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비행데이터 이미지 기반 Deep Learning을 통한 항공기 피로수명 예측
전병철(Byungchul Jeon),백세일(Seil Baek),김신곤(Sinkon Kim),이홍철(Hongchul Lee) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.5
항공기는 설계/개발단계에서 주요 피로취약부위에 대해 예측 운영환경을 반영한 구조해석, 피로해석을 통해 안전성을 확보한다. 실제 운영환경은 설계와 다르게 운영되므로 군용 항공기는 실제 운영 상태의 비행데이터를 반영하여 피로수명 해석을 수행하고 있다. 일부 항공기는 비행데이터에서 직접 하중/응력 스펙트럼을 생성하고 피로수명 해석을 수행함으로써 장시간의 복잡한 계산 시스템을 필요로 한다. 본 연구에서는 항공기 비행 파라미터에 대한 이미지화 과정 및 Deep Learning 기계학습 적용을 통해 효과적이고 효율적인 피로수명 예측 방안을 제시하고자 한다. 비행 파라미터에 대한 이미지화 과정은 다차원의 대량 축적된 비행데이터에 대한 Deep Learning 적용 적합성 향상에 기여하였으며, 이러한 기계학습 과정을 통해 정확도가 유지된 상태에서 수명예측 시간 단축이 가능함을 확인하였다. In the aircraft design/development stage, flight safety is confirmed through structural analysis and fatigue analysis reflecting the predicted operating environment for fatigue critical locations. Since the actual environment is operated differently from the design, the military aircraft is performing fatigue analysis by reflecting flight data of actual operating conditions. Some aircraft require time consuming and complex calculation system by generating load/stress spectra directly from flight data and performing fatigue life analysis. In this study, we propose an effective and efficient fatigue life prediction method through the application of deep learning by imaging process for aircraft flight parameters. The process of imaging flight parameters contributed to the improvement of the suitability of deep learning application to multi-dimensional mass accumulated flight data, and it was confirmed that the fatigue life prediction can be shortened while maintaining accuracy through this deep learning process.
전력구트라프간 접수냉방식에서의 지중송전케이블에 대한 열해석
박만흥(Man-Heung Park) 한국태양에너지학회 1995 한국태양에너지학회 논문집 Vol.15 No.3
원활한 전력공급을 위해 지중송전케이블에서 발생된 열을 제거하기 위한 방법으로 전력구트라프간접수냉방식이 적용된 지중송전계통에 대한 각 주요 구성요소의 열해석을 수행하였다. 열해석을 수행한 결과, 주어진 조건에서 냉동기가 채택된 냉동장치에서는 냉각수유량은 2~3l/s/pipe, 팬에 의한 풍속은 1~2m/s/fan인 경우에 지중송전계통의 원활한 전력공급을 위한 냉각계통의 최적조건으로 계산되었다. 반면에 냉각탑만을 설치한 경우에는 냉각수유량 및 풍속이 각각 2~3l/s/pipe 및 6m/s/fan이 최적조건으로 계산되었다. 그러나 냉각탑만이 설치된 경우에는 풍속이 너무 커져서 용량이 큰 팬의 설치 및 전력구내에서 작업자의 작업조건에 적합하지 않다. 따라서 본 연구의 주어진 조건하에서 지중송전계통의 냉동계통은 냉동기가 설치된 냉동장치가 바람직하다. The thermal analysis is accomplished with the route for the underground power transmission system which adopts the water pipe cooling with trough in tunnel. As a result, in case of a cooling system based on a refrigerator, the optimum condition for the flow rate of cooling water and the air velocity are calculated as the 2 ~ 3l/s/pipe and 1 ~ 2 m/s/fan, respectively. On the other hand, in case of cooling tower the optimum condition for them are calculated as the 2 ~ 3l/s/pipe and 6 m/s/fan, respectively. But the cooling system based on a cooling tower has the problem of enlarging the size of cooling fan and suppressing the labor of operator in tunnel. Therefore, to meet all the cooling conditions for a given cooling section, the cooling system based on a refrigerator is more acceptable.
배진효,박만흥,고철균,이재헌,Bae, Jin-Hyo,Park, Man Heung,Koh, Chul-Kyun,Lee, Jae-Heon 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.10
The Regulatory Guide 1.82 recommends an analysis of hydraulic performance for sump of ECCS (Emergency Core Cooing System) when LOCA(Loss of Coolant Accident) occurs in a nuclear power plant. The present study deals with 3-dimensional, unsteady, turbulent and two-phase flow simulation to examine the behavior of mixture of reactor coolant and debris near the floor of containment building in conjunction with appropriate assumptions. The dispersed solid model has been adjusted to the interfacial momentum transfer between reactor coolant and debris. According to the results, the counterclockwiserecirculation zone had been formed in the region between sump and connection aisle about 376 second after LOCA occurs. The debris thickness accumulated on a sump screen periodically increases or decreases up to 2000 second, afterwards its peak decreases.
염학기,박만흥,Yeom, Hak-Gi,Park, Man-Heung 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.2
In this paper, the unsteady state calculational model is proposed for the thermal stratification analysis in the feedwater line of the PWR plant. By defining dimensionless parameters in the two-dimensional polar coordinate system and applying SIMPLE algorithm, the temperature and flow profiles due to the thermal stratification are obtained. Base on the fact that the most significant condition occurs when the fluid temperature difference between the piping ends reaches as high as 166.deg. C, the present result shows that max. Dimensionless temperature difference of 0.6 (about l00.deg. C) obtained between hot and cold sections of pipe wall at dimensionless time 47.0.
히트 스프레더가 사용된 노트북 PC의 냉각성능에 관한 수치적 연구
노홍구,임경빈,박만흥,No, Hong-Gu,Im, Gyeong-Bin,Park, Man-Heung 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.6
Parametric study to investigate the cooling performance of a notebook PC mounted with heat spreader has been numerically performed. Two cases of air-blowing and air-exhaust at inlet were tested. The cooling effect on parameters such as, inlet velocities in the cases of air-blowing and air-exhaust, materials of heat spreader, and CPU powers were simulated for two cases. Cooling performance in the case of air-blowing was better than the case of air-exhaust.