• 한국추진공학회지
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• 제15권3호
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• pp.58-63
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• 2011

본 논문은 유성기어를 적용한 터보펌프의 개념설계에 대하여 기술하였다. 발사체시스템에서는 무게가 가장 중요한 설계인자 중 하나이다. 케로신 혹은 메탄을 연료로 사용하는 터보펌프의 경우 통상 시스템의 간단성 때문에 1축(혹은 동축) 형식이 사용된다. 이 경우 단점은 산화제펌프와 연료펌프의 회전수가 서로 최적이 아닌 상태에서 작동하게 되는 것이다. 각 펌프가 최적 회전수에서 작동하고 또한 증가된 회전속도로 부터 부품의 효율 증대와 무게이득을 최대화하기 위해서는 터보펌프에 유성기어를 적용하는 것이 최선의 방법으로 판단된다. 본 논문에서는 유성기어를 도입한 터보펌프의 개념설계를 수행하여 유성기어의 적용가능성을 제시하였다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제7권4호
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• pp.221-227
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• 2007

This paper introduces an on-line particle-filtering-based framework for failure prognosis in nonlinear, non-Gaussian systems. This framework uses a nonlinear state-space model of the plant(with unknown time-varying parameters) and a particle filtering(PF) algorithm to estimate the probability density function(pdf) of the state in real-time. The state pdf estimate is then used to predict the evolution in time of the fault indicator, obtaining as a result the pdf of the remaining useful life(RUL) for the faulty subsystem. This approach provides information about the precision and accuracy of long-term predictions, RUL expectations, and 95% confidence intervals for the condition under study. Data from a seeded fault test for a UH-60 planetary carrier plate are used to validate the proposed methodology.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.606-621
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• 2004

A dynamic analysis using a hybrid finite element method was performed to characterize the effects of a number of manufacturing errors on bearing forces and critical tooth stress in the elements of a planetary gear system. Some tolerance control guidelines for managing bearing forces and critical stress are deduced from the results. The carrier indexing error for the planet assembly and planet runout error are the most critical factors in reducing the planet bearing force and maximizing load sharing, as well as in reducing the critical stress.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2058-2062
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• 2005

This article describes the useful way to measure the torque and RPM of the geared motor. For this, we have made the planetary geared reduction motor including the torque sensor unit which consists of hall effects sensor and permanent magnet. Our monitoring system displays the sensing values (torque, rpm) and the calculated value (power) and it also has the network capability using the Bluetooth protocol. We will show that our solution is much more inexpensive and simple method to measure torque and rpm than before.

• 천문학회보
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• 제40권1호
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• pp.90.1-90.1
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• 2015

Almost hot-Super Earths ($R_p$~1 to $4R_{earth}$ orbital period < 100 days) are around Sun-like stars. But our solar system does not have hot-Super Earth. Andre et al. 2015 has explained this phenomenon by that Jupiter blocks migration of super earth. We have found a multi-planetary system KOI-94 with exo-Jupiter and hot-Super Earth from NASA exoplanet archive data (http://exoplanetarchive.ipac.caltech.edu). In this study, within multi-planetary systems including hot-Super Earth, we compared those with and without exo-Jupiter using their host star and exoplanet parameters, such as metallicity [Fe/H], $T_{eff}$ and $R_*/R_p$.

• International Journal of Automotive Technology
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• 제8권6호
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• pp.771-780
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• 2007

In recent studies, various types of multi mode electric variable transmissions of hybrid electric vehicles have been proposed. Multi mode electric variable transmission consists of two or more different types of planetary gear hybrid powertrain system(PGHP), which can change its power flow type by means of clutches for improving transmission efficiencies. Generally, the power flows can be classified into three different types such as input split, output split and compound split. In this study, we analyzed power transmission characteristics of the possible six input split systems, and found the suitable system for single or multi mode hybrid powertrain. The input split system used in PRIUS is identified as a best system for single mode, and moreover we identified some suitable systems for dual mode.

• Journal of Astronomy and Space Sciences
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• 제25권3호
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• pp.239-244
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• 2008

Two kinds of important issues on Titius-Bode's relation have been discussed up to now: one is if there is a simple mathematical relation between distances of natural bodies orbiting a central body, and the other is if there is any physical basis for such a relation. These may be tackled by answering a question whether Titius-Bode's relation is valid universally in exo-planetary systems. We have examined whether Titius Bode's relation is also applicable to exo-planetary systems by statistically studying the distribution of the ratio of rotational periods of two planets in an exo-planetary system, 55 Cnc, by comparing it with that derived from Titius-Bode's relation. We find that the distribution of the ratio of rotational periods of randomly chosen two planets in the 55 Cnc system is apparently inconsistent with that derived from Titius-Bode's relation. The probability that two data sets are drawn from the same distribution function is 50%. We also find that the Fourier power spectra show that the distribution of the semi-major axis of planets in the 55 Cnc system seems to be stretched. We conclude by pointing out that large numbers of planets should be examined to more convincingly explain the distribution of the distance of planetary formation regions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.481-483
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• 2004

Many application in robotics, telecommunication, automation systems etc require powerful actuator. The powerful actuator have Speeds up to high speed and high output torque efficiencies. To accomplish a powerful actuator, these powerful motor have to be combined with gearheads of the same outer diameter. So, we have developed BLDC motor and planetary type gearheads as powerful actuator. The BLDC motor have advantages that compact structure, high efficiency, high reliability. The Planetary type gearheads have advantages that same-axle structure, high torque transmission, low noise in comparison with spur gearheads. In this study included BLDC motor and planetary type gearheads design, manufacture. This time study performed for actuator of precision mechanism.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.135-137
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• 2002

Many application in robotics, telecommunication, automation systems etc require powerful actuator. The powerful actuator have Speeds up to high speed and high output torque efficiencies. To accomplish a powerful actuator, these powerful motor have to be combined with gearheads of the same outer diameter. So, we have developed BLDC motor and planetary type gearheads as powerful actuator. The BLDC motor have advantages that compact structure, high efficiency, high reliability. The Planetary type gearheads have advantages that same-axle structure, high torque transmission, low noise in comparison with spur gearheads. In this study included BLDC motor and planetary type gearheads design, manufacture. This time study peformed for actuator of entertainment robot.

• 천문학논총
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• 제30권2호
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• pp.375-379
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• 2015

Planetary nebula in elliptical galaxies pose a problem in dark matter theory. Using data from the Planetary Nebula Spectrograph (PN. S), Romanowsky et al. (2003) reported that less dark matter than expected was found within 5 to 6 effective radii of three elliptical galaxies. We attempt to explain similar observations of elliptical galaxies with MOdified Newtonian Dynamics (MOND). We collect 16 elliptical galaxies with planetary nebulae from the public web data of PN. S. We investigate the dynamical behavior by analyzing the line-of-sight velocity dispersion in the framework of MOND.