• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2149-2151
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• 2002

In this paper, a novel speed estimation method of an induction motor using neural networks(NNs) is presented. The NN speed estimator is trained online by using the error backpropagation algorithm, and the training starts simultaneously with the induction motor working. The neural network based vector controller has the advantage of robustness against machine parameter variation. The simulation results using Matlab/Simulink verify the useful of the proposed method.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.581-585
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• 2004

The purpose of this study is to suggest a method to support decision making of researchers, when we estimate the safety of the high-speed railway using F-AHP. To apply this method, Korean type of high-speed railway was engaged, and the 8 Stages of accident type and the five criteria were suggested that we must meet. Then, the interview with the researchers working for high-speed railway was used to confirm the alternatives suggested. The employed F-AHP for this study estimate using emotional words based on AHP of Saaty, so it is very good to estimate the high-speed railway safety.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.41-45
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• 1996

In order to realize the high-speed machining, the relative technologies for high speed machining tool and high speed machining are required now, The machining accuracy is influenced on the disturbance by the synchronized working conditions(cutting force, spindle Run-out, thermal deformation etc.) In this paper, the effect of spindle Run-out for the high speed machining is investigated. The results show that the spindle Run-out has a great influence on the machining accuracy in high speed machining.

• 한국기계가공학회지
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• 제11권2호
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• pp.79-84
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• 2012

This study consist of two parts. One is development of a self-propelling vinyl remover which was already reported at the previous paper. This is the second part of the study. For the study, an attached vinyl remover was developed. It was consisted of connecting tractor to bucket, removing bucket from tractor, and the process was the tractor's assistance hydraulics. In the case of an attached vinyl remover, the vinyl was twisted 0.5times per 30~85cm length. The bobbin's diameter was 190mm and it's stable travelling speed was 1m/s. The revolution of the remover wheel was 90rpm to maintain the wheel's linear velocity. As seen at performance test at the field which had 950mm ridge intervals and 10 a area, the average working speed was 1m/s and the turning time was 20seconds. Therefore, the working performance was 24.5min/10a. The efficiency of used vinyl remover was 97% and working conditions were good.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권1호
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• pp.7-14
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• 2017

Due to the recent advances in Phage-Change Memory (PCM) technologies, a new memory hierarchy of computer systems with PCM is expected to appear. In this paper, we present a new page replacement policy that adopts PCM as a high speed swap device. As PCM has limited write endurance, our goal is to minimize the amount of data written to PCM. To do so, we defer the eviction of dirty pages in proportion to their dirtiness. However, excessive preservation of dirty pages in memory may deteriorate the page fault rate, especially when the memory capacity is not enough to accommodate full working-set pages. Thus, our policy monitors the current working-set size of the system, and controls the deferring level of dirty pages not to degrade the system performances. Simulation experiments show that the proposed policy reduces the write traffic to PCM by 160% without performance degradations.

• 한국지열·수열에너지학회논문집
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• 제6권2호
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• pp.23-28
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• 2010

Fluent ver.6.3 is used as CFD(Computational Fluid Dynamics) simulator to predict the performance of snow-melting system by geothermal pipes energy. As the results of this simulation, it is clearly shown that $50^{\circ}C$ of working fluid in to geothermal evaluated as more effect comparing to $45^{\circ}C$ of working fluid. The Surface temperature is come to $5^{\circ}C$ at 1m/s speed and $50^{\circ}C$ temperature of the working fluid.

• Wind and Structures
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• 제29권4호
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• pp.247-270
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• 2019

Wind-resistant design of existing cooling tower structures overlooks the impacts of rainfall. However, rainstorm will influence aerodynamic force on the tower surface directly. Under this circumstance, the structural response of the super-large cooling tower (SLCT) will become more complicated, and then the stability and safety of SLCT will receive significant impact. In this paper, surrounding wind fields of the world highest (210 m) cooling tower in Northwest China underthree typical wind velocities were simulated based on the wind-rain two-way coupling algorithm. Next, wind-rain coupling synchronous iteration calculations were conducted under 9 different wind speed-rainfall intensity combinations by adding the discrete phase model (DPM). On this basis, the influencing laws of different wind speed-rainfall intensity combinations on wind-driving rain, adhesive force of rain drops and rain pressure coefficients were discussed. The acting mechanisms of speed line, turbulence energy strength as well as running speed and trajectory of rain drops on structural surface in the wind-rain coupling field were disclosed. Moreover, the fitting formula of wind-rain coupling equivalent pressure coefficient of the cooling tower was proposed. A systematic contrast analysis on its 3D distribution pattern was carried out. Finally, coupling model of SLCT under different working conditions was constructed by combining the finite element method. Structural response, buckling stability and local stability of SLCT under different wind velocities and wind speed-rainfall intensity combinations were compared and analyzed. Major research conclusions can provide references to determine loads of similar SLCT accurately under extremely complicated working conditions.

• KSBB Journal
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• 제13권5호
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• pp.491-496
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• 1998

The production of fibrinolytic enzyme from Bacillus subtilis BK-17 was studied in the shake flask cultures. The important medium components studied include nitrogen source, carbon source and inorganic salts. The environmental conditions include initial pH, temperature, shaking speed and working volume. Among various N-sources, C-sources and inorganic salts tested, soybean flour, D-glucose and Na2HPO4 gave the best results, and their optimal concentrations were 1.5%, 0.5% and 0.05%, respectively. The optimal pH and temperature were 9.0 and 37$^{\circ}C$. With decreasing working volume in the range of 25∼100ml in the 250ml flask or increasing shaking speed in the range of 100∼300rpm, the enzyme production was greatly enhanced. The enzyme activity under the optimal conditions was about 1400I.U./ml with urokinase as a standard.

• 대한기계학회논문집
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• 제18권6호
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• pp.1572-1581
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• 1994

Heat transfer characteristics in a rotating heat pipe with evaporator of the rotating disc and the condenser of the screwed groove is investigated by numerical method for various dimensionless film thicknesses, Re, C_{p}{\Delta}T/h_{fg}$, rotational speed and working fluids. The temperature difference between evaporator wall and vapor increases a little, but the temperature difference between condenser wall and vapor decreases rapidly as Re increases. As the dimensionless film thickness decreases, the temperature difference of evaporator and condenser decreases. As the rotational speed increases, the temperature difference between evaporator wall and vapor increases but the temperature difference between condenser wall and vapor decreases. The Nusselt number can be shown as a function of dimensionless film thickness and Re, that is $Nu=0.963\cdot(\delta^{-1}(\omega/\vpsilon)^{-1/2}{\cdot}Re^{0.5025})$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.553-556
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• 2003

End-milling have been used in the industrial world because it is very effective to the manufacture of mechanical parts with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. Therefore this study carried to decide the optimum cutting condition for surface roughness and rapid manufacturing time using design of experiment and ANOVA. From the results of experimentation, surface roughness have an effect on cutting direction, spindle speed and depth of cut. And then the optimum condition used Taguchi design is upward cutting in cutting direction, 600rpm in spindle speed, 240mm/min feed rate, 2mm in axial depth of cut and 0.25mm radial depth of cut. By using design of experiment, it is effectively represented shape characteristics of working surface in end-milling.