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암반비탈면 붕괴시 예측가능한 AE의 적용성에 관한 연구
천병식,이동근,김연중,김석천 한국지반공학회 2011 한국지반공학회논문집 Vol.27 No.1
In general, many instrumentations of slope rely on theory or experience because on-site accessibility and long term instrumentation are difficult to conduct the instrumentation of slopes. Also the prediction of disaster is very difficult. Therefore experimental research was conducted about an effective method to predict collapse of slope and on-site applicability in this study. The collapse of slope was able to be predicted by applying AE sensor which we call WEAD to the failure criteria. The parameters of AE generated during the collapse of slope were secured through bending shear test. Test construction was applied to the slope with a history and a possibility of collapse. As a result, it is shown that AE parameters do not exceed the failure criterion and is found to be stable slopes. As the real symptoms of collapse did not appear, AE was found to have excellent applicability.
변요셉(Yoseph Byun),김석천(Sukchun Kim),성주현(Joohyun Seong),천병식(Byungsik Chun),정혁상(Hyuksang Jung) 한국지반환경공학회 2014 한국지반환경공학회논문집 Vol.15 No.11
사면은 건설된 후에도 집중강우나 지진, 풍화 등 외부요인으로 인해 파괴가 발생할 수 있기 때문에, 사면의 안정적 유지관리를 위해서는 사면 붕괴의 가능성을 파악하는 것이 필요하다. 특히 암반사면은 암석의 취성적인 특성으로 인해 변위 계측 등과 같은 일반적인 방법으로는 파괴발생이전에 사전징후를 감지하기 매우 어렵다. 그러나 AE 기법을 사면에 적용한다면 변위가 발생하기 전에 파괴 시 발생된 AE 신호를 분석함으로써 일반적인 계측 방법보다 초기에 상태파악이 가능할 것이다. 본 논문에서는 한국의 암반사면 중 붕괴 이력을 가지고 있는 사면에 AE 기법을 적용하여 사면붕괴 가능성을 파악하였다. 그 결과 붕괴위험이 있는 사면에 AE 기법을 적용하면 사면의 위치별 붕괴 가능성을 가능할 것으로 판단된다. A slope may fail after construction owing to external factors such as localized rainfall, earthquake, and weathering. Therefore, the grasp of failure probability for slope failures is necessary to maintain their stability. In particular, it is very difficult to detect the symptoms of rock slope failure in advance by using traditional methods, such as displacement due to the brittleness of rocks. However, Acoustic Emission (AE) techniques can predict slope failures earlier than the traditional methods. This study grasped failure probability of slope by applying AE techniques to a rock slope with a history of collapse. When applying AE techniques to a slope that has a high probability of failure, the grasp of failure probability of the specific location became possible.
급성호흡부전증 환자에서 초기 인공환기방식의 중요성 : 인공환기시 혈역학적으로 유의한 부정맥의 유발요인 분석
이영주,김원,김영득,천석천,임경수 대한응급의학회 2000 대한응급의학회지 Vol.11 No.4
Background: The purpose of this article was to identify the risk factors related to development of hemodynamically significant cardiac arrythmias in patients with mechanical ventilation. Methods and Results: Holter recording and echocardiogram were performed after 30 minutes of ventilator initiation in patients on mechanical ventilation(MV) owing to respiratory failure(RF) from various reasons. From 68 patients, hemodynamically significant cardiac arrythmias were detected in 18 patients(26.5%). Initial mean arterial pressure, maximal heart rate, and initial pH were identified as risk factors for hemodynamically significant cardiac arrythmlas. Additionally, the patients with pressure-controlled ventilation as an initial ventilatory mode developed hemodynamically significant cardiac arrythmias less frequently than the patients with other modes(15.8% vs. 40%, p=0.03). In multivariate analysis, initial mean arterial pressure(<70mmHg, odds ratio[OR]: 5.5; 95% confidence interval[CI]: 1.2 to 24.2, p=0.026), maximal heart rate(>120/min, OR: 19.7; 95% CI: 2.0 to 190.9, p=0.01), and pressure-controlled ventilation(OR: 0.13, 95% CI: 0.03 to 0.55, p=0.006) were associated with the development of hemodynamically significant cardiac arrhythmias. Conclusion: Theses findings suggest that during the early stages of mechanical ventilation with acute respiratory failure, hemodynamically significant cardiac arrhythmias are directly associated with tachycardia(>120/min), initial MAP(<70 mmHg), and, inversely, the initial use of pressure-controlled ventilation.