• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.8-9
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• 2011

본 논문에서는 수상 및 수중운동체의 안정성 및 안정화기법에 관해 고찰한다. 선박이 운동을 하게 되면 부가질량이 변하게 되고 대칭인 시스템행렬이 비대칭이 된다. 비대칭성에 따라 시스템의 안정성해석방법도 달라지는데 예를 들어 가속도 피드백을 통해 비대칭요소를 제거하여 대칭으로 변환시키는 것이 가장 대표적인 해석 및 안정화 기법이다. 시스템 모델자체는 어디까지나 모델이기 때문에 대상시스템을 명확하게 수식으로 표현할 수 없으므로 피드백에 의한 비대칭요소를 소거시키는 방법은 타당하지 못하다. 따라서 본 논문에서는 대칭행렬이 비대칭행렬로 변하는 제약에 구애받지 않는, 보다 일반성을 갖는 안정성해석법을 제안한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.9
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• pp.731-738
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• 2014

The mission of UAV has been expanded from a land to an ocean based on an enhancement of its technologies. Korea Aerospace Research Institute (KARI) also tries to expand the mission of tilt rotor UAV to an ocean, in which the shipboard landing of UAV is required. However the environment of an oceanic operation is severer than that of land due to salty, fogy, and windy condition. The landing point for automatic landing is not fixed due to movement of shipboard in roll, pitch, and heave. It makes the oceanic operation and landing of UAV difficult. In order to conduct an oceanic operation of tilt rotor UAV, this paper presents that the sea wave modeling according to the sea state is conducted and the shipboard landing of tilt rotor UAV under the sea wave is tested and evaluated through the flight simulator for UAV.

• Journal of the KSME
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• v.27 no.6
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• pp.474-477
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• 1987

본 글에서는 동력학에서 좀 어렵게 느껴지는 코리올리 힘(Coriolis force)을 쉽게 알 수 있도록 하기 위하여 몇가지 관련사례를 써 본 것이다. 먼저 뉴우튼의 법칙에 관한 통찰을 설명하고, 코리올리 힘의 공학적 사례를 몇가지 들었다. 그리고, 기초동력학에서 일반적으로 다루지 않는 푸코진자(Foucault's pehdulum)를 쉽게 설명하고, 지상에서 수평운동할 때 편차계산을 쉽게 할 수 있는 방법을 설명하고자 한다.

• Journal of the Daesoon Academy of Sciences
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• v.32
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• pp.237-267
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• 2019

The article considers the problems of envisaging a paradise on earth, with special reference to Jehovah's Witnesses. After an explanation of their relationship to the Christian Protestant tradition, particularly Adventism and American fundamentalism, some key doctrines of the Watch Tower organisation are identified, with particular reference to their belief in a coming earthly paradise. Jehovah's Witnesses are a restorationist movement, seeking a restored paradise on earth, and endeavouring to restore authentic Christianity in what they take to be its original form. Discussion is given to the possibility of physical accommodation on the earth, the position of animals, family life, language, and technology. Finally, brief comparison is made with the expected paradise of the Daesoon Jinrihoe, which is based on a radically different worldview. It is concluded that such differences help to explain why Jehovah's Witnesses have limited success in Korea, as compared with indigenous Korean new religions such as Daesoon Jinrihoe.

• Journal of Astronomy and Space Sciences
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• v.14 no.1
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• pp.109-116
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• 1997

The Mesopause (85km) is the boundary between the Mesosphere and the Thermosphere and is very interesting region because there are active fluid dynamic motions and airglow phenomena due to various chemical reactions. But there have been not many studies due to the difficulties of insitu measurement. However in this study we have obtained the Doppler temperatures and winds through the observing Hydroxyl(OH) emission at 843nm using a ground-based Fabry-Perot interferometer. Due to the 2 years of long term observation, we can confirm the seasonal Mesopause temperature variation, which is the opposite trend against the temperature at the ground level, and reveal annual and biannual variations for meridional and zonal wind respectively. These seasonal variations might be the result of the inter-hemispheric circulation.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.9-15
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• 2004

In this paper, a HILS(Hardware-In-the-Loop-Simulation) System designed for an unmanned airship, which is under development by KARI, is introduced. A HILS system is essential to validate flight control systems on the ground. The HILS system consists of several systems: a virtual ADT(airborne data terminal) system, a virtual payload system, a virtual airship system, and a status display system. Also, a 3-axis motion table and an inertial navigation sensor are included. The reliability of the flight control computer has been validated by HILS tests.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.28-35
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• 2009

This paper derives the equation of coordinated attitude formulation taking into account the orbital dynamics of a target vehicle and the attitude of a tracking satellite in geostationary orbit. The coordinated attitude is always to communicate with the ground station during the target tracking. Because the tracking satellite could perform high angle maneuver, MRP parameters having no singular point are used. Also for the sequential tracking of several target vehicles, the equation automatically making a coordinated attitude is suggested. Coordinated attitude flying and sequential tracking are confirmed through simulations. In short, this paper shows that a satellite could track a target vehicle and communicate with ground station simultaneously using the derived equation of coordinated attitude even though without a accuracy sensor.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.674-682
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• 2009

The purpose of this study was to investigate the effect of aquatic gait training on plantar foot pressure, foot kinesiology and gait speed in right hemiplegic patients. The subject were 20 stroke patients who elapsed from 12 month to 24 month after stroke(aquatic gait training group(n=10), land gait training group(n=10)). This study measured plantar foot pressure, toe out angle, subtalar joint angle, gait speed from data of gate on 2m long measuring apparatus for RS-scan system(RS scan Ltd. German). This experiment performed in twice, before and after the aquatic gait training and land gait training. Collected data were statistically analyzed by SPSS Ver. 12.0 using descriptive statistics, paired t-test. Aquatic gait training group had more variety pressure area on their foot such as T1(Toe 1), HM(Heel medial), and HL(Heel lateral). But motion of subtalar joint flexibility and toe out angle decreased considerably and gate speed also increased. According to the result, aquatic gait training is considered as more effective way in foot stability and normal gait pattern than land gait training.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5180-5188
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• 2015

The purpose of this study was to investigate the effects of a 12-weeks aquarobics on metabolic syndrome risk factors and health fitness in 25 abdominally obese elderly women. As the results, while waist circumference(87.40/82.76cm, p<.01) decreased, HDL-C(41.13/45.42mg/dl, p<.05) increased after the exercise program. Blood pressure and TG, however, decreased with no significance. And while muscle strength increased(17.06/19.08kg, p<.05), the increase in flexibility, muscle endurance, and cardiopulmonary endurance and the decrease in body fat showed some positive effects of the exercise program. In conclusion, we found that the aquarobics improves the aging-induced deterioration in the muscular skeletal function by lowering abdominal obesity and improving metabolic syndrome and physical fitness for health. In addition, the aquarobics can be an effective alternative to an aerobics or a resistance exercise on the ground.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.114-122
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• 2002

The integration of the landing gear system is a complex relationship between the many conflicting parameters of shock absorption, minimum stow area, complexity, weight and cost. Especially ground impact load and dynamic behaviors greatly influence design load of landing gear components as well as load carrying structural attachment. This study investigates ground impact load and dynamic behaviors of the T-50 landing gear system using ADAMS. Taking into account for various operational/environmental conditions, an analysis of shock absorbing characteristics at ground impact is performed with experience derived from a wide range of proprietary designs. Analytical results are presented for discussing the effects of aircraft horizontal and vertical speed, landing attitudes, shock absorbing efficiency. This analysis leads us to the conclusion that the proposed program is shown to be a better quantitative one that apply to a new development and troubleshooting of the landing gear system.