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요철이 설치된 채널 내에서 레이놀즈수와 열용량비에 따른 복합열전달 특성
송정철(Jeong Chul Song),안준(Joon Ahn),이준식(Joon Sik Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Numerical simulations are conducted to analyze conjugate heat transfer characteristics in a ribbed channel. In this simulation, the effects of Reynolds number and heat capacity of the solid channel wall on convective heat transfer are observed in the turbulent flow regime. In the case of the conducting wall against isothermal wall, the relative ratio of the thermal resistance between the solid wall and the flow field varies with Reynolds number. Thus the characteristics of the conjugate heat transfer are changed with the Reynolds number. Heat capacity ratio affects the temperature fluctuation inside solid wall. The temperature fluctuation inside the solid wall decreases with increasing the heat capacity of the solid wall so that the convective heat transfer increases. When the thermal conductivity ratio is smaller than 10, the effects of flow characteristics on heat transfer are changed.
An Immersed Boundary Method for Conjugate Heat Transfer Analysis
Jeong Chul Song(송정철),Joon Ahn(안준),Joon Sik Lee(이준식) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.11
An immersed boundary method is proposed for the analysis of conjugate problems of convective heat transfer with conducting solids. Inside the solid body, a momentum forcing is applied to set the velocity to be zero. The thermal conductivity ratio and heat capacity ratio between the solid body fluid are introduced so that the energy eqyatuib us reduced to the heat diffusion equation. At the solid-fluid interface, an effective conductivity is introduced to satisfy the heat flux continuity. The effective thermal conductivity is obtained by considering the heat balance at the interface or by using a harmonic mean formulation. The method is first validated against the analytic solution to the heat transfer problem in a fully develooped laminar channel flow with conducting solid walls. Then it has been applied to a laminar channel flow with a squared shaped obstacle to show its validity for the geometry with sharp edge. Finally the validation for a curvilinear solid body is accomplished for a laminar flow through arrayed cylinders.
송정철(Jeong Chul Song),안준(Joon Ahn),이준식(Joon Sik Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Numerical Simulations are performed to analyze the conjugate heat transfer of turbulent flow in a ribbed channel with conducting solid wall. An immersed boundary method is used to figure out the heat transfer effect in the solid region on that in the fluid region in an unitary computational domain. In order to satisfy the continuity of the heat flux at the solid-fluid interface, an effective conductivity is introduced. A large eddy simulation technique is used to predict turbulent flow. Results show that heat flux is concentrated to the rib below the channel wall and flows outward mainly around the edge of the rib. However, the local Nusselt number shows no significant difference with the pure convection case.
송정철(Jeong Chul Song),안준(Joon Ahn),이준식(Joon Sik Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
An immersed boundary method is proposed to numerically analyze the conjugate heat transfer problem. Momentum forcing is applied to set the velocity inside the solid to be zero so that the energy equation is reduced to the heat diffusion equation. An effective conductivity is introduced to satisfy the continuity of the heat flux at the interface, which is obtained by considering the heat balance at the interface or using a harmonic mean formulation. The method is validated against an analytic solution of laminar channel flow with conducting solid wall. The method is applied to two dimensional ribbed channel flow in the laminar regime.
딤플이 있는 채널 내부의 난류 열전달에 대한 큰에디모사
이영옥(Young Ok Lee),안준(Joon Ahn),송정철(Jeong Chul Song),이준식(Joon Sik Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Large eddy simulation (LES) data are presented which describe flow and heat transfer characteristics in a dimpled channel. The ratios of dimple depth and channel height to the dimple print diameter are 0.2 and 0.5, respectively. The bulk Reynolds number is 20,000. Dimples are arranged on a side of the channel in a staggered array. LES predicts quantitatively well the local Nusselt number distribution, which has not been reproduced by RANS or other turbulence models. Heat transfer rate is enhanced because all three components of velocity fluctuations are intensified along the shear layer above the recirculation bubble in the dimple. The urms is locally maximized on the wall around the downstream rim of the dimple while the wrms does around the reattachment point. The instantaneous flow and thermal fields show that the heat transfer in the dimpled channel is enhanced by the vortices generated at the shear layer.
흉곽내 병변의 진단에 절단침과 세흡인침을 이용한 경피적 침생검술의 비교
이양근(Yang Keun Rhee),곽재용(Jae Yong Kwak),송정선(Jeong Sun Song),김재헌(Jae Hean Kim),유관희(Kwan Hee You),이용철(Yong Chul Lee),한영민(Young Min Han) 대한내과학회 1996 대한내과학회지 Vol.51 No.3
N/A Objectives: Percutaneous needle biopsy in the most reliable invasive method of obtaining the confirm diagnosis of peripheral pulmonary nodule. Needle aspiration combinde with cytologic examination is being used with increasing frequency in the diagnosis of pulmonary nodules and masses. Percutaneous needle lung biopsy was done in pulmonary or mediastinal lesions using 19 Gauge fine aspiration needle or 14 Gauge cutting needle, and the results were compared with respect to diagnostic accuracy and complications. Methods: Over a periods of recent ten years. 476 patients who had localized pulmonary lesions and underwent percutaneous needle lung aspiration and biopsy using 19 Gauge fine aspiration needle or 14 Gauge cutting needle. Results: The age distribution of the patients was from sixteen to eighty-one years old. Among 467 patients, 337 patients were male and 130 patients were female. In 244 patients, sizes of the lesions were less than 4cm, in largest diameter, and in 223 patients, sizes of the lesions were larger than 4cm, but the size of the lesion was not correlated with malignancy. Diagnosic yields of the 14 Gauge cutting needle and the 19 Gauge fine needle were 88.3% and 78.3% respectively. Success rate of benigm and malignant lesion was more higher in 14 Gauge cutting needle than 19 Gauge fine aspiration needle. Common diseases were priamry lung cancer, tuberculoma, abscess in order of frequency. The complications of procedure were mild pneumothorax in ten patients, mild hemoptysis in six patients and subcutaneous emphysema in one patient. With Cutting needle and aspiration needle, complication rate was 2.73% and 2.36%, respectively. Conclusion: Percutaenous needle lung biopsy with cutting needle under the chest computed tomogram and biplane fluoroscopy had lower complication rate and high diagnostic success rate for the intrathoracic lesions
경피적 세흡인침과 절단침을 이용한 흉곽내 병변의 진단적 가치에 대한 연구
이양근,곽재용,송정선,김재헌,유관희,이용철,박성광,백홍선,강성귀 의과학연구소 1996 全北醫大論文集 Vol.20 No.1
Percutaneous needle biopsy is most reliabel noninbasive method of obtaining the confirm diagnosis of peripheral pulmonary nodule. Needle aspiration combined with cytologic examination is being used with increasing frequency in the diagnosis of pulmonary nodules and masses. Percutaneous needle lung biopsy way done in pulmonary or mediastinal lesions using 19 Gauge fine aspiration needle or 14 Gauge cutting needle, and the results were compared with respect to diagnostic accuracy and complications. Over a periods of recent ten years,476 patients who had localized pulmonary lesions and underwent percutaneous needle lung aspiration and biopsy using 19 Gauge fine aspiration needle or 14 Gauge cutting needle. The age distribution of the patients was from sixteen to eighty-one years old. Among 467 patients, 337 patients were male and 130 patients were female. In 244 patients, the lesion were less than 4cm in largest diameter, and in 223 patients, the lesion were larger than 4cm, but the size of the lesion was not correlated with malignancy. Diagnosic yields of the 14 Gauge cutting needle and the 19 Gauge fine needle were 88.3% and 76.8% respectively. Success rate of benign and malignant lesion were more higher in 14 Gauge cutting needle than 19 Gauge fine aspiration needle. Common diseases were primary lung cancer, tuberculoma, abscess in order of frequency. The complications of procedure were mild pneumothorax in ten patients, mild hemoptysis in six patients and subcutaneous emphysema in one patients. With Cutting needle and aspiration needle, complication rate were 2.73% and 2.36%, respecitvely. Percutaneous needle lung biopsy with cutting needle under the chest computed tomogram and biplane fluroscopy had lower complication rate and high diagnostic success rate for the intrathoracic lesions.
천기태,김현중,송정선,권철,이수택,김대곤,안득수 의과학연구소 1994 全北醫大論文集 Vol.18 No.2
Eosinophilic gastroenteritis is a rare disease of gastrointestinal tract and includes three major clinical patterns of mucosal, muscle layer, and subserosal disease. A 53-year-man was presented with bloody diarrhea, tenesmus and marked eosinophilia in peripheral blood. The mucosal type of eosinophilic gastroenteritis was confirmed by mucosal biopsy on the sigmoid and descending colon. The patient was rapidly improved with oral prednisolone administration. We report this case with the review of relevant literature.