• 한국경영과학회지
• /
• 제19권3호
• /
• pp.81-91
• /
• 1994

This paper is to build an economic production quantity model for situations, in which, during the stockout period, a fraction .betha.(backorder ratio) of the demand is backordered and remaining fraction (1-.betha.) is lost. This paper develops an objective function representing the average annual cost of a production system by defining a time-weighted backorder cost and a lost sales penalty cost per unit lost under the assumptions of deterministic demand rate and deterministic production rate, and provides an algorithm for its optimal solution. At the extreme .betha.= 1, the presented model reduces to the Fabrycky's model with complete backorders.

• 한국공작기계학회논문집
• /
• 제17권1호
• /
• pp.43-49
• /
• 2008

This study is about an influence of harmful factors of welding fumes such as Fe, Mn, Cu, Zn to workers who inhales them in welding sites. The influence can be measured with the density of heavy metals in blood after welding. The main factors of the measurement are TWA, a density of welding fume, and a level of heavy metals. The results indicate that there is a positive effect of moving fans as a way of improving the condition in welding workplaces. While welding was done, TWA exceeded the level of Fe 40% and Zn 10% and the level of heavy metals in blood was below the standard for the workers who were under the experiment. Also when the wind was applied on the front side by a fan, the welding fume significantly reduced. It can be concluded that wearing protection gears with safety devices is one of important factors.

• 대한임베디드공학회논문지
• /
• 제8권4호
• /
• pp.227-233
• /
• 2013

In this paper, we propose an implementation of pH reader on Android smart phone by using Eclipse and SDK. After taking a picture of pH spectrum and tested litmus paper at the same time, we save the picture. From the picture, reference values in RGB and YUB of all pH color in the spectrum are obtained and then those of a chosen point by user in the litmus paper are to be compared with. The distances between the reference colors and the litmus paper's color are measured by Euclidean distance in RGB or YUB coordinate. The nearest two pH values are taken to find the weighted average of the result. Series of test show the proposed scheme is feasible and has performance within 10% error.

• 전기전자학회논문지
• /
• 제11권4호
• /
• pp.307-314
• /
• 2007

In this paper, we propose an image contrast enhancement algorithm for an LCD TV. The proposed algorithm consists of two processes: the image segmentation process and the tone curve control process. The first process uses an automatic threshold technique to decompose an input image into two regions and then utilizes a hierarchical structure for real-time processing. The second process generates a gray level tone curve for contrast enhancement using a weighted sum of average tone curves for two segmented regions. Experimental result shows that the proposed algorithm outperforms the conventional contrast enhancement methods for an LCD TV.

• 한국산업보건학회지
• /
• 제1권2호
• /
• pp.154-163
• /
• 1991

Particulate matter exposure leva1 of welders and grinding workers was evaluated in Banwol and Changwon industry complexes. Full period single sample and full period consecutive samples were collected with personal air samplers attached to workers. Compliance difference with 8-hour time weighted average (TWA) was compared by Korean strategy and the classification system recommended by OHSA for employee exposure to particulates. And difference of compliance was compared according to precision of measurement and analysis (total precision). Compliance rate was depended on the total precision, therefore, quality control of measurement and analysis was important.

• 품질경영학회지
• /
• 제13권1호
• /
• pp.56-64
• /
• 1985

This paper presents a general algorithm of multi-item continuous review models to obtain simultaneous solutions for ordering quantities and reorder points for each item in an inventory, while satisfying constraints on average inventory investment and reordering workload. Two models are formulated'in each model the heuristic method is utilized, and the partial back-logging is considered. In the first model, the objective function is the minimization of total inventory variable cost. In the second model, the objective function is the minimization of total time-weighted shortages, and the ordering, holding, and stockout costs in this model are independent each other. A numerical example is also solved to present application of each model.

• 한국안전학회지
• /
• 제20권1호
• /
• pp.126-132
• /
• 2005

The purpose of this study is to propose a method to evaluate task complexity using CIFs(Complexity Influencing Factors). We developed a method that CIFs can be used in the evaluation of task complexity using fuzzy linguistic approach. That is, a fuzzy linguistic multi-criteria method to assess task complexity in a specific task situation was proposed. The CIFs luting was assessed in linguistic terms, which are described by fuzzy numbers with triangular and trapezoidal membership function. A fuzzy weighted average algorithm, based on the extension principle, was employed to aggregate these fuzzy numbers. Finally, the method was validated by experimental approach. In the result, it was validated that TCIM(Tink Complexity Index Method) is an efficient method to evaluate task complexity because the correlation coefficient between task performance time and TCI(Task Complexity Index) was 0.699.

• Journal of the Korean Data and Information Science Society
• /
• 제26권2호
• /
• pp.525-533
• /
• 2015

Modern production process is a very complex structure combined observations which are correlated with several factors. When the error signal occurs in the process, it is very difficult to know the root causes of an out-of-control signal because of insufficient information. However, if we know the time of the change, the system can be controlled more easily. To know it, we derive a maximum likelihood estimator (MLE) of the change point in a process when observations are from a multivariate IMA(1,1) process by monitoring residual vectors of the model. In this paper, numerical results show that the MLE of change point is effective in detecting changes in a process.

• 산업경영시스템학회지
• /
• 제22권52호
• /
• pp.337-345
• /
• 1999

The long-tailed, positively skewed exponential distribution can be made into an almost symmetric distribution by taking the exponent of the data. In these situations, to use the traditional shewhart control limits on an individuals chart would be impractical and inconvenient. The transformed data, approximately bell-shaped, can be plotted conveniently on the individuals chart and exponentially weighted moving average chart. In this paper, using modifying statistics with transformed exponential of the data, we give a method for constructing control charts. Selecting method of exponent for individual chart is evaluated. And consider that smaller weight being assigned to the older data as time process and properties and taking method of exponent($\theta$), weighting factor($\alpha$) are suggested. Our recommendation, on the basis result of simulation, is practical method for EWMA chart.

• ETRI Journal
• /
• 제31권2호
• /
• pp.237-239
• /
• 2009

A whole-body voxel model of a 7-year-old male volunteer was developed from 384 axial magnetic resonance images (MRIs). The MRIs were acquired with intervals of 3 mm for the entire body in a body coil. In order to reduce the MRI acquisition time for the child, the repetition and echo times under T1 weighted image were chosen to be 566 ms and 8 ms, respectively. The MRIs were classified according to 30 types of tissues with known electrical parameters. The developed voxel model was adjusted to the physical average of 7-year-old Korean boys. The body weight of the adjusted model, calculated with the mass tissue densities, is within a 6% difference from the 50th percentile weight.