• Journal of Chest Surgery
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• v.30 no.6
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• pp.607-612
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• 1997

Between March 1963, and December 1994, fifty-three patients with a ruptured aneurysm of sinus of Vasalva(RSV) were operated. The RSV originated from the right coronary sinus in 43 patients(81%), from the non coronary sinus in 7 patients(13%), and from combined sinuses in 2 patients. The RSV from the right coronary sinus mainly drained to the right ventricle(81.4%), and the RSV from the non coronary sinus mainly drained to the right atrium(71.4%). Recently, we are using patch to repair the RSV through a double approach. During the operation, concomitant . procedures were performed; 32 Patch repairs of VSD, 14 aortic valvuloplasty, 10 aortic valve replacement, 2 tricuspid valvuloplasty, and one Bentall's procedure. During the follow up period between 1 and 31 years(mean 8 years, 94% follow up), there were 2 late deaths and 14 late complications. Actuarial 10-year survival rate .was 95%, and 10-year actuarial freedom from late event was 53 %. Factor analysis revealed that the combined SBE is a risk factor of late event. Actuarial freedom from failure of aortic valvuloplasty was 55% at 9 years. Although surgical repair of RSV achieved excellent long term survival, aortic regurgitation and endocarditis revealed significant risk factor in long-term results. Therefore, more attention should be required in patients of RSV associated with aortic regurgitation or endocarditis.

• Radiation Oncology Journal
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• v.3 no.2
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• pp.123-129
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• 1985

A retrospective analysis was undertaken of 46 patients who were referred with squamous cell carcinoma of the esophagus during the period of March 1979 through October 1982, and who were treated by curative radiotherapy in the Department of Therapeutic Radiology Seoul National University Hospital. The overall two-year actuarial survival rate was $20\%$ Survival was analyzed with respect to the site of the cancer, its size, radiation dose, and degree of response. Patients with the best two-year survival rate are the ones who had the tumor no of more than 5cm in length $(39.3\%)$ or confined to the upper third of the esophagus $(29.5\%)$. An optimum radiation dose ranged from 1600 to 1700 rets. Patients to complete response had $42.4\%$ of two-year actuarial survival, but those to no response had $0\%$ of survival.

• Radiation Oncology Journal
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• v.6 no.2
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• pp.227-233
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• 1988

During the period between March 1979 and August 1986, 177 patients with carcinoma of the esophagus were treated with radiotherapy in the Department of Therapeutic Radiology, SNUH. Among these, 25 patients who had incomplete treatment were excluded. So a retrospective analysis was undertaken of 152 patients who were treated by curative radiotherapy. More than $80\%$ showed response: Complete remission $(22\%)$, partial remission $(63\%)$ and no response $(15\%)$. The overall two-year and five-year actuarial survival rate were $22.9\%\;and\;13.3\%$ respectively. Prognostic factor was analyzed by its site, size, T stage, and tumor response. Patients with the best five-year survival rate were those who had the tumor no more than 5cm in length $(17\%)$ or confined to the upper third of the esophagus $(20.6\%)$. Complete responders had $34.3\%$ of 5-year actuarial survival, but no responders had $0\%$ of survival.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.1013-1024
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• 1989

One hundred and seventy two patients of primary lung cancer, confirmed by tissue diagnosis at the Dept. of Thoracic and Cardiovascular Surgery in Korea University Hospital between June 1973 and August 1988, were evaluated and restaged with New International TNM classification, and the actuarial survival rate was obtained using Kaplan-Meier equation. The results of analysis were as follows. 1. Male to female ratio was 3.8:1, and prevalent age groups were sixth and seventh decades [76.4 %]. 2. The most common subjective symptom was cough [55.2 %], and 67.4 % of all patients were visited to hospital less than 6 months of symptoms. 3. Positive rates for tissue diagnosis were 100% in open chest or metastatic lymph node biopsy, 80 % in mediastinoscopic biopsy, 60 % in pleural biopsy, 59 % in pleural fluid cytology, 36% in bronchoscopic biopsy, and 22 % in sputum cytology. 4. The order of frequency of cell type was squamous cell carcinoma [53.0%], adenocarcinoma [22.0 %], small cell carcinoma [14.5 %], and so on. 5. Operability and resectability were 44% and 62% respectively, but they were improved recently. 6. Open and closure was done in 44 % of operated patients, uni or bilobectomy in 38 % and pneumonectomy in 24 %. 7. Overall operative mortality rate was 2.6 %. 8. The order of frequency of stage level was S3b [42.0 %], S3a [25.1 %], S1 [15.6%], and so on. 9. Distant metastasis, i.e. stage 4, was noted in 9.5 % of cases, and the sites of frequency were bone, brain, skin, and so on. 10. Actuarial survival rate was 1 year 48.2%, 2 year 36.9%, 3 year 31.2%, and 5 year 20.8%. According to above listed factors, 5 year survival rate was highest in squamous cell carcinoma, lobectomized cases, stage 1, NO in TNM system, and resectable cases. But T factor in TNM system and radiation therapy in nonresectable cases did not show statistical significance in life expectancy.

• The Korean Journal of Applied Statistics
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• v.26 no.6
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• pp.857-871
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• 2013

Export credit insurance is a policy tool for export growth. In the era of free trade under the governance of WTO, export credit insurance is still allowed as one of the few instruments to increase exports. This paper, using data on short-term export insurance contracts issued to foreign subsidiaries of Korean companies, calculates the expected loss per exposure by combining the effect of risk factors (credit rate of foreign importers, size of mother company, and payment period) on loss frequency and loss severity in different levels. We, applying generalized linear models (GLM), first fit loss frequency and loss severity to negative binomial and lognormal distribution, respectively, and then estimate the loss frequency rate per contract and the ratio of loss severity to coverage amount. Finally, we calculate the expected loss per exposure for each level of risk factors by combining these two rates. Based on the result of statistical analysis, we present the implication for the current premium rate of export insurance.

• Journal of the Korean Data and Information Science Society
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• v.27 no.1
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• pp.75-89
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• 2016

This study suggests both modification reserve ratio and cover rate for expenditure as new finance evaluation indicators. Firstly, modification reserve ratio is an evaluation indicator which shows how long can the accumulated reserves at the beginning of the year afford future benefit expenditure. Modification reserve ratio has an advantage both to present what the scale of annual accumulated reserves means and to know the exhaustion speed of accumulated fund through analyzing the trend of modification fund ratio. Secondly, this research classifies resources for expenditures as premium income and reserves, thereafter, presents cover rate for expenditure as finance evaluation indicator. We can know how premium income and reserves can cover future expenditure during the evaluation period, and how deficient are resources through these indices. The researcher anticipates this research to contribute to policy researches for financial stabilization of the national pension scheme.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1315-1331
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• 2014

Replacement rates which shows the ratio of retirement income relative to preretirement income is used for a valuable evaluation measures while discussing social security benefit levels or the adequacy of retirement income. However, replacement rates has been only used for an index for evaluating benefit level at the time of retirement or specific retirement period in advanced research projects. This article analyzes how much the uncertainty of survival has an influence on retirement income, and shows replacement rates in conformity with the period of survival as an index. The researchers named this index lifetime income replacement rates. Analysis based on this index shows both life replacement income rates of 38.3% in men's case and of 41.1% in women's case while enrolled for 20years in three pension plans - national pension, retirement pension and individual annuity.

• Communications for Statistical Applications and Methods
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• v.25 no.5
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• pp.569-575
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• 2018

Pareto distribution is important to analyze data in actuarial sciences, reliability, finance, and climatology. In general, unknown parameters of the Pareto distribution are estimated based on the maximum likelihood method that may yield inadequate inference results for small sample sizes and high percent censored data. In this paper, a new approach based on the regression framework is proposed to estimate unknown parameters of the Pareto distribution under the progressive Type-II censoring scheme. The proposed method provides a new regression type estimator that employs the spacings of exponential progressive Type-II censored samples. In addition, the provided estimator is a consistent estimator with superior performance compared to maximum likelihood estimators in terms of the mean squared error and bias. The validity of the proposed method is assessed through Monte Carlo simulations and real data analysis.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7117-7120
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• 2013

Background: This study hypothesized living in a poor neighborhood decreased the cause specific survival in individuals suffering from carcinoid carcinomas. Surveillance, Epidemiology and End Results (SEER) carcinoid carcinoma data were used to identify potential socioeconomic disparities in outcome. Materials and Methods: This study analyzed socioeconomic, staging and treatment factors available in the SEER database for carcinoid carcinomas. The Kaplan-Meier method was used to analyze time to events and the Kolmogorov-Smirnov test to compare survival curves. The Cox proportional hazard method was employed for multivariate analysis. Areas under the receiver operating characteristic curves (ROCs) were computed to screen the predictors for further analysis. Results: There were 38,546 patients diagnosed from 1973 to 2009 included in this study. The mean follow up time (S.D.) was 68.1 (70.7) months. SEER stage was the most predictive factor of outcome (ROC area of 0.79). 16.4% of patients were un-staged. Race/ethnicity, rural urban residence and county level family income were significant predictors of cause specific survival on multivariate analysis, these accounting for about 5% of the difference in actuarial cause specific survival at 20 years of follow up. Conclusions: This study found poorer cause specific survival of carcinoid carcinomas of individuals living in poor and rural neighborhoods.

• The Journal of Society for e-Business Studies
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• v.22 no.1
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• pp.15-35
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• 2017

The method of weighted sum of evaluation using AHP is widely used in feasibility analysis and alternative selection. Final scores are given in forms of weighted sums and the alternative with largest score is selected. With two alternatives, as in feasibility analysis, the final score greater than 0.5 gives the selection but there remains a question that how large is large enough. KDI suggested a concept of 'grey area' where scores are between 0.45 and 0.55 in which decisions are to be made with caution, but it lacks theoretical background. Statistical testing was introduced to answer the question in some studies. It was assumed some kinds of probability distribution, but did not give the validity on them. We examine the various cases of weighted sum of evaluation score and show why the statistical testing has to be introduced. We suggest a non-parametric testing procedure which does not assume a specific distribution. A case study is conducted to analyze the validity of our suggested testing procedure. We conclude our study with remarks on the implication of analysis and the future way of research development.