The objectives of this research are to develop the welding process of copper tube for refrigeration in air conditioner by using rotation brazing table. The key design is the use of rotary head for nitrogen and rotary head for cooling water in assembly jig nitrogen discharge to prevent the internal welding soot to remove the soot that may occur during welding from piping system and to cool down the profile quickly. The result of water cooling to prevent that damage due to the heat of welding. The result from designing and creating of rotation brazing table to substitute stationary welding found that there is the reduction of machine cost by 11.61% or 46000 Baht/machine reduction of usage space 8.75 square meters or 74375 Baht increase of productivity by 93.48% reduction of nitrogen consumption by 98.20% or 2593 Baht/month reduction of support tool in production 75000 Baht per one rotation brazing table reduction of tiredness from working by 30.24% or equal to 137 manual works per day and reduction of usage of consumable material that can cause of greenhouse gas in form of trash such as cloth glove 1.40 KgCo2 per year leather glove 12.5216 KgCo2 per year nitrogen gas 0.1784 TonCo2 per year and water 0.54 KgCo2 per year. All of these can support the competition and dynamic change of industrial air conditioner in the future sustainably.

The purpose of this research is to study the construction safety system for working at height. The safety system for working at height in this research is predetermined by department of labour protection and welfare and safety and health at work promotion association (Thailand). The safety system composed of (1) safety policy (2) safety organization (3) prevention measure (4) risk analysis (5) training (6) safety inspection (7) accident report and (8) emergency planning. Since they had been used construction safety system for working at height in construction site. They have seen different number reduced from accident on site project. However the cost of construction project would have increases.For example building construction site project would taking more time to finished their project. Such as project A have costs increase 281385 baht Project B have costs increase 263648 baht and Project C have costs increase more 285413 bahtRespectively.

Currently transport has played an important role in everyday life resulting in huge traffic jams caused by big city streets and pollution problems from global warming to global temperatures are rising. Since humans are creatures that prefer comfort in all areas which contrasts with the higher temperatures of the Earth. Currently the use of air conditioning a lot. To modify the temperature is reduced in the range 2 3 to 25 degrees Celsius makes people feel comfortable. However the use of air conditioning in the car cabin cooling efficiency can be increased to a higher level than it is by cooling the refrigerant. The aim of this research is to test and compare the performance of car air conditioning systems usually equipped with a heat exchanger. Using water from the condensation of evaporator as a medium for heat transfer. By installing the equipment at the outlet of the condenser. This causes the temperature of the refrigerant is low. The pipe lengths in the equipment from the calculation of 1 .2 meters and copper lines that increases the length of the tubes was calculated to compare with a length of 1.6 meters to test the speed of the compressor 1000 1500 2000 and. 2500 rpm and a wind speed of 20 35 and 50 kilometers per hour. The results of experiment found that the temperature refrigerant equipment decreased from an average of 1.6 degrees Celsius the pipe length of 1.2 meters and 1.6 meters of pipe temperature drops 1.8 degrees average temperature attended Eva sufficiently reduced operator. It increases energy efficiency ratio averaged 6.68% of the pipe length 1.2 m and 22.24% at a length of 1.6 meters as well as to increase the coefficient of performance of the air conditioning system. 6 .6 9 % of the pipe length of 1.2 meters and a length of 1.6 meters at 22.4% with the key factor in optimizing the cars air conditioning system. Making the refrigerant from the condenser the temperature drops to pull heat out of the cabin through evaporator higher.

This thesis presents an assessment of voltage sags when faults are happened in the 115 kV transmission line of the Provincial Electricity Authority (PEA) when distributed generation (DG) is installed in the system. The computer program PSCAD/EMTDC (Power Systems Computer Aided Design / Electromagnetic Transient in DC system) version 4.2 is applied to provide electrical parameters for the modeling and simulation and to analyze the fault occurred which resulted in voltage sag. Test results from PSCAD/EMTDC show the values of voltage sag when 5 types of fault are occurred (Single Line to Ground Fault Double Line to Ground Fault Three Phase to Ground Fault Line to Fault and Three Phase Fault). For all cases the value of root mean square voltage before fault is 100% or 1.0 pu. It can be seen that for both radial line and closed circuit when DG are installed in the system the value of phase to ground RMS residual voltage and phase to phase RMS residual voltage at the bus of Bang-pa-in 2 substation are more than the values in case of the system without DG.

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.