• Journal of Digital Convergence
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• v.12 no.8
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• pp.67-76
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• 2014

In this study, we investigated opinion leaders' communication activities on Facebook and analyzed the differences of communication patterns on Facebook between Korean and US college students. As a primary source of information, we conducted an online survey to collect data from students currently enrolled at two different universities in US. Additionally, we utilized online survey data previously collected from Korean students. According to our analysis, we found that US male students had more active opinion leadership than Korean male students. Also, opinion leadership of Korean students' was significantly associated with both active and passive communication patterns on Facebook whereas opinion leadership of US students' was significantly associated with passive communication patterns.

• Journal of Digital Convergence
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• v.11 no.5
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• pp.201-209
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• 2013

This study is an application of facebook (FB) as a strategic communication of viral marketing. Old fashioned advertising and public relation in facebook are not effective at social network service(SNS) environment, and a different marketing communication is needed because facebook is essentially oriented for building relationship among people. The study assumes that an opinion leader might exist at facebook and tries to find out how facebook users show a pattern of communication based on level of opinion leadership regarding a product. The findings showed that people with high opinion leadership communicated more actively than people with low opinion leadership. This study will contribute to segment seed consumers using opinion leadership in facebook.

• The Korean Journal of Applied Statistics
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• v.21 no.5
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• pp.739-754
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• 2008

Researches on conversion formulas between multiple decrement models and the associated single decrement models have focused on calculating yearly-based conversion formulas. In practice, actuaries may be more interested in monthly-based conversion formulas. Multiple decrement tables and their associated single decrement tables consist of yearly-based rates of multiple decrements and absolute rates of decrements, respectively. This paper derives conversion formulas from yearly-based absolute rates of decrements to monthly-based rates of decrement due to cause j under the uniform distribution of decrements(UDD). Next, it suggests conversion formulas from monthly-based absolute rates of decrements to monthly-based rates of decrement due to cause j under UDD. In addition, it calculates conversion formulas from yearly-based rates of decrement due to cause j to the corresponding absolute rates of decrements under UDD or constant force assumption. Some numerical examples are discussed.

• Communications for Statistical Applications and Methods
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• v.16 no.2
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• pp.249-264
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• 2009

Equity-indexed annuities(EIAs) provide their customers with the greater of either the return linked to the underlying index or the minimum guaranteed return. Insurance companies have developed EIAs to attract customers reluctant to buy traditional fixed annuities because of low returns and also reluctant to buy mutual funds for fear of the high volatility in the stock market. This paper proposes a new type of EIA embedded with an outside barrier option with flexible monitoring period in order to increase its participation rate. It also derives an explicit pricing formula for this proposed product, and discusses numerical examples to show relationships among participation rate, barrier level, index volatility and correlation.

• The Korean Journal of Applied Statistics
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• v.21 no.6
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• pp.1045-1063
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• 2008

This paper derives conversion formulas from yearly-based absolute rates of decrements to monthly-based rates of decrement due to cause j under FI (fractional age independence) assumption that is a generalization of UDD assumption. Next, it suggests conversion formulas from monthly-based absoluterates of decrements to monthly-based rates of decrement due to cause j under FI assumption. In addition, it calculates conversion formulas from yearly-based rates of decrement due to cause j to the corresponding monthly-based absolute rates of decrements under FI assumption. Some numerical examples are discussed.

• The Korean Journal of Applied Statistics
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• v.29 no.1
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• pp.231-242
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• 2016

X-13-ARIMA (a popular time series analysis software) provides $3{\times}3$, $3{\times}5$, $3{\times}9$, $3{\times}15$ moving average filters for seasonal adjustment. However, there has been questions on their performance and the need for new filters is a constant topic due to Korean economic time series often containing higher irregularity and more various seasonality than other countries. In this study, two newly developed seasonal moving average filters, $3{\times}7$ and $3{\times}11$, are introduced. New filters were implemented in X-13-ARIMA and applied to 15 economic time series to demonstrate their suitability and reliability. The result shows that some series are more stable when using new seasonal moving average filters. More accurate time series analyses would be possible if newly proposed filters are used together with existing filters.

• Communications for Statistical Applications and Methods
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• v.16 no.1
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• pp.85-102
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• 2009

This paper derives conversion formulas from yearly-based absolute rates of decrements to monthly-based rates of decrement due to cause J under fractional age distributions. Next, it suggests conversion formulas from monthly-based absolute rates of decrements to monthly-based rates of decrement due to cause j under fractional age distributions. In addition, it applies the conversion formulas including a dynamic lapse rate model to variable annuities. Some numerical examples are discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.469-474
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• 2020

This study explains the characteristics of micro-insurance based on the theoretical model of health insurance, such as the low demand of low-income people and the lower demand of higher risk aversion. In particular, these characteristics contradict the existing insurance theory which states that the lower the income, the higher the risk aversion, and the higher the demand for insurance. This study postulates a two-period model focusing on health insurance, contrary to a one-period model assumed in existing studies. As a result, first, we show that the decrease in income leads to a decrease in the preventive effort for illness. Second, we offer a model for micro-insurance in which the individual chooses a partial insurance under an actuarially fair insurance premium, while full insurance is optimal in existing studies. Third, we also show that the insurance demand decreases when the outlook for the future improves. Fourth, we finally show that the lack of trust and default risk of the insurer decrease the insurance demand as risk aversion increases.

• Korean Journal of Head & Neck Oncology
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• v.37 no.2
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• pp.19-24
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• 2021

Background/Objectives: The aim of this national population-based retrospective study was to analyze the status and treatment outcome in patients with hypopharyngeal cancer. Materials & Methods: Participants were included in the KNHIS national sample cohort who received a KNHIS health check-up in 2008 and 2009, and we followed these individuals until 2017. Patients were defined as having hypopharynx cancer if they had admissions records for hypopharynx cancer in their national health insurance data from 2010 to 2017. Results: The study cohort included 3,922 patients. According to our nationwide data, 3,533(90.1%) were male with a median age of 65.03±11.04 years at the time of diagnosis. Among parametric models for hypopharyngeal cancer prognosis, old age (Hazard ratio [HR]:1.92; 95% confidence interval[CI]:1.76-2.09), female (HR:0.77; 95% CI:0.66-0.89), and low socioeconomic status (HR:1.216; 95% CI:1.114-1.327) were significantly associated with survival. Compared with concurrent chemoradiotherapy, patients who received no treatment (HR, 1.88; 95% CI, 1.31-2.70), neoadjuvant chemotherapy followed by surgery (HR, 1.21; 95% CI, 1.04-1.41), and chemotherapy alone (HR, 1.16; 95% CI, 1.03-1.27) showed poor prognosis in hypopharyngeal cancer. Conclusion: Our data indicated that age, sex, and income were significant predictors of lifetime survival in patients with hypopharyngeal cancer. Treatment modalities were also associated with prognosis. The data have implications for treatment investigations and prevention strategies.

• Korean Circulation Journal
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• v.53 no.1
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• pp.17-30
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• 2023

Background and Objectives: To evaluate the impact of smoking in young adults on the risk of cardiovascular disease (CVD) and the clustering effect of behavioral risk factors such as smoking, obesity, and depression. Methods: A Korean nationwide population-based cohort of a total of 3,280,826 participants aged 20-39 years old who underwent 2 consecutive health examinations were included. They were followed up until the date of CVD (myocardial infarction [MI] or stroke), or December 2018 (median, 6 years). Results: Current smoking, early age of smoking initiation, and smoking intensity were associated with an increased risk of CVD incidence. Even after quitting smoking, the risk of MI was still high in quitters compared with non-smokers. Cigarette smoking, obesity, and depression were independently associated with a 1.3-1.7 times increased risk of CVD, and clustering of 2 or more of these behavioral risk factors was associated with a 2-3 times increased risk of CVD in young adults. Conclusions: In young adults, cigarette smoking was associated with the risk of CVD, and the clustering of 2 or more behavioral risk factors showed an additive risk of CVD.