http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
개방 공간에서 발생하는 수소-공기 혼합 가스 폭연에 대한 실험적/해석적 연구
김양균,박병직,Kim, Yangkyun,Park, Byoung Jik 한국안전학회 2021 한국안전학회지 Vol.36 No.1
Experimental and analytical investigations are performed to explore the explosion characteristics of a hydrogen-air mixture in open atmosphere. A hydrogen-air mixture tent of total volume of 27 m<sup>3</sup>, with 40% hydrogen volume, is used to observe overpressure at a distance from the ignition source. Vapor cloud explosion analyses are performed using the TNO multi-energy model and Baker-Strehlow-Tang model. The results of these analyses are compared with experiment done from this study and references. The experimental results with and without obstacles indicate that the overpressure values measured at a distance of 4.5-21.5 m from the ignition source are about 9.4-3.6 kPa and 6.5-2 kPa, respectively. This implies that the overpressure with obstacles is approximately 1.7 times greater than that without obstacles. Analytical observation indicates that the results obtained with the Baker-Strehlow-Tang model with M<sub>f</sub> = 0.2-0.35 are in good agreement with those of most of the previous studies, including that obtained from this study. Moreover, the TNO multi-energy model with a volume of 27 m<sup>3</sup> well predicts the overpressure obtained from this study. Further studies should considered explosions in semi-confined spaces, which is more suitable for hydrogen refueling stations.
김양균,이제겸,이승원,Kim, Yangkyun,Lee, Je-Kyum,Lee, Sean Seungwon 한국터널지하공간학회 2022 한국터널지하공간학회논문집 Vol.24 No.5
As many tunnels generally have been constructed, various experiences and techniques have been accumulated for tunnel design as well as tunnel construction. Hence, there are not a few cases that, for some usual tunnel design works, it is sufficient to perform the design by only modifying or supplementing previous similar design cases unless a tunnel has a unique structure or in geological conditions. In particular, for a tunnel blast design, it is reasonable to refer to previous similar design cases because the blast design in the stage of design is a preliminary design, considering that it is general to perform additional blast design through test blasts prior to the start of tunnel excavation. Meanwhile, entering the industry 4.0 era, artificial intelligence (AI) of which availability is surging across whole industry sector is broadly utilized to tunnel and blasting. For a drill and blast tunnel, AI is mainly applied for the estimation of blast vibration and rock mass classification, etc. however, there are few cases where it is applied to blast pattern design. Thus, this study attempts to automate tunnel blast design by means of machine learning, a branch of artificial intelligence. For this, the data related to a blast design was collected from 25 tunnel design reports for learning as well as 2 additional reports for the test, and from which 4 design parameters, i.e., rock mass class, road type and cross sectional area of upper section as well as bench section as input data as well as16 design elements, i.e., blast cut type, specific charge, the number of drill holes, and spacing and burden for each blast hole group, etc. as output. Based on this design data, three machine learning models, i.e., XGBoost, ANN, SVM, were tested and XGBoost was chosen as the best model and the results show a generally similar trend to an actual design when assumed design parameters were input. It is not enough yet to perform the whole blast design using the results from this study, however, it is planned that additional studies will be carried out to make it possible to put it to practical use after collecting more sufficient blast design data and supplementing detailed machine learning processes.
역설계에 의한 비행기의 형상 구현과 수치계산에 의한 유동 가시화
김양균(Yangkyun Kim),김성초(Sungcho Kim),김정수(Jeong Soo Kim),최종욱(Jongwook Choi),박정(Jeong Park) 한국가시화정보학회 2007 한국가시화정보학회지 Vol.5 No.2
The geometry of a commercial passenger airplane is realized based on a Boeing 747-400 model through the photographic scanning and reverse engineering. The each element consisting of the plane such as fuselage, wing, vertical fin, stabilizer and engines, is individually generated and then the whole body is assembled by the photomodeler. The maximum error in the realized airplane is about 1.4% comparing with the real one. The three-dimensional inviscid steady compressible governing equations are solved in the unstructured tetrahedron grid system, and in a finite volume method using STAR-CD when the air-plane flies at the cruise condition. The pressure distribution on the surface and the wing-tip vortices are visualized, and in addition to the aerodynamics coefficients, lift and drag are estimated.
김양균(Y.K. Kim),김성초(S.C. Kim),최종욱(J.W. Choi),김정수(J.S. Kim) 한국전산유체공학회 2008 한국전산유체공학회지 Vol.13 No.4
This research computes the viscous flow field and aerodynamics around the model of a commercial passenger airplane, Boeing 747-400, which cruises in transonic speed. The configuration was realized through the reverse engineering based on the photo scanning measurement. In results, the pressure coefficients at the several wing section on the wing surface of the airplane was described and discussed to obtain the physical meaning. The lift coefficient increased almost linearly up to 17°. Here the maximum lift occurred at 18° according to the angle of attack And the minimum drag is expected at -2°. The maximum lift coefficient occurred at the Mach number 0.89, and the drag coefficient rapidly increased after the Mach number of 0.92. Also shear-stress transport model predicts slightly lower aerodynamic coefficients than other models and Chen’s model shows the highest aerodynamic values. The aerodynamic performance of the airplane elements was presented.
김양균(Yangkyun Kim),김성초(Sungcho Kim),김정수(Jeong Soo Kim),이기만(Kee Man Ree),진학수(Haksu Jin) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Flow and aerodynamic characteristics were analyzed numerically for a commercial passenger airplane, Boeing 747-400, flying in the cruising condition. The model geometry with 100:1 in scale was obtained by the photo scanning measurement with the maximum error of 1.4% comparing with the real airplane dimension. The three-dimensional inviscid steady compressible governing equations were solved by the finite volume method in the unstructured grid system. The convective terms were treated by the Crank-Nicholson and first-order upwind schemes. In the computational results, the strong wing-tip vortices were clearly observed and the pressure contours on the airplane surface were suggested. The lift and drag forces in the wing with engines increase by 1.49% and 3.9%, respectively compared with the case without engines. The aerodynamic forces were estimated quantitatively for each element which consists of the airplane.