• The Korean Journal of Applied Statistics
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• v.29 no.1
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• pp.113-122
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• 2016

Longitudinal data often occur in prospective follow-up studies. Joint model for longitudinal data and failure time has been applied on several works. In this paper, we extend it to the case where longitudinal data involve informative observation time process as well as competing risks survival times. We use a likelihood approach and derive an EM algorithm to obtain maximum likelihood estimate of parameters. A suggested joint model allows us to make inferences for three components: longitudinal outcome, observation time process and competing risk failure time. In addition, we can test the association among these components. In this paper, liver cirrhosis patients' data is analyzed. The relationship between prothrombin times measured at irregular visiting times and drop outs is investigated with a joint model.

• Journal of Chest Surgery
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• v.35 no.10
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• pp.705-711
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• 2002

The advantages of mitral valve reconstruction have been well established and so mitral valve reconstruction is now considered as the procedure of choice to correct mitral valve disease. This is the report of intermediate-term results of 38 cases that performed mitral valve reconstruction for valve insufficiency(the total number of mitral valve reconstruction were 49 cases, but 11 cases that performed mitral valve replacement due to incomplete reconstruction were excluded). Material and Method : From March 1991 to March 2001, 38 patients underwent mitral valve repair due to mitral valve regurgitation with or without stenosis. Mean age was 47.6$\pm$14.7 years(range 15 to 70 years) : 11 were men and 27 were women. The causes of mitral valve regurgitation were degenerative in 14, rheumatic in 21, infective in 2 and the other was congenital. Result : According to the Carpentier's pathologic classification of mitral valve regurgitation, 3 were type 1 , 16 were type II and 19 were type III. Surgical procedures were annuloplasty 15, commissurotomy 19, leaflet resection and annular plication 9, chordae shortening 11, chordae transfer 5, new chordae formation 2, papillary muscle splitting 2 and vegetectomy 2. These procedures were combined in most patients. There were 2 early death and the causes of death were respiratory failure, renal failure and sepsis. There was no late death. Valve replacement was done in 6 patients after repair due to valve insufficiency or stenosis 3 weeks, 1, 3, 51, 69, 84months later respectively. These patients have been followed up from 1 to 116 months(mean 43.0 months). The mean functional class(NYHA) was 2.36 pre-operatively and improved to 1.70. Conclusion : In most cases of mitral valve regurgitation, mitral valve reconstruction when technically feasible is effective operation that can achieve stable functional results and low surgical and late mortality.

• Korean Journal of Construction Engineering and Management
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• v.20 no.3
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• pp.113-121
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• 2019

The death rate of industrial accidents per 10,000 people in Korea is two to three times higher than that of major countries. Falling accidents at the construction site happened to have caused the most deaths. Analysis of existing research and measures by national institutions showed that the industrial accident management concentrated on falling accidents was insufficient and the seasonal safety management measures were not enough. There is thus the need for research that provides detailed and enough information on falling accidents. This study, therefore, aims to overcome the limitations of existing research and safety management accident response using a methodology that provides the necessary information for the prevention of fall accidents by deriving seasonal crash characteristics of the construction site. In order to provide enough information, 387 cases of seasonal construction site falling were collected, which describes the causal relationship of accidents. Text mining using principal component analysis and cluster analysis was carried out. The analysis showed that: In the spring, snowfall and unreasonable operation of equipment including lifts were the major cause. In summer, most accidents were caused by form, insufficient safety inspection, and installation work. In autumn, weather factors such as wind and typhoon were the cause. In winter, material transportation, exterior wall work, and ignore safety precautions were the cause of the crash.

• Journal of Chest Surgery
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• v.33 no.7
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• pp.547-551
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• 2000

Background; The purpose of this study was to analyze the early and midterm results of Cabrol technique to assist in making future decisions on a more adequate technique for repairing aortic root diseases. Material and Method; From August 1993 to July 1999, we performed Cabrol technique in 18 patients ; 12 annuloaortic ectasia, 6 Stanford type A aortic dissection. Male and female ratio was 11;7, mean age was 46.9$\pm$12.3 years and mean follow up period was 22.5$\pm$21.5 months. We analysed the factors influencing postoperative complications and early mortality. The factors were old age(>60 years), high NYHA(>III), preoporative concomitant disease, urgency of operation, concomitant procedure, long pump preoperative concomitant disease, urgency of operation, concomitant procedure, long pump time(>200 minute), and hospital stay time (>30 days). Result; Operative mortality was 11.1%, late mortality was 11.1%, and overall mortality was 22.2%. The causes of operative death were a heart failure and an arrhythmia. The causes of late death were an acute myocardial infarction and an unknown etiology. Postoperative complications were bleeding, wound infection, toxic hepatitis, acute renal failure, and cerebral infarction. The factors influencing postoperative complications were hihg MYHA Fc(>III) (p=0.044), concomitant disease (p=0.044), long pump time(>200 minute)(p=0.015), and concomitant procedure(p=0.004). There were no significant factors influencing early mortality. Conclusion; The lower postoperative bleeding rate and no complication related to tension of anastomosis after Cabrol technique warrant its consideration in patients requiring aortic root replacement, especially without feasible mobilization of coronary arteries. However, to confirm the graft thrombosis, a more detailed study including periodic angiography will be required.

• Journal of Chest Surgery
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• v.34 no.2
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• pp.148-155
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• 2001

배경: 본 연구는 1987년부터 1997년까지 원자력병원에서 수술을 시행한 500명의 식도암환자를 대상으로 하여 휴향적 방법을 통해 조기 및 장기성적, 재발양상, 예후인자 등을 보고하고자 한다. 대상 및 방법: 대상환자 중에서 발병암이 있는 경우, 인두식도 경계부위나 위식도 경계부위 암, 고식적 우회술 또는 인공식도 삽입예 그리고 시험적 개흉술이나 개복술 만을 시행한 경우는 제외 시켰다. 식도 절제는 대부분 우측 개흉술을 이용한 Ivor Lewis 술식을 사용하였고 대부분의 문합은 stapler를 사용하였다. Extended lymph node dissection은 1994년 8월부터 시행하였고 그 이전에는 standard lymph node dissection을 하였다. 96.8%에서 위를 식도 대체장기로 사용하였고 경부에서 절제 및 재건술을 시행한 경우를 제외한 모든 식도재건은 후종격동을 통해 시행하였다. 결과: 474예(94.8%)가 편평상피 세포암이었고 대부분(58.2%)은 중부식도에 위치하였다. 술후병기는 47.4%가 stage III이었고 25%가 stage IIA이었다. 392예에서 근치적 절제가 가능하였고 74예는 고식적 절제를 시행하였으며, 식도열공을 통한 식도절제술과 경부에서의 유리공장 이식술을 시행한 34예는 위분류에서 제외하였다. 술후 유병율은 38.4%이었고 수술 사망률은 5.8%로 호흡기 감염, 문합부 유출이 주요 원인이었다. 대상환자의 99.8%에서 추적은 가능하였고 수술사망 예를 포함한 전체환자의 1, 2, 5년 생존율은 각각 63.5%, 38.9%, 19.4% 이었다. Standard lymph node dissection 그룹에서의 1, 2, 5년 생존율이 60.7%, 35.9%, 16.9%이었으나 extended lymph node dissection그룹에서는 1, 2, 4년 생존율이 70.2%, 46.5%, 30.9%이었다. 근치적 절제의 경우는 1, 2, 5년 생존률이 69.4%, 43.9%, 21.9%이었고, 고식적 절제의 경우는 37.8%, 17.6%, 7.3%이었다. 수술사망을 제외한 근치적 절제술과 extended lymph node dissection을 함께 시행한 경우의 4년 생존율은 35.6%이었다. 수술후 재발은 226예에서 발견되었고 주로 국소임파절(69%; 경부, 종격동, 복부)이었으며, 전신재발은 간, 폐, 뼈, 뇌 등의 순이었다. 결론: 저자들은 적절한 술후 환자관리가 선행되어야 하지만 근치적 절제와 광범위한 임파절 절제가 장기성적의 향상에 필수적 요소이고, 진행된 식도암에 있어서는 보다 효과적인 보강적 복합치료가 연구되어야 할 것으로 생각된다.

• The Journal of the Korean life insurance medical association
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• v.25
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• pp.9-24
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• 2006

지속적으로 증가 하고 있는 악성 종양 발병률의 증가, 생존률의 향상, 조기발견의 증가 등이 암 기왕자의 보험 수요 상승을 가져오고 있으며, 보험시장에서 더 이상 암 기왕자를 도외시하기 어렵게 만들고 있다. 그러나, 현재 국내에서는 암 기왕자를 인수할 수 있는 상품과 언더라이팅 인수 기법이 부족한 실정이다. 본 논문은 이러한 상황 하에서 기존에 거절체로 인식되었던 암 기왕자의 적극적인 인수를 위해 악성종양에 대한 보험 의학적인 고찰과 사망률, 위험도에 대해 분석하고, 국내에서 암 기왕자의 보험 인수 시 문제점과 그 해결방안을 모색해 보았다. 종양은 종양세포의 성장과 확산의 정도를 나타내는 병기와 조직학적 등급에 의해 그 예후와 경과가 예측 가능하며, 이 병기를 표준화하려는 국제적 시도로 1977년 American Joint Committee on Cancer(AJCC)는 TNM system 을 제시하였다. 병기를 기초로 치료의 결정도 함께 이루어지는데, 주요 치료법을 수술, 방사선치료, 항암치료, 면역요법이 있다. 이러한 치료법들은 후기 부작용을 일으키거나 이차성 암(Secondary malignant neoplasm)의 원인이 되기도 한다. 병기에 따른 암환자의 사망률을 살펴 보면, 암은 일정시기 동안 사망률이 급격히 증가하다가 이후에 점차 사망률이 감소하고, 그 이후에는 사망률에 영향을 미치지 않는다. 이러한 사망률 변화의 특성은 암 기왕자에게 평준식 정액 할증법(Per mille flat extra)의 적용이 적절함을 보여준다. 그러나, 현재 국내에서는 악성 종양 기왕자를 위한 상품이 전무한 상태이며, 암의 병리적 병기와 치료에 관련된 정보를 얻을 수 있는 도구도 부족하고, 명확한 인수 기법이 없다. 또한, 자체의 경험통계의 부족으로 위험에 대한 부담감이 큰 것이 현실이다. 하지만, 병기에 따른 사망률의 변화에서도 알 수 있듯이 평준식 정액 할증법의 도입이나, 악성종양의 병기(Stage)별 정액 할증률을 삭감법으로 전환하는 기준을 개발한다면, 종신보험은 충분히 인수가 가능하다. 또한, CI 보험도 암에 대한 부담보를 하는 선진사의 인수 기법을 도입하거나, 암 기왕자만을 위한 CI 상품을 개발하는 등 새로운 인수 기법을 모색한다면, 암기왕자 인수의 폭은 넓어질 것이다. 이와 같은 노력과 함께, 언더라이팅의 정보 획득을 위한 암 기왕자만의 고지서를 개발하고, 전문 언더라이터의 양성을 위한 노력을 게을리 하지 않는다면, 암기왕자를 적극적으로 인수할 수 있을 것이다. 앞으로 국내 보험사가 위와 같은 노력을 지속적으로 해 나가고, 비교적 예후와 경과가 양호한 0기와 1기 암 기왕자부터 단계적으로 종신보험의 인수를 시도한다면, 비교적 안전하게 경험치를 축적할 수 있을 것이다. 뿐만 아니라 국내 보험업계는 새로운 시장의 확보와 보험에 대한 대외 이미지 개선이라는 효과도 함께 얻게 될 것이다.

• Neonatal Medicine
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• v.18 no.2
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• pp.221-227
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• 2011

Purpose: The objectives were to identify the characteristics of neonates with hydrops fetalis, and to identify the risk factors associated with mortality. Methods: A retrospective review of AMC (Asan Medical Center) dataset was performed from January 1990 to June 2009. The characteristics of 71 patients with hydrops fetalis were investigated and they were divided into two groups: the survived group and the expired group. Various perinatal and neonatal factors in two groups were compared to find out risk factors associated with mortality based on univariate analysis, followed by multiple regression analyses (SPSS version 18.0). Results: Of those 71 neonates (average gestational age: 33 weeks, birth weight: 2.6 kg), 38 survived, 33 died, resulting in overall mortality rate of 46.5%. The most common etiology was idiopathic followed by chylothorax, cardiac anomalies, twin-to-twin transfusion, meconium peritonitis, cardiac arrythmias, and congenital infections. Factors that were associated independently with mortality in logistic regression analyses were low 5-minutes Apgar score, hyaline membrane disease and delayed in achieving 50th percentile ideal body weight for appropriate gestational age by 10 days. Conclusion: In this study, 5-minutes Apgar score, hyaline membrane disease and delayed in achieving 50th percentile ideal body weight for appropriate gestational age by 10 days were significant risk factors associated with mortality in hydrops fetalis. Therefore, the risk of death among neonates with hydrops fetalis depends on the illness immediately after birth and severity of hydrops fetalis. Informations from this study may prove useful in prediction of prognosis to neonates with hydrops fetalis.

• Journal of Korean Society of Transportation
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• v.26 no.2
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• pp.167-176
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• 2008

Although a rate of car accident death is on the decrease, internal rate of median encroachment accident is still high. In order to reduce the median encroachment accident, government use median barriers but there are no exact criteria of them. Particularly, current impulse measurement method has adopted the uniformly operating speed and encroachment angle. At reality, however, there are various conditions depends on driver's characters. In that reason, this study calculates reasonable impulse quantity through encroachment angle and operating speed. It will be necessary to prevent overuse treasury and car accidents.

• Korean Journal of Head & Neck Oncology
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• v.15 no.2
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• pp.232-234
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• 1999

Distant metastases of head and neck cancer have become an increasingly common cause of death as local and regional control has improved. The most frequent metastatic sites of head and neck cancer are the lung, liver, bone and kidney; but metastases to the gastrointestinal tract, brain and heart have also been reported. We report a recent case of a 37-year-old male patient with squamous cell carcinoma of the tonsil who had undergone composite operation with left radical neck dissection and postoperative radiotherapy. The patient presented three years later, cachexic and complaining of severe deep seated headache. Radiologic evaluation revealed a cystic mass with peripheral enhancement in left temporal lobe that was proven to be metastatic cancer by burrhole exploration. However, in spite of various modalities, the patient expired.

• Korea journal of population studies
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• v.35 no.1
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• pp.131-149
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• 2012

This study examined the effect of parental socioeconomic position on the association between birth outcomes and infant mortality in early and late 2000's. Linked Birth and Infant Death data sets from 2001 to 2003 (T1) and from 2006 to 2008 (T2), provided by the Korea National Statistical Office, were used for analysis. Birth outcomes were categorized into four groups: normal term, small-for-gestational age (SGA), large-for-gestational age (LGA) and intrauterine growth retardation (IUGR). Infant death was defined as the death of a live-born child under one year of age; indicators of parental socioeconomic position were limited to parental education and occupation. The results showed that T2 infant mortality hazard ratios of SGA and IUGR have increased compared to T1. Particularly, preterm and low birth weight babies with shorter gestational age and lighter birth weight than T1 have elevated in T2, possibly indicating that population quality might be continuously aggravated. Moreover, the effect of maternal age on infant mortality has disappeared, rather that of parents' socioeconomic position has increased during the periods, which entailed growing disparities in infant mortality by their social class. Further studies should be therefore done to estimate the effect of parental socioeconomic position on the relationship between birth outcomes and infant mortality in the near future.