• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.4
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• pp.159-164
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• 2005

Various compensators are installed into the power system to operate the system economically and stably by maximizing the availability of utilities and power transmission capability. Fixed Capacitor(FC), Mechanical Switched Capacitor(MSC), and FACTS(Flexible AC Transmission Systems) are used to regulate voltage and power flow of the system. When a disturbance occurs in the power system, the Fixed Capacitor operates dependently on the voltage of the power system and cannot change the amount of installation automatically. But compared to other equipment, the Fixed Capacitor is more economical due to its low cost. Since MSC can change the amount of installation according to the state of the power system, operates more effectively than the Fixed Capacitor. FACTS have fast dynamic performance for the transient condition, but the cost is high. Therefore, it is needed to develop an optimized installation planning for the reactive power compensators by considering their dynamic performance and cost. In this paper, an optimized compensator combination and the proposed scheme is proposed and it is applied to KEPCO system in order to show its capabilities.

• International Journal of Advanced Culture Technology
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• v.8 no.1
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• pp.62-70
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• 2020

As an effective means of price discrimination, some suppliers offer trade credit to the distributors in order to stimulate the demand for the product they produce. The availability of the delay in payments from the supplier enables discount of the distributor's selling price from a wider range of the price option in anticipation of increased customer's demand. Since the distributor's lot-size is affected by the demand for the customer, the distributor's lot-size and the selling price determination problem is interdependent and must be solved at the same time. Also, in many common business transactions, the distributor pays the shipping cost for the order and hence, the distributor's ordering cost consists of a fixed ordering cost and the shipping cost that depend on the order quantity. In this regard, we deal with the joint lot-size and price determination problem when the supplier allows delay in payments for an order of a product. The positive effects of credit transactions can be integrated into the EOQ (economic order quantity) model through the consideration of retailing situations, where the customer's demand is a function of the distributor's selling price. It is also assumed that the distributor's order cost consists of a fixed ordering cost and the variable shipping cost. We formulate the distributor's mathematical model from which the solution algorithm is derived based on properties of an optimal solution. A numerical example is presented to illustrate the algorithm developed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.40
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• pp.233-240
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• 1996

A fixed amount compensator is proposed for a process with a linear tool wear function. A Cost model is constructed which involve process adjustment cost and quality loss. Symmetric and asymmetric quadratic functions of the deviation of a quality measurement from the nominal target value are considered as the quality loss functions. Methods of finding optimal values of initial setting and compensation limit are presented and a numerical example is given.

• Journal of the military operations research society of Korea
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• v.12 no.2
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• pp.22-36
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• 1986

The study is to design optimal aircraft allocation model for sufficing the required level of damage, minimizing attrition cost when the aircrafts attack the enemy's fixed target. When friendly aircraft attacks enemy target, the aircraft will suffer the loss due to the enemy's anti-aircraft weapons and aircraft. For this study, it is required that the probability of target damage by the type of aircraft, level of target damage and attrition cost are computed for the application of this model.

• Journal of the Korean Solar Energy Society
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• v.37 no.6
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• pp.69-77
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• 2017

The amount of solar irradiation obtained by a photovoltaic (PV) solar panel is the major factor determining the power generated by a PV system, and the array tilt angle is critical for maximizing panel radiation acquisition. There are three types of PV systems based on the manner of setting the array tilt angle: fixed, semi-fixed, and tracking systems. A fixed system cannot respond to seasonal solar altitude angle changes, and therefore cannot absorb the maximum available solar radiation. The tracking system continually adjusts the tilt angle to absorb the maximum available radiation, but requires additional cost for equipment, installation, operation, and maintenance. The semi-fixed system is only adjusted periodically (usually seasonally) to obtain more energy than a fixed system at an overall cost that is less than a tracking system. To maximize semi-fixed system efficiency, determining the optimal tilt angle adjustment schedule are required. In this research, we conducted a simulation to derive an optimal operation schedule for a semi-fixed system in Seoul, Korea (latitude $37.5^{\circ}$). We implemented a solar radiation acquisition model and PV genereation model on MATLAB. The optimal operation schedule was derived by changing the number of tilt angle adjustments throughout a year using a Dynamic Algorithm. The results show that adjusting the tilt angle 4 times a year was the most appropriate. and then, generation amount of PV system increased 2.80% compared with the fixed system. This corresponds to 99% compared to daily adjustment model. This increase would be quite valid as the PV system installation area increased.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.87-90
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• 2008

Levelized generation cost(LGC) has been widely used in assessing feed-in tariffs(FiT) for electricity generating from new and renewable energies. Current FiTs for renewable electricity in Korea have been fixed and applied with realistic economic data by the efforts of KERI(Korea Electrotechnology Research Institute) since October 2006. Some critical issues on the estimation of LGC are, however, found in KERI's report. Major issues are the estimation of capital cost, the consideration of corporate tax, and the application of economic life cycle in the formulae for LGC. These critical issues are examined and interpreted in a correct way in this paper.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.4
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• pp.425-432
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• 2008

While the Vendor-Managed Inventory(VMI) is a convenient inventory replenishment policy for the customer company, the supplier usually bears the burden of higher inventory and urgent shipments to avoid shortage. Recently some manufacturers begin to fix the production schedule for the next few days (such as three days). Utilizing that information can improve the efficiency of the VMI. In this study, we present a myopic optimization model using a mixed inter programming; and a heuristics algorithm. We compare the performance of the two proposed methods with the existing (s, S) reorder policy. We consider the total cost as the sum of transportation cost and inventory cost at the customer's site. Numerical tests indicate that the two proposed methods significantly reduce the total cost over the (s, S) policy.

• The Journal of Advanced Prosthodontics
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• v.8 no.1
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• pp.53-61
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• 2016

PURPOSE. This study conducted an analysis of cost-effectiveness of the implant and conventional fixed dental prosthesis (CFDP) from a single treatment perspective. MATERIALS AND METHODS. The Markov model for cost-effectiveness analysis of the implant and CFDP was carried out over maximum 50 years. The probabilistic sensitivity analysis was performed by the 10,000 Monte-Carlo simulations, and cost-effectiveness acceptability curves (CEAC) were also presented. The results from meta-analysis studies were used to determine the survival rates and complication rates of the implant and CFDP. Data regarding the cost of each treatment method were collected from University Dental Hospital and Statistics Korea for 2013. Using the results of the patient satisfaction survey study, quality-adjusted prosthesis year (QAPY) of the implant and CFDP strategy was evaluated with annual discount rate. RESULTS. When only the direct cost was considered, implants were more cost-effective when the willingness to pay (WTP) was more than 10,000 won at $10^{th}$ year after the treatment, and more cost-effective regardless of the WTP from $20^{th}$ year after the prosthodontic treatment. When the indirect cost was added to the direct cost, implants were more cost-effective only when the WTP was more than 75,000 won at the $10^{th}$ year after the prosthodontic treatment, more than 35,000 won at the $20^{th}$ year after prosthodontic treatment. CONCLUSION. The CFDP was more cost-effective unless the WTP was more than 75,000 won at the $10^{th}$ year after prosthodontic treatment. But the cost-effectivenss tendency changed from CFDP to implant as time passed.

• Journal of Korean Academy of Nursing Administration
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• v.14 no.2
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• pp.182-195
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• 2008

Purpose: Hospice care represents all meaningful aspects of physical, mental and economical status of the end stage patients. The purpose of this study was to estimate the cost of home-based hospice care. Method: Fifteen nurses participated in counting an hour for requirement and home visit data of 50 end stage patients were analyzed. The method of to estimate the cost of home-based hospice care was three ways. Result: In case, including traffic expense, Singles fixed fee per visit via direct inquiry was 112,970 won but in case, excluding traffic expenses, was 86,036 won and traffic expenses per visit was 26,934 won. Final cost of home-based hospice care integrated the fixed fee per the needed time for visit and fee-for services. The fixed fee per 30 minutes was 35,251 won and 60 minutes was 46,595 won and 90 minutes was 57,939 won. We included pain management and the management of emergency and bereavement care among fee-for services. Conclusion: The cost of hospice care should be establish for not only patient but the living spouse, families, and children of the dying and for anyone else affected by any patient's death.

• Journal of the Korean Society of Safety
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• v.30 no.3
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• pp.13-19
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• 2015

Railway vehicle equipment goes back again to the state just before when failure by the repair. In repairable system, we are interested in the failure interval. As such, a statistical model of the point process, NHPP power law is often used for the reliability analysis of a repairable system. In order to derive a quantitative reliability value of repairable system, we analyze the failure data of the air brake system of the train line 7. The quantitative value is the failure intensity function that was modified, converted into a cost-rate function. Finally we studied the optimal number and optimal interval in which the costs to a minimum consumption point as cost-rate function. The minimum cost point was 194,613 (won/day) during the total life cycle of the braking system, then the optimal interval were 2,251days and the number of optimal preventive maintenance were 7 times. Additionally, we were compared to the cost of a currently fixed interval(4Y) and the optimum interval then the optimal interval is 3,853(won/day) consuming smaller. In addition, judging from the total life, "fixed interval" is smaller than 1,157 days as "optimal interval".