• IE interfaces
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• v.10 no.1
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• pp.119-134
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• 1997

The management of blood inventory is very important within the medical care system. The efficient management of blood supplies and demands for transfusions is of great economic and social importance to both hospitals and patients. For any blood type, there is a complex interaction among the optimal inventory level, daily demand level, daily supply level, transfusion to crossmatch ratio, crossmatch release period, issuing policy and the age of arriving units that determine the shortage and outdate rate. In this paper, we develop an efficient decision rule for blood inventory management in a hospital blood bank which can support efficient hospital blood inventory management using simulation. The primary use of the efficient decision rule will be to establish minimum cost function which consists of inventory levels, period in inventory, outdate and shortage rate for whole blood and various component inventories for a hospital blood bank or a transfusion service. If the administrator compute the mean daily demand for each blood type, the mean daily supply for each blood type, the length of the crossmatch release period and the average transfusion to crossmatch ratio, then it is possible to apply the efficient decision rule to compute the optimal inventory level, inventory period, outdate and shortage rate. This rule can also be used as a decision support system that allows the blood bank administrator to do sensitivity analysis related to controllable blood inventory parameters.

• Journal of Information Technology Applications and Management
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• v.20 no.4
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• pp.221-234
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• 2013

In this paper, we report bankruptcy risk level forecasting result for automobile parts manufacturing industry. With the premise that upstream supply risk and downstream demand risk could impact on automobile parts industry bankruptcy level in advance, we draw upon industry input-output table to use the economic indicators which could reflect the extent of supply and demand risk of the automobile parts industry. To verify the validity of each economic indicator, we applied simple linear regression for each indicators by varying the time lag from one month (t-1) to 12 months (t-12). Finally, with the valid indicators obtained through the simple regressions, the composition of valid economic indicators are derived using stepwise linear regression. Using the monthly automobile parts industry bankruptcy frequency data accumulated during the 5 years, R-square values of the stepwise linear regression results are 68.7%, 91.5%, 85.3% for the 3, 6, 9 months time lag cases each respectively. The computational testing results verifies the effectiveness of our approach in forecasting bankruptcy risk forecasting of the automobile parts industry.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1149-1152
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• 1997

This paper describes a novel approach for allocating transmission costs among users of transmission services. In the suggested approach, the cost share of each participant is proportional to amount of its line flow. To develop individual user's impact, the line utilization factors of each participant are derived by power flow equations of all nodes (i.e., load-flow equations). To deal With the slack bus problem inherent in the conventional load-flow analysis more practically, a additional power supply/demand balance equation is incorporated. Although the developed allocation rule is basically similar to the existing MW-mile method in the aspect of embedded cost allocation, it does not require to get load flow solutions of each wheeling transaction when multiple transmission transactions are considered.

• Journal of Korea Water Resources Association
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• v.47 no.6
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• pp.523-536
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• 2014

A water supply reliability is mainly influenced by water demand, reservoir storage, and inflow change caused from drought. The water supply reliability can vary depending on the method of dam operation. In Korea, the deficit-supply method which complements water deficit as water shortage occurs in downstream areas has been used for the national water resources master plan using K-WEAP, but the prime flow method, an alternative approach, would show different results of water supply reliability in comparison to the deficit-supply method. The objective of this research is to compare and analyze differences in water supply reliability according to dam operation methods. These results can be used to re-evaluate water supply reliability of dam in a circumstance considering steady dam release for instreamflow in downstream and hydroelectric power generation.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.141-146
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• 2008

For the efficient use of thermal energy and its related equipments, optimal energy in view of quality and quantity should be timely provided. The core of thermal energy storage technology deals with an energy efficiency for effective energy storage and supply. The relative importance of thermal energy storage technology has been underestimated so far, and the specific projects on this filed have been performed intermittently. For the efficient and systematic approach of the energy supply system projects on thermal energy storage technology, we conduct the survey on the current status of this field. Firstly, classify into the thermal energy storage and describing the recent research for each system. The necessity and importance of thermal energy storage technology is identified through this study. It reveals that the thermal energy storage is the mandatory technology to solve the difference of supply and demand in thermal loads. It would greatly contribute to the combined heat and power(CHP) system. The urgent technologies for the commercial value and the core technologies for the CHP system are classified with this study.

• KDI Journal of Economic Policy
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• v.14 no.1
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• pp.37-60
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• 1992

This paper applies a Structural VAR approach to a 4 variable system in real GNP, M2, GNP deflator and nominal monthly earnings, disentangling 4 structural shocks, i.e., aggregate demand and supply shocks, wage pushes and various forms of regulations reinforced especially during stabilization process. Preliminary diagnostic tests confirm that the log level of each time series has at least one unit root, though the evidence is somewhat ambiguous for real GNP. One co-integration relationship is found among 4 variables, while no co-integration is found in a subsystem consisting of nomina) variables. The absence of co-integration among nominal variables strongly suggested that money is not neutral even in the long-run. The reduced form is estimated and the structural form is recovered using 6 additional identifying restrictions. Recovered structural shocks are able to capture main episodes of past 20 years, ranging from first and second oil shocks, to strong stabilization policy of early 80's and rapid wage hikes of late 80's. Overall responses of the economy to each structural shock are usually consistent with the standard Keynesian predictions, though some responses seem to be specific to Korean economic environment.

• Korean Management Science Review
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• v.17 no.1
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• pp.117-134
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• 2000

Pubilc utility industries including the electric utility industry are facing a new stream of privatization com-petition with the private sector and deregulation. The necewssity to solve now and in the future power supply and demand problems has been increasing through the sophisticated generation expansion plan(GEP) approach con-sidering not only KEPCo's supply-side resources but also outside resources such as non-utility generation(NUG) demand-side management (DSM). Under the environmental situation in the current electric utility industry a new approach is needed to acquire multiple resources competitively. This study presents the development of a modified electric generation expansion analysis system(EGEAS) model with avoided cost based on the existing EGEAS model which is a dynamic program to develope an optimal generation expansion plan for the electric utility. We are trying to find optimal GEP in Korea's case using our modified model and observe the difference for the level of reliabilities such as the reserve margin(RM) loss of load probability(LOLP) and expected unserved energy percent(EUEP) between the existing EGEAS model and our model. In addition we are trying to calculate avoided cost for NUG resources which is a criterion to evaluate herem and test possibility of connection calculation of avoided cost with GEP implementation using our modified model. The results of our case study are as follows. First we were able to find that the generation expansion plan and reliability measures were largely influenced by capacity size and loading status of NUG resources, Second we were able to find that avoided cost which are criteria to evaluate NUG resources could be calculated by using our modified EGEAS model with avoided cost. We also note that avoided costs were calculated by our model in connection with generation expansion plans.

• Journal of the Korean Geographical Society
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• v.32 no.2
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• pp.245-263
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• 1997

Housing market is segmented through 1) housing supply classified by housing characteristics and 2) housing demand classified by different housing opportunity of household. Moreover, neighborhood plays a role in intensifying housing market segmentation as a factor affecting on decision making relevant to housing supply and demand. while segmented housing markets have different mechanism, existing studies on residential differentiation and housing market have overlooked the characteristic differences among housing submarkets as the studies presume metropolitan housing market to be a single housing market. while the concept of 'residential differentiation' pays much attention on spatial pattern after the ecological approach appeared, the concept of ‘housing submarkets' is explanatory of the process of urban space structure formation. Analysis on housing submarkets makes up for the weak points of the behavioral approach inquiring into socio-economic constraint and different housing opportunity of household.

• Management Science and Financial Engineering
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• v.14 no.2
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• pp.105-118
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• 2008

There are many debates on the topic of the relationship between oil prices and economic growth. Through the repeated processes of conformations and contractions on the subject, two main issues are developed; one is how to define and drive oil shocks from oil prices, and the other is how to specify an econometric model to reflect the asymmetric relations between oil prices and output growth. The study, thus, introduces the unobserved component model to pick up the oil shocks and a first-order Markov switching model to reflect the asymmetric features. We finally employ unique oil shock variables from the stochastic trend components of oil prices and adapt four lags of the mean growth Markov Switching model. The results indicate that oil shocks exert more impact to recessionary state than expansionary state and the supply-side oil shocks are more persistent and significant than the demand-side shocks.

• Proceedings of the Korean DIstribution Association Conference
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• 2000.10a
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• pp.91-105
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• 2000

Results of a study of the coordination effect in stocking and promotional markdown policies for a supply chain consisting of a retailer and a discount outlet (DCO) are reported here. We assume that the products are sold in two consecutive periods: Normal Sales Period (NSP) and subsequent Promotional Sales Period (PSP). When managers in the two periods coordinate, they share information on the demand forecast and jointly decide the stocking quantity, markdown time schedule, and markdown price to maximize mutual profit. In the absence of coordination, decisions are decentralized to optimize the individual party's objective function. Optimal coordination policy for the retailer/DCO problem setting is analyzed, and the coordination policy is compared with the uncoordinated policy to explore factors that make coordination an effective approach.