• KSTLE International Journal
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• 제4권2호
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• pp.37-42
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• 2003

One of the obstacles for a magnetic bearing to be used in the wide range of industrial applications is the failure modes associated with magnetic bearings, which we don't expect for conventional passive bearings. These failure modes include electric power outage, power amplifier faults, position sensor faults, and the malfunction of controllers. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate in spite of some faults in the system. In this paper, we designed a fault-tolerant magnetic bearing system for a turbo-molecular vacuum pump. The system can cope with the actuator/amplifier faults which are the most common faults in a magnetic bearing system. We implemented the existing fault-tolerant algorithms to experimentally prove the adequacy of the algorithms for industrial applications. As it turns out, the system can operate even with three simultaneously failing poles out of eight actuator poles.

• 치과방사선
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• 제21권1호
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• pp.65-72
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• 1991

For the enhancement of a comprehension in temporomandibular joint radiographs, the author has compared and analysed the roentgenographic images of the temporomandibular joint of human dry skull which was taken by submentovertex projection, panoramic radiography, oblique lateral transcranial projection, corrected anterio-posterior tomogram and corrected lateral tomogram. The obtained results were as follows. 1. The submentovertex projection represented in detail the both poles and the posterior surface of the condylar head of the mandible. 2. The oblique lateral transcranial projection represented the articular space, the outer contour of the condylar head and the position of the condylar head within the mandibular fossa, but the relationship of the temporomandibular joint was not revealed accurate, because of the oblique direction of a central ray in taking radiographs. 3. The corrected antero-posterior tomogram was superior method in representation of roent- genographic images of the superior surface and the both poles of the condylar head and the corrected lateral tomogram was considered as the most accurate method among some radiographic techniques for the interpretation of articular space and condyle-fossa relationship. 4. It was possible to observe three-dimensionally the head of condyle with the combinated use of submentovertex projection, corrected antero-posterior tomogram and corrected lateral tomogram.

• 한국농공학회지
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• 제44권4호
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• pp.107-113
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• 2002

The pipe framed and arch shape plastic greenhouse, which is the most popular greenhouse in Korea, is relatively weak in snowdrift. Reinforcement of rigid frame or column is required to reduce the damage from heavy snow in this type. But additional rigid frames or columns decrease light transmissivity or workability, and increase construction cost. So it is desirable to prepare some temporary poles and to install them when the warning of heavy snow is announced. This study was carried out to develop the temporary pole supporting system using galvanized steel pipes for plastic housing and to evaluate the safe snow load on a temporary pole. A pipe connector, which is inserted in the top of pipe used in the temporary pole and supports the center purline, was designed and manufactured to be able to carry the upper loads safely. And a bearing plate was safely designed and manufactured in order to carry the loads acting on it to the ground. When temporary poles of ${\phi}$ 25 pipe are installed at 2.4m interval, it shows that the single span plastic greenhouses with 5~7 m width are able to support the additional snow depth of 13.9~25.3 cm beyond the snow load supported by main frame.

• 한국안전학회지
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• 제16권3호
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• pp.35-40
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• 2001

An internal finishing process applying Magnetic Abrasive Finishing (MAF) was proposed to produce smooth inner surfaces of tubes at a high rate. Since this process uses the tube rotation system, it has been considered applicable only to tubes which are rotatable at high speeds. Here development of the stainless tube(STS 304) rotation system to extend the scope of the application of the internal finishing process applying MAF was made. By the stainless tube(STS 304) rotation system, the abrasive magnetically attracted by the poles is rotated along the inner surface of the tube by magnetic force together with fixed poles, finishing the inner surface of the tube. The main results obtained are as follows : 1) The magnet abrasive finishing minimized influence due to external force because non-contact finishing, 2) The profile of surface roughness decreased very good in 11.4m/min range because abrasive size and speed, 3) The profile of surface roughness by flux density decreased in finishing speed 28m/min, 4) The profile of surface roughness by fled rate decreased in 0.16mm/rev and 0.18mm/rev.

• 조명전기설비학회논문지
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• 제23권6호
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• pp.118-124
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• 2009

본 연구에서는 콘크리트전주가 수직 및 80[$^{\circ}$] 경사 건주된 경우에 대한 강도시험을 통하여 보통지선이 없는 수평 지선의 시설 가능범위를 파악하기 위한 콘크리트전주의 강도특성시험을 수행하였다. 수직으로 건주된 전주에 대한 1주기 강도시험 결과 일반용, 중하중용, 고강도용 콘크리트전주의 안전율은 각기 2.8, 2.5, 2.1로서 모든 전주가 안전율 2.0이상은 확보하는 것으로 나타났다. 그러나 수직으로 건주된 전주 상부의 휨 정도가 2[$^{\circ}$] 이상일 때 전주에 균열이 발생하며, 이 때에 작용하는 하중은 천주의 설계하중과 유사한 값을 나타내었다. 따라서 현장에 시설된 전주가 견고한 지반에 2[$^{\circ}$]이상 휘어져 있는 전주라면 설계하중에 근접한 하중이 상시 작용하고 있는 상태이기 때문에 지선 및 지주 등을 시설하여 보강이 반드시 필요함을 알았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.870-872
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• 2002

본 연구는 탐지 대상물체의 형상인식이 가능한 비접촉, 원격 탐지장치의 개발에 관한 것이다. 형체인식용 비접촉 시스템은 주로 Magneto- lmpedance법과 Magneto-Inductance법이 있으며, Magneto-Inductance법은 왜곡이 적고, 인체나 탐지 대상물체에 손상을 가져오지 않는다. 본 연구에서는 2극으로 디자인 된 Magnetic Tomography System을 이용하여 물체의 위치에 따른 투자율 변화량을 계산 및 실측하였다.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.208-214
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• 2011

In this paper, a characteristics analysis and calculation of the suspending force of a novel bearingless switched reluctance motor (BLSRM) with hybrid stator poles is proposed. The operating principle and permeance are calculated to find an appropriate control scheme for a proposed motor. Furthermore, a mathematical model for suspending force is derived. Finite element analysis is also employed to compare with the expressions for suspending force. Finally, the validity of the structure and the mathematical model is verified by simulation results.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제2권2호
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• pp.141-148
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• 1995

In this paper we shall consider function p(z) analytic in the open unit circle D and the solutions y(z) of the differential equation y"(Z) ＋ p(z)y(z) = 0. (1.1) The ratio f(z) = u(z)/v(z) of any two independent solutions u(z) and v(z) of (1.1) will be function f(z), meromorphic in D with only simple poles, and such that f'(z) (equation omitted) 0. We shall say that a meromorphic function which satisfies these two condition belongs to the restricted class.(omitted)

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.100.2-100.2
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• 2008

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.577-580
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• 2012

국립전파연구원 고시인 전기통신설비의 기술기준에 관한 표준시험방법에서는 통신 설비에 대한 접지 저항 측정 방법으로 현재 2개의 보조극을 설치하여 측정하는 3점전위강하법을 사용할 것을 권고하고 있다. 하지만 이 방법은 보조극을 설치하기 위한 공간의 확보가 어려운 지역이나 험준한 산악 지역, 암반 지역 등에서는 적용이 불가능하여 현장에서의 어려움이 예상되고 있다. 이에 IEEE와 ITU-T에서 기준이 되는 접지저항값의 만족 여부 확인만을 위하여 제시하고 있는 2극 측정법을 알아보고 테스트베드를 이용한 시험 측정을 통하여 3점전위강하법과 2극 측정법에 의해 측정된 접지저항을 비교 분석하였다.