จำนวน Repository ( 1574 )

การใช้ประโยชน์และความคุ้มค่าของระบบสารสนเทศกิจกรรมนักศึกษา
การใช้ประโยชน์และความคุ้มค่าของระบบสารสนเทศกิจกรรมนักศึกษา

The purpose of this research is to study the Rajamangala University of Technology Phra Nakhon student activities information system usage and payoff if it meets the requirements of the university in order to keep track of the students extra curriculum activities and to study the user satisfaction usage and payoff of the system. 385 samples were systematically randomly selected among 10153 students studying in the undergraduate class year 1 to year 3 and the personnel working in all Faculties of the university at the 95% confidence level. The study found the following results: The majority of the respondents mainly were female 54.5 percent 96.4 percent were students studying in year 1 41.3 percent and from Business Administration Faculty 36.9 percent. Overall satisfaction toward the student activities information system was at a high level with an average of 3.66. Overall usage of the student activities information system was at a high level with an average of 3.74 and overall payoff of the student activities information system was at a high level with an average of 3.77. The hypothesis testing showed that different personal factors including gender occupation/status class and faculty did not varied the satisfaction toward the student activities information system statistically significant at the .05 level. Different personal factors including gender occupation/status class and faculty did not varied the usage of the student activities information system statistically significant at the .05 level. Different personal factors including gender occupation/status class and faculty did not varied the payoff of the student activities information system statistically significant at the .05 level. Satisfaction toward the student activities information system including system quality information quality and service quality is positively related to the usage of the student activities information system statistically significant at the .05 level and the student activities information system usage is positively related to the student activities information system payoff statistically significant at the .05 level.

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การศึกษาแก้วเซรามิกชีวภาพที่ประกอบด้วยผลึกเฟอร์โรแมกเนติกระดับนาโนจากระบบที่มีและไม่มีซิลิกาเป็นองค์ประกอบด้วยวิธีอินคอเปอเรชัน
การศึกษาแก้วเซรามิกชีวภาพที่ประกอบด้วยผลึกเฟอร์โรแมกเนติกระดับนาโนจากระบบที่มีและไม่มีซิลิกาเป็นองค์ประกอบด้วยวิธีอินคอเปอเรชัน

The aim of this work was to study the magnetic properties of magnetic glass-ceramics with composition system SiO2-CaO-Na2O-P2O5-BaO-Fe2O3. The magnetic glass–ceramics were prepared by conventional melting at 1300oC for 2 h of the coprecipitation derived starting products and heat treated at different temperatures. The structure and microstructure of the samples were characterized by X-ray diffraction energy dispersive X-ray analysis (EDXA) and scanning electron microscopy. The magnetic measurement showed that the samples which contained barium ferrite exhibited magnetic behavior which is similar to soft magnetic materials. Finally the samples were soaked in simulated body fluid (SBF) for 14 days. The apatite was found to form on the surface layer of glass-ceramics and it increases with the barium ferrite content was increased.

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การปรับปรุงความเหนียวและความทนแรงกระแทกของพอลิแลกติกแอซิดโดยการใช้น้ำมันถั่วเหลืองที่ผ่านการดัดแปรและเส้นใยธรรมชาติ
การปรับปรุงความเหนียวและความทนแรงกระแทกของพอลิแลกติกแอซิดโดยการใช้น้ำมันถั่วเหลืองที่ผ่านการดัดแปรและเส้นใยธรรมชาติ

This research work was to study the improvement of toughness and impact resistance of polylactic acid (PLA) with modified soybean oil (MSBO) and palm fiber (PF). The detail of this work was divided into three parts. The first was to find the suitable condition for modification of soybean oil with ozonolysis. The second and last parts were to study the effects of MSBO and PF contents on the properties of PLA respectively. For oil modification the reaction times were varied from 0 to 3 hours and the chemical changes in molecules of soybean oil were investigated by Nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies. The result suggested that the most suitable condition for ozonolysis reaction was 2 hours considering the decrease in double bond between carbon atoms and the increase in hydroxyl group into molecular structure of MSBO. For the effect of MSBO content on mechanical properties it was evaluated by tensile and impact testing. Differential scanning calorimeter (DSC) and scanning electron microscope (SEM) were used for thermal and morphology analyses. The result showed that elongation at break and impact strength of modified PLA by MSBO increased about 89 and 25 % compared to those of neat PLA respectively. MSBO act as the efficient plasticizer for PLA considering the conversion of fracture behavior from brittle to ductile good dispersions of MSBO droplets in PLA and the decrease of glass transition temperature (Tg) with addition of MSBO. The addition of PF improved the impact strength of modified PLA. Strong interfacial bonding between PLA and PF indicated MSBO being both coupling agent for PLA and natural fiber and plasticizer for PLA. For migration test it was found that contents of released heavy metal and migrated chemical from specimens of PLA and PLA/PF composite were under the criteria according to Notification of the Ministry of Public Health (No. 295) B.E. 2548.

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การเตรียมและศึกษาสมบัติทางโครงสร้างและแม่เหล็กของอนุภาคคอมโพสิตระดับนาโนเมตรของไฮดรอกซีอะพาไทต์และซิงก์เฟอไรท์ เพื่อประยุกต์ใช้ในการรักษามะเร็งในอนาคต
การเตรียมและศึกษาสมบัติทางโครงสร้างและแม่เหล็กของอนุภาคคอมโพสิตระดับนาโนเมตรของไฮดรอกซีอะพาไทต์และซิงก์เฟอไรท์ เพื่อประยุกต์ใช้ในการรักษามะเร็งในอนาคต

A promising composite of zinc ferrite (ZnFe2O4) and bioactive hydroxyapatite (Ca10(PO4)6(OH)2 ;HAp) has expected to potential for future bone reinforcing formation. In present study zinc ferrite and hydroxyapatite composite was prepared by solid state reaction route for easier control of structural and magnetic characteristics and with low cost. Hydroxyapatite powder was synthesized by precipitation method from chicken eggshell. Mixed powders with varying ZnFe2O4/HAp weight ratios from 2-10 wt% were milled together and uniaxially pressed and then sintered at 1200 oC for 3 hours. The XRD results showing no other phases of composite with only HAp and ZnFe2O4 phases were identified indicating high stability of HAp property. Phase fractions of ZnFe2O4 were found to increase from 10.8 to 18.73 wt% with increasing content of ZnFe2O4. FT-IR results of ZnFe2O4/HAp composite were only revealed vibration bands of standard HAp phase. This may due to the overlapping of the ZnFe2O4 vibrational bands with HAp bands. However their intense variations observed in HAp vibrational bands indicated the interaction between ZnFe2O4 and HAp. The surface morphology of these ZnFe2O4/HAp composite exhibited primary grain in nano scale with enhanced pore structure and Interconnectivity when ZnFe2O4 weight ratios increased; indicating high surface area for cell attachment and better good cell growth and differentiation. The higher saturation magnetization as well as higher super paramagnetic behavior could be easily altered by increasing ZnFe2O4 content in the composite.

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การศึกษาค่าความถูกต้องของการวัดความต้านทานด้วยดิจิทัลมัลติมิเตอร์
การศึกษาค่าความถูกต้องของการวัดความต้านทานด้วยดิจิทัลมัลติมิเตอร์

In general the measured resistance with a digital multimeter. Users tend to be measured and then displayed on the screen to the user regardless of the value that is accurate or not. The value displayed on screen digital multimeter may be incorrect. As a result from wires access point measurement and other factor that affect to the value of measurement. Thus the study of factors that affect the measurement to get the accurate and more precise and also can be used in the operations. According to international standard quality system requirements for ISO are clearly on the meter or the measuring device must be calibrated and in the certificate specifies the gain calibration and the uncertainty of measurement. Therefore it is necessary to evaluate the uncertainty of measurement to comply with the standard splash. This thesis presents a study of the effect to the measurement resistance in 0.01 ohm to 100 mega-ohm by direct measurement for 2wire & 4wire Loading effect Using different kinds of conductors Thermal EMF and the stability of the resistor. Include the statistical analysis was used to estimate the uncertainty. From this study can be applied to measure the resistance in a variety of accurately and precisely.

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