• Communications for Statistical Applications and Methods
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• v.4 no.2
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• pp.491-496
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• 1997

For the survival data analysis of no covariate the discount survival model is proposed to estimate the time-varying hazard rate and the survival function recursively. In comparison with the covariate case it provide the distributionally explicit evolution of hazard rate between time intervals under the assumption of a conjugate gamma distribution. Also forecasting of the hazard rate in the next time interval is suggested, which leads to the forcecasted survival function.

• Journal of Chest Surgery
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• v.18 no.3
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• pp.506-512
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• 1985

We have experienced 120 non-small cell primary carcinomas of the lung between June, 1974 and December, 1984, at Seoul National University Hospital. They were 107 males and 13 females. 95% of all were ranged from 40 years to 69 years of age with 56 years of mean age. They were composed of 70 [66.7%] squamous cell ca., 20 [19%] adenoca., 6 [5.7%] undifferentiated large cell ca., 4 [3.8%] undifferentiated small cell ca., and 5 [4.8%] mixed adenosquamous cell ca. 41 [36%] and 35 [30.7%] patients have received pneumonectomies and lobectomies with a 66.7% resectability rate. Of the 36 stage I and 21 stage II patients, 56 were resectable but only 20 [31.7%] of the 63 stage III patients were resectable. This informed us the significance of the stage of the disease at the time of operation. The actuarial survival rate in 70 patients was as follow: 1, 3, 5 year survival rate of the patients in stage I were 80%, 80%, and 60% respectively. Both 1, 3 year survival rate of patients in stage II were 84%. But 1, 2, 3 year survival rate of patients in stage III were 40%, 11%, and 5% respectively. By dividing the patients in stage III into resectable group and nonresectable one, both 1, 2 year survival rate of the former were 37% and those of the latter were 42% and 7%. According to the cell type of the cancer, 1, 3, 5 year survival rate of the squamous cell ca. were 63%, 40%, and 26% respectively. 1, 3 year survival rate of the adenoca. were 43% and 34%. Hospital death were only 2 cases with a 1.7% operative mortality rate. We had acceptable long-term survival rate and have convinced the necessity and hope of the early detection and resection of the lung carcinoma.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.6
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• pp.537-543
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• 2010

Purpose: The objective of this study is to evaluate the survival rate and influencing factors. Patients and Methods: We studied 104 patients who were diagnosed for squamous cell carcinoma of tongue and received curative treatment in oral oncology clinic of National Cancer Center from June 2001 to December 2009. Results: We found the following results. 1. The overall 5-year survival rate of tongue cancer was 67.0% and there was no significant statistical difference between male and female. 2. A lower survival rate was shown in patients under 40 years (42.2%) than over 40 years (75.5%)(P < 0.05). 3. 5-year survival rates of patients with tongue cancer classified by pTNM classification were 87.4% in early stage and 43.3% (P < 0.05). 4. A higher survival rate was seen in patients without cervical lymph node metastasis (82.0% > 44.1%)(P < 0.05). 5. A higher survival rate was seen in patients of tongue cancer with higher differenciation grade (P < 0.05). 6. It is well known that drinking and smoking have great influence on the survival rate of patients of squamous cell carcinoma of tongue. But these was no statistical significance. Conclusion: The overall 5-year survival rate of tongue cancer was 67.0% and it was mostly influenced by factors like age, pTNM stage, cervical lymph node metastasis, differentiation of cancer cell etc.

• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.29.1-29.11
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• 2021

Objectives: This study was conducted to compare the post-fracture survival rate of endodontically treated molar endodontically treated teeth (molar ETT) restored with resin composites or crowns and to identify potential risk factors, using a retrospective cohort design. Materials and Methods: Dental records of molar ETT with crowns or composite restorations (recall period, 2015-2019) were collected based on inclusion and exclusion criteria. The incidence of unrestorable fractures was identified, and molar ETT were classified according to survival. Information on potential risk factors was collected. Survival rates and potential risk factors were analyzed using the Kaplan-Meier log-rank test and Cox regression model. Results: The overall survival rate of molar ETT was 87% (mean recall period, 31.73 ± 17.56 months). The survival rates of molar ETT restored with composites and crowns were 81.6% and 92.7%, reflecting a significant difference (p < 0.05). However, ETT restored with composites showed a 100% survival rate if only 1 surface was lost, which was comparable to the survival rate of ETT with crowns. The survival rates of ETT with composites and crowns were significantly different (97.6% vs. 83.7%) in the short-term (12-24 months), but not in the long-term (> 24 months) (87.8% vs. 79.5%). Conclusions: The survival rate from fracture was higher for molar ETT restored with crowns was higher than for ETT restored with composites, especially in the first 2 years after restoration. Molar ETT with limited tooth structure loss only on the occlusal surface could be successfully restored with composite restorations.

• Journal of Korean Neurosurgical Society
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• v.60 no.6
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• pp.661-666
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• 2017

Objective : Atypical meningioma is rare tumor and there is no accurate guide line for optimal treatment. This retrospective study analyzed the prognostic factors, the effect of different methods of treatments and the behavior of atypical meningioma. Methods : Thirty six patients were diagnosed as atypical meningioma, among 273 patients who were given a diagnosis of meningioma in the period of 2002 to 2015. Age, gender, tumor location, Ki 67, Simpson grade and treatment received were analyzed. We studied the correlation between these factors with recurrence, overall survival rate and progression free survival. Results : Median overall survival time and progression free survival time are 60 and 53 (months). Better survival rate was observed for patients less than 50 years old but with no statistical significance (p=0.322). And patients with total resection compared with subtotal resection also showed better survival rate but no statistical significance (p=0.744). Patients with a tumor located in skull base compared with patients with a tumor located in brain convexity and parasagittal showed better progression free survival (p=0.048). Total resection is associated with longer progression-free survival than incomplete resection (p=0.018). Conclusion : We confirmed that Simpson grade was significant factor for statistically affect to progression free survival in univariate analysis. In case of skull base atypical tumor, it is analyzed that it has more recurrence than tumor located elsewhere. Overall survival was not affected statistically by patient age, gender, tumor location, Ki 67, Simpson grade and treatment received in this study.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.5
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• pp.207-216
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• 2013

Objectives: The purpose of this study is to analyze clinical impact factors on the survival rate, and to acquire basic clinical data for the diagnosis of oral cancer, for a determination of the treatment plan with long-term survival in oral cancer patients. Materials and Methods: Through a retrospective review of the medical records, the factors for long-term survival rate were analyzed. Thirty-seven patients, among patient database with oral cancer treated in the Department of Oral and Maxillofacial Surgery at Pusan National University Hospital within a period from March 1998 to March 2008, were selected within the study criteria and were followed-up for more than 5 years. The analyzed factors were gender, age, drinking, smoking, primary tumor site, type of cancer, TNM stage, recurrence of affected region, and metastasis of cervical lymph node. The 5-year survival rate on the impact factors was calculated statistically using the Kaplan-Meier method. Results: By classification of clinical TNM at the 1st visit, there were 11 (29.7%) cases for stage I, 11 (29.7%) cases for stage II, 3 (8.1%) cases for stage III, and 12 (32.5%) cases for stage IV. The 5-year survival rate of total oral cancer patients after the operation were 75.7%, pathological TNM stage related 5-year survival rate were as follows: stage I 90.0%, stage II 81.8%, stage III 100% and stage IV 45.5%; in which the survival rate difference by each stage was significantly observed. The recurrence of cervical lymph node was the significant impact factor for the survival rate, because only 30.0% the survival rate in recurrent cases existed. During the follow-up, there were 15 (40.5%) patients with confirmed recurrence, and the 5-year survival rate of these patients was decreased as 46.7%. Conclusion: The classification of clinical and pathological TNM stage, local recurrence after surgery, and metastasis of cervical lymph node after surgery were analyzed as the 3 most significant factors.

• Biomedical Science Letters
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• v.25 no.1
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• pp.32-39
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• 2019

Conventional high-flux hemodialysis (HD) is not as good as normal kidney function. Morbidity and mortality rates of patients receiving HD are still very high. To increase mid-to-large molecule clearance by combining diffusion and convection, on-line hemodiafiltration (HDF) is required. The objective of this study was to compare long-term survival rate of patients treated with on-line HDF to those who received conventional high-flux HD by reviewing data from Chonnam National University Hospital (CNUH). We selected patients who attended the 'CUNH dialysis center' and agreed to participate in the study. Overall, 40 patients with ESRD switched from high flux HD to on-line HDF or started on-line HDF from August 2007 to December 2009. Additionally, a total of 42 patients receiving conventional high-flux HD during the same period were enrolled. We then reviewed long-term survival rate of patients receiving on-line HDF over the next seven years. When we compared survival rates for seven years, the survival rate of the group receiving on-line HDF was 65% (26/40) while that of the group receiving the conventional high-flux HD was 54.8% (23/42). Although the number of patients was small to see survival difference clearly by one specific dialysis modality, there was somewhat difference in survival rate between the two groups. Indicators such as anemia, calcium-phosphate metabolism, nutritional status, treatment adequacy, and hospitalization were also improved in the group receiving HDF. Overall, results of our study showed beneficial effects of on-line HDF on clinical outcomes and survival in chronic HD patients.

• Journal of radiological science and technology
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• v.37 no.1
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• pp.21-28
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• 2014

Cultured pancreatic beta cells and nerve cells, it is given normal condition of 10% FBS (fetal bovine serum), 11.1 mM glucose and hyperglycemia codition of 1% FBS, 30 mM glucose. For low LET X-ray irradiated with 0.5 Gy/hr dose-rate(total dose: 0.5 to 5 Gy). Survival rates were measured by MTT assay. When non irradiated, differentiated in the pancreatic beta cells experiment is hyperglycemia conditions survival rate compared to normal conditions survival rate seemed a small reduction. However increasing the total dose of X-ray, the survival rate of normal conditions decreased slightly compared to the survival rate of hyperglycemia conditions, the synergistic effect was drastically reduced. When non irradiated, undifferentiated in the nerve cells experiment is hyperglycemia conditions survival rate compared to normal conditions survival rate seemed a large reduction. As the cumulative dose of X-ray normal conditions and hyperglycemia were all relatively rapid cell death. But the rate of decreased survivals by almost parallel to the reduction proceed and it didn't show synergistic effect.

• Journal of Periodontal and Implant Science
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• v.39 no.4
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• pp.413-423
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• 2009

Purpose: The presented study aims to evaluate the effects of osteoporosis on dental implants by analyzing a 12-year cumulative survival rate of implants placed in patients with osteoporosis. Methods: 37 patients with history of osteoporosis were selected from a pool of dental implant patients treated at the Department of Periodontology in Yonsei University Hospital between 1993 and 2007. The cumulative survival rate is quantified using data collected from 164 placed implants in the selected 37 patients. Results: 3 out of the 164 implants failed and the cumulative survival rate was observed at 95.1%. The survival rates of the implants according to patients' age were 97.41% (<60) and 100% ($60\leq$). The lower survival rate was directly proportional to younger age, and this relationship is statistically significant (P<0.05). The survival rates of implants according to diagnostic criteria were 95.45% (osteopenia) and 98.59% (osteoporosis; 2 out of 142 implants placed in osteoporosis patients failed). The difference in the two survival rates is statistically significant (P<0.05). The survival rates according to the region of implants do not have statistically significant difference. The survival rates according to the different length and diameter of the implants do not have statistically significant difference. The survival rates of implants accompanied and not accompanied by bone augmentation were 92.11% and 100%, respectively. The difference in the two survival rates is statistically significant (P<0.05). The survival rates of implants placed in patients with and without history of medication for osteoporosis treatment are 96.67% and 99.04%, respectively. The difference in the two survival rates is statistically significant (P<0.05). Conclusions: A high cumulative survival rate of dental implants, similar to one found in non-osteoporosis patients, is observed in osteoporosis patients, indicating the possibility that placing dental implants on patients with osteoporosis can be considered with high treatment predictability.

• Journal of Korean Neurosurgical Society
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• v.53 no.4
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• pp.228-234
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• 2013

Objective : We have limited understanding on the presentation and survival of primary spinal sarcomas. The survival, recurrence rate, and related prognostic factors were investigated after treatment for primary sarcomas of the spine. Methods : Retrospective analysis of medical records and radiological data was done for 29 patients in whom treatment was performed due to primary sarcoma of the spine from 2000 to 2010. As for treatment method, non-radical operation, radiation therapy, and chemotherapy were simultaneously or sequentially combined. Overall survival (OS), progression free survival (PFS), ambulatory function, and pain status were analyzed. In addition, factors affecting survival and recurrence were analyzed : age (${\leq}42$ or ${\geq}43$), gender, tumor histologic type, lesion location (mobile spine or rigid spine), weakness at diagnosis, pain at diagnosis, ambulation at diagnosis, initial treatment, radiation therapy, kind of irradiation, surgery, chemotherapy and distant metastasis. Results : Median OS was 60 months, the recurrence rate was 79.3% and median PFS was 26 months. Patients with distant metastasis showed significantly shorter survival than those without metastasis. No factors were found to be significant relating to recurrence. Prognostic factor associated with walking ability was the presence of weakness at diagnosis. Conclusion : Primary spinal sarcomas are difficult to cure and show high recurrence rate. However, the development of new treatment methods is improving survival.