• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.441-446
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• 2000

The experiments of the Aerodynamic characteristics of a counter-rotating axial fan were carried out. The performance tests of a single and a counter-rotating axial fan were carried out based on the Korean Standard Testing Methods for Turbo-fans and Blowers(KS B 6311). The performances of single and counter-rotating axial fans were obtained and compared with each other. The flow fields of a counter-rotating axial fan at the peak efficiency point were measured using a five-hole probe. As a result, compared with the performance of a single-rotating axial fan, that of a counter-rotating axial fan was superior. And it is confirmed that most of the swirl flow generated by the front rotor was eliminated by the rear rotor.

• 한국유체기계학회 논문집
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• 제4권3호
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• pp.46-52
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• 2001

This paper describes a turbine test program conducted at Seoul National University(SNU). To measure blades' aerodynamic performance, either linear(2-Dimensional) or annular(3-Dimensional) cascades are often used. However, neither cascade can consider effects such as those due to rotation or rotor-stator interaction. Therefore, a rotating test facility for axial turbines has been designed and built at SNU, and its description is given in this paper. The results from an axial turbine performance test are presented. At the design point, the measured efficiency agrees with the efficiency predicted by a meanline analysis. At off design points, however, the measured and predicted efficiencies diverge. The most likely cause is hypothesized to be the inaccuracy of correlations used in the meanline analysis at off design points.

• Journal of Advanced Marine Engineering and Technology
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• 제34권1호
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• pp.84-91
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• 2010

The centrifugal oil purifier is used in ships for purifying the engine lubrication oil. The momentum needed for the rotation of the cylindrical chamber is obtained by jet injections. The dust particles in the oil are separated by the centrifugal forces moving to the inner wall of the rotating cylindrical chamber body. The dust particles are eliminated when the particles are adsorbed onto the surface of the inner wall of the chamber body. The flow characteristics and the physical behaviours of particles in this centrifugal oil purifier have been investigated numerically and the filtration efficiencies have been evaluated. For the calculations, a commercial code has been used and the SST k-${\omega}$ turbulence model has been adopted. The MRF (Multiple Reference Frame) method has been introduced to consider the rotating effect of the flows. Under various variables, such as particle size, particle density and rotating speed, the filtration efficiencies have been evaluated. It has been verified that the filtration efficiency is increased with the increments of the particle size, the particle density and the rotating speed of the cylindrical chamber.

• Journal of Advanced Marine Engineering and Technology
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• 제38권10호
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• pp.1251-1256
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• 2014

The use of lubrication oil is of many purposes and one among them is to drive the engine mounted on a ship. Hence the supply of clean lubrication oil is important. And an oil purifier is one of key components in marine diesel engines. At present, the element type full-flow oil filter has been widely used for cleaning the engine oil. The self-driven centrifugal oil purifier is a device which is used to remove the impurities in lubrication oil using a jet flow. The flow characteristics and the physical behaviors of particles in this self-driven oil purifier were investigated numerically and the filtration efficiencies were evaluated. For calculations, a Computational Fluid Dynamics method is used and the Shear Stress Transport turbulence model has been adopted. The Multi Frames of Reference method is used to consider the rotating effect of the flows. The influence of centrifugal forcehas been numerically investigatedto improve filtration efficiency of tiny particles. As a result of this research, it was found that the particle filtration efficiency using the only center axis rotating and outer wall rotating system are higher than that of the fully rotating system in the self-driven oil purifier.

• 한국해양공학회지
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• 제23권5호
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• pp.25-31
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• 2009

The most important component of wind turbine is rotor blades. The developing method of wind turbine was focused on design of rotor blade. By the way, the design of a rotating body is more decisive process in order to adjust the performance of wind turbine. For instance, the design allows the designer to specify the wind characteristics derived by topographical map. The iterative solver is then used to adjust one of the selected inputs so that the desired rotating performance which is directly related to power generating capacity and efficiency is achieved. Furthermore, in order to save the money for manufacturing the rotor blades and to decrease the maintenance fee of wind power generation plant, while decelerating the cut-in speed of rotor. Therefore, the design and manufacturing of rotating body is understood as a substantial technology of wind power generation plant development. The aiming of this study is building-up the profitable approach to designing of rotating body as a system for the wind power generation plant. The process was conducted in two steps. Firstly, general designing and it’s serial testing of rotating body for voltage measurement. Secondly, the serial test results above were examined with the CFD code. Then, the analysis is made on the basis of amount of electricity generated by rotor-blades and of cut-in speed of generator.

• Journal of Advanced Marine Engineering and Technology
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• 제38권2호
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• pp.147-153
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• 2014

The centrifugal oil purifier is used in an engine for lubrication and to remove impurities. The momentum needed for the rotation of the cylindrical chamber is obtained by jet injections. An impure particle in the oil is separated by the centrifugal forces moving to the inner wall of the rotating cylindrical chamber body. The dust particles are eliminated when the particles are absorbed onto the surface of the inner wall of the chamber body. The flow characteristics and the physical behaviors of particles in this centrifugal oil purifier were investigated numerically and the filtration efficiencies was evaluated. For calculations, a commercial code is used and the SST (Shear Stress Transport) turbulence model has been adopted. The MFR (Multi Frames of Reference) method is introduced to consider the rotating effect of the flows. Under various variables, such as particle size, particle density and rotating speed, the filtration efficiencies are evaluated. It has been verified that the filtration efficiency is increased with the increments in the particle size, the particle density and the rotating speed of the cylindrical chamber.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.144-148
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• 2006

Characteristics of a plasma reactor for partial oxidation of methane, especially focused on the role and effectiveness of plasma chemistry, is investigated. Partial oxidation of methane is investigated using a rotating arc which is a three dimensional version of a typical glidingarc. The rotating arc has both the characteristics of equilibrium and non-equilibrium plasma. Non-equilibrium characteristics of the rotating gliding arc can be increased by rotating an elongated arc string attached at both the tip of inner electrode and the edge of outer electrode. In this way, plasma chemistry can be enhanced and hydrogen selectivity can reach almost 100% that is much higher than thermal equilibrium condition. As a result, the present study enables the strategic approach of the plasma reforming process by means of appropriate reactor design to maximize plasma effect and resulting in maximized reaction efficiency.

• Journal of Biosystems Engineering
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• 제26권2호
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• pp.131-140
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• 2001

This study was conducted to develop a garlic separator which could to reduce the labor in preparation of seeding. After consideration of the design criteria of a garlic separator such as no additional conveying device, simple construction and operation, enhancement of separating efficiency, reduction of damage, degree a rotating corn type garlic separator was designed. The effects of design parameters such as height and angle of the inner and outer corns, rotating speed of inner corn on the separating performance of the prototype were estimated. In performance was compared with manual work. The results are summarized as follows. 1. Garlic bulbs were separated by a spiral movement in the gap between inner rotating corn and outer fixed corn. At constant feed rate of garlic bulbs, the capacity of garlic separation increased with increase of rotating speed of inner corn. Especially, the capacity was very high at the rotating speeds of 300 and 400rpm. 2. The damage degree of separated garlics increased with rotating speed of corn within 10%. Above 300rpm, separability of Uisung garlic was about 100% and incomplete separation of Namdo garlic was within 2%. 3. The capacity of prototype garlic separator developed in this study was 30 times as large as that of human being.

• 핵의학기술
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• 제14권1호
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• pp.90-93
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• 2010

서울아산병원 핵의학과에서는 $^{99m}Tc$-RBC의 표지 효율을 높이기 위한 방법으로 기존의 변형 체외 표지 방법(modified in-vitro)의 일부를 변형하여 개선시킨 AMC 적혈구 표지 방법을 제시한 바 있다. 그러나 AMC 적혈구 표지 방법은 3-5분의 원심분리 과정을 한 번 더 시행함으로써 기존의 변형체외 표지 방법보다 추가적인 노력과 시간을 필요로 한다. 이에 본 연구는 AMC 적혈구 표지 방법을 통한 $^{99m}Tc$-RBC표지 시 교반 시간을 줄임으로써 추가 시간 소요의 문제점을 보완하고 안정적인 표지 효율을 유지하는 것에 목적을 두고 연구를 시행하였다. 2009년 5월부터 9월까지 서울아산병원 핵의학과에서 $^{99m}Tc$-RBC를 사용하여 검사받은 환자를 무작위로 선정하여 실험 참여에 동의한 30명을 대상으로 하였다. 환자당 1 cc의 ACD에 5 cc의 혈액을 채취하여 4개의 혈액 샘플을 만들었으며, AMC적혈구 표지 방법을 사용하여 표지를 진행하였다. 이때 교반시간을 5분, 10분, 15분, 20분으로 다르게 하여 각각의 표지효율을 산출하였고 그에 따른 차이를 비교하였다. AMC 적혈구 표지 방법을 사용하여 교반 시간 차이에 따른 $^{99m}Tc$-RBC 표지 효율을 비교한 결과, 각각의 표지 효율은 5분에서 $92.3{\pm}5.0%$, 10분에서 $95.9{\pm}5.0%$, 15분에서 $97.4{\pm}4.9%$, 20분에서 $97.7{\pm}4.8%$였다. 일원분산분석(One- Way ANOVA)을 사용하여 교반 시간 변화에 따른 표지 효율의 차이를 분석하고, Duncan 방법으로 사후 검증하였다. 5분의 교반 시간에서는 표지 효율이 상대적으로 낮았으며, 그 이상에서의 표지 효율은 통계학적으로 유의한 차이가 없었다. AMC 적혈구 표지 방법은 기존의 변형 표지 방법과 비교할 때 원심분리 과정을 한 번 더 거쳐 혈장 성분을 제거함으로써 RBC가 $^{99m}TcO4^-$와 결합하는 데 더 유리한 환경을 제공할 수 있다. 변형 체외 표지 방법을 사용할 경우 20분 정도의 교반 시간을 주어야 안정적인 표지 효율을 획득할 수 있는 반면, AMC 적혈구 표지 방법을 적용할 경우 교반 시간을 10분만 시행하여도 해당 검사에서 원하는 충분한 표지효율을 얻을 수 있었다. 교반 시간의 감소는 원심 분리 과정을 한 번 더 거쳐야 하는 AMC 적혈구 표지 방법을 보완할 수 있으며, 보다 빠른 시간 내에 $^{99m}Tc$-RBC의 표지를 가능하게 하여 G-I bleeding과 같은 응급 환자에게 좀 더 빠른 검사를 제공할 수 있을 것이라 사료된다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제1권1호
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• pp.29-38
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• 2009

A ship's screw-propeller produces thrust by rotation and, at the same time, generates rotational flow behind the propeller. This rotational flow has no contribution to the generation of thrust, but instead produces energy loss. By recovering part of the lost energy in the rotational flow, therefore, it is possible to improve the propulsion efficiency. The contra-rotating propeller (CRP) system is the representing example of such devices. Unfortunately, however, neither a design method nor a full-scale performance prediction procedure for the CRP system has been well established yet. The authors have long performed studies on the CRP system, and some of the results from the authors' studies shall be presented and discussed.