전산해석에 의한 일체형 원자로용 주냉각재 펌프의 성능분석

오형우,윤의수,박상진 대한기계학회 2006 大韓機械學會論文集B Vol.30 No.8

원심형 임펠러에 대한 이구역 모델링

오형우,정명균,김재원,Oh, Hyoung Woo,Chung, Myung Kyoon,Kim, Jae Won 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.9

This paper presents a systematic two-zone modeling for reliable performance prediction of centrifugal compressors. In order to improve the predictive capability, a modified jet slip factor is developed and new corrections for the wake flow deviation and mass fraction are suggested based on the comprehensive experimental data of the three Eckardt impellers. The proposed two-zone modeling is tested against nine sets of measured data of centrifugal compressors. The results are also compared with those obtained by the mean streamline analysis. It was found that the predictions by the present two-zone modeling agree fairly well with experimental data for a variety of centrifugal compressors over the wide operating conditions.

원심 압축기의 성능 예측 및 손실 해석

오형우,윤의수,정명균,O, Hyeong-U,Yun, Ui-Su,Jeong, Myeong-Gyun 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.6

The present study has tested most of loss models previously published in the open literature and found an optimum set of empirical loss models for a reliable performance prediction of centrifugal compressors. In order to improve the prediction of efficiency curves, this paper recommends a modified parasitic loss model. Predicted performance curves by the proposed optimum set agree fairly well with experimental data for a variety of centrifugal compressors. The prediction method developed through this study can serve as a tool for preliminary design and assist the understanding of the operational characteristics of general purpose centrifugal compressors.

소수력 발전용 수력터빈의 최적설계 : 제1부 - 전산해석코드의 해석성능 검증

오형우 忠州大學校 2008 한국교통대학교 논문집 Vol.43 No.-

The hydraulic design optimization and performance analysis of a bulb-type tubular turbine for small hydropower generation has been carried out using the well-established commercial computational fluid dynamics (CFD) code. In the present study, as a part of ongoing research works, the predictive capability of the CFD code adopted in this study was validated in comparison with the experimental data for a Francis, reaction, turbine. Predicted performance curves agree fairly well with the test results over the entire operating condition. The prediction method presented herein can be used efficiently as a reliable tool for the hydrodynamic design optimization and performance analysis of a hydraulic turbine for small hydropower generation.

원심펌프임펠러의 캐비테이션 성능예측

오형우 한국교통대학교 2014 한국교통대학교 논문집 Vol.49 No.-

A numerical simulation based on the validated computational fluid dynamics code has been carried out to analyze the hydrodynamic performance characteristics of a laboratory centrifugal pump impeller. The cavitation performance of the centrifugal pump impeller has also been investigated over the normal operating flow range. The computational analysis method including the prediction of the suction performance characteristics at the design and off-design conditions can be effectively applied to the hydraulic design optimization and assist in the understanding of the operational characteristics of centrifugal pump impellers.

로켓추진용 연료펌프의 평균유선해석방법

오형우 忠州大學校 2004 한국교통대학교 논문집 Vol.39 No.1

High pressure pumps with the low net positive suction head are widely used for the rocket propulsion turbopump systems, which have an inducer and operate at high rotating speeds. In this paper, a mean streamline analysis method has been established for the preliminary design and performance prediction of pumps having an inducer with/without cavitating conditions on/off-design points. Predicted performances by the present method herein are in good agreement with experimental results for cavitating and non-cavitating conditions. The established mean streamline method can be effectively used for the conceptual design and performance analysis of high speed pumps having inducer, impeller and volute.

즉시 하중 임프란트에서 성공률과 시기에 따른 임프란트 변연골 높이 변화

吳炯宇,權鍾瑨 치과연구사 2006 치과연구 Vol.60 No.6

폐색성 심근 경색: 백서 모델에서의 CT 관류영상

오형우,김동훈,변주남,김영숙 대한영상의학회 2007 대한영상의학회지 Vol.56 No.3

Purpose: To test whether cardiac multidetector CT (MDCT) perfusion imaging can accurately delineate an irreversibly damaged myocardium in animals with an occlusive myocardial infarction. Materials and Methods: In 16 rats, the left anterior descending coronary arteries were ligated distal to its first diagonal artery after a thoracotomy. Thirty minutes after the procedure, 16-slice MDCT (Sensation 16, Siemens, Erlangen, Germany) was performed and delayed images were obtained up to 5 minutes after injecting the contrast agent (0.2 mL/100g, 0.5 mL/sec). Ten rats were re-examined one week later. After CT scanning, the rats were sacrificed and their hearts were extirpated for 2,3,5-triphenyltetrazolium chloride (TTC) histochemical staining. The stained slices were compared with the CT images. The CT number (HU) of the infarct and non-infarct areas were estimated from the contrast ratio (CR). Results: The CT attenuation in the infarct area was significantly lower than that in the normal myocardium. Quantitative analysis of the CT attenuation revealed a significant difference in the CR and CT attenuation of the infarct and reference areas (0.48±0.12 vs 0.64±0.13, p<0.05, 163±46 HU vs 216±56 HU, p<0.05). However, there were no significant differences in the CT numbers between the infarct and non-infarct areas on the one-week follow-up. Conclusion: A perfusion defect on MDCT indicates the myocardial damage in an animal model with occlusive myocardial infarction. 목적: 폐색성 심근 경색에서 심장 CT 관류영상이 비가역적 심근손상을 영상화할 수 있는지 알아보고자 하였다. 대상과 방법: 개흉술 후 첫 번째 대각분지 이하의 왼앞내림 관상동맥을 결찰한 16마리의 백서를 대상으로 하였다. 관상동맥 폐색 후 30분째 16열 다절편 CT(Sensation 16, Siemens, Erlangen, Germany)를 이용하여 영상을 얻었으며 5분 후 추가 지연 영상을 얻었다. 10마리의 백서는 일주일 후 같은 방법의 영상을 얻었다. CT 후 백서를 희생시켜 심장을 꺼낸 후 3 mm두께의 절편을 만든 뒤 2,3,5-triphenyltetrazolium chloride(TTC)로 염색하였다. 염색된 절편을 CT 영상과 비교하였다. CT 상 경색부위와 비 경색부위에 대해 CT 수치(HU)의 대조 비를 측정하였다. 결과: 조영 직후 TTC 소견상 경색이 발견된 부위의 CT 값은 정상부위보다 의미 있게 낮은 수치를 보였다. CT 수치의 양적인 비교에서 경색부위는 비 경색부위와 비교하여 CT 수치의 대조 비, CT 수치 절대값에서 의미 있는 차이를 보였다(0.48±0.12 vs. 0.64±0.13, p < 0.05, 163±46 HU vs. 216±56 HU, p < 0.05). 1주일 후 추적검사에서는 경색영역과 정상부위와의 CT 값에서 유의한 차이를 발견하지 못했다. 결론: 비가역성 심근 경색의 백서 모델에서 CT 관류영상은 폐색성 심근 경색을 명확히 구분할 수 있음을 알 수 있으며, 관류 결손 부위는 심근 손상이 있는 영역을 의미한다.

원심펌프임펠러의 성능해석

오형우 韓國交通大學校 2013 한국교통대학교 논문집 Vol.48 No.-

This paper is aimed at analyzing the hydraulic performance characteristics of a laboratory centrifugal pump impeller for which many experimental data are available in the open literature. The detailed flow field in the pump impeller and its performance curves are investigated by the validated commercial computational fluid dynamics (CFD) code adopted in the present study. Predicted performance characteristics agree very well with the test data at the nominal and partial flow rate conditions. The performance analysis method presented herein can be effectively used as a tool for the hydraulic design optimization and assist in the understanding of the operational characteristics of centrifugal pump impellers.

펠턴터빈의 설계 및 성능해석

오형우 忠州大學校 2012 한국교통대학교 논문집 Vol.47 No.-

This paper presents the hydraulic design and performance analysis of a Pelton turbine for the small-scale hydropower generation. The usable information about the preliminary design process was proposed to determine the overall geometric data for the Pelton turbine. In order to obtain the hydraulically efficient configuration of the Pelton turbine, the well-established commercial computational fluid dynamics (CFD) codes were incorporated considering detailed flow dynamic phenomena in the turbine runner. A prototype of Pelton turbine was developed by the present design and analysis method, and its hydraulic performance will be validated in the near future study. The design and performance analysis method presented herein can be effectively used as a tool for the practical design optimization and assist in the understanding of the operational characteristics of Pelton turbines.