• International Journal of Reliability and Applications
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• 제2권1호
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• pp.1-26
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• 2001

The purpose of this paper is to introduce a proportional reversed hazard rate model, in contrast to the celebrated proportional hazard model, and study some of its structural properties. Some criteria of ageing are presented and the inheritance of the ageing notions (of the base line distribution) by the proposed model are studied. Two important data sets are analyzed: one uncensored and the other having some censored observations. In both cases, the confidence bands for the failure rate and survival function are investigated. In one case the failure rate is bathtub shaped and in the other it is upside bath tub shaped and thus the failure rates are non-monotonic even though the baseline failure rate is monotonic. In addition, the estimates of the turning points of the failure rates are provided.

• Journal of Periodontal and Implant Science
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• 제38권3호
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• pp.445-452
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• 2008

Purpose: The purpose of this study was comparison of survival rate of implant as two sinus elevation techniques and when window opening procedure had done it was comparison of survival rate of implant between the procedure of implantation after 6 month of sinus elevation to allow healing period and that of implantation with sinus elevation simultaneously. Material and Methods: All 79 of patients treated at DanKook University Dental Hospital Dept. of Periodontics for 164 implantation of maxillary posterior edentulous area with sinus elevation. Sinus elevation technique was divided of the technique : Osteotome technique and window opening technique. Result: 14 implants among 96 implants was failed implants of using osteotome for sinus elevation whereas one implant of 68 implants was failed of using window opening technique. Conclusion: Window opening technique had higher survival rate than osteotome technique. In case of window opening, there was no significant difference of immediate implantation and delayed implantation.

• Journal of Periodontal and Implant Science
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• 제39권3호
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• pp.311-320
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• 2009

Purpose: The aim of the present study was to analyze 7-year cumulative survival rate (CSR, %) of dental implants in the controlled diabetic patients and to evaluate the influence of the position, diameter and length of fixture, bone quality, age, gender and the method of maxillary sinus elevation on the survival rate. Methods: The data of 342 placed implants in the 104 diabetic patients collected between 1995 and 2007 at the Department of Periodontology in Yonsei University Hospital were analyzed. Results: Seven-year CSR of the 342 dental implants in the 104 controlled diabetic patients was 96.5%. The survival rates of the placed implants according the position have no statistically significant difference. The survival rates according to the length or diameter of the fixtures have no statistically significant difference. The survival rates according to the bone quality were 100% (Type I), 97.1% (Type II), 97.7% (Type III) and 85.7%(Type IV). The difference between the survival rate of Type I, II and III and that of Type IV was statistically significant. The survival rates according to patient gender were 96.8% (male), 95.5% (female). The survival rates according to patient age were 100% (${\leq}59$), 93.8% (${\geq}60$). The survival rates according to the method of sinus elevation in the maxillary posterior area were 96.8% (without sinus elevation), 92.9% (lateral approach) and 89.8% (crestal approach). Conclusions: Dental implants can be used successfully in the controlled diabetic patients. In case of upper posterior region which has poor bone density and older patients, the implant treatment should be more properly planed, executed, and followed-up.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.36.1-36.8
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• 2019

Background: This study aims to examine the outcome of simultaneous maxillary sinus lifting, bone grafting, and vertical ridge augmentation through retrospective studies. Methods: From 2005 to 2010, patients with exhibited severe alveolar bone loss received simultaneous sinus lifting, bone grafting, and vertical ridge augmentations were selected. Fifteen patients who visited in Seoul National University Bundang Hospital were analyzed according to clinical records and radiography. Postoperative complications; success and survival rate of implants; complications of prosthesis; implant stability quotient (ISQ); vertical resorption of grafted bone after 1, 2, and 3 years after surgery; and final observation and marginal bone loss were evaluated. Results: The average age of the patients was 54.2 years. Among the 33 implants, six failed to survive and succeed, resulting in an 81.8% survival rate and an 81.8% success rate. Postoperative complications were characterized by eight cases of ecchymosis, four cases of exposure of the titanium mesh or membrane, three cases of periimplantitis, three cases of hematoma, two cases of sinusitis, two cases of fixture fracture, one case of bleeding, one case of numbness, one case of trismus, and one case of fixture loss. Prosthetic complications involved two instances of screw loosening, one case of abutment fracture, and one case of food impaction. Resorption of grafted bone material was 0.23 mm after 1 year, 0.47 mm after 2 years, 0.41 mm after 3 years, and 0.37 mm at the final observation. Loss of marginal bone was 0.12 mm after 1 year, and 0.20 mm at final observation. Conclusions: When sinus lifting, bone grafting, and vertical ridge augmentation were performed simultaneously, postoperative complications increased, and survival rates were lower. For positive long-term prognosis, it is recommended that a sufficient recovery period be needed before implant placement to ensure good bone formation, and implant placement be delayed.

• Archives of Plastic Surgery
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• 제36권4호
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• pp.411-416
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• 2009

Purpose: Malignant melanoma is recognized as the most serious skin cancer. We examined anatomical distribution and 5 - year survival rate of each stage of malignant melanoma on lower leg. Methods: We retrospectively analyzed the medical records of 91 patients(46 males and 45 females) with malignant melanoma on lower leg from 1985 to 2008. Age, sex, anatomical distribution and 5 - year survival rates of each stage of malignant melanoma on lower leg were investigated. Also, 5 - year survival rates of each stage and invasion depth of malignant melanoma on heel pad were investigated. Results: On lower leg, most frequently 32 cases(35.1%) occurred on heel pad, 27 cases(29.7%) occurred on dorsum of foot, 18 cases(19.8%) in toe and 14 cases(15.4%) on others in lower leg. We used the excision margin as 3 ~ 5 cm. After wide excision, in stage III, IV, the patients underwent the immunologic / chemo - therapy. The incidences of each stage were 22 cases(24.2%) in stage I, 47(51.6%) in II, 17(18.7%) in III and 5(5.5%) in IV. The 5 - year survival rates of each stage were 85%, 53.2%, 47.1% and 40%. On heel pad, the incidences of each stage were 5 cases(15.6%) in stage I, 19 cases(59.4%) in II, 7 cases(21.9%) in III and 1 case(3.1%) in IV. The 5 - year survival rates of each stage were 80%, 63.2%, 42.9% and 100%. On heel pad, incidence of local recurrence was 2 and 5 - year survival rate of this case was 100%. And systemic recurrence was 9 and 5 - year survival rate of this case was 55.6%. Conclusion: The 5 - year survival rate of malignant melanoma on heel pad was higher than previous study. To maintain the weight - bearing function of foot, we recommend the active reconstructive surgery for heel pad reconstruction after wide excision of heel pad malignant melanoma.

• Journal of Chest Surgery
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• 제23권1호
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• pp.122-127
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• 1990

The management of esophageal carcinoma continues to be a difficult problem with most surgically treated patients under-going extensive operative procedures for palliation only. Although recent advances in preoperative and postoperative care have decreased the operative mortality rate, survival has not changed significantly. Twenty five patients with esophageal carcinoma who were treated with operative intervention at the Department of Thoracic and Cardiovascular Surgery in Kyung Hee University Hospital between January, 1980 and December, 1987 had been evaluated clinical manifestation and operative results. The stamm typed feeding gastrostomy and Celestin tube insertion were performed for the cases of nonresectable esophageal cancer. Also 14 cases with esophagogastrostomy and are case with esophagocologastrostomy were performed for the resectable cases. Two deaths with resectable cases occurred within 30days of operation, a hospital death rate of 8 per cent. There were significant differences in the survival rate between T.N.M. staging I, II, and III, IV group after the resection of the esophageal cancer. The former group revealed higher one year survival rate than the later group. [p< 0.05]. In conclusion, the clinical manifestations and operative results were similar to the western ones and the postoperative survival rate was very poor. So, the earlier the operation of the esophageal cancer was done, the better result will be achieved. To defect the early esophageal cancer; routine esophagoscopy should be recommended.

• Journal of the Korean Statistical Society
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• 제33권2호
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• pp.191-202
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• 2004

The paper considers nonparametric empirical Bayes estimation of residual survival function at age t using a Dirichlet process prior V(a). Empirical Bayes estimators are proposed for the case where both the function ${\alpha}$(0, $\chi$] and the size a(R$\^$+/) are unknown. It is shown that the proposed empirical Bayes estimators are asymptotically optimal at a rate n$\^$-1/, where n is the number of past data available for the present estimation problem. Therefore, the result of Lahiri and Park (1988) in which a(R$\^$+/) is assumed to be known and a rate n$\^$-1/ is achieved, is extended to a(R$\^$+/) unknown case.

• Radiation Oncology Journal
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• 제11권1호
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• pp.103-108
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• 1993

Among the patients with rectal cancer who entered Yonsei University Hospital for management from Jan. 1980 to Dec. 1990, we selected 23 subjects who were received surgical resection of tumor in rectum, and who proved to have liver metastasis during the diagnostic work-up, at the time of the operation, or within 3 months after starting definitive treatment. With those subjects, we investigated the role of radiation therapy by comparison of the treatment results of the patients without radiation therapy (S group) with those of the patients with radiation therapy to the primary site (S+R group). The local control rates of S group and S+R group were $64{\%}$ and $89{\%}$, and 2-year survival rates were $50{\%}$ and $78{\%}$, respectively. Although there was not statistically meaningful difference, local control rate and 2-year survival rate were higher in the group with radiation therapy to primary site than that without radiation therapy. The 2-year survival rates of the case with resection of the liver and the case without it were $63.6{\%}$ and $58.3{\%}$ respectively, which was not statistically significant. Also, the 2-year survival rate of the case with sustained local control was higher than that of the case with local failure, which was statistically significant ($76.5{\%}$ and $16.7{\%}$, p<0.005). From the above results, it is thought that radiation therapy to the primary site might improve the local control rate even in the patients with liver metastasis, which seems to be correlated to the higher survival rate.

• 한국수정란이식학회지
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• 제8권1호
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• pp.1-7
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• 1993

This study was carried out to investigate the survival rates of late mouse molulae frozen in the state of vitrification and then thawed after equilibrating them separately in EFS 40, GFS 40 and DFS 40 at 1$0^{\circ}C$. The results obtained are as follows : 1. Freezing in the state of vitrification and thawing late mouse molulae after equilibrating them at l0$0^{\circ}C$ in EFS 40 for 30 seconds, one minute and two minutes, we obtained survival rates of 76.7%, 96.7% and 100%, respectively. 2. Freezing and thawing them after equilibrating at 1$0^{\circ}C$ in GFS 40 for 30 seconds, one minute and two minutes, we obtained survival rates of 60%, 96.7% and 10%, respectively. These results are as similar as in the case of EFS 40. 3. Freezing and thawing them after equilibrating at l$0^{\circ}C$ in DFS 40 for 30 seconds and one minute, we obtained survival rates of 62.1% and 0%, respectively. These results represent lower survival rates than those obtained with EFS 40 and GFS 40. In conclusion, even equilibrating late mouse molulae in EFS 40 and GFS 40 at 1$0^{\circ}C$ for more than one minute gives a survival rate of more than 97%, while equilibrating them in DFS 40 at 1$0^{\circ}C$ for more than one minute results in a 0% survival rate, which means that DFS 40 has a strong toxicity.

• Journal of Periodontal and Implant Science
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• 제39권sup2호
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• pp.205-212
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• 2009

Purpose: The aim of this retrospective study was to compare the survival rate of oxidized titanium implants and sandblasted large-grit acid etched implants in soft bone. Methods: 201 oxidized titanium implants were inserted in 84 patients between May 1999 and May 2004. 120 sandblasted large-grit acid etched implants were inserted in 74 patients between December 2000 and May 2004. The patients were followed-up 0${\sim}$5 years in ITI group or 0${\sim}$6 years in BRA group, respectively. The following information was collected from the patient records: age, gender, systemic disease, implant type, number, length and diameter of the implants, their location in the jaws, bone quantity, the number of failed implants, the causes of failure, and advanced surgery for bone augmentation. Results: In the oxidized titanium implants, 8 implants showed early failure, and 1 implant showed late failure, respectively. The cumulative survival rate was 95.48%. In the sandblasted large-grit acid etched implants, 1 implant showed late failure and cumulative survival rate was 99.10%. The cumulative survival rate and the survival rates in the case of the advanced procedure during the implant placement were not significantly different in both groups. Conclusions: Oxidized titanium implants and sandblasted large-grit acid etched implants can be used successfully in soft bone regardless of the surgical methods used during the implant placement. (J Korean Acad Periodontol 2009;39:205-212)