• 한국자기학회지
• /
• 제17권3호
• /
• pp.141-146
• /
• 2007

MEMS 공정기법을 적용하여 새로운 형태의 LC 공진기형 자기센서를 제작하였다. 이 마이크로 LC 공진기는 솔레노이드형 마이크로인덕터에 연자성 마이크로와이어를 코어로 삽입하고 여기에 콘덴서를 병렬로 연결하여 구성하였다. 코어 자성 물질은 melt spinning 법으로 제조한 유리가 코팅된 $Co_{83.2}B_{3.3}Si_{5.9}Mn_{7.6}$ 마이크로와이어이다. 코어물질의 연자성을 개선하기 위하여 $150^{\circ}C$, $200^{\circ}C,\;250^{\circ}C,\;300^{\circ}C$ 등 여러 온도에서 1시간씩 진공 열처리하였다. MEMS 공정으로 제작된 솔레노이형 마이크로인덕터는 길이가 $500{\sim}1,000{\mu}m$ 이며 감은수는 $10{\sim}20$회이다. 외부자기장에 따른 본 마이크로인덕터의 최대 인덕턴스 변화율은 370%이었다. 초연자성 마이크로와이어의 투자율이 외부자기장에 따라 급격히 변하기 때문에 인덕턴스변화율이나 LC 공진기의 자기임피던스 변화율(MIR)이 급속하게 변한다. 최대감도를 얻기 위해서 MIR 곡선은 정교하게 조절할 수 있다. 마이크로인덕터와 멀티바이브 레어터 회로로 구성된 원형 자기센서소자를 제작하여 시험동작을 하는데 성공하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권7호
• /
• pp.826-831
• /
• 2003

The purpose of this study was to measure the surface tension of hard water through electro-magnetic field for investigating the effect of electro-magnetic water treatment. The maximum reduction of surface tension was 8% comparing to the no treatment case. When the flow velocity through the permanent magnetic device (PMD) was 6.3 m/s, sample of hard water had the minimum surface tension.

• Journal of Magnetics
• /
• 제3권1호
• /
• pp.15-20
• /
• 1998

A newly designed magnetic annealing apparatus was used for the treatment of Fe-3%Si steels. With the help of this device, the effect of magnetic annealing on magnetostriction was studied in a wide spectrum of external elastic stresses. It was shown that magnetostriction properties of Fe-Si steels were improved in the compressed state through magnetic annealing, while those in the unstressed state or under tensiion were found to be practically unchanged.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.381-382
• /
• 2007

Recently fishing industry is interested in efficient and automated fishing implementations to reach the level of the international leading technology. One of the important device used in fishing boat is an automated electric compass that harnesses the GPS and terrestrial magnetic sensor. The electric compass is desired to be minimized in size while keeping a high effectiveness in the characteristic of a magnetic compass. This device also can be used as a heading angle sensor to construct auto-navigation system in a small size of ships. However, there exists measurement errors induced from the slope of terrestrial magnetic sensor caused by the motion of boat. In this paper, a method has been proposed removing the measurement error arising from the slope of terrestrial magnetic sensor when the ship is in motion. We have designed a sensor with two DOF(degree of freedom) and a weight to maintain the horizontality of the sensor. Through this research, the hardware has been designed and also a test has been performed. The test shows a promissory result.

• 한국자기학회지
• /
• 제24권3호
• /
• pp.90-96
• /
• 2014

요골동맥의 움직임에 따라 손목의 "관" 위치에 놓인 영구자석이 요동함으로 자기장의 변화를 생성하였다. 맥동에 의존하는 자기장을 감지하는 홀소자가 구비된 집게형맥진기의 출력신호인 맥진파형 특성을 분석하였다. 유한요소법으로 전산모사한 자기장 파형과 실제 맥진 파형의 시간 특징점들은 거의 일치하였다. 한 개의 원통 소형 영구자석의 자기장 분포의 변화를 감지하는 홀소자 집게형맥진기 시뮬레이터를 제작하여 재현성과 유효성 있는 한방진단기기로 활용하는 기틀을 마련하였다.

• Journal of Magnetics
• /
• 제12권2호
• /
• pp.89-92
• /
• 2007

The authors propose a magnetic actuator for use as a navigation system for capsule endoscopes. The actuator is composed of a capsule dummy, a permanent magnet inside the capsule, and an external spiral structure. The device rotates and propels wirelessly when exposed to an external rotational magnetic field. In this study we measured the effect of the spiral shape on the velocity and thrust force properties. According to our experimental results, the actuator obtained a maximum velocity and thrust force when the spiral angle was set at 45 degrees, the number of spirals was set at 4, and the spiral-height was set at 1-mmf. We also conducted a motion test in the large intestine of a pig placed on a 30 degrees slope. The actuator passed through a 700 mm length of the intestine in about 300 s. The device also managed to travel up and down the 30 degrees slope with no difficulty whatsoever. Our results demonstrate the great potential of this actuator for use as a navigation system for capsule endoscopes.

• 한국초전도ㆍ저온공학회논문지
• /
• 제21권1호
• /
• pp.10-14
• /
• 2019

Radio-frequency (RF) amplifiers based on direct current (DC) superconducting quantum interference device (SQUID) have low-noise performance for precision physics experiments. Gain curves of SQUID RF amplifiers depend on several parameters of the SQUID and operation conditions. We are developing SQUID RF amplifiers for application to measure very weak RF signals from ultra-low-temperature high-magnetic-field microwave cavity in axion search experiments. In this study, we designed, fabricated and characterized SQUID RF amplifiers with different SQUID parameters, such as number of input coil turn, shunt resistance value of the junction and coupling capacitance in the input coil, and compared the results.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.652-655
• /
• 2003

This paper is about the recent development of the magnetic impact actuator for endoscope. The developed magnetic impact actuator has many problems to arrange in the system body. Because the magnetic impact actuator need a permanent magnet as an impacter, so the magnetic interference among magnets can not be eliminated. This interference causes the system size bigger. We need a new actuator design to solve these problems. One of the good solutions is to use the closed electro-magnetic circuit. This kind of circuit enhances the actuators to be independent. It is written about the design of the electro-magnetic circuit and simulation using Maxwell(version 9.0)

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.15-17
• /
• 2005

In this study, tunable dielectric materials are important for resonator, variable capacitor, phased array antenna and other devices application. In this paper, Dielectric constant increased and tuning range increased with the increased of $BaSrTiO_3/Li_{2}CO_{3}$ content, which probably can be explained by the substitution of Ba3+, Li1+ on BaTiO3 lattice. The tunability and dielectric loss of the $BaSrTiO_2/Li_{2}CO_{3}$ thick film, sintered at $1150^{\circ}C$, were about 43 % and 0.234 at 10$\sim$15 MHz, respectively. In case of BaSrTi/MgO, Dielectric constant decreased and tenability increased with the added of $BaSrTiO_3/MgO$. The ferroelectrics properties were distinct when adding Li to BST ceramic thick film, and paraelectrics pattern was distinct when adding Mg.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
• /
• pp.2013-2015
• /
• 2005

In this paper, Effect of $BaSrTiO_3/Li_2CO_3$ on low temperature sintering and dielectric property of thick films has been investigated for variable capacitor on high frequency. The thick films were fabricated by the tape casting and then the structural and dielectric properties as a function of an addition composition ratio and sintering temperature were studied. For the thick film sintered at $1050^{\circ}C$, it was densified to 96% of $BaSrTiO_3$ theoretical density by the addition of 10 $wt{\cdot}%$ $BaSrTiO_3/Li_2CO_3$. Dielectric constant increased and Curie temperature lowered with the increased of $BaSrTiO_3/Li_2CO_3$ content, which probably can be explained by the substitution of $Ba^{3+},Li^{1+}$ on $RaTiO_3$ lattice. The tunability and dielectric loss of the $BaSrTiO_3/Li_2CO_3$ thick film, sintered at $1350^{\circ}C$, were about 26% and 0.234 at $10{\sim}15MHz$, respectively.