• 한국소음진동공학회논문집
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• 제17권6호
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• pp.539-546
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• 2007

Information storage devices using disks have a disk vibration at the frequency which is equivalent to the disk rotational speed. They also have a track vibration due to the disk eccentricity at the same frequency. In near field recording systems, the former affects the air-gap servo and the latter affects the tracking servo. In this paper, we introduce a novel control algorithm based on the internal model principle to both servos. A controller block designed by the principle is connected to the base lead-lag type compensator in parallel in order to cancel the repeatable run-out due to the disk vibration or eccentricity. Simulation and practical application of the algorithm on a near field recording system show good servo performance.

• 천문학회보
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• 제42권2호
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• pp.43.4-44
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• 2017

Bar fractions depend on the properties of host galaxies. However, the observational studies did not provide consistent tendency. We investigated the bar fractions and their dependence on properties of host galaxies using three bar classifications: visual inspection, ellipse fitting method and Fourier analysis from a volume-limited sample of 1,698 disk galaxies brighter than Mr=-15.2 within z = 0.01 from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). We found two causes to make the discrepancy in previous studies. One is caused by the difficulty in automatically identifying bars for bulge-dominated galaxies. In particular, ellipse fitting methods could miss early-type barred galaxies when a large bulge weakens the transition between a bar and disk. The other is caused by the difference in the correlation between the bar types and host morphology for strong bars and weak bars. Strong bars are preponderant in early-type spirals which are red, bulge-dominated and highly concentrated, whereas weak bars are frequent in late-type spirals which are blue, disk-dominate and less-concentrated. Therefore, how much weak bars they contain affects the trend of bar fraction on host galaxy properties. We also discuss the effect of host properties on the formation, evolution, and destruction of bars.

• 한국잡초학회지
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• 제30권4호
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• pp.380-389
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• 2010

본 연구는 유전자총기법에 의해 생산된 형질전환 고구마를 사용하여 glufosinate-ammonium에 대한 저항성 유무를 빠르고, 경제적이며, 신뢰할 수 있는 간이분석법을 찾고자 수행되었다. 저항성 진단법은 whole-plant 진단법, one leaf 진단법 및 leaf disk 진단법을 사용하였고, 이들 진단법에 의해 glufosinateammonium을 처리하고 잎의 피해율과 암모늄 축적량을 조사하였다. Leaf disk 진단법에서 glufosinateammonium 처리 후 형질전환 라인 7171의 잎에 대한 약해는 wild type에 비해 1.9배 낮았다. One leaf 진단법과 whole plant 진단법의 경우 glufosinateammonium 처리 후 7171의 잎에 대한 약해는 wild type에 비해 각각 59배와 92배 적었다. Leaf disk, one leaf와 whole plant 진단법에서 0.5-5mM glufosinateammonium 처리 후 암모늄 축적은 wild type이 7171에 비해 각각 2-20, 4-43 및 6-115배 더 많이 축적되었다. 이들 3가지 방법 모두 형질전환 고구마에 대한 glufosinate-ammonium 저항성 유무를 판단하는데 가능한 방법이나 one leaf 진단법이 가장 간편하면서 빠른 진단방법이었다. 그러나 이 방법은 엽령별 내성차이가 존재할 수 있어 고구마 엽이 10개 전개되었을 때 1, 3, 5, 7, 9엽을 각각 채취하여 3mM glufosinateammonium을 처리시 잎의 피해율과 암모늄 축적을 엽령별로 조사한 결과 유의적인 차이를 보이지 않았다. 따라서 분석에 소요되는 기간, 시료량, 정확성 등을 고려할 때 형질전환 고구마의 저항성을 판별하는데 one leaf 진단법이 가장 적합한 것으로 판명 되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.555-560
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• 2000

An experimental study on pumping characteristics of various turbo-type drag pumps is purformed. The inlet pressures are measured for various outlet pressures of the test pump. The maximum compression ratios for nitrogen are 100,000(Disk-type drag pump+ turbo molecular pump), 10000(Helical-type drag pump+turbo molecular pump), 850 (Helical-type drag pump), 100(disk-type drag pump).

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.634-639
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• 2003

It has been studied the flow near a rotating disk with surface topography. The system Ekman number is assumed very small, i.e., $E[{\equiv}\frac{\nu}{{\Omega}^{\ast}L^{\ast2}}]<<1$ in which $L^{\ast}$ denotes a disk radius, ${\nu}$ kinematic viscosity of the fluid and ${\Omega}^{\ast}$ angular velocity of the basic state. Disk surface has a sinusoidal topographic variation along radial coordinate, i.e., $z={\delta}cos(2{\pi}{\omega}r)$, where ${\delta}$ and ${\omega}$ are, respectively, nondimensional amplitude and wave number of the disk surface. Analytic solutions, being useful over the parametric ranges of ${\delta}{\sim}O$( $E^{1/2}$ ) and ${\omega}{\leq}O$ ( $E^{1/2}$ ), are secured in a series-function form of Fourier-Bessel type. An asymptotic behavior, when $E{\rightarrow}0$, is clarified as : for a disk with surface roughness, in contrast to the case of a flat disk, the azimuthal velocity increases in magnitude, together with the thickening boundary layer. The radial velocity, however, decreases in magnitude as the amplitude of surface waviness increases. Consequently, the overall Ekman pumping at the edge of the boundary layer remains unchanged, maintaining the constant value equal to that of the flat disk.

• International journal of advanced smart convergence
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• 제11권3호
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• pp.206-214
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• 2022

Automobile manufacturers in each country are spurring the development of electric vehicles that use electric energy, an eco-friendly energy, as a futuristic vehicle. Electric vehicles have the advantage of no harmful gas or environmental pollution and low noise. Unlike automobiles using existing internal combustion engines using fossil fuels, electric vehicles use the electricity of batteries to cause rotational motion of motors. In the electric vehicle driven by the motor, it is indispensable to develop a controller for controlling the motor. One of the areas where automobile manufacturers are concentrating is the development of small electric vehicles as a personal transportation means. Small electric vehicles such as electric motorcycles, one-seat electric vehicles and two-seat electric vehicles are expanding the market as a means of operating throughout the city. In the domestic road conditions with many hills, it is effective to have a separate transmission system for small electric vehicles to drive smoothly. In this study, we propose a new type of continuously variable transmission(CVT) system to ensure that small electric vehicles can be driven smoothly in hilly domestic terrain. The proposed CVT system is equipped with a basic disk and a rotational disk in the driving pulley and the driven pulley, respectively, and is applied with a sloping spline to rotate the rotational disk. To commercialize the proposed CVT system, an experimental device was developed to examine the power transmission efficiency and the configuration of the CVT system was proposed.

• 조명전기설비학회논문지
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• 제30권1호
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• pp.72-78
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• 2016

In terms of power components which use environmentally-friendly dry air that can substitute SF6, there have been studies on the electrical properties of the solid insulation "spacer" for the purpose of securing dielectric strength as they become smaller. This study laminated solid insulation to keep the creeping distance the same in the dry air and investigated vertical surface discharge characteristics by shape. The three sheets of disk-type solid insulation(Bakelite) were laminated in a manner to keep the creeping distance the same. The lamination was categorized as follows: "Type A" in which the insulations with the same disk diameter were laminated; "Type B" in which the insulations whose middle disk diameter was large were laminated; and "Type C" in which the ones whose middle disk diameter was small were laminated. For a vertical surface discharge experiment, dry air was injected into the test chamber depending on the shape of the laminated solid insulation, and chamber pressure was adjusted in a range of 0.1-0.6MPa. As volume decreased, surface discharging voltage by unit volume increased. This was because of dielectric polarization according to the structural characteristics of the shape of lamination. The highest surface discharging voltage was found in "Type C."

• 대한수학회지
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• 제43권2호
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• pp.425-443
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• 2006

The aim of this paper is to obtain several results in approximation by Jackson-type generalizations of complex Picard, Poisson-Cauchy and Gauss-Weierstrass singular integrals in terms of higher order moduli of smoothness. In addition, these generalized integrals preserve some sufficient conditions for starlikeness and univalence of analytic functions. Also approximation results for vector-valued functions defined on the unit disk are given.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.285-291
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• 1998

A hydraulic pin-on-disk type tribotester was developed and it's performance was investigated experimentally. The estimate of the performance was accomplished by comparing those of the pneumatic and the dead-weight loading method. The reliability to the performance was conformed. By hydraulic loading method more accra'ate friction coefficient could be got.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 하계학술발표대회
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• pp.80-80
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• 2005