• Journal of the Korean Magnetics Society
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• v.12 no.4
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• pp.149-153
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• 2002

Flux-gate magnetometer has been still used for low field magnetic field measurement with portability, low power consumption, and high reliability. In many applications, flux-gate magnetometer measures not absolute values but changes of the earth magnetic field. For the eia magnetic field change measurements, we have constructed a high sensitive 3-axis flux-gate magnetometer of which measuring ranges is ${\pm}$1000 nT and noise level is 5pT/√㎐ at 1 ㎐. Using this magnetometer, we can compensate the earth magnetic field of ${\pm}$50,000 nT with successive approximation methods using microcomputer. After earth magnetic field compensation, we could measure earth magnetic field changes with ${\pm}$100 nT measuring ranges.

• Proceedings of the Korean Magnestics Society Conference
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• 1992.03a
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• pp.22-23
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• 1992

• Progress in Medical Physics
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• v.26 no.4
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• pp.208-214
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• 2015

The aim of this study is to investigate the effect of low magnetic field on dose distribution in the partial-breast irradiation (PBI). Eleven patients with an invasive early-stage breast carcinoma were treated prospectively with PBI using 38.5 Gy delivered in 10 fractions using the $ViewRay^{(R)}$ system. For each of the treatment plans, dose distribution was calculated with magnetic field and without magnetic field, and the difference between dose and volume for each organ were evaluated. For planning target volume (PTV), the analysis included the point minimum ($D_{min}$), maximum, mean dose ($D_{mean}$) and volume receiving at least 90% ($V_{90%}$), 95% ($V_{95%}$) and 107% ($V_{107%}$) of the prescribed dose, respectively. For organs at risk (OARs), the ipsilateral lung was analyzed with $D_{mean}$ and the volume receiving 20 Gy ($V_{20\;Gy}$), and the contralateral lung was analyzed with only $D_{mean}$. The heart was analyzed with $D_{mean}$, $D_{max}$, and $V_{20\;Gy}$, and both inner and outer shells were analyzed with the point $D_{min}$, $D_{max}$ and $D_{mean}$, respectively. For PTV, the effect of low magnetic field on dose distribution showed a difference of up to 2% for volume change and 4 Gy for dose. In OARs analysis, the significant effect of the magnetic field was not observed. Despite small deviation values, the average difference of mean dose values showed significant difference (p<0.001), but there was no difference of point minimum dose values in both sehll structures. The largest deviation for the average difference of $D_{max}$ in the outer shell structure was $5.0{\pm}10.5Gy$ (p=0.148). The effect of low magnetic field of 0.35 T on dose deposition by a Co-60 beam was not significantly observed within the body for PBI IMRT plans. The dose deposition was only appreciable outside the body, where a dose build-up due to contaminated electrons generated in the treatment head and scattered electrons formed near the body surface.

• Progress in Medical Physics
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• v.7 no.2
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• pp.41-46
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• 1996

A further attempt is made to reconfirm the previous identified proton NMR signals regarded as a cancer maker. The result of the attempt shows that the NMR signals clearly correspond to the four aromatic proton NMR signals of m-hydroxyphenyl.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.619_620
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• 2009

본 논문은 자기장을 이용하여 전류를 안정화시켜 정밀전류를 발생 시킬 수 있는 장치에 관한 연구이다. 일반적으로 전류를 안정화 시키는 방법은 전류회로에 직렬로 저항을 연결하여 저항 양단에 유도되는 전압을 측정하여 전류를 제어하는 방법을 많이 사용한다. 그러나 이 방법은 정밀한 전류를 제어하기 위하여 직렬로 연결되는 저항값이 커야하며, 또한 전류에 의해 발생되는 열로 인해 저항값이 증가하기 때문에 정밀한 제어가 어렵다. 이러한 단점을 보완 할 수 있는 방법으로 전류회로에 직렬로 코일을 연결하여 전류가 변화면 코일속에 자기장이 변화는 원리를 이용하여 전류를 안정화시켜 정밀전류를 발생 할 수 있다. 본 연구에서는 저자기장 국가표준 확립 및 물리고유상수인 양성자 자기회전비율 측정을 위해 원자자기공명 방법을 이용하여 직류전류를 1 A 범위에서 $0.1{\mu}A$ 수준으로 안정화 시켰다.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.168-169
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• 2003

최근 세계적 주목을 받고 있는 spin FET 소자는 반도체에 주입된 spin 편향된 전자가 gate voltage(V$_{G}$)에 의해 반도체 계면에 유도된 전기장의 영향을 받아, Spin 세차운동을 하는 mechanism(Rashba 효과)이 근간을 이루고 있다. 작은 band gap을 가지는 반도체(narrow gap 반도체)는 작은 유효질량의 전자에 의해서 이러한 Rashba 효과를 크게 할 수 있어서, spin FET 구현을 위한 강력한 후보이며, 요즘 한창 연구되고 있는 주제이기도 하다. Rashba 효과가 저자기장 영역에서의 weak antilocalization효과로 나타남을 이용하여, 본 논문에서는 metal gate가 형성된 HgCdTe FET를 제작하여(FET1 시료, Fig. 1(a)참조), V$_{G}$에 따른 weak localization(WL) 및 weak antilocalization(WAL) 효과를 얻었다. 또한, Rashba 효과에 의한 spin 세차운동을 측정할 수 있는 소자(FET3 시료, Fig.1(b) 참조)를 제작하여 spin FET 구조에 대하여 연구하였다.

• Journal of the Korean Magnetics Society
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• v.24 no.4
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• pp.123-127
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• 2014

We developed a digital 3-axis flux-gate magnetometer for magnetic field signal measurement from warship during demagnetizing and degaussing processes. For the magnetometer design, we considered following points; the distance between magnetic field measurement station and magnetometer located under sea is about several 100 m, the magnetometer is exposed to magnetic field of ${\pm}1mT$ during demagnetizing process, and magnetometer is located under the sea about 30 m depth. To overcome long distance problem, magnetometer could be operated on wide input supply voltage range of 16~36 V using DC/DC converter, and for the data communication between the magnetometer and measurement station a RS422 serial interface was employed. To improve perming effect due to the ${\pm}1mT$ during demagnetizing process, magnetometer could be compensated external magnetic field up to ${\pm}1mT$ but magnetic field measuring rang is only ${\pm}100{\mu}T$. The perming effect was about ${\pm}2nT$ under ${\pm}1mT$ external magnetic field. The magnetometer was tested water vessel with air pressure up to 6 bar for the sea water pressure problems. Linearity of the magnetometer was better than 0.01 % in the measuring range of ${\pm}0.1mT$ and noise level was $30pT/\sqrt{Hz}$ at 1 Hz.

• Journal of the Korean Magnetics Society
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• v.13 no.6
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• pp.251-256
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• 2003

We have developed the quality analysis system for magnetic field effect of cathode-ray tube that is used a monitor, TV and medical appliance. We designed and constructed the large 3-axis square coil (2 m length) system for the generation of 3-component magnetic field using power supply, magnetometer and computer below 0.2 mT range. The coil constant is 30.31 ${\mu}$T, 29.73 ${\mu}$T and 30.51 ${\mu}$T for the X, Y and Z axis square coil respectively. The magnetic field resolution was 0.01 T. The uniformity of magnetic field was measured within 1 ％ in the range of 12 cm.

• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.692-697
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• 1995

The chemical compositions and possible structure for the complex of B15C5 with Nd(Ⅲ) have been determined by NMR spectrophotometry in acetone-d6. On the stepwise additions of Nd(Ⅲ) to B15C5 solution of constant concentration, all the resonances shifted to downfield and the mole ratio of B15C5 to Nd(Ⅲ) was found to be 1 : 1. From the line broadening of proton peaks of NMR spectra, it was found that oxygen atoms in B15C5 interact with Nd(Ⅲ) ion. And in IR spectra of Nd(Ⅲ)-B15C5 complex, the band of asymmetric C-C-O stretching vibration shifted to a lower frequency region upon complexation. We have proposed the possible structure of the Nd(Ⅲ)-B15C5 coordinated with the five ether oxygen atoms and with the three bidentate nitrato groups.

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.178-181
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• 2010

Search coil magnetometer has been used for detection of ac magnetic field with high sensitivity. To reduce demagnetizing factor of core and increase S/N ratio of search coil magnetometer, the core was divided by two parts and coil was wound on each cores. Two coils were connected serially and put into amplifier as differential mode. Constructed 120 mm length search coil magnetometer shows linearity of 0.03%, sensitivity of 9.3 mV/nT, and resolution of 20 pT at 1 Hz.