This research proposes a hidden Markov model for detecting machines with multiple fillers producing soft drink for quality control in order to reduce defective products. The proposed model is compared with a classical generalized estimating equations model (GEE). The monthly data the number of defective products the correctness and the time spending in correction were collected from a machine in a sample factory in Pratumthanee province. The two hidden states of the fillers are workable and unworkable. The states has a logistic distribution. The results show that the correctness of the filler error occurrence does not improve the probability of being in a unworkable state neither the period of time spending on correction. The current state seems to be the same as the previous state

The aim of this research is to create the center of mass testing machine for vehicles with maximum mass 3000 kilograms. By the performance of this machine is able to determine the center of mass 3 axis by horizontal longitudinal and vertical. On the other hand the verities of mass from 50 to 250 kilograms and the several of weight distribution at horizontal and longitudinal are applied to the condition of testing for reasonable to the position of the center of gravity for vehicle. The result of research discovered to the performance of center of mass tester was activated following to test conditions. Furthermore the position of the horizontal of center of gravity depends on the weight distribution at horizontal axis and an increasing of mass under non-uniform along the longitudinal and horizontal axis. In term of the position of the longitudinal of center of gravity the weight distribution at longitudinal axis and an increasing of mass rate are points. Otherwise the weight distribution at longitudinal axis and an increasing of mass are effect to the position of the vertical of center of gravity.

Nowadays the majority of environment problem is pollution of vehicle including the noise of engine combustion. For this reason this thesis aims to compare and study the parameters which affect noise reduction on exhaust pipe. Not only reduce the noise pollution but also maintain the efficiency of the engine. These two substances must be considered. Therefore the researcher emphasized to study the parameters on 3 types of muffler with an equal volume: direct reverse and offset type of mufflers. Initiated by data collection the pressure and the velocity in muffler at the speed of engine at 1000 RPM (slow-running engine mode) and 4000 RPM (maximum running engine mode) were investigated. The data were applied into the program that called “SolidWorks” in order to study parameters. In this step the relation between the pressure and velocity of exhaust were represented. In addition the muffler models were selected to manufacture and test by the standard of The Department of Land Transport. As a result there are two major parameters of the muffler. Firstly the metamorphism of the exhaust gas flow direction pleasurably causes the lower noise at the speed of engine at 1000 RPM. Besides an increase of the flow gas distance can diminish noise at the speed of engine at 4000 RPM as well. However this muffler models were tested under the working mode of catalytic device that is standard equipment for automotive vehicles.

This research proposes reliability analysis in order to find the probability that a machine will work properly the failure rates of a machine and the factors related to the failure rates. The data were collected from 8 types of machines in an autoparts manufacturing factory. They consist of the times measured from the first day of the study until the machine produces defective product workers and production steps. The study duration is 90 days. The results show that the probability that the machine type 4 will work properly more than days is 0.40 machine type 5 more than 68 days is 0.32 machine type 6 more than 72 days is 0.31 machine type 8 more than 85 days is 0.26 machine type 9 more than 109 days is 0.80 machine type 10 at more than 52 days is 0.38 machine type 11 more than 71 days is 0.32 and the probability that the machine type 12 will work properly more than 85 days is 0.26. The failure rate of the machine type 4 at day 51 is 6.61 machine type 5 at day 68 is 1.61 machine type 6 at day 72 is 0.77 machine type 8 at day 85 is 1.26 machine type 9 at day 109 is 1.31 machine type 10 at day 52 is 0.92 machine type 11 at day 71 is 1.24 and the failure rate of the machine type 12 at day 85 is 2.15. The factors influencing on the failure rates are worker group 2 and production step 3 at the significance of 0.05.

The aim of this research is to study the varieties of weight density distribution affect to the center of mass and vehicle stability. The weight density distribution tester was designed and changed the position of mass. Base on the center of mass is main points of vehicle stability. On the other hand FMCSA standard was applied to field test for considering of the brake performance and vehicle stability. The results of research discovered to the mass distribution on horizontal plane and fixed position Y1 are absolutely influence under an increasing 50 kilograms of mass condition. For the mass distribution on longitudinal plane and fixed position Z2 and Z3 are affected to the increasing of mass 100 and 150 kilograms respectively. Otherwise under an increasing of mass 200 and 250 kilograms there is non-influence to the weight density distribution. In term of the braking performance it’s depends on the lateral mass distribution especially the center position of mass installed on longitudinal and horizontal plane and close up on the front axle (Y2). For the vehicle stability results the position (Y2) is the highest influence for yaw rate and sideslip. Otherwise the position (Y3) or the position of mass installed on longitudinal plane and nearly at the left wheel on the rear axle. Additionally wheel lock-up condition was appeared on the front axle only. Because the behavior of the weight distribution on front axle was decreased lead to mass distribution on longitudinal plane.