• The Journal of Advanced Prosthodontics
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• v.9 no.3
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• pp.195-199
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• 2017

PURPOSE. The objective of this study was to determine the cumulative survival rate (CSR) and associated risk factors of Implantium implants by retrospective clinical study. MATERIALS AND METHODS. Patients who received Implantium implants (Dentium Co., Seoul, Korea) at Korea University Guro Hospital from 2004 to 2011 were included. The period between the first surgery and the last hospital visit until December 2015 was set as the observation period for this study. Clinical and radiographic data were collected from patient records, including all complications observed during the follow-up period. Kaplan-Meier analysis was performed to examine CSR. Multiple Cox proportional hazard model was employed to assess the associations between potential risk factors and CSR. RESULTS. A total of 370 implants were placed in 121 patients (mean age, 56.1 years; range, 19 to 75 years). Of the 370 implants, 13 failed, including 7 implants that were lost before loading. The 10-year cumulative survival rate of implants was 94.8%. The multiple Cox proportional hazard model revealed that significant risk factor of implant failure were smoking and maxillary implant (P<.05). CONCLUSION. The 10-year CSR of Implantium implants was 94.8%. Risk factors of implant failure were smoking and maxillary implant.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.2
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• pp.68-75
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• 2014

Objectives: This study was performed to analyze the cumulative survival rate of Osstem implants (Osstem Implant Co., Ltd.) over a seven-year period. Materials and Methods: A total of 105 patients who had 467 Osstem implants that were placed at the Section of Dentistry, Seoul National University Bundang Hospital (Seongnam, Korea) from June 2003 through December 2005 were analyzed. The life table method and a cross-tubulation analysis, log rank test were used to evaluate the survival curve and the influence that the prognostic factors. The prognostic factors, i.e., age and gender of patients, diameter and length, type of implants, bone graft history and loading time were determined with a Cox proportional hazard model based on logistic regression analysis. Results: The seven-year cumulative survival rate of Osstem implants was 95.37%. The Cox proportional hazard model revealed that the following factors had a significant influence on survival rate; increased diameter, reduced prosthetic loading period and performance of bone grafting. Conclusion: The osstem implants showed satisfactory results over the seven-year study period.

• Journal of Labour Economics
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• v.26 no.3
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• pp.181-207
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• 2003

The purpose of this study was to conduct a dynamic analysis of married women's return to the workforce following first childbirth. We have based our investigation on the data compiled by the KLIPS, where the workforce performance is the focal point of it's research, and by these materials, this study has analyzed the aspects of the factors that decide post-childbirth return to the workforce. We have applied the Cox Regression Hazard Model, where corroborative evidence are statistically applied. The following are the conclusions that were derived from this research: First, according to the study, academic background is a vital factor in reducing the gap and time of women's return to the workforce. Second, whether having active child-care after giving birth or not doubles the chances of women returning to the workforce. Third, if the pre-birth employment form was a wage-work and the rate of returning to the workforce was lower than the non-wage, relatively speaking, this reflects that the non-wage form of work, which provides a better possibility to return to the workforce after giving birth, could be another way to prevent women's career discontinuation.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.71-82
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• 2012

This study analyzed factors affecting daily travel times at each stage of commuters' life cycle. In this study, travel times were dealt with in the context of trip chain. That is, the travel time was defined as the total amount of time commuters had spent to move for daily activities from leaving to coming back home. A commuter's life cycle was divided into 6 stages on a basis of both householder's age and family type: i.e., the unmarried youth period, the family forming period, the children education period, the children youth period, the children independence period, and the aged period. Variables such as commuting times, home-based trip cycle recurrences, and the number of stops differed for each stage of life cycle, the latter of which represents how many places a commuter dropped by during a trip cycle. Several factors were found to affect commuting times at each stage of life cycle as a result of applying a Cox proportional hazard model. The empirical study was conducted using 2010' household travel survey data collected from Gyeonggi-do.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3255-3261
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• 2013

Background: The efficacy of erlotinib is controversial in patients with unknown EGFR mutational status. The aim of this study was to identify the clinicopathological factors that are predictive of erlotinob treatment outcomes for NSCLC patients with unknown EGFR mutational status. Materials and Methods: A retrospective analysis of 109 patients with advanced NSCLC who had previously failed at least one line of chemotherapy and received subsequent treatment with erlotinib (150 mg/day orally) was performed. A Cox proportional hazard model for univariate and multivariate analyses was used to identify the baseline clinical parameters correlating with treatment outcome, expressed in terms of hazard ratios (HRs) and 95% confidence intervals. Results: The median treatment duration was 15 weeks (range, 4-184). The disease control rate was 55%, including disease stability for ${\geq}3$ months for 40% of the patients. Median progression-free survival and median overall survival (OS) were 4.2 and 8.5 months, respectively. The Cox model indicated that an Eastern Cooperative Oncology Group performance status (ECOG PS) ${\geq}2$ (HR 3.82; p<0.001), presence of intra-abdominal metastasis (HR 3.42; p=0.002), 2 or more prior chemotherapy regimens (HR 2.29; p=0.021), and weight loss >5% (HR 2.05; p=0.034) were independent adverse prognostic factors for OS in NSCLC patients treated with erlotinib. Conclusions: This study suggests that NSCLC patients should be enrolled in erlotinib treatment after a first round of unsuccessful chemotherapy to improve treatment success, during which they should be monitored for intra-abdominal metastasis and weight loss.

• Korea journal of population studies
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• v.29 no.3
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• pp.159-188
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• 2006

This study attempts to create a longitudinal dataset by linking tdata on the identical individuals across the monthly sample household management lists of the Economically Active Population Survey(EAPS) and the Household Income and Expenditure Survey(HIES). Using the data constructed through such process, the study also tryies to analyze the duration of longitudinal responses and the characteristics of nonrespondents. Between 1998 and 2002, longitudinal response rates had declined to 46% of total EAPS and 34% of total HIES. The fact that nonresponse was not a random phenomenon leads to concerns about the representativeness of the remaining sample. Using Cox's proportional hazard model the study revealed that the duration of longitudinal responses is affected by the ownership of house and the age of the respondent.

• Journal of Preventive Medicine and Public Health
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• v.45 no.1
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• pp.14-20
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• 2012

Objectives: The aim of this study was to evaluate and quantify the risk of both individual and combined health behaviors on premature mortality in middle aged men in Korea. Methods: In total, 14 533 male subjects 40 to 59 years of age were recruited. At enrollment, subjects completed a baseline questionnaire, which included information about socio-demographic factors, past medical history, and life style. During the follow-up period from 1993 to 2008, we identified 990 all-cause premature deaths using national death certificates. A Cox proportional hazard regression model was used to estimate the hazard ratio (HR) of each health risk behavior, which included smoking, drinking, physical inactivity, and lack of sleep hours. Using the Cox model, each health behavior was assigned a risk score proportional to its regression coefficient value. Health risk scores were calculated for each patient and the HR of all-cause premature mortality was calculated according to risk score. Results: Current smoking and drinking, high body mass index, less sleep hours, and less education were significantly associated with all-cause premature mortality, while regular exercise was associated with a reduced risk. When combined by health risk score, there was a strong trend for increased mortality risk with increased score (p-trend < 0.01). When compared with the 1-9 score group, HRs of the 10-19 and 20-28 score groups were 2.58 (95% confidence intervals [CIs], 2.19 to 3.03) and 7.09 (95% CIs, 5.21 to 9.66), respectively. Conclusions: Modifiable risk factors, such as smoking, drinking, and regular exercise, have considerable impact on premature mortality and should be assessed in combination.

• The Journal of the Korea Contents Association
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• v.19 no.5
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• pp.287-295
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• 2019

This study was conducted to analyze firm survival rate and impact factors of survival of Foreign-invested Companies in Korea which is between 2006 and 2017. An empirical analysis of the survival factors of firms used explanatory variables such as characteristics of the and 3 firm dummy and 2 firm factors, financial variables of 3 profitability and 3 stability factors. The Kaplan-Meier method was chosen to perform analyses on the survival rates, Cox Proportional Hazard Model took to conduct on the impact factors. As a result of the impact factors of Foreign-invested Companies survival, Ownership (OS), Labour (NE ) of characteristics of the firm had positive effects. The Gross Sales Profit (GSP), Net Profit (NP ) and Operating Profit (OP ) of the financial characteristics had a positive effect. Additional Asset (LA ) had positive effects and Capital (LC), Debt (LB ) had a negative effect. Other factors did not produce significant results.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.692-700
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• 2022

This study was conducted to analyze firms' death rate and impact factors on the death of Foreign-invested Companies in Korea which is between 20013 and 2017. Cox Proportional Hazard Model took to conduct on the death impact factors, such as 2 characteristics factors of the firm, and 4 financial characteristics variables, variables, and 4 profitability factors. As a result of the impact factors of Foreign-invested Companies' death the Labour(NE) variables of characteristics firm had negative effects. And the Debt(LB), Operating Profit (OP), and Sales Profit (SP) of the financial characteristics had a negative effect. Other factors did not produce significant results. As a result of an empirically comparative analysis of the mortality rate of foreign-invested companies by the Kaplan-Meier method, it was analyzed that fully owned companies and large enterprises had lower extinction risk and greater sustainable management potential than joint ventures or SMEs.

• Korean small business review
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• v.43 no.3
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• pp.1-20
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• 2021

The survival period according to technological capability was analyzed for about 22,500 innovative SMEs in the service industry. The survival period was defined as the occurrence of overdue and default, and the technological capability was divided into two clusters. As a result of estimating the survival period according to technological capability through Kaplan-Meier analysis, it was confirmed that the estimated survival period of T1-T4 grade service innovative SMEs was significantly greater in both overdue and default. As a result of the analysis of the Cox proportional hazard model applying the control variable, it was confirmed that the higher technological capability, the lower the risk in the group of start-up companies. However, in the group of non-start-up companies the technological capability did not significantly affect the survival period, and the influence of the variables related to the size of the company was found to increase. Therefore, the technological capability is meaningful as additional information that has a significant effect on the survival period of innovative SMEs in the start-up companies group of service industry. In addition, it was concluded that it is necessary to reflect the technological capability when establishing the SME support and promotion policy of the start-up companies group in the service industry.