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소형 추력기의 성능 개선을 위한 액체 추진제 주입기 최적 설계 및 추진제 거동 연구
김기로(Kiro Kim),김수겸(Su-Kyum Kim),변도영(Do-Young Byun),이세민(Se-Min Lee),정강수(Kang-Su Jung),박수형(Soo-Hyung Park),김성균(Sung-Kyun Kim),유명종(Myoung-Jong Yu) 한국항공우주학회 2011 韓國航空宇宙學會誌 Vol.39 No.4
본 연구는 기존의 인젝터와 새로운 형태의 인젝터를 비교분석 함으로써 소형 추력기의 성농을 연구하였다. 기존의 인젝터는 볼록한 표면에 8개의 노즐로 구성되어 액체 추진제를 분사하는 형태로 제작되었다. 우리가 제안한 새로운 형태의 인젝터는 오목한 표면에 4, 5, 6, 8, 9개의 노즐로 구성된 충돌형 인젝터이다. 노즐의 구멍을 통해 분사되는 액체 추진제는 축 방향으로 한 점에서 부딪히게 설계되었으며, 이는 분사되는 액체 추진체의 입자를 더욱 세분화하여 사방으로 일정하게 분무할 수 있도록 하였다. 본 논문에서는 천산유체역학, 입자 유속계 및 고속 카메라를 이용하여 분무 가시화 및 인젝터의 성능을 연구하였다. This work studies the performance of an injector for a monopropellant thruster, comparing a conventional and new injector types. The conventional injector consists of 8 nozzles on a convex surface allowing the jet to be diverged. The new injector, we suggested, is an impinging type with nozzle holes on a concave surface. The fuel streams through the nozzle holes are collide at a point on an axial direction, which allow to atomize the liquid streams and to spray more uniformly along circular direction. The performance of the injectors is investigated by using computational fluid dynamics, particle image velocimetry and high speed camera visualization.
UH-1H 로터 블레이드의 제자리 비행 시 투과면을 이용한 원방 소음 해석
김기로(Ki Ro Kim),박민준(Min Jun Park),박수형(Soo Hyung Park),이덕주(Duck Joo Lee),박남은(Nam Eun Park),임동균(Dong Kyun Im) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.5
본 연구에서는 투과면을 이용하는 음향상사법으로 제자리 비행하는 UH-1H 로터 블레이드 주위의 원방 소음을 예측하였다. 두께 소음과 하중 소음, 그리고 충격파 및 끝단 후류 등에 의해 발생하는 유동 소음을 예측하기 위해 블레이드 표면을 포함하는 투과면을 구성하였다. 3차원 압축성 Euler 방정식 및 Navier-Stokes 방정식을 적용하여 공력 해석을 수행하고 비교하였다. 투과면의 위치에 따라 High Speed Impulsive 소음을 예측 및 검증하였다. 블레이드 끝단에서 발생하는 충격파에 의한 소음원이 지배적인 요소임을 확인하였으며, 충격파를 온전히 포함하도록 투과면을 구성하는 것이 중요함을 보였다. The aerodynamic far-field noise was computed by an acoustic analogy code using the permeable surface for the UH-1H rotor blade in hover. The permeable surface surrounding the blade was constructed to include the thickness noise, the loading noise, and the flow noise generated from the shock waves and the tip vortices. The computation was performed with compressible three-dimensional Euler’s equations and Navier-Stokes equations. The high speed impulsive noise was predicted and validated according to the permeable surface locations. It is confirmed that the noise source caused by shock waves generated on the blade surface is a dominant factor in the far-field noise prediction.
크루즈 선상이벤트 참가동기와 여가제약이 만족과 참가의도에 미치는 영향
김기로(Kim, Ki-Ro),유다종(Yoo, Da-Jong) 한국해양관광학회 2020 해양관광학연구 Vol.13 No.1
The purpose of this study is to understand the basic awareness and needs of cruise tourists cruise events and to help establish marketing strategies that may contribute to increasing domestic cruise tourism demand by understanding the influence of on-board cruise event participation motivation and leisure constraints on satisfaction and participation intention. The frequency analysis, reliability analysis, exploratory factor analysis and regression analysis were conducted for the empirical analysis. The study shows that the novelty, deviance and entertainment have a positive effect on satisfaction, which means that cruise tourists want to actively participate in the on-board events to spend their cruising time more meaningfully and relieve stress. And it also shows that if cruise tourists do not have colleagues, acquaintances, family members on their cruise, or are not used to participating in events with others, it is difficult to feel satisfied psychologically or socially. Moreover, the study informs us that by participating in on-board events, when cruise tourists interact with other people and understand each other and feel refreshed in life in the process, they will consider participating the event again if they have another chance to do so. This study is expected to be basic data for strengthening sales and marketing activities of cruise operators by deriving implications from theoretical and practical aspects through the analysis of the effects of motivation and constraints on satisfaction and participation intention.
다중 투과면을 이용한 UH-1H 로터 블레이드의 제자리 비행 시 원방 소음 해석 연구
김기로(K.R. Kim),박수형(S.H. Park),박민준(M.J. Park),이덕주(D.J. Lee),박남은(N.E. Park),임동균(D.K. Im) 한국전산유체공학회 2017 한국전산유체공학회지 Vol.22 No.3
In this study, aero-acoustics in far-field is computed for the UH-1H rotor blade in hovering flight. A Chimera grid method is applied in this simulation to consider the blade motion and moving effects. Multi-permeable surfaces surrounding a blade are constructed to include the flow noise generated from the shock wave and the tip vortices. A computation is performed with three-dimensional Euler’s equations. An acoustic analogy code using the Kirchhoff approach to Ffowcs Williams and Hawkings equations is applied to efficient the noise prediction caused by volume noise sources in far-field. The high speed impulsive noise on the rotor blade is predicted and validated according to the permeable surface locations. It is confirmed that the noise source caused by the shock waves generated on the blade surface is a dominant factor in the far-field noise prediction.