• 대한의용생체공학회:의공학회지
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• 제35권4호
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• pp.105-110
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• 2014

For the combination of MRI and magnetic particle hyperthermia(MPH), we investigated the relative heating efficiency with respect to the strength of the static magnetic field under which the magnetic nanoparticles are to be heated by RF magnetic field. We performed nanoparticle heating experiments at the fringe field of 3T MRI magnet with applying the RF magnetic field perpendicularly to the static magnetic field. The static field strengths were 0T, 0.1T, 0.2T, and 0.3T. To prevent the coil heat from conducting to the nanoparticle suspension, we cooled the heating solenoid coil with temperature-controlled water with applying heat insulators between the solenoid coil and the nanoparticle container. We observed significant decrease of heat generation, up to 6% at 0.3T(100% at 0T), due to the magnetic saturation of the nanoparticles of 15 nm diameter under the static field. We think MPH is still feasible at low magnetic field lower than 0.3T if stronger RF magnetic field generation is permitted.

• Journal of Magnetics
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• 제22권1호
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• pp.14-22
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• 2017

The NMR's probe consists of the static magnetic field generator (magnetic source) and the RF coil. It is very strict for the homogeneity of the static magnetic field intensity of the magnetic source, so the cost of the magnetic source is more expensive in the entire nuclear magnetic resonance instrument. The magnetic source generally consists of electromagnet, permanent magnet and superconducting magnet. The permanent magnet basically needs not to spend on operation and maintenance and its cost of manufacture is much cheaper than the superconducting magnet. Therefore, the permanent magnet may be the only choice for the static magnetic field device if we want to use the magnetic resonance instrument as an analyzer for production by reducing price. A new probe magnet was developed on the basis of the permanent magnet ring in this paper to provide a technological way for reducing the manufacturing cost, weight and volume of the existing nuclear magnetic resonance instrument (including MRI) probe.

• 한국군사과학기술학회지
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• 제10권4호
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• pp.38-51
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• 2007

This paper describes research results for the measurement and analysis method of magnetic signatures generated from the ship's magnetic mock-up model. In this paper, we present the theoretical and experimental techniques for the separation of the permanent and the induced magnetic field from the measured magnetic signature of the mock-up model. Also, we describe the prediction method of the induced magnetic field generated from mock-up model using the Magnet s/w, one of the FEM analysis tools for the electro-magnetic field and the magnetic dipole modelling method based on the least square techniques. The proposed modelling and analysis methods can be used for the prediction and the analysis of the static magnetic field generated from the real naval ship as well as the mock-up model.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.242-242
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• 2002

The Earth's magnetic field acquired from KOMPSAT-1's TAM (Three-Axis Magnetometer) between June 19th and 21st 2000 was analyzed. The TAM, one of the KOMPSAT-1's Attitude and Orbit Control Subsystems, plays an important role in determining and controlling the satellite's attitude. This also can provide new insight on the Earth's magnetic field. By transforming the satellite coordinate from ECI to ECEF, spherical coordinate of total magnetic field was achieved. These data were grouped into dusk (ascending) and dawn (descending) data sets, based on their local magnetic times. This partitioning is essential for performing 1-D WCA (Wavenumber Correlation Analysis). Also, this enhances the perception of external fields in the Kompsat-1's TAM magnetic maps that were compiled according to different local. The dusk and dawn data are processed independently and then merged to produce a total field magnetic anomaly map. To extract static and dynamic components, the 1-D and 2-D WCAs were applied to the sub-parallel neighboring tracks and dawn-dusk data sets. The static components were compared with the IGRF, the global spherical harmonic magnetic field model. The static and dynamic components were analyzed in terms of corefield, external, and crustal signals based on their origins.

• 한국자기학회지
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• 제17권6호
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• pp.259-264
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• 2007

본 논문에서는 모델 함정에 의해 발생하는 정 자기장 신호 특성을 수학적으로 모델링하는 방법에 대해 기술하고 있다. 특정 위치에 설치된 자기센서들에 의해 계측된 자기장 신호 값들로 부터 특이치 분해(singular value decomposition) 방법을 이용한 등가 자기원 다이폴 모델링 기법을 제안하였으며, 제안된 기법의 타당성은 비자성 자기실험실에서 측정된 자기장 값들과의 비교를 통해 성공적으로 검증되었다. 본 논문에서 제안된 기법은 모델 함정 뿐 만 아니라 실 함정에서의 다양한 심도 변화에 따른 정 자기장 신호 분포 특성 예측 시 직접 활용이 가능하다.

• Food Science and Biotechnology
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• 제15권6호
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• pp.833-837
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• 2006

To determine whether alcohol-treated rat liver cells can be protected by a static magnetic field (SMF), we analyzed the blood chemistry and histology of hepatic tissue removed from alcohol-exposed rats that had been exposed to a static magnetic field. The rats were exposed to a 0.3 tesla (3,000 gauss) magnetic field (MF) for 24 hr daily for 5 weeks with appropriate controls. Glutamic pyruvic transaminase activity and the triglyceride levels in animals exposed to the north (N) or south (S) pole of the MF decreased significantly (p<0.01 and p<0.05, respectively) compared with negative control animals with alcohol exposure. A histological examination of hepatic tissue revealed a moderate to severe accumulation of fat vacuoles of various sizes in the cytoplasm of the hepatocytes of animals in the negative control group throughout the study; whereas in groups exposed to the MF poles, fewer fat vacuoles were seen compared with the negative control group. Electron microscopic observations showed that exposure to the N or S pole protected organelles, including the nucleus, from damage during exposure to this toxic agent, as indicated by the fact that the nucleus and the mithochondria virtually retained their shape throughout this study. These results suggest that exposure to a SMF could be an excellent way of protecting against alcohol-induced damage to the rat liver cell.

• 대한치과교정학회지
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• 제27권4호
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• pp.623-632
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• 1997

정자기장과 맥동전자기장이 배양 조골세포에 미치는 영향을 알아보고자 MC3T3-E1세포를 각 자기장하에서 배양하여 ALP활성도와 DNA의 합성능을 평가한 결과 다음과 같은 결과를 얻었다. 1. 정자기장을 가한 군에서 자석을 1,2,3개 가한 군($51\~114.8mT$)에서 대조군에 비하여 ALP의 유의성있는 증가가 나타났으며(P<0.05), 자석을 4개 5개 가한 군(150mT)에서는 대조군에 비하여 ALP활성도에 차이가 나타나지 않았다. 2. 맥동성 전자기장에서는 대조군에 비하여 ALP활성도에 유의한 차이가 나타나지 않았다. 3. DNA합성능은 정자기장과 맥동성 전자기장을 가한 군 모두 대조군에 비하여 유의한 차이가 나타나지 않았다. 이상의 결과 정자기장에 의한 교정력은 골세포의 대사과정에 변화를 줄 수 있으므로, 치아이동에 어떠한 영항을 줄 수 있을 것으로 사료된다.

• 한국안전학회지
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• 제22권6호
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• pp.87-90
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• 2007

최근 의료분야에서 인체의 생리학적 조직에 정자계가 영향을 미치는 것으로 밝혀짐에 따라 정자계를 사용하는 의료장비의 중요성이 대두되고 있다. 본 연구의 목적은 자속의 영향에 의한 혈중 산소 포화 농도의 변화를 평가하는 것이다. 본 연구의 결과는 검지 손가락에 정자계 쌍극자가 맞추어졌을 때 혈중 산소포화 농도가 증가한다는 것을 보여준다.

• 한국정보통신학회논문지
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• 제12권8호
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• pp.1473-1480
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• 2008

비스무스는 융점이 낮아 취급이 용이하여 반자성체로서 전자기 차폐에 어떤 영향이 있는지 실험하기 쉽다. 그러나 실제 실험 재료를 원통으로 제작하여 측정된 경우를 찾아 볼 수 없다. 순수 비스무스는 반자성체로서 전자기 차폐에 어떤 영향이 있는가를 알기 위해서 비스무스를 다른 재료와 비교하기 위해서 원통으로 제조하였고 구리, 알루미늄, 철, 스텐레스 스틸도 원통을 만들어 정전차폐와 자기차폐를 저주파대에서 주파수 별로 측정하여 비교하였다. 그 결과 도표와 같이 구리와 비스무스 이중차폐가정전기에서는 제일 좋은 수치가 나왔다. 자기차폐에서는 철은 역시 가장 좋은 수치가 나왔고 비스무스는 별영향이 없이 나왔다.

• Journal of the Optical Society of Korea
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• 제19권6호
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• pp.575-585
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• 2015

Magnetic field in magnetic bearings is the physical medium to realize magnetic levitation, the distribution of the magnetic field determines the operating performance of magnetic bearings. In this paper, a thin-slice Fiber Bragg Grating-Giant Magnetostrictive Material magnetic sensor used for the air gap of magnetic bearings was proposed and tested in the condition of dynamic magnetic field. The static property of the sensor was calibrated and a polynomial curve was fitted to describe the performance of the sensor. Measurement of dynamic magnetic field with different frequencies in magnetic bearings was implemented. Comparing with the finite element simulations, the results showed the DC component of the magnetic field was detected by the sensor and error was less than 5.87%.