http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
박동훈(D.H. Park),김철완(C.W. Kim) 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.11
Performance analysis of HALE UAV propeller is carried out for comparison and analyzing the results with experimental data from wind tunnel test. Measuring device, supporting column, and test section wall of wind tunnel are chosen as major elements of interest which can yield change of measured performance in the experiment. Effect of each element is examined by comparison with result obtained by considering propeller only. The blockage effect produced by measuring device and support column is found to contribute for a small amount of increase of thrust, torque, and efficiency. Wall effect due to tunnel wall also has influence on performance increase, however, its effectiveness is smaller than the device and column. Overall effects from all elements shows approximately 1.81% and 0.68% increase of thrust and torque, respectively. Performance curves obtained by taking into account all the elements shows closer agreement with experimental data.
저속 비행체 공력해석을 위한 상용 및 오픈 소스 CFD 코드 비교
박동훈(D.H. Park),김철완(C.W. Kim),이융교(Y.G. Lee) 한국전산유체공학회 2016 한국전산유체공학회지 Vol.21 No.2
The comparison of two commercial codes(FLUENT and STAR-CCM+) and an open-source code(OpenFOAM) are carried out for the aerodynamic analysis of flight vehicles at low speeds. Tailless blended-wing-body UCAV, main wing and propeller of HALE UAV(EAV-3) are chosen as geometries for the investigation. Using the same mesh, incompressible flow simulations are carried out and the results from three different codes are compared. In the linear region, the maximum difference of lift and drag coefficients of UCAV are found to be less than 2% and 5 counts, respectively and shows good agreement with wind tunnel test data. In a stall region, however, the reliability of RANS simulation is found to become poor and the uncertainty according to code also increases. The effect of turbulence models and meshes generated from different tools are also examined. The transition model yields better results in terms of drag which are much closer to the test data. The pitching moment is confirmed to be sensitive to the existence and the location of transition. For the case of EAV-3 wing, the difference of results with k-ω SST model is increased when Reynolds number becomes low. The results for the propeller show good agreement within 1% difference of thrust. The reliability and uncertainty of three codes is found to be reasonable for the purpose of engineering use. However, the physical validity and reliability of results seem to be carefully examined when k-ω SST model is used for aerodynamic simulation at low speeds or low Reynolds number conditions.
박동훈(D H Park),신동욱(D W. Shin),류기열(K Y Ryu),김병만(B M Kim),맹승렬(S R Maeng) 한국정보과학회 1990 한국정보과학회 학술발표논문집 Vol.17 No.1
폴리모픽 언어는 프로그래머에게 많은 도움을 주지만 폴로모피즘을 제공하지 않는 언어에 비해 비효율적이라는 단점을 가지고 있다. 본 논문의 목적은 [Hanus 88]가 제안한 폴리모픽 혼 논리 명세 언어에 있어서 형 표식(type annotation)을 가능한 제거함으로써 최적화된 프로그램을 만드는 데에 있다. 기존의 [Mycroft and O'Kecfe 84]와 [Hanus 88]의 방법은 너무 제한적이어서 소수의 프로그램에 대해서 적용 가능하나 본 논문의 최적화 방법은 혼 논리를 이용한 모든 프로그램에 대해 적용 할수 있다. [Hanus 88]에서는 혼 논리외에 등식까지 고려했으나 본 논문에서는 혼 논리만을 다루겠다.