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      • KCI등재

        Transcatheter Closure of Atrial Septal Defect: Does Age Matter?

        김남균,박수진,최재영 대한심장학회 2011 Korean Circulation Journal Vol.41 No.11

        Atrial septal defect (ASD) is the most common type of common congenital heart disease (CHD) in adults. During the last decade, there has been a remarkable change in the treatment strategy of ASD, shifting the therapeutic gold standard from surgery to transcatheter closure, along with refinements and the evolution of device technology. Reports on the outcome of transcatheter ASD closure have shown an excellent efficacy as well as a low complication rate. However, the procedural details and/or outcomes of this procedure may be influenced by several factors including morphologic characteristics of the defect, co-morbid diseases, as well as individual factors including age and weight of the patient. Because the risk-benefit relationship in both the very young and the elderly subsets of the patients has not been clearly defined yet, closure of an ASD with device may be potentially subtracted from the treatment option in these patient groups. In this article, we will review the basis for device closure in small children and elderly patients with ASD and provide an overview of the frequently encountered problems.

      • KCI등재
      • KCI등재

        Predictive Value of Estimated Glomerular Filtration Rate for the Prognosis of Elderly Patients With Acute Myocardial Infarction

        김남균,박훈식,윤재용,조현준,김창연,노재형,배명환,이장훈,양동헌,조용근,채성철,손지현,장세용 대한노인병학회 2017 Annals of geriatric medicine and research Vol.21 No.1

        Background: The aim of this study was to investigate the predictive value of estimated glomerular filtration rate (eGFR) calculated with the simplified Modification of Diet in Renal Disease (MDRD) Study and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations for prognosis in elderly patients with acute myocardial infarction (AMI). Methods: This study included 1,372 patients (mean age, 64.2±11.8 years; men, 67.9%) entered in the Kyungpook National University Hospital Acute Myocardial Infarction Registry from November 2005 to February 2010. We analyzed 1-year major adverse cardiac events (MACE) according to the eGFR calculated with the simplified MDRD Study and CKD-EPI equations. Results: The mean eGFR values calculated with the MDRD Study and CKD-EPI equations were 81.3±44.4 and 78.5±27.1 mL/(min/1.73 m2), respectively. In receiver operating characteristic curve analysis for prediction of 1-year MACE, the area under the curve based on the CKD-EPI equation was greater than that using the MDRD Study equation (CKD-EPI equation vs. MDRD Study equation: 0.691 vs. 0.674, p=0.041). Multivariate analysis using a Cox proportional hazards model revealed that the eGFR calculated with the CKD-EPI equation was an independent predictor of the occurrence of MACE within 1 year after AMI. However, eGFR calculated with the MDRD Study equation did not have predictive value. Furthermore, the eGFR calculated with the CKD-EPI equation had incremental prognostic value for established risk factors (chi-square=5.78, p=0.016). Conclusion: The eGFR calculated using the CKD-EPI equation was an independent predictor of 1-year MACE in elderly patients with AMI.

      • S-234 : Clinical SYNTAX predicting clinical outcome in patients with acute myocardial infarction

        김남균,김창연,김재희,장세용,박선희,배명환,이장훈,양동헌,박헌식,조용근,채성철 대한내과학회 2013 대한내과학회 추계학술대회 Vol.2013 No.1

        Background: Although original SYNTAX (Synergy between Percutaneous Coronary Intervention (PCI) with TAXUS and Cardiac Surgery) score (SS) excluded the patients undergoing primary PCI, several studies reported that SS could provide prognostic information in those subjects. The aim of this study is to assess whether clinical SS (CSS) would improve the ability to predict major adverse cardiac events (MACEs) compared with original SS in patients undergoing primary PCI. Methods: Between November 2005 and November 2011, 691 patients (515 men; mean age=61.9±12.0 year-old) underwent primary PCI with a diagnosis of first ST-segment elevation MI (STEMI) were analyzed in this study. CSS was calculated by multiplying the SS to an ACEF score (age/left ventricular ejection fraction + 1 if serum creatinine >2 mg/dL). Patients were categorized into 3 groups according to tertiles of CSS; CSSLOW (<14.5, n=230), CSSMID (14.5-26.7, n=231), and CSSHIGH (≥26.8, n=230). The 12-month MACEs were defined as death, non-fatal MI, and revascularizations. Results: During the follow-up, the 12-month MACEs were 5.2% (SSLOW; ≤22), 10.3% (SSMID; 23-32), and 18.9% (SSHIGH; ≥33), respectively (p<0.001), whereas 3.5% (CSSLOW), 5.6% (CSSMID), and 12.2% (CSSHIGH), respectively (p<0.001). CSS (39.5±29.1 versus 23.1±17.2, p<0.001) as well as SS (21.9±9.8 versus 17.1±8.6, p<0.001) was significantly higher in patients with 12-month MACEs. In Cox proportional hazards model, CSS (hazards ratio [HR] 1.03, 95% confidence interval [CI] 1.02-1.04; p <0.001) as well as SS (HR 1.04, 95% CI 1.01-1.07; p=0.016) was an independent predictor of 12-month MACEs after adjusting for conventional clinical risk factors. In receiver operating characteristics curves, area under the curve (AUC) of CSS was significantly higher compared with those of SS (0.694 versus 0.642, p=0.02). CSS significantly improved net reclassification (0.317, p=0.03) and the integrated discrimination (0.03, p=0.02) of patients compared to SS. Conclusions: In patients underwent primary PCI, we should consider clinical characteristics such as CSS as well as angiographic findings such as SS in decision-making for STEMI.

      • KCI등재

        유한요소법에 의한 대전력 IGBT 모듈의 열.응력해석

        김남균,최영택,김상철,박종문,김은동 한국마이크로전자및패키징학회 1999 마이크로전자 및 패키징학회지 Vol.6 No.4

        유한요소법을 이용한 IGBT 3상 풀브릿지 모듈의 열.응력 해석을 수행하였다. 패키지 재료에 의한 영향을 살피고자 AIN과 $A1_2O_3$절연기판을 사용한 경우를 비교하였으며, 적층구조의 규격을 변화시켜 열해석 및 열응력 해석결과를 비교하였다. 열해석 경계조건 설정에 따른 차이를 비교하기 위하여 등가열전달계수 경계조건(FHTCC)과 일정온도 경계조건(CTC)으로 나누어 해석하였다. 절연기판 면적의 증가는 열저항 감소에 거의 기여하지 못하였으나 열응력 감소에는 상당한 효과를 보였는데, 기판면적이 3배 넓어지면 열저항 감소분은 $A1_2O_3$ 절연기판 모듈에서 8.9%정도, AIN 절연기판 모듈에선 1.5% 정도 감소하는데 그쳤으나 열응력은 최고 60%의 감소를 보였다. 또한 솔더의 두께가 증가할수록 열저항은 증가하였으나, 열응력은 감소 또는 일정하게 유지함을 확인하였다. 각 모듈에서 최대응력값은 모두 절연기판과 접촉된 상, 하부 Cu pad에서 발생하였으며 모듈 패키지 가장자리 부분보다는 중앙부의 응력값이 높았다. A finite element method was employed fort thermal and stress analyses of an IGBT module of 3-phase full bridge. The effect of material parameters such as substrate material, substrate area, solder thickness on the temperature and stress distributions of the module packages has been investigated. Thermal analysis results have also been compared by setting of boundary conditions such as equivalent heat transfer coefficient or constant temperature at a base metal surface of the package. The increase of ceramic substrate area up to 3 times does little contribution to the reduction(8.9%) of thermal resistance, while contributed a lot to the reduction(60%) of thermal stress. Thicker solder resulted in higher thermal resistance but did slightly reduced thermal stresses. It is revealed by the stress analysis that maximum stress was induced at the region of copper pads which are bonded with ceramic substrate.

      • KCI등재

        계면활성제 첨가에 따른 함수율에 관한 실험적 연구

        김남균,이동호 한국화재소방학회 2015 한국화재소방학회논문지 Vol.29 No.2

        '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

        The fire accident is a representative type of disaster that can largely impact on business. Therefore, precautionary measuresand rapid initial response is very important when a disaster occurs. The storage of porous combustibles is inevitablein coal yard, plywood processing industry, and others that are currently operating. Initial fire fighting of fire and identifyingthe ignition point in such a porous combustible storage space are so difficult that if the initial response is failed, beingled to deep-seated fire, surface fire is likely to result in secondary damage. In addition, deep-seated fire can cause personalinjuries and property damage due to a large amount of toxic gases and reignition. Therefore damage reduction measuresis required around the storage space to handle a porous flammable. Improving the penetration performance of theconcentration of the surfactant is carried out as underlying study, which is about an deep-seated fire extinguishing efficiencyaugmentation when using wetting agents. The porous materials used in the experiments is radiata pine wood flour,which occupies more than 75% of the domestic wood market. Fire fighting water is selected as Butyl Di Glycol (BDG),which is being used for infiltration extinguishing agent, and the experiment was carried out by producing a standard solution. The experiment was carried out on the basis of the Deep-Seated Fire Test of NFPA 18. The amount of watering,porous material to the internal amount of penetration, and runoff measurement out of the porous material was conducted. According to experimental results, as the surface tension is reduced, the surfactant concentration macroscopic penetrationrate decreases, but infiltration to a porous material is shown to have growth characteristics. 화재사고는 그 충격과 영향이 업무중단 및 기업의 존폐를 좌우 할 수 있는 대표적인 재난 유형이다. 따라서 사전 예방, 대비는 물론 재난 발생 시 신속한 초기대응이 매우 중요하다. 현재 운용되고 있는 저탄장 및 합판 가공 산업 분야등에서는 다공성 가연물의 저장이 불가피하다. 다공성 가연물 저장 공간의 화재는 그 특성상 발화시점의 파악 및 초기진압이 어려우며, 초동 대처에 실패할 경우 표면화재에서 심부화재로 이어져 2차 화재피해가 발생할 가능성이 높다. 또한 심부화재는 다량의 독성가스발생과 재발화로 인해 인적 · 물적 피해를 야기할 수 있으므로 다공성 가연물을 취급하는저장공간을 중심으로 피해경감 대책이 요구된다. 본 연구는 침윤소화약제 사용 시 다공성 물질의 심부화재 소화 효율 증대에 관한 기초 연구로써, 계면활성제의 농도에 따른 침투성능의 향상에 관한 연구를 수행하였다. 실험에 사용된 다공성물질은 국내 사용 목재의 75%를 점유하고 있는 뉴질랜드산 소나무의 원목 목분을 사용하였다. 소화용수는 침윤소화약제에 사용되고 있는 Butyl Di Glycol (BDG)을 선택하여 농도에 따른 표면장력별 표준시료를 제작하여 실험을 수행하였다. 실험은 NFPA 18의 Deep-Seated Fire Test를 기초로 수행하였으며, 살수량과 다공성 물질 내부로의 침투량, 다공성물질 외부로의 배출량 측정 실험을 실시하였다. 실험결과 계면활성제 농도에 따른 표면장력이 감소함에 따라 거시적 침투속도는 감소하나 다공성 물질 내부로의 침투량은 증대되는 특성을 확인하였다.

      • KCI등재
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