• 한국유체기계학회 논문집
• /
• 제15권3호
• /
• pp.51-56
• /
• 2012

This study analyzed the influence of firing biogas on the performance and operation of a gas/steam turbine combined system. A reference gas/steam turbine combined system, designed with biogas fuel(57% volumetric methane) was set up and off-design simulation was made to investigate operating characteristics when a couple of operating schemes to mitigate turbine blade overheating were applied. Performance at base-load operation using each scheme was compared and part load operation using the variable inlet guide vane was analysed. Also, differences in operating characteristics and performance caused by changes in the methane content of biogas and ambient temperature were examined.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1993년도 추계학술대회 논문집
• /
• pp.218-223
• /
• 1993

An UBET(Upper Bound Elemental Technique) program has been developed to analyze forging load, die-cavity filling and effective strain distribution for flashless forging. To analyze the process easily, it is suggested that the deformation is divided into two different parts. Those are axisymmetric part in corner and plane-strain part in lateral. The total power consumption is minimized through combination of two deformation parts by building block method, from which the upper-bound forging load, the flow pattern, the grid pattern, the veocity distribution and the effective strain are determined. To show the merit of flashless forging, the result of flashless and flash forging processes are compared through theory and experiment. Experiments have been carried out with plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agreement with the experimental results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
• /
• pp.23-25
• /
• 1993

This paper presents a design technique of self-organizing fuzzy controller using a learning method of fuzzy inference rule by a gradient method for load frequency control of power system. The membership functions in antecedent part and in consequent part of fuzzy inference rules are tuned by the gradient method. The related simulation results show that the proposed fuzzy controller are more powerful than the conventional ones for reduction of undershoot and deviation of load frequency in steady-state, and for minimization of settling time.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집A
• /
• pp.698-703
• /
• 2001

This paper is concerned with the nonlinear hyperelastic problem fur the incompressible characteristics of the rubber. Tension sensor is a strain gage type load cell element for a fence intrusion detection system and consists of the sensing part and the rubber housing. The analysis includes an elastic analysis and a hyperelastic analysis of a tension sensor for the deformed shape and variation of the maximum strain on the sensing part with respect to the vertical load. Numerical results show that the hyperelastic model is stiffer and less deformed than the elastic model. Comparing with the experimental test data, we know the hyperelastic model is the better approximation than the elastic model.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 춘계학술대회 논문집
• /
• pp.383-389
• /
• 2013

Rotor system is a very important part which produces lift, thrust and control force in helicopter. Component of rotor system must endure various flight load for the required life. In helicopter rotor system, bearingless rotor system is the highest technology rotor system compare with articulated and hingeless rotor system. Baaringless rotor system is not include mechanical flap hinge, lag hinge and pitch bearing. Bearingless rotor component flexbeam which made by composite material has conduct hinge and bearing role instead of mechanical flap hinge, lag hinge and pitch bearing. These characteristics has less part number and lass weight than others. In this paper, conduct safe life analysis of bearingless composite component flexbeam and torque tube applying to utility helicopter load condition.

• 한국산업융합학회 논문집
• /
• 제2권2호
• /
• pp.155-163
• /
• 1999

In this study, single cylinder engines with different tumble ratio were made to find out in-cylinder fluid motion and flame propagation. Tumble ratio derived from the steady state flow rig test. Flame propagation speed was obtained using cylinder head gasket ionization probe and the piston ionization probe. And the combustion pressure in cylinder was measured to analyze the combustion characteristics. In case of high tumble engine, BSFC and BSHC were decreased and BSNOx was increased at part load test. Also BMEP and combustion peak pressure was increased at full load test. Tumble flow motion had an great effects on initial burning period rather than main burning period in part load test.

• Structural Engineering and Mechanics
• /
• 제39권5호
• /
• pp.661-667
• /
• 2011

In the famous equivalent elasticity modulus method proposed by Ernst for the geometrical nonlinear analysis of stay cables, the cable shape was assumed as a parabolic curve, and only a part of the gravity load normal to the chord was taken into account with the other part of gravity load parallel to the chord being ignored. Using the actual catenary curve and considering the entire gravity load of stay cables, the present study has derived the equivalent stiffness method to analyze the sag effect of stay cables in cable-stayed bridges. The derived equivalent stiffness can be degenerated into Ernst's equivalent elasticity modulus method with some approximations. Therefore, the Ernst's method is a special and approximate formulation of the present method. The derived equivalent stiffness provides a theoretical explanation for the famous Ernst's formula.

• 한국화재소방학회논문지
• /
• 제18권4호
• /
• pp.72-77
• /
• 2004

본 연구에서는 외부화염에 의한 비닐코드의 손상에 따른 단락 진행과정, 외형 및 표면 구조,조성 변화 등 단락 특성을 연구하였다. 초고속이미지시스템(HSIS)을 이용하여 단락과정을 분석한 결과, 열적피로에 의해 피복이 소실되면서 전선 도체가 닿아 수회에 걸쳐 단락이 발생하였으며. 실체현미경과 SEM을 이용하여 외형과 표면구조를 분석한 결과, 전원 측 전선은 두 가닥 모두에 용융흔이 형성되었으며 V자형의 흠을 나타냈다. 부하 측 전선의 용융흔은 전원 측 보다 큼을 알 수 있었다. EDX에 의한 조성분석 결과. 전원 측에서는 Cu와 O가 검출되었으며 부하 측에서는 Cu와 O 이외에 피복재료인 Cl과 Ca를 검출할 수 있었다. 이와 같은 실험과 분석결과를 바탕으로 전기화재의 원인을 규명하는데 많은 도움이 될 것으로 기대한다.

• 대한기계학회논문집A
• /
• 제26권10호
• /
• pp.1997-2007
• /
• 2002

Composite air spindles are appropriate for the high-speed and the high-precision machining as small hole drilling of printed circuit board (PCB) or wafer cutting for manufacturing semiconductors because of the low rotational inertia, the high damping ratio and the high fundamental natural frequency of composite shaft. The axial load and stiffness of composite air spindles fur drilling operation are determined by the thrust ben ring composed of the air supply part mounted on the housing and the rotating part mounted on the rotating shaft. At high-speed rotation, the rotating part of the thrust bearing should be designed considering the stresses induced by centrifugal force as well as the axial stiffness and the natural frequency of the rotating shaft to void the shaft from failure due to the centrifugal force and resonant vibration. In this work, the air supply part of the thrust bearing was designed considering the bending stiffness of the bearing and the applied load. The rotating part of the thrust bearing was designed through finite element analysis considering the cutting forces during manufacturing as well as the static and dynamic characteristics under both the axial and con trifugal forces during high-speed rotation.

• 한국구조물진단유지관리공학회 논문집
• /
• 제17권5호
• /
• pp.21-30
• /
• 2013

본 연구는 현재 내측 거더부에 적용하고 있는 LB-Deck를 캔틸레버부까지 확대 적용하기 위하여 Precast Concrete Cantilever Deck를 제안하고, 제안된 PCC-Deck의 구조적인 안전성과 처짐등 거동특성을 평가하였다. PCC-Deck의 구성은 일반부 LB-Deck와 캔틸레버부의 Deck를 주철근과 격자봉을 연장하여 제작하는 방식으로, 기존 LB-Deck을 사용할 경우 발생하는 전도에 대한 문제를 보완하였다. 수치해석 및 실험 결과 최적의 구조로 제안된 D-Type (상부근 16 mm, 격자봉 6 mm, 하부근 12 mm)의 경우 최대하중 28 kN, 최대처짐 27.49 mm로 나타났으며, 자중을 제외한 하중 10kN에서의 시공하중에 대한 내하하중 비율이 2.8로 가장 좋은 결과를 나타냈다. 이러한 결과는 다른 Type의 PCC-Deck 실험체 대비 77.5%의 개선효과가 있는 것으로 평가되었다.