• The Science & Technology
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• v.33 no.12 s.379
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• pp.10-11
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• 2000

우리나라의 핵융합실험은 대형의 토카막으로 자기 핵융합실험인데 막대한 국력을 자기 핵융합장치 토카막에만 집중하는 것보다 그 예산의 일부나마 레이저 핵융합연구에 돌려 미래의 에너지 기술전쟁에 대비하는 것이 바람직하다. 10~30년후 레이저 핵융합 분야의 연구에 있어서 기술종속국이 되지 않기 위해선 관련 기반연구에 대한 우선 투자가 필수적이라고 생각한다.

• Proceedings of the Korean Magnestics Society Conference
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• 2017.05a
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• pp.196-197
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• 2017

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.7
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• pp.875-880
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• 2007

Scientific challenges in the field of MR(magnetorheological) fluids and devices consist in the development of MR devices, the mathematical modeling and simulation of MR devices, and the development of (optimal) control algorithm for MR device systems. To take a maximum advantage of MR fluids in control applications a reliable mathematical model, which predicts their nonlinear characteristics, is needed. A inverse model of the MR device is required to calculate current(or voltage) input of MR damper, which generates required damping force. In this paper, we implemented test a bench for shear mode rotary MR damper and laboratory tests were performed to study the characteristics of the prototype shear-mode rotary MR damper. The direct identification and inverse dynamics modeling for shear mode rotary MR dampers using multi-layer neural networks are studied.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.412-416
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• 2006

A magnetic field oscillator was designed and made. The oscillator was installed around a water pipe and radiated into water which was provided for vegetables cultivation. The oscillator was made with a helmholtz coil and installed a magnetic field sensor inside. The class E amplifier circuit with frequency variance was also used. Hydroponic and soil cultural methods were used for cultivation of lettuce and chinese cabbage with magnetic field water and without. Vitamin C ingredients in the lettuce and chinese cabbage which were grown with magnetic field water were 2.8 times and 1.2 times higher than without the magnetic water. Moreover, the growth acceleration effect of vegetables was shown in lettuce cultivated with the magnetic field water.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.3-5
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• 2009

교류 자기장의 정밀측정, 자기장 측정기의교정 및 관련 시험 등 을 지원하기 위해 교류자기장 표준장치를 개발하였다. 주파수에 따른 확장분확도(expanded uncertainty, 2 $\sigma$)는 1 MBz 이하에서 0.16 %, 1 kHz $\sim$ 5 kHz 에서 0.26 %, 5 kHz $\sim$ 20 kHz에서 0.44 % 이었다. 측정결과에 대한 국제적 신뢰성 및 상호인증을 확보하기 위하여 핵심측정표준 국제비교(international key comparison)에 참여하였으며, 또한 측정능력, 교정 및 시험방법 등에 대한 국제적 전문가로부터 평가(peer review)를 수감하였다. 따라서 한국표준과학연구원 (KRISS)에서 교정 및 측정한 결과에 대해서는 국제적 상호인증을 받을 수 있다.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1123-1131
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• 2023

This study aimed to present a method to effectively suppress metal artifacts caused by spinal fusion surgery during spinal MRI study. For this purpose, a phantom made of spinal surgery screws was created to reproduce the metal artifact. Then, images were acquired with 1.5T and 3.0T MRI to evaluate changes in metal artifacts according to magnetic field strength. In addition, metal artifacts were evaluated by increasing the receive bandwidth to 200, 400 and 800 Hz/PX. As a result, metal artifacts occurring in images obtained from the 1.5T MRI decreased by approximately 52.2% compared to images obtained from the 3.0T MRI, showing a significant difference (p<0.05). In particular, the signal loss and signal pile up areas were reduced by approximately 52.81% and 42.71%, respectively, showing a significant effect in suppressing metal artifacts. On the other hand, when images were acquired while increasing the receive bandwidth from 200 to 800 Hz/PX, there was no significant effect, with a decrease of up to 8.93% for the 1.5T MRI and up to 10.98% for the 3.0T MRI (p>0.05). As a result of this study, increasing the receive bandwidth reduced signal loss and reduced some metal artifacts, but did not have a significant effect because it did not suppress signal pile up. However, when the magnetic field strength was reduced from 3.0T to 1.5T, signal loss and signal pile up were greatly reduced, effectively improving the metal artifact. Therefore, in order to suppress metal artifacts caused by spinal fusion surgery, study using a low magnetic field MRI can be said to be the most effective method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1620-1634
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• 1991

본 연구에서는 전기/자기 및 기계적 요소들이 복합되어 이루어진 자기부상 시 스템의 설현을 위한 기초단계로서 제어동역학(controlled dynamics) 측면에 입각한 모 델식을 본드선도 기법을 이용하여 보다 조직적으로 유도한다. 우선, 자속흐름 확장 및 자속 유출량을 고려하여 부상 시스템을 모델링하고 차량/레일 및 2차 현가(second ary suspension)장치를 포함한 자기부상 시스템을 모델링한다. 다음, 지지 및 안내 방향의 동역학을 동시에 고려한 2차원 자기부상 시스템을 본드선도의 다접점 필드(mu- ltiport field) 개념을 이용하여 모델링한다. 끝으로, 본드선도 기법으로 모델링된 2차원 자기부상 시스템의 안정도와 성능을 향상시키기 위하여 LOG/LTR(linear quadra- tic Gaussian control with loop transfer recovery) 제어시스템을 설계한다. LQG/ LTR 제어방법은 Doyle과 Stein에 의해 인성(stability-robustness) 문제와 주파수역 성능을 설계시에 직접 고려할 수 있는 강력한 선형 다변수 제어시스템 설곕방법으로 현재 널리 사용되고 있다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.140-143
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• 2003

자기부유기는 전자력을 이용해서 쇠구슬을 공중에 떠있게 할 수 있는 장치이다. 본 논문에서는 자기 부유기의 기본 원리와 모델링에 관해 소개하고, 디지털 신호처리와 PWM전력변환기를 사용한 자기 부유기를 직접 제작하고 실험을 통해 성능을 검증하였다. 자기부유기의 원리는 고속회전기에 사용되는 자기베어링이나 자기부상 열차의 부상 시스템에 응용될 수 있다. 또한 전기공학 분야의 다양한 교과과정에서 습득한 지식을 활용할 수 있는 학부 프로젝트 실험 주제로 적합하다.

• Journal of the Korean Magnetics Society
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• v.15 no.6
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• pp.307-310
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• 2005

To get the spatial feature of arterial pulse, we designed spatial pulse diagnostic apparatus (SPDA) using a 2-dimensional magnetoresistive sensor array. The magnetic field distribution fur magnet may was simulated using finite element method. We recognized that the field distribution of parallel magnet mays was more sensitive and uniformed than that of perpendicular one. Also the spatial displacements of magnet array were agreed with the output signal of magnetic tunnel junction (MTJ) sensor array.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4489-4493
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• 2014

LED light driving device has problems in efficiency and heating at higher than 150W. In addition, there is inconvenience in replacing the lighting device to another when W is not the same as the previous one. In this paper, a multi-channel LED light driver, driver embedded driver circuit in a multi-channel structure with a power system in the driver-interlocking structure was designed. With the auto control converter structure with a power efficiency above 93% and power factor above 0.98, the weight of the high efficiency LED lighting-actuating device in driver-interlocking structure, a driver in self-calibrating self-optimization structure. In this paper, at below 10% THD, the existing converter contrast weight was reduced by 40% or more.