• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2004년도 춘계학술대회 논문집
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• pp.131-135
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• 2004

강착장치에 의한 지면반력은 착륙과 이륙시 지면과의 상호작용을 나타내며 고도를 감지하여 지면에 접촉하였을 때 지면의 반력을 헬리콥터에 전달해주는 역할을 한다. 비행시뮬레이션에 있어서 강착장치는 비행 중 비행특성에 미치는 영향이 없기 때문에 비행특성 분석용 또는 비행제어용 비행시뮬레이션 프로그램에서는 강착장치를 생략하여 시뮬레이션 하는 경우가 많다. 하지만 훈련의 목적으로 사용하는 경우 착륙과 이륙은 큰 비중을 차지하며 무인기의 함상 착륙과 같은 시뮬레이션에서는 필수적인 요소로 대두되고 있다. 본 논문에서 강착장치는 1자유도의 mass, spring, damper의 간단한 진동시스템을 택하였고, 강착장치의 접촉점인 지면은 고도 0인 평탄한 지면으로 가정하였다. 추후 지면을 6자유도를 가지는 움직이는 평면으로 쉽게 대체할 수 있도록 벡터형식으로 된 모델을 선택하였다.

• 한국지반공학회논문집
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• 제34권6호
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• pp.49-59
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• 2018

차량의 엔진성능에 따라 구동성능이 결정되는 도로주행차량과 달리, 포장되지 않은 지반 위를 주행하는 야지궤도차량의 구동성능은 지반-궤도 접지면에서 발생하는 지반의 전단 및 침하현상에 의해 제한된다. 특히 차량의 중량에 의해 발생하는 정적침하 및 슬립에 의해 유발되는 슬립침하는 지반-궤도 접지면에서 지반저항력을 발현시켜 야지궤도 차량의 구동을 직접적으로 방해하는 요소로 작용한다. 따라서 야지궤도차량의 구동성능을 확보하기 위해서는 정적침하 및 슬립침하를 평가하고 제한할 필요가 있다. 본 연구에서는 야지궤도차량의 중량 및 구동지반의 특성이 슬립침하에 미치는 영향을 종합적으로 평가하기 위하여, 다양한 연직하중 및 지반조건에서 모형궤도시험을 수행하였다. 모형 시험 결과, 모든 시험조건에 대해 슬립율이 증가할수록 슬립침하가 증가했지만, 그 증가량은 점차 감소하는 것으로 나타났다. 또한 궤도시스템에 재하 된 상부 연직하중이 크고 모형지반의 상대밀도가 작을수록 슬립침하가 커지며 이에 따라 지반저항력도 증가하는 것으로 평가되었다. 추가적으로, 평가된 슬립침하를 각 시험조건 별로 산정된 정적침하로 정규화 시킨 뒤 이를 슬립율에 관한 함수로 나타내어 야지궤도차량의 침하량 및 지반저항력 산정 시 활용 가능하도록 하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1244-1250
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• 2008

The site of interest is a residence redevelopment area which has excavation construction with cut-off walls. The site is located over Dong-Mang-Bong tunnel and Seoul No. 6 subway tunnel. This study analyzed numerically the influence of vibrations from No. 6 subway tunnel to the basement of the redeveloped apartment away from the distance about 11m. Kyoung-bu highspeed railway's time history model with linearly reduced maximum acceleration is applied to take into the subway maximum speed of 75km/h. The maximum velocity of vibration for the cross section of the interest was estimated as 0.28cm/sec which satisfied the allowable standard of 0.5cm/sec for apartment and residence of Seoul.

• 한국운동역학회지
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• 제25권2호
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• pp.199-206
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• 2015

Objective : The purpose of this study was to conduct a biomechanical analysis of a one-legged jump in a traditional Korean dance (Wae Bal Ddwigi) according to breathing method. Method : Participants for this study were 10 dancers with experience for at least 10 years in traditional Korean dance. Independent variables for this test were two different types of breathing methods. Dependent variables were ground reaction force and lower extremity kinematic variables. The jumping movement was divided into three separate stages, take off, flight, and landing. The subjects were asked a questionnaire regarding the degree of impact force and stability of landing posture after the experiment. The Kistler Force Plate (9281B, Switzerland) was used to measure ground reaction force. A digital camera was used to look into angles of each joint of the lower part of body. SPSS was used for statistical analysis via the dependent t-test(p<.05). Results : There were significant differences in jumping according to breathing method. The inhalation & exhalation method yielded significantly longer flight times combined with greater ground reaction force. The breath-holding method required more core flexion during landing, increasing movement at the hips and shoulders. Conclusion : Consequently, there was more flexion at the knee to compensate for this movement. As a result, landing time was significantly higher for breath-holding.

• Journal of Astronomy and Space Sciences
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• 제19권3호
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• pp.215-224
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• 2002

This paper describes EGSE design for the small satellite such like KOMPSAT-2 satellite. Recent design trend of small satellite and EGSE is to take short development time and less cost. For this purpose, the design for KOMPSAT-2 satellite and EGSE are not much modified from KOMPSAT-1 heritage. It means that it is able to be accommodated the verified hardware and software modules used in KOMPSAT-1 satellite program if possible. The objective of EGSE is to provide hardware and software for efficient electrical testing of integrated KOMPSAT-2 satellite in three general categories. (1) Simulators for ground testing (e.g. solar-simulation power, earth scenes, horizons and sun sensor). (2) Ground station type satellite data acquisition and processing test sets. (3) Overall control of satellite using hardline datum. In KOMPSAT (KOrea Multi-Purpose SATellite) program, KOMPSAT-2 EGSE was developed to support satellite integration and test activities. The KOMPSAT-2 EGSE was designed in parallel with satellite design. Consequently, the KOMPSAT-2 EGSE was based on the KOMPSAT-1 heritage since the spacecraft design followed the heritage. The KOMPSAT-2 baseline was elaborated by taking advantage of experience from KOMPSAT-1 program. The EGSE of KOMPSAT-2 design concept is generic modular design with preference in part selection with commercial off-the-shelf which were proven from KOMPSAT-1 programs, flexible/user friendly operational environment (graphical interface preferred), minimized new design and self test capability.

• 대한조선학회논문집
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• 제43권1호
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• pp.134-146
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• 2006

This paper presents the primary conceptual design results of twenty-passenger class Wing-In-Ground(WIG) effect craft. As a first step, top level requirements were proposed and principal dimensions were determined. Maximum speed in ground effect condition is 150 km/h with two tons payload including passengers. Total weight is estimated as 8.5 tons with 2 tons of thrust. Hull and airfoil sections were designed and self propulsion tests were performed by radio controlled model. Two planing hull forms with the transom stern were proposed and towing tests were performed. The resistance and running attitude were measured and the feasibility is checked for the prototype hull form of the twenty-passenger class WIG craft. The free running tests show the stable smooth running attitude at designed speed. Also this radio controlled model can take off around 0.15 meter wave height. It can be said that the top level requirement for the twenty passenger class WIG ship is satisfied successfully. The design optimization to increase the transport efficiency and safety will be performed in the near future.

• Current Research on Agriculture and Life Sciences
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• 제1권
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• pp.239-253
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• 1983

This study attempted to introduce Fei-Ranis's agricultural development theory and discuss its problem for the rural development of less developed world. Fei-Ranis systematized the development process of Western European economy on the ground of dualism. They divided the process into 4 stages by the concept of 'mode of operation'. Paticularly, they consider agrarian mercantilism as take-off stage and its development were achieved by the increase of trade margin and labor productivity. Especially, they thought that only agricultural revolution through the diffusion of internal exchange economy and construction of tree-star system can accomplish favorable transition to industrial capitalism. In order to promote this agricultural development, less developed world must abolish short-run agricultural policy and propel 'learning by the contact' strategy through 'tree-star system' and 'parellel development.' In reality, it was problematic that the contemporary less developed world is trying, in the course of a few decades, to imitate Western European experience with development over the last four centuries. But Fei-Ranis ignored qualitative aspects of agricultural development by tree-star system and also it is criticized that they considered agricultural development process of less developed world follows only that of Western European classical process.

• 제어로봇시스템학회논문지
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• 제20권11호
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• pp.1085-1091
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• 2014

This paper presents the guidance and control design for automatic carrier landing of a UAV (Unmanned Aerial Vehicle). Differently from automatic landing on a runway on the ground, the motion of a carrier deck is not fixed and affected by external factors such as ship movement and sea state. For this reason, robust guidance/control law is required for safe shipboard landing by taking the relative geometry between the UAV and the carrier deck into account. In this work, linear quadratic optimal controller and longitudinal/lateral trajectory tracking guidance algorithm are developed based on a linear UAV model. The feasibility of the proposed control scheme and guidance law for the carrier landing are verified via numerical simulations using X-Plane and Matlab/simulink.

• 한국항공운항학회지
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• 제29권3호
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• pp.52-65
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• 2021

A large amount of time and cost is consumed due to congestions caused by an increasing number of cars which results in a lot of emissions. To overcome these problems, a new electric vertical takeoff and landing (eVTOL) aircraft is being considered. Since vertical take off and landing without a separate runway is realized and electricity is used as a power source, it could solve the saturated ground traffic congestions without emissions. In this paper, the initial sizing was performed based on the Nexus 6HX of Belltextron which is a tilt-ducted fan type. In this study, the electric propulsion system that only uses battery was implemented instead of current Nexus 6HX hybrid electric propulsion. Aerodynamic analyses were performed using OpenVSP and XFLR5. Power-to-weight ratio, wing loading, estimated weight were calculated with these analyses.

• 한국항공운항학회지
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• 제32권1호
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• pp.79-90
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• 2024

UAM is emerging due to the deepening population concentration in the metropolitan area and the problem of congested ground transportation in urban areas. Accordingly, along with research on eVTOL aircraft for UAM services, interest in vertiport, the interest in vertiports, the infrastructure that allows eVTOLs to take off and land, is also increasing. However, behind the concentration of population in the metropolitan area, aphenomenon of local extinction is occurring in conjunction with the aging population. AAM, which moves quickly through 3D space, can be an effective SOC facility in times of local extinction crisis. In this paper, we introduce a design plan from the perspective of a complex transper center for a regional hub-level vertiport that can connect with local high-speed rail and utilize local airports in compliance with the vertiport design guidelines issued by FAA(Federal Aviation Administration) and EASA(European union Aviation Safety Agency). We would like to present Vertiport's future operation plan.