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남청도,Nam, Cheong-Do 한국마린엔지니어링학회 1991 한국마린엔지니어링학회지 Vol.15 No.3
This paper describes characteristics of the flow pattern of the flow past a rectangular cylinder experimentally investigated. The width-to-length ratio of the section varried from 2 to4. For the statistical treatment, autocorrelation coefficient, probability density function and power spectral density function are obtained by the digital processing technic through on-line system with a hot wire anemometer. As a results, it was found that strong periodic coherent eddies structure is sustained to about 20H downstream from the cylinder. And nearer the cylinder in the wake, the number of turbulent eddies of a large scale coherent structure are comparatively much more dominant than that of a small scale one. By the analysis of power spectrum, It was cleared that there exists a certain range of the width to length ratio between 2.5 and 3 of which the flow pattern changes abruptly with a sudden discontinuity in Strouhal number.
퓐이 나선형으로 부착된 원주희 후류에 관한 실험적 연구
남청도(C.D.Nam),민경용(K.Y.Min) 한국해양대학교 해사산업연구소 2001 海事産業硏究所論文集 Vol.11 No.-
The characteristics of two dimensional turbulent wake flow past a circular cylinder with helical fin was investigated by using X type hot wire anemometer for the experiment. As a result it is cleared that Karman vortex sheds from the cylinder with helical fin as the same as a circular cylinder or a rectangular cylinder. Turbulent characteristics such as the distribution of the mean velocity, turbulent kinetic energy, autocorrelation coefficient and its spectrum of them are suggested. It is also found that the width of the wake flow become larger as the pitch of the fin increased, and the frequency of vortex shedding is on the decrease.
퓐이 나선형으로 부착된 원주의 후류에 관한 실험적 연구
남청도(C. D. Nam),안윤수(Y. S. Ahn) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.4
The characteristics of two dimensional turbulent wake flow past a circular cylinder with helical fin was investigated by using X type hot wire anemometer for the experiment. As a result it is cleared that Karman vortex sheds from the cylinder with helical fin as the same as a circular cylinder or a rectangular cylinder. Turbulent characteristics such as the distribution of the mean velocity, turbulent kinetic energy, autocorrelation coefficient and its spectrum of them are suggested. It is also found that the width of the wake flow become larger as the pitch of the fin increased, and the frequency of vortex shedding is on the decrease.
남청도(Chung-Do Nam),김정만(Jung-Man Kim) 한국항해항만학회 2010 한국항해항만학회 학술대회논문집 Vol.2010 No.추계
최근 지구온난화 영향 등으로 인하여 북극해의 해빙이 가속화 되고 있어 북극항로의 상용화가 예상보다 빨라질 전망이다. 하절기 북극해의 얼음 면적은 1979년 위성관측이 개시된 이래 약 40%정도로 줄었다. 북극항로가 상업적으로 이용되기 위해서는 경제성 문제 이전에 북극항로중 일부가 특정국가 배타적으로 사용하는 문제가 해결되어야 하며, 다음으로 선박운항 기술적 요인으로서 부빙들이 움직이고 있는 기후조건에 맞는 특수선박의 건조가 필요하며 또한 이들 선박을 북극해에서 운항할 수 있는 선원들의 교육 프로그램의 이수 외에도 관련 연안국과의 협력으로 국제적인 공인이 이루어져야 할 것이다. 그 밖에 북극항로 정보시스템개발에 대해서도 연구가 이루어져야 할 것이다. It is prospected that commercialization of the Arctic route come to faster than an anticipation due to acceleration of the melting of Arctic ice as a result of global warmness and etc. Since 1979 from the start of the satellite observation, the ice areas of the Arctic ocean came to decrease about 40 % in summer season For the commercial use of the Arctic route, it must be settled some problems including the navigation for the vessels in the EEZ of the related nations before considering about economic basis. It is also needed to build special ships which satisfy to the condition of the Arctic climate for the technical factors of ship handling and should be carried out completion of the special educational program to be approved for the seamen through the cooperation with the coastal nations. The information system for the Arctic route should be developed.
남상현(Sang-Hyun Nam),김유택(You-Taek Kim),최영도(Young-Do Choi),남청도(Chung-Do Nam),이영호(Young-Ho Lee) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회 학술대회 논문집 Vol.2007 No.-
Micro hydraulic power generation which has output of less or equal to 100㎾ is attracting considerable attention. This is because of its small, simple, renewable, and large amount of energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use reducing of a valve at the end of the pipeline, is collected by turbine in the hydropower generator. In this study, we investigated the influence of the number of blades on the characteristics of small hydroturbine.
남상현(Sang-Hyun Nam),김유택(You-Taek Kim),최영도(Young-Do Choi),남청도(Chung-Do Nam),이영호(Young-Ho Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Micro hydraulic power generation of which the output is less or equal to a 100㎾ is attracting considerable attention. This is because of its small, simple, renewable, and abundant energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Moreover influences of pressure and velocity distributions with the variations of runner vane angle on turbine performance are investigated by using a commercial CFD code.
김유택,남청도,이영호,Kim, You-Taek,Nam, Chung-Do,Lee, Young-Ho 한국유체기계학회 2001 한국유체기계학회 논문집 Vol.4 No.4
Pumps arre used extensively for transporting fluid in many ships. However, the present state of pumps used in the large merchant ships has not been studied. In this paper, we have reported the general description of the operating pumps according to the different ship types(Bulk, Container, Car-Carrier, Tanker, LNG). Moreover, the pump total powers are compared with the main engine Normal Continuous Rating power and the pump total weights are also compared with the ship deadweight.
BEMT를 적용한 20kW 수평축 풍력터빈 형상설계 및 성능해석
강호근,남청도,이영호,김범석,Kang, Ho-Keun,Nam, Cheong-Do,Lee, Young-Ho,Kim, Beom-Seok 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.6
The optimum design and the performance analysis software called POSEIDON for the HAWT (Horizontal Axis Wind Turbine) is developed by use of BEMT, which is the standard computational technique for prediction of power curves of wind turbines. The Prandtl's tip loss theory is adopted to consider the blade tip loss. The lift and the drag coefficient of S-809 airfoil are predicted via X-FOIL and the post stall characteristics of S-809 also are estimated by the Viterna's equations.$^{[13]}$ All the predicted aerodynamic characteristics are fairly well agreed with the wind tunnel test results. performed by Sommers in Delft university of technology. The rated power of the testing rotor is 20kW(FIL-20) at design conditions. The experimental aerodynamic parameters and the X-FOIL data are used for the power Prediction of the FIL-20 respectively The comparison results shows good agreement in power prediction.
김유택(You-Taek Kim),남청도(Cheong-Do Nam),강호근(Ho-Keun Kang),이영호(Young-Ho Lee) 한국유체기계학회 2004 유체기계 연구개발 발표회 논문집 Vol.- No.-
A screw-type centrifugal pump was manufactured to cany solids primarily and its impeller has a wide flow passage. However, the effect of flow passage shape on delay of the choke due to entrained air has not been clarified yet. Moreover, because its impeller has a particular shape, only few studies have tried to clarify the pump performance and details of internal flow pattern of that pump. For that reason, we carried out the pump performance experiment under air-water two-phase flow condition with different impeller tip clearances, pump rotational speeds and void fractions by using a small screw-type centrifugal pump designed to acquire basic data. In a general centrifugal pump, it was reported that loss of pump head from single-phase flow to the choke due to air entrainment near the best efficiency point was large. However, the loss near the best efficient point in a screw-type centrifugal pump became less than that in a general centrifugal pump.