• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.737-741
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• 2003

The wind power system is spotlighted as one of the no-pollution power generation systems. The system uses winds as power source that are rotated the blade and the rotating power from blade generate the electricity power. Gearbox needs to transfer the wind powers that have the high-torque-low-speed characteristics to generator that have the low-torque-high-speed characteristics. Because the wind power system generally locates the remote place like seaside or mountainside and the gearbox installs on the limited and high placed space, the gearbox of the wind power system is required the optimal space design and high reliability. In this paper, the structure of the gearbox is proposed to achieve the optimal space and efficiency by compounding the planetary gear train that has the high power density and parallel type gear train that has the long service life. The design parameters that are affected the service life are studied. The gear ratio and face width are investigated as an affected parameter for design sensitivity of service life.

• Fisheries and Aquatic Sciences
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• 제2권1호
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• pp.52-57
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• 1999

Air-drived rotating biological contactor (RBC) system, which is effective method in filtering performance, was tested for the nitrification capacity in a recirculating system. At ammonia concentrations between 0.029 and 0.528 mg/l, the effect of ammonia loading rate on ammonia removal rate at three different hydraulic loading rates could be defined by the following first­order regression models: Hydraulic loading rate of $14.8 m^3/m^3/day:\;y=39.2\times+3.4 (r^2=0.9137)$, Hydraulic loading rate of $26.5 m^3/m^3/day: y=53.3\times+4.0 (r^2=0.8686)$, Hydraulic loading rate of $37.3 m^3/m^3/day: y=58.4\times+4.2 (r^2=0.7755)$, where, $\times$ is ammonia loading rate (mg/l), y is ammonia removal rate $(g/m^3/day)$, The equations showed the optimal ammonia removal rate at the hydraulic loading rate of $26.5m^3/m^3/day$. Below the ammonia concentration of 2.72 mg/l, first-order regression models between ammonia loading rate and ammonia removal rate at three different rates of speed are defined as follows: Rotational speed of $0.75 rpm: y=28.5\times+4.7 (r^2=0.9143)$, Rotational speed of $1.0 rpm: y=33.6\times+8.4 (r^2=0.9534)$, Rotational speed of $2.0 rpm: y=28.9\times+3.6 (r^2=0.9488)$, where, x is ammonia loading rate (mg/l), y is ammonia removal rate $(g/m^3day)$. The equations show the ammonia removal rate at the rotational speed of 1.0 rpm is significantly higher than that at the rotational speed of either 0.75 rpm or 2.0 rpm (P<0.05).

• Wind and Structures
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• 제31권4호
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• pp.373-380
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• 2020

For large-scale 5MW offshore wind turbines, the discrete equation of fluid domain and the motion equation of structural domain with geometric nonlinearity were built, the three-dimensional modeling of the blade considering fluid-structure interaction (FSI) was achieved by using Unigraphics (UG) and Geometry modules, and the numerical simulation and the analysis of the vibration characteristics for wind turbine structure under rotating effect were carried out based on ANSYS software. The results indicate that the rotating effect has an apparent effect on displacement and Von Mises stress, and the response and the distribution of displacement and Von Mises stress for the blade in direction of wingspan increase nonlinearly with the equal increase of rotational speeds. Compared with the single blade model, the blade vibration period of the whole machine model is much longer. The structural coupling effect reduces the response peak value of the blade displacement and Von Mises stress, and the increase of rotational speed enhances this coupling effect. The maximum displacement difference between two models decreases first and then increases along wingspan direction, the trend is more visible with the equal increase of rotational speed, and the boundary point with zero displacement difference moves towards the blade root. Furthermore, the Von Mises stress difference increases gradually with the increase of rotational speed and decreases nonlinearly from the blade middle to both sides. The results can provide technical reference for the safe operation and optimal design of offshore wind turbines.

• 한국기계가공학회지
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• 제20권7호
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• pp.105-112
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• 2021

Reduction of weld distortions and increase in productivity are some of the major goals of the shipbuilding industry. To address these issues, many researchers have attempted to apply new welding processes. In the shipbuilding industry, steel is the candidate material of choice owing to its good weldability. However, conventional welding techniques are not feasible for avoiding welding problems. Tip-rotating arc welding is one of the high-efficiency welding process that has several advantages, such as high welding speed, high melting rate, low heat input, and less distortion. The present study investigates the influence of the welding variables on the weld characteristics of tip-rotating arc welding. Welding was performed using EH36 as the base metal and SM-70s as the filler metal, which are widely used in shipbuilding. Basic experiments were conducted to understand the effects of the major welding variables, such as welding and tip-rotating speeds. The distortion and mechanical properties of the optimal welding conditions were used to evaluate the tip-rotating arc welding performance. Consequently, the feasibility of the tip-rotating arc welding process for joining steel components was investigated, so that the optimized welding conditions could be applied directly to ship body welding to enhance the quality of the welded joints.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.187-189
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• 1996

In this paper, we have studied several operating characteristics through the analysis of system. First, we have constituted the equivalent circuit to analyze the operating characteristics of rotating type of superconducting power supply and have induced the optimal design parameter. The computer simulation have showed that the pumping current is in proportion to the area of the pole and rotor speed, and is inverse proportion to the magnitude of load. Therefore, to acquire maximum pumping current we must design the power supply system with maximum area of the pole and minimum inductance of the load.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.968-973
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• 2003

Dynamic L/UL system has many merits, but it can develop an undesirable collision during dynamic loading process. In this paper, the dynamics of negative pressure pico slider during the loading process was investigated by numerical simulation. A simplified L/UL model for the suspension system was presented, and a simulation code was built to analyze the motion of the slider. A slider deigns have been simulated at various disk rotating speeds, skew angles of slider. By selection an optimal RPM and pre-skew angle, we can decrease the amount of collision and smoothen the loading process for a given slider-suspension design.

• 정보저장시스템학회논문집
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• 제2권2호
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• pp.144-149
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• 2006

Dynamic L/UL(Load/Unload) system has many merits. but it may happen an undesirable collision during the dynamic loading process. In this paper, the dynamics of negative pressure pico-slider was investigated through numerical simulation during the loading process. A simplified L/UL model for the suspension system has been presented and a simulation code has been developed to analyze the motion of the slider. A slider design has been simulated at various disk rotating speeds, skew angles of slider. We can decrease the possibility of collision and smoothen the loading process for a given slider-suspension design by selection an optimal rpm and pre-skew angle.

• 한국정밀공학회지
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• 제22권6호
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• pp.90-97
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• 2005

Magnetic flywheel system utilizes a magnetic bearing, which is able to support the shaft without mechanical contacts, and also it is able to control rotational vibration. Magnetic flywheel system is composed of position sensors, a digital controller, actuating amplifiers, an electromagnet and a flywheel. This work applies the neuro-fuzzy control algorithm to control the vibration of a magnetic flywheel system. It proposes the design skill of an optimal controller when the system has structured uncertainty and unstructured uncertainty, i.e. it has a difficulty in extracting the exact mathematical model. Inhibitory action of vibration was verified at the specified rotating speed. Unbalance response, a serious problem in rotating machinery, is improved by using a magnetic bearing with neuro-fuzzy algorithm.

• 자원리싸이클링
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• 제6권4호
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• pp.24-30
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• 1997

최근 금속 스크랩의 재활용에 있어서 고품질의 2차지금을 제조하고자 하는 연구가 진행되고 있다. 본 연구에서는 알루미늄 주조품의 기계가공 후 발생하는 알루미늄 Chip을 보다 효율적이고 신속하게 재활용하기 위하여 vortex melting법을 수행하였다. Vortex melting 기술을 chip의 용해공정에 도입하였다. 최적의 vortex 깊이는 수모델 실험을 통하여 결정되었는데, 교반자의 형상, 위치, 회전속도 및 수위 등에 의해 결정된다. Chip의 용해전 상온, 200, 300, $400^{\circ}C$에서 예열하여 vortex의 중앙에 투입하엿다. 따라서, 온도에 따른 회수율을 결정할 수 있었다. 본 실험의 결과로서, 최적의 vortex 깊이는 교반자의 형상, 회전속도에 의해서만 영향을 받으며, 최고의 회수율, 97%는 chip의 예열온도가 $300^{\circ}C$일 경우 얻어졌다.

• Journal of Advanced Marine Engineering and Technology
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• 제31권4호
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• pp.394-400
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• 2007

The properties and weldability of lap joints by PFSW with 1050 Al sheet was investigated according to tool shape. dimension and welding condition. Tensile shear test was carried out for lap jointed specimen, and the hardness in the joint regions was examined. Moreover interfacial joining length, metallograph and failure location of the lap-jointed cross section were discussed. Two tool types were a simple cylindrical type and a notched cylindrical type. Under joining conditions such as plunging depth of 2.2mm. rotating speed of 1600rpm and dwelling time of 3s, the tensile shear strength of lap-jointed specimen by the notched type tool was superior to that by simple cylindrical type tool. The maximum tensile shear load of lap jointed specimen was 5807N. Optimal dimensions of the notched type tool were as follows : diameters of the shoulder and pin were $18{\phi}mm$ and $10{\phi}mm$, and pin length was 2.2mm.