 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : A Study of Optimal Burn-In Time to Minimize Cost for a Series System Sold Under Warranty) ผู้เขียน: Wimonmas Lengbamrung, Adisak Pongpullponsak สื่อสิ่งพิมพ์:pdf AbstractThis research aimed to study a series system undergoing a two-level burn-in procedure. A cost model was developed to calculate the optimal burn-in time and minimal total cost of products. Then the system cost model was used to analyze the effect of components and the systems that undergo a burn-in process. The numerical examples illustrated the failure times of products followed a mixed exponential distribution. The results indicated that the optimal burn-in time could minimize the total mean cost and maximize the system reliability based on nonlinear programming. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Minimizing The Cost of an Integrated Model by EWMA Control Chart) ผู้เขียน:Pramote Charongrattanasakul, Adisak Pongpullponsak สื่อสิ่งพิมพ์:pdf AbstractTwo key tools for process management are statistical process control (SPC) and maintenance management (MM). An economic model can be created when they are coordinated. This paper studied the exponentially weighted moving average (EWMA) control chart of SPC and planned maintenance, as well comparing the optimal values of an X-bar control chart and an EWMA control chart. A mathematical model was developed to analyze the cost computed from the EWMA control chart. This was used to find the optimal values of variable parameters (n*,h*,L*,k*) that minimized the hourly cost. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Study of Parameters Affecting Drying Kinetics and Quality of Corns) ผู้เขียน:Somboon Wetchacama, Somchart Soponronnarit, Somkiat Prachayawarakorn, Adisak Pongpullponsak, Wuttitat Tuntiwetsa, Suprarat Kositcharoeankul สื่อสิ่งพิมพ์:pdf AbstractThe objectives of this research are to investigate factors affecting on drying rate of high moisture corn at high temperature with fluidisation technique and to develop a mathematical model for predicting drying rate. There were three following steps of drying process: 1) rapid drying using fluidised bed dryer at inlet drying air temperature of 130-170?C, 2) corn tempered for period of 40-180 minutes under the same temperature as drying from the step 1 and 3) drying with ambient air. Drying kinetic shows the inlet air temperature and the specific airflow rate significantly affecting the drying rate. Amongst three semiempirical drying equations (Wang and Singh, Page and Lewis), Page’s equation provides the best prediction. This study also aims to study the quality of corn dried in each step. Corn qualities in terms of aflatoxin content, percentages of breakage and stress crack, and colour change have been considered. Experimental results show that aflatoxin content in dried corn does not change. Breakage and cracking depend strongly on final moisture content and are relatively dependent to temperature. Tempering provides the improvement of colour while inlet air temperature has no effect. |