• 전기의세계
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• v.36 no.5
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• pp.316-325
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• 1987

다각 보행 로보트의 세부 개발 분야로는 다음과 같이 세가지로 나눌 수 있다. (1) 기계적 구조 분야-3축 자유도를 갖는 다리의 구조, 에너지 효율을 고려한 다리의 구조, 역학 및 운동학의 분석, 모델화등 (2) 제어분야-다리의 시퀀스 결정, 각 다리의 서보 제어, 균형 및 안정도 유지, 속도제어 (3) 지능 및 센서 분야-장애물 인식, 경로의 판단, 장애물 통과시 다리의 위치 결정 본고에서는 제어분야와 관련하여 걸음새(gait)의 종류 및 표시방법에 대해서 2장에서 언급하고, 3장에서 1각 및 2각 제어 알고리즘을 통해 역학(dynamics)이 고려된 다리의 시퀀스 제어에 관해서 알아보며, 4각 이상의 다각 로보트에 대한 제어문제 및 제어기법에 대하여 4장에서 기술하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1776-1777
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• 2011

인간의 감각 중 후각에 해당하는 가스 센서들에 관한 연구가 현재 상당히 이루어지고 있다. 본 논문에서는 32개의 가스 센서들로 부터 측정된 각각의 값들과 GA를 이용하여, 4개의 센서로 구성되는 8개의 센서그룹을 결정한 후 각각의 그룹에서 나타나는 측정값들의 패턴과 러프집합이론을 이용하여 1차 식별 규칙을 생성하였다. 그 다음 8개 가스 그룹의 식별 패턴을 분석하여 다시 러프집합을 통한 2차 식별 규칙을 생성함으로써 보다 효율적이면서도 판단의 정확성을 높일 수 있는 식별 모델을 설계하는 방법을 다룬다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.10
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• pp.995-999
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• 2015

Inductive sensors are versatile and economical devices that are widely used to measure a wide variety of physical variables, such as displacement, force, and pressure. In this paper, we propose a simple inductive sensor consisting of a thin partial ring and a coil set. The self-inductance of the sensor was estimated using magnetic circuit analysis and validated through finite element analysis (FEA). The natural frequency of the ring was estimated using Castigliano's theorem and the method of equivalent mass. The estimation was validated through experiments and FEA. A prototype sensor with a signal processing circuit is built and applied to noninvasively sense the pressure inside a flexible tube. The obtained sensor outputs show quadratic behavior with respect to the pressure. When fitted to a quadratic equation, the least-square measurement error was less than 2%. The results confirm the feasibility of pressure sensing using the proposed inductive sensor.

• Journal of KIISE
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• v.43 no.12
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• pp.1365-1375
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• 2016

One of the most important capabilities for autonomous service robots working in living environments is to recognize and understand the correct context in dynamically changing environment. To generate high-level context knowledge for decision-making from multiple sensory data streams, many technical problems such as multi-modal sensory data fusion, uncertainty handling, symbolic knowledge grounding, time dependency, dynamics, and time-constrained spatio-temporal reasoning should be solved. Considering these problems, this paper proposes an effective dynamic context management and spatio-temporal reasoning method for intelligent service robots. In order to guarantee efficient context management and reasoning, our algorithm was designed to generate low-level context knowledge reactively for every input sensory or perception data, while postponing high-level context knowledge generation until it was demanded by the decision-making module. When high-level context knowledge is demanded, it is derived through backward spatio-temporal reasoning. In experiments with Turtlebot using Kinect visual sensor, the dynamic context management and spatio-temporal reasoning system based on the proposed method showed high performance.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.3
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• pp.135-141
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• 2008

We propose a new method for recognizing the activities of daily living(ADL) based on the state-dependent motion analysis using 3-axial accelerometers and a glove type RFID reader. Two accelerometers are used for the classification of 5 body states based on the decision tree. Classification of the instrumental activities is performed based on the hand interaction with an object ID using an accelerometer and a RFID reader. Object-dependent hand movements are classified into 5 categories in advance and final decision combines the body state and the instrumental activities. Experiment shows that the suggested hierarchical motion analysis provides accuracy rate of over 90% for all 20 ADLs.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.4
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• pp.323-330
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• 2005

In order to increase reliability and reduce system cost, this paper studies particularly applicable method for sensorless PM BLDCM drive system. The waveform of the motor internal voltages(or back emf) contains a fundamental and higher order frequency harmonics. Therefore the third harmonic component is extracted from the stator phase voltage. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition, and is practically free of noise that can be introduced by the inverter switching, making this a robust sensing method. In addition, a simple starting method and a speed estimation approach are also proposed. Some experimental results are Provided to demonstrate the validity of the proposed control method.

• Smart Media Journal
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• v.5 no.1
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• pp.55-60
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• 2016

Mobility of the sensor networks proposed a new way to the efficient design of sensor networks and improvement of network system performance. Mobility results in a number of functional changes in the MAC protocol and routing protocol. Especially, the mobility of the nodes may occur the increase of the overhead of transmission or disconnection of the link. Therefore, the study of the energy efficient transmission is very important in mobile sensor networks. This paper proposed adaptive transmission mechanism on the distance-based power control. The proposed mechanism was analyzed better than conventional method in the average energy consumption and network life by simulation results.

• Journal of IKEEE
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• v.25 no.4
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• pp.584-590
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• 2021

This paper proposes a removal method of signal interference between ultrasound sensors where ghost signals due to interference are excluded and correct signal is recognized in distance mensurement using ultrasound sensors. The proposed method detects and excludes ghost signals when previous measured distance is compared to current measured distance and the distance difference exceeds a threshold. The threshold is fixed in conventional methods, so ghost signals cannot be correctly excluded when ultrasound sensor or target object move rapidly. On the contrary, to improve accuracy, the threshold is not fixed in the proposed method, and the threshold is adpatively determined based on the relative velocity when ultrasound sensor or target object move. Experiments of distance measurement with ultrasound signal interference are carried out where multiple ultrasound sensors of same type are exploited with maximum interference, and the results show that the proposed method efficiently exclude ghost signals.

• Journal of the Korean GEO-environmental Society
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• v.14 no.3
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• pp.51-60
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• 2013

It is proposed the new method to calculate the absolute altitude and horizontal position of worker in construction field. For this research, we used a pressure sensor, MEMS INS sensor to acquire 3D position of worker. The easiest way to show the result of this research is to use smart phone which equipped various digital sensors in this hardware. So we made two softwares: Data acquisition software in Android smart phone and Data monitoring software in PC. During this research, we encountered several kind of problems which have to be overcame. This paper shows these processes and the results of 3D positioning technologies we suggested newly.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.391-394
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• 2014

In this paper, we introduce a method of determining the absolute position of the rotor for the vector control of Hall sensor type multi-pole BLDC motor using the DSP(TMS320F28335), and implement an algorithm to complement the problems of the conventional method. The switching method of the inverter for providing desired sinusoidal current to each phase of a motor, we adopt Space-Vector pulse width modulation method. In order to increase the speed range, Field-Weakness control method are used. In order to verify the proposed algorithm, we compare the value of Iqe, Ide and phase currents with the values before compensated.