• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.4
• /
• pp.306-314
• /
• 2018

A two-axis gimbal-type X-band antenna for CAS(Compact Advanced Satellite) transmits large amount of image data to ground station regardless of satellite attitude and orbital motion. This antenna mounted on the external surface of the satellite is directly exposed to the extreme space with thermal environment during the orbital operation. Therefore, a proper thermal design is needed to maintain the antenna itself as well as other main components within allowable temperature range. In this study, the thermal design effectiveness of two-axis gimbal X-band antenna was verified through the thermal analysis. In addition, required power and duty cycle of heater were estimated through the thermal analysis under conditions of system level thermal vacuum test and on-orbit thermal environment. The thermal analysis results indicated that all the main components of X-band antenna satisfy the allowable temperature requirement.

• The Journal of Society for e-Business Studies
• /
• v.13 no.1
• /
• pp.1-20
• /
• 2008

Ontologies are expected in various areas as promising tools to improve communication among people and to achieve interoperability among systems. For communications between different business domains, building an ontology through integrating existing ontologies is more efficient way than building the ontology without them. However, integration of ontologies is very struggling work since languages, domains, and structures of ontologies are different from each other. In this paper, we suggest an Ontology Architecture which solves this problem by providing a systematic framework to classify ontologies from three kinds of viewpoints : language, domain range, constructs. The Ontology Architecture consists of 3 axes according to the 3 viewpoints : Ontology Meta Layer axis, Semantic Domain Layer axis, and Ontology Constructs Layer axis. Because 3 axes in Ontology Architecture are designed to improve the syntactic and semantic interoperability among ontologies, the integration of ontologies can be readily achieved.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.6
• /
• pp.1021-1027
• /
• 2006

Torque fluctuation of an engine and angular velocity variation of a propeller shaft are the main excitation sources in the vehicle driveline. This paper presents brief mechanism of these excitation sources. Equivalent models of these systems are construced to simulate the excitation source. The computer simulation was carried out by ARLA Simul v 6.7 and ARLA-Simstat v 2.3. Results of the simulations show the characteristics of torsional excitation source of the driveline. Experimental setups for engine system and propeller shaft system are constructed with component of the vehicle. Torque fluctuation of the flywheel and angular velocity of the propeller shaft were measured from this experimental setups. Experimental results are compared with simulation results. The results from experimental analysis agree with those from theoretical results.

• Journal of Korean Society of societal Security
• /
• v.2 no.3
• /
• pp.47-53
• /
• 2009

This study performed the construction of test bed for the combination of the health monitoring system In Yongjong grand bridge with the safety management network system in order to explore the feasibility of combining the existing monitoring system with the safety management network system. For this purpose, connection program which consists of DAQ sender server program and DAQ receiver server program has been developed. DAQ sender server program installed in the connection server, which is located on the DMZ zone of the existing monitoring system, plays the role of communicating with the monitoring system. On the other hand, DAQ receiver server program installed in the connection server, which is located on the integrated operation center of the safety management network system, plays the part of gathering real time and tim history data of the existing monitoring system and storing them in the integrated operation server through the communication with the DAQ sender. Test bed demonstrated the feasibility of combining the existing monitoring system with the safety management network system.

• Korean Journal of Optics and Photonics
• /
• v.20 no.6
• /
• pp.328-333
• /
• 2009

We proposed a three-dimensional holographic display technique without twin image noise by converting a complex hologram to an off-axis hologram. To implement the proposed technique we record the complex hologram of a three dimensional object that is composed of two slides located with different depth locations. We added spatial carrier to the complex hologram and after that, extract the real part of the spatial-carrier-added hologram. This converts the complex hologram to an off-axis hologram. We also reconstruct the off-axis hologram using a spatial light modulator for three dimensional display.

• The Journal of the Acoustical Society of Korea
• /
• v.24 no.5
• /
• pp.262-270
• /
• 2005

In this paper, a new temporal decomposition method is proposed. where not oniy distortion but also entropy are involved in segmentation. The interpolation functions and the target feature vectors are determined by a dynamic Programing technique. where both distortion and entropy are simultaneously minimized. The interpolation functions are built by using a training speech corpus. An iterative method. where segmentation and estimation are iteratively performed. finds the locally optimum Points in the sense of minimizing both distortion and entropy. Simulation results -3how that in terms of both distortion and entropy. the Proposed temporal decomposition method Produced superior results to the conventional split vector-quantization method which is widely employed in the current speech coding methods. According to the results from the subjective listening test, the Proposed method reveals superior Performance in terms of qualify. comparing to the Previous vector quantization method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.6
• /
• pp.771-780
• /
• 2010

This paper describes the design process of a six-component force/torque (F/T) sensor. The new six-component F/T sensor having leaf spring ends has been developed using a cross beam structure as the basic sensing element. Fundamental strain analysis of both ends fixed beam having a leaf spring structure is performed by finite element analysis. In order to obtain similar output sensing strains from the six component loads and minimize coupling strains, the optimal location of strain gages is determined and the strain gages are connected so that the bridge circuits with four strain gages would be balanced. Using leaf spring ends instead of rigid fixed ends, remarkable increment in output sensing strain can be achieved for two component forces. Several modifications in design result in a similar sensing strain of approximately $400\;{\mu}m/m$ for the six-component forces and moments, and a reduced coupling strain of $0\;{\mu}m/m$ between the forces and moments.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.255-258
• /
• 1998

이동로봇이 움직이는 물체를 추적하는 기능을 갖도록 하기 위해서는 움직이는 물체의 존재를 판단하고 위치 및 속도벡터를 측정해야 한다. 본 논문은 단시간에 이동 물체의 위치와 속도벡터 추정하여 실시간 추적이 가능하도록 하기 위해 초음파센서를 이용한 가상의 초음파영상 해석방법을 제안한다. 초음파 영상은 초음파센서의 매회 측정값을 누적하여 구성하며 거리축과 시간축을 갖는 2차원 영상으로 표현된다. 영상에서 측정된 물체가 만드는 선분의 기울기에 따라 이동하는 물체와 정지한 물체를 분리하고 속도를 측정한다. 제안된 방법은 시뮬레이션을 통해 타당성을 입증하였다.

• Proceedings of the KIEE Conference
• /
• 2001.11c
• /
• pp.331-333
• /
• 2001

원통 모양의 선형 유도 전동기를 구성하고 코일의 밖에 위치한 코일에 전류가 유도되며 이때 코일의 축방향과 이에 수직인 방향으로 힘이 유도되며, 이때 힘의 특성이 유도 전동기의 특성을 지님을 밝혀 내었다. 이 힘은 두 코일의 축이 어긋나서 생기는 힘과, 드라이브 코일의 open slit의 정도에 따라 다른 것을 밝혔다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2018.05a
• /
• pp.88-89
• /
• 2018

최근 VR 환경은 모바일학습, 스마트 공장을 포한함 다양한 분야에서 활용되고 있으나 이를 위한 HMD의 가격은 독립된 적용 플랫폼을 사용하고 있으며 고가의 HMD을 요구하고 있다. 본 논문에서는 무선으로 3D 콘텐츠를 제공받는 저가의 모바일 VR HMD 구성 및 이를 활용한 VR 모바일 플랫폼을 설계한다. 이를 위해 사용자의 움직임을 검출하기 위해 6축 센서를 사용하여 VR 콘텐츠 서버에서 렌더링된 3D 이미지 랜더링를 처리하도록 개발하였다.