• 제어로봇시스템학회논문지
• /
• 제9권10호
• /
• pp.755-767
• /
• 2003

This paper proposes a robust fault-tolerant control framework for robot manipulators to maintain the required performance and achieve task completion in the presence of both partial joint failures and complete joint failures and uncertainties. In the case of a complete joint failure or free-swinging joint failure causing the complete loss of torque on a joint, a fully-actuated robot manipulator can be viewed as an underactuated robot manipulator. To detect and identify a complete actuator failure, an on-line fault detection operation is also presented. The proposed fault-tolerant control system contains a robust adaptive controller overcoming partial joint failures based on robust adaptive control methodology, an on-line fault detector detecting and identifying complete joint failures, and a robust adaptive controller overcoming partial and complete joint failures, and so eventually it can face and overcome joint failures and uncertainties. Numerical simulations are conducted to validate the proposed robust fault-tolerant control scheme.

• 로봇학회논문지
• /
• 제10권4호
• /
• pp.223-229
• /
• 2015

This paper proposes a novel method for detection of hand raising poses from images acquired from a single camera attached to a mobile robot that navigates unknown dynamic environments. Due to unconstrained illumination, a high level of variance in human appearances and unpredictable backgrounds, detecting hand raising gestures from an image acquired from a camera attached to a mobile robot is very challenging. The proposed method first detects faces to determine the region of interest (ROI), and in this ROI, we detect hands by using a HOG-based hand detector. By using the color distribution of the face region, we evaluate each candidate in the detected hand region. To deal with cases of failure in face detection, we also use a HOG-based hand raising pose detector. Unlike other hand raising pose detector systems, we evaluate our algorithm with images acquired from the camera and images obtained from the Internet that contain unknown backgrounds and unconstrained illumination. The level of variance in hand raising poses in these images is very high. Our experiment results show that the proposed method robustly detects hand raising poses in complex backgrounds and unknown lighting conditions.

• 대한안전경영과학회지
• /
• 제13권1호
• /
• pp.41-49
• /
• 2011

The automatic fire detection system is an important facility installed with focusing on minimizing the damage from a fire. This paper presents in the followings as the methods to reduce the false alarm of the automatic fire detection system; first, to prepare for legal standard so that revised legal standard can be applied to the fire fighting property prior to revision; second, to introduce the performance based fire detection protection design in the law based fire protection design; third, to maintain the wiring of worn-out detector; forth, to introduce an evaluation system to the education for the fire warden; fifth, to extend the standard of MTBF(meantime between failure) of the detector; sixth, to extend of installing the analog type detector; seventh, to improve the structure of reset switch.

• 융합신호처리학회논문지
• /
• 제11권4호
• /
• pp.298-302
• /
• 2010

체외 순환 보조 장치는 호흡부전 및 심부전 등에 사용하는 장치이며 세계적으로 많은 연구 개발과 임상에의 사용이 계속되고 있다. 이 장치들을 사용할 때 주의해야할 사항중 하나는 공기 색전증이다. 공기 색전증은 정맥혈내로 공기가 들어갈 수 있는 여러 가지 수술 과정 및 진단 과정의 합병증으로 일어날 수 있으며, 수술부위가 심장보다 위치, 수술 과정 중 체강, 체외 순환 보조 장치를 사용할 때 공기의 유입이 생길 수 있다. 이러한 문제를 해결하기위해 비유전율 상수의 변화를 이용한 공기방울 감지 장치를 개발했다. 모의순환 장치에서 실험해본 결과 튜브 안의 공기 양에 따라 신호의 차를 분명하게 보여주어 공기방울을 감지할 수 있었다.

• Journal of Multimedia Information System
• /
• 제4권4호
• /
• pp.285-288
• /
• 2017

In this paper, we propose a vision-based object detection and tracking system using online learning. The proposed system adopts a feature point-based method for tracking a series of inter-frame movement of a newly detected object, to estimate rapidly and toughness. At the same time, it trains the detector for the object being tracked online. Temporarily using the result of the failure detector to the object, it initializes the tracker back tracks to enable the robust tracking. In particular, it reduced the processing time by improving the method of updating the appearance models of the objects to increase the tracking performance of the system. Using a data set obtained in a variety of settings, we evaluate the performance of the proposed system in terms of processing time.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 춘계학술대회 논문집
• /
• pp.1650-1655
• /
• 2007

A lights-out detector, which helps the person in charge of maintenance make a quick judgment in the event of a failure of LED-type traffic lights, was explored/developed and installed/ tested, at Seoul Metro, after they developed a patented pilot product in 2005; and, a product improvement test was conducted to ensure reasonable maintenance of signaling facilities. Having better compatibility with existing circuit in use and displaying stable load current, the device makes the maintenance of lights-out detection and alert easier.

• 대한의생명과학회지
• /
• 제3권1호
• /
• pp.29-35
• /
• 1997

본 연구에서는 한국인 만성신부전증 환자에서 심혈관계 질환의 조기진단을 위한 생화학적 표지 자로서 homocysteine의 임상적 유용성을 검토하기 위하여, 만성신부전증 환자와 건강인에서 HPLC/FLD (high performance liquid chromatography/fluorescence detector)를 이 용하여 혈장 homocysteine 농도를 측정하고 그 결과를 비교하였다. 본 실험방법의 회수율은 98.6$\pm$5.8%를 나타내었으며, 0.2 nmol/L 보다 낮은 농도까지 측정이 가능하였고, 2~50 nmol/ml까지 직선성이 성립하였다 (correlation coefficient =0.9997). 한국인 중 건강한 정상인 (20명)과 만성신부전증 환자 (90명)에서 혈장 homocysteine은 각각 6.81$\pm$1.54 nmol/ml과 27.28$\pm$14.94 nmol/ml이었으며 , 환자군에서는 정상인군에 비하여 약 4배정도 높은 수치를 나타내었다 (p<0.05).본 실험의 결과로 볼 때 HPLC/FLD를 이용한 homocysteine 측정은 예민도와 재현성이 높아 routine 실험실 방법으로 유용성이 높을 것으로 생각되며, 또한 혈장 homocysteine의 측정은 만성신부전증 환자의 주요한 사망원인이 되는 폐쇄성 동맥질 환을 조기에 진단하거나, 혹은 homocysteine 농도를 저하시키는 치료를 실시 한 후 치료효과를 판단하기 위한 생화학적 marker로 활용될 수 있을 것으로 기대된다.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
• /
• pp.465-466
• /
• 2002

In any mechanical system consisting of gears, shafts and/or bearings, the majority of metallic particles deposited into and carried by the lubrication system originate from the deterioration of oil-wetted working surfaces, even in proper lubrication system, due to failure mechanism (s) such as wear, fatigue and fretting corrosion. Determination of the point at which transition from normal to abnormal or to actual damage occurs has become a focus of attention in research activities for years, because it has been recognized that reliable, economic operation can be achieved through appropriate preventative measures. Known collectively from 'all size wear debris analysis' as early failure detection, the methods of testing for damage differ considerably, range from a micron or a submicron size debris analysis to Magnetic Chip Detector (MCD) ferrous debris analysis. This paper will be focused on the utilization of the low-cost analysis techniques for evaluation of industrial machinery condition.

• International Journal of Contents
• /
• 제7권4호
• /
• pp.30-34
• /
• 2011

A Leader is a Coordinator that supports a set of processes to cooperate a given task. This concept is used in several domains such as distributed systems, parallelism and cooperative support for cooperative work. In completely asynchronous systems, there is no solution for the election problem satisfying both of safety and liveness properties in asynchronous distributed systems. Therefore, to solve the election problem in those systems, one property should be weaker than the other property. If an election algorithm strengthens the safety property in sacrifice of liveness property, it would not nearly progress. But on the contrary, an election algorithm strengthening the liveness property in sacrifice of the safety property would have the high probability of violating the safety property. In this paper, we presents a safety strengthened Leader Election protocol with an unreliable failure detector and analyses it in terms of safety and liveness properties in asynchronous distributed systems.

• International Journal of Contents
• /
• 제1권1호
• /
• pp.21-28
• /
• 2005

This paper is about the hardness of Leader Election problem in asynchronous distributed systems in which processes can crash but links are reliable. Recently, the hardness of a problem encountered in the systems is defined with respect to the difficulty to solve it despite failures: a problem is easy if it can be solved in presence of failures, otherwise it is hard [9]. It is shown in [9] that problems are classified as three classes: F (fault-tolerant), NF (Not fault-tolerant) and NFC (NF-completeness). Among those, the class NFC is the hardest problem to solve. It is also shown in [9] that the construction of Perfect Failure Detector (problem P) belongs to NFC. In this paper, we show that Leader Election is also one of NFC problems by using a general reduction protocol that reduces the Leader Election Problem to P. We use a formulation of the Leader Election problem as a prototype to show that it belongs to NFC.