• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1109-1112
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• 2015

A milatary ship without degaussing coil has a vertical magnetization to compensate magnetization induced by the vertical magnetic field component of earth magnetic field during demagnetization process. Flash D is very useful to acquire vertical magnetization. However this is hard to predict vertical magnetization. This experiment was investicated on another method, which used the only vertical bias magentic field. The specimens were prepared by thin Zn coated steel sheet with a thickness of 0.15mm. The shapes of 3 specimes was rectangular, triangular and circular cylinders. These shapes were corresponded to the shapes of bow, mid and stern of a vessel. Through FEM analysis, the difference of magnetic signatures for these specimens was recognized and the residual magnetization curve was measured. magnetic field was generated by a solenoid coil and magnetic signature was measured by a magnetic field sensor. A linearity between a vertical bias magnetic field and a vertical manetzation existed and the vertical magnetization of a miltary vessel was predicted by the linearity.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.655-656
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• 2006

대부분의 초전도 전력기기의 경우, 초전도 테이프를 솔레노이드나, 팬케�� 형태로 권선해서 사용하게 되고, 이러한 경우에는 권선을 구성하는 테이프들에 흐르는 전류에 의해 발생하는 자계는 권선내의 각각의 테이프에 임의 방향의 외부 인가자계로 작용하여 자화손실을 발생시키므로 초전도 코일에서의 교류손실을 평가하고 예측하기 위해서는 임의방향 자장에 의한 자화손실에 대한 데이터가 필요하다. 수직 자화손실에 대한 측정값으로서 임의방향 자장에 의한 자화손실을 알 수 있다면 코일의 교류손실 평가는 훨씬 쉽게 접근할 수 있을 것이다. 본 논문에서는 측정된 자화손실 값들로부터 각 방향 인가자장에 의한 자화손실과 인가된 자장을 분리하여 수직방향 및 수평방향 성분에 의한 자화손실 측정값의 합과 비교하여 각도별로 두 자화손실의 차이를 살펴보았다.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.851-853
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• 2002

Bi-2223도체의 종자계 손실에 대하여 실험적으로 조사하였으며, Bi-2223도체의 종자계 손실은 주파수에는 의존하지 않으며, 이는 수직 수평방향의 자장에 대한 자화손실처럼 히스테리시스손실이 지배적임을 의미한다. 또한 측정된 자계 손실은 절충 본수에도 그다지 의존하지 않으며, 필라멘트들 사이가 완전히 비결합된 모델로부터 계산된 손실에 더 유사하고, 수평방향의 자장에 대한 자화손실의 약 1/5정도로 작으며, 따라서 종자계 손실은 전력기기에서 그다지 중요하지 않음을 알수 있었다.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.434-437
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• 2011

본 논문에서는 H.264/AVC 복호기의 성능을 향상시키기 위해 병렬 역양자화 구조와 역변환 구조를 제안한다. 제안하는 역양자화 구조는 공통 연산기를 사용하여 계산 복잡도를 감소시키고, 4개의 공통연산기를 사용하여 역양자화 수행 사이클 수를 1 사이클로 감소시킨다. 제안하는 역변환 구조는 4개의 변환 연산기를 사용하여 역변환 연산을 수행하는데 2 사이클이 소요된다. 또한 제안하는 구조는 역양자화 연산과 수평 역변환 연산을 동시에 수행하는 병렬 구조를 채택하여 역양자화 및 역변환 수행 사이클 수를 2 사이클로 감소시킨다. 제안하는 구조를 Magnachip 0.18um CMOS 공정 라이브러리를 이용하여 합성한 결과 1.5MHz의 동작 주파수에서 게이트 수는 14,173이고, 표준 참조 소프트웨어 JM 9.4에서 추출한 데이터를 이용하여 성능을 측정한 결과 제안하는 구조의 수행 사이클 수가 기존 구조 대비 38.74% 향상되었다.

• Journal of radiological science and technology
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• v.40 no.1
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• pp.19-25
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• 2017

The aim of this study was to evaluate Magnetic Resonance Imaging safety by measuring the translational attraction, torque and susceptibility artifact for Bone-Anchored Hearing Aid (BAHA) implant at 1.5 T and 3.0 T MRI by standard criteria. In vitro assessment tools were made of acrylic-resin by American Society for Testing and Materials (ASTM) F2052-06 and F2119-07 standard. Translational attraction of BAHA implant was measured by the maximum deflection angle at 96 cm position, where the magnetically induced deflection was the greatest. The torque was assessed by the qualitative criteria of evaluating the alignment and rotation pattern, when the BAHA implant was positioned on a line with $45^{\circ}$ intervals inside the circular container in the center of the bore. The susceptibility artifact images were obtained using the hanged test tool, which was filled with $CuSO_4$ solution. And then the artifact size was measured using Susceptibility A rtifact Measurement (SA M) software. In results, the translational attraction was 0 mm at both 1.5 T and 3.0 T and the torque was 0(no torque) at 1.5 T, and +1(mild torque) at 3.0 T. The size of susceptibility artifacts was between 13.20 mm and 38.91 mm. Therefore, The BAHA implant was safe for the patient in clinical MR environment.

• Journal of the Korean Magnetics Society
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• v.6 no.4
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• pp.199-203
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• 1996

To study the magnetization reversal behavior of Co/Pd multilayers, we first demagnetized the samples by the field-demagnetized method and then measured initial curves and minor loops. The coercivity and the perpendicular magnetic anisotropy were obtained from the perpendicular and parallel magnetization curves measured at different temperatures. We interpret our experimental results by applying several qualitative and semiquantative approaches. From these study, we found that the magnetization reversal behavior is dominated by the domain wall pinning for all samples and the coercivity incremental tendency can be explained by Kronmuller's formula $H_c(T)\;{\propto}\;r_0.K_u$.

• Journal of the Korean Magnetics Society
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• v.23 no.2
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• pp.37-42
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• 2013

The out-of-plane and in-plane angular dependence of ferromagnetic resonance field was measured in NiFe thin films fabricated by magnetron sputtering. The effective magnetization was obtained from the out-of-plane angular dependence of ferromagnetic resonance field, which was well agreed with calculated one. The decrease of effective magnetization with NiFe thickness was due to the surface anisotropy constant of $K_s=-0.23\;erg/cm^2$. The in-plane uniaxial anisotropy fields were obtained from the in-plane angular dependence of ferromagnetic resonance field. The easy axis of in-plane uniaxial anisotropy field was rotated to the reverse direction of applied magnetic field during sample fabrication, which was explained by the antiferromagnetic NiFeO layer at sample surface.

• Journal of the Korean Magnetics Society
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• v.23 no.1
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• pp.12-17
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• 2013

Nanocrystalline nickel (Ni) tick films were synthesized by direct current electrodeposition at current density from 1 to $30mA/cm^2$ and pH = 4. The basic composition of the bath, which was prepared by dissolving Ni metal particles in HCl, was 0.2M Ni ions. The effects of the current density on the average grain size of Ni deposits were investigated by XRD and SEM techniques. The results showed that the surface roughness was decreased as the saccharin addition was increased up to 2 g/l. The experimental results showed that the increase in the current density had a considerable effect on the average grain size of the Ni deposits. The perpendicular magnetization was raised as the thickness of coating layer was increased.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.445-450
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• 2016

This paper studied on the influence of naval vessel shape on vertical magnetic field after the vessel was demagnetized. The triangular shape, the rectangular shape and circular shape were adaped from vessel's structual drawings. Magneto-static FEM analysis was performed to obtain the iduced magnetic field due to earth magnetic field for those shapes. During demagnetization process, magnetic field of residual magnetization was observed. The holizontal and vertical magnetic field were calculated depending on vertical bias magnetic field through magnetc component seperation. To demagnetize naval vessel ship, demagnetizing coils shoud be wound more finely in the vow and stern of the ship than it should be in the mid-part of the ship.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.9-11
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• 2001

현 단계에서도 임계전류밀도가 약 $100A/mm^2$로 충분히 높아 전력분야 응용이 기대되는 Bi-2223테이프에 대한 교류손실을 초전도 전력기기의 실제 상황을 고려하여 측정하였다. 중요한 평가 결과로서는 먼저 통전손실 특성은 외부 교류자장의 세기뿐만 아니라 방향에 따라서도 매우 상이하였으며, 비교적 외부자장이 큰 경우는 동저항손실 메카니즘이, 작은 경우는 그 외의 또 다른 손실 메카니즘이 지배적이었다. 또한 수평자장에 대한 자화손실 특성은 코아 모델로부터 계산된 손실과 비교적 잘 일치하였다. 따라서 자화손실은 히스테리시스 손실 메카니즘이 지배적이라 할 수 있으며, 측정된 자화손실은 저온 초전도체에서는 볼 수 없었던 약한 주파수 의존성을 보였을 뿐만 아니라 외부자장의 세기에 따라서도 주파수 의존 특성이 상이하였다.