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너비 및 높이 변화에 따른 일반형 자연환기 벤틸레이터 배기유량 산정
하현철,김태형 한국산업위생학회 2003 한국산업보건학회지 Vol.13 No.1
As a strategy of natural ventilation, the standard type of general gravity ventilator can be installed on the roof of an industrial building. The modified shape of ventilator with different width and/or height ratio was often used for improving ventilation efficiency and assuring structural safety concem. Although the ventilation rates could ve affected by different ventilator width and/ of height, the design data of appropriate ventilation rate have not been established yet. In this study, the ventilation rates of both standard and modified gravity ventilator were thus estimated for the purpose ofcomparison of ventilation dfficiencies. For the standard gravity ventilator, the factorial combinations of 4 parameters( 3 wind directions, 6 wind speeds, 5temperature differences and 3 ventilator neck widths) which consist of 270 cases. were simulated. Additionally, for the modified gravity ventilator, the factorial combinations of 5 parameters (3 wimd directions, 5wind speeds, 9 temperature differences, 3 ventilaor neck widths and 2 modified ventilator heights) which result in 270 caces, were simulated. A commercially available CFD code, FLUENT(Ver. 6. 0) package, was used to estimate the ventilation rates numerically. it was found from the thorough analyses that the ventilation performance were enhanced as ① wind direction is close to the latitudinal direction of industrial building, ② wind speed increases. ③ the temperature difference between the exterior and interior of a building increases and ④ ventilator neck is wider. The flow rate of low height ventilator is lower than that of standard height ventilator while the flow rate of taller ventilator was not increased proportionally. Therefore, standard ventilator is more suitable than modified ventilator for effective and safe ventilation.
하현철 대한흉부심장혈관외과학회 1995 Journal of Chest Surgery (J Chest Surg) Vol.28 No.2
From January, 1983, to August, 1993, 23 cases of pericardiectomy for chronic constrictive pericarditis were carried out. The 15 male and 8 female patients ranged in age from 7 to 68 years[mean 39.1 years . All patients underwent pericardiectomy through a median sternotomy. Postoperative complications were low cardiac output[2 patients , wound infection[2 patients , pneumonia[2 patients , and unilateral phrenic nerve palsy[2 patients . One patient died of low cardiac output 1 day after pericardiectomy due to the associated transposition of great artery and hypoplastic right lung. Clinical and pathological findings showed that the cause of constrictive pericarditis was tuberculous in 8 cases[34.8% , idiopathic in 12 cases[52.2% and pyogenic in 3 cases[13.0% . Central venous pressure fell below 10cmH2O by immediate in 6 cases, fell below 10cmH2O by 24hrs in 5 cases and continued above 10cmH2O after 24hrs in 12 cases. Preoperative NYHA functional class of patients showed class I-1, classII-4, class III-14, and class IV-3. Postoperativly NYHA functional class was improved to class I-15, classII-6, class III-1.
하현철 대한흉부심장혈관외과학회 1994 Journal of Chest Surgery (J Chest Surg) Vol.27 No.8
Congenital coronary arteriovenous fistula is relatively rare congenital heart disease which has formation of fistula between coronary artery and cardiac ventricle, atrium, or pulmonary artery, but that can be repaired with simple surgical procedure. We experienced three cases of congenital coronary arteriovenous fistula, which were repaired surgically under cardiopulmonary bypass, so we report these cases with review of the literatures.
Lakatos의 증명과 반박의 원리를 활용한 주제 탐구형 교수․학습 상황 분석
하현철,윤종국 한국교원대학교 교육연구원 2011 敎員敎育 Vol.27 No.4
The purpose of this study is to plan actual teaching․learning by selecting 'finding days', 'finding the Fermat point', and 'finding the center of gravity in quadrangle' as the teaching·learning materials that students are expected to meet various trials and errors based on literature review, finally, it was to seek the applicable possibility to the actual mathematics education situation in high schools by applying to and observing actual teaching and analyzing it based on Hwang(2001)'s classification of mathematical thinking. The researcher has suggested the reasoning, proved it, found counterexample against it, and improved the reasoning in order to solve each question in the situation of teaching·learning to use by Lakatos' proof and refutation. Therefore, students' various thinking skills about mathematics have been revealed in the improving process about reasoning. In conclusion, this study have made students experience fundamental aspect to develop the process of mathematical knowledge by teaching·learning to use the Lakatos' proof and refutation, furthermore, this has been reconfirmed as the valuable one in the field of education because a variety of thinking in mathematics have been found in this process. Furthermore, 'finding days', 'finding the Fermat point', and 'finding the center of gravity in quadrangle' used as the teaching·learning materials in this study can be valuable as the teaching·learning ones using the Lakatos' proof and refutation for high school students. Therefore, if example of teaching·learning situation presented in this study is modified, redeemed, and used to meet the goal, the meaningful activity for teaching·learning can be achieved. 본 연구는 문헌탐구에 기초하여 학생들의 다양한 시행착오가 예상되는 교수․학습 소재로서 ‘요일 찾기’, ‘Fermat의 점 찾기’ 그리고 ‘사각형의 무게중심 찾기’를 선정하여 Lakatos의 증명과 반박의 원리에 따른 교수․학습에 적용한 후, 황혜정(2001)의 수학적 사고의 분류에 따라 분석해봄으로써 실제 고등학교 수학교육 현장으로 적용가능성을 모색해보고자 한다. 의도적(purposive) 표본선정 방법으로 4명의 연구 대상자를 선정하여 정성적 사례연구를 실시한 결과 다음과 같은 결론을 얻었다. Lakatos의 증명과 반박의 원리를 활용한 교수․학습은 학생들이 다양한 추측을 제기하고 추측에 대한 반례를 찾으며 반례를 분석하여 이전보다 세련되고 확장된 추측의 개선을 경험함으로써 수학적 지식이 발전하는 과정의 본질적 측면을 학생들이 체험할 수 있고 그러한 과정에서 다양한 수학적 사고가 발현된다는 측면에서 교육적 가치가 있다는 점을 확인할 수 있었다.
Docetaxel에 의한 비소세포폐암세포주 NCI-H1703의 세포사멸 유도기전
하현철,김영대,송승환,박진수,김종원 대한흉부외과학회 2006 Journal of Chest Surgery (J Chest Surg) Vol.39 No.9
Taxene계 화학요법제로서 항암치료에 사용되고 있는 docetaxel은 폐암을 포함한 다양한 종양에서 효과적인 항암 치료제로 사용되고 있다. Docetaxel에 의한 폐암세포의 사멸 유도 기전은 정확히 알려져 있지 않으며, 기전을 연구하기 위해 docetaxel로 처리한 NCI-H1703 세포의 세포주기 및 형태적 변화를 유세포측정기, 형광현미경, western blot 분석법을 통하여 확인하였다. 그 결과 docetaxel은 의미 있게 S기를 감소시키고 G2기를 증가시킴으로써 NCI-H1703 세포의 사멸을 증가시켰다. Docetaxel에 노출되었을 때 caspase-3와 caspase-9의 활성이 증가되었다. 이들 결과를 종합해볼때, docetaxel은 H1703의 세포사멸 유도 시 caspase-3 의존성 미토콘드리아 관련 세포사멸기전으로 apoptosis를 일으키는 것으로 생각한다.