• Journal of Korean Society for Quality Management
• /
• v.26 no.3
• /
• pp.60-70
• /
• 1998

When driving the expected loss generated by the quality deviation, Taguchi(1991b) assumed that an objective characteristic has the uniform distribution in its control limit. But it is reasonable to assume that an objective characteristic has the normal distribution than the uniform distribution. Since the triangular distribution is similar to the normal distribution and easy to handle as well, in this article, we first find the optimum measurement interval and the optimum control limit under the triangular distribution. Under the normal assumption, the modified method is compared to Taguchi's. Secondly we find the numerical value solution of the optimum measurement interval and the optimum control limit under the normal distribution.

• Proceedings of the KIEE Conference
• /
• 2000.11d
• /
• pp.632-634
• /
• 2000

The robust design of controllers to ensure gain and phase margin is can be use approximation of arctan function. In this paper, We proposed a tuning algorithm PID controllers based on specified gain and phase margin by a new approximation of arctan function. This method have linear interpolation equations of two arctan interval instead of one arctan interval of arctan(x). It is shown that the frequency response of this method was to ensure specified gain and phase margin.

• Journal of the Korean Data and Information Science Society
• /
• v.14 no.4
• /
• pp.1045-1053
• /
• 2003

Markovian EWMA control chart for simultaneously monitoring mean vector of the several correlated quality characteristics is investigated. Properties of multivariate Shewhart chart and EWMA chart are evaluated for matched FSI (fixed sampling interval) and VSI(variable sampling interval) scheme. We obtained VSI EWMA chart is more efficient than Shewhart chart for small or moderate shifts. And, we obtained stablized numerical results with Markov chain method when the number of transient state is greater than 100.

• Journal of Korean Society for Quality Management
• /
• v.36 no.1
• /
• pp.7-19
• /
• 2008

During the past two decades, a huge amount of research on adaptive control charts has been accomplished. Especially, variable sampling interval (VSI), variable sample size (VSS), and variable sample size and sampling interval (VSSI) charts have been focused by many researchers due to their simplicity and efficiency. On the other hand, the difference among notations, assumptions, methodologies may cause confusions in per forming further studies or practical implementations. This research analyses and compares diverse models so as to provide a unified view on statistical and economical characteristics. As a result, we perform comparative study on economical design models of VSI, VSS, and VSSI charts, respectively, We also present practical guidelines to utilize those adaptive control charts.

• Journal of the Korean Data and Information Science Society
• /
• v.28 no.4
• /
• pp.911-925
• /
• 2017

We investigate the properties of multivariate Shewart control charts with VSI procedure for monitoring simultaneous monitoring mean vector and covariance matrix in term of ANSW (average number of switches), probability of switch and ASI (average sampling interval), ATS (average time to signal). From examining the ANSW values, we know that it does not switch frequently. The VSI control charts are superior to the corresponding FSI control charts in terms of ATS. And, it can be also seen that the VSI procedures have substantially fewer switches for small or moderate shifts of the mean vector and variances.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.10
• /
• pp.2457-2464
• /
• 2015

Distributed Networked Control Systems (NCSs) through wireless networks have a tremendous potential to improve the efficiency of various control systems. In this paper, we define the State Update Interval (SUI) as the elapsed time between successful state vector reports derived from the NCSs. A simple expression of the SUI is derived to characterize the key interactions between the control and communication layers. This performance measure is used to formulate a novel optimization problem where the objective function is the probability to meet the SUI constraint and the decision parameter is the channel access probability. We prove the existence and uniqueness of the optimal channel access probability of the optimization problem. Furthermore, the optimal channel access probability for NCSs is lower than the channel access probability to maximize the throughput. Numerical results indicate that the improvement of the success probability to meet the SUI constraint using the optimal channel access probability increases as the number of nodes increases with respect to that using the channel access probability to maximize the throughput.

• Korean Journal of Soil Science and Fertilizer
• /
• v.47 no.3
• /
• pp.147-154
• /
• 2014

Consecutive pepper cultivation in plastic film houses may lead to salt accumulation because pepper is considered a heavy nutrient feeder. For this reason, appropriate methods of fertilizer application should be established. Thus, we investigated the effect of different intervals of side-dressing N and K fertilizer applications on soil and red pepper in a plastic film house. All the amounts of recommended compost and phosphorus fertilizer were applied as basal dressing. Cultivars of the pepper plant were Cheon-Ha-Dae-Se (CHDS) and NW-BiGaLim (NW-BGL). Nitrogen and potassium fertilizers were treated as side-dressing at different intervals, 22 times in every 10 days, 15 times in every 15 days, and 11 times in every 20 days. Soil pH decreased with decreasing the intervals of side-dressing applications, whereas electrical conductivity (EC) declined with the increasing fertilizer application intervals. In particular, EC value decreased by up to 75% with CHDS cultivar in the plot of 20 day-interval and with NW-BGL cultivar in the plot of 15 day-interval. The concentrations of available phosphorus in the soils increased with increasing the interval. The concentration of exchangeable $K^+$ increased but exchangeable $Ca^{2+}$ and $Mg^{2+}$ decreased in all the plots, except in the control plot. The concentrations of nitrogen and phosphorus in leaves of the pepper plants were lowest in the control plot. Potassium concentrations in the pepper leaves were high in the control plot and in the plots of CHDS with 10 day-interval and NW-BGL with 15 day-interval. Red pepper productivity was high in the plots of 10- and 15 day-intervals for CHDS cultivar and 15- and 20 day-intervals for NW-BGL cultivar. Therefore, the 15 day-interval of side-dressing N and K applications was considered as an appropriate method for cultivating pepper plants and protecting soil in plastic film houses.

• Journal of Bio-Environment Control
• /
• v.19 no.4
• /
• pp.234-239
• /
• 2010

The irrigation interval and time for the supply of nutrient and water to the plant is important in the aeroponic system. This study was conducted to investigate the effect of irrigation interval on the growth of Phalaenopsis hybrid seedlings in the aeroponic system. Young bare-root plants (four leaves, 16 g in fresh weight) were used for this experiment. The composition of nutrient solution was, in $me{\cdot}L^{-1}$, 9 N, 3 P, 4 K, 4 Ca and 2 Mg. The electrical conductivity (EC) and pH of nutrient solution used was $1.2\;dS{\cdot}m^{-1}$ and 5.8, respectively. Irrigation intervals were 10, 20, 30, 40, and 50 minute and each irrigation time was 10 minute. The total fresh and dry weight, the number of branched roots, and relative growth rate at the 20 and 30 min. was greater than 10, 40, 50 min. interval. Especially, the fresh weight of roots at 30 min. interval was the highest. Leaf length was the highest at 30 min. interval but there was no difference in leaf width. The amount of water consumed for a month was 0.71 L per plant and it was reduced with increasing irrigation interval. There was no difference in the amount of consumed mineral contents for 15 days except for potassium. Potassium absorbed was the highest at 30 min. irrigation interval. As a result, the optimum irrigation interval was 30 min for the production of Phalaenopsis hybrid seedlings in the aeroponic system.

• Journal of Korean Society on Water Environment
• /
• v.26 no.2
• /
• pp.297-302
• /
• 2010

It is very important to know mean and confidence interval of water-quality constituents such as BOD for water-quality control and management of rivers and reservoirs effectively. The mean and confidence interval of BOD at Anseong2 and Hwangguji3 sampling stations which are located at the border of local governments in Anseong Stream were estimated and analyzed in this paper using Bootstrap technique which is one of non-parametric statistics. The results of Bootstrap were compared with arithmetic mean, geometric mean, Biweight method mean as a point estimator and distribution mean came from the appropriate probability distribution of Log-normal. In Bootstrap technique 12 data set was randomly selected in each year and 1000 samples was produced to get parameter of population. Visual Basic for Applications (VBA) of Microsoft Excel was utilized in Bootstrap. It was revealed that the Bootstrap technique can be used to explain more rigorously and robustly the achievement or violation of BOD target concentration in Total Maximum Daily Load (TMDL).

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.4
• /
• pp.68-74
• /
• 2002

The FD process is analogous to the direct piston extrusion process where the cold feed filament acts as a piston extruding the molten filament from the heated liquefier through a nozzle. The extruded filament is deposited on top of futureless platform, where the liquefier and the nozzle move in X and Y direction control by computer based on the part geometry. After the first layer, the Z platform indexes down and the next layer get deposited on top of the first layer. the layer by layer building process introduces surface problem. This paper describes effect of slice interval of the parts built by fused deposition modelling rapid prototyping system.