• Journal of the Korean Data and Information Science Society
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• v.28 no.2
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• pp.271-286
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• 2017

The objective of this paper is to evaluate whether longevity risk is properly managed in Korean life insurance industry by measuring longevity risk in the viewpoint of natural hedge. According to analysis, the sum of the reserve of annuity and that of whole life insurance appears to decrease in the case both reserve of annuity and whole life insurance are shocked by same degree and also the mortality rate of the aged policyholders is improved faster than that of the less aged policyholders. Although the sum of the reserves increases only when the mortality improvement of annuity policyholders is higher than that of whole life insurance policyholders by two times, more than 60% of reserve increase of annuity is found to be offset by natural hedge. Thus, it is judged that the longevity risk of Korea life insurance industry is properly managed by natural hedge.

• The Korean Journal of Applied Statistics
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• v.31 no.1
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• pp.77-96
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• 2018

A reverse mortgage provides a pension until the death for the insured or last survivor. Long-term risk management is important to estimate the contractual period of a reverse mortgage. It is also necessary to study prediction methods of mortality rates that appropriately reflect the improvement trend of the mortality rate since the extension of the life expectancy, which is the main cause of aging, can have a serious impact on the pension financial soundness. In this study, the Lee-Carter (LC) model reflects the improvement in mortality rates; in addition, multiple life model are also applied to a reverse mortgage. The mortality prediction method by the traditional LC model has shown a dramatic improvement in the mortality rate; therefore, this study suggests mortality projection based on the projection of the skewness for the mortality that has been applied to appropriately reflect the improvement trend of the mortality rate. This paper calculates monthly payments using future mortality rates based on the projection of the skewness of the mortality. As a result, the mortality rates based on this method less reflect the mortality improvement effect than the mortality rates based on a traditional LC model and a larger pension amount is calculated. In conclusion, this method is useful to forecast future mortality trend results in a significant reduction of longevity risk. It can also be used as a risk management method to pay appropriate monthly payments and prevent insufficient payment due to overpayment by the issuing institution and the guarantee institution of the reverse mortgage.

• The Korean Journal of Applied Statistics
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• v.28 no.3
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• pp.393-406
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• 2015

We examine how to model mortality risk using the adaptation of the mean-reverting processes for the two factor model proposed by Cairns et al. (2006b). Mortality improvements have been recently observed in some countries such as United Kingdom; therefore, we assume long-run mortality converges towards a trend at some unknown time and the mean-reverting processes could therefore be an appropriate stochastic model. We estimate the parameters of the two-factor model incorporated with mean-reverting processes by a Metropolis-Hastings algorithm to fit United Kingdom mortality data from 1991 to 2015. We forecast the evolution of the mortality from 2014 to 2040 based on the estimation results in order to evaluate the issue price of a longevity bond of 25 years maturity. As an application, we propose a method to quantify the speed of mortality improvement by the average mean reverting times of the processes.

• The Korean Journal of Applied Statistics
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• v.29 no.1
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• pp.41-59
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• 2016

There have been continuous improvements in human life expectancy. Life expectancy is as a key factor in an aging population and can wreak severe damage on the financial integrity of pension providers. Hence, the projection of the accurate future mortality is a critical point to prevent possible losses to pension providers. However, improvements in future mortality would be overestimated by a typical mortality projection method using the Lee-Carter model since it underestimates the mortality index ${\kappa}_t$. This paper suggests a mortality projection based on the projection of the skewness of the mortality versus the typical mortality projection of the Lee-Carter model based on the projection of the mortality index, ${\kappa}_t$. The paper shows how to indirectly estimate future t trend with the skewness of the mortality and compares the results under each estimation method of the mortality index, ${\kappa}_t$. The analysis of the results shows that mortality projection based on the skewness presents less improved mortality at an elderly ages than the original projection.

• Tunnel and Underground Space
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• v.30 no.5
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• pp.433-445
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• 2020

Professional TBM Operator is in short supply worldwide, and insufficient construction experience of new personnel using TBM can lead to a decline in response capabilities when various construction risks occur. The fact that the TBM construction quality greatly depends on the skill and experience of the TBM operator, and the decrease in productivity due to insufficient skilled manpower, and the decrease in safety due to the decrease in skill level are frequently discussed problems in the TBM industry. To this end, several overseas companies and organizations have developed simulators, and a simulator is being developed in Korea. The International Tunneling Association is planning a comprehensive training, including classroom training, e-learning, simulator training and field training. Given the progress at home and abroad, TBM driver training and formal recognition of training through certification or licensing is expected to become the norm in the near future.