• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.79-80
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• 2013

• ETRI Journal
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• 제43권2호
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• pp.221-231
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• 2021

To resolve energy depletion issues in massive Internet of Things sensor networks, we developed a set of distributed energy beamforming methods with one-bit feedback and clustering for multi-node wireless energy transfer, where multiple singleantenna distributed energy transmitters (Txs) transfer their energy to multiple nodes wirelessly. Unlike previous works focusing on distributed information beamforming using a single energy receiver (Rx) node, we developed a distributed energy beamforming method for multiple Rx nodes. Additionally, we propose two clustering methods in which each Tx node chooses a suitable Rx node. Furthermore, we propose a fast distributed beamforming method based on Tx sub-clustering. Through computer simulations, we demonstrate that the proposed distributed beamforming method makes it possible to transfer wireless energy to massive numbers of sensors effectively and rapidly with small implementation complexity. We also analyze the energy harvesting outage probability of the proposed beamforming method, which provides insights into the design of wireless energy transfer networks with distributed beamforming.

• 문화기술의 융합
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• 제10권3호
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• pp.909-914
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• 2024

본 연구에서는 로봇 비전용 영상 인식을 비롯한 다양한 AI 분야에서 널리 활용되는 전이학습에 대한 정량적 평가를 제시하였다. 전이학습을 적용한 연구 결과에 대한 정량적, 정성적 분석은 제시되나, 전이학습 자체에 대해서는 논의되지 않는다. 따라서 본 연구에서는 전이학습 자체에 대한 정량적 평가를 숫자 손글씨 데이터베이스인 MNIST를 기반으로 제안한다. 기준 네트워크를 대상으로 전이학습 동결층의 깊이 및 전이학습 데이터와 사전 학습 데이터의 비율에 따른 정확도 변화를 추적하였다. 이를 통해 첫번째 레이어까지 동결할 때 전이학습 데이터의 비율이 3% 이상일 경우, 90% 이상의 정확도를 안정적으로 유지할 수 있음이 확인되었다. 본 연구의 전이학습 정량 평가 방법은 향후 네트워크 구조와 데이터의 종류에 따라 최적화된 전이학습을 구현하는데 활용 가능하며, 다양한 환경에서 로봇 비전 및 이미지 분석 AI의 활용 범위를 확대할 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.28-32
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• 2007

While various methods for sound source localization have been developed, most of them utilize on the time difference of arrival (TDOA) between microphones or the measured head related transfer functions (HRTF). In case of a real robot implementation, the former has a merit of light computation load to estimate the sound direction but can not consider the effect of platform on TDOAs, while the latter can, because characteristics of robot platform are included in HRTF. However, the latter needs large resources for the HRTF database of a specific robot platform. We propose the compensation method which has the light computation load while the effect of platform on TDOA can be taken into account. The proposed method is used with spherical head related transfer function (SHRTF) on the assumption that robot platform, for example a robot head, installed microphones can be modeled to a sphere. We verify that the proposed method decreases the estimation error caused by the robot platform through the simulation and experiment in real environment.

• 한국시뮬레이션학회논문지
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• 제17권4호
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• pp.249-257
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• 2008

본 논문에서는 로봇 한 대를 중심으로 여러 설비들이 제어되는 Flexible Manufacturing Cell(FMC)에서 로봇의 대기위치 선정과 작업물 선택 의사결정을 위하여 Q-learning 알고리즘을 응용한 방법을 제시하였다. 이를 위해 하나의 로봇과 다수의 설비로 구성된 전형적인 가상의 FMC를 시뮬레이션으로 설계, 제안한 알고리즘을 적용하여 다른 대안과의 비교 분석을 실시하였다. 비교결과 적용된 알고리즘이 로봇가동률을 높여 평균 처리시간, 총 처리량 모두 향상시키는 결과를 가져왔다. 또한, 이 방법은 본 논문에서 제시한 정보뿐 아니라 그 우선순위와 가중치에 따라 다른 정보들을 손쉽게 추가하여 적용할 수 있으므로 FMC의 생산성 향상에도 크게 기여할 것으로 기대된다.

• 제어로봇시스템학회논문지
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• 제7권3호
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• pp.255-262
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• 2001

According to the advancement of web related technologies, many works on robots using these technologies, called web-based robots enables sharing of expensive equipments as well as control of remote robots. But none of the existing methods about web-based robots in-clude robot simulators in their web browser, which transfer appropriate information of a remote place to the local users. In this paper, a web-based robot simulator is proposed and developed to control a remote robot by using the web. The proposed simulator can transfer the 3D information about the remote robot to the local users by using 3D graphics, which has not been previously developed. Also, it sends the camera image of a remote place to the local users so that the users can use this camera image as well as 3D information in order to control the remote robot.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.44-44
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• 2000

Firstly, kinematic model of various type of wheels which includesskidding and skidding friction are presented. Tend, the transfer method of generalized coordinates which is useful to model the parallel mechanisms, can be applied to mobile robot by including such friction terms. Particularly, by appling the modeling method to mobile robot consisting of two conventional wheels and one caster wheel, forword/reverse kinematic modeling could be obtained without using pseudoinverse solutions.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.313-314
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• 2011

• 제어로봇시스템학회논문지
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• 제19권8호
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• pp.688-693
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• 2013

This paper proposes a new method on attitude control of an underwater robot by using five ABTs (Attitude Ballast Tank). A pipe is connected to the bottom of the ABTs and transfers water by a pump, while another pipe is connected to the top of the ABT to transfer air. The buoyancy center of the underwater robot can be changed by means of the water transfer. This way, the attitude of the underwater robot can be maintained and/or controlled as desired. The changes of the center of gravity and the buoyancy central are estimated by a Lagrangian function which is similar to that for an inverted pendulum. The controller in this paper is designed by modeling of the underwater robot and selecting suitable gains of a PD controller which has fast response characteristics. This paper shows the possibility of the attitude control of an underwater robot by changing the center of gravity and the buoyancy center of the robot. Moreover, experimental results verify that the controller is effective in maintaining Roll/Pitch of the underwater robot with very low power consumption.

• 센서학회지
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• 제31권1호
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• pp.12-15
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• 2022

In this study, we studied the effects of transfer gate on the photocurrent characteristics of gate/body-tied (GBT) metal-oxide semiconductor field-effect transistor (MOSFET)-type photodetector. The GBT MOSFET-type photodetector has high sensitivity owing to the amplifying characteristic of the photocurrent generated by light. The transfer gate controls the flow of photocurrent by controlling the barrier to holes, thereby varying the sensitivity of the photodetector. The presented GBT MOSFET-type photodetector using a built-in transfer gate was designed and fabricated via a 0.18-㎛ standard complementary metal-oxide-semiconductor (CMOS) process. Using a laser diode, the photocurrent was measured according to the wavelength of the incident light by adjusting the voltage of the transfer gate. Variable sensitivity of the presented GBT MOSFET-type photodetector was experimentally confirmed by adjusting the transfer gate voltage in the range of 405 nm to 980 nm.