• Korean Journal of Ecology and Environment
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• v.46 no.3
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• pp.395-408
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• 2013

Environmental condition can induce changes in early life-history traits in order to maximise the ecological fitness. Here I investigated how temperature change and variation in human aquatic activity/behaviour affect early life-history consequences in fish using a dynamic-state-dependent model. In this study, I developed a general fish's life-history model including three life-history states depend-ing on foraging activity, such as body mass, mass of reproductive tissue (i.e., gonadal development) and accumulated stress (i.e., cellular or physiological damage). I assumed the level of foraging activity maximises reproductive success-ultimately, fitness. The model predicts that growth rate, development of reproductive tissues and damage accumulation are greater in higher temperature whereas higher human aquatic activity rapidly reduced the growth rate and development of reproductive tissue and increased damage accumulation. While higher foraging activity in higher temperature is less affected by human aquatic activity, the foraging activity in lower temperature rapidly declined with human aquatic activity. Moreover, lower survival rate in higher temperature or human aquatic activity was independent on mortality rate due to human aquatic activity or mortality rate when foraging activity, respectively. However, the survival rate in lower temperature or human aquatic activity was dependent on these mortality rates. My findings suggest that including of early life-history traits in relation to climate-change and human aquatic activity on the analysis may improve conservation plan and health assessment in aquatic ecosystem.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.271-275
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• 2009

본 연구에서는 상수관로의 잔존수명을 통계적 기법 중 하나인 비례위험모형(PHM)에 적용하여 평가하였다. 비례위험모형을 구축하기 위한 개별관로의 생존시간은 관로의 파손율이 한계파손율에 도달하는 시간으로 정의하였다. 즉, Park and Loganathan(2002)에서 제시한 GPBM을 적용하여 시간에 따른 개별관로의 파손율을 추정하고 추정된 파손율과 한계파손율의 상등관계를 통해 생존시간을 산정하였다. 또한, 본 연구대상관로에 대한 GPBM을 구축함에 있어, 매설시점에서 누적파손횟수를 0으로 한 파손기록을 입력자료에 추가하는 방법과 가중계수(WF)의 범위를 수정함으로써 기존의 GPBM을 보완하였다. 이로써 파손사건이 최소 1회 이상 기록된 강관 및 주철관에 대한 비례위험모형을 구축하였다. 이와 같이 수정된 방법론은 관로 파손사건 등의 자료의 축적이 미비한 국내 여건에서 비례위험모형 및 GPBM과 같은 통계적 모형을 구축할 때 유용할 것으로 사료된다. 본 연구대상관로의 비례위험모형에 포함된 유의한 공변수는 관종과 관경 그리고 길이이며 관종은 비례성 가정을 위배하여 시간종속형 변수로 모형화되었다. 최종 채택된 PHM모형을 통해 생존함수를 추정하였으며 추정된 생존함수를 이용하여 개별관로의 잔존수명 및 경제적 수명 그리고 각 수명에 대한 95% 신뢰구간을 산정하였다. 또한 개별관로의 경제적 수명에 영향을 미치는 공변수의 위험비율도 분석하였다. 분석결과 강관의 평균 경제적 수명은 약 25.1년이고 주철관은 약 21년으로 산정되었다. 또한 관종에 따른 경제적 수명에 도달할 상대적인 위험률은 전반적으로 주철관이 높으나 20년 이상 매설된 관로에서는 강관의 위험률이 높을 것으로 분석되었다. 관경과 길이는 크기에 비례하여 상대적 위험률도 증가하였다.

• Journal of Periodontal and Implant Science
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• v.35 no.4
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• pp.1039-1052
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• 2005

IMZ는 "intramobile cylinder implant system" (IMZ)로 독일에서 가장 오래되고 많이 사용되어진 임플란트 중 하나이다. 이 임플란트에 관한 장기적 성공률과 생존률에 대한 연구는 대개 80% 이상을 보고하고 있다. 그러나, 연세대학교 치과병원 치주과에서 식립된 83개의 임플란트에서는 이전의 연구와는 다른 결과를 나타내었다. 1. IMZ 임플란트의 생존률은 67.5% 였다. 2. 변연 치조골 소실에 대한 성공 기준을 적용한 결과 성공률은 49.4%로 나타났다. 3. 발거된 총 27개의 임플란트 중에서 임플란트 주위 골소실을 가지는 경우는 17개, 내부구조 파절은 4개, 식립체 파절은 5개로 보고되었다. 4. 10년 이상 생존된 임플란트에서 변연골 소실의 평균치는 2.82mm였다. IMZ 임플란트는 장기적으로 높은 실패율을 보고하였다. 이는 cylindrical design, titanium plasma flame spray coating, prosthodontic complication 등의 요소에 기인한 것으로 사료된다. 임플란트는 그 형태, 표면 처리 등 여러 가지 요인들에 의해 실패가 나타날 수 있으며 본 연구를 통해 임플란트의 개발 및 선택에 바탕이 될 수 있을 것으로 생각된다.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.280-292
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• 2016

Purpose: The purpose of this study was to compare the long-term survival rate and peri-implant marginal bone loss related to multiple risk factors including the clinician's experience. Materials and Methods: Four hundred twenty implants in 146 patients, who had involved a supportive periodontal therapy program every 3 to 6 months and had follow up data for at least 5 years, were selected as the study group. Peri-implant marginal bone loss, data of demographic, implant and surgical characteristics were collected from peri-apical radiographs and chart review. Implant survival was regarded as the remaining with radiographic marginal bone level in excess of 50% of the fixture length for any reason. Results: The cumulative survival rate after 5 years of loading was 94.9%. In binary logistic regression analysis, smoking status (P = 0.033) and presence of spontaneous cover screw exposure (P < 0.001) were significantly related to 5-year survival of implants. In stepwise multiple regression analysis, smoking status (P < 0.001), type of abutment connection (P < 0.001) and implant surface (P = 0.033) were significantly related to peri-implant marginal bone level. And the year of resident was not statistically related to 5-year implant survival in simple logistic regression analysis (P = 0.171). Conclusion: Smoking status, spontaneous cover screw exposure, type of abutment connection and implant surface might influence the implant success. There was no significant correlation between the year of resident and implant failure.

• Journal of Yeungnam Medical Science
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• v.22 no.1
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• pp.72-80
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• 2005

Background: Nasopharyngeal cancer is a rare disease with a relatively poor prognosis because it tends to be diagnosed at an advanced stage. The aim of this study was to establish the clinical characteristics of nasopharyngeal cancer. Materials and Methods: The medical records of 54 patients with nasopharyngeal cancer from January 1993 to December 2002 were reviewed retrospectively. Forty one cases were male (75.9%) and thirteen were female (24.1%). The average age was of 46.9 (range 16 to 78 years) years. The majority of patients (79.6%) were diagnosed in the advanced stage. The most common complaints were a neck mass (55.5%) and the WHO type III (53.7%) was the most frequent histological type. Results: The cumulative survival rate for a 5-year period was 46.5% and the T stage, N stage, pathologic type, and clinical stage were not significantly related to the survival rate. Sixteen of 54 (31.5%) cases presented with a distant metastasis of the bone, lung, brain, spine, and liver, and six cases (11.1%) presented with a locoregional recurrence. Conclusion: TNM staging is not appropriate for predicting survival rate of nasopharyngeal carcinoma patients. Therefore, a newer staging system, which includes new factors, is needed to predict the prognosis.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.1
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• pp.59-68
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• 2010

Recently, dental implants extensively inserted on edentulous area show highly clinical success rate. However, clinicians cannot exclude the possibility of failure and it often unexpectively occures. Many possible factors associated with failure of dental implants have been reported but controversy exists over the extent to them. In this study, we collected 212 patients who had been inserted 358 dental implants on mandibular premolar and molar area from 2005 to 2006. The survival rate of fixtures was recorded according to age of patients, implantation site, implant system, diameter and length of fixtures. Multi-variable analysis using SPSS chi-square test was operated to verify relation of each factors and survival rates. Accumulative survival rate was 98.3% for 3 years. Only diameter of fixtures was related to the implant survival rate. This may be thought that wider fixtures had been chosen to rescue implants or used in sites of poor bone quality. Further continuous study will be needed for direct guidance associated with survival rate of implants.

• Journal of Aquaculture
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• v.17 no.1
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• pp.39-45
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• 2004

Three experiments were conducted to determine utilization of Song-Gang(equation omitted) stone as the dietary additive for growth and immune stimulant in juvenile olive flounder. In the feeding trial, four diets were formulated to contain 0, 0.5, 1.0 and 2.0% Song-Gang(equation omitted) stone per kg diet (SGS$_{0}$ , SGS$_{0.5}$, SGS$_{1.0}$ , SGS$_{2.0}$ ). Fish averaging 5.0$\pm$0.04 g (mean$\pm$SD) were fed one of four experimental diets in triplicate groups for 8 weeks. There were no significant differences in weight gain, feed efficiency, protein efficiency ratio, hematosomatic index, condition factor and survival among fish fed all the diets. In chanlenge test, fish were infected by intraperitoneal injection of 0.1 $m\ell$ bacterial suspension with Edwardsielia tarda per fish after the feeding trial. Fish fed SGS$_{0.5}$ diet have a significantly higher cumulative survival rate than did fish fed the other diets (P<0.05). In the anti-mold test, Asprrgiilus niger, Penicillium pinophiltfm, Chaeromium globosum were inoculated with Song-Gang(equation omitted) stone using ASTM G-21 method. The amount of Α. niger, Ρ. pinuphiium. C. globosum didn't increase in Song-Gang(equation omitted) stone for 4 weeks for the test period. Therefore, these results indicate that 0.5% Song-Gang(equation omitted) stone per kg diet could increase immune resistance in juvenile olive flounder and Song-Gang(equation omitted) stone could be used as the anti-mold additive in fish feed.

• Journal of Technology Innovation
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• v.26 no.4
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• pp.98-121
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• 2018

This article analyzes the survival of Korean software firms from 1995 to 2015 by Cox regression model and product-limit method. The results show that survival rates are different for each sector: IT service, package software, game software and internet service. In addition, firm growth and investment in research and development positively affect software firm's survival, while slack resources negatively affect the software firm's survival. The implication of this study is that characteristics of the software industry and technologies should be taken into consideration in survival strategy of software firms and government policy. Previous research on survival analysis has been mainly conducted in the manufacturing industry or at the special circumstance such as the foreign exchange crisis of Korea in the late 1990s. The contribution of this study is that expanding the survival analysis to software firms in Korea which are becoming more important recently.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.2
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• pp.153-162
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• 2013

This study compared the marginal bone loss around dental implants that were placed in the canine areas of the mandibles and finded the survival rate of the implants, marginal bone loss around implants and prosthetic complications in 20 patients treated with overdentures retained with Locator attachments. Implants placed in this study showed a 95% survival rate and the average marginal bone loss was 1.21 mm($SD{\pm}0.60mm$) in 94.3 weeks of functional loading. Implant-retained overdentures had various prosthetic complications such as male change, metal cap loosening, Locator attachment loosening, denture teeth change, relining and denture fracture. Implant-retained overdentures using two implants and Locator attachments in the edentulous mandibles is considered as a stable way for long terms because of minimal invasive operation, simple prosthetic process and easy repair.

• Journal of Chest Surgery
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• v.30 no.12
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• pp.1175-1183
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• 1997

Background. Infective endocarditis s an uncommon but serious disease in children. Optimal treatment strategy, especially surgical indications, continues to evolve. Method. In this report, we retrospectively reviewed 19 patients who underwent operations in Seoul National University Children's Hospital for infective endocarditis between September 1986 and February 1996. There were 8 male and 11 female patients(mean age 70.6 months) and their main symptoms were fever and dyspnea. Preoperative echocardiography detected vegetation in 14 cases out of 19. Congenital anomalies were in 15 cases and acquired forms were in 4 cases. Causative organisms were identified in 12 cases and Gram-positive cocci were in 7 cases. Adequate preoperative antibiotic management was done. Result. With cardiopulmonary bypass in all cases, surgical corrections including vegetation removal were performed. 4 patients died after operations(21.1%). All the mortality cases were having underlying complex cardiac anomalies. There were no late deaths. Act arial survival rate was 79.0% at 1 year and 79.0% at 5 year and reoperationfree survival rate was 73.7% at 1 year and 73.7% at 5 year. Collclusion. Despite advances in antibiotic therapy, early surgical treatment is imperative in a significant subset, and concurrent intracardiac repair should be appropriate.