• The Journal of Bigdata
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• v.5 no.2
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• pp.111-120
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• 2020

Despite the recent economic contraction caused by the Corona 19 incident, interest in the residential environment is growing as more people live at home due to the increase in telecommuting, thereby increasing demand for remodeling. In addition, the government's real estate policy is also expected to have a visible impact on the sales of the interior and furniture industries as it shifts from regulatory policy to the expansion of housing supply. Accurate demand forecasting is a problem directly related to inventory management, and a good demand forecast can reduce logistics and inventory costs due to overproduction by eliminating the need to have unnecessary inventory. However, it is a difficult problem to predict accurate demand because external factors such as constantly changing economic trends, market trends, and social issues must be taken into account. In this study, LSTM model and 1D-CNN model were compared and analyzed by artificial intelligence-based time series analysis method to produce reliable results for manufacturers producing furniture components.

• Health Policy and Management
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• v.4 no.1
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• pp.123-137
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• 1994

The objectives of this research is to find the factors which determined hospital profitability. The unit of analysis is hospital, and the data is collected from two sources. One source is derived from Ministry of Health and Social Affairs(4 years' data from 134 hospitals), and another source is derived from Sam-II Accounting Co.(1 year's data from 37 hospitals). Hospital profitability, which is dependent variable in our research, is measured with financial ration, such as ROI(reture on investment). The major findings are as follows; 1) The hospital profitability is determined with not hospital type itself but management-incentives associated with hospital type. 2) The maximum profitability is obtained in 775 bed-size. 3) The hospital location isn't a factor to determine profitability 4) The internal control and management, such as account receivables, inventory, fixed assert investment, is major factor to hospital profitability.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.1
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• pp.105-113
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• 1998

This paper deals with a production line which consists of two production stages that are separated by a finite storage buffer. The inventory level in the storage buffer controls the production rate of the preceding stage. That is, the production rate becomes high (low) when the buffer inventory is low (high). We analyze the system characteristics utilizing the Markov process theory and then find an optimal control policy which maximizes a given system profit function. Also, a sensitivity analysis is made to examine the effects of various system parameters on the system performances.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.137-145
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• 2012

본 연구는 공급자(supplier), 소매상(retailer) 그리고 고객(customer)으로 구성된 2 단계 공급사슬에서 소매상의 관점에서 소매상의 최적 재고정책 결정에 관한 문제를 다루었다. 공급자는 수요 증대를 목적으로 소매상의 주문량에 따라 다단계로 일정기간동안 제품 판매대금에 대한 지불 연기(외상)를 허용하고, 고객의 수요는 소매상의 제품 재고량에 영향을 받는다는 가정 하에 재고 모형을 설계하였다. 모형 분석을 통하여 소매상의 이익을 최대화하는 최적 주문량 결정 방법을 제시하였고, 예제를 통하여 그 제시된 해법의 타당성을 보였다.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.5
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• pp.447-452
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• 2015

This paper considers a two-stage make-to-stock production system. The first stage produces a single-component and the second stage produces a make-to-stock product using components. In addition to internal demands, the first stage faces external demands with the option of accepting or rejecting. To ration component inventory, the manufacturer adopts a static rule. This paper analyzes the production controls at both facilities that maximizes the manufacturer's profit. Using the Markov decision process model, we characterize the optimal production policy by two monotonic switching curves.

• IE interfaces
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• v.13 no.3
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• pp.424-430
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• 2000

Supply chain management (SCM) is an area that has recently received a great deal of attention in the business community. While SCM is relatively new, the idea of coordinated planning is not. During the last decades, many researchers have investigated multi-stage inventory problems. However, only a few papers address the problem of cost-optimal coordination of multi-stage inventory control with respect to service measures. Even published approaches have a shortcoming in dealing with a delivery lead time consisted of a shipping time and a waiting time. Assumed that there is no waiting time, or that the delivery lead time is implicitly compounded of a shipping time and a waiting time, the problem is often simplified into a multi-stage buffer allocation and a single-stage stochastic buffer sizing problem at all installations. This paper presents a simulation-based heuristic algorithm and a comparison with others for the problem that cannot be decomposed into a multi-stage buffer allocation and a single-stage stochastic buffer sizing problem because the waiting time ties together all stages. The comparison shows that the simulation-based heuristic algorithm performs better than other approaches in saving average inventory cost for both Poisson and Normal demands.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.21
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• pp.133-141
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• 1990

Human blood is a perishable product : it has a legal lifetime of 21 days from collection, during which it can be used for transfusion to a Patient of the same type, and after which it has to be discarded. Therefore, blood must be supplied safely and effectively because it is one of the medical resources which keep humanlife. In this study, the effects of blood issuing policies on average inventory levels and average age of blood at transfusion are determined by simulation applied the theory of absorbing Markov chains. And as a practical study, the daily demand distribution of blood is estimated by using the data of B General Hospital. The distribution estimated follows poisson distribution and the estimator of parameter estimated from the poisson distribution is 0.762. Simulation is done by using the parameter. The most important problem when control blood is the amount of outdata. So we compared random policy with Modified LIFO and Modified FIFO by using outdata. As a results it is shown that Modified LIFO and Modified FIFO by using outdata. As a results it Is shown that Modified LIFO and Modified FIFO present better issuing policy than Random Policy.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.1
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• pp.87-100
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• 2018

Fast economic growth and urbanization of China have been causing air pollution not only over its domestic but transboundary atmosphere. Recent high fine particle pollution episodes in China made the government move toward more stringent air pollution control policies - which are mostly fuel switching and emissions control. In this research, we tried to understand characteristics of Chinese emissions and their change by analyzing its emissions inventory by year, sector, and region. From the inter-comparison of existing bottom-up emission inventories, we found relatively good agreements (<20% difference) for $SO_2$ and $NO_x$, but 30% or more discrepancies for some pollutants. Inter-comparison with top-down $NO_x$ emissions estimates also showed 20~50% differences by year. The regional distribution and inter-annual changes of emissions revealed different stages of energy/fuel mix and policy penetration. Early increase of pollutants emissions in the eastern part of China might give strong influences to the Korean peninsular in early 2000s but, more stringent control in that region would help improving air pollution in Korea in near future.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.42
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• pp.31-38
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• 1997

The main objective of this research is to develop a model to select the optimal input service level for a distribution center - multi branch inventory distribution system. With the continuous review policy, the distribution center places an order for specific order quantity to an outside supplier, and the order quantity is replenished after a certain lead time. Also, each branch places an order for particular order quantity to the distribution center to satisfy the customer demands, and receives the replenishment after a lead time. When an out of stock condition occurs during an order cycle, a backorder is placed to the upper level to fill the unfilled demands. With these situation, variable demand and variable lead time are used for better industrial practice. Further, actual lead times with a generic lead time distribution are used in developing the control model. Under the actual lead time model, the customer service measures actually attained for the distribution center and each branch are explained as the effective customer service measures. Thus, throughout the optimal control (using computer search procedures), we can select the optimal input service levels for the distribution center and each branch to attain the effective service level for each branch which is consistent with the goal level of service for each branch. At the same time, the entire distribution system keeps minimum inventories.

• Particle and aerosol research
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• v.12 no.3
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• pp.81-94
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• 2016

Managing hazardous air pollutants (HAPs) becomes an important issue with the amendment of the Clean Air Conservation Act in 2012. In this study, to develop an effective air quality management policy direction against the HAPs in Korea, (1) the HAPs control policies in the USA, United Kingdom, Japan, and the South Coast Air Quality Management District (SQAQMD) are reviewed, (2) the state of the art of the HAPs management in Korea are studied, and (3) policy directions are suggested. It was found that each country has its own policy priority and management directions. It was also found that the current HAPs management status is far behind to the countries compared in HAPs identification, emission inventory, monitoring, modeling, and risk management. Further policy directions are suggested.