ashfaq,Abdullah Alfaify,Basem Abdo,Abdulrahman Alomar,Abdelnaser Dawud 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1
Electron beam melting (EBM) has been found to be a promising technology for producing complex shaped parts from gamma titaniumaluminide alloys (γ-TiAl). The parts produced by this process are projected to have dimensions very close to the desired final shapes. However, the surface roughness of the parts produced by EBM is excessively rough. In many applications, it is necessary to improve thequality of manufactured parts using a convenient post process. This paper determines process parameters of end milling when it is usedas a post process for the parts produced by EBM. Design of experiments has been used to study the effect of the selected input parametersof end milling (spindle speed, feed rate, depth of cut and coolant type) on the surface roughness of γ-TiAl parts. Response surface methodologyis used to develop a predictive model for surface roughness. Effects of the selected milling process are investigated. This paperalso optimizes the selected process parameters to minimize the value of the obtained surface roughness.
Abdulrahman Y. Almansouri,Mohammed E. Abdulfatah,Omar H. Baaqil,Alaa A. Bakheet,Sarah A. Turki,Mamdouh M. Kotb,Alaa Althubaiti,Majed M. Almaghrabi,Abdulrahman M. Althubaiti,Badr M. Madani,Ali S. M. Ja 대한골대사학회 2016 대한골대사학회지 Vol.23 No.1
Background: The aim of the study was to compare serum sclerostin levels in human immunodeficiency virus (HIV)-infected patients and healthy controls, and to evaluate their relationship with bone turnover markers (BTM) and bone mineral density (BMD). Methods: We prospectively studied 33 HIV treatment-naive patients and 63 healthy individuals; match ed for age and sex. Serum sclerostin levels, BTM, BMD were measured. Viral load and cluster of differentiation 4 (CD4) levels were also assessed in HIV-infected patients. Results: The mean±standard deviation (SD) age of sample was 37.6±10.3 years (range, 19 to 59 years). Of the 96 subjects, 58 (60.4%) were male and 38 (39.6%) were female. Infection with HIV is associated with significant reduction in serum sclerostin levels (HIV-infected: 39.4±28.3 vs. non HIV: 76.6±15.7 pmol/L; P<0.001) and a decrease in BMD at femoral neck and lumbar spine compared to healthy controls. Sclerostin however was not correlated with BMD and was not related to age, generally a strong correlation. There were no significant correlations between sclerostin and BTM (P>0.05). Conclusions: These findings suggest that untreated HIV and the resulting immune deficiency and/or systemic inflammation could be an important regulator of serum sclerostin in this population.
Abdulrahman S.M. Alqadami,Mohd Aminudin Jamlos,Mohd Aminudin Jamlos 한국물리학회 2019 Current Applied Physics Vol.19 No.11
The recently introduced polymeric nanocomposites substrate layer technology is used in the design of a flexible antenna array for wearable applications. This new technology allows a considerable widening of the bandwidth of classical microstrip topologies. This means that a relatively wide band can be combined with a full ground plane in a very simple structure, which is an ideal combination in wearable applications. The wideband and flexible features enabled the antenna to mitigate body-detuning effects. The proposed antenna prototype consists of a 2×2 array of rectangular patch elements with dimensions of 70×70×4.2mm3. The measurements are performed in free space, and on-body under bent conditions. The antenna working within the frequency band of 5 GHz–8.2 GHz, with a fractional impedance (FBW) bandwidth of 50.34%. The antenna demonstrates a maximum radiation efficiency of 60%, and 9.8 dB of realized gain. Since this antenna is intended for on body-centric wireless communication application, the specific absorption rate is evaluated when the antenna is placed on the right arm of a realistic human phantom. The performances and features of the proposed antenna paved the way for off-body connections in a WBAN and wearable applications including WiFi, telemedicine and Vehicle-to- Everything (V2X).
Sensitivity studies in spent fuel pool criticality safety analysis for APR-1400 nuclear power plants
Abdulrahman S. Al Awad,Abdalla Habashy,Walid A. Metwally 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.5
A criticality safety analysis was performed for the APR-1400 spent fuel pool region-II to ensure the safestorage of spent fuel, with credit taken for depletion and in-rack neutron absorbers (Metamic panels). PLUS7 fuel assembly was modeled using TRITON-NEWT of SCALE-6.1. The burnup-dependent crosssectionlibrary was generated under limiting core-operating conditions with 5%-w U-235 initialenrichment. MCNP5 was used to evaluate the neutron multiplication factor in an infinite array of rackcells with the axially nonuniformly burnt PLUS7 assemblies under normal, abnormal, and accidentconditions; including all biases and uncertainties. The main purpose of this study is to investigatereactivity variations due to the critical depletion and reactor operation parameters. The approach, assumptions,and modeling methods were verified by analyzing the contents of the most important fissileand the associated reactivity effects. The Nuclear Regulatory Commission (NRC) guidance on k-eff beingless than 1.0 for spent fuel pools filled with unborated water was the main criterion used in this study. Itwas found that assemblies with 49.0 GWd/MTU and 5.0 w/o U-235 initial enrichment loaded in Region-IIsatisfy this criterion. Moreover, it was found that the end effect resulted in a positive bias, thus ensuringits consideration
Influence of operator's experience level on lifespan of the WaveOne Primary file in extracted teeth
Abdulrahman Mohammed Saleh,,Saeid Tavanafar,,Pouyan Vakili-Gilani,Noor Jamal Al Sammerraie,Faahim Rashid 대한치과보존학회 2013 Restorative Dentistry & Endodontics Vol.38 No.4
Objectives: The aim of this study was to assess the influence of operator experiencelevel on the lifespan of the WaveOne Primary file (Dentsply Maillefer, Ballaigues,Switzerland) in extracted teeth. Materials and Methods: Moderately curved canals ofextracted maxillary and mandibular molars were randomly distributed into 2 groups:experienced and inexperienced operators. Ten files were allocated to each group (n =10). Each canal was prepared until the working length was reached, and the same filewas used to prepare additional canals until it separated. The number of canals preparedbefore file separation was recorded. The fragment length of each file was measured,and the location of the fragment in the canal was determined. Data were statisticallyanalysed using the independent 2-sample t-test. Results: The 2 operators prepared atotal of 324 moderately curved canals of maxillary and mandibular molars. There wasno significant intergroup difference in the mean number of canals prepared (p = 0.27). The average lifespan of the WaveOne Primary file was 17.1 and 15.3 canals, and thelongest lifespan was 25 and 20 canals, when used by experienced and inexperiencedoperators, respectively. There were no statistically significant intergroup differencesin separated fragment length and location. Conclusions: Within the limitations ofthis study, operator experience level appears to have no effect on the lifespan of theWaveOne Primary file in preparation of moderately curved canals. Single teeth withmultiple canals can be prepared safely even by a novice operator by using a single file.