• 한국음향학회지
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• 제13권3호
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• pp.78-84
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• 1994

보청기가 자계 pick-up 코일을 구비하고 있고, 전화 수화기에서 충분한 자계를 발생할 경우의 전화 수화기와 보청기의 자기결합을 이용한 전화기를 보청기 호환성 전화기 (hearing-aid-compatible telephone)라고 한다. 본 고에서는 보청기와 전화 수화기의 결합방법과 자계결합에 관한 국제 기준을 고찰하여, 국내의 보청기 호환성 전화기의 자계 기준 및 측정법에 관한 검토사항을 제시한다.

• Annals of Clinical Neurophysiology
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• 제3권2호
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• pp.160-163
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• 2001

Mirror movements in adult is usually accompanied with various clinical syndromes. But the pathogenesis of mirror movement is not clearly understood. A 20-year-old man visited with complaining of mirror movements in both hands, ophthalmoplegia and sensorineural hearing loss. He underwent through electromyography, transcranial magnetic stimulation, and functional magnetic resonance image. And we concluded that the mechanisms of his mirror movements were both ipsilateral innervated corticospinal tract and simultaneous activation of both motor cortex.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.457-460
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• 2005

When a hearing aid' s user is listening through telephone or cellular phone, he/she usually suffers from severe electrical magnetic interference noise. It is because hearing aids amplify voice signal as well as background noise. A telecoil, an induction coil, is a possible solution for the problem. Because a telecoil has the characteristic of high pass filter, it has some problem of resulting increased high frequency noise. For solving this problem, we can use a capacitor connected with the telecoil in parallel. According to capacitance, receiving signal quality may change. In this paper, proper capacitor values for the best sound quality are investigated by experimental work.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.243-247
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• 1996

Electro-magnetic type implantable middle ear hearing aid has been empirically developed. But for further improvement of the system performance more quantitative approach is necessary. In this paper, we analyzed vibrating transducer which is most important to design the system, appropriate for given hearing level, and implemented it. Using this transducer, implantable hearing aid system are developed. To verify the design process, we experimented with driving metal strip by the developed system. From the experiment, frequency response of implemented device showed good characteristic at audio frequency and we confirmed that each part of the developed system operated well.

• Journal of Korean Neurosurgical Society
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• 제40권5호
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• pp.336-341
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• 2006

Objective : The authors conducted a retrospective study to evaluate the preservation rates of serviceable hearing and to determine its prognostic factors after gamma knife stereotactic radiosurgery[GK SRS] in the patient with vestibular schwannomas. Methods : Between December 1997 and March 2005, 54 patients with a sporadic vestibular schwannoma and serviceable hearing [Gardner Robertson grade I-II] were enrolled in this study. Electronic database of medical records and radiological examinations before and after GK SRS were investigated to the last follow up. The mean marginal dose was $12.3{\pm}0.7Gy$. The mean maximum dose delivered to the tumor center was 24.7Gy [$22{\sim}30Gy$]. The median tumor volume was 2cc [$0.1{\sim}9.1cc$]. The median follow-up period of magnetic resonance[MR] imaging was 31 months [$6{\sim}99\;months$], and the mean follow-up period of audiometry was 24 months [$4{\sim}70\;months$]. Results : The tumor control rate was 100% in the patients with the follow up period more than 2 years. The trigeminal and facial nerve preservation rates were 98% and 100%, respectively. Twenty-eight [52%] of the 54 patients preserved serviceable hearing and 16 [30%] patients retained their pre-GK G-R grade level after GK SRS. In the univariate and multivariate analysis, there was no significant prognostic factor in preservation of the serviceable hearing. Conclusion : The hearing preservation rate is still unsatisfactory compared with the results of other cranial nerve preservation and tumor control in the treatment of vestibular schwannoma by GK SRS. More sophisticated strategy during and after GK SRS is necessary to improve long-term hearing preservation.

• 한국소음진동공학회논문집
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• 제14권5호
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• pp.439-448
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• 2004

Magnetic bearing is an attractive device in precision engineering field because of its non-contacting nature and controllability of its dynamic characteristics. This paper provides a method of designing a sliding mode control for an active magnetic hearing(AMB) system which is used to support the elevation axis of a target tracking sight instead of mechanical bearings to eliminate the effect of mechanical friction. In such system, the axis should be levitated and supported within a predetermined air gap while AMB is excited by base motion. Experimental results showed that the sliding mode control is effective in disturbance rejection than conventional PID-control without any additive measurements.

• 대한방사선기술학회지:방사선기술과학
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• 제40권1호
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• pp.19-25
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• 2017

본 연구는 1.5 T와 3.0 T Magnetic Resonance Imaging에서 Bone-Anchored Hearing Aid (BAHA) implant의 수평인력, 회전력, 그리고 자화감수성 인공물의 크기를 표준측정 방법에 의해 측정하여 MR 안전성을 평가하였다. BAHA implant의 고정장치와 지지대는 0.5%의 철(iron)이 포함 된 티타늄으로 만들어졌으며, 길이는 10 mm (고정장치 4 mm, 지지대 6 mm), 최대 직경은 7.0 mm이다. 수평인력 측정장치와 자화감수성 인공물 측정장치는 각각 American Society for Testing and Materials (ASTM) F2052-06, F2119-07을 참조하여 아크릴을 이용해 제작했으며, 회전력 측정은 원형 플라스틱 용기를 이용한 측정장치를 사용하였다. 자기유도에 의한 BAHA implnat의 수평인력은 주자장이 가장 큰 지점인 96 cm지점에서 최대 변위각을 측정하였고, 회전력은 원형용기 내부의 $45^{\circ}$간격의 실선 위에 놓았을 때 나타난 회전형태를 정성적 평가기준으로 측정하였다. 자화감수성 인공물은 황산구리($CuS0_4$) 용액이 채워진 용기의 중앙에 BAHA implant를 매달아 영상을 획득한 후 Susceptibility Artifact Measurement (SAM) software를 이용해 크기를 측정하였다. 측정결과 수평인력은 1.5 T와 3.0 T에서 변위각과 변위력은 모두 0으로 나타났다. 회전력은 1.5 T에서는 0(no torque), 3.0 T에서는 +1(mild torque)로 나타났다. 자화감수성 인공물은 최소 13.20 mm, 최대 38.91 mm의 크기로 나타났다. 따라서 1.5 T, 3.0 T의 MR 환경에서 BAHA implant는 환자에게 안전하다.

• 동력기계공학회지
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• 제5권4호
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• pp.53-60
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• 2001

This paper considers a modeling for the MIMO magnetic bearing system. The rotor is flexible and has a complex shape. To obtain the nominal plant transfer functions, we perform a numerical analysis by using the finite element method(F.E.M.) for the rotor's dynamics, and make a nominal model by reducing the modes from the results. And, we have experimented on the frequency response by a closed-loop identification method, and compared it with the simulation's result on the closed-loop control system.

• Investigative Magnetic Resonance Imaging
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• 제22권4호
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• pp.249-253
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• 2018

Superficial siderosis of the central nervous system (CNS) is a progressive and debilitating neurological disease manifesting sensorineural hearing loss, cerebellar ataxia, and pyramidal tract signs. Chronic extravasation of blood into the subarachnoid space results in the accumulation of hemoglobin derivate in the subpial layer of the CNS, which is toxic to the neural tissues. Craniopharyngioma is a benign third ventricle tumor, which rarely presents with tumor bleeding. We report a rare case of superficial siderosis associated with craniopharyngioma with intratumoral hemorrhage in a patient with no history of prior trauma or CNS surgery.

• 한국임상수의학회지
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• 제31권2호
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• pp.129-132
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• 2014

4년령의 암컷 보더 콜리가 청각장애 평가를 위해 내원하였다. 청력 소실의 원인을 확인하기 위해 임상 검사, 신경계 검사, 검이경, 자기 공명 검사법이 실시되었지만, 특별한 이상을 확인할 수 없었다. 청력 소실을 평가하기 위해 뇌간 청각유발전위 검사가 실시되었고, 양측성 감각신경성난청을 확인하였다. 여러 검사와 병력 확인을 통해 후천적 청력 소실의 가능한 원인들을 배제하여 유전성의 양측 후발성 감각신경성난청으로 잠정 진단하였다. 이 보고는 개에서도 사람에서 보고된 유전성의 후발성 감각신경성난청이 있을 수 있다는 것을 제안한다.