Thailand is a well known country where jewelry is produced to export. The process of jewelry production needs many special skills and efficient machines. Moreover the preparation of plaster is also important in producing jewelry. This requires various stages and takes more time to do. However these problems can be eliminated by knowledge in engineering. Therefore this study aimed to develop the vacuum mixer for mixing Investment for jewelry production. The vacuum mixer consists of 12 Hp 220 volts ac electric motor with the gear which has 1:40 dimension. The whole body of the vacuum mixer is made of stainless steel. The pot for mixing the Investment is 21 em. wide and 31.5 em. high. The tub at the base for placing the pot is 29 em. wide and 21 em. high. This base is equipped with a 20 m3 per hour vacuum ventilator and a vibrating motor. This vacuum mixer is operated by the electric motor which transmits power into gear. Then the gears drive the belt to make the blade stiring the Investment and water in the pot until they are well mixed together. Then the mixture is forced to the tub at the base by the valve while the air is sucked up and the mixture of the Investment is cured until all bubbles are disappeared from the mixture. After experimenting the result revealed that the use of the vacuum mixer can reduce the steps in preparing the plaster from 8 steps to 4 steps. It can also save 52% of time allotted.

โครงการนี้เป็นการพัฒนาระบบควบคุมการทำงานของเครื่องปรับอากาศ เพื่อควบคุมพลังงานไฟฟ้า ที่จ่ายให้กับเครื่องปรับอากาศขนาดเล็ก ที่ใช้งานทั่วๆไป โดยใช้วิธีการควบคุมอุปกรณ์กำลัง โดยการปรับความกว้างของสัญญาณควบคุมที่ผสมกับสัญญาณพาหะ (Pulse Width Modulation: PWM) วงจรควบคุมใช้ตัวควบคุมขนาดเล็ก (Micro Controller)

The purposes oj the research were to create computer assisted instruction for Jewelry Finishing Subject to find out the efficiency validation of computer assisted instruction based on the standard of 90/90 and to analyse the students leaming achievement after using the computer assisted instruction. The subjects in tile study were 17 first-year diploma engineering students enrolling at Rajamangala University of Technology Phra Nakhon. The researcher made the experiment by having the students pretest. Then they studied by using the computer assisted instruction focused on practicing basic turning. After the students had studied and had posttest the efficiency of the computer assisted instruction was calculated as well as the learning achievement was analysed. The research result revealed that the efficiency of the computer assisted instruction was at the standard of 90 1 90. Moreover the learning achievement after using the computer assisted instruction was different at the significant level of 0.05.

The purposes of the research were to create and efficiency validation of computer assisted for the courses of practiced to make body of ornaments based standard 90/90 and analyse the leaning achievement of the student after by using computer assisted instruction. The subjects in the study were 17 first year diploma students enrolled in Rajamangala University of Technology Phra Nakhon. The Researcher using the experiment by let the students do until test before class And then study by using computer assisted instruction focused on practiced to basic turning. After that let students do the unit test again at the class and calculate to find out the efficiency of the computer assisted instruction and analyse the leaning achievement of students after study. The research result revealed that the efficiency of the computer assisted Instruction was efficient in standard 90/90 Moreover after learning achievement At significant level of 0.05

The purposes of the research were to create and find efficiency validation ofcomputer assisted instruction focused on the mold plastic injection making kind two plate for the standard 90/90 and analyze the students learning achievement after using computer assisted instruction. The samples were the 15 first year diploma tool & die students Rajamangala Institute of Technology North Bangkok Campus. The researcher experimented by using pretest and then using the computer assisted instruction focus on the mold plastic injection making kind two plate mold base make mold and adjust next the students did the posttest. After that the researcher calculated to find the computer assisted instruction efficiency and analyzed the students learning achievement after studying. The result revealed that the computer assisted instruction efficiency was efficient for standard 90/90. And after studying by using computer assisted instruction the students learning achievement increased significantly at 0.05.