• Journal of the Institute of Convergence Signal Processing
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• v.13 no.1
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• pp.44-49
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• 2012

The indirect-contact ECG measurement is a newly developed method for unconstrained and nonconscious measurement in daily Life. This study is the first step to reducing the large background noise appearing in indirect-contact ECG. This study built the thermal noise model of capacitively coupled active electrode which is used in indirect-contact ECG. The results show that the level of thermal noise estimated by the thermal noise model is much the same as that of actual background noise for the capacitively coupled active electrode alone. By applying the actual electrical properties of a sample cotton cloth to the thermal noise model, the theoretical level of thermal noise in the indirect-contact ECG was estimated. The results also show that the level of op-amp's intrinsic noise is so small that it can be negligible in comparison with thermal noise of resistors. The relationship between the level of thermal noise and the resistance of the bias resistor was derived, and it is the base for the further study how to choice the optimal resistance for the bias resistor.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.130-137
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• 1999

In this paper we propose a method of determining the local curvature of a three dimensional convex object using the force and torque information obtained from the active touch of a robot hand. A technique for estimating two dimensional curvature of a convex object are introduced and the way of computing the three dimensional curvature from the two dimensional vurvatures is presented. Also, we develop an experimental system consisting of a finger and verify the effectiveness of the proposed method experimentally.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.91-98
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• 2003

In the field of precision manufacturing demanding high positioning performance, the mechanical friction in positioning device deteriorates the quality of the product and increases the cost of production for positioning devices. Therefore, we propose a contract-free linear actuator using active magnetic bearing. The structure and operating principle of the proposed system are explained, and the magnetic forces are analyzed by magnetic circuit theory to design magnetic bearings and linear actuator. With the derived equation of motion, the stability is identified. Experimental results are presented to show the feasibility.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.201-206
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• 2012

The indirect-contact ECG measurement is a newly developed method for unconstrained and nonconscious measurement in daily life. This study introduced a new method of electrode circuit design developed for reducing the 60Hz power line noise observed at the indirect-contact ECG measurement. By the introduced common-mode-driven shielding, the voltage of the electrical shield surrounding the capacitive coupling electrode is maintained at the same as the common mode voltage. Though the method cannot reduce the level of common mode voltage itself, that reduces effectively the differential mode noise converted from the common mode voltage by the difference of cloth impedance between the two capacitive coupling electrode. The experiment results using the actual indirect-contact ECG showed that the 60Hz power line noise was reduced remarkably though the reduction ratio was smaller than the expected by the theory. Especially, the reduction ratio became large for the large difference of cloth. It is expected that the introduced method is useful for reducing the power line noise under condition of poor electrical grounding.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1757_1758
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• 2009

본 논문에서는 철도차량의 능동조향시스템 연구를 위한 축소 조향대차의 장애물 검지시스템 구축에 대여 연구하였다. 철도차량에서 능동조향이란 곡선부 주행 시 차륜/레일 접촉에 의한 승차감 저하 및 차륜/레일의 마모와 소음을 줄이고, 고속주행을 위한 조향성능 및 주행안정성을 확보하기 위한 휠셋의 제어기술이다. 따라서 논문에서는 조향제어전략 및 제어기법을 연구하기 위한 축소 차량모델(견인대차와 조향대차로 구성)의 개발과정으로서 자동운전을 위한 장애물 검지시스템에 대한 연구를 수행하였으며 주행실험을 통해 그 성능을 검증하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.193-198
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• 1990

전자기 베어링은 기계적 접촉이 없고 전기적 제어가 가능하여 최근 고속 정 밀 회전기에 사용되고 있다. 본 논문에서는 능동 자기베어링을 모형화하고 제어 이득에 따른 계의 안정성 판별 및 응답특성의 변화를 고찰하였다. 이를 토대로 두개의 반경방향 베어링과 회전체를 제작하고 아날로그 제어회로를 구성하여 안정되게 회전체를 부상시킬수 있었으며 이로부터 계의 응답특성 을 구하였다.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.244-247
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• 2001

진동을 감소시키는 방법에는 최적의 설계 변수를 선정하는 수동 제어 방법과 피드백 루프(Feedback loop)를 이용하는 능동제어 방법 두 가지가 있다. 이 중 능동제어에 대한 연구가 최근에 활발히 진행되고 있다. 본 연구에서는 능동제어를 위한 진동시스템의 동적해석과 시스템의 모델링에 대해 연구하고자 한다. 진동체로는 외팔보를 선택하였으며 진동체의 진동을 제어하는 장치로는 제어코일과 베이스코일로 구성된 Push-Pull 타입의 전자석 제어회로를 직접 제작하였고 시스템을 모델링하여 전달함수를 구하고자 한다.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.538-539
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• 2010

자기 베어링 시스템은 축과 베어링간의 자기적 힘을 이용하여 축을 비접촉으로 지지함으로써 고속으로 회전하는 회전체의 마찰손을 저감시킨다. 고속 회전체에 편심(Eccentricity)이 있을 경우 편심 질량으로 인한 원심력이 속도의 제곱에 비례하여 발생하게 되고, 축을 지지하고 있는 베어링에 과도한 진동을 유발하게 된다. 베어링에 전해지는 진동이 커지게 되면 진동 자체도 문제일 뿐 아니라 베어링이 부담해야 하는 힘의 크기가 커지게 되어 자기 베어링 및 이를 구동하는 전력전자 기기의 용량을 증가시켜야 하는 문제가 있다. 본 논문에서는 베어링의 지지력을 능동적으로 제어하는 능동 자기 베어링을 사용하여 축의 편심 질량의 크기 및 편심 위치를 파악하고 회전 관성 중심점으로 축을 회전시킴으로써 회전 진동을 저감하는 방법을 제안하고, 실험 결과로써 제안된 방법의 타당성을 검증한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.121-127
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• 2017

From the perspective of commercializing rotating machines equipped with magnetic bearings, maintaining the error between the mechanical center and the magnetic center within an acceptable level is crucial. The existing method of measuring the center error is to adjust the position references that minimize the current imbalance present in levitation control outputs. However, this method can be applied only after all the components of the system are operational. In this paper, we present a new method of estimating the center error by using only the position sensors and a current source. A force model that relates the position of the rotor with the coil currents is set up. Using this model, the center error is estimated by minimizing the difference between the force angles and the contact angles measured in a pull test. The feasibility of the method is numerically and experimentally validated.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.329-336
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• 2022

Unreadable Khitan scripts of ancient documents written by indian ink on parchment(sheepskin) are visualized by active infrared thermography without contacting and damaging the document which are deteriorated and aged presumably over many years. Sinusoidal infrared thermal wave using Halogen lamp is applied to the surface of the document in order to selectively magnify and record the thermal response of indian ink. The infrared image of the document captured in real time by infrared camera under the active external excitation shows the better sharpness and readability of Khitan characters than the optical image, from which many Khitan letters like ' ' and ' ' sounding as 'd' and 'ri' in English alphabet are detected and deciphered. It is concluded from the experiment that the active infrared thermography can be used as a promising method for digital reconstruction and preservation of ancient documents in the future.