• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.159-168
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• 2015

Aggregate Production Planning determines levels of production, human resources, inventory to maximize company's profits and fulfill customer's demands based on demand forecasts. Since performance of aggregate production planning heavily depends on accuracy of given forecasting demands, choosing an accurate forecasting method should be antecedent for achieving a good aggregate production planning. Generally, typical forecasting error metrics such as MSE (Mean Squared Error), MAD (Mean Absolute Deviation), MAPE (Mean Absolute Percentage Error), and CFE (Cumulated Forecast Error) are utilized to choose a proper forecasting method for an aggregate production planning. However, these metrics are designed only to measure a difference between real and forecast demands and they are not able to consider any results such as increasing cost or decreasing profit caused by forecasting error. Consequently, the traditional metrics fail to give enough explanation to select a good forecasting method in aggregate production planning. To overcome this limitation of typical metrics for forecasting method this study suggests a new metric, WACFE (Weighted Absolute and Cumulative Forecast Error), to evaluate forecasting methods. Basically, the WACFE is designed to consider not only forecasting errors but also costs which the errors might cause in for Aggregate Production Planning. The WACFE is a product sum of cumulative forecasting error and weight factors for backorder and inventory costs. We demonstrate the effectiveness of the proposed metric by conducting intensive experiments with demand data sets from M3-competition. Finally, we showed that the WACFE provides a higher correlation with the total cost than other metrics and, consequently, is a better performance in selection of forecasting methods for aggregate production planning.

• Journal of Korean Institute of Industrial Engineers
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• v.15 no.2
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• pp.1-10
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• 1989

This paper deals with a single-facility multiproduction model concerning the basic cyclic scheduling. The aim is to obtain the production order of each product in a cycle and the cycle frequency for minimizing the setup costs and inventory carrying costs of all products. The problem is formulated by LP and it shows that the optimal solution derived dominates the solution of non-cyclic scheduling model on some conditions.

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.21-27
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• 2010

This paper examines the long-run social welfare maximization problems facing public utilities, which includes consideration of the cost of capital or other fixed costs of production, from which it derives optimal investment decisions in a reliability differentiated pricing based market. Reliability differentiated pricing policies lead to straightforward mathematical results on optimal investment decisions in generation and transmission expansion planning. This paper presents the mathematical conditions for optimal investment decisions.

• Journal of Korean Society for Quality Management
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• v.26 no.3
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• pp.46-59
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• 1998

The problem of selecting optimal target values for the mean of the quality characteristic of interest for a production process in which an item is sold in one of two market with different profit / cost structures or reworked. Two profit models are constructed which involve four profit / cost components: profit, production, inspection, and rework costs. Assumed that the quality characteristic of interest is normally distributed, methods of finding the most profitable process mean are presented and a numerical example is given.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.1
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• pp.51-58
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• 1997

In this paper, we propose a stochastic LP model for determining an optimal input quantity in a single-product multi-stage production system with random yields. Due to the random yields in our model, each stage of the production system can result in defective items, which can be re-processed or scrapped at certain costs. We assume that the random yield at each stage follows an independent discrete empirical distribution. Compared to dynamic programming models that prevail in the literature, our model can easily handle problems of larger sizes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.35
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• pp.89-94
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• 1995

Previous MRP models were developed without considering learning effects on the determination of the production lot size environment. The only consideration was the setup and inventory holding costs. In this paper the proposed MRP model were developed incorporated the effects of learning. The result of this model show that learning significantly influence the production lot size and total variable cost. The numerical examples have been used to illustrated the impact of proposed model.

• Korean Journal of Agricultural Science
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• v.33 no.1
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• pp.57-66
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• 2006

This study attempts to investigate the possible extent that main spicy vegetables' competitiveness can be improved through various measures. More widely open the agricultural market becomes, more important enhancing the competitiveness of domestic agricultural products is especially in high tariff products such as red-pepper and garlic. Up to date, numerous measures have been applied to those products for enhancing the competitiveness by government, regional agencies, and producer's organizations. However, there is few studies about how much the competitiveness can be improved as a whole from implementing the diverse methods. Following the results, the competitiveness of red-pepper and garlic can be improved up to 70% and 50% respectively by reducing production costs.

• Korean Journal of Organic Agriculture
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• v.24 no.2
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• pp.201-219
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• 2016

To internalize climate-related external costs from agricultural production and food consumption Pigou taxes and carbon credits increase private costs for food. Voluntary GHG reduction program for carbon-neutral food can be advantageous over such policy measures since they avoid higher food prices for the poor. The pilot project of low-carbon agriculture certification system is to reduce GHG emissions from agricultural production and enhance the competitiveness of domestic agricultural products. This study examines producers', distributors', and consumers' perceptions of the low-carbon agriculture certification system and analyzes alternatives to promote the low-carbon certificated agricultural products.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.4
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• pp.329-336
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• 2012

Objectives: The aim of this study is to analyze main problems on occupational safety and hygiene in construction sites and to suggest some improvement methods. In order to decrease industrial accidents, I emphasize the approach paradigm shifts according to characteristics of construction workers. Methods: Pointing out the irrationality of current institutions by comparing bad outcomes of occupational safety and hygiene in construction industry and characteristics of construction workers. Results: In order to decrease industrial accidents, we need some approach paradigm shifts; the supply method of industrial safety and health fundamentals on the construction industry level, the accident rate calculation by using the actual construction workforce instead of an estimation, institutionalizing the prevention efforts themselves for industrial accidents, securing enough production costs for the precondition of occupational safety and hygiene in construction sites. Conclusions: I ascertain the need of the approach paradigm shifts for decreasing industrial accidents in the construction industry.

• Korean Journal of Organic Agriculture
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• v.18 no.1
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• pp.1-19
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• 2010

This paper evaluates potential environmental impacts and external costs on rice production of Korea. The investigation is based on LCA in agricultural area which estimates inputs and outputs of rice production system in quantitative way. The results show that environmental impacts on organic rice(4.49E-08 DALY/kg) is level on 4.5% out of conventional rice(9.97E-07 DALY/kg). The external costs of organic and conventional rice are 4.04won/kg and 89.52won/kg respectively. The balance of both organic and conventional rice which is 85.48won/kg represents monetary value on improvement of environmental effects as producing organic rice.