• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.30-34
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• 2001

In the present study, we studied the method of predicting the on-design and on-design point performance of axial flow fan with adjustable pitch blades. With the change of stagger angle of axial flow fan with adjustable pitch blade, flow rate and pressure can be changed. Because of this merit adjustable pitch fans are used in many industrial facility. When changing stagger angle or estimating the performance at a wide range of off-design condition, incidence angle changes greatly as the flow rate changes. Therefore, the deviation angle at the blade exit is estimated by the correlation considering the effects of blade design, incidence angle variation. In the loss model, we used known pressure loss model for blade boundary layer and wake, secondary flow, endwall boundary layer and tip leakage flow. The results of modified deviation angle model and experiment were compared for the usefulness of the modified model.

• 한국유체기계학회 논문집
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• 제5권1호
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• pp.33-41
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• 2002

Low NPSH and high pressure pumps we widely used for turbopump systems, which have an inducer and operate at high rotating speeds. In this paper, a meanline method has been established for the preliminary design and performance prediction of pumps having an inducer for cavitating or non-cavitating conditions at design or off-design points. The method was applied for the performance prediction of a fuel pump. Predicted performances by the method are shown to be in good agreement with experimental results for cavitating and non-cavitating conditions. The established meanline method can be used for the performance prediction and preliminary design of high speed pumps which have a inducer, impeller and volute.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.426-431
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• 2011

The quality of performance evaluation on engineering consultants that provide design-related technical services is difficult to be measured, and only a handful of papers discussed the quality during the design stage. Although design cost is relatively far less than construction cost for a project, the decisions made in the design phase have a significant impact on the final products of the project, especially for large public construction projects. Therefore, this research focuses on reviewing and then establishing a performance evaluation framework for the consulting firms that execute detailed design and provide technical services for the Taipei Rapid Transit Systems (TRTS). By interviewing experts, this study first established a set of indicators to evaluate these firms' performance. Then, those indicators were incorporated into the four aspects of balanced scorecard (BSC) to establish the architecture of the evaluation mechanism. The weight of each indicator was calculated by analytic hierarchy process (AHP) from a survey conducted among experts. The results showed that the top-three indicators were quantity take-off, functions conformity, and budgeting. The framework of performance evaluation established by this study can be applied to measure service performance during the design stage. It not only facilitates the monitoring of consulting firms, but also helps to reduce unnecessary change orders and disputes during the construction stage.

• 한국유체기계학회 논문집
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• 제11권6호
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• pp.7-17
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• 2008

Fan performances are obtained with various tip clearance gaps and stagger angles of the rotor. A tested fan is an axial-type fan of which the casing diameter is 806 mm. Two different rotors are applied to this test. One is designed on the basis of the free vortex method along the radial direction and the other is designed using the forced vortex method. The operating conditions are varied to the ultimate off-design point as well as the deign point. Overall efficiency, total pressure and input power are compared with the tip clearance gaps and different stagger angle. The experimental results show that changing of the stagger angle has minor influence to the performance when the same rotor is applied. When the tip clearance gap is less than 5% of the rotor span, the overall efficiency, total pressure loss and input power reduction are varied linearly with the variation of the tip clearance gaps. On the design point, the overall efficiency is decreased to the rate of 2.8-2.9 to the increasing of the tip clearance, but the changing rate of the overall efficiency is alleviated when the fan operates at off-design points. In particular, this rate is more quickly declined on a fan with the rotor designed using the forced vortex method. The result of the total pressure shows that the pressure reduction rate is a 0.08-0.1 according to the tip clearance, and additionally the input power reduction rate is a 0.045-0.065 at design point.

• 한국항공우주학회지
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• 제46권6호
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• pp.496-502
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• 2018

본 연구에서는 이젝터의 주유동과 부유동의 모멘텀에 따라 형성되는 공기역학적 목에 관한 현상을 관찰하기 위하여 실험, 해석적 연구를 수행하였다. 상온 실험과 상용프로그램인 FLUENT를 이용한 해석을 통하여 주유동의 유량과 이젝터 실린더의 목 직경의 변화에 따른 성능으로 이젝터 성능의 주요 변수인 공기역학적 목의 평형구간을 관찰하였다. 결과적으로 기준 이젝터에서 유량비 변수는 0.33~1.167(탈설계/설계)의 범위, 실린더 목 직경 변수는 1~1.17(탈설계/설계 면적비)의 범위에서 성능 구현이 확인되었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.265-267
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• 2013

Tire labeling is an important issue to reduce $CO_2$ and to secure the safety of tire/vehicle on wet road. A basic study on the effects of tire basic stiffness design on tire labeling performance has been done through experimental test. The pass-by noise is affected by tire structural design. The tire with lower side part stiffness and lower tread part stiffness has the lowest PBN level and the best wet grip. And the tire with higher tread part stiffness and higher side part stiffness has the better RR performance. Also it is observed that the trade-off between RR and wet grip exists for various tire stiffness design.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.432-439
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• 1999

In this paper, an off-line programming(OLP) system is presented as the three dimensional graphic simulator and one of the human-robot interface systems for industrial robots. The OLP system has been especially developed to testify robot programs visually using three dimensional geometric modeling and graphics technologies in personal computes. A special feature is its capability of collision detection and of comparing performance of control algorithms. This paper places the focus on the structure and major characteristic of OLP system.

• 한국유체기계학회 논문집
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• 제8권2호
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• pp.31-38
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• 2005

A low NPSH and high pressure fuel pump has been designed for a turbopump system. The fuel pump has an axial inducer and a centrifugal impeller. A meanline method has been established for the preliminary design and performance prediction of pumps at design or off-design points. KeRC(Kelyish Research Center) carried out a model testing of the fuel pump with water as a working fluid at the reduced speed. Predicted performances by the method are shown to be in good agreement with experimental results for cavitating and non-cavitating conditions. The established meanline method can be used for the performance prediction and preliminary design of high speed pumps which have a inducer, impeller and volute. In the current study, the three dimensional viscous flow in the fuel pump was investigated through numerical computation. A modified design of the fuel pump was generated to improve pump performance by utilizing CFD results. The modified fuel pump was experimentally tested by ROTEM and KARI(Korea Aerospace Research Institute). The measured non-cavitating and cavitating performance showed a good agreement with designed performance.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.341-346
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• 2004

A low NPSH and high pressure fuel pump has been designed for a turbopump system. The fuel pump has an axial inducer and a centrifugal impeller. A meanline method has been established for the preliminary design and performance prediction of pumps at design or off-design points. KeRC carried out a model testing of the fuel pump with water as a working fluid at the reduced speed. Predicted performances by the method are shown to be in good agreement with experimental results for cavitating and non-cavitating conditions. The established meanline method can be used for the performance prediction and preliminary design of high speed pumps which have a inducer, impeller and volute. In the current study, the three dimensional viscous flow in the fuel pump was investigated through numerical computation. A modified design of the fuel pun was generated to improve pump performance by utilizing CFD results. The modified fuel pump was experimentally tested by ROTEM and KARI. The measured non-cavitating and cavitating performance showed a good agreement with designed performance.

• 한국콘텐츠학회논문지
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• 제9권12호
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• pp.537-545
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• 2009

본 논문에서는 이동통신망을 위한 효율적인 멀티캐스트 인과순서 알고리즘과 채널전환 프로토콜을 제안하였다. 메시지 전달 순서를 유지하기 위한 제어정보의 크기는 이동통신망에서의 채널전환과 메시지 전송성능에 큰 영향을 주므로 제어정보의 크기를 최소화할 필요가 있다. 이를 위해 모든 유효한 통신패턴을 분석하여 인과순서를 유지하는데 필수적이지 않은 중복정보를 가능한 이른 시기에 찾아내어 제거하고, 전송되는 제어정보를 최소화하는 채널전환 프로토콜을 사용하였다. 시뮬레이션을 통해 제안한 알고리즘이 기존의 알고리즘보다 더 좋은 성능을 보임을 보였다.