• 대한기계학회논문집
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• 제15권1호
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• pp.90-97
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• 1991

본 연구에서는 하이브리드 스텝핑 모터의 공진 배제를 위한 폐회로제어시스템 을 개발하였고 펄스 발생, 위치 및 속도변화, 가감속제어, 정여괴전방향결정, 카운트 및 스텝핑 모터의 온/오프기능 등을 하드웨어 대신 마이크로컴퓨터를 이용한 소프트웨 어로 대치하였으며, 구동회로의 복잡함을 피하기 위해 스텝핑 모터의 전용제어기인 PMM8713IC를 사용하였고 궤환정보는 샤프트 엔코더를 사용하였다.그리고 리드 스크 루우를 사용한 1축 테이블을 제작하여 개회로제어시와 폐회로제어시의 동특성 및 공진 현상을 검토하였다.

• Investigative Magnetic Resonance Imaging
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• 제20권3호
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• pp.175-180
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• 2016

Carbon monoxide (CO) intoxication is a leading cause of the variable neuropsychiatric impairment. Despite of widely known central nerve system complications after CO intoxication, peripheral neuropathy due to CO poisoning is rare and has been under-recognized. We report interesting case of a 29-year-old male who suffered from motor weakness and sensory abnormalities in his lower extremity following acute CO intoxication. The patient revealed direct and indirect signs of peripheral neuropathy of the left inferior gluteal and sciatic nerve on magnetic resonance imaging.

• Investigative Magnetic Resonance Imaging
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• 제16권2호
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• pp.136-141
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• 2012

목적: 정상인에서 항혈소판제제인 클로피도그렐이 손운동기능 과제를 수행하는 동안 운동기능의 생리학적 반응에 대한 약리적 조절효과를 알아보고자 하였다. 대상과 방법: 10명의 오른손잡이 정상인을 대상으로 클로피도그렐 사용전, 최대 복용량 복용후, 정상상태 유지시로 세번에 걸쳐 뇌기능 자기공명영상 데이터를 획득하였다. 운동과제로는 주먹을 쥐었다 폈다하는 운동을 시행하였고 3.0 테슬라 자기공명영상기기에서 혈액산소의존성(BOLD) 대조도를 획득하였으며 이를 위하여 $T2^*$ 강조 EPI 영상기법을 사용하였다. 뇌기능 자기공명영상 데이터의 영상전처리 및 통계분석은 SPM2를 사용하였다. 결과: 이차수준 분석에서 주운동영역을 포함하는 편측 감각운동중추의 활성화가 나타났다. 클로피도그렐 사용전의 활성화 화소수는 173, 최대 복용량 복용후 활성화 화소수는 1049, 정상상태 유지시 활성화 화소수는 673 이었다. 최대 T값을 기준으로 측정한 BOLD 신호의 강도변화는 관찰되지 않았다. 결론: 본 연구결과는 클로피도그렐에 의해 대뇌 운동 활성이 조절된다는 사실과 또한 뇌기능 자기공명영상이 이러한 변화를 감지할수 있을만큼 높은 민감성을 가진다는 사실을 제안하고 있다.

• Journal of Power Electronics
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• 제12권1호
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• pp.67-74
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• 2012

According to electrical output up rating of a permanent magnet motor and request to operate for a large variable speed range, resonance between structural natural vibration and electromagnetic force inside the motor can take place and make noise. This paper describes the mechanism of a resonance between them and noise lowering procedure by frequency shift when they are applied to the reluctance torque largely employed new motor named Permanent magnet Reluctance Motor (PRM).

• 전기학회논문지
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• 제62권10호
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• pp.1397-1402
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• 2013

This study researched cause of resonance noise for BLDC motor used in the refrigerator. it is difficult to measure dynamic characteristics for small sized fan & rotor system with conventional excitation method. Therefore this study performed electric exiting method and natural frequency method using microphone instead of conventional excitation and showed validity of these methods. Study result showed that tortional vibration frequency of fan & rotor system and natural bending frequency of the fan were matched with exciting frequency of BLDC motor caused by commutating ripple torque. And this frequency match caused resonance of the system. The study analyzed main parameters of this phenomenon and suggested alternative solution.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.416-421
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• 2001

It was firstly issued that frequently broken of Encoder installed at travelling motor during RTGC operation. Estimated as broken due to excessive vibration of traveling and motor manufacturer claimed it as resonance of motor base. The principal vibration of Encoder was caused by the rotating vibration component of motor and by traveling wheel. The component transmitted from the wheel didn't have great vibration by the resonance with motor and other parts. Therefore, the plans was tried to add the support point to prevent the Encoder shaft vibrated greatly and inhibit the vibration. These showed good results.

• 비파괴검사학회지
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• 제32권4호
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• pp.401-409
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• 2012

초음파 시험은 접착계면에서 발생하는 미접착 결함을 검출할 수 있는 다른 비파괴 시험보다 미접착 검출 능력이 월등히 뛰어나다. 하지만, 스틸 연소관, 내열 고무, 라이너 및 추진제로 구성된 고체 추진기관은 각 재질의 음향 임피던스의 큰 차이와 반사파의 중첩 때문에 초음파 신호를 분석하기에는 많은 어려움 있다. 그러므로 고체 추진기관의 미접착 결함을 검출하기 위한 초음파 시험은 자동화된 C-Scan 시스템을 이용하여 스틸 연소관과 내열 고무 계면의 극히 제한된 영역에서 적용되어 왔다. 기존의 초음파 시험은 대부분의 초음파가 음향 임피던스가 낮은 고무 재질에서 흡수되므로 고체 추진기관의 라이너와 추진제 사이의 미접착 결함을 검출할 수 없었고, 이런 문제점을 해결하기 위하여 초음파 공진법을 사용하여 주파수 스펙트럼으로부터 공진 주파수를 분석하였다. 본 논문은 초음파 공진 특성을 이용하여 라이너와 추진제 사이의 미접착 결함을 검출할 수 있는 기법에 대해 자세히 기술하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.264-269
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• 2008

This paper presents the summary of control of abnormal vibration found in the COP motors of a nuclear power plant. All six identical units of COP pump-motor assemblies showed unstable vibration pattern of which one or two showed higher vibration enough to exceed the allowable level from the installation stage. Many trials of test, measurement, overhaul and replacement had been repeated to investigate and solve the problem but only to reach unsatisfactory settlement. Recently several times of site tests are made and followed by significant diagnostic actions in which the authors group participated. It was found that the coupled shafting system of motor and pump is in close resonance with the $1^{st}$ shaft rotating speed. Redesign of topside motor bearing clearance is made to increase bearing stiffness and hence to avoid the resonance which consequently led to reduce the troubled vibration to allowable and stable status.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권5호
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• pp.309-317
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• 2004

This paper suggested the vibration characteristic improvement by variation mode of ring type ultrasonic motor. Design for the piezoelectric ceramic and elastic body of stator were calculated by the finite element method(FEM) that consider the resonance frequency, vibration mode and coupling efficiency etc. Through the result of vibration analysis from 6 order mode to 8 mode, the 7 order mode was gained very an excellent results that it was the coupling efficient, minimum power loss and bending vibration value. Here over 7 order mode, this paper was acquired that an output current for input voltage was very a large increased results. The result of vibration calculation, from thickness 0.5[mm] to 2[mm], knew the fact that the vibration displacement at 0.5[mm] is an high value too. From such result, this paper was manufactured the ultrasonic motor of outer diameter 5O[mm] , inter 22[mm] having the about 43.86[KHz] resonance frequency. We have gated that a simulation result is 42.2[KHz] and an experiment result is 43.86[KHzl The propriety of this paper was established though comparison. investigation of simulation and experiment result.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.343-343
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• 2008

Newly designed structure of a thin ultrasonic rotary motor was proposed. Thin brass plate was used as a cross shaped vibrator and eight ceramic plates were attached on the upper and bottom sides of the brass plate as in Figure 1. The thin type ultrasonic motor has the structure adherent piezoelectric ceramic on the top and bottom surface of the thin elastic body. The direction of polarization is decided so as to occur the elliptical displacement in regular sequence at touch point A, B, C and D of stator contacted with rotor. By applying two electric fields which have 90 degree phase difference on the ceramics, each contact points make rotational displacements as in figure 2. Finite element analysis program ATILA was used to find the optimal size of the stator. As a result of the simulation, elliptical displacements of the tips were obtained at off-resonance frequencies. The maximum displacements of the contact tips were obtained at the length of 16[mm], width of 6[mm] and thickness of 0.4[mm]. Changes of the resonance frequencies were inversely proportional to the length of ceramic and proportional to the width of ceramic. Elliptical motions of the contact tips. of the stator were consistently obtained at off resonance frequencies. From a prototype motor, speed of 600[rpm] was obtained at 20[Vrms].