• Journal of the Korean Data Analysis Society
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• v.20 no.6
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• pp.2953-2966
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• 2018

Housing prices are closely related to various variables that indicate macroeconomic conditions. In this paper, empirical analysis based on data is performed referring to previous studies. Focusing on the policy interest rate among the factors affecting the housing price, the non-linear impulse responses of other variables to the interest rate shock are analyzed. Using the random forest algorithm, the variable importance scores of the macroeconomic variables presented in the previous studies are calculated. After selecting the variables through this process, the impulse responses are calculated using a model that can capture non-linearity. According to the model, the responses of housing prices to the policy rate is only significant when the rate is raised. Especially, the impulse response is amplified when the shock increases due to the non-linear characteristics that can not be captured by the traditional VAR methodology. The analysis results suggest that the interest rate as a policy instrument should be approached from a more cautious perspective.

• Proceedings of the Korean Statistical Society Conference
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• 2004.11a
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• pp.295-300
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• 2004

We consider a G/M/1 queue with two-stage service policy. The server starts to serve with rate of ${\mu}1$ customers per unit time until the number of customers in the system reaches A. At this moment, the service rate is changed to that of ${\mu}2$ customers per unit time and this rate continues until the system is empty. We obtain the stationary distribution of the number of customers in the system.

• Journal of Applied Reliability
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• v.11 no.4
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• pp.409-417
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• 2011

In this paper, we consider a replacement model following the expiration of warranty. In other words, this paper proposes the optimal replacement policy for a repairable system following the expiration of payable renewing replacement-non-renewing minimal repair warranty. The expected cost rate per unit time from the user's perspective is used to determine the optimality of the replacement policy. Thus, we derive the expressions for the expected cycle length and the expected total cost to obtain the expected cost rate per unit time. Finally, the numerical examples are presented for illustrative purpose.

• Journal of Applied Reliability
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• v.14 no.2
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• pp.122-128
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• 2014

In this paper, we consider the periodic preventive maintenance model for a repairable system following the expiration of extended warranty under replacement-repair warranty. Under the replacement-repair warranty, the failed system is replaced or minimally repaired by the manufacturer at no cost to the user. Also, under extended warranty, the failed system is minimally repaired by the manufacturer at no cost to the user during the original extended warranty period. As a criterion of the optimality, we utilize the expected cost rate per unit time during the life cycle from the user's perspective. And then we determine the optimal preventive maintenance period and the optimal preventive maintenance number by minimizing the expected cost rate per unit time. Finally, the optimal periodic preventive maintenance policy is given for Weibull distribution case.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.410-412
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• 2002

So far, electricity rate under the midnight hour incorporates policy consideration and maintains fixed irrespective of generation cost. Therefore, the promotion of midnight power apparatus has been rapidly increased due to increasing difference in substitute heating cost. This paper estimates the power supply cost during midnight times and analyzes the rate mechanism which can promote economic midnight power apparatus. In addition it provides the alternative on the direction of policy after the restructuring.

• Proceedings of the Safety Management and Science Conference
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• 2007.11a
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• pp.503-516
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• 2007

USA has distinct differences of economic policy by a ruling party. And, USA economy has mainly influenced on it of Korea. So, we examine whether a ruling party of Korea has different regime including rate of return in stock market. The Republican Party and Democratic Party have based on Milton Friedman and Keynes economy at each other's economic policy in the USA The Republican Party and Democratic Party have different interest level and excess return on equity, GDP growth rate, unemployment rate. Also, a ruling party of Korea has different regime and economic activity in this paper.

• Communications for Statistical Applications and Methods
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• v.25 no.1
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• pp.91-97
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• 2018

In this paper, we show that there exists an optimal investment policy for the surplus in a risk model, in which the surplus is continuously invested to other business at a constant rate a > 0, whenever the level of the surplus exceeds a given threshold V > 0. We assign, to the risk model, two costs, the penalty per unit time while the level of the surplus being under V > 0 and the opportunity cost per unit time by keeping a unit amount of the surplus. After calculating the long-run average cost per unit time, we show that there exists an optimal investment rate $a^*$>0 which minimizes the long-run average cost per unit time, when the claim amount follows an exponential distribution.

• Journal of the Korean Society for information Management
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• v.32 no.1
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• pp.43-62
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• 2015

This study was implemented to suggest various indicators of collection evaluation for collection development policy in public libraries. For the sake of the exploratory research, this study tried to show the usability of indicators of collection evaluation through actual data of a case study. Also to analyze indicators of collection evaluation, this study used the ten years circulation records of the Gwangjin District Public Library in Seoul. Majors indicators of collection evaluation were the rate of use and use factor of purchasing books by annual, the rate of use and use factor of librarian's recommended books by annual, the rate of non circulating books by annual, and the rate of use by residence annually.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.5
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• pp.91-102
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• 2020

The study investigates the relationship between the inflation rate and economic growth to find out the optimal inflation threshold for economic growth. Therefore, this study applied an ordinary least square model (OLS) and the ordinal regression model, and collected the time-series data from 1996 to 2017 to test the relationship between inflation and economic growth in the short-term and long-term. The sample fits the model and is statistically significant. The study showed that 96.6% of correlation between inflation rate and economic growth are close and 4.5% of optimal inflation threshold is appropriate for economic growth. It finds that the optimal inflation threshold is base to perform economic growth, besides the inflation rate is positively related to economic growth. The results support the monetary policy appropriately. This study identifies issues for Government to consider: have a comprehensive solution among macroeconomic policies, monetary policy, fiscal policy and other policies to control and maintain the inflation and stimulate growth; have appropriate policies to regulate inflation to stimulate economic growth over the long term; set a priority goal for sustainable economic growth; not pursue economic growth by maintaining the inflation rate in the long term, but take appropriate measures to stabilize the inflation at the optimal inflation threshold.

• Health Policy and Management
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• v.31 no.2
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• pp.180-187
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• 2021

Background: This study analyzed the effect of applying the diagnosis-related group (DRG)-based payment system, which was implemented in July 2012 for hospitals and clinics nationwide, on the cesarean section rate. Methods: The subjects of the study were divided into new groups that participated in the payment system after July 2012 and maintenance groups that participated in the payment system before July 2012. As an analysis method, a difference-in-difference analysis, which is a quasi-experimental design, was used. The risk-adjusted cesarean section rate was used as a dependent variable. Results: Seven risk factors (malpresentation of fetus, eclampsia, multiple pregnancies, problems in the placenta, previous Cesarean section, cephalopelvic disproportion, problems in amniotic fluid) were included in the final risk-adjustment model, and found to have a statistically significant relationship with the cesarean section rate. Results showed that the risk-adjusted cesarean section rate increased significantly in new groups after the application of the DRG-based payment system. Conclusion: Study results provided policy implications for the reorganization of the DRG-based system should that reflects the demands of obstetricians, such as organizing a consultative body with obstetricians and establishing a reasonable fee.