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박정후(Jeong Hoo Park),이광희(Kwang Hee Lee),박구환(Goo Hwan Park),박연수(Youn Su Park) 한국추진공학회 2022 한국추진공학회 학술대회논문집 Vol.2022 No.5
회전익 항공기의 동력 전달 장치는 엔진에서 로터로 동력을 전달하는 역할을 수행하며, 안전과 직결되는 중요한 구성품으로 구성된다. 그 중 유성 기어 박스는 하중 분배 그리고 동력 전달 밀도 등의 장점 때문에 널리 사용되어 왔으며, 최근 eVTOL, tilt rotor, UAVs와 같은 VTOL 적용의 관심이 집중되어 수요가 증가하고 있다. 본 연구에서는 초기 개념 설계 단계에서 회전익 항공기 유성 기어박스 기어 및 베어링 평가를 위한 하중 분배 계수 (Load Sharing Factor) 즉, 안전 계수에 대해 고찰하였다. EC225 사고 조사 보고서 및 베어링 해석 보고서에 명시된 EC225 유성 기어 제원 그리고 수리온 MGB 하우징 모델을 이용하여 EC225 5단 유성 기어 모델링 및 해석을 수행하였으며, 각 유성 기어에 적용되는 하중 분배가 주변 구조물의 강성(Stiffness) 그리고 토크의 크기에 따라 어떤 유의미한 경향을 가지는지 고찰해 보았다. The drivetrain in rotorcraft transmits power from the engines to the rotor system, which consists of a series of safety critical components. The planetary gearbox has been widely used due to its advantage of power density and load sharing, and its demand has been increased due to the recent focus of VTOL applications such as eVTOL, tilt rotor, UAVs. In this study, we discuss Load Sharing Factor (i.e. Safety Factor) for evaluating planetary gearbox gear and bearing of rotorcraft at the initial concept design stage. We choose EC225 5th Stage planetary gear as a case study to demonstrate its influence. The planetary gear stage was modeled, and analysis was performed with reference to the information provided in the EC225 Accident Investigation Report, the Bearing Analysis Report and 3D model of Surion MGB housing. The study shows how the load sharing of each planetary gear changes according to the stiffness of surrounding structures and the magnitude of torque.
Long 전극갭을 가지는 AC PDP의 전기광학적특성에 미치는 돌기전극의 영향
許禎恩(Jeong-Eun Heo),玉政于(Jung-Woo Ok),李敦揆(Don-Kyu Lee),李海準(Hae-June Lee),李?駿(Ho-Jun Lee),朴正后(Chung-Hoo Park) 대한전기학회 2008 전기학회논문지 Vol.57 No.8
In the current PDP technology, one of the most important issues in AC PDP is improvement of luminance and luminous efficacy. To improve luminance and luminous efficacy, new cell structure of PDP containing long discharge path is necessary. However, it causes an increment of firing voltage. In order to decrease firing voltage of AC PDP having long discharge gap, the protrusion electrode is proposed. To drop the firing voltage, the protrusion electrode is inserted into the forward area of the main discharge gap. This paper presents measurements of detailed optical and electrical characteristics of AC PDP with protrusion electrodes. The experimental results show that the proposed structure with gap 80㎛ has lower firing voltage to 27V than that of the conventional long gap structure. Moreover, the ICCD(Intensified Charge Coupled Device) images of the proposed structure show quick discharge generation by 0.07usec and longer continuation by 0.05usec than that of the conventional long gap structure. Therefore, the proposed protrusion electrodes have higher luminance by 12.5% than that of the conventional structure, as having no decrement of Luminous efficacy.
정주영(Joo-Young Jeong),조성용(Sung-Yong Cho),이돈규(Don-Kyu Lee),이해준(Hae-June Lee),이호준(Ho-Jun Lee),박정후(Chung-Hoo Park) 대한전기학회 2009 전기학회논문지 Vol.58 No.8
The discharge electrodes in ac PDP are coated with dielectric layer, and transparent MgO thin films are deposited on the dielectric layer. The main role of the MgO thin films in ac PDP is to protect the dielectric layer from sputtering by ion bombardment in the glow-discharge plasma. An additional important role of the MgO thin film is the high secondary electron emission coefficient which leads the low firing voltage and low cost of the PDP. In this paper, we investigated the relations of the crystal orientation about deposition thickness, deposition rate, temperature of substrate, and distance between the MgO tablet and the substrate. Additionally, we investigated the discharge characteristics of the AC PDP using nano-powder MgO tablet.