• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.213-216
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• 2006

This paper was a study about noise reduction through flow stabilization in duct using experimental method and numerical analysis at the same time. To determine the fan's type three kinds of fans(axial fan, centrifugal fan, and axial fan with centrifugal type blades) was examined to investigate the suitability for in-line duct. As a result, under the equal number of rotation 2000 RPM, performance of an axial fan with centrifugal type blades was the most superior by 55dBA at 4.3CMM among other fans. After this, analyzed the results of the numerical analysis to find out the optimum design of pitch angle such as $0^{\circ}$, $10^{\circ}$, $15^{\circ}$ and $20^{\circ}$. The intensity of turbulence was low when pitch angle was $15^{\circ}$ and air volume became peak by 5.08 CMM. It was observed that axis component of velocity increased gradually when pitch angle increased from $0^{\circ}$ to $20^{\circ}$, and embodied noise reduction and improvement of air flow rate through flow stabilization.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.2
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• pp.75-80
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• 2013

Cathode is an essential component used in plasma etching process which is to make micro pattern on the silicon wafer. The currently used cathodes produce particles at the high temperature plasma etching process. To overcome this problem, a 'Silicon Only Cathode' was developed. This 'Silicon Only Cathode' requires manufacturing process changes due to the change of shapes, material features, and machining characteristics of work materials. This research investigates the small hole drilling process. The conclusion is that PCD drills with twist angles of $20^{\circ}$ and $25^{\circ}$ were tested for small hole drilling and the experimental results indicate that the drill with $25^{\circ}$ twist angle drill causes less thrust force.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1258-1261
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• 2004

ACSR전력선의 송전용량 증가를 위해 개발된 증용량저이도 송전선인 STACBUAW(Super Thermal-resistant Aluminum alloy Conductors, aluminum-clad Invar-Reinforced)전선은 초내열 Al도체 및 인바강선의 사용으로 비교적 고온에서의 안정적 운전이 가능하다. 그러나 고온 환경에서 장시간 노출된 STACIR/AW전선의 안정적 관리를 위해서는, 열화 된 STACIR/AW 전선의 인장강도, 각 구성소재의 탄성 계수, 비틀림 계수 둥과 같은 기계적 물성이 장기 운전 모의를 위해 설정된 열화온도, 열화시간 등에 대해 종합적으로 평가될 필요가 있다. 또한 크립 등과 같이 고온응력 부하상태에서의 변형거동과 탄성계수 및 선 팽창계수의 온도의존성 등은 전선의 이도관리와 예측을 위해서도 명확히 규명되어야할 중요한 관리 인자이다. 그러나 현재까지는 이들에 대해 수행한 어떠한 연구결과들도 보고 되어 있지 않은 실정이다. 본 연구에서는 STACIR/AW $410mm^2$ 송전선을 장시간 운전의 모의를 위해 가속열화 시키고 가속열화에 따른 STACIR/AW전선 및 그 구성소재의 강도, 비틀림 특성의 변화를 조사하여 장시간 운전에 따른 STACIR/AW전선의 안정성을 평가하여 보고하고자 하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.2
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• pp.137-144
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• 1983

Core walls for tall building is one of the structures to support lateral load. Since most structural elements used for resisting which ate relatively weak against torsion, it is important to investigate tosional effects in the analysis and design of tall buildings. Rutenberg proposed a more refined theory on the torsional analysis of core walls which can be used when the stiffness of lintel beams are small or large. In this paper a more refined method to analysis the torsion of core wall structures with variable cross sections and being subjected to arbitrarilly distributed load was suggested. To reduce complex and a great number of calculations and to enhance the generality and flexibility of application of this method, the discrete method using transfer matrix formulation was used. Then this method can be easily applied to irregular and variational sections, has no necessity to get particular solution for each of loading conditions, and the maximum size of matrix calculated is $4{\times}4$, which makes this approach more appropriate for design office calculations using comuters of any sizes or even desk calculators.

• Composites Research
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• v.17 no.3
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• pp.29-37
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• 2004

The aeroelastic stability analysis of composite bearingless rotors is investigated using a large deflection beam theory in hover. The bearingless rotor configuration consists of a single flexbeam with a wrap-around type torque tube and the pitch links located at the leading edge and trailing edge of the torque tube. The outboard main blade, flexbeam and torque tube are all assumed to be an elastic beam undergoing flap bending, lead-lag bending, elastic twist and axial deflections, which are discretized into beam finite elements. For the analysis of composite bearingless rotors, flexbeam is assumed to be a rectangular section made of laminate. Two-dimensional quasi-steady strip theory is used for aerodynamic computation. The finite element equations of motion for beams are obtained from Hamilton's principle. The p-k method is used to determine aeroelastic stability boundary. Numerical results are presented for selected bearingless rotor configurations based on the lay-up of laminae in the flexbeam and pitch links location. A systematic study is made to identify the importance of the stiffness coupling terms on aeroelastic stability for various fiber orientation and for different configuration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.69-73
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• 2005

ACSR전력선의 송전용량 증가를 위해 개발된 중용량저이도 송전선인 STACIR/AW(Super Thermal-resistant Aluminum alloy Conductors, aluminum-clad Invar-Reinforced)전선은 초내열 Al도체 및 인바강선의 사용으로 비교적 고온에서의 안정적 운전이 가능하다. 그러나 고온 환경에서 장시간 노출된 STAClR/AW전선의 안정적 관리를 위해서는, 열화 된 STACIR/AW 전선의 인장강도, 각 구성소재의 탄성계수, 비틀림 계수 등과 같은 기계적 물성이 장기 운전 모의를 위해 선정된 열화온도, 열화시간 등에 대해 종합적으로 평가될 필요가 있다. 또한 크립 등과 같이 고온응력 부하상태에서의 변형거동과 탄성계수 및 선팽창계수의 온도의존성 등은 전선의 이도관리와 예측을 위해서도 명확히 규명되어야할 중요한 관리 인자이다. 그러나 현재까지는 이들에 대해 수행한 어떠한 연구결과들도 보고 되어 있지 않은 실정이다. 본 연구에서는 STACIR/AW $410mm^2$ 송전선을 장시간 운전의 모의를 위해 가속열화 시키고 가속열화에 따른 STACIR/AW 전선 및 그 구성소재의 강도, 비틀림 특성의 변화를 조사하여 장시간 운전에 따른 STACIR/AW전선의 안정성을 평가하여 보고하고자 하였다.

• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.845-852
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• 2007

An OWC-type Wave Energy Conversion passes through 3 steps energy conversion process. This paper deal with the impulse turbine with staggered blade to improved performance by numerical analysis using commercial CFD code, FLUENT Maximum value of axial airflow velocity during exhalation is higher than that during inhalation This paper deal with special-type of Impulse Turbine so-called "Staggered Blade" for more efficiency to making air flow direct to on pressure side. Also, this paper has proposed special-type turbine with self-pitched blade more efficient.

• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.281-290
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• 2003

A series of connection tests of portal frames which were composed of cold-formed steel studs and rafters was carried out to study the moment-rotation relation, the rotational rigidity, and the yield and the ultimate moment of the connections. The main factors of the tests were the thickness, the shape of the connecting members which were made of mild steel, and the torsional restraints of the test specimens. The test results were compared with those obtained through the non-linear analysis, for verification. The secant stiffness estimated from the experimental moment-rotation curve was proposed for the rotational rigidity of semi-rigid connections, and its validity was verified in the structural frame analysis.

• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.149-159
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• 2009

This paper deals with an analytical study on the aileron reversal characteristics of anisotropic composite aircraft wings modelled as thin-walled beam and having extension-twist structural couplings caused by Circumferentially Uniform Stiffness (CUS) layup scheme. For a study on the aileron reversal of CUS composite wings, it is essential to consider the following effects such as extension-twist structural coupling, wing aspect ratio, and ratio of span-wise and chord-wise length of aileron to wing, initial angle of attack, and sweep angle, etc. The results on the aileron reversal could have a significant role in more efficient designs of thin-walled composite wing aircraft for which this aeroelastic instability is one of the most critical ones.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.386-396
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• 2022

To analyze the influence of variables of roadheaders, the linear cutting testing data of pick cutter were collected from the former literatures. The input factors were set up as uniaxial compressive strength, cutting depth, cutting spacing, attack angle, skew angle, and output factors were determined as specific energy, average cutting force, maximum cutting force, average vertical force, and maximum vertical force. After composing a table of the design of experiment (DOE). The contribution level of each factor was calculated by analysis of variance (ANOVA). As a result, the factors having greatest influence on cutting force and specific energy were uniaxial compressive strength and cutting spacing.