• 로봇학회논문지
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• 제15권1호
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• pp.39-47
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• 2020

This paper presents a control and operation system for a remotely operated vehicle (ROV). The ROV used in the study was equipped with a manipulator and is being developed for underwater exploration and autonomous underwater working. Precision position and attitude control ability is essential for underwater operation using a manipulator. For propulsion, the ROV is equipped with eight thrusters, the number of those are more than six degrees-of-freedom. Four of them are in charge of surge, sway, and yaw motion, and the other four are responsible for heave, roll, and pitch motion. Therefore, it is more efficient to integrate the management of the thrusters rather than control them individually. In this paper, a thrust allocation method for thruster management is presented, and the design of a feedback controller using sensor data is described. The software for the ROV operation consists of a robot operating system that can efficiently process data between multiple hardware platforms. Through experimental analysis, the validity of the control system performance was verified.

• 한국항공운항학회지
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• 제23권1호
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• pp.49-55
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• 2015

This paper deals with dynamic modeling and controller design of a future Korean lunar module planned to be launched 2020's in Korea. For dynamic modeling of the lunar module, we first assume the lunar module as a rigid body. And we derive equations of motion for the lunar module by considering allocation of main thrusters and reaction thrusters. With the equation of motion, we design the controller based on the quaternion. A Pulse Width Pulse Frequency modulator(PWPFM) is selected for generating on/off signal. Finally, we construct a 2-phase descent mode including initial guidance mode, terminal guidance mode. The MATLAB simulation is performed for evaluating the descent ability and final landing velocity. The dynamic modeling and descent simulation of the lunar module in this paper could be applied for developing the future work of the Korean lunar exploration program.

• 한국생산제조학회지
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• 제25권5호
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• pp.321-328
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• 2016

Cranes are generally used to drop or lift equipment or materials. The present study focuses on equipment used for dropping and lifting the sonar system for undersea exploration. This study deals with a GA-based MATLAB$^{(R)}$ simulation for the design optimization of a new overboarding prototype with a two degree-of-freedom mechanism, including a parallelogram link, which is efficient in sonar system operation and maintenance. First, the strengths and weaknesses of the existing overboarding mechanisms are analyzed. The new mechanism to solve these problems is then suggested. For the proposed mechanism, the GA-based MATLAB$^{(R)}$ simulation technique is applied to the proposed mechanism to optimize the link lengths and the actuator lengths. By doing this, the mechanism cannot interfere in the hull's internal environment. Hence, the work range of motion (ROM) is satisfied, and good torque-angle properties are obtaind. The developed technology will be helpful in calculating the maximized output torque of the actuator for the application in practice using a similar type of the proposed mechanism.

• 감성과학
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• 제16권1호
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• pp.85-94
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• 2013

인체의 동작으로부터 전기 에너지를 수확하려는 압전 에너지 수확에 관한 연구가 최근 활발히 진행되고 있으며, 본 연구에서는 이러한 압전 에너지 수확 소자를 의류에 적용하여 에너지 수확 의류를 설계하였다. 먼저, 동작에너지를 수확하는데 적합한 사지의 인체 부위를 밝히기 위해 3차원 모셥 캡쳐를 실시하였고, 그 결과 엉덩이, 팔꿈치, 무릎이 적합한 부위임이 밝혀졌으며, 이 중, 움직임이 자유로운 팔꿈치와 무릎이 동작에너지 수확 부위로 도출되었다. 압전 에너지 수확 소자의 경우 의류에 적용되기 위해서는 유연하면서도 동작에 민감하게 반응되는 새로운 구조가 필요하였으며, 2개 소자를 적층으로 구성하여 발생하는 전력량을 높이는 새로운 방식이 제안되었다. 의류의 경우 압전 에너지 수확 부위인 팔꿈치와 무릎 부위에서 인체에 잘 밀착되면서 움직임을 제한하지 않는 구조가 요구되었으며, 이에 가장 적합한 무봉제 의류로 제작되었다. 개발된 압전 에너지 수확소자를 부착한 에너지 수확 의류를 시험한 결과 높은 전기에너지 발생 결과를 얻을 수 있었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.537-539
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• 2016

최근 드론, 무인 정찰선 등 무인 기술에 대한 관심이 크게 늘었다. 무인 보트는 사람이 직접 탑승하지 않고 무선 전파로 조종이 가능한 보트를 말한다. 무인 보트는 미 해군에서 처음 개발하여 군사용으로 사용되고 있다. 최근에는 취미용, 농약 살포용, 수상 레저용, 탐사용 등 다양한 방면으로 사용이 확대 되었다. 위의 다양한 무인 보트의 역할 중 탐사용 무인 보트의 경우 사람의 시각에 들어오지 않는 사각지대와 같은 곳을 탐사할 수 없다는 장점이 있다. 본 논문에서는 사각지대와 같은 곳도 탐사가 가능한, 실시간 스트리밍을 지원하는 무인 보트를 Raspberry Pi를 이용하여 구현 했다. 수신기의 신호를 입력받아 송신기로 무인 보트의 조작이 가능하고, 스마트폰의 핫스팟 기능을 이용한 Paspberry Pi와 스마트폰의 네트워크 연결, 이를 통해 Raspberry Pi의 Motion을 이용한 실시간 스트리밍이 가능한 무인 보트이다.

• 한국정밀공학회지
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• 제26권5호
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• pp.41-47
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• 2009

• 한국정밀공학회지
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• 제22권9호
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• pp.99-106
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• 2005

In recent years, vision sensors are widely used to mobile robot for navigation or exploration. The analog signal transmission of visual data being used in this area, however, has some disadvantages including noise weakness in view of the data storage. A large amount of data also makes it difficult to use this method for a mobile robot. In this paper, a digital data compressing technology based on MPEG4 which substitutes for analog technology is proposed to overcome the disadvantages by using DWT(Discreate Wavelet Transform) instead of DCT(Discreate Cosine Transform). The TI Company's DSP chip, TMS320C6711, is used for the image encoder, and the performance of the proposed method is evaluated by PSNR(Peake Signal to Noise Rates), QP(Quantization Parameter) and bitrate.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2005년도 공동학술대회 논문집
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• pp.233-236
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• 2005

천부 탄성파 탐사 기록에서 신호부를 약화시키는 레일리파를 제거하고, 초동 인지가 어려운 S파 신호를 강화하는 방법을 제시하고자 다성분 복소트레이스 분석법에 기초한 분극 필터를 작성하였다. 이 분극필터의 효율성을 시험하기 위해서 단순한 수평 2층 모델 자료를 유한차분법으로 합성하였다. 그 결과 타원운동을 하는 레일리파가 비교적 잘 제거되고 선형운동의 P파와 S파도 효과적으로 분리됨을 볼 수 있었다.

• IEIE Transactions on Smart Processing and Computing
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• 제5권4호
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• pp.235-242
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• 2016

The emerging High-Efficiency Video Coding (HEVC) standard attempts to improve coding efficiency by a factor of two over H.264/Advanced Video Coding (AVC) at the expense of an increase in computational complexity. Mode decision with motion estimation (ME) is still one of the most time-consuming computations in HEVC, as it is with H.264/AVC. Thus, fast mode decisions are not only an important issue to be researched, but also an urgent one. Several schemes for fast mode decisions have been presented in reference software and in other studies. However, the conventional hierarchical mode decision can be useless when block-level parallelism is exploited. This paper proposes operation-level exploration that offers more chances for early termination. An early termination condition is checked between integer and fractional MEs and between the parts of one partition type. The fast decision points of the proposed algorithm do not overlap those in previous works. Thus, the proposed algorithms are easily used with other fast algorithms, and consequently, independent speed-up is possible.

• 한국분무공학회지
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• 제11권3호
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• pp.131-139
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• 2006

An experimental study was performed to investigate the liquid breakup and atomization characteristics in electrohydrodynamic atomization according to the changing of experimental parameters such as nozzle size, fluid flow, and electrical intensity. An original electrohydrodynamic atomizer equipment was designed and manufactured for the analysis of spray visualization and the exploration of relationship between applied power and the behavior of liquid atomization. The image processing technique by using the back-illumination method was applied to visualize the distilled liquid breakup process and to examine the variation of the droplet size distribution. The results show that the spray modes of electrohydrodynamic atomization are closelyconnected by the strength of the electric stresses at the surface of the liquid film and the kinetic energy of the liquid jet leaving the needle tip.