• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.27 no.4
• /
• pp.125-132
• /
• 2004

Computer simulation is widely known as a very powerful and practical tool to understand behaviors of considered systems and evaluate design alternatives. However, to use simulation technologies, one should acquire simulation languages, statistics, etc. Also, lots of resources such as time and money are necessary to develop models and analyze statistical data. These obstacles prevent one from adopting simulation tools easily. This paper presents practical guidelines for successful application of simulation. Firstly, we propose how to acquire simulation tools to help one who is going to use simulation techniques. Next guidelines are for introducing simulation software set including simulation and support softwares. Lastly, guidelines for simulation project management are presented.

• IE interfaces
• /
• v.20 no.1
• /
• pp.1-10
• /
• 2007

The main purpose of this research is to find out whether curriculums of industrial engineering (IE) departments meet the demand of IE graduates working in various fields. The research was conducted as an online questionnaire survey selecting IE Graduates working in industries as practising engineers. 1,324 participants were validated among 1,477 participants. 13 fields were selected and used in the survey. Those were; 1) Mathematical statistics, 2) Computer, 3) Purchase, 4) Production system, 5) Logistics, 6) Marketing, 7) Monetary, 8) Experiment methods, 9) Operations Research (OR), 10) Human Factors, 11) Quality, 12) Engineering management, and 13) Information systems. Using the 5-scale Likert rating, each education subject was assessed both in terms of its usefulness in practices and the amount it being taught in school. As a result, courses such as motion/time study, linear programming that IE has traditionally focused showed less usefulness in practices while it is taught in relatively large amount in schools. However, courses such as 6 sigma, CRM which are closely related to industrial practices showed high usefulness in practices compared with low degree of teaching in school. This was the first ever large scalesurvey conducted for IE graduates in Korea. The result of survey displayed many helpful information on current status and future direction of IE education in Korea.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.2
• /
• pp.687-701
• /
• 2020

In the production of industrial fabric, it needs automatic real-time system to detect defects on the fabric for assuring the defect-free products flow to the market. At present, many visual-based methods are designed for detecting the fabric defects, but they usually lead to high false alarm. Base on this reason, we propose a Sobel operator combined with patch statistics (SOPS) algorithm for defects detection. First, we describe the defect detection model. mean filter is applied to preprocess the acquired image. Then, Sobel operator (SO) is applied to deal with the defect image, and we can get a coarse binary image. Finally, the binary image can be divided into many patches. For a given patch, a threshold is used to decide whether the patch is defect-free or not. Finally, a new image will be reconstructed, and we did a loop for the reconstructed image to suppress defects noise. Experiments show that the proposed SOPS algorithm is effective.

• The Korean Journal of Applied Statistics
• /
• v.19 no.2
• /
• pp.217-230
• /
• 2006

e discuss proper confidence intervals for interval estimation of a low binomial proportion. A large sample surveys are practically executed to find rates of rare diseases, specified industrial disaster, and parasitic infection. Under the conditions of 0 < p ${\leq}$ 0.1 and large n, we compared 6 confidence intervals with mean coverage probability, root mean square error and mean expected widths to search a good one for interval estimation of population proportion p. As a result of comparisons, Mid-p confidence interval is best and AC, score and Jeffreys confidence intervals are next.

• The Korean Journal of Applied Statistics
• /
• v.31 no.2
• /
• pp.189-204
• /
• 2018

This study is on forecasting the electricity consumption of an industrial manufacturing building called GGM from January 2014 to April 2017. We fitted models using SARIMA, SARIMA + GARCH, Holt-Winters method and ARIMA with Fourier transformation. We also forecasted electricity consumption for one month ahead and compared the predicted root mean square error as well as the predicted error rate of each model. The electricity consumption of GGM fluctuates weekly and annually; therefore, SARIMA + GARCH model considering both volatility and seasonality, shows the best fit and prediction.

• International Journal of Reliability and Applications
• /
• v.5 no.4
• /
• pp.129-145
• /
• 2004

We use a novel, forced censoring technique that closer fits the lower tails of strenth distributions to better estimate extremly smaller percentiles for measuring progress in continuous improvement initiatives. These percentiles are of greater interest for companies, government oversight organizations, and consumers concerned with safely and preventing accidents for many products in general, but specifically for medium density fiberboard (MDF). The international industrial standard for MDF for measuring highest quality is internal bond (IB, also called tensile strengh) and its smaller percentiles are crucial, especially the first percentile and lower ones. We induce censoring at a value just above the median to weight lower observations more. Using this approach, we have better fits in the lower tails of the distribution, where these samller percentiles are impacted most. Finally, bootstrap estimates of the small percentiles are used to demonstrate improved intervals by our forced censoring approach and the fitted model. There was evidence from the study to suggest that MDF has potentially different failure modes for early failures. Overall, our approach is parsimonious and is suitable for real time manufacturing settings. The approach works for either strengths distributions or lifetime distributions.

• Journal of the Korean Data and Information Science Society
• /
• v.9 no.1
• /
• pp.47-56
• /
• 1998

Zero-Inflated Poisson models are mixed models of the Poisson and Bernoulli models. Recently Zero-Inflated Poisson distributions have been used frequently rather than previous Poisson distributions because the developement of industrial technology make few defects in manufacturing process. It is important that univariate Zero-Inflated Poisson distributions are extended to bivariate distributions to generalize the multivariate distributions. In this paper we proposed three types of the bivariate Zero-Inflated Poisson distributions and obtained these moments. We compared the three types of distributions by using the moments.

• Proceedings of the KAIS Fall Conference
• /
• 2003.11a
• /
• pp.236-242
• /
• 2003

ATM ABR service controls network traffic using feedback information on the network congestion situation in order to guarantee the demanded service qualities and the available cell rates. In this paper we apply the control method using queue length prediction to the formation of feedback information for more efficient ABR traffic control. If backward node receive the longer delayed feedback information on the impending congestion, the switch can be already congested from the uncontrolled arriving traffic and the fluctuation of queue length can be inefficiently high in the continuing time intervals. The feedback control method proposed in this paper predicts the queue length in the switch using the slope of queue length prediction function and queue length changes in time-series. The predicted congestion information is backward to the node. NLMS and neural network are used as the predictive control functions, and they are compared from performance on the queue length prediction. Simulation results show the efficiency of the proposed method compared to the feedback control method without the prediction. Therefore, we conclude that the efficient congestion and stability of the queue length controls are possible using the prediction scheme that can resolve the problems caused from the longer delays of the feedback information.

• The Korean Journal of Applied Statistics
• /
• v.28 no.2
• /
• pp.189-200
• /
• 2015

Stationary bootstrapping is applied to a Lagrangian multiplier (LM) test to test market microstructure noise (MMN) in financial asset prices. A Monte-Carlo experiment shows that the bootstrapping method improves the size of the original LM test which has some size distortion for conditional heteroscedastic models. The proposed test is illustrated for real data sets like KOSPI index and Won-Dollar exchange rate.

• The Korean Journal of Applied Statistics
• /
• v.28 no.2
• /
• pp.281-288
• /
• 2015

In this paper, we study an approximate procedure to evaluate a penalized maximum likelihood estimator (MLE) for a mixed effects model. The procedure approximates the Hessian matrix of the penalized MLE with a structured sparse matrix or an arrowhead type matrix to speed its computation. In this paper, we numerically investigate the gain in computation time as well as approximation error from the considered approximation procedure.