• 천문학회보
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• 제43권1호
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• pp.46.3-47
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• 2018

We present a general N-body exasolar system simulator in anticipation of upcoming searches for exoplanets and even exomoons by next generation telescopes such as James Webb Space Telescope. For habitable zones, traditionally defined by temperature, we here address the essential problem of dynamical stability of planetary orbits. Illustrative examples are presented on P-type orbits in stellar binary systems, that should be fairly common as in Kepler 16b. Specific attention is paid to reduced orbital lifetimes of exoplanets in the habitable zone by the stellar binary, that is propoesed by Maurice van Putten (2017). Especially, we focused on a classic work of complex three-body problem that is well known by Dvorak(1986). We charge his elliptic restricted three-body problem to extend unrestricted three-body problem to look into dynamical motions in view of circumbinary planet, furthermore, we suggest that opposite angular orientation of the planet is relative to the stability of orbits. In here, counter-rotation case is relatively more faster than co-rotation case for being stable. As a result, we find that various initial conditions and thresholds to approach dynamical stability and unstability with unexpectable isolated islands over enormous parameter space. Even, superkeplerian effect of binary is important to habitability of the exoplanet and we can verify that superfaster binary doesn't effect on th planet and increases survivality of planet around the binary.

• 한국생산제조학회지
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• 제25권2호
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• pp.97-104
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• 2016

In this study, the qualitative effects of the positional error of carrier pin holes on the planet load sharing characteristics of the three-point suspension gearbox of wind turbines were investigated experimentally. A 35-kW gearbox comprising two planetary gear stages and a parallel gear stage and size one-fourth of that of a 2-MW three-point suspension gearbox was used as the test gearbox. The strain gauges attached to the ring gear teeth of the input planetary gear stage were used for the purpose of this study. The applied loading conditions were 50%, 75%, and 100% of the rated torque, and the mesh load factor was used as the load sharing index. The experimental results indicated that both the magnitude and direction of the positional error of pin holes had a significant effect on the planet load sharing characteristics of the three-point suspension gearbox. In addition, an increase in the applied torque results in uniform load sharing.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1964_1965
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• 2009

최근 경제성장과 함께 생활수준의 향상으로 인하여 홈 게이트웨이는 디지털 홈 가전기기에 초고속 통신망 접속 기능을 제공하며 각종 기기들을 하나로 네트워크화 하는 중요한 기능을 담당하게 된다. 전력선 통신은 전력선을 매체로 하기 때문에 신규선로의 포설 없이 가전기기 및 정보화 서비스 모뎀들의 네트워크화에 용이할 뿐만 아니라 커버리지 확장에도 뛰어나서 디지털 가전, 원격검침, 전력설비 감시제어, 국가 재난 감시 시스템 등의 기본 통신 방식으로 가장 유력한 기술로써 디지털 가전을 포함한 유비쿼터스 전기설비 네트워크 구성에서 필수적 기술로 채택되고 있기 때문에 지능형 홈 네트워크, 전력IT 부가 서비스, 설비감시 네트워크, 유비쿼터스 네트워크 관련 기술에 대한 파급 효과가 매우 크며, 디지털 가전의 기본 통신 방식으로 가장 유력한 기술로써 디지털 가전 구성에서 필수적 기술로 채택되고 있다. 본 연구에서는 전력선통신모뎀을 이용하여 가전기기의 전력 소비를 감지할 수 있는 센서를 내장한 전력선 통신기반의 전력 감시 모듈을 개발하여 실시간 원격 모니터링을 통해 소비전력 패턴을 작성한다. 그리고 전력감시 모듈에 연결된 가전기기의 소비전력 패턴 분석을 통해 전력소비 이상 유무를 감지할 수 있는 알고리즘을 개발, 탑재하여 이상 유무를 판단하고 전력소비가 급증할 시 자동으로 전력을 차단하여 화재나 누전의 위험을 방지한다. 이에 본 연구는 전력감시 및 이상전력 차단기능을 갖는 저전력 전력선통신 모뎀 개발에 관한 것이다.

• 천문학회보
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• 제36권1호
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• pp.27.1-27.1
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• 2011

We obtained the spectra of 93 Planet host stars and 73 normal field stars in F, G, K type using BOES at BOAO. We measured the equivalent width of Fe and 25 elements lines using the automatic EW measurement program, TAME(Tools for Automatic Measurement of Equivalent-widths) and estimated the elemental abundances by synth and abfind driver of MOOG code. Since the absence of planets in the normal field stars cannot be "completely" proved, this work focused on the chemical abundances and planet properties of planet host stars, which have the massive planets close to the parent star relatively. We carried out an investigation for the difference of abundances between stars with "Hot Jupiter" and normal field stars with no known planets. We examined the chemical composition of 25 elements, such as C, N, O, S, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu by EW measurements, and the S abundances were estimated using synthetic spectrum. We have found that [Mg/Fe] and [Al/Fe] for planet host stars have lower limit comparing with those of comparison stars, and [Ca/Fe] of host star with Neptunian planets is relatively lower than the other host stars with massive planets. We have performed the Kolmogorov-Smirnov test, and examined the ratio of planet host stars to all stars for each bin of [X/H]. As a result, we noted that the O, Si, and Ca abfor undances are strongly related with the presence of planets.

• 대한기계학회논문집A
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• 제36권9호
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• pp.953-960
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• 2012

풍력발전기용 증속기의 유성기어열에서 한단 지지 캐리어에 유연 핀을 적용하여 유성 축과 유연 핀의 변형에 의한 자기 정렬 효과가 증속기 유성기어열의 수명에 미치는 영향에 대한 연구를 수행하였다. 유성기어열의 하중 분배 효과를 분석하기 위하여 오일러 이론과 상용 프로그램을 이용하였다. 풍력발전기용 증속기에 한단 지지 캐리어와 유연 핀이 사용됨에 따라 유성기어의 미스얼라인먼트, 치면 하중분포 계수 및 요구수명이 만족할 만한 성능 향상을 가져왔으며, 특히 요구수명에 있어서 증속기가 요구하는 20년 보증 수명을 만족하는 것으로 확인되었다.

• 천문학회지
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• 제53권6호
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• pp.161-168
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• 2020

We report the discovery of a giant exoplanet in the microlensing event OGLE-2017-BLG-1049, with a planet-host star mass ratio of q = 9.53 ± 0.39 × 10-3 and a caustic crossing feature in Korea Microlensing Telescope Network (KMTNet) observations. The caustic crossing feature yields an angular Einstein radius of θE = 0.52 ± 0.11 mas. However, the microlens parallax is not measured because the time scale of the event, tE ≃ 29 days, is too short. Thus, we perform a Bayesian analysis to estimate physical quantities of the lens system. We find that the lens system has a star with mass Mh = 0.55+0.36-0.29 M⊙ hosting a giant planet with Mp = 5.53+3.62-2.87 MJup, at a distance of DL = 5.67+1.11-1.52 kpc. The projected star-planet separation is a⊥ = 3.92+1.10-1.32 au. This means that the planet is located beyond the snow line of the host. The relative lens-source proper motion is μrel ~ 7 mas yr-1, thus the lens and source will be separated from each other within 10 years. After this, it will be possible to measure the flux of the host star with 30 meter class telescopes and to determine its mass.

• 대한기계학회논문집A
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• 제27권4호
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• pp.491-498
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• 2003

In this paper, dynamic characteristics of an epicyclic gear train considering Coriolis effect have been studied. High speed transmissions such as in an aircraft engines will be strongly influenced by Coriolis effect. Gear meshes were modelled as springs and dampers with periodically varying mechanical constants with time. The loci of planet gear, sun gear. and carrier were analyzed. Maximum values of mesh forces between sun gear and planet gear(S/P) as well as between planet gear and ring gear(P/R) have been simulated as function of rotating speed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2714-2716
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• 2003

대역확산기술의 하나인 Chirp 방식을 이용하여 기존의 전력선 통신모뎀 보다 고속 전송이 가능한 40kbps급 협대역 전력선 통신모뎀을 구현하였다. 본 연구에서 구현한 모뎀은 CEBus 규격을 사용하였으며, $100{\sim}380kHz$의 선형 가변 주파수 신호가 25us 동안 지속한 심볼을 사용하였다. 그리고 구현된 모뎀의 무부하 선로, 각종 부하 및 잡음환경에서의 특성실험 결과, Chirp 방식의 통신기술이 협대역에서 40kbps 이상의 속도를 낼 수 있는 가능성을 확인하였다.

• Journal of Astronomy and Space Sciences
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• 제33권4호
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• pp.257-264
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• 2016

A planet revolving around binary star system is a familiar system. Studies of these systems are important because they provide precise knowledge of planet formation and orbit evolution. In this study, a method to determine the evolution of an exoplanet revolving around a binary star system using different rates of stellar mass loss will be introduced. Using a hierarchical triple body system, in which the outer body can be moved with the center of mass of the inner binary star as a two-body problem, the long period evolution of the exoplanet orbit is determined depending on a Hamiltonian formulation. The model is simulated by numerical integrations of the Hamiltonian equations for the system over a long time. As a conclusion, the behavior of the planet orbital elements is quite affected by the rate of the mass loss from the accompanying binary star.

• ETRI Journal
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• 제43권3호
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• pp.511-523
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• 2021

The World Health Organization provides guidelines for managing the particulate matter (PM) level because a higher PM level represents a threat to human health. To manage the PM level, a procedure for measuring the PM value is first needed. We use a PM sensor that collects the PM level by laser-based light scattering (LLS) method because it is more cost effective than a beta attenuation monitor-based sensor or tapered element oscillating microbalance-based sensor. However, an LLS-based sensor has a higher probability of malfunctioning than the higher cost sensors. In this paper, we regard the overall malfunctioning, including strange value collection or missing collection data as anomalies, and we aim to detect anomalies for the maintenance of PM measuring sensors. We propose a novel architecture for solving the above aim that we call the hypothesis pruning generative adversarial network (HP-GAN). Through comparative experiments, we achieve AUROC and AUPRC values of 0.948 and 0.967, respectively, in the detection of anomalies in LLS-based PM measuring sensors. We conclude that our HP-GAN is a cutting-edge model for anomaly detection.