• International Journal of Safety
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• 제2권1호
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• pp.17-22
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• 2003

In order to analyze general three dimensional cracks in an infinite body, the symmetric Galerkin boundary element method formulated by Li and Mear is used. A crack is modelled as distribution of displacement discontinuities, and the governing equation is formulated as singularity-reduced integral equations. With the proposed method several example problems for three dimensional cracks in an infinite solid, as well as their growth under fatigue, are solved and the accuracy and efficiency of the method are demonstrated.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1188-1193
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• 1993

For the HST(Hydrostatic Transmission) consisted of a variable displacement axial piston pump and motor, a speed controller with efficiencies considered is proposed. To consider a efficiency in speed control, the displacements of pump and motor which maximize a steady state efficiencies with a various load torque are calculated through computer simulation and these results are reflected to speed controller which has PI control structure with cross over control scheme. It is shown through computer simulation that the proposed controller gives better steady state efficiencies compared with the conventional controller and good transient responses.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.105-110
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• 2003

The hydraulic excavator has been a popular research object for automation because of its multi-workings and economic efficiency. When it works crane tasks, most of disasters happen. The objective of this paper is to design each components and to construct boom, arm, bucket circuit. These models modeled with AMESim show us change of variables and behavior of excavator. Simulation model will be used for simulator of excavator.

• Journal of the Korean Wood Science and Technology
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• 제32권4호
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• pp.66-73
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• 2004

본 연구에서는 국내산 이태리 포플러, 소나무 및 굴참나무를 공시재료로 초산비닐(PVAc), 레조시놀-페놀 공축합 수지(RPR)접착제를 사용하여 핑거공차별(0, 0.15, 0.30, 0.45 mm)로 핑거 접합재를 제작하였고, 종압축 강도성능 시험을 실시하여 다음의 결과를 얻었다.종압축 영률 유효율은 3수종 모두 소재에 비해 현저히 감소하였고, 종압축 강도 유효율은 3수종 모두 평균 90%이상의 높은 유효율을 나타내었다. 특히 소나무재의 경우 모든 조건에서 97% 이상의 높은 유효율을 나타내었다. 최대 변위 유효율은 이태리 포플러재의 경우 소재의 2배, 소나무재와 굴참나무재의 경우 각각 소재의 1.2와 1.3배 정도로 높게 나타났다. 핑거공차에 따른 영향에서는 이태리 포플러재의 경우 핑거공차 0에서 가장 높은 압축강도 유효율을 나타내었고, 소나무재와 굴참나무재의 경우 핑거공차 0.15와 0.30에서 가장 높은 강도 유효율을 나타내는 것이 확인되었다.

• 한국건축시공학회지
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• 제1권1호
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• pp.135-142
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• 2001

This study is for the investigation of form using the aluminum-compound metal frame(Aluminum frame reinforced panel : AFR panel) which is improved in the capacity in the wall-concrete structure in steal of using the existing form which has problems such as, excessive exposure of cement, the loss of labor when it is constructed or disjointed, and it's economical efficiency compared with that of EURO Form. AFR panel passes the KS F 8006 test, and as a result of field test, it's displacement is satisfied with Specification. And using AFR panel is more economical than that of EURO Form because saving labor cost which plays a major part in cost saving in formwork is more effective in retrenching total cost than increment of material cost.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.285-290
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• 2002

Screw in injection molding machine is affected by heat flux, pressure on inside barrel, geometry of screw including flight number, pitch and flight angle. Volumetric efficiency increases as the flight number increases, but it didn't show steady tendency according to helix angle of flight. Heat flux from heating pad and injection pressure play a very important role on the thermal behavior characteristics. The increased number of multi-flight is merits and demerits for a screw efficiency. So, we have to optimize flight number of the screw considering temperature, displacement, distortion and stress of the screw.

• 한국유체기계학회 논문집
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• 제2권4호
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• pp.24-30
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• 1999

An analytical study has been carried out to investigate the effects of the check valve installation on the volumetric and adiabatic efficiencies in a scroll compressor. Both the valve displacement limit and the valve stiffness affected the valve motion, the pressure upstream of the valve, and the pattern of the mass flow through the valve to the discharge plenum. Nonetheless, the presence of the check valve did not cause any noticeable change in the volumetric efficiency. Only a slight increase in the compression work was needed to overcome the pressure increase in front of the valve. The pressure build-up upstream of the valve can be alleviated with the larger limit of the valve lift and a smaller valve stiffness.

• 동력기계공학회지
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• 제4권3호
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• pp.55-61
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• 2000

In this study, a new design of an one-body type of an unbalanced-fixed- displacement type vane pump combined with an induction type electric motor was suggested. By the application of the new design scheme, it was possible to reduce the number of parts of the pump system and to cut down the volume of power package than that of already-used products. The case in this study enabled efficient heat transfer and electricity insulation of hydraulic fluid. Thus oil moves through the inside of the package for cooling and returns to the reservoir. Because of this design, it was difficult to measure the shaft-input torque. Therefore the package overall efficiency in the paper was evaluated with a ratio of hydraulic power and electric power.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1786-1788
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• 2001

A standard source was constructed, and then simulated its light distribution characteristics of the basic arrangements by shape, by angle, and by displacement. And it was constructed a light collecting holder of optical fiber lighting systems using RGB LED. As a result, we obtained the improving light collecting efficiency was improved 6.5 times with compared to existing systems.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.287-290
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• 2006

Orbiter mechanism has been applied to vacuum pump design for small oxygen generator where low vacuum of about 200mmHg is required. Performance of the designed vacuum pump has been numerically investigated: calculated volumetric and adiabatic efficiencies were 69.7% and 83.9%, respectively for leakage clearance of $10{\mu}m$. Total efficiency of the orbiter vacuum pump was 77.5%. At the shaft speed of 1700 rpm suction displacement volume of 6.3cc provided discharge flow at the rate of 2.3 liter/min with power consumption of 10.1Watt. Torque variation of the orbiter pump was only about 20% of that of diaphragm pump.