• 지구물리와물리탐사
• /
• 제26권4호
• /
• pp.238-267
• /
• 2023

지구자전과 조석현상에 관하여 19세기 이후 현재까지 알려진 주요 내용들을 소개하였다. 지구자전속도의 영년적/주기적 변화, 세차운동과 장동, 극운동에 관하여 기술하였으며, 또한 지구의 공전/자전 상태와 빙하기도래의 관련설 - Milankovitch 이론에 대하여 돌아보고, 자전과 긴히 연관된 현상으로서 지구조석에 대하여도 기술하였다. 그리고 몇몇 이론적 상세를 부록에 두었다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제7권5호
• /
• pp.998-1013
• /
• 2013

Wireless wearable sensor networks have emerged as a promising technique for human motion tracking due to the flexibility and scalability. In such system several wireless sensor nodes being attached to human limb construct a wearable sensor network, where each sensor node including MEMS sensors (such as 3-axis accelerometer, 3-axis magnetometer and 3-axis gyroscope) monitors the limb orientation and transmits these information to the base station for reconstruction via low-power wireless communication technique. Due to the energy constraint, the high fidelity requirement for real time rendering of human motion and tiny operating system embedded in each sensor node adds more challenges for the system implementation. In this paper, we discuss such challenges and experiences in detail during the implementation of such system with wireless wearable sensor network which includes COTS wireless sensor nodes (Imote 2) and uses TinyOS 1.x in each sensor node. Since our system uses the COTS sensor nodes and popular tiny operating system, it might be helpful for further exploration in such field.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2017년도 추계학술대회
• /
• pp.191-193
• /
• 2017

물리적 객체 기반 및 프레임 단위로 촬영되는 스톱 모션 애니메이션은 전통적인 애니메이션 기술이다. 이는 독립 예술 형태로서 긴 세월의 축적으로 독특한 예술 언어를 형성했다. 애니메이터의 끊임없는 연구와 함께 스톱 모션 애니메이션은 디지털 기술과 적극적으로 결합하여 재료 사용 및 촬영 기술의 발전에 큰 진전을 이루었다. 디지털 기술의 도입은 예술적 표현을 풍부하게 할뿐 아니라 새로운 시대의 지속 가능한 개발을 위한 기반을 마련했다. 본 연구는 3D 프린터 기술이 스톱모션 애니메이션의 제작과정과 산업에 어떠한 영향을 미치는지 탐색하고자 한다.

• Journal of Information Processing Systems
• /
• 제15권6호
• /
• pp.1472-1488
• /
• 2019

Critical elements in the China's Lunar Exploration reside in that the lunar rover travels over the surrounding undetermined environment and it conducts scientific exploration under the ground control via teleoperation system. Such an interplanetary transportation mission teleoperation system belongs to the ground application system in deep space mission, which performs terrain reconstruction, visual positioning, path planning, and rover motion control by receiving telemetry data. It plays a vital role in the whole lunar exploration operation and its so-called trustworthy evidence must be assessed before and during its implementation. Taking ISO standards and China's national military standards as trustworthy evidence source, the net assessment model and net assessment method of teleoperation system are established in this paper. The multi-dimensional net assessment model covering the life cycle of software is defined by extracting the trustworthy evidences from trustworthy evidence source. The qualitative decisions are converted to quantitative weights through the net assessment method (NAM) combined with fuzzy analytic hierarchy process (FAHP) and entropy weight method (EWM) to determine the weight of the evidence elements in the net assessment model. The paper employs the teleoperation system for interplanetary transportation as a case study. The experimental result drawn shows the validity and rationality of net assessment model and method. In the final part of this paper, the untrustworthy elements of the teleoperation system are discovered and an improvement scheme is established upon the "net result". The work completed in this paper has been applied in the development of the teleoperation system of China's Chang'e-3 (CE-3) "Jade Rabbit-1" and Chang'e-4 (CE-4) "Jade Rabbit-2" rover successfully. Besides, it will be implemented in China's Chang'e-5 (CE-5) mission in 2019. What's more, it will be promoted in the Mars exploration mission in 2020. Therefore it is valuable to the development process improvement of aerospace information system.

• 방송공학회논문지
• /
• 제22권3호
• /
• pp.397-400
• /
• 2017

최근 드론, 액션캠 등과 같은 촬영 장비의 활성화로 다양한 전역 움직임을 내포한 영상들이 많이 생성되고 있다. 이때 회전, 확대, 축소 등의 움직임이 발생한 경우, 2D motion vector를 활용하는 기존의 화면 간 예측 방법은 높은 부호화 효율을 기대하기 어렵다. 본 논문에서는 전역 움직임을 homography 참조 픽처를 통해 반영한 비디오 부호화 방법을 제안한다. 제안방법으로, 1) 현재 픽처와 참조 픽처간 전역 움직임 관계를 homography로 파악하여 새로운 참조 픽처를 생성하는 방법, 2) homography 참조 픽처를 화면 간 예측에 활용하는 방법이 있다. 실험은 HEVC 참조 소프트웨어인 HM 14.0에 적용하였고, 실험결과 RA 기준 6.6% 부호화 효율이 증가했다. 특히, 회전 전역 움직임을 지니는 영상을 이용한 실험 결과에서는 기존대비 최대 32.6%의 부호화 효율이 증가하는 결과를 나타내어, 드론과 같이 복잡한 전역 움직임이 자주 나타나는 비디오에서 높은 효율을 보일 수 있을 것으로 기대된다.

• 한국분무공학회지
• /
• 제13권2호
• /
• pp.73-78
• /
• 2008

An experimental study was performed to explore the drop formation and atomization characteristics in electrohydrodynarnic atomization with flow rate, power supply, voltage frequency, and nozzle size. A basic electrohydrodynarnic atomizer equipment was developed for the analysis of spray visualization and tested for the exploration of relationship between several experimental parameters. In results, the varicose wave had been taken place and the small droplets had been generated less than outer diameter of nozzle on the conditions of 25G of nozzle, flow rate of 2 mL/min, and applied frequency of 50kV at AC power over 5kV voltage. The whipping motion had been grown at applied frequency of 400kV and AC power around 2kV voltage

• Structural Engineering and Mechanics
• /
• 제13권5호
• /
• pp.569-589
• /
• 2002

In performing the dynamic analysis, the step size used in a step-by-step integration method might be much smaller than that required by the accuracy consideration in order to capture the rapid chances of dynamic loading or to eliminate the linearization errors. It was first found by Chen and Robinson that these difficulties might be overcome by integrating the equations of motion with respect to time once. A further study of this technique is conducted herein. This include the theoretical evaluation and comparison of the capability to capture the rapid changes of dynamic loading if using the constant average acceleration method and its integral form and the exploration of the superiority of the time integration to reduce the linearization error. In addition, its advantage in the solution of the impact problems or the wave propagation problems is also numerically demonstrated. It seems that this time integration technique can be applicable to all the currently available direct integration methods.

• 한국지구물리탐사학회:학술대회논문집
• /
• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
• /
• pp.81-86
• /
• 2007

Spectral features of the seismic wave propagation from Odaesan Earthquake were evaluated based on the commonly treated random error between the observed data and the prediction values by the stochastic point-source ground-motion spectral model regarding the source, path and site effects. Radiation pattern of the error according to azimuth angle was found to be similar to the theoretical estimate. It was also observed that the spatial distribution of the errors was correlated with the geological map and the Q0 map which are indicatives of seismic boundaries.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제7권2호
• /
• pp.409-425
• /
• 2015

In this paper, we employ a dynamics modeling method for investigating a multi-body dynamics system of semi-submersible autonomous underwater vehicles consisting of a towing vehicle operated near the water surface, a tow cable, and a towfish. The towfish, which is towed by a marine cable for the purposes of exploration or mine hunting, is modeled with a Six-Degree-of-Freedom (6-DOF) equation of motion that reflects its hydrodynamics characteristics. The towing cable, which can experience large displacements and deformations, is modeled using an absolute nodal coordinate formulation. To reflect the hydrodynamic characteristics of the cable during motion, the hydrodynamic force due to added mass and the drag force are imposed. To verify the completeness of the modeling, a few simple numerical simulations were conducted, and the results confirm the physical plausibility of the model.

• 천문학회보
• /
• 제36권1호
• /
• pp.31.1-31.1
• /
• 2011

We present wide-field near-IR imaging polarimetry of 30 Doradus in the Large Magellanic Cloud, using the InfraRed Survey Facility (IRSF). We obtained polarimetry data in J, H, and Ks bands using the JHKs-simultaneous imaging polarimeter SIRPOL. Since many Galactic field stars along the line-of-sight to the Large Magellanic Cloud are contaminated in our data, we developed methods to identify the foreground sources using the proper motion data. We investigated polarimetric properties between the Galactic foreground stars and the stars in the LMC.